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An Interesting Lecture on the Technological Coding of Racism Is Now Online.

I saw it live a few weeks ago, and found it rather inspiring and informative. I originally posted about it in the science section.

It's worth watching:

It is here: Science on Saturday: Dr. Ruha Benjamin: Will Robots Save Us or Slay Us?

Electrolytic reduction of carbon dioxide to yield multicarbon products

The paper I'll discuss in this post is this one: CO2 electrolysis to multicarbon products at activities greater than 1 A cm^(−2) (F. Pelayo García de Arque al, Science, Vol. 367, Issue 6478, pp. 661-666).

There is a growing, and frankly delusional, belief that electricity is "green," i.e. that is inherently sustainable and clean. This is pure nonsense. First of all, except possibly in the case of lightening which is not utilized to charge Tesla cars, electricity is not primary energy. Since it must be made from a source of primary energy, it is therefore, by appeal to the inviolable laws of thermodynamics, a degraded form of energy: Whenever electricity is generated, irrespective of how it is generated, some energy is lost to entropy. Moreover, electricity must be either used when it is generated, or stored, with additional thermodynamic loses, as chemical energy, usually in the form of batteries, batteries representing a rising threat to the environment whether we get it or not.

This pernicious fantasy which helping to push the planetary ecosystem over an abyss that we cannot even remotely imagine, is based on an unsubstantiated bit of nonsense that pretends, in Trumpian contempt for reality, that electricity is, or soon will be, generated by another pernicious, but popular, fantasy, so called "renewable energy." In turn, so called "renewable energy" is not clean and is not sustainable. Even it it were, despite all the cheering, it is largely ineffective at producing energy, and the two trillion dollars per decade squandered on it - the current rate - will not change that fact. In this century the growth in the use of so called "renewable energy" has been dwarfed by the increases in the use of dangerous coal, the use of dangerous petroleum, and the use of dangerous natural gas. This is true in every area of energy use, but it is equally so in the case of electricity generation.

The International Energy Agency puts out, every year, along with the World Energy Outlook, to which I often refer, a document called "Electricity Information." Here is a link to the 2019 Edition: Electricity Information 2019: Overview

Here is a graphic from it:

Coal remained, as of 2017, the world's largest source of primary energy used to generate electricity.

A similar graphic, in the same document, on the same page, shows the actual primary energy generated by all fuels:

Both graphics show how successful, for all the cheering, and the trillions of dollars thrown at it, so called "renewable energy" has been in displacing dangerous fossil fuels, which is to say not all. None of this experimental data, however, will prevent advocates of this scheme to turn our remaining (and vanishing) wilderness areas into industrial parks for wind turbine and solar farms, for no meaningful result. The use of dangerous fossil fuels, not just to produce electricity, but for all purposes, is rising, not falling.

On page II.4 of the EIA Electricity Information Document, is a rather large table (Table 1.0 of section II of the report) relating to energy use in general and what proportions of it involves the generation electricity.

The table contains some interesting information about the use of coal for purposes other than generating electricity or heat, with three categories, steel production, non-ferous metals, and non-metal mineral processing (probably mostly representing concrete production) - the demand for all three will rise in the worst case scenario, where the world continues to expand so called "renewable energy" - amounted to about 23.3 exajoules of energy. Other ancillary uses for coal also require prodigious amounts of this rather unsustainable material.

I won't reproduce the table here, but note that, with some calculation - which I have done - one can obtain the thermodynamic efficiency of all the major forms of energy utilized to generate electricity, as well what fraction of the total generation derives from a particular source of primary energy. The following table is the result of my calculations from Table 1.0 of section II.

To the extent that CHP, combined heat and power, is present, suggests that, at least in Winter months, not all of the entropy (heat) losses are truly wasted, but the fact is that overall, for all types of plants that produce electricity - clearly these tables ignore transmission losses, since otherwise hydroelectricity would not be recorded as 100% efficient - the energy efficiency is 42.31%.

(In fact, no system for generating electricity can actually work at 100% efficiency, as is stated in this table for hydroelectricity. The "100%" figure ignores that the system is inefficient when the primary energy to drive the hydroelectric turbines is actually gravitational energy associated with the mass of water that falls through the turbine. It is probably too painful to calculate, and so we have this somewhat disingenuous 100% figure. With this in mind, we should not that the 42.31% figure is clearly too high, since hydroelectricity produces about 15% of the world's electricity. In any case, we are almost fresh out of major rivers to destroy with hydroelectric plants. The less than 100% efficiency for so called "renewable energy" is difficult to explain in the same terms - except for geothermal - and may reflect the fact that it is often required to dump so called "renewable energy" because of saturated grids, where there is too much wind and solar with the result that every energy system on that grid, including so called "renewable energy," is economically useless to the owners of the plants. It also may reflect the use of batteries. Who cares? So called "renewable energy" is best at generating not energy, but rather at generating evidence of its uselessness.)

The point is, overall, that electricity is a degraded form of primary energy. The highest efficiency for a thermal system, belongs to dangerous natural gas fuels, a point to which I will return briefly in the summary of this post, since although dangerous natural gas is in no way a sustainable or acceptable fuel - it must be phased out in its entirety - one can certainly learn from how it is used to achieve higher thermodynamic efficiency than other systems.

Therefore, when one stores electricity in a chemical form - a practice in itself that is never 100% efficient, one further degrades the energy efficiency of the system. That is true for batteries, and it is true for the electrochemical reduction of carbon dioxide described in the paper referenced at the outset of this post.

The paper begins with the typical rote obeisance - found in almost all energy storage papers these days - to so called "renewable energy."

The electrochemical transformation of gases into value-added products using renewable energy is an attractive route to upgrade CO2 and CO into fuels and chemical feedstocks (1–4) based on hydrocarbons. The success of the approach will rely on continued improvements in energy efficiency to minimize operating costs and on increasing current density to minimize capital costs (5, 6). This will require catalysts that facilitate adsorption, coupling, and hydrogenation via proton-coupled electron transfer steps (7–9).

In these reactions, water-based electrolytes act both as a proton source and as the ion conductive medium (10). However, the solubility of these gases in water is limited, leading to constrained gas diffusion as gas molecules collide or react with their environment (11). The diffusion length of CO2 can be as low as tens of nanometers in alkaline aqueous environments (12). This has limited the productivity of catalysts in aqueous cells to current densities in the range of tens of milliamperes per square centimeter due to mass transport (13–16).

In a gas-phase electrolyzer, catalyst layers are deposited onto hydrophobic gas-diffusion layers so that gas reactants need to diffuse only short distances to reach electroactive sites on the catalyst surface (Fig. 1A) (17–19). Gas reactant diffusion in the catalyst layer becomes the mass transport–limiting step in the cathode, as observed in the oxygen reduction reaction (ORR) in fuel cells. To improve ORR performance, fuel-cell catalyst layers are designed to balance hydrophobicity to help expel water and hydrophilicity to maintain sufficient ion conductivity.

In contrast with oxygen reduction, which generates water as a product, CO2 reduction requires water as a proton source for hydrocarbon production. Thus, the catalyst layer is hydrophilic and fully hydrated during the reaction. In this configuration, CO2 electrochemical reactions occur within a gas-liquid-solid three-phase reaction interface (Fig. 1B) (20). This volume, in which gaseous reactants and electrolytes coexist at catalyst electroactive sites, decays rapidly into the electrolyte, particularly at the high pH used in alkaline electrolysis. The decay is further increased at high current densities because of local OH− generation (21). A large fraction of the catalyst is in contact with electrolyte in which CO2 availability is limited by its solubility (<2 mM at pH 15). Because hydrogen evolution is a competing reaction with CO2 reduction in a similar applied potential range, the large fraction of catalyst surface area exposed to CO2-depleted electrolyte promotes undesired H2 generation (Fig. 1C). Whereas recent advances in gas-phase CO2 reduction have led to partial current densities for CO2 reduction of ≈100 mA cm−2 (12, 22, 23), other liquid-phase electrochemical technologies such as water electrolysis achieve multi-amperes per square centimeter (24, 25).

Figure 1:

The caption:

Fig. 1 Limiting current in gas-phase electrocatalysis and ionomer gas-liquid decoupled transport channels.
(A) Flow-cell schematic. Reactant gases are fed through the back of a gas diffusion–electrode catalyst, facing an aqueous electrolyte. An anion-exchange membrane (AEM) facilitates OH− transport from cathode to anode. GDL, gas-diffusion layer. (B) In a gas-diffusion electrode (GDE), catalysts are deposited onto a hydrophobic support from which gas reactants [G] diffuse. (C) The volume in which gas reactants, active sites, and water and ions coexist determines the maximum available current for gas electrolysis. Catalyst regions with limited reactant concentration promote by-product reactions such as hydrogen evolution. (D) When gas and electrolyte (water and ion source) transport is decoupled, the three-phase reaction interface can be extended so that all electrons participate in the desired electrochemical reaction. (E and F) Modeled gas reactant availability along the catalyst’s surface for standard (E) and decoupled (F) gas transport into a 5 M KOH electrolyte, assuming an in-plane laminar gas diffusivity of D‖/DKOH = 1000 for the latter, where D‖ is gas diffusivity parallel to catalyst surface. Depending on the gas diffusivity within the gas transport channel, gas availability dramatically increases. L‖, distance parallel to catalyst surface; L⊥, distance perpendicular to catalyst surface. (G) Modeled maximum available current density for CO2 reduction. D/DKOH manipulation enables entrance into the >1–A cm−2 regime for CO2R. See methods for details on gas transport and reaction simulations.

This is a gas phase system, which involves gas phase water (steam), and thus involves high temperatures which can only be provided by wind and solar so called "renewable energy" via an electricity intermediate, again, thermodynamically degraded energy:

High-temperature solid oxide electrolysis offers a strategy to achieve CO2 reduction at high current density: CO2 diffuses directly to the surface of the catalyst, in the absence of liquid electrolyte, thus overcoming the gas diffusion limitations of low-temperature systems. However, high-temperature conditions and the absence of liquid electrolyte have thus far limited CO2 reduction to the production to CO (26).

Here, we present a hybrid catalyst design that, by decoupling gas, ion, and electron transport, enables efficient CO2 and CO gas-phase electrolysis at current densities in the >1–A cm−2 regime to generate multicarbon products. We exploit an ionomer layer that, with hydrophobic and hydrophilic functionalities, assembles into a morphology with differentiated domains that favor gas and ion transport routes, conformally, over the metal surface: Gas transport is promoted through a side chain of hydrophobic domains, leading to extended gas diffusion, whereas water uptake and ion transport occur through hydrated hydrophilic domains (Fig. 1D). As a result, the reaction interface at which these three components come together—gaseous reactants, ions, and electrons—all at catalytically active sites, is increased from the submicrometer regime to the several micrometer length scale.

The system that the authors design is a functionalized type Nafion based system of electrodes. Nafion is a fluoropolymer. In general, fluoropolymers, while extremely useful, are a source of the intractable fluoroalkane (PFOS, PFOA) contamination issue that has become recently an area of increasing environmental concern.

Figure 2 of the paper:

The caption:

Fig. 2 The catalyst:ionomer planar heterojunction.
(A) Schematic of metal catalyst deposited onto a PTFE hydrophobic fiber support. A flat ionomer layer conformally coats the metal. (B) Perfluorinated ionomers such as Nafion exhibit differentiated hydrophilic and hydrophobic characteristics endowed by –SO3– and –CF2 functionalities, respectively. Laminar Nafion arrangements have been reported depending on its thickness and substrate (37, 40). (C and D) SEM images of ionomer-coated copper catalysts. (E to G) Cryo-microtomed TEM cross-sections of catalyst and ionomer revealing a laminar conformal overcoating. (H) WAXS spectra for reference and ionomer-modified catalysts. These reveal features at 1, 1.28, and 2 A−1, associated with various PFSA and PTFE-support phases. (I) Raman spectra of reference and ionomer-modified catalysts revealing distinctive features of ionomer –CF2 and –SO3− groups (table S5).

Figure 3 shows limiting currents for these systems:

In the caption, "RR" stands for "reduction reaction" and "ORR" stands for "oxygen reduction reaction," CORR for "carbon monoxide reduction reaction" and CO2RR to "carbon dioxide reduction reaction." CIPH refers to "catalyst:ionomer planar heterojunction" which refers to the type of electrodes the authors have developed in this paper.

The caption:

Fig. 3 Increased limiting current and underlying mechanisms for CIPH catalysts.
(A) ORR showing a 30–mA cm−2 limiting current (Jlim) for Ag reference catalysts as opposed to 250 mA cm−2 for a CIPH configuration. RHE, reversible hydrogen electrode. (B) For CO2RR, standard Ag catalysts yield a Jlim of ≈54 mA cm−2 (remaining current used for hydrogen evolution). This is in stark contrast with CIPH samples, which retain a FE above 85% for CO2 reduction (CO2R) to CO up to ≈500 mA cm−2. (C) This trend is maintained for Cu CIPH catalysts and hydrocarbon production: Jlim toward ethylene (dominant product) is 50 mA cm−2 at −0.7 V versus RHE for bare Cu but increases beyond 0.5 A cm−2 for CIPH (peak FE of 61% at 835 mA cm−2). (D) For CO reduction (COR), Jlim ≈ 64 mA cm−2 for standard Cu, whereas CIPH achieves a maximum 340–mA cm−2 current for the same reaction; H2 by-product generation is restrained below 15% FE at all currents. (E and F) Partial pressure COR studies in CO|N2 mixes for CIPH (E) and standard (F) catalyst show that only at partial pressures below 60% is Jlim observed for CIPH, whereas a sharp, steady decrease is observed for reference samples. At all partial pressures, CIPH exhibits an order of magnitude larger Jlim. Both reference and CIPH samples exhibit comparable resistance and double-layer capacitance. Electrochemical experiments were carried out in 5 M KOH electrolyte with a 50–cm3 min−1 CO or CO2 feedstock (in the case of 100% partial pressure).

The unusual, and important point about this technology is the fact that it produces ethylene, which is the monomer utilized to make the polymer polyethylene, and is also a useful intermediate for the production of many other types of polymers and chemicals, including, but certainly not limited to, ethanol. As such, the technology allows for the elimination of the use of dangerous fossil fuels in the manufacture of this intermediate, thus eliminating their contribution to climate change - which is not to say we give a rat's ass about climate change; clearly we don't. If we did, we'd stop carrying on about so called "renewable energy" - since it has been experimentally determined to be useless at addressing climate change.

Some interesting stuff about the catalyst morphology is shown in figure 4:

The caption:

Fig. 4 3D catalyst:ionomer bulk heterojunction for efficient gas-phase electrochemistry beyond 1 A cm−2.
(A) Schematic representation of metal-ionomer bulk heterojunction catalysts on a PTFE support. (B) Cross-sectional SEM of the CIBH catalyst. (C and D) TEM image of a cryo-microtomed CIBH (C) and elemental mapping of Cu and C revealing CIBH nanomorphology (D). (E) Partial current density for total CO2RR reactions, with C2+ and C2H4 at maximum cathodic energy efficiency. The total CO2R current saturates at 1.3 A cm−2 before cathodic energy efficiency drops for CIBH thicknesses beyond 6 μm. CIBH samples achieve more than a sixfold increase in partial current density at cathodic energy efficiencies >40% (fig. S30). Each sample and operating condition ran for at least 30 min. (F) Performance statistics of the highest partial current configuration for eight Cu CIBH catalysts. The box plot corresponds to Q1 to Q3 interquartile range, median, and average. The error bar represents ≈5.4 standard deviations. EE1/2, half-cell (cathodic) energy efficiency. (G) Performance of the best CIBH catalyst in an ultraslim flow cell consisting of a 3-mm-wide catholyte channel. A full-cell energy efficiency of 20% for C2+ products is estimated at 1.1–A cm−2 operating current. All CIBH electrochemical experiments were carried out in 7 M KOH with a 50–cm3 min−1 CO2 feedstock.

The authors conclude their article with a discussion of efficiency and of course, evocation of the wonder word "renewable:"

As we increased catalyst loading and corresponding thickness, we observed a monotonic increase in the total CO2RR current, which surpassed 1 A cm−2 for a loading of 3.33 mg cm−2 (5.7 μm thickness) and which saturated at 1.32 A cm−2 for higher loadings before energy efficiency dropped (Fig. 4E). The total partial current for C2+ products (ethylene, ethanol, acetate, and propanol) reached 1.21 A cm−2 (fig. S29), which was achieved at a 45 ± 2% cathodic energy efficiency. The achieved C2+ partial current density represents a sixfold increase compared with previous best reports at similar energy efficiencies (12, 22, 23) (fig. S30 and tables S6 to S9).

The product distribution for optimal CIBH catalysts at different current densities in 7 M KOH electrolyte reveals that H2 generation remains below 10% from 0.2 to 1.5 A cm−2 (fig. S29). At the highest current operation, optimized catalysts exhibited a maximum productivity toward ethylene with a FE in the 65 to 75% range, a peak partial current density of 1.34 A cm−2 at a cathodic energy efficiency of 46 ± 3% (Fig. 4F and figs. S31 and S32). We implemented the best CIBH catalyst in an ultraslim flow cell (with no reference electrode and a minimized catholyte channel of ≈3 mm, with water oxidized at a Ni foam anode), leading to an estimated full-cell energy efficiency toward C2+ products of 20% at 1.1 A cm−2 without the benefit of iR compensation (i, current; R, resistance) (Fig. 4G). CIBH catalyst current and FE remained stable over the course of a 60-hour initial study implemented in a membrane electrode assembly configuration (fig. S33).

Although CO2 reduction kinetics improve with increasing temperature, alkaline electrolyzers manifest worsened CO2 availability as temperature increases, and this fact curtails reaction productivity. We explored the effect of temperature on planar CIPH metal:ionomer catalysts and observed that CIPH catalysts require lower overpotentials to attain similar FE, in contrast with planar reference catalysts (fig. S34), when operated at 60°C. This effect translates into 3D CIBH catalysts, which show improved performance arising from the combination of accelerated CO2 reduction kinetics and extended mass transport through the ionomer layer with increasing temperature (fig. S35). As a result, CIBH catalysts achieve ≈1 V reduced overpotential and more than a 50% increase in C2 productivity when operated at industrial electrolyzer-relevant temperatures of 60°C in a full-cell configuration, compared with the case of room temperature operation (fig. S36).

The phenomena described herein showcase catalyst design principles that are not constrained by prior gas-ion-electron transport restrictions. The CIBH catalyst paves the way to the realization of renewable electrochemistry for hydrocarbon production at operating currents needed for industrial applications, as has been achieved with syngas for solid oxide electrolyzers (48, 49).

The cathodic efficiency comes from the efficiency of converting electricity - thermodynamically degraded energy - into these products. It does not include the thermodynamic cost of separating the four products, although the separation of ethylene gas is something of a no-brainer.

I don't believe for a New York second that this technology is applicable in an economically or environmentally acceptable fashion to so called "renewable energy." The economics of any production system depends very much on its capacity utilization. Since the capacity utilization of the mass intensive so called "renewable energy" industry is low, and decoupled intrinsically from demand loads, it follows that the capacity utilization of these systems in so called "renewable energy" systems will be even lower. Thus for long periods, the capacity built to construct such a system will be generating zero value to an investor, and moreover, the return on investment will be unpredictable.

Nevertheless may be useful in limited applications, depending on the design of a power grid, for continuous operation systems. The power grid in most places is uneven. Generally peak loads on grids occurs in the early evenings and late afternoons. If the output of so called "renewable energy" systems in places where they have foolishly represent a large portion of the grid sources is momentarily high, all power sources return nothing to their investors, and for systems that are reliable but uneconomical at random points, to be available for those times when the sun is not shining and the wind not blowing, to survive they must recover their costs in the periods in which they are required to operate to prevent blackouts. This is why Denmark and Germany have the highest retail electricity prices in the OECD.

Nuclear power plants operate best at close to 100% capacity utilization. As the table above shows, they operate at unacceptably low thermodynamic efficiency, about 33%. The reason for this is that the basic technology under which they were built was to produce electricity; they were designed to be coal plants without the coal. They operate overwhelmingly (with some exceptions) on Rankine (steam) cycles.

We know from the much discussed events at Three Mile Island and Fukushima - events that garner far more attention than 70 million deaths from air pollution every decade - (and of course from engineering and science courses, were we interested in taking them) that nuclear fuels can produce heat that is much higher than the boiling point of water. It is possible to use these high temperatures to skip the thermodynamically degraded electricity intermediate to increase thermodynamic efficiency by simply proceeding directly to chemical storage using heat. Thermochemical cycles to do this are well known and widely studied. In fact, they can be operated synergistically with electricity production, for example using a modified Allam cycle, a heat engine cycle I discussed elsewhere in this space.

It is the use of two heat engine cycles in tandem that accounts for the high thermodynamic efficiency of gas plants: They have Brayton cycles (of which Allam cycles are a subset) coupled to Rankine cycles, using the waste heat from the high temperature cycle, the Brayton cycle, to drive the lower temperature cycle, the Rankine cycle. Their are other possibilities to go beyond these, thermochemical cycles (which represent stored energy as fuels or materials) coupled to Brayton cycles (with a carbon dioxide working fluid) driving a Rankine steam cycle, with high efficiency thermoelectric devices and or Stirling engines being possibly added in the temperature reduction line. This would have the added advantage of reducing the water demand for cooling of such plants, although it is also possible to put a desalination scheme somewhere in the line. There is a world of better ways to do things.

All of these high temperature high efficiency schemes are dependent on access to continuous reliable energy that is also clean and sustainable. This limits the choice to one source of primary energy, nuclear energy.

As for the electrochemical reduction of carbon dioxide, it might be utilized, in the limited setting of preventing the waste associated with spinning reserve, depending on the economic cost of the entire system and its relationship to capacity utilization. Spinning reserve is the amount of power that is generated to cover fast and short term and unexpected surges in demand on the system without producing brown outs. To the extent that this energy, when not in demand, is utilized to drive the electrochemical reduction of carbon dioxide to ethylene, it's certainly worth consideration.

I wish you a pleasant and productive workweek.

Climate change contributes to widespread declines among bumble bees across continents.

The paper I'll discuss in this post, having the same title as the post, is this one: Climate change contributes to widespread declines among bumble bees across continents (Peter Soroye1,*, Tim Newbold2, Jeremy Kerr1, Science Vol. 367, Issue 6478, pp. 685-688 2020)

Reference to the article is included in a news item in the same issue of science, from which I'll quote before referring to the paper itself, since it is so well written, and makes a trenchant ecological political point. The news item:

Discovering the limits of ecological resilience (Jon Bridle, Alexandra van Rensburg, Science Vol. 367, Issue 6478, pp. 626-627, 2020).

To wit:

n 1949, environmentalist Aldo Leopold wrote that “one of the penalties of an ecological education is that one lives alone in a world of wounds” (1). Seventy years later, biologists no longer witness such wounds in solitude. Instead, millions of people on social media share evidence every day of how the behavior of a wealthy minority (2) has created unsustainable rates of biodiversity loss and climate transformation (3). Now, on page 685 of this issue, Soroye et al. demonstrate widespread declines in bumble bee species that are better explained by the frequency of climate extremes than by changes in average temperatures (4).

The, um, behavior of a wealthy minority...

Of course, here we like to argue that the wealthy minority consists of people, venal people who are not us, you know, Donald Trump, Koch, Koch, Koch, Koch, Adelson, Murdoch, Murdoch...

We're not "rich."

Bridle and van Rensberg continue:

Despite increasingly precise predictions of rises in average temperatures and the frequency of extreme weather events, biologists still cannot predict how ecological communities will respond to these changes. This means that scientists cannot predict where, and at what rates of climate change, ecosystems will stop providing the rainfall, decomposition, and biological productivity on which all economies depend. Another key unknown is to what extent ongoing habitat and biodiversity loss reduces the ability of ecological communities to evolve in response to the climate crisis (3).

To determine these critical rates of biodiversity loss and climate change as well as where they are being exceeded (5), scientists test for shifts in the distribution of species over time and across their geographical ranges. Such studies reveal that the warming climate leaves a footprint: The abundances of many plant, animal, and fungal species have contracted at low latitudes and elevations, and have increased at high latitudes and elevations (6). How these responses to environmental change vary according to species' life histories, ecologies, and their biotic interactions provides a test of which ecosystems and localities are least resilient to global change.

Soroye et al. used long-term datasets to assess changes in the abundance and geographical distribution of 66 bumble bee species in Europe and North America between two periods, 1901–1974 and 2000–2014. Two of their findings are especially alarming. Bumble bee populations showed substantial declines at southern (warming) ecological margins but fewer compensating population expansions at northern (cooler) margins, suggesting widespread declines in bee biodiversity across both continents. Moreover, the causes of these declines apparently depend more on the frequency of extremely warm years than on increases in average temperatures. As prevailing temperatures climb closer to species' physiological limits, extreme climate events will become increasingly associated with biodiversity loss. In addition, their effects will become more pronounced as cooler habitats, where organisms can survive unusually warm periods (e.g., deeper water, higher elevations), become increasingly rare...

The behavior of a wealthy minority...

We're not rich. Really, we're not.

I personally rail quite a bit about a little fact that um, troubles me:

Today, 2.2 billion people lack access to safely managed drinking water services and 4.2 billion people lack safely managed sanitation services. Unsafe hygiene practices are widespread, compounding the effects on people’s health. The impact on child mortality rates is devastating with more than 297 000 children under five who die annually from diarrhoeal diseases due to poor sanitation, poor hygiene, or unsafe drinking water.

United Nations Water: Water, Sanitation and Hygiene

If any of this troubles you, don't worry, be happy.

Head over to the E&E forum where you can read about the wonders of Elon Musk's car for spoiled children, which is built using cobalt mined by real children working for zero wages under the point of guns, um, slaves, in "The 'Democratic' 'Republic' of the Congo"

"Energy Sage"

The annual per capita income of "The 'Democratic' 'Republic' of the Congo" is reportedly $562, less than $2.00/day.

The "cheap" Tesla car costs more than 60 times the per capita income of "The 'Democratic' 'Republic' of the Congo." The, um, luxury model, costs "only" 220 times as much.

Don't worry, be happy. If you own a Tesla car, you're not rich; you're "green."

Those kids digging cobalt are not afforded the luxury of being green with envy as they admire your Tesla car. They've probably never seen one. They are probably not even aware of what this is all about; since even that would require a rudimentary education. The guns and the whips are all they need to know to understand what this is all about.

Don't worry. Be happy. All that fracking is transitional because soon enough we will drag giant steel posts for wind turbines through every virgin ecosystem on the planet and be "green." We swear. We swear. We'll build those wind farms right on through 500 ppm of CO2, and be so proud of ourselves for being "green."

You're not rich, because you live in a country that is the world's largest debtor, run by a brainless cheap carny hack criminal who is the pet puppy of an ex-KGB agent and who is coddled by a bunch of thugs who used to wrap themselves in American flags and complain about "those commies."

You're not rich. You had nothing to do with those bumble bees and their bumble bee problems.

About the bees, from the introduction to the paper cited at the outset:

Recent climate changes have accelerated range losses among many species (1, 2). Variation in species’ extinction risk or chances of colonizing a new area determine whether species’ ranges expand or decline as new climatic conditions emerge. Understanding how changing climatic conditions alter species’ local extinction (extirpation) or colonization probabilities has proven exceptionally challenging, particularly in the presence of other environmental changes, such as habitat loss. Furthermore, identifying which species will most likely be at risk from climate change and where those risks will be greatest is critical to the development of conservation strategies (3, 4).

Although many mechanisms could alter how species fare as climate changes, discovering processes that strongly affect species persistence remains among the foremost challenges in conservation (5). Climate change could pose risks to species in part by increasing the frequency of environmental conditions that exceed species’ tolerances, causing population decline and potentially extirpation (6, 7). Conversely, climate change may render marginal areas more suitable for a species, making colonization of that locale more likely (1). Understanding and predicting spatially explicit colonization and extinction likelihood could identify which species are vulnerable to climate change and where, identify which species may benefit, and suggest interventions to mitigate conservation risks. Colonization and extinction dynamics, in combination across a regional species assemblage, determine how species richness changes. Among taxa that contribute critically to ecosystem service provision, including pollinators such as bumble bees (Bombus), species richness decline could impair ecosystem services (8).

We evaluated changes in bumble bee species occupancy and regional richness across North America and Europe using a database of ~550,000 georeferenced occurrence records of 66 bumble bee species (figs. S1 and S2 and table S1) (1, 9). We estimated species’ distributions in quadrats that measured 100 km by 100 km, in a baseline (1901–1974) and recent period (2000–2014) (9). Climate across Europe and North America has changed greatly between these time periods (fig. S3). Although the baseline period was substantially longer, there were 49% more records in the recent period. Non–detection bias (difficulty distinguishing among true and false absences due to imperfect detection) in opportunistic occurrence records can reduce measurement accuracy of species distributions and overall richness (10). Consequently, we used detection-corrected occupancy models to estimate probability of occurrence for each species in quadrats in each time period (9). We calculated changes in species’ probabilities of occupancy and generated detection-corrected estimates of species richness change between periods (fig. S4).

We predict greater declines in bumble bee species occupancy and species richness where changing climatic conditions more frequently exceed individual species’ historically observed tolerances. Conversely, we predict greater occupancy and species richness in areas where climate changes more frequently cause local weather to fall within species’ historically observed tolerances.

Figure 1 from the paper:

The caption:

Fig. 1 Change in community-averaged measures from the baseline (1901–1974) to the recent period (2000–2015).

Local changes in (A) thermal and (B) precipitation position indices are shown. Increases indicate warmer or wetter regions and that, on average, species in a given assemblage are closer to their hot or wet limits than they have been historically. Declines indicate cooling or drying regions and that, on average, species in a given assemblage are closer to their cold or wet limits than they have been historically

More text:

...Our measurements of bumble bee species occupancy over time provide evidence of rapid and widespread declines across Europe and North America. The probability of site occupancy declined on average by 46% (±3.3% SE) in North America and 17% (±4.9% SE) in Europe relative to the baseline period (Fig. 2). Declines were robust to detection-correction methods (figs. S6A and S7) and consistent with reductions in detection-corrected species richness (fig. S6B) (9)...

Figure 2:

The caption:

Fig. 2 Percent change in site occupancy since a baseline period (1901–1974) for 35 North American and 36 European bumble bee species.

More text:

...Declines among bumble bee species relate to the frequency and extent to which climatic conditions approach or exceed species’ historically observed climatic limits, particularly for temperature. We modeled change in probability of site occupancy with phylogenetic generalized linear mixed models using thermal position variables (baseline, change since baseline, and the interaction between these), precipitation position variables (baseline, change since baseline, and the interaction between these), the interaction between baseline thermal and precipitation position terms, and the interaction between change in thermal position and change in precipitation position. We controlled for continent (9). The models support our predictions: Probability of occupancy decreases when temperatures rise above species’ upper thermal limits (Fig. 3A, fig. S8A, and table S2), whereas warming in regions that were previously near species’ cold limits is associated with increasing occupancy. Evidence for precipitation influencing site occupancy was mixed, but declines were more likely in sites that became drier (Fig. 3B, fig. S8B, and table S2)...

Figure 3:

The caption:

Fig. 3 Change in probability of occupancy in response to change in thermal and precipitation position from the baseline (1901–1974) to the recent period (2000–2014).

Thermal (A) and precipitation (B) positions range from 0 to 1, with 1 indicating that conditions at a site are at a species’s hot or wet limit for the entire year and 0 meaning that conditions are at a species’s cold or dry limit for the entire year during the historic period. For ease of visualizing the significant interaction between baseline thermal position and change in thermal position, the continuous baseline thermal position variable has been split at the first and third quantile to show sites that were historically close to species’ hot limits (red; n = 969 sites), cold limits (blue; n = 2244 sites), and the middle of their observed climatic limits (purple; n = 11,793 sites). Rug plots show the distribution of observations. Confidence intervals (±95%) are shown around linear trendlines.

More text:

Bumble bee species richness declined in areas where increasing frequencies of climatic conditions exceed species’ historically observed tolerances in both Europe and North America. An analysis of covariance that modeled the response of detection-corrected richness to community-averaged measures of climatic position revealed that, consistent with observed trends in species-specific occupancy change, richness was more likely to decline in regions experiencing warming, especially when species present were in the warmest parts of their historical ranges (table S2)...

...Projections suggest that recent climate change has driven stronger and more widespread bumble bee declines than have been reported previously, especially in Europe (Fig. 4). European estimates of observed richness rely particularly on observations from well-sampled regions that were cooler in the baseline period and that have experienced less warming subsequently (9), which may have contributed to underestimation of recent species richness decline across that continent (figs. S6B, S9, and S10). These findings contrast with those for other taxa that predict widespread range expansions and increasing species richness toward warming environments in the north (13, 14).

Figure 4:

The caption:

Fig. 4 Climate change–related change in bumble bee species richness from a baseline (1901–1974) to a recent period (2000–2014).

Predictions are from a model projecting percent change in detection-corrected bumble bee species richness as a function of mean community-averaged thermal and precipitation position.

Some concluding remarks from the paper:

Climate is expected to warm rapidly in the future (20). Using a spatially explicit method of measuring climatic position and its change over time, we show that risks of bumble bee extirpation rise in areas where local temperatures more frequently exceed species’ historical tolerances, whereas colonization probabilities in other areas rise as climate changes cause conditions to more frequently fall within species’ thermal limits. Nevertheless, overall rates of climate change–related extirpation among species greatly exceed those of colonization, contributing to pronounced bumble bee species declines across both Europe and North America with unknown consequences for the provision of ecosystem services. Mitigating climate change–driven extinction risk among bumble bees requires efforts to manage habitats to reduce exposure to the growing frequency of temperatures that are extreme relative to species’ historical tolerances.

The bold is mine.

...efforts to manage habitats...

Don't worry. Be happy. It's not your problem, those bumblebees. Transitional gas...solar roof...wind turbine...Elon Musk...Your SpaceX ticket to Mars...not your problem...you're for all of it. aren't you?.

You know what? Some of those bumble bees are nasty anyway. They can sting you. Some of them are boring insects and they can drill holes in the wood in your deck from which you can admire the view, and cost you thousands of dollars, way more than $2/day.

...efforts to manage habitats...

The whole world is a habitat.

I am a member of that awful Baby Boomer generation. When we were kids we used to huddle in front of black and white televisions with tiny screens and watch those Japanese monster movies - "science" fiction - where all the world's political leaders would call upon the world's scientists - who were always deeply respected and whose advice was always taken.

I actually used to believe the world worked like that, but then again, I was eight years old and now we are all eight years old, in a very different world.

Don't worry. Be happy.

History will not forgive us, nor should it.

TGIF tomorrow. Enjoy it.

Electrochemical Molecular Switches for the Capture and Release of Uranium.

The paper I'll discuss in this post is this one: Redox-switchable carboranes for uranium capture and release (Gabriel Ménard et al, Nature volume 577, pages 652–655(2020))

According to a DOE report, DOE/EM-0275 as of 1996, the US government had in stock about 585 million kg of depleted uranium, beyond the 25 million kg enriched to about 3% in U-235, about 610 million kg.

A kg of plutonium, the starting material for which is depleted uranium, contains about 80.3 trillion joules of energy, completely fissioned.

The world was, as of 2018, consuming about 600 exajoules (600 million trillion joules) of energy each year.

Recently there have been efforts by a number of companies, one of the most well known being Bill Gates' Terrapower, to commercialize "breed and burn" type reactors that transmute depleted uranium into plutonium in situ.

It follows that this US inventory is sufficient, at current levels of energy demand to power all the world's energy for about 80 years, no dangerous natural gas, no dangerous petroleum, no coal mining for energy purposes. Of course, there are other uranium inventories elsewhere in the world. In addition, a side product of the useless wind industry and the electric car industry, both of which depend on access to iron neodymium boride magnets, often doped with dysprosium - lanthanides - is the radioactive element thorium. Collected from lanthanide mile tailings, dumps, in which the thorium has been partially refined, this thorium is also a valuable nuclear fuel. It is reasonable to say that in a "breed and burn" powered world it would be unnecessary to mine any fuels for several centuries.

Fracked rock, which has been eternally pulverized for a few decades of "good times" by all of us self declared "green" people also represents a potential source of uranium: The radon dumped by the gas industry in Pennsylvania's Reading Pronge gas fields indicates that this pulverized rock, over which water may flow for millenia upon millenia, is also a potential uranium source.

Finally, since that establishment of oxygen in the planetary atmosphere, a continuous uranium cycle has been established in the planetary oceans; they contain about 4.5 - 5 billion tons of uranium.

There has much discussion of refining uranium from dilute sources, seawater, run-off from uranium mine tailings, and natural uranium formations both for the purposes of obtaining fuel as well as to remediate areas of anthropomorphic contamination or natural uranium flows. Uranium is a chemotoxic element, notably having effects on renal and other tissues. Many thousands of papers on this subject have been published in the scientific literature; I almost certainly have hundreds in my personal electronic files. Many of these papers concern organic resins, notably amidoxime functionalized resins. There are also inorganic species that have been advanced for this purpose. What is of interest about this laboratory scale material is that it can more or less breathe uranium, in effect "inhale" and "exhale" it by the application of electrical currents.

From the introduction:

Known for over 50 years, carboranes have been extensively studied in coordination chemistry (including with U), catalysis, luminescence, and energy storage applications10,11,12,13,14,15. Studies have shown that reduction of substituted closo-carboranes to the nido-carboranes results in rupture of the C–C bond and cage opening, with a simultaneous increase in ligand bite angle, θ (Fig. 1a; closo and nido refer to 2n + 2 and 2n + 4 framework bonding electrons, respectively, where n is the number of vertices)11,14,16,17,18. We rationalized that by incorporating donating groups to ortho-carborane, we could tune the chelating properties of the cluster switching from opened to closed conformations by redox control of the reduced and oxidized states, respectively, and enable the chemical or electrochemical capture and release of uranyl in solution (Fig. 1a).

Closo and nido refer to something known as the "Wade-Mingo" rules, and refer to the presence of a complete platonic solid structure, in this case icosahedral symmetry, having all vertices represented, closo or one vertex missing, nido. (The symmetry of in these cases is not truly icosahedral, since the symmetry is "disturbed" or "degraded" by the presence of the functionalized carbon. The carbon in this boron hydride structure is functionalized with diphenylphosphine oxide.

Figure 1:

The caption:

a, General chemical or electrochemical mono- or bi-phasic capture of uranyl from UO2X2L2 (X = Cl−, OAc−; L = THF, Ph3PO) using the reduced ‘open’-cage nido-carboranes (2a/2b) generated by reduction (for example, CoCp∗2CoCp2∗ or negative bias) of the ‘closed’-cage closo-carborane (1). The corresponding relative bite angles (θ are also shown. Oxidation (for example, [FeCp2][PF6] or positive bias) of the captured products 3/4 or 3N/4N leads to UO22+ release. Compounds labelled in green have been chemically isolated, whereas compounds in orange are proposed electrochemical products (see Methods). Blue and red pathways represent UO22+ capture and release, respectively. b, c, Solid-state molecular structures of 4 (b) and 3 (c) obtained from XRD studies. H atoms, [CoCp∗2]+[CoCp2∗]+ counter cations, phenyl C–H linkages and all co-crystallized solvent molecules are omitted for clarity. See Extended Data Fig. 1for the structures of 1 and 2a.

Many of the experiments described in the full paper take place in organic solvents, which of course, is not seawater, but nevertheless the system is definitely quite interesting, and one can imagine modifications.

Anyway, the system operates electrochemically.

Figure 2:

The caption:

a, Illustration of the H-cell used, incorporating excess Fc/Fc+ (left) and 1, TPO and [UO2Cl2(THF)2]2 (right) in a 3:1 PC:benzene solvent mixture. Charging the cell (blue) leads to the capture of UO22+, converting 1 to 4N (major product) and 3N (minor product, not shown). b, Quantification of products and reactants by 31P{1H} NMR spectroscopy against an inert internal standard, [Ph3PNPPh3][PF6] (not shown). The initial spectrum is shown in grey, whereas spectra acquired during charge and discharge cycles (1–6) are shown in blue and red, respectively. c, Bottom, applied galvanostatic potentials for charge (blue) and discharge (red) cycles. Dashed lines represent wait periods, which were necessary for 31P{1H} NMR data acquisition. Each cycle is 24 h. Top, instrumental measure of delivered charge (teal) versus charge used for the reduction of 1, measured by quantifying the total reduced products, 3N and 4N, by 31P NMR spectroscopy. See Methods and Extended Data Figs. 6, 8 for additional experimental details and data.

The issue of organic solvents is addressed as shown in figure 3, which essentially is an extraction procedure.

Figure 3:

The caption:

Fig. 3: Simplified depiction of half H-cell and spectroscopic measurements for the biphasic electrochemical capture/release of dissolved UO22+ (yellow sphere) from/to buffered aqueous solutions. See Methods and Extended Data Fig. 7 for an expanded stepwise figure and all experimental details. a, Biphasic mixture of UO2X2 dissolved in a NaOAc-buffered aqueous solution (pH 5.4) and of electrochemically generated 2bfrom 1 (X = OAc− or NO3−. Inset, aqueous UV-Vis and organic 31P{1H} NMR spectra after reduction of 1 to 2b, but before phase mixing. Residual 1 is observed in the latter owing to the set SOC. b, Simplified depiction of the captured UO2X2 in the form of 3N and/or 4N. Inset, aqueous UV-Vis spectrum showing the capture of UO2X2 by the 2b/DCE layer (top); the corresponding 31P{1H} NMR spectrum of the DCE layer showing the captured major product (3N/4N) and minor residual 1 (bottom). c, Biphasic release of UO2X2 from the DCE layer to a fresh NaOAc-buffered solution (pH 5.4), following electrochemical oxidation of 3N/4N. Inset, aqueous UV-Vis and organic 31P{1H} NMR spectra of free UO2X2 and 1, respectively—both consistent with the release of captured UO2X2 from the DCE to the aqueous phase. A small amount (~20%) of unknown byproducts (marked by asterisks) is also observed in the 31P{1H} NMR spectrum.

Note that exposure to organic solvents would not be acceptable unless the organics were destroyed by subsequent processing. One such available approach to processing would involve subjecting the resultant aqueous solution to supercritical conditions, whereupon the solvent residues would be oxidized to carbon dioxide and the water reduced to hydrogen.

This is a lab scale procedure, and it seems to me that a number of issues need to be addressed before anything like this could be run on an industrial scale. Then again, as stated at the outset, the "breed and burn" concept means that there is really no need to obtain more uranium than has already been mined, at least for several centuries, so there's plenty of time to do that, to make nuclear energy essentially inexhaustible. (At the end of my life, it does seem that ultimately fusion energy may be viable, but current isolated uranium might make the world survivable in the interim.

It's a nice little interesting paper, I think.

Have a nice day tomorrow.

My wife made me watch a wonderful movie with her yesterday.

My wife loves movies; I'm sort of "so-so" on watching movies; I generally refuse to watch horror movies, disaster movies, and the like.

(My wife likes to watch movies that put her to sleep, at least after the sixth or seventh time she's seen them. It's a joke in our family.)

We had some rare time alone together to enjoy one another yesterday, and she insisted I watch a movie with her, a romantic comedy.

It was a wonderful film, touching in a fairly profound way on the cultural clashes that can take place in immigrant communities with the American culture. (My father-in-law experienced this as he was first generation Italian American, something that had effects on my marriage to a second generation half Italian American.)

This film was particularly poignant because it was made before the age of the racist idiot "pResident" in the White House, because the immigrant culture in question was Islamic, Pakistani in fact.

It was a very sweet and in someways profound romantic comedy. It is also a true story, and if you watch it on DVD it is definitely worth watching the extra features.

This is the movie in question:

The Big Sick

The biggest star in it is Holly Hunter, and she does an outstanding job. In the role she plays, mother of the native American in the love object in the film, her character is also dealing with a cultural clash in her marriage, a clash between a right wing North Carolina culture with the New York culture of her husband.

A lovely film.

Separation of Three Phases, Gas, Liquid and Solid Using a Cyclone Injected with Hot Hydrogen.

The paper I'll discuss in this post is this one: Hydrocyclone Settler (HCS) with Internal Hydrogen Injection: Measure of Internal Circulation and Separation Efficiencies of a Three-Phase Flow (Roberto Galiasso Tailleur, Andres G. Peretti, Ind. Eng. Chem. Res. 2020, 59, 3, 1261-1276) Dr. Tailleur is a Chemical Engineer whose affiliation in the paper is listed as Simon Bolivar University in Miranda Venezuela. Venezuela, for those who do not know, is a large producer of the dangerous fossil fuel petroleum, which is toxic in not only environmental and epidemiological sense, but is also toxic in an economic and political sense. This has certainly been true in Venezuela. Venezuela is a case in point that political and economic absolutism on the far left is not particularly less odious and less destructive than political and economic absolutism on the right. The main product of the country these days is economic refugees.

This paper is about the processing of dangerous fossil fuels, and concerns the catalytic alkylation of C2 and C3 alkenes, ethylene and propene, with isobutane, presumably to make the dangerous fuel gasoline.

As an opponent of the use dangerous fossil fuels, on the grounds that they are destroying a future that does not belong to us, that it is not our right to destroy, it may seem strange that I am as interested as I am in this kind of technology. Nevertheless I have been recently emphasizing that many of the technologies in industries that should be abandoned on the grounds they are not sustainable, have use in other industries, or in new uses for expansion of applications of extant industries. Indeed this was historically true of the dangerous petroleum industry. The original purpose for the distillation of dangerous petroleum which was industrially pioneered by John D. Rockefeller, was to make lamp oil to replace whale oil as the over hunting of whales was leading to the decline of the species that had nothing to do intrinsically with pollution, making whale oil expensive and difficult to obtain. The development of the distillation process led to a search for what was then a by product of distillation, gasoline. The destruction of the planetary atmosphere followed in the following century and a half.

I have been making this point as well about the useless solar thermal industry, another so called "renewable energy" industry dependent upon turning huge pristine ecosystems into industrial parks that have low capacity utilization, in this case desert ecosystems. The solar thermal industry will never be able to make economically viable hydrogen to replace the source of more than 98% of the current source of the world's hydrogen, dangerous natural gas and dangerous coal, but the technologies explored in papers around thermochemical water and carbon dioxide splitting cycles that are often described in papers as being applicable to solar thermal technology are equally viable to sustainable and low environmental impact nuclear systems.

According to the reference in the paper, the compounds in the three phases described in this paper for which this hydrocyclone was developed are as follows: The solid is a platinum sulfate-titanium-zirconium catalyst supported on silica, SiO2, basically sand. The gases are isobutane, propene and butene, as described above, and the liquid is the condensate, dangerous alkanes that are components of dangerous gasoline.

Be this as it may, I am always thinking about ways that future generations will clean up the mess that our generation produced in a kind of drunken sybaritic ecstasy of material consumption, albeit the ecstasy in question being distributed among parties in an ever less judicious way.

The biggest mess we leave of course, is a destroyed atmosphere. Among the engineering routes to removing the dangerous fossil fuel waste carbon dioxide from the atmosphere, all of which will be challenging, I personally regard reformation of biomass with supercritical water, supercritical seawater, or supercritical carbon dioxide to be potentially viable routes. These technologies will involve three phase (actually four phase) separations, and thus my interest in the technology. Many, most, if not all, will involve hot hydrogen.

From the introduction of the paper:

Figure 1 shows the new alkylation–regeneration process scheme that is described in detail in refs (1) and (2); it consists of a slurry transport reactor (STR, used for alkylation), two stages of gas–solid–liquid separation in a hydrocyclone stripper (HCS1 and HCS2), and a fluidized bed reactor (FBR, employed for catalyst regeneration). The HCS of Figure 1 is used to separate gases, liquids, and solids from the stream that left the alkylation reactor at 360 K and 1.4 MPa. It delivers solids to the FBR and gases and liquids to other separation stages.(1) The solid obtained (spent alkylation catalyst) in the two HCS stages must be stripped of adsorbed hydrocarbons by hot hydrogen before being fed to a fluidized bed catalyst regenerator. Ninety-five percent of the regenerated catalyst is sent back to the STR. Catalyst purge and make up is a function of catalyst deactivation, HCS efficiency, and fines produced in the process.

Figure 1:

The caption:

Figure 1. Hydrocyclone–settler system.

The introduction continues:

The feed of the HCS is composed of hydrogen soluble in light alkylate and 8% by weight of the catalyst; the latter contains less than 2% of 1–10 μm and more than 97% of 40–60 μm in particle diameter. More than 98% of the solids and less than 10% of liquids must be recovered at the underflow (UF) stream. In this process scheme, two stages are used to obtain the maximum recovery of solids and liquids and deliver preheated solids into the regenerator (Figure 1).
Hydrocyclones have been successfully used in the industrial separation of solids for more than 40 years. The design is simple, easy to operate, and of low operating and maintenance costs; these devices are very important to perform solid separations; nevertheless, high solid efficiency in hydrocyclones is difficult to achieve when there are small differences between liquid and solid densities in the feed and they contain very fine particles. In conventional (isothermal) liquid–solid separation, the average cut size dp50 is related to the inlet pressure at an order of 0.25 and to the hydrocyclone diameter, according to Bradley(2) and Rietema(3) equations...

...Previous experiments with a small hydrocyclone and the study done for the spouted bed reactor development were used to select current base case (BC) dimensions and operating conditions for the new hydrocyclone settler (HCS1). Then, the HCS1 was tested to mainly explore the effect of lower cone lengths, feed and hydrogen flow rates, and temperatures using five types of sensors: ECT, differential pressure, pressure, and temperature as well as by sampling. In addition, other amounts and particle size distributions were used to compare with BC. These sensors were calibrated using a well-known flow vessel at similar operating conditions to those of the HCS; data were consolidated, and the methodology was used in the current study of HCS1.
There are several characteristics of this device that are not mentioned in the literature about conventional three-phase cyclones:

(1) radial and axial gas, liquid, and solid heating by hot hydrogen,

(2) vaporization of hydrocarbons,

(3) slurry lift in the riser by effects of hydrogen injection through a nozzle,

(4) tangential and axial flows of gases in the riser that have a divergent outlet,

(5) different types of gas cores (formed hydrogen plus vaporized hydrocarbons),

(6) gas core positions controlled by the settler level of wet solids,

(7) tailpipe discharge into a settler with controlled levels of solids, and

(8) use of high-pressure metallic hydrocyclones with the flow, level, and pressure controlled by three automatic loops.

The main objective of this device is to maximize the separation of coarse (>10 microns) and minimize that of fines particles (<10 microns) and liquids going into the regenerator operating at a 1.4 MPa inlet pressure; a secondary objective is to preheat the catalyst for regeneration in the fluidized bed, and the third one is to minimize the delta of pressure, erosion, vibration, and pressure oscillation in a steady-state operation.

The streams were characterized by their particle size distribution, pressure, temperature, amount and type of solids, and gas and liquid content. Gas–liquid equilibria were calculated using the Peng–Robinson state equation.

More than 1800 experimental points were used to calibrate the sensors. The results are reported in the Supporting Information. A total of 2800 points were obtained with HCS1 using nine high-pressure prototypes. The separation efficiencies and internal circulation were measured, and the results were compared to the values predicted by known published equations.

(Yesterday I attended a wonderful lecture, in the context of the development of understanding fusion plasmas, on the use of "artificial intelligence" in the processing and weighting of fairly extreme multivariate analytical inputs, which I might imagine would have application for a system of measurements for this dangerous fossil fuel technology. It was unbelievably fascinating. It may be available as a video at the above link in a few weeks.)

Figure 2 in the paper shows the types of analytical tools used in the analysis of this device:

The caption:

Figure 2. (a) Global scheme of slurry preparation and HCS1 and HSC2 with secondary hydrogen preheating and injection at the inlet of riser. (b) Five ECT sensors located in the cone with capacitance, temperature, and pressure detectors and an imaging processor system; (c) hydrocylone dimensions; and (d) list of sensors (see location in (a)) connected to a data logger and processing computer.

Figure 3 shows the types of readouts being processed:

The caption:

Figure 3. Different variables plotted as functions of operational time (minutes). Upper part: inlet feed and hydrogen mass flow rates. Middle part: delta of pressure and gas temperatures at the outlet. Lower part: slurry mas flow rates at the UF and OVF streams. HCS1 at base-case operating conditions.

(These inputs are considerably of lower dimensionality than the measurements of fusion plasma devices, but depending on the time resolution can still be quite complex.)

Two tables describing the inputs and dimensions of the pilot device:

Some overview remarks of the conduct of experiments:

The pilot plant was continuously operated, and the flow rate, temperature, vibration, and pressure were recorded (Figure 3); mass balances were performed every 10 min. The results are reported in Table3 as an example. Internal circulation obtained by the sensors is shown in Figure 4, and the radial profiles of pressure, temperature, and solid content are in Figure 5. The flow in the apex and tail pipe is depicted in Figures 6 and 7, and the effect of apex and vortex finder diameters is in Figure 8.

Table 3:

The figures:

The caption:

Figure 4. (a) Half-HCS1 with the spires going downward (yellow) by the wall and going upward (green) around the gas core. (b) Radial distribution of solids (ECT) at z = 0.5 and z = 0. (c) Profiles of temperature (red), vaporization (purple), solid concentrations (green), and pressure near the external wall. (d) PSD in the feed and OVF and UF streams (%, with respect to the stream).

The caption:

Figure 5. (a) Radial profile of temperature (red, thermocouple) and the core radius (yellow, ECT); (b) radial distribution of pressure; (c) radial distribution of delta pressure; and (d) ECT measure of solid distribution. Operating conditions for HCS1: FH2 = 0.4 kg/s, TH2 = 560 K, Lc1 = 0.5 m, uo1 = 4 m/s, Lc1 = 0.4 m, and Do/Dc = 0.4.

The caption:

Figure 6. (a, b) ECT spaced by 8 cm in the connecting (tail) pipe during circulation (circ) and spray modes of discharge. (c) Twin-plane Cs/Cs,av ratio measured by ECTV as a function of delay time for circulating and circulating-spray-circulating types of discharge in the tail pipe.

The caption:

Figure 7. Effect of hydrogen in the oscillation of the core and frequency of circ and circ-spray-circ mode of solid discharge. (a) ECT at z = 0.5 and z = 0 as a function of time; (b) amplitude of the vibration at the apex (10 kHz) as a function of time.

The caption:

Figure 8. Effect of Du and Dr in coarse solid separation efficiency at optimal hydrogen flow rates. Delta of pressure of vortex–apex of −4 ± 0.5 kPa and vibration frequency of 20 ± 4 Hz.

The caption:

Figure 9. (a) Effect of PSD in the feed in solid distributions at the outlet streams. Feed A (black dashed lines), UF (red dashed lines), and OVF (green dashed lines). Feed B (violet dashed lines), UF (gray dashed lines), and OVF (blue dashed lines). (b) 2D ECD image of radial particle distribution at z = 0.5 for A and B solid distributions in the feed. (HCS1 base-case dimensions and operating conditions.)

Some discussion of the results:

The main difference between HCS1 and previous hydrocyclone technology is the use of hot hydrogen that “complements” the effects of centrifugal force in the separations of gas, liquid, and solid from the stream that leaves the alkylation reactor. Both liquid and solid separations (efficiencies) need to be maximized because they affect the economy of the process.
Sensors (ECT, differential of pressure, pressure, and temperature) and sampling allow determining the flow pattern of solids in different areas of the hydrocyclone. The tests found that hydrogen produces a different type of fluid circulation in the lower cone, riser, and apex than that reported for conventional hydrocyclone, desander, and deoiling devices. Hydrogen produced important hydrocarbon vaporization that changes slurry properties (density and viscosity), radial and axial distributions of solids, temperature, and delta of pressure and produces a carry-over of slurry through the riser. Hydrogen injection is responsible for pressure oscillation and additional vibration of the HCS.

The simulation of HCS1 using published correlations show important deviation. For example, the calculation presents a deviation higher than 38% in the prediction of for HCS1 operating with cold hydrogen (363 K and 1.4 MPa), but the differences are higher when using hot (530 K) hydrogen. Reynolds numbers of the feed (inlet), required to produce high solid/liquid separation at the apex in HCS, are half those measured by other authors in isothermal hydrocyclones (see, for example, the value used by Wang and Yu(30)); these authors observed a shorter reverse core in flooded hydrocyclones at almost twice the inlet Re number needed for solid separation than that calculated for the isothermal HCS1 device. The HCS operates at a relatively low inlet Re number with a shorter cone and broader vortex finder and underflow diameters than those of conventional isothermal hydrocyclones. There is no correlation between d50 and the inlet Re number as it was for conventional devices (see Gu and Liow(39)).

An excerpt of the authors conclusions:

A total of 2800 experimental points have been obtained for HCS1 to determine the best dimensions and operating conditions for gas, solid, and liquid separation. Stability, efficiency, delta of pressure, catalyst attrition, and the effect of hydrogen flow and temperature were studied using BC dimensions, selected based on previous studies; the effect of some critical dimensions were studied by departing from BC. The objectives of the separations are imposed by the economy of the process. Minimum vibration and pressure fluctuations and pressure losses are operational requirements. The results demonstrate that

(1) the solid separation efficiency increases sharply from fines (0–10 microns) to coarse particles (40–70 microns) as expected. The efficiency for fine-particle separation is higher than that observed in conventional hydrocyclones.

(2) The solid separation mainly occurred in the shorter than conventional lower cone where coarse particle tangential and radial velocities are accelerated by centrifugal forces and hydrocarbon vaporization. There is a nonlineal radial profile of temperature, pressure, and solid concentration across and along the lower cone. Without hot hydrogen injection, there is not enough centrifugal forces to separate solid and liquid for BC dimensions.

(3) In steady-state conditions, the slurry, high-in-solid, moves downward, rotating against the internal wall in the lower cone, axis, and tail pipe. The level of solids at the settler ropes the discharge and induces the upward movement of low-in-solid slurry that helps the separation at the apex and seals the bottom of the gas core...

Additional points are made in the conclusion, and the paper features extensive discussion of these engineering parameters.

These sorts of things, I know, are very esoteric, but these are the types of things about which future generations will need to know to address the consequences our irresponsibility.

Enjoy your Sunday.

Absorption of Sulfur Dioxide by Deep Eutectic Solvents

The paper I will discuss in this post is this one: Role of Hydrophilic Ammonium-Based Deep Eutectic Solvents in SO2 Absorption (Duan et al Energy Fuels 2020, 34, 1, 74-81.)

All of the waste products resulting from the combustion of dangerous fossil fuels are harmful, the most serious of course being carbon dioxide over the long term, but in terms of immediate health consequences, the carcinogens found in particulates are probably responsible for the majority of the millions of deaths dangerous fossil fuel waste each year. This said, none of the other pollutants are harmless. I sometimes muse to myself whether the largest source of mercury exposure, the combustion of coal, is responsible for the rising popularity of stupidity. As many educated people know, the madness of "Mad Hatters" - which was very real and not merely a literary invention - was the result of the use, by hatters, in the 18th and 19th century, of mercury to improve the appearance of hat pins.

Mercury, since the days of "mad hatters" was further distributed by distributed medical waste in thermometers and blood pressure devices, laboratory use in anemometers and other devices - including the device used by the first American to win the Nobel Prize in Physics, Albert Michelson, who showed that the speed of light was not subject to relativistic enhancement by the speed of the Earth's revolution around the sun, inspiring Albert Einstein's famous theory on this subject. It is still also widely used in gold mining operations, which is also represents, both in abandoned and operative gold mines, a serious source of mercury pollution.

However, the combustion of coal is still the major source of mercury pollution. Despite all the popularly believed rhetoric that "coal is dead," especially when it is raised as "proof" on an absurd but widely held belief that so called "renewable energy" is great, as I often note, in this century, coal has been the fastest growing source of energy on this planet, by far, followed by dangerous natural gas, followed by petroleum. The use of dangerous fossil fuels is rising and is doing so rapidly. If you think we are either doing something or going to do something about this state of affairs, sorry, you are lying to yourself.

Another major pollutant, probably dwarfed by particulates and heavy metals - not limited to mercury but also including the other major neurotoxin lead, and the element that is the subject of much mysticism, uranium - release by the combustion of coal consists of the two oxides of sulfur, SO2 and SO3, sulfur dioxide and sulfur trioxide. The latter is the anhydride of sulfuric acid. In the presence of water, it forms sulfuric acid, which is now a constituent of clouds where it leads to acid rain (along with nitrogen oxides).

This paper is about sulfur dioxide.

I favor the immediate phase out of dangerous fossil fuels - not by using so called "renewable energy" which will remain, as it always has, spectacularly incapable of addressing any major environmental problem since it is neither sustainable nor safe nor clean, but by the form of energy that many people, regrettably some Presidential candidates who wish to be thought of as being "green," nuclear energy. The idea of phasing out nuclear energy, as opposed to rapidly expanding it on an emergency basis, is definitely in mad hatter territory. Indeed, my speculation about the effect of mercury and lead aerosols released by dangerous fossil fuel combustion as having a bearing on the mass insanity that is on the rise, everywhere, is driven a consideration by the popular insanity with respect to nuclear energy, among many other things. Nuclear energy is not risk free, but it doesn't need to be risk free to save lives overall. The situation is best described by the existence of ambulances. Ambulances travel at high and potentially dangerous speeds, ignoring traffic laws, and, as the operate, releasing deadly dangerous fossil fuel wastes from their tailpipes. However the existence of ambulances has clearly saved more lives than it has cost, and so, rightly, we accept the existence of ambulances, even knowing that they are potentially very dangerous devices.

Ambulance Safety NHTSB Infographic.

Shutting perfectly operable nuclear power plants kills people; this is true in Germany; it is true in California, Massachusetts and Vermont. It is true anywhere nuclear power plants are shut by appeals to fear and ignorance.

To return almost to the point, and get off my continuously mounted soapbox, the paper listed above is very much about the continued use of coal, and is a description of putting lipstick on the expanding coal pig, by offering a route to reducing just one of the pollutants, not even the most important pollutants. Along with so called "renewable energy" which is also lipstick on the coal, petroleum and gas pig, there is no technology that can make fossil fuels acceptably safe, especially because nuclear energy is now so well understood, and neither fossil fuels, or reactionary rhetoric about so called "renewable energy" can make any technology as safe and as sustainable as nuclear energy.

Nevertheless, it is well worth considering this paper even if one is an environmentalist who favors the immediate phase out of all dangerous fossil fuels. Here's why: Because we hate our children so much as to insist them to enslave themselves to clean up our mess, because we have done exactly zero beyond issuing well meaning platitudes to address climate change, it will be necessary for future generations to remove carbon dioxide from the air. The engineering of this task is extremely challenging, extremely expensive, and very energy intensive. The largest source of so called "renewable energy" - biomass - is currently the second largest, after dangerous fossil fuels - cause of energy related deaths, the majority of which are currently involved in air pollution, although extreme weather is catching up.

However, one thing that biomass does, as it is self replicating and can more or less spontaneously cover huge surface areas cheaply, and because it has evolved to a combinatorially optimized point over billions of years, is to concentrate carbon from the atmosphere. Recently in this space, citing a paper on an issue in biomass closed (smokestack free) combustion, corrosion, I pointed out that sulfur is an essential element in living systems. Thus the treatment of biomass to recover the carbon in it will necessary involve sulfur, either in the extremely reduced (and highly toxic) form as H2S gas, or as sulfur oxides.

In addition, as I noted in passing, one widely discussed thermochemical cycle for splitting water is the sulfur iodine cycle. In the oxygen generating portion of this cycle, only 33% of the evolved gases after the condensation of water is oxygen. 67% is sulfur dioxide. I stopped thinking about the sulfur-iodine cycle a few years back because of mass transfer issues, but recently, having been exposed indirectly to new insights, I'm thinking about it again, and thus this paper, which is about the separation of sulfur dioxide from a gas stream - in this case flue waste - is of some interest to me, which is not to say that I think that the sulfur iodine cycle is the best thermochemical cycle - I actually favor Allam cycle coupled metal based carbon dioxide splitting cycles - but it is nonetheless worth considering. I recall reading a few years back that the Chinese were working on piloting this cycle with nuclear energy, but having (temporarily) lost interest, I didn't follow up to see if this actually happened.

Anyway, from the introductory text of the paper:

The emission of sulfur dioxide (SO2), mainly from the burning of fossil fuels, has caused serious environmental problems.(1) The development of renewable and efficient absorbents for the removal and recovery of SO2 is important for our society. In the field of SO2 absorption, the conventional absorbents, including CaCO3, limestone, and NH3, can potentially cause severe pollution. In addition, the technologies to remove acid gases have high operation costs and energy requirements.(2,3) The absorption of SO2 requires greener and more efficient solvents.(4)

Ionic liquids (ILs) have been applied in SO2 absorption. In particular, imidazolium-based ILs are excellent for SO2 absorption.(5,6) Hong found that the ability to absorb SO2 was related to the numbers of ether groups on ILs, as the ether-functional group could enhance the physical reaction between SO2and ILs. [E8min][MeSO3] could absorb 6.30 mol SO2 g–1 ILs at 30 °C and under atmospheric pressure.(7) Lee et al. reported the absorbing behavior of [Bztmeda][MeSO3].(8) However, with further investigation, the toxic and recalcitrant ILs could arguably cause environmental damage.(9) Deep eutectic solvents (DESs), as a new kind of greener and cost-efficient solvents, have been used widely in gas separation.(10−13) Han et al. synthesized choline chloride (ChCl)-based DESs and reported that ChCl/glycol, ChCl/glycerin, and ChCl/hexamethylene glycol could successfully absorb SO2. The absorption ability increased with the concentration of ChCl and could reach 0.678 g SO2g–1 DESs.(14) Deng prepared ChCl/levulinic acid and applied it for SO2absorption. With the calculated absorption enthalpy, the thermodynamic properties were investigated.(15) Liu investigated the absorption capacity of phenol-based DESs for SO2 at 293.15–323.15 K and 0–1.0 bar, reaching the capacity of 0.528 g SO2 g–1 DES.(16) Hydrophilic DESs have been a promising SO2 absorbent. However, the high viscosity is one of the significant characteristics of DESs. For example, the viscosity of ChCl-based DESs is usually higher than 2000 mPa·s.(17,18) This viscosity creates a mass-transfer barrier in the gas–liquid (SO2–absorbent) reaction, and thus, SO2 absorption is greatly limited.(19)
To investigate the mass-transfer barrier in SO2 absorption, a kind of hydrophilic deep eutectic solvents (DESs) and their hydrates were prepared to solve the relatively viscosity of DESs in SO2 absorption. The effects of tetrabutylammonium halogen/caprolactam (TBAB/CPL) DESs were investigated systematically, and the hydrophilic interfacial reaction was studied to explore the absorption mechanism of SO2 absorption in DESs.

A deep eutectic solvent is a solvent that has a lower melting point - a melting point lower than its individual components in the absence of the others - than "ambient temperatures, generally taken to be 25°C.

The rest of the story can be pretty much appreciated merely by looking at the pictures and their captions:

The caption:

Figure 1. Effect of the proportion of TBAB and CPL on SO2 absorption at 20 °C under atmospheric pressure.

The caption:

Figure 2. SO2 absorption of TBAB/CPL DESs as a function of temperature under atmospheric pressure (molar ratio of 1:2).

The caption:

Figure 2. SO2 absorption of TBAB/CPL DESs as a function of temperature under atmospheric pressure (molar ratio of 1:2).

The caption:

Figure 4. Arrhenius fitted curves of ln η vs 1/T for TBAB/CPL DESs.

The caption:

Figure 5. SO2 absorption of TBAB/CPL DESs and TBAB/CPL aqueous solutions as a function of DES concentration under atmospheric pressure (molar ratio of 1:2, 20 °C).

The caption:

Figure 6. Surface tension of TBAB/CPL DES aqueous solutions before absorption of SO2 (molar ratio of 1:2, 20 °C).

There is considerable discussion in the paper on the properties of the interface, to which the above graphic alludes. The interface is, of course, an important issue in gas absorption, as further explored in the text referring to the next graphic:

The caption:

Figure 7. Surface tension of TBAB/CPL DES aqueous solutions after absorption of SO2 (molar ratio of 1:2, 20 °C).

The caption:

Figure 8. Ea of TBAB/CPL DES aqueous solutions at different concentrations before absorption of SO2(molar ratio of 1:2, 20 °C).

The caption:

Figure 9. Ea of TBAB/CPL DES aqueous solutions at different concentrations after absorption of SO2(molar ratio of 1:2, 20 °C).

It may be useful for anyone who may wish to explore this conception further, to give some commentary on spectra and mechanism.

Some of the remarks on spectra:

The FTIR and in situ IR spectra of TBAB/CPL DESs and TBAB/CPL DES aqueous solutions (TBAB/CPL DESs, molar ratio of 1:2, 2 mol L–1) before and after absorption of SO2 are shown in Figures 10 and 11, respectively. Before absorption of SO2, the peak at a wavelength of 3401.3 cm–1 denotes the N–H stretching vibration of the TBAB/CPL and the peaks at approximately 1635.4 cm–1 represent the C═O stretching vibration. For the N–C–H stretching vibration in TBAB/CPL, the absorbance peak is found at 1477.2 cm–1.(28)(28)However, the characteristic peaks of TBAB/CPL are all changed or shifted after absorption of SO2. The N–H stretching vibration of the TBAB/CPL shifts to 3216.7 cm–1, the new C═O stretching vibration appears at the peak of 1646.9 cm–1, and a slight blue shift occurs for the N–C–H stretching vibration. In addition, some new characteristic peaks are shown in the FTIR spectra of TBAB/CPL after absorption of SO2. The S═O stretching vibration can be observed from 1033.5 to 1083.8 cm–1. The symmetric and asymmetric stretching modes of the absorbed SO2 can be observed clearly at 1353.8 cm–1 (Figure 10a). The SO2 absorption process is monitored with in situ IR spectroscopy (Figure 10b,c). The spectra exhibit two obvious vibration changes (the enlarged views of Figure 10d,e). The characteristic peaks of S═O, C═O, and N–H all increase gradually as the process goes. These changes in Figure 10 demonstrate that the interaction of SO2 and TBAB/CPL DESs occurs, which means the formation of hydrogen bond of C–C═O–N···H···SO, a similar hydrogen bond is also found in the previous work.(29)

The caption:

Figure 10. In situ IR and FTIR spectra of TBAB/CPL before and after SO2absorption (TBAB/CPL, 2 mol L–1, 20 °C).

Figure 11. In situ IR spectra of TBAB/CPL aqueous solution before and after SO2 absorption (TBAB/CPL, 2 mol L–1, 20 °C).

Some remarks in the paper on mechanism:

...Based on studies on the interfacial properties, the absorption mechanism of SO2 in hydrophilic DESs could be proposed as Scheme 1. The H–N–C═O bond of CPL forms an intermolarcular hydrogen bond with Br– of TBAB, forming a complex of H–N–C═O···Br. Meanwhile, the hydrogen-donor group in water (H) would react with the hydrogen-acceptor group in CPL (C═O) to form the TBAB/CPL DES hydrates. In the process of SO2 absorption, the polar SO2would react with TBAB/CPL DESs hydrates. As the hydrogen bonds of C–C═O–N···H···Br and C–C═O···H were broken, new bonds of C–C═O–N···H···SO and HO···H···SO formed and SO2 was absorbed in DES hydrates...

The caption:

Figure 12. 1H NMR spectra of TBAB/CPL before and after SO2 absorption (TBAB/CPL, molar ratio of 1:2, 2 mol L–1).

The caption:

Figure 13. Raman spectra of TBAB/CPL DESs and TBAB/CPL DES aqueous solutions before and after SO2 absorption (TBAB/CPL, molar ratio of 1:2, 2 mol L–1).

The caption:

Scheme 1. Proposed Mechanism between TBAB/CPL DES Hydrates and SO2

The caption:

Figure 14. Five continuous cycles of SO2 absorption (under atmospheric pressure, 20 °C) and desorption (N2, 50 °C) by TBAB/CPL DESs.

A caveat here concerns the stability of these reagents. To the extent that this reagents are exposed to acids, and one would imagine that a SO2 stream will necessarily be acidic, the stability of caprolactam to ring opening is certainly a major consideration.

Personally - and this is just a comment from the "peanut gallery" since I have not worked personally or directly with ionic liquids although I'm well acquainted with them - I think the ionic liquid routes are probably a better choice, since their toxicology can almost certainly be managed.

I don't necessarily like the way the solvents are regenerated, which seems to involve the use of a nitrogen stream, meaning the SO2 gas is impure and will need further processing.

Have a nice day tomorrow.

Flame Interactions of K, S Cl and CO in Oxygen Enriched Atmospheres.

The paper I'll discuss in this post is this one: Chemical Interactions between Potassium, Sulfur, Chlorine, and Carbon Monoxide in Air and Oxy-fuel Atmospheres (Thomas Allgurén and Klas Andersson, Energy & Fuels 2020, 34, 900−906).

Energy & Fuels, a publication of the American Chemical Society, an organization of which I am a long time member, is a journal I access every month, even though most issues are chock full of papers about a topic I absolutely deplore, dangerous fossil fuels. Of course, there are papers about dangerous fossil fuels that are well worth reading because the science therein may well prove to apply to things that actually are safe and sustainable. It is often the case that useful information can be obtained about energy and the environment by reading about systems that are either insidious or won't work, or are a little bit of both. For example I read papers all the time about making fuels using solar thermal plants, even though the small number of solar thermal plants that have actually been built end up being expensive, unreliable junk that damages or destroys pristine desert habitats. The reason is that the technologies that appear in solar thermal papers are adaptable to any source of high temperatures, even those that work. Many thermochemical cycles for splitting carbon dioxide, water or both, for example, make the requisite popularly driven genuflection to so called "renewable energy" but despite this appeal to unsustainable technologies, would work quite well with cleaner and far more sustainable nuclear energy.

This paper, cited at the outset, is not about technology that is directly applicable to nuclear energy, but it is very much about a product that is very useful for the removal of carbon dioxide from the air, pure oxygen, this being a side product of water or carbon dioxide splitting. The paper briefly mentions how this might work, specifically in the safe combustion of biomass (and or municipal garbage) in such a way as to make smoke stacks unnecessary. This type of combustion is called "oxy-fuel" combustion.

The combustion of biomass and/or municipal wastes is responsible for slightly less than half of the air pollution deaths which kill people continuously, at a rate of about 19,000 people per day while airheads run around complaining about so called "nuclear waste," which has a spectacular record of not killing anyone.

This is the world we live in. No wonder we now have a party - one dominated by a corrupt uneducated immoral moron - of people who used to wrap themselves in a flag threatening to nuke the planet to fight communism now bending all over itself to kiss the sphincter of a former KGB agent who now runs Russia.

And, it's not just them. We now have "environmentalists" who applaud the ripping up of wilderness for roads for trucks to drag wind turbine parts made from strip mined materials on diesel trucks.

Anyway, there is a difficulty with the combustion of biomass that anyone who has run a fireplace for a few decades will recognize. Biomass combustion effluents are not only toxic; they are corrosive.

I have been thinking and reading about this problem for quite some time: I'm jealous of my son studying materials science engineering and I'm always openly or surreptitiously working to pick his brain.

That's why this paper appealed to me.

From the introduction:

Today, it is generally accepted that the global temperature increase is largely a result of anthropogenic use of fossil fuels.(1) As a consequence, interest in alternative energy sources, such as biomass and waste-based fuels, has increased drastically in recent years. The global total primary energy supply has increased by an average annual rate of 1.9% since 1990, while at the same time, the primary energy supply from renewable sources has grown at a rate of 2.2%. In 2014, 13.8% of the global total primary energy supply was generated from renewable energy sources.(2) Despite this increase in renewable energy supply, there has been an increase in fossil CO2 emissions of almost 40% between 1990 and 2014. The largest share of global CO2emissions, 42%, is attributed to heat and power generation.(3) According to the International Energy Agency (IEA), in year 2014, more than 65% of the global electricity generation was based on the combustion of fossil fuels and more than 40% was from coal alone. Hydro represents the largest source of renewable electricity production (16%), whereas only 2% of the worldwide electricity generation is from the combustion of biofuels and waste. In addition, solar and wind, which are believed to play an important role in the future electricity production mix, are together with geothermal generation responsible for 4% of the total electricity production.(4) Thus, there is still a long way to go toward replacing the present use of fossil fuels.

A point: Reference 4, featuring the "4%" figure in "percent talk" - the talk that proponents of the wind and solar industry utilize to obscure its obvious failure of these hyped industries to address climate change - is not about total energy but rather about electricity. Specifically the reference is this: (4) International Energy Agency (IEA). Electricity Information 2016;
IEA: Paris, France, 2016; ISBN: 978-92-64-25865-5. After half a century of wild cheering, according to the 2019 edition of the World Energy Outlook, also published by the IEA but about primary energy, not electrical energy, as of 2018 all the world's solar, wind, tidal and geothermal sources on the planet produced 12.26 exajoules of energy out of 599.34 exajoules of energy consumed by humanity, in "percent talk," 2.04%.

The introduction continues:

An alternative path toward the replacement of fossil fuels is to lower the emissions of CO2 from the use of fossil fuels in stationary combustion facilities by adopting the concept of carbon capture and storage (CCS). CCS allows for the continued use of fossil fuels without emissions to the atmosphere of carbon dioxide; CCS is often referred to as a bridging technology that will allow for fast and drastic cuts in emissions, while more sustainable energy sources are being developed that can be adopted in a cost-effective and secure manner in the future.

An interesting possibility to reduce global warming is to combine the combustion of biofuels and CCS; this is commonly referred to as “bioenergy with carbon capture and storage” (BECCS). BECCS can help not only to reach a zero-emission target for power or industrial plants but also to achieve negative emissions locally. BECCS could be used to compensate for fossil CO2 emissions from sources for which a reduction might be more difficult to achieve. BECCS has also been proposed for the actual removal of CO2 from the atmosphere. Azar et al.(5) have shown that it is possible to reach the 2 °C target even if we, for a while, reach an atmospheric concentration of greenhouse gases otherwise considered too high, provided that BECCS is deployed.
With this background, this paper provides experimental and modeling work on the combustion chemistry relevant to fuel or fuel mixes with high concentrations of alkali, chlorine, and sulfur. The conditions are relevant for suspension-fired systems in both air–fuel and oxy-fuel combustion systems. In comparison to coal, biomass contains high levels of alkali metals and chlorine and low levels of sulfur. Given the fuel composition, significant amounts of alkali chlorides may be formed during the combustion of biomass, which increases the risk of high-temperature corrosion (HTC). However, during co-combustion of coal and biomass, fuel-bound sulfur in the coal may promote the sulfation rather than the chlorination of the alkali metals. The formation of HTC-related alkali species is investigated in the present work under both in-flame and post-flame conditions. The focus of this investigation is on the homogeneous gas-phase chemistry and includes both experimental work and detailed kinetic modeling

By the way, carbon capture and storage will not work and is not safe. However, carbon capture and use is very much worth considering. It is feasible, I think, to make materials now made through the agency of dangerous fossil fuel derived products from "Boudouard Carbon" - carbon made from the disproportionation of carbon monoxide, coal combustion in reverse, which obviously requires an energy input but is feasible with nuclear energy.

The interesting point raised in the paper is that the closed (smokestack free) combustion of biomass allows for concentrated and easy to separate carbon dioxide.

In biomass combustion in an oxygen environment - which involves high temperature - salts like potassium chloride and sodium chloride, which are always present in biomass are molten and hot enough to develop a significant vapor pressure and become gaseous and at high temperatures these salt gases are corrosive. Oxidized sulfur, from the combustion of the amino acids methionine and cysteine, as well as other thiolated molecules, generates sulfur dioxide and sulfur trioxide, the latter being the anhydride of sulfuric acid, and in the presence of steam, sulfuric acid itself.

The authors developed an apparatus to explore these gases present in flames. A schematic of the apparatus:

The caption:

Figure 1. Schematic of the 100 kW test unit at Chalmers University of Technology. The red arrows indicate the positions for the injection of KCl and SO2. The locations of the 15 measuring ports are indicated as M1–M15.

The behavior of KCl was monitored by spectroscopy using a system the authors dubbed IACM (in situ alkali chloride monitor) which is shown in the following schematic:

The caption:

Figure 2. Schematic of the IACM setup used in this work to measure the concentration of KCl over the cross section at M7: 1, UV light source; 2, aperture; 3, parabolic mirror; 4, ball valve with window inside; and 5, collimator connected to a spectrometer via an optical fiber.

Other gases in the system were analyzed by a piece of apparatus called an NGA 2000 which, as I understand it is a type of compact GC with an FID (Flame Ionization Detection) system. Since I am generally not familiar with this instrument, it probably behooves me to let the authors describe their analytical system. To wit:

. A NGA 2000 analyzer was used for measuring the levels of CO, CO2, O2, and SO2. This instrument uses the paramagnetic principle (O2), non-dispersive ultraviolet sensors (SO2), and non-dispersive infrared sensors (CO and CO2). A BINOS 100 analyzer was used to measure the levels of CO2 and O2 using infrared (IR) and electrochemical sensors. Two different Fourier transform infrared spectroscopy (FTIR) systems were used: MB9100 (Bomem, Inc., Québec City, Québec, Canada) and MultiGas 2030 (MKS Instrument, Inc., Andover, MA, U.S.A.). These systems generally measure warm (190 °C) and wet gases and can be used to detect a wide range of different compounds. In this work, they were, however, used to measure HCl. The temperature of the gas inside the furnace was measured using a suction pyrometer. The suction pyrometer is a water-cooled suction probe equipped with a thermocouple (type B).

The combustion here did not take place in a pure oxygen atmosphere. In fact the gas supporting combustion was carbon dioxide slightly enriched, with respect to air, in oxygen, to 25% and is thus designated OF25 in the paper.

Th oxygen/carbon dioxide system is a system about which I've been thinking "thought experiments" for quite some time, and I am pleased to see it discussed here. Note that if all of the oxygen in this system is consumed, the residual gas will be a mixture of CO and CO2, depending on the amount of unoxidized fuel in the system. If water is present, it will consist of small amounts of hydrogen gas and carbon dioxide, a very interesting system.

To return though, to the present case:

The reaction conditions are described in this table, Table 1, showing the amounts of KCl and SO2 injected into the system:

The overall conditions are shown in Table 2:

Here are the flames, pictured in the air and OF25 cases with and without KCl injections:

The caption:

Figure 3. Photos of the flame taken during operation. The air case both without and with KCl injection is shown in panels a and b, respectively, and both photos are taken in measurement port M2. The OF25 case is shown in panels c and d without and with KCl injection, respectively. The OF25 photos are from port M3.

What is being measured here is the interaction between sulfur, oxygen and potassium, in which case a significant portion of the gas is present as HCl gas, hydrochloric acid, which is obviously corrosive.

The effect of the potassium to sulfur ratio in the next graphic shows its effect on the resulting concentrations of HCl gas:

The caption:

Figure 4. (a) Measured and modeled HCl concentrations. (b) Measured and modeled available concentration of KCl. The KCl measurements were carried out using the IACM instrument.

The "degree of sulfation" refers to the amount of potassium being in the form of K2SO4. It is defined in this equation, equation 1 in the paper:

Graphically it is shown here under various reaction conditions:

The caption:

Figure 5. Degree of sulfation at the outlet of the isothermal PFR as a function of the temperature for four out of six investigated cases.

The following figures are probably best explained with some text from the paper:

Figure 6 shows the degree of sulfation as a function of time at a temperature of 1200 °C (Figure 6a) and 850 °C (Figure 6b) for the same four cases, as shown in Figure 5. The degree of sulfation is initially higher for those cases where CO is oxidized (N2–CO and CO2–CO). However, the influence of CO is even more evident in Figure 6b (850 °C), where the sulfation in the CO case is not only higher at the outlet compared to both the reference case at 850 °C and all cases at 1200 °C but also proceeds much faster. Note that, in the 850 °C case, there were no differences between nitrogen- and carbon-dioxide-based atmospheres; these data were therefore omitted.

The first 2 s of residence time in the 850 and 1200 °C cases in Figure 6 were used for a reaction path analysis, as presented in Figures 7 and 8. The thicknesses of the lines in these figures are proportional to the activity levels for that specific reaction or set of reactions. There are clearly higher sulfation activities in the N2–CO and CO2–CO cases (panels a and b of Figures 7 and 8, respectively) compared to the atmospheres that do not contain any carbon monoxide (panels c and d of Figures 7 and 8). The main activity is, however, not the formation of K2SO4 but the sulfation of KCl to KSO4 and KHSO4, of which the latter is thereafter desulfated back to KCl without reacting via the final step to form potassium sulfate. These reactions create a loop that acts as a net producer of sulfur trioxide. Therefore, in the N2–CO and CO2–CO cases, the SO3 concentrations are substantially higher for temperatures of <1000 °C compared to the cases in which no CO oxidation occurs, i.e., N2reference and CO2 reference.

Figure 6. Degree of sulfation in the PFR as a function of the residence time for the two different operating temperatures: (a) 1200 °C and (b) 850 °C.

The next two figures show all of the species identified in the flame as recorded over a period of a few seconds and the pathways between them, as described in the excerpted text above:

Figure 7:

The caption:

Figure 7. Reaction path analysis of the first 2 s in the PFR, representing the results presented in Figure 6b.

"PFR" designates the reactor, a "Plugged Flow Reactor."

Figure 8:

The caption:

Figure 8. Reaction path analysis of the first 2 s in the PFR, representing the results presented in Figure 6a.

The disproportionation of KO- species into potassium metal is interesting; I have considered this reaction for the two higher alkali metals, rubidium and cesium for certain applications. When I was a kid this reaction would have surprised me, but now older, I am aware of it. In this setting potassium metal is only meta stable, and won't survive very long, as the pathways clearly indicate. Nevertheless at 1200°C, its formation is a major reaction.

The thermal decomposition of oxygen containing species is always of interest, although clearly in this system, the recombination is very fast, the free metal is a transitory intermediate.

The next graphic is also relevant to thermochemical water splitting, because the equilibrium it shows between SO3/H2SO4 and SO2 gas is a component of the famous and widely explored sulfur-iodine cycle, which I'm sure I've discussed somewhere on the internet, if not here. This is not my favorite thermochemical cycle, but it's growing on me, owing to certain insights as to how it may become a continuous process. Continuous processes, while they can be challenging, when fully developed are always or at least always more economically viable than batch processes. (Which is yet another reason why solar thermal schemes are doomed to economic failure.)

The caption:

Figure 9. Ratio of SO3/SO2 at the oulet of the PFR for different temperatures in the reactor. The included experimental data are taken from Fleig et al.(17)

A graphic relating to the presence of free radicals, which are nice things when one is getting potential pollutants to decompose.

The caption:

Figure 10. Concentrations of (a) H and (b) OH radicals when the PFR temperature was set at 1200 °C. Note that the CO and reference cases are presented on separate y axes in panel a.

Finally, the effect of distance from the burner on CO concentrations with injections of SO2 and KCl:

The caption:

Figure 11. CO concentrations for (a) five air cases and (b) six OF25 cases with and without injection of KCl, SO2, and water. The cases are defined as follows: ref, reference case (no injection); W, injection of pure water; K, injection of KCl; S, injection of SO2; KS, injection of both KCl and SO2; and 2K, double amount of KCl injected.

Although I'm generally dismissive of so called "renewable energy," biomass represents a special case, since there are areas where there is biomass as a pollutant, i.e. lakes and seas suffering from eutrophic oxygen depletion, and because biomass may represent the lowest cost path to removing the dangerous fossil fuel waste from the atmosphere.

From the paper's conclusion:

The use of biomass and waste as fuels for combustion processes is expected to increase during the coming years because this represents a possibility to reduce fossil CO2 emissions. The relatively high content of alkali metals and chlorine found in biomass compared to coal increases the risk for problems related to deposition and high-temperature corrosion. The related chemistry is therefore important to use the biomass in the best way possible, i.e., to maximize the thermal efficiency in power plants. This work focuses on the K–Cl–S chemistry relevant for combustion in flames. The work includes experiments performed in a 100 kW combustion test unit together with kinetic modeling performed using Chemkin.

In this work, detailed kinetic modeling was performed to examine the influence on potassium chloride sulfation of CO oxidation in combination with the replacement of nitrogen with carbon dioxide. The oxidation of CO enhances the kinetics of alkali sulfation, in particular, at temperatures of <1000 °C. At higher temperatures, sulfation is promoted even further if the concentration of CO2 is also high. The experimental data presented in this work show that favorable conditions for alkali sulfation are naturally mediated by flue gas recirculation in oxy-combustion, leading to elevated SO2, CO2, and CO concentrations...

This is an esoteric but important paper, to my thinking, on engineering the removal of the dangerous fossil fuel waste carbon dioxide from the atmosphere, something future generations - all who come after us - will need to do, simply because we were rotten forebears and didn't care a whit for them.

History will not forgive us, nor should it.

Have a nice evening.

Total Synthesis of a Stereochemically Pure "Topoisomer."

The paper I'll discuss in this post is this one: Total synthesis reveals atypical atropisomerism in a small-molecule natural product, tryptorubin A (Solomon H. Reisberg1, Yang Gao1, Allison S. Walker2, Eric J. N. Helfrich2, Jon Clardy2,*, Phil S. Baran1, Science, Vol. 367, Issue 6476, pp. 458-463.

One may say "Life is unfair," because there is asymmetry in the way people are treated, an orange lunatic might with no personal merits, low intelligence and no integrity whatsoever might end up living in the White House, supported by a criminal rabble, while a person like Raoul Wallenberg might die alone, possibly under horrific conditions, in a Soviet Prison.

But life is asymmetric both in a moral sense and also in a physical sense.

This is the science section of a website devoted mostly to the issue of political ethics, and so here, we limit discussion to physical realities.

The physical asymmetry of life involves chirality, the property of objects that are not superimposable on their mirror images, the most common evocation of which are the human hand because the left hand is (more or less) the mirror image of the right, but the two hands cannot be superimposed upon each other. In fact, a word often used, even by scientists, to describe chirality is "handedness."

Most of the organic molecules in living systems possess this property of chirality, with some exceptions, for example the common amino acid glycine, and the acid pyruvic acid, but the other 19 coded proteogenic amino acids, all sugars, and all of the nucleic acids possess chirality.

In almost every case, the chirality is associated with one or more "chiral centers" where the chirality derives from the tetrahedral arrangement of bonds to saturated carbon, if these bonds are attached to four different types of groups, the molecule is chiral. Some amino acids, threonine and isoleucine have two chiral centers, and others, like sugars (which also cause the asymmetry of nucleic acids of which they are a constituent) can have many chiral centers.

However there is a somewhat unusual type of chirality that can be present without a chiral center that derives from rigid bonds to carbons that are lacking in chiral centers. Most organic chemists will be familiar with well known chiral catalysts - in order to synthetically generate a chiral center, one must introduce a chiral molecule into the synthetic pathway somewhere - based on "Binap" which has this property:

Although the molecule here is a peptide, and possesses amino acids having chiral centers, including isoleucine having two chiral centers, it also possesses the other kind of chirality. The molecule is tryptorubin A, a cyclic peptide, with non-amino acid moieties in it (that clearly can be distinguished as having been biosynthesized from amino acids. Tryptorubin A was discovered in the bacteria associated with the fungus that is in a symbiotic relationship with a species of ants.

Similar molecules, modified cyclic peptides, have proven to be important medications; vancomycin, an antibiotic that is a "antibiotic of last resort" for treating bacterial infections caused by organisms that have evolved resistance to many other antibiotics, is in this class.

Anyway, the authors of this paper have discovered interesting stereochemical properties of this molecule, tryptorubin A as a result of working on its total synthesis.

The introduction to the paper is well written, and should be accessible to some non-chemists:

In 1894, Emil Fischer proposed a lock-and-key analogy for how biological molecules interact to carry out biological functions, and the three-dimensional (3D) shapes of molecules have been a major focus of biological chemistry ever since (1). Accordingly, the structure of small molecules has been assumed to be defined solely by atomic connectivity and point or axial chirality. For example, the steroid hormones all have the same basic carbon skeleton—a rigid assembly of four rings fused one to another—and their different biological roles depend on the modifications to the periphery of this basic skeleton. In contrast, large molecules such as proteins can reversibly self-organize into well-defined 3D structures, and the rules governing this ability are increasingly well understood (2). This structural feature of biological macromolecules encodes many of the functions that form the basis of life (1). For example, hydrogen-bonding, hydrophobic, arene-π, and solvation interactions drive proteins to fold into specific tertiary structures that render them operable (2). Molecular shapes (i.e., tertiary structures) for most macromolecules are derived from atomic connectivity but are fundamentally separate from it; that is, many proteins can be folded and unfolded without breaking or forming covalent bonds (3).

For certain macromolecules, however, shape is directly tied to atomic connectivity rather than to conformational changes (Fig. 1A, left). In the case of cyclic DNA, for example, the wound and unwound topologies are interconvertible only by the scission and reformation of phosphate linkages (4). Likewise, molecular catenanes have been synthesized with defined topology (5). Such nonsuperimposable and noninterconvertible topologies are called topoisomers. Two molecules are topoisomers of each other if they have identical connectivity but nonidentical molecular graphs—that is, molecular pairs that are noninterconvertible without the breaking and reformation of chemical bonds (6).

The next parts may be less accessible to non specialists:

This type of defined topoisomerism is conspicuously absent from small-molecule natural products. A distinct, if seemingly analogous, isomerism in a small-molecule context is atropisomerism (i.e., shape isomerism through hindered bond rotation). Canonically, atropisomerism involves a single torsionally hindered bond that bestows axial chirality; hindered biaryls (Fig. 1A, right) represent a prototypical example.

In contrast to both canonical (singly axially chiral) atropisomerism and topoisomerism, there exist a variety of shape-defined molecules that are theoretically interconvertible by bond rotation but are categorically distinct from canonical atropisomers because of the multiple and nonphysical bond torsions required for their interconversion. Many mechanically interlocked molecules fit into this middle ground; for example, both rotaxanes (7) and lasso peptides (8) (Fig. 1A, center) are topologically trivial and should formally be considered atropisomers with their unthreaded counterparts, but are clearly categorically distinct from simple prototypical examples of atropisomerism. [For another compelling case of noncanonical atropisomerism, see (9).] In a physical (rather than theoretical) sense, most members of the lasso peptide class of natural products can be interconverted from unthreaded to threaded shapes only by breakage and repair of the peptide backbone...

Figure 1:

It's caption:

Fig. 1 Shape isomerism in macro- and small molecules.
(A) Shape-based isomerism in synthetic and natural products spans a broad range. At one end (left), defined topology encodes topoisomers. At the other end (right), canonical atropisomerism is defined by simple axial differences (i.e., torsion of a single bond). Under the broad umbrella of atropisomerism, but distinct from more canonical examples, are noncanonical atropisomers (center) that are formally topologically trivial, but whose interconversion requires complex multibond rotations and unphysical torsions. Historically, this area has been occupied only by macromolecules; in this work, we disclose a small-molecule natural product that presents this type of noncanonical atropisomerism. Structures obtained from PDB and/or CCDC database: circular DNA, reproduced from (30); lasso peptide, PDB 5TJ1 (8); catenane, CCDC #1835146 (5); rotaxane, CCDC #1576710 (7). (B) Left: Originally proposed structure of tryptorubin A. Right: Two noncanonical atropisomers are possible within the limits of the originally proposed 2D structure. Note that 3D structures of 1a and 1b are computed, not crystallographic, and their terminal residues are truncated for clarity.

The point of the paper is described here:

...We have found that tryptorubin A (1), as a result of chirality and connectivity alone, could theoretically present as two possible noncanonical atropisomers. We describe an atroposelective synthesis of atrop-tryptorubin A (1b), the discovery of its atypical atropisomerism, and a hypothesis-driven atropospecific strategy that led to the synthesis of the natural product (1a) and its unambiguous atropisomeric assignment. Additionally, we report genomic data that help to clarify the biogenesis of 1a; these data suggest a biosynthetic pathway involving ribosomal peptide synthesis followed by atroposelective posttranslational modification...

The authors began their synthesis with the protected version of a the dipeptide Tryptophan-3-iodotyrosine methyl ester and went through a number of (fairly low yielding) steps:

The caption:

ig. 2 Tryptorubin A’s noncanonical atropisomerism: Discovery and synthesis of the unnatural atropisomer.
(A) Synthetic route to atrop-tryptorubin A (1b). (B) Strategic hypothesis to use point chirality to drive an atropospecific synthesis of tryptorubin A. Piv, pivalate; PMB, para-methoxybenzyl; Ns, nosyl; DTBMP, 2,6-di-tert-butyl-4-methylpyridine; HATU, hexafluorophosphate azabenzotriazole tetramethyl uronium; PyAOP, (7-azabenzotriazol-1-yloxy)tripyrrolidino-phosphonium hexafluorophosphate; nOe, nuclear Overhauser effect.

This represented, I'm sure, a huge amount of work for graduate students and/or postdocs.

And then they discovered that this was a case, as someone - I forget who - said of the origin of advances in basic science, where the scientists said, "Hey, that's funny..."

This is a somewhat esoteric description of "Hey, that's funny..." but trust me, that's what it is:

At this juncture, characterization by nuclear magnetic resonance (NMR) spectroscopy became challenging (even at high temperature), presumably because of cis/trans amide isomerization of the tertiary pyrroloindolinyl amide, various rotameric populations, and conformational equilibrium between 8a and 8b. Nonetheless, 8 appeared as a single sharp peak in high-performance liquid chromatography (HPLC) and exhibited a high-resolution mass spectrum (HRMS) consistent with the postulated structure. After extensive experimentation (13), this structure could be cyclized in low yield to a bis(macrocycle). Global deprotection yielded 1b, with HRMS data indicating the same molecular formula as the natural isolate (1). Unfortunately, the NMR data [1H, 13C, heteronuclear multiple bond correlation (HMBC), heteronuclear single quantum coherence (HSQC), rotating-frame nuclear Overhauser effect correlation spectroscopy (ROESY)] and LC retention of 1b were distinct from the natural product (1) [see below and (13)].

With these contrasts in spectral data in mind, we began to consider possible explanations for the structural discrepancy between 1 and 1b. We considered the possibilities of stereochemical misassignment (e.g., a D–amino acid) or regiochemical misassignment (e.g., alternate regiochemistry in the indole-pyrroloindoline C-C bond) in the natural and/or synthetic products. After exhaustive review of natural 1 and synthetic 1b’s respective spectral data as well as a separate total synthesis of C26-epimeric species epi-8 [see (13) for this additional synthesis], we confirmed that natural 1 and synthetic 1b had the same connectivity and point-stereochemistry (13). It was only upon careful analysis of the two compounds’ ROESY spectra that a key insight was discovered: Although the natural product (1a) showed strong nuclear Overhauser effect correlations from H9 and H10 to H42 (Fig. 2B), the analogous H9 and H10 protons in the synthetic (1b) compound’s ROESY spectrum showed correlations to H40 (Fig. 2A). This key geometric constraint, combined with additional spectral evidence [1b and 1a in Fig. 2, A and B; see (13) for additional details and full skeletal numbering system], illuminated our understanding that even within the limits of identical connectivity and stereochemistry, 1 could potentially exist as two noncanonical atropisomers (“bridge above,” 1a; “bridge below,” 1b)...

... We hypothesized that by geometrically locking the cyclization precursor into the “bridge above” conformation, we could achieve inversion of atroposelectivity. Combining this hypothesis with crystallographic evidence of the geometry of indoline 7, we recognized that in a substrate such as indoline 9, the point chirality at indoline (Fig. 2B, purple methine) would geometrically preclude the “bridge below” conformer (9b); indeed, geometric limitations of 9 would render the cyclization atropospecific for the “bridge above” atropisomer 1a (resulting from cyclization of 9a). Such a strategy is reminiscent of methods to control more canonical atroposelectivity by point-to-axial chirality transfer (18).

Figure 3A describes our successful execution of the atropospecific strategy laid out in Fig. 2B and the subsequent total synthesis of the natural isomer of tryptorubin A (1a)...

Figure 3:

It's caption:

Fig. 3 Total synthesis of tryptorubin A.
(A) Atropospecific synthesis of tryptorubin A (1a). (B) Top: A RiPP sequence that encodes tryptorubin A’s linear peptide sequence. Bottom: Proposed biosynthetic pathway to 1a. Amino acid abbreviations: A, Ala; F, Phe; H, His; I, Ile; K, Lys; L, Leu; M, Met; N, Asn; Q, Gln; R, Arg; S, Ser; W, Trp; Y, Tyr.

A graphical cartoon ("thought experiment" ) from the paper:

Fig. 4 Graphical thought experiment considering putative interconversion of tryptorubin (1a) and its noncanonical atropisomer (1b).

Top: Theoretically, interconversion would require an unphysical inside-out flipping of the molecule, in which one macrocycle passed through the other. Center: This is analogous to atropisomeric inversion of a rotaxane, which would require unphysical stretching of the ring (green) over the dumbbell. Bottom: Such noncanonical atropisomers are contrasted with prototypical atropisomers such as binaphthol, which can interconvert through simple bond torsion.

Some commentary of the synthetic biology of this interesting molecule:

The discovery of tryptorubin A’s geometric isomerism in the total synthesis effort prompted a reexamination of its biosynthesis. The original bioinformatic analysis identified 18 biosynthetic gene clusters (BGCs), none of which could be confidently predicted to encode the biosynthesis of tryptorubin A (12). The most plausible candidate was a modular nonribosomal peptide synthetase by which the hexapeptide chain would be assembled sequentially by dedicated enzymes. However, the selectivity of the module-encoded adenylation domains did not convincingly match the tryptorubin A peptide sequence, and additional genes involved in the biosynthesis of amino acids that are not incorporated into tryptorubin A were present in the direct vicinity (22, 23). We decided to evaluate other possible biosynthetic origins and thus considered the possibility that tryptorubin A is a ribosomally synthesized and posttranslationally modified peptide (RiPP) that is missed by conventional bioinformatic analysis tools because of its small size, its lack of homology to characterized ribosomal peptides, and the presence of noncanonical tailoring genes involved in carbon-carbon bond formation...

...Screening the translated Streptomyces sp. CLI2509 genome sequence for the tryptorubin core peptide sequence (Ala-Trp-Tyr-Ile-Trp-Tyr) resulted in a single hit. Close inspection of the unannotated region revealed a ribosomal binding site followed by a transcriptional start site, a putative RiPP precursor gene encoding a 20–amino acid leader, a core peptide, and a stop codon downstream of the core sequence (Fig. 3B and fig. S17). This sequence is followed by a gene encoding a cytochrome P450 enzyme that is likely involved in the formation of the nonproteogenic carbon-carbon and carbon-nitrogen bridges. Although cytochrome P450 enzymes that catalyze carbon-carbon bond formation in ribosomal peptides have not been reported (24), analogous carbon-carbon linkages between the aromatic residues in the nonribosomal peptide vancomycin have been shown to be installed by cytochrome P450 enzymes (25–28)

Thus spake Vancomycin.

A concluding remark:

Despite the extensive vernacular to describe regio-, stereo-, and atropisomers, the nuances of molecular shape can be lost within the realm of small-molecule natural product chemistry. Although most practicing synthetic chemists are intimately familiar with the canonical examples of biaryl atropisomerism, the much more complex examples of atropisomerism in polycyclic and mechanically interlocked molecules often remain underexamined. Indeed, the possibility of noncanonical atropisomerism was initially missed during both the isolation and synthesis of tryptorubin A. We present this case as a cautionary tale in structural definition, a demonstration of the power of transferring point chirality to molecular shape, and a reminder that small-molecule organic chemists can greatly benefit from the deep understanding of 3D structure known in the biomacromolecular and supramolecular literature.

I don't know what the "use" of this science might be, but irrespective of its use, it is beautiful, and its wonderful to contemplate a beautiful thing on a Sunday afternoon.

I hope your Sunday afternoon is as wonderful as mine. First life is wonderful, and then you die.

We briefly set an all time new record for CO2 concentrations at Mauna Loa in January(!!) 415.79 ppm.

Because we are supremely uninterested in doing anything serious at all about climate change beyond offering silly platitudes about what so called "renewable energy" will do "by [insert some year 20 or 30 years off here]," a new all time record for carbon dioxide concentrations measured is set every year.

As I often note in this space the readings are sinusoidal, superimposed on a steadily rising slightly less than linear axis, as this graphic, which I often reproduce, from the Mauna Loa website shows:

Every year, like clockwork, a new all time record is set in May.

I check the Mauna Loa website weekly on Sundays to update my spreadsheet for weekly year-to-year increases, and this morning the data isn't up yet, so I went over to the daily readings, and to my surprise, found this:

Recent Daily Average Mauna Loa CO2 (Accessed 1/26/2020, 6:29 am)

January 24: Unavailable
January 23: Unavailable
January 22: 414.08 ppm
January 21: 415.79 ppm
January 20: 413.25 ppm
Last Updated: January 25, 2020

For weekly data, the all time records at Mauna Loa are these for the last few years:

For 2015, set in the week of May 3, 404.11 ppm
For 2016, set in the week of May 22, 408.31 ppm
For 2017, set in the week of May 14, 410.36 ppm
For 2018, set in the week of May 13, 411.85 ppm
For 2019, set in the week of May 12, 415.39 ppm

I don't record the daily data, and there may have been higher daily spikes in the past; I don't know.

Nevertheless, to the best of my recollection, I have never seen any data point as high as 415.79 which I put bold above, as recorded on January 21 of 2020.

It may be related to the Australian fires, and may represent to some extent statistical noise, but, still, this is very, very, very scary, unbelievably scary, particularly to see it in January.

If any of this troubles you, don't worry, be happy. Head over to the E&E forum to read all about some pristine wilderness being torn apart to make roads for trucks delivering huge steel towers for the latest wind farm, which will be illiterately discussed with the fraudulent unit "megawatts." This destruction of pristine wilderness areas has nothing to do with the environment, and nothing to do with climate change, but it's very popular stuff in modern advertising and makes everyone feel all warm and fuzzy, except, perhaps, me.

Have a pleasant Sunday.
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