General Discussion
Related: Editorials & Other Articles, Issue Forums, Alliance Forums, Region ForumsCould on-vehicle CO2 catalysis cut down on global warming?
This is done over one of several catalysts:
2CO2 -> 2CO + O2
Or in English, carbon dioxide dissociates into carbon monoxide and oxygen. Chemical plants that make things from carbon monoxide (a LOT of things are made from it) run the smoke from their heat sources across catalysts, recover the CO and use it in their processes.
Now, here's my idea: since carbon monoxide is a fuel gas, why couldn't they put a catalyzer in the exhaust system of a car and feed the carbon monoxide into the intake manifold?
jeff47
(26,549 posts)You have to add more energy in order to get the carbon monoxide. You can't get it "for free". You're better off not burning more fuel to produce CO which you then inefficiently burn in the engine.
jmowreader
(53,277 posts)jeff47
(26,549 posts)Catalysts reduce the amount of energy required to trigger a chemical reaction.
Normally, you have to add a lot of energy to cause the atoms to re-arrange themselves, and then you end up with compounds that contain less energy than it took to trigger the reaction. It's commonly called "activation energy".
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Your chemicals start with energy at X, and end up at energy Y. To get from X to Y, you have to go over that big hump to "break" your initial chemicals apart, so they can be rearranged into the new chemicals.
Catalysts lower how tall that hump is, as shown by the red line. But there is still a hump.
As for feeding the CO back into the engine, no process is 100% efficient. "Burning" the CO produces less energy than it took to make the CO. And energy includes heat. So your CO-burning engine would need to burn more fuel to produce the CO to burn. You're better off just releasing the CO2.
It should be noted that catalytic converters do work from the heat of exhaust gasses, but the reactions in the catalytic converter are running "downhill" energy-wise. In the graph above, the catalytic converter is going from Y to X. That means you don't need nearly as much energy, and exhaust gas heat is sufficient. The catalytic converter is going from CO to CO2, instead of your proposed CO2 to CO.
jmowreader
(53,277 posts)We know CO2 is a greenhouse gas.
We know burning petroleum produces CO2.
We know CO2 can be sent through a hot catalyst to split it into CO and O2.
We also know CO isn't a very efficient fuel - the low-grade producer gas this would make throws off less than 200 btu per cubic foot at atmospheric pressure.
Given ALL THAT, if we were to approach this strictly on a CO2-reduction basis, would installing a CO2 catalytic converter in a car, and piping the CO it creates into your intake manifold, reduce the amount of carbon dioxide the car makes by a noticeable amount?
jeff47
(26,549 posts)Because CO2 (and water) is the end result of fuel consumption. Including burning CO.
No. It would increase the amount of CO2 the car makes.
Something has to supply the energy to convert CO2 into CO. And heat of exhaust isn't enough energy. On top of that, you can not recover all of this energy by burning the CO.
The only energy source available is gasoline. So to get the extra energy to make the CO, you have to burn more gas, releasing more CO2 than if you did nothing.
You are attempting to propose a perpetual motion machine.
lumberjack_jeff
(33,224 posts)Assuming you could catalyze CO2 and capture the CO, then burn it...
... doesn't CO oxidize as CO2?
In fact, Catalytic converters work by combining unburned HC + CO (smog) + O2 ----> CO2 + H2O
jmowreader
(53,277 posts)And then THAT CO2 would be processed back into CO and the party would continue unabated.
lumberjack_jeff
(33,224 posts)Edim
(312 posts)It wouldn't reduce any CO2, because burning CO results in CO2 again. Furthermore, you need energy to reduce CO2 to CO. Also, you wouldn't need a catalyzer - just incomplete combustion. It would be senseless.
KamaAina
(78,249 posts)jmowreader
(53,277 posts)One_Life_To_Give
(6,036 posts)Sorry but it takes more energy input to get CO2 to convert to 2CO + O2 than you can recover when burning CO + O2 to give CO2.