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jmowreader

(53,277 posts)
Mon Dec 7, 2015, 04:07 PM Dec 2015

Could 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?

12 replies = new reply since forum marked as read
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Could on-vehicle CO2 catalysis cut down on global warming? (Original Post) jmowreader Dec 2015 OP
Because of thermodynamics. jeff47 Dec 2015 #1
So exhaust heat wouldn't be enough to activate a catalyst? jmowreader Dec 2015 #2
Catalysts aren't things that get "activated". jeff47 Dec 2015 #5
I'm not thinking about cutting fuel consumption here jmowreader Dec 2015 #7
If you aren't cutting fuel consumption, you're producing more CO2. jeff47 Dec 2015 #10
I apparently am missing the point. lumberjack_jeff Dec 2015 #3
Of course it does jmowreader Dec 2015 #9
*slow blink* n/t lumberjack_jeff Dec 2015 #11
In case you're not joking, Edim Dec 2015 #4
I'd be rather concerned abot CO leaks into the vehicle KamaAina Dec 2015 #6
I thought about that...putting the reactor in the engine compartment would help jmowreader Dec 2015 #8
Perpetual Motion? One_Life_To_Give Dec 2015 #12

jeff47

(26,549 posts)
1. Because of thermodynamics.
Mon Dec 7, 2015, 04:56 PM
Dec 2015

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.

jeff47

(26,549 posts)
5. Catalysts aren't things that get "activated".
Mon Dec 7, 2015, 05:08 PM
Dec 2015

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".



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)
7. I'm not thinking about cutting fuel consumption here
Mon Dec 7, 2015, 05:35 PM
Dec 2015

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)
10. If you aren't cutting fuel consumption, you're producing more CO2.
Mon Dec 7, 2015, 05:40 PM
Dec 2015

Because CO2 (and water) is the end result of fuel consumption. Including burning CO.

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?

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)
3. I apparently am missing the point.
Mon Dec 7, 2015, 05:03 PM
Dec 2015

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)
9. Of course it does
Mon Dec 7, 2015, 05:38 PM
Dec 2015

And then THAT CO2 would be processed back into CO and the party would continue unabated.

Edim

(312 posts)
4. In case you're not joking,
Mon Dec 7, 2015, 05:07 PM
Dec 2015

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.

One_Life_To_Give

(6,036 posts)
12. Perpetual Motion?
Mon Dec 7, 2015, 06:35 PM
Dec 2015

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.

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