Could on-vehicle CO2 catalysis cut down on global warming?

[jeff47]

5. Catalysts aren't things that get "activated".

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.