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I am trying to build a machine that converts carbon dioxide and water into gasoline (i.e. octane). Because the energy needs are so large, is there any catalyst chemical that can cause "reverse combustion" at room temperature?

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    $\begingroup$ Catalyst or no catalyst, the energy needs are still as large as they were. $\endgroup$ Jan 23, 2020 at 20:12
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    $\begingroup$ If we had that catalyst, we won't have greenhouse effect any more. Yet, there were some publications on turning $\ce{CO2}$ into methanol (not exactly hydrocarbon and oxygen). You can find these info here. As we all know and as sighted in this paper, Turning $\ce{CO2}$ into fuels is exactly what photosynthetic organisms have been doing for billions of years, although their fuels tend to be foods, like sugars (here, your catalyst is chlorophyll). $\endgroup$ Jan 23, 2020 at 23:00
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    $\begingroup$ As above, this is somehow a field. Point is that the energy must be of "green" type. But even running your own PV panel thermodynamics is indeed challenging. I would say proibitive, but I am not a particularly optimistic and "visionary" person so let's hope one day.... $\endgroup$
    – Alchimista
    Jan 24, 2020 at 7:56

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By principle, all catalysts accelerate both forward and backward reactions in the same extent, so the equilibrium with and without the catalyst is the same.

So the catalyst catalysing the "reversed combustion" would catalyze the normal combustion as well. The equilibrium would be far at the combustion products side, as if the catalyst was not used.

If it had not been so, one could have constructed a chemical perpetuum mobile. It could generate energy by shifting equilibrium forward and backward just by adding and removing the catalyst.

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  • $\begingroup$ but is there a catalyst or not? $\endgroup$
    – WarpPrime
    Jan 23, 2020 at 21:58
  • $\begingroup$ As platinum is a catalyst of combustion, it is a catalyst of reverse combustion as well. It helps you reach the equilibrium, which is fully on the side of H2O and CO2. :-) Without provided energy, like attempts to use first steps of photosynthesis, catalysts are useless. $\endgroup$
    – Poutnik
    Jan 24, 2020 at 1:37
  • $\begingroup$ thanks! but is there anything cheaper? $\endgroup$
    – WarpPrime
    Jan 24, 2020 at 13:39
  • $\begingroup$ Yes, there is plant photosynthesis. If there was a cheap, easy and revolutionary solution, it would be already in place. $\endgroup$
    – Poutnik
    Jan 24, 2020 at 17:20

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