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My books says how carbon monoxide will react with hydrogen to give different products with different catalysts, but how exactly do different catalysts yield different products. Do they provide different pathways for entirely different mechanisms, or is the formation of some products is better thermodynamically and for that reaction to occur some catalysts provide the necessary activation energy and the others cant. enter image description here

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  • $\begingroup$ All true what you say, it all depends on the temperature, (partial) pressures, activation energies, mechanistic pathways, catalyst morphology, ... $\endgroup$ – Karl Aug 24 at 14:38
  • $\begingroup$ So its difficult to pinpoint what exactly is different specifically? $\endgroup$ – SOSXX Aug 24 at 15:56
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The thermodynamics are always the same. If you go from carbon monoxide to methane, there is only one final enthalpy, and if you have the choice of going to methane or methanol the thermodynamically preferred product is always the same.

The difference indeed less within the different pathways and the activation barriers needed to get from one intermediate to the next. This isn’t really thermodynamics, it is mainly kinetics (although you can argue about thermodynamically preferred intermediates). The pathways are often very complex and entire papers revolve around how one reaction is catalysed on such a solid state catalyst, so please forgive me for not looking them up; but the general point still stands: one catalyst will lead to intermediates where the $\ce{C-O}$ bond is easily broken (and thus give methane), the other will not (and thus give methanol).

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  • $\begingroup$ Wow, two answers in a raw. It's great to see you back, Jan:) $\endgroup$ – andselisk Aug 24 at 19:03
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    $\begingroup$ @andselisk Only briefly visiting on my tablet ;) $\endgroup$ – Jan Aug 24 at 19:04

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