Comment by Barrera | Hacker News Reader

Comment by Barrera | Hacker News Reader

I'm wondering if the last sentence from the abstract is more of a holy grail than the conversion of methane to methanol:

> ... The confinement of mono-iron hydroxyl sites in a porous matrix demonstrates a strategy for C–H bond activation in CH4 to drive the direct photosynthesis of CH3OH.

https://www.nature.com/articles/s41563-022-01279-1

Selective C-H bond activation (of which this paper is an example) is extremely difficult. It has been the focus of intense research for decades. Having a tunable catalysts system that performed this transformation would be a game-changer for the production of just of about every organic molecule. The authors just focused on methane as the hydrocarbon feedstock, so it's hard to know how general the process might be.

That doesn't sound very selective to me, considering that the CH bonds on methane are all theoretically equivalent. Could you expand on this idea?

Selective here means it adds a single OH (alcohol group) to methane and not two, there, four.

If you keep adding alcohols (otherwise known as oxidation), you would end up with CO2 and waters - the same as burning methane.

There is a massive property boon going from methane (gas) to methanol (liquid and easy to transport) and not further

Is adding an OH to CH4 energetically equivalent for each successive OH added? Or at least close enough for the difference not to matter?

The first oxidation step, from an alkane, like methane, to an alcohol, like methanol, is always the most difficult, i.e. the least likely to happen spontaneously.

The next oxidation steps, from an alcohol to an aldehyde (formaldehyde in this case), then to a carboxylic acid (formic acid in this case), then to carbon dioxide, are much easier to initiate.

So doing the oxidation only up to methanol, without losses into more oxidized compounds, is not likely to happen in the absence of a very selective catalyst, like in this case.

This makes sense, thank you for the in-depth answer!

No

I mean, if the claims hold up and _only_ work for this particular interaction, it will still be workd-changing. Methanol production underpins an embarrassingly large chunk of the modern world.

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