It’s...interesting work, I guess? I’d like to see a replication of that, actually, since their reported Faradaic efficiency from N2 is much higher than previous papers.
If you’re asking about whether it’s economically competitive with the Haber process (which IMO should be named after Le Chatelier instead) the answer is definitely not.
Electrochemical processes are usually more expensive than non-electrical ones, because you need to have electric current across a large surface area, which is harder than catalyst with large surface area. Consider the cost per mol of NaOH, the main thing made by electrolysis now, and then consider that the linked paper is using fancier stuff than salt water / nafion / etc. While the thermodynamically required voltage is lower, this is a harder reaction than water electrolysis because N2 is hard to react, and I’d expect it to be more expensive than hydrogen from water.
Even if the cells were free, I don’t think their electrolyte is stable for long enough to make that competitive.
Ammonia is cheap to make. If you look at historical prices you can see it can be made for $300/ton with current methods; there have just been price spikes due to supply/demand issues.
Thank you for the answer! One of the things I was curious about was indeed economic competitiveness, so it’s good to know that it won’t be any time soon.
All knowledge is worth having. But in particular, I’m interested in possible replacements for the Haber-Bosch-LeChatelier process. Yes ammonia is cheap, but we also use a heck of a lot of it. Can you imagine any new process ever bringing down the price further?
Also, from the electro-chemistry side, for this particular paper, what actually does the breaking of the triple bond? Electrolysis of water makes sense to me because I know that water molecules fall apart and come back together all the time in liquid water. So if I think about electrolysis as just kind of nudging the ions to each side of the container and then donating/stealing electrons to/from them once they reach the electrodes, it makes sense to me (this may be oversimplified/wrong). Diatomic nitrogen doesn’t spontaneously fall apart as far as I know? For electrochemical processes in general, is there a large voltage drop at the surfaces of the electrodes?
No need to respond to all or any of these. But you did ask. :)
water molecules fall apart and come back together all the time in liquid water
Water molecules can dissociate into [H3O+] and [OH-] - sort of, they’re complexes with more water with partially-covalent hydrogen bonding. But you can’t just go directly from those to H2 and O2 - for good efficiency you need fancy catalysts and it’s a multistep process starting with OH or H bonding to a metal surface.
Nitrogen conversion generally starts with the end or side of N2 bonding to a metal ion. (Usually the end, IIRC.) The triple bond has electron density far enough away from the nuclei for that to happen. It’s more diffuse and bigger electron density than the orbital of N in NH3 that can get protonated, so it interacts better with positive metal ions bigger than H but smaller than molecules.
Thoughts on this paper about an improved electrochemical process to fix nitrogen? (Originally came across this in a youtube video.)
It’s...interesting work, I guess? I’d like to see a replication of that, actually, since their reported Faradaic efficiency from N2 is much higher than previous papers.
If you’re asking about whether it’s economically competitive with the Haber process (which IMO should be named after Le Chatelier instead) the answer is definitely not.
Electrochemical processes are usually more expensive than non-electrical ones, because you need to have electric current across a large surface area, which is harder than catalyst with large surface area. Consider the cost per mol of NaOH, the main thing made by electrolysis now, and then consider that the linked paper is using fancier stuff than salt water / nafion / etc. While the thermodynamically required voltage is lower, this is a harder reaction than water electrolysis because N2 is hard to react, and I’d expect it to be more expensive than hydrogen from water.
Even if the cells were free, I don’t think their electrolyte is stable for long enough to make that competitive.
Ammonia is cheap to make. If you look at historical prices you can see it can be made for $300/ton with current methods; there have just been price spikes due to supply/demand issues.
Thank you for the answer! One of the things I was curious about was indeed economic competitiveness, so it’s good to know that it won’t be any time soon.
Is there some underlying interest you have, that’s more general?
All knowledge is worth having. But in particular, I’m interested in possible replacements for the Haber-Bosch-LeChatelier process. Yes ammonia is cheap, but we also use a heck of a lot of it. Can you imagine any new process ever bringing down the price further?
Also, from the electro-chemistry side, for this particular paper, what actually does the breaking of the triple bond? Electrolysis of water makes sense to me because I know that water molecules fall apart and come back together all the time in liquid water. So if I think about electrolysis as just kind of nudging the ions to each side of the container and then donating/stealing electrons to/from them once they reach the electrodes, it makes sense to me (this may be oversimplified/wrong). Diatomic nitrogen doesn’t spontaneously fall apart as far as I know? For electrochemical processes in general, is there a large voltage drop at the surfaces of the electrodes?
No need to respond to all or any of these. But you did ask. :)
Water molecules can dissociate into [H3O+] and [OH-] - sort of, they’re complexes with more water with partially-covalent hydrogen bonding. But you can’t just go directly from those to H2 and O2 - for good efficiency you need fancy catalysts and it’s a multistep process starting with OH or H bonding to a metal surface.
Nitrogen conversion generally starts with the end or side of N2 bonding to a metal ion. (Usually the end, IIRC.) The triple bond has electron density far enough away from the nuclei for that to happen. It’s more diffuse and bigger electron density than the orbital of N in NH3 that can get protonated, so it interacts better with positive metal ions bigger than H but smaller than molecules.