This article doesn't clarify why the authors are so surprised about calcium catalyzing this reaction. The Frank-Caro process is based on calcium carbide and is over a hundred years old. Anyone have any insights here?
Reading the Wikipedia page, the Frank-Caro process is a straight forward chemical reaction. Shovel calcium carbide into your reactor. After the reaction is done, shovel calcium cyanamide out of the reactor and on to your farm land to fertilize it. The calcium is "consumed" in the process, in direct proportion to the amount of fertilizer that the reaction creates.
The article talks about Ca3CrN3H as a catalyst, giving the impression that the three nitrogen atoms in the compound stay put; it is different nitrogen atoms that get pumped into the reactor and leave as ammonia to be spread as fertilizer. The calcium remains in place, merely making the reaction go faster.
Catalysis is always a bit mysterious because the catalyst is unchanged by the reaction as though it wasn't involved at all. I don't think that there is any expectation that one can discover catalysts by taking reactants as a hint. Indeed, the classic platinum catalyst in a catalytic converter uses platinum, a very unreactive metal.
This is the bit I was missing, thanks! I knew of the Frank-Caro process but not enough detail to understand the exact reaction. I appreciate your help.
Every industrial advance started with an impractical effect noticed in research. Now that we know a triplet of calcium is helpful, other molecular structures will be tried.
I'm doing catalyst discovery with my side project https://atomictessellator.com, I will be checking to see if I can reproduce and then build off this research. Part of my data pipeline is catalyst activity modelling
No, this doesn't address the hardest part of ammonia production: getting hydrogen. Currently done primarily through gas steam reforming, we're a long way away from electrolysis being commercially viable.
"we're a long way" ignores that we have made progress, and there are several proposals to use Solar and Wind power to do this, and investments in newer reaction chambers. Fortesque mining (Australia) for instance is quite highly invested in this, and believes its close enough to commercially viable to dig ground on production facilities.
I agree it's going to be only viable in a highly distorted market initially, but let's not pretend this isn't normal, when you build out a new industry.
Electrolysis is being performed on an industrial scale already.
Its only serious difficulty is inefficiency, but when the power is free (i.e. renewable production in excess of immediate demand) inefficiency is just a yield problem. Anyway efficiency in excess of 80% has been demonstrated. The key seems to be keeping the product gases from clustering around the electrodes, crowding out the water feedstock. So, pores too small for O2.
As a limit on efficiency, energy lost when the O becomes O2 may be hard to recover. There seems reasonable hope of both H in the H2 coming from the same H2O, given a catalytic electrode surface.
Every large producer of power from renewables will be synthesizing H2 or NH3 for sale during periods of overproduction, regardless of what other storage and backup methods they rely on. The market for those materials will prove unlimited, and tankage and shipping are dirt cheap. Shipping, BTW, is gearing up to transition to LNH3 fuel.
Isn't calcium production one of the major contributors to atmospheric CO2 - something like 8% globally due to cement? Would this process be a net benefit or just move the footprint further back in the chain?
Possibly, but catalysts are usually not required in anything like the same quantity that the process feedstocks are - they are only replaced due to attrition and wear, because the point of a catalyst is that it's not consumed in the desired chemical reaction
The reason cement is a major contributor to CO2 emissions is because of how much cement we produce. I don't know the lifetime or effectiveness of this catalyst, but typically you only need a tiny amount of catalyst to start a reaction and the catalyst material can be used over and over for a long time.
