Newcastle team claims first thermodynamically-reversible chemical reactor producing hydrogen from water

One of the biggest barriers towards establishment of a “hydrogen economy” is the availability of hydrogen gas. Although it is the most abundant element in the universe, on earth it is always present as part of a compound, which must be broken apart to retrieve it. This requires energy, and if hydrogen is to be a low carbon energy carrier, that energy must itself be low carbon. Currently, most hydrogen is produced from hydrocarbons or by electrolysis of water, both of which generally use energy generated with the production of carbon dioxide.
The Newcastle team, led by chemical engineer Prof Iain Metcalfe, has developed a process which avoids mixing reactant gases by transferring oxygen between reactant streams via a solid-state oxygen reservoir. Reacting water and carbon dioxide to generate hydrogen and carbon monoxide, the process operates close to an equilibrium state, resulting in a pure stream of hydrogen which does not require additional separation processes.
The oxygen reservoir retains a “chemical memory” of the conditions to which has been exposed, and therefore Metcalfe has dubbed it a hydrogen memory reactor. In a paper in Nature Chemistry, he and colleagues from the Universities of Durham and Edinburgh, along with European synchrotron research facility in France, describe how the reactor can be powered by renewable energy, making it a source of zero carbon hydrogen.
“Chemical changes are usually performed via mixed reactions whereby multiple reactants are mixed together and heated. But this leads to losses, incomplete conversion of reactants and a final mixture of products that need to be separated,” Metcalfe said. “With our Hydrogen Memory Reactor we can produce pure, separated products. You could call it the perfect reactor.”
The oxygen reservoir is composed of a perovskite, a type of transition metal-containing mineral more often associated with solar cells. “This reservoir is able to remain close to equilibrium with the reacting gas streams because of its variable degree of non-stoichiometry and thus develops a ‘chemical memory’ that we employ to approach reversibility” the researchers explain.
Another advantage of the system is that it accomplishes all the stages of the reaction in a single unit, unlike conventional hydrogen production which requires two reactors and a separation stage, Metcalfe explained. This is particularly significant because the purification stage of traditional processes is often costly and energy intensive. Because the gaseous reactants never mix, carbon cannot be carried over into the hydrogen stream, avoiding contamination of the product which is a serious problem if the hydrogen is to be used, for example, in a fuel cell. The system also produces an unusually high conversion rate, unlike other processes where only a relatively small percentage of the hydrogen in the water stream is separated.
But what happens to the CO2 and how much is produced per m3 of Hydrogen?
The CO2 is coverted to CO. “Water shift” is a very well-known reaction, and CO is a useful feedstock for building hydrocarbons (ironically, it’s usually mixed with hydrogen; the mixture is known as syngas)
This video explains the principles of the process described. http://nuvision.ncl.ac.uk/Play/18143
Does the “water” being used have to have a known purity so no solids [suspended or dissolved] affect the reaction and keep the output as pure/clean as possible?
Can any of the Syngas then be used in Solid Oxide fueled generators?
Is it a misprint or am I missing something? It says hydrogen and carbon monoxide are reacted to generate hydrogen and carbon dioxide – Surely it should say water and carbon monoxide? Also how is the CO produced in the first place from CO2 – does that not require energy? No efficiency numbers are quoted, it would be instructive to see how much of a breakthrough this is if they told us how much energy is required to produce 1Kg of hydrogen compared with conventional hydrogen production.
It’s a misprint, which we will correct shortly.
Apparently, the CO2 is ready for capture, to pipeline (although I would not certify in any way this is food-grade CO2), or release to atmosphere in a greenhouse without the nasty carbon monoxide contaminant. If the hydrogen is from fossil fuel or syn-fuel, why bother, especially if the conversion is to be on-board a moving vehicle? I suspect there will be far better ways to do this, although the attraction here is high throughput, with high quality hydrogen stream available to fuel cell.
Why bother with hydrogen at all when the new thin-film magnesium fuel cell battery will far surpass this performance level and range available? Brits need look no further than the proposed magnesium economy of Japan (and the US) to find a better mouse trap.
Sounds promising,. I would not be overly concerned about the Carbon dioxide produced, as long as it is either captured or the effects of its release mitigated. The fact that the process consumes Carbon Monoxide is a big benefit. As long as we can mitigate the problems with the use of hydrogen this looks like a better alternative to electric cars that rely on batteries as the tank can be topped up the same way and time as we do now.
How about telling us how it works? Just another reprinted “gee whiz” press release? What form of renewable energy does it use? Electricity or heat?
How about reading the linked paper?
Can we share the hell out of this, we need innovation in the energy sector.
Para 2 line 3 reads
“Reacting hydrogen and carbon monoxide to generate hydrogen and carbon dioxide”
this seems to be missing something.
Should this be
“reacting water and carbon monoxide to generate hydrogen and carbon dioxide”
?
It should; thanks for catching that.
In that case it is the water gas shift reaction (discovered 1780) https://en.wikipedia.org/wiki/Water-gas_shift_reaction … & it is also worth remembering Hess’s Law https://www.bbc.com/bitesize/guides/z8p72hv/revision/4
If it works on an industrial international scale then great! But the words – “retains a “chemical memory” do not inspire confidence similar to the arguments in favour of some homeopathic medicine, where the active components are diluted so they become unmeasurable, coupled with scepticism about perpetual motion! i would like to thnk I am wrong.
Much of the arguments about moving away from fossil fuels are focussing on the increased CO2 emissions. If CO2 is a by-product of hydrogen production and it is released without processing then we aren’t really gaining anything. A novel way of hydrogen being produced perhaps but the focus should actually be on what we do with the CO2.
After watching the video, this research seems – to me – headed 180° in the wrong direction, we shouldn’t be producing hydrogen from fossil fuels no matter how efficient or elegant the method. We already have a carbon-free way of producing hydrogen: electrolysis of water using renewables or nuclear. Instead, react this hydrogen with CO2 captured from an intractable (or at least difficult to mitigate) industry like cement manufacture. Use the REVERSE water gas shift reaction CO2+H2 = CO+H2O and react the CO with more (renewable) H2 to produce aviation fuel (another difficult-to-decarbonise sector), using Fischer-Tropsch synthesis. The CO2 still ultimately doesget released by the aircraft but at least we’ve had 2 economic benefits per tonne released (or put another way 50% reduction in the carbon footprint)