Researchers at Purdue University have discovered a novel technique for producing hydrogen from water and organic material.
Although not yet evaluated for economic or operational feasibility on a large scale, the technique requires only water, a catalyst based on the metal rhenium and an organic liquid called an organosilane, which can be stored and transported easily.
We have discovered a catalyst that can produce ready quantities of hydrogen without the need for extreme cold temperatures or high pressures, which are often required in other production and storage methods. It is possible that this technique could lead to fuel cells that are safe, efficient and not dependent on fossil fuels as their energy source.—Mahdi Abu-Omar, associate professor of chemistry
Abu-Omar’s research team published their findings today (Wednesday, Aug. 31) in the Journal of the American Chemical Society.
The main highlights of the reaction are quantitative hydrogen yields, low catalyst loading, ambient conditions, high selectivity for silanols, water as the only co-reagent, and no solvent requirement. The amount of hydrogen produced is proportional to the water stoichiometry. Thus, reaction mixtures of polysilyl organics such as HC(SiH3)3 and water contain potentially > 6% by weight hydrogen.
The discovery was accidental. The research team was working on a different problem, trying to find useful catalysts to convert silicon-based fluids (organosilanes) into silanols, another substance of value in the chemical industry.
Abu-Omar’s team took a compound based on rhenium, a comparatively rare metal often obtained while mining copper, and added it to the organosilane in the presence of water. Over the course of an hour, the organosilane changed completely into silanol, leaving the water and rhenium catalyst unchanged. But the team also noticed there was a gas bubbling from the mixture.
It turned out to be pure hydrogen. The reaction is not only efficient at creating silanol, but it also generates hydrogen at a high rate in proportion to the amount of water.—Abu-Omar
The team estimates that about 7 gallons each of water and organosilane could combine to produce 6.5 pounds (2.9 kilograms) of hydrogen. With current fuel cell technology, that would work out roughly to a 150- to 170-mile range.
The big question is, of course, whether it would be economically viable to create organosilane fuels in the quantities necessary to power a world full of cars. As of right now, there simply isn’t enough demand to make more than small volumes of this liquid, and while it’s a relatively easy process, it’s not dirt cheap either.
I think the big point here is that hydrogen can be produced from water and a form of organic matter. If this rhenium-based catalyst can do the trick on organosilanes, perhaps we can find other catalysts that can generate hydrogen from garbage, or from biomass left over from the harvest.
“Hydrogen Production from Hydrolytic Oxidation of Organosilanes Using a Cationic Oxorhenium Catalyst”, J. Am. Chem. Soc., 127 (34), 11938 -11939, 2005.