Renewable hydrogen from nonvolatile fuels by reactive flash volatilization.

Droplets of nonvolatile fuels such as soy oil and glucose-water solutions can be flash evaporated by catalytic partial oxidation to produce hydrogen in high yields with a total time in the reactor of less than 50 milliseconds. Pyrolysis, coupled with catalytic oxidation of the fuels and their fragments upon impact with a hot rhodium-cerium catalyst surface, avoids the formation of deactivating carbon layers on the catalyst. The catalytic reactions of these products generate approximately 1 megawatt of heat per square meter, which maintains the catalyst surface above 800 degrees C at high drop impact rates. At these temperatures, heavy fuels can be catalytically transformed directly into hydrogen, carbon monoxide, and other small molecules in very short contact times without the formation of carbon.

Renewable hydrogen from ethanol by autothermal reforming.

Ethanol and ethanol-water mixtures were converted directly into H2 with approximately 100% selectivity and >95% conversion by catalytic partial oxidation, with a residence time on rhodium-ceria catalysts of <10 milliseconds. Rapid vaporization and mixing with air with an automotive fuel injector were performed at temperatures sufficiently low and times sufficiently fast that homogeneous reactions producing carbon, acetaldehyde, ethylene, and total combustion products can be minimized. This process has great potential for low-cost H2 generation in fuel cells for small portable applications where liquid fuel storage is essential and where systems must be small, simple, and robust.