Chemical News

Tuesday, July 15, 2008

Aqueous Phase Reforming for Hydrogen Production

Aqueous-phase reforming (APR) produces hydrogen from biomass-derived oxygenated compounds such as glycerol, sugars and sugar alcohols. APR is unique in that the reforming is done in the liquid phase. The process generates hydrogen without volatilizing water, which represents major energy savings.

Furthermore, it occurs at temperatures and pressures where the water-gas shift reaction is favorable, making it possible to generate hydrogen with low amounts of CO in a single chemical reactor. By taking place at low temperatures, the process also minimizes undesirable decomposition reactions typically encountered when carbohydrates are heated to elevated temperatures. In another mode, the reactor and catalysts can be altered to allow generation of high-energy hydrocarbons (propane, butane) from biomass-derived compounds.

A multitude of technologies handle the separation of carbohydrates from biomass, and the appropriateness of a feedstock for this process depends on determining the proper separation technology. Some feedstocks, like those listed above, are already aqueous carbohydrate streams. Unlike other hydrogen-producing technologies, APR requires no non-renewable resources and is emissions neutral, and unlike steam reformation processes, APR produces hydrogen from liquid-phase solutions, resulting in considerable energy savings.