COMPACT HYDROGEN-PRODUCTION SYSTEMS FOR SOLID POLYMER FUEL-CELLS

Generally there are several ways to produce hydrogen gas from carbonac eous fuels like natural gas, oil or alcohols. Most of these processes are designed for large-scale industrial production and are not suitabl e for a compact hydrogen production system (CHYPS) in the power range of 1 kW. In order to supply solid polymer fuel cells (SPFC) with hydro gen, a compact fuel processor is required for mobile applications. The produced hydrogen-rich gas has to have a low level of harmful impurit ies; in particular the carbon monoxide content has to be lower than 20 ppmv. Integrating the reaction step, the gas purification and the hea t supply leads to small-scale hydrogen production systems. The steam r eforming of methanol is feasible at copper catalysts in a low temperat ure range of 200-350 degrees C. The combination of a small-scale metha nol reformer and a metal membrane as purification step forms a compact system producing high-purity hydrogen. The generation of a SPFC hydro gen fuel gas can also be performed by thermal or catalytic cracking of liquid hydrocarbons such as propane. At a temperature of 900 degrees C the decomposition of propane into carbon and hydrogen cakes place. A fuel processor based on this simple concept produces a gas stream wit h a hydrogen content of more than 90 vol.% and without CO and CO2. (C) 1998 Elsevier Science S.A.