Performance and operating characteristics of methanol steam-reforming catalysts for on-board fuel-cell hydrogen production

Copper supported on various oxides has been found to be the most active catalyst for methanol steam reforming. These catalysts are highly selective and produce a gas mixture consisting almost exclusively of hydrogen, carbon dioxide and unreacted excess steam with only small, but undesirable, concentrations of carbon monoxide and unreacted methanol. The catalyst is loaded into the reformer in a fully oxidised state and must be activated by reducing the copper before being used. Reduction with CO or reduction with steam-methanol mixture results in better initial activity than reduction with hydrogen. Once on line, the catalyst activity declines with time in operation. There is often an initial period of rapid deactivation which is invariably followed by a slow steady decline in activity. The long-term rate of deactivation increases with temperature which is typical for deactivation due to sintering. For a given temperature, all Cu/ZnO/Al2O3 catalysts (the most common oxide combination) appear to deactivate at the same rate. The decrease in rate of CO production with time on line, however, is unique for each catalyst formulation. The performance for hydrogen production is not significantly affected by operating problems such as overpressure, intermittent shutdowns or exposure to temperatures as high as 300 degrees C for periods of less than 10 hours.