CATALYTIC COMBUSTION OF METHANE OVER SUPPORTED PALLADIUM CATALYSTS .1. ALUMINA SUPPORTED CATALYSTS

A series of Pd/Al2O3 catalysts were tested, under continuous-flow conditions, for their activity towards methane combustion in an oxygen rich atmosphere. It was found that, under reaction conditions, catalysts became more active with time-on-stream with rate constants increasing by up to 100 fold. This activation effect could be observed over a short period or for many tens of hours. Both γ-and δ-alumina-supported catalysts exhibited activation and the effect was not eliminated by vigorous calcination of the catalysts. The enhanced activities were not due to a redispersion of the active phase or thermal effects in the catalyst bed. No clear relationship between palladium particle size and rate of reaction was dicernible. © 1990.