Transient Mechanistic Studies of Methane Steam Reforming over Ceria-Promoted Rh/Al2O3 Catalysts

Transient-pulse experiments in temporal-analysis-of-product (TAP) and conventional mode were performed to determine elementary reaction steps involved in the methane steam reforming reaction over Rh/Al2O3 and Rh/12CeO(2)-Al2O3. TAP pulse experiments demonstrated that both catalysts dissociate methane at 773K leading to hydrogen, carbon, and CHx adspecies. Conventional transient pulse experiments with alternating methane/argon and water pulses with a delay between them of 86, 73, and 5s, respectively, showed that the reactivity of adspecies over the promoted and nonpromoted catalysts decrease with time. Ceria catalyzes the oxidation of carbon species by water.