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/12 CeO2–Al2O3. TAP pulse experiments demonstrated that both catalysts dissociate methane at 773 K 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 5 s, 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.