Dry reforming of methane over Pt/PrCeZrO catalyst: Kinetic and mechanistic features by transient studies and their modeling

The effect of pretreatment and Pt content on the catalytic properties as well as mechanistic features of DR were investigated for structured catalysts comprised of Pt supported on CeO2-ZrO2 oxide doped by Pr. Progressive reduction of cationic Pt species by the reaction feed lowers the activity in CH4 dry reforming while accelerating the reverse water gas shift reaction catalyzed only by Pt-0, which then decreases progressively the H-2/CO ratio in the effluent. This process is counteracted by the mobility of surface oxygen supplying oxygen atoms to reduced Pt centers thus ensuring their reoxidation and generating in parallel surface oxygen vacancies for the dissociation of CO2. A mathematical model and software were developed for numerically studying the transients of the complex catalytic reactions. The processing of experimental data was fulfilled taking into account the importance of cationic forms of Pt, reactivity of carbonate complexes coordinated to these cations and oxygen surface/bulk diffusion. A quantitative evaluation of the density of catalyst's active sites and their coverage by reactive species was accomplished and the rates both of the lattice oxygen diffusion and main stages of the catalytic reaction were estimated. (C) 2011 Elsevier B. V. All rights reserved.