Investigation of the water activation step in the water gas shift reaction mechanism on ceria-supported platinum catalysts

J. VECCHIETTI; M. CALATAYUD; DARIO STACCHIOLA; DELGADO, JUAN JOSE; ADRIAN BONIVARDI; COLLINS, SEBASTIAN

Lyon

Congreso; 11th European Congress on Catalysis - EuropaCat-XI; 2013

The need for high purity hydrogen to feed fuel cells to produce electricity has prompted the investigation of active catalysts for the low-temperature water gas shift reaction (WGS). In this context metal supported (gold and platinum) ceria-based catalysts are among the best candidates to meet these requirements [1]. WGS is a prototypi-cal catalytic reaction, which in spite of its apparent simplicity has shown a rather unique complexity. An impressive volume of investigations have been carried out in order to understand the elementary reactions steps at an atomistic level. However, up to now a consensus concerning the reaction mechanism has not been reached in the literature. Two apparently contradictory reaction pathways are generally discussed [1]: i) the redox and ii) the associative mechanisms (involving carbonate, formate and carboxylate). Both mechanisms involve as active sites the metal particles and the oxidic support, that is, a bi-functional mechanism. The step of water dissociation has received less attention in the investigation of the WGS mechanism. However, this reaction step has been reported as energetically important, and in some cases as the rate-determining step. In this work we reported the investigation of the activation of the water molecule in a series of well characterized platinum catalyst supported on ceria and ceria doped with gallium which exhibit different redox properties.