Dissociation of CO and H 2O during water–gas shift reaction on carburized Mo/Al 2O 3 catalyst

Abstract

The dissociation of CO and H 2O during the water–gas shift reaction (WGSR) on the 973 K-carburized 4.8 and 8.5 wt% Mo/Al 2O 3 catalysts at 423 K was studied by in situ mass and infrared spectroscopies. It was found that both CO and H 2O were dissociated on the basis of the formation of H 2, 13C 18O, 13C 18O 2 and 13C 18O 16O after the injection of H 2 18O into the 13C 16O stream. Regarding the 12C- and 16O-labeled atoms, 12C 16O 2, 12C 16O 18O and 12C 18O 2 were not formed, but H 2 16O, 12C 16O, 12C 18O and 13C 16O 2 were formed. The H 2 16O, 12C 16O and 13C 16O 2 were formed by the reaction of the dissociated 16O of 13C 16O with the surface carbon or the lattice carbon atom of the Mo oxycarbide. The infrared spectroscopy results for the injection of H 2O into the C 18O flow showed that C 18O had no effect on forming the formate group. The formate and carbonate which were probably formed during the CO 2 hydrogenation were observed when using the 973 K-carburized Mo/Al 2O 3 catalyst and alumina in a stream of CO. The WGSR on the Mo oxycarbide of the carburized Mo/Al 2O 3 catalyst followed the redox route together with the dissociation-association mechanism.