Adsorption and Reaction of CO 2 on Mo 2 C Catalyst

The reaction between CO 2 and ZSM-5- and SiO 2 -supported Mo 2 C catalysts, found to be active in the aromatization of methane, has been studied in a flow and static system by measuring changes in the gas composition. The reaction was also followed with X-ray photoelectron spectroscopy. The decomposition of CO 2 occurred above 823 K to give CO and O atoms. Using 13 CO 2 it was possible to establish that a fraction of O atoms oxidized the carbon of Mo 2 C into CO, the other part reacted with Mo to give MoO x species. The ratio of 13 CO/ 12 CO varied between 5 and 6.0. XPS study confirmed the oxidation of Mo resulting in the formation of Mo ions of various oxidation states. Although the dominant oxidation state is Mo 6+ at every temperature, Mo 4+ and Mo 5+ were present in the sample even after the reaction at 1073 K. The reaction proceeded at a faster rate on Mo 2 C/ZSM-5 than on Mo 2 C/SiO 2 .