(127d) Isotopic Transient Analysis of CO Hydrogenation Over Supported Molybdenum Carbide Nanoclusters

The catalytic conversion of synthesis gas derived from coal, natural gas or renewable biomass is a promising route to produce alternative energy carriers and chemical feedstocks, and molybdenum carbide is potentially an effective catalyst for the reaction provided suitable promoters and activity gains are realized. The product distribution from CO hydrogenation over molybdenum carbide favors production of linear hydrocarbons via Fischer-Tropsch synthesis, whereas promotion of molybdenum carbide with alkali metals shifts the product distribution toward the production of mixed alcohols.  In this study, nanometer-sized clusters of Mo₂C were supported on alumina and characterized by a variety of techniques, including X-ray absorption spectroscopy, electron microscopy and diffuse reflectance infrared spectroscopy of adsorbed CO.  Steady state isotopic transient analysis of the CO hydrogenation reaction over supported Mo₂C catalysts, with and without Rb promoter, was then used to elucidate fundamental kinetic parameters such as the intrinsic turnover frequency of the reaction and the coverage of surface intermediates leading to products.  Results from transient kinetic analysis and spectroscopic characterization will be used to explain the observed influence of Rb promoter on the steady state product distribution during CO hydrogenation.