Supported Nanostructured Mo_xC Materials for the Catalytic Reduction of CO₂ through the Reverse Water Gas Shift Reaction

Mo_xC-based catalysts supported on γ-Al₂O₃, SiO₂ and TiO₂ were prepared, characterized and studied in the reverse water gas shift (RWGS) at 548-673 K and atmospheric pressure, using CO₂:H₂ = 1:1 and CO₂:H₂ = 1:3 mol/mol reactant mixtures. The support used determined the crystalline Mo_xC phases obtained and the behavior of the supported nanostructured Mo_xC catalysts in the RWGS. All catalysts were active in the RWGS reaction under the experimental conditions used; CO productivity per mol of Mo was always higher than that of unsupported Mo₂C prepared using a similar method in the absence of support. The CO selectivity at 673 K was above 94% for all the supported catalysts, and near 99% for the SiO₂-supported. The Mo_xC/SiO₂ catalyst, which contains a mixture of hexagonal Mo₂C and cubic MoC phases, exhibited the best performance for CO production.