The deposition of Au on surfaces of TiC and MoC produces catalysts that are very efficient for desulfurization processes and the production of hydrogen through the low-temperature water-gas shift reaction. Au atoms in contact with TiC(001) and MoC(001) undergo a charge polarization that substantially enhances the chemical reactivity of the admetal. For example, the TiC and MoC carbides have difficulty binding the thiophene molecule and are very poor as hydrodesulfurization (HDS) catalysts. The addition of small Au nanoparticles is an efficient way for enhancing the HDS activity of these systems. The creation of a gold-carbide interface leads to an enhancement in the adsorption energy of thiophene and helps in the dissociation of H2 to produce the hydrogen necessary for the hydrogenolysis of C-S bonds and the removal of sulfur in the HDS process. Furthermore, it has been found that the metal-carbide interfaces present in the Au/TiC and Au/MoC systems are very good catalysts for the low temperature water-gas shift (WGS, CO + H2O à H2 + CO2) reaction with turnover frequencies order of magnitude larger than those observed for conventional metal/oxide catalysts. Experimental and theoretical studies point to an associative WGS mechanism, with HOCO as a key intermediate formed in the gold-carbide interface.

Novel metal carbide catalysts for desulfurization and the low temperature water-gas shift  reaction

251st National Meeting (2016)

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