PtMo Bimetallic Catalysts Synthesized by Controlled Surface Reactions for Water Gas Shift

Supported PtMo bimetallic catalysts were prepared by controlled surface reactions (CSR) and studied for water gas shift (WGS) at 543 K. Carbon and silica supports were used for the preparation of monometallic Pt catalysts, and Mo was deposited onto these catalysts by reaction with cycloheptatriene molybdenum tricarbonyl ((C7H8)­Mo­(CO)3). Catalysts were characterized by CO chemisorption, inductively coupled plasma-atomic emission spectroscopy (ICP-AES), STEM/EDS, and XAS analysis. We report that carbon-supported Pt nanoparticles are saturated with Mo species at a Mo:Pt atomic ratio of 0.32. Molybdenum has a strong promotional effect in these catalysts, increasing the TOF by up to a factor of more than 4000. Silica-supported catalysts were found to be more active, but the TOF promotional effect of Mo was smaller than for the carbon-supported catalysts at 15. EDS analyses and activity studies showed that the formation of bimetallic catalysts was therefore more efficient using the carbon support. The active sites for WGS are suggested to be at the interface between Pt atoms and Mo moieties that are possibly in an oxidized form.