291437 Synthesis of Tungsten Carbide From Tungsten Oxide Precursors in the Presence of Added Metals

Monday, October 29, 2012
Hall B (Convention Center )
Sarah W. Paleg, Energy, Environmental, and Chemical Engineering, Washington University in St. Louis, St. Louis, MO, Joshua Schaidle, Chemical Engineering, The University of Michigan, Ann Arbor, MI, Daniel A. Ruddy, Chemical and Materials Science Center, National Renewable Energy Laboratory, Golden, CO and Jesse E. Hensley, National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO

Transition metal carbides are renowned for being low-cost, highly-active catalysts with similarities to Group VIII catalysts. Tungsten carbide (W2C) is an active catalyst for many of the same reactions as Pt metal, including water formation from hydrogen and oxygen, methane decomposition, ammonia decomposition, and mixed methanol/methane formation from syngas. W2C is therefore an attractive replacement for Pt since it is scarcer and more expensive than tungsten carbide. The temperature-programmed reaction (TPR) method was used to synthesize W2C by the carburization of tungsten oxide (WO3) powder with CH4/H­2 gas, and then the same TPR procedure was used with WO3 powder with added metals (Pt, K, Fe, Pd, and Mg). When metal was added to the WO3 precursor, the XRD pattern showed WO2 and W-metal (no W2C) in the final solid product. During TPR, the carburization steps were observed by monitoring the mass spectrometry signals of H2O, CO, and CO2. The addition of metal to the precursor generally shifted the peaks in these signals to lower temperatures, with the most significant shifts observed for precursors with added noble metals.

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