Wednesday, December 16, 2009

New insight into the conversion of methane to ethane by palladium-based catalysts

As part of CENTC's continuing attempts to develop catalytic processes to utilize methane gas as a potential source of fuel and other chemicals, CENTC investigators James Mayer (University of Washington) and Melanie Sanford (University of Michigan) have reported a better understanding of the way certain palladium-based catalysts release methane to form ethane. The studies, conducted collaboratively by the Mayer and Sanford research groups, were reported as a Communication in the Journal of the American Chemical Society (JACS) on October 13, 2009.

Sanford and Mayer investigated the ferrocenium-induced elimination of palladium-bound CH3 to give ethane in order to determine which of three possible pathways was a likely route for the reaction to take. A series of experiments were carried out that suggested the reaction did not involve methyl radicals and did involve a Pd(IV) intermediate. Further reactions were carried out at low temperature (-80° C) and the Pd(IV) intermediate was observed by nuclear magnetic resonance (NMR) spectroscopy. Additional experiments with other oxidants suggested that Ag+ follows a similar mechanism but benzoquinone behaves differently.

The studies conducted by Mayer and Sanford are part of an ongoing project by CENTC researchers to develop catalysts for the direct oxidative dimerization or oligomerization of methane. The overall goal of this project is to address the need to form higher alkanes from methane via processes that do not involve energy-intensive cracking or steam reforming to syngas.

"Oxidatively Induced Reductive Elimination from (tBu2bpy)Pd(Me)2: Palladium(IV) Intermediates in a One-Electron Oxidation Reaction" Michael P. Lanci, Matthew S. Remy, Werner Kaminsky, James M. Mayer and Melanie S. Sanford, J. Am. Chem. Soc., 2009, 131 (43), pp 15618-15620

[DOI: 10.1021/ja905816q]

Read the JACS Communication

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