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Article

Competitive Paths for Methanol Decomposition on Pt(111)

Jeff Greeley and Manos Mavrikakis*

Contribution from the Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706

J. Am. Chem. Soc., 2004, 126 (12), pp 3910–3919

DOI: 10.1021/ja037700z

Publication Date (Web): March 5, 2004

In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed.

manos@engr.wisc.edu

Abstract

Periodic, self-consistent, Density Functional Theory (PW91-GGA) calculations are used to study competitive paths for the decomposition of methanol on Pt(111). Pathways proceeding through initial C−H and C−O bond scission events in methanol are considered, and the results are compared to data for a pathway proceeding through an initial O−H scission event [Greeley et al. J. Am. Chem. Soc. 2002, 124, 7193]. The DFT results suggest that methanol decomposition via CH₂OH and either formaldehyde or HCOH intermediates is an energetically feasible pathway; O−H scission to CH₃O, followed by sequential dehydrogenation, may be another realistic route. Microkinetic modeling based on the first-principles results shows that, under realistic reaction conditions, C−H scission in methanol is the initial decomposition step with the highest net rate. The elementary steps of all reaction pathways (with the exception of C−O scission) follow a linear correlation between the transition state and final state energies. Simulated HREELS spectra of the intermediates show good agreement with available experimental data, and HREELS spectra of experimentally elusive reaction intermediates are predicted.

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