Fundamental mechanistic studies of H2O2 direct catalytic synthesis and decomposition

A. Plauck1, A. C. Alba-Rubio1, E. Stangland2, J. A. Dumesic1, M. Mavrikakis1

1Department of Chemical & Biological Engineering, University of Wisconsin â?? Madison

2Core Research and Development, The Dow Chemical Company, Midland MI

Hydrogen peroxide (H2O2) is a versatile and environmentally benign oxidizing agent that has the potential to decrease the environmental impact of numerous manufacturing processes â?? both chemical and non-chemical. Currently, the anthraquinone process accounts for over 95% of worldwide H2O2 production but is complex and only implemented on the large scale[1]. This has limited the introduction and expansion of new processes that would benefit from on-site H2O2 production.
Here we focus on an alternative process, the direct synthesis of H2O2, wherein H2 and O2 are combined in a single reactor over a transition metal catalyst. Although Pd-based catalysts for the direct synthesis of H2O2 have been a subject of intense study, especially those modified with Au[2,3], there is still an inadequate understanding of the fundamental details of the active site(s) and elementary transformations. To that end, we combine experimental reaction kinetics studies on a promoter-free Pd catalyst with periodic, self-consistent Density Functional Theory (DFT) calculations on multiple Pd facets to construct a mean-field microkinetic model. This presentation will focus on fundamental mechanistic aspects determining synthesis selectivity to H2O2, and the H2O2 decomposition reaction on Pd-based catalysts.

[1] Centi, G., Perathoner, S., & Abate, S. Direct Synthesis of Hydrogen Peroxide: Recent Advances in Modern Heterogeneous Oxidation Catalysis: Design, Reactions and Characterization. Wiley-VCH, Weinheim, 2009.

[2] Edwards, J. K. et al. Switching Off Hydrogen Peroxide Hydrogenation in the Direct Synthesis Process.

Science 323, 1037-1041 (2009).

[3] Campos-Martin, J. M., Blanco-Brieva, G. & Fierro, J. L. G. Hydrogen Peroxide Synthesis: An Outlook beyond the Anthraquinone Process. Angewandte Chemie-International Edition 45, 6962-6984 (2006).