Chemisorbed oxygen or surface oxides steer the selectivity in Pd electrocatalytic propene oxidation observed by operando Pd L-edge X-ray absorption spectroscopy

Friday 21 May 21
Controlled electrochemical oxidation of hydrocarbons to desired products is an attractive approach in catalysis. Here we study the electrochemical propene oxidation under operando conditions using Pd L-edge X-ray absorption spectroscopy (XAS) as a sensitive probe to elucidate surface processes occurring during catalysis. 

Together with ab initio multiple-scattering calculations, our XAS results enable assignment of characteristic changes of the Pd L-edge intensity and energy position in terms of a mechanistic understanding of the selective oxidation of propene. The results, supported by electrochemical density functional theory DFT simulations, show that in the potential range of 0.8–1.0 V vs. the reversible hydrogen electrode (RHE), selective oxidation of propene to acrolein and acrylic acid occurs on the metallic Pd surface. These reactions are proposed to proceed via the Langmuir–Hinshelwood mechanism. In contrast, for the potential range of 1.1–1.3 V vs. RHE, selective oxidation of propene to propylene glycol takes place on a Pd oxide surface.

Sergey Koroidov, Anna Winiwarter, Oscar Diaz-Morales, Mikaela Görlin, Joakim Halldin Stenlid, Hsin-Yi Wang, Mia Börner, Christopher Matthew Goodwin, Markus Soldemo, Lars Gunnar Moody Pettersson, Jan Rossmeisl, Tony Hansson, Ib Chorkendorff and  Anders Nilsson

Catal. Sci. Technol., 2021,11, 3347-3352

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