Water Inhibition in Methane Oxidation over Alumina Supported Palladium Catalysts
Journal article, 2019

In situ diffuse reflectance infrared Fourier transform spectroscopy has been used to distinguish surface hydroxyl groups on Al2O3 and PdO/Al2O3 model catalysts calcined at 500-900 °C. Employing the operando approach, the formation of surface hydroxyl groups has been correlated to the methane oxidation activity for PdO/Al2O3 catalysts using a PdO powder sample as reference. The results show that the alumina support stabilizes active PdO particles leading to enhanced apparent methane turnover frequency (TOF), which decreases slowly in dry conditions due to alumina hydroxylation. Wet conditions cause severe hydroxylation that is detrimental for the methane TOF. The hydroxylation follows two different routes, i.e., spillover of hydrogen-containing species to the PdO-Al2O3 boundary and/or the close proximity of the supported PdO particles and under wet conditions also dissociation of gas phase water on the entire alumina surface. Both hydroxylation routes obey varying kinetics such that near saturation is reached quickly (minutes) followed by a continuous slow growth for prolonged exposure times (hours). At low temperatures, inhibition of palladium active sites on the rim of the PdO particles close to alumina seems to be of particular importance for the observed detrimental effect of water, whereas water induced morphological changes (no sintering observed) of the PdO particles play a minor role.

Author

Peter Velin

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Per-Anders Carlsson Group

Martin Ek

Lund University

Magnus Skoglundh

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Polymer Technology

Andreas Schaefer

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry

Agnes Raj

Johnson Matthey

David Thompsett

Johnson Matthey

Gudmund Smedler

Johnson Matthey AB

Per-Anders Carlsson

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Per-Anders Carlsson Group

Journal of Physical Chemistry C

1932-7447 (ISSN) 1932-7455 (eISSN)

Vol. 123 42 25724-25737

Subject Categories

Materials Chemistry

Other Chemical Engineering

Other Chemistry Topics

DOI

10.1021/acs.jpcc.9b07606

More information

Latest update

11/12/2019