Palladium dispersion effects on wet methane oxidation kinetics
Artikel i vetenskaplig tidskrift, 2020

The catalytic activity for dry and wet methane oxidation over a series of palladium–alumina catalysts with palladium loadings from 0.23 to 3.6 wt% Pd and systematically varied PdO dispersions from 8.1 to 39% was evaluated by flow reactor measurements and compared with multiscale simulations. The catalysts were prepared by industrially relevant incipient wetness impregnation followed by controlled calcination to provide similar active surface area with a realistic contact between active PdO nanoparticles and the alumina support. Kinetic analysis reveals that in wet conditions, the apparent activation energy for methane oxidation decreases as the PdO particle size increases as opposed to dry conditions where it increases. Active sites at the rim of the PdO particles in contact with the alumina support seem to contribute more to the overall activity under dry conditions but are more sensitive to wet conditions than PdO sites farther away from the rim. This sensitivity is likely due to more severe blocking by hydroxyl groups formed by water dissociation and reversed spillover. Simulations support that PdO bound hydroxyls well may form under the present reaction conditions. It is envisaged that the design of palladium–alumina catalysts for high methane turn-over frequency should target high but not too high PdO dispersion, i.e., the PdO particles should not be smaller than about 2 nm, as to balance water tolerance and palladium utilisation.

Författare

Peter Velin

Chalmers, Kemi och kemiteknik, Tillämpad kemi, Per-Anders Carlsson Group

Carl-Robert Florén

Chalmers, Kemi och kemiteknik, Tillämpad kemi, Polymerteknologi

Magnus Skoglundh

Chalmers, Kemi och kemiteknik, Tillämpad kemi, Polymerteknologi

Agnes Raj

Johnson Matthey

David Thompsett

Johnson Matthey

Gudmund Smedler

Johnson Matthey AB

Per-Anders Carlsson

Chalmers, Kemi och kemiteknik, Tillämpad kemi, Per-Anders Carlsson Group

Catalysis Science and Technology

2044-4753 (ISSN) 2044-4761 (eISSN)

Vol. 10 16 5460-5469

Grundläggande studie av vattens inverkan på oxidationskatalysatorer för biogasapplikationer

Energimyndigheten, 2015-04-01 -- 2019-03-31.

Drivkrafter

Hållbar utveckling

Styrkeområden

Transport

Materialvetenskap

Ämneskategorier

Kemiteknik

Materialkemi

DOI

10.1039/d0cy00734j

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Senast uppdaterat

2020-10-12