Density functional theory study of the partial oxidation of methane to methanol on Au and Pd surfaces

Nasrallah, Ali, Engel, Julien ORCID: https://orcid.org/0000-0002-1235-4784, Catlow, C. Richard A. ORCID: https://orcid.org/0000-0002-1341-1541 and Willock, David J. ORCID: https://orcid.org/0000-0002-8893-1090 2021. Density functional theory study of the partial oxidation of methane to methanol on Au and Pd surfaces. Journal of Physical Chemistry C 125 (34) , 18770–18785. 10.1021/acs.jpcc.1c06206

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Abstract

The partial oxidation of methane to methanol has been a goal of heterogeneous catalysis for many years. Recent experimental investigations have shown how AuPd nanoparticle catalysts can give good selectivity to methanol with only limited total oxidation of CH4 using hydrogen peroxide as an oxidant in aqueous media. Interestingly, the use of colloidal nanoparticles alone, without a support material, leads to efficient use of the oxidant and the possibility of introducing oxygen from O2(g) into the CH3O2H primary product. This observation indicates that a radical mechanism is being initiated by H2O2 but then the oxygen addition step, catalyzed by these nanoparticles, can incorporate O2(ads). In this contribution, we use density functional theory (DFT) to study the elementary steps in the partial oxidation of methane to methanol using H2O2 as a radical initiator and molecular oxygen as an oxidant over the low index surfaces of Pd and Au. We are able to show that pure Pd nanoparticles are prone to oxidation by O2(g), whereas the competitive adsorption of water on Au surfaces limits the availability of O2(ads). Calculations with Au added to Pd or vice versa show that both effects can be alleviated by using mixed metal surfaces. This provides a rationalization of the need to use alloy nanoparticles experimentally, and the insights from these results will aid future catalyst development.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Chemistry Cardiff Catalysis Institute (CCI)
Publisher:	American Chemical Society
ISSN:	1932-7447
Funders:	EPSRC and Cardiff University
Date of First Compliant Deposit:	30 September 2021
Date of Acceptance:	23 July 2021
Last Modified:	07 Nov 2023 19:53
URI:	https://orca.cardiff.ac.uk/id/eprint/144568

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