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A computational study of direct CO₂ hydrogenation to methanol on Pd surfaces

Kowalec, Igor; Kabalan, Lara; Catlow, C Richard A; Logsdail, Andrew J; (2022) A computational study of direct CO₂ hydrogenation to methanol on Pd surfaces. Physical Chemistry Chemical Physics , 16 (24) pp. 9360-9373. 10.1039/d2cp01019d. Green open access

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Abstract

The reaction mechanism of direct CO2 hydrogenation to methanol is investigated in detail on Pd (111), (100) and (110) surfaces using density functional theory (DFT), supporting investigations into emergent Pd-based catalysts. Hydrogen adsorption and surface mobility are firstly considered, with high-coordination surface sites having the largest adsorption energy and being connected by diffusion channels with low energy barriers. Surface chemisorption of CO2, forming a partially charged CO2δ−, is weakly endothermic on a Pd (111) whilst slightly exothermic on Pd (100) and (110), with adsorption enthalpies of 0.09, −0.09 and −0.19 eV, respectively; the low stability of CO2δ− on the Pd (111) surface is attributed to negative charge accumulating on the surface Pd atoms that interact directly with the CO2δ− adsorbate. Detailed consideration for sequential hydrogenation of the CO2 shows that HCOOH hydrogenation to H2COOH would be the rate determining step in the conversion to methanol, for all surfaces, with activation barriers of 1.41, 1.51, and 0.84 eV on Pd (111), (100) and (110) facets, respectively. The Pd (110) surface exhibits overall lower activation energies than the most studied Pd (111) and (100) surfaces, and therefore should be considered in more detail in future Pd catalytic studies.

Type: Article
Title: A computational study of direct CO₂ hydrogenation to methanol on Pd surfaces
Open access status: An open access version is available from UCL Discovery
DOI: 10.1039/d2cp01019d
Publisher version: https://doi.org/10.1039/d2cp01019d
Language: English
Additional information: This article is licensed under a Creative Commons Attribution 3.0 Unported Licence (http://creativecommons.org/licenses/by/3.0/).
UCL classification: UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL
URI: https://discovery.ucl.ac.uk/id/eprint/10147033
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