The transformation of methane into methanol or higher alcohols at moderate temperature and pressure conditions is of great environmental interest and remains a challenge despite many efforts. Extended surfaces of metallic nickel are inactive for a direct CH4 → CH3OH conversion. This experimental and computational study provides clear evidence that low Ni loadings on a CeO2(111) support can perform a direct catalytic cycle for the generation of methanol at low temperature using oxygen and water as reactants, with a higher selectivity than ever reported for ceria-based catalysts. On the basis of ambient pressure X-ray photoemission spectroscopy and density functional theory calculations, we demonstrate that water plays a crucial role in blocking catalyst sites where methyl species could fully decompose, an essential factor for diminishing the production of CO and CO2, and in generating sites on which methoxy species and ultimately methanol can form. In addition to water-site blocking, one needs the effects of metal-support interactions to bind and activate methane and water. These findings should be considered when designing metal/oxide catalysts for converting methane to value-added chemicals and fuels.

Chemistry Department Brookhaven National Laboratory Upton New York 11973 United States

Department of Surface and Plasma Science Faculty of Mathematics and Physics Charles University Prague Czech Republic

Facultad de Ciencias Universidad Central de Venezuela Caracas 1020 A Venezuela

Instituto de Catálisis y Petroleoquímica CSIC C Marie Curie 2 28049 Madrid Spain

Instituto de Fisica Rosario CONICET UNR Bv 27 de Febrero 210bis S2000EZP Rosario Santa Fe Argentina

Surfaces and Interfaces Diamond Light Source Harwell Science and Innovation Campus Didcot Oxfordshire OX11 0DE United Kingdom

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