Aqueous Au-Pd colloids catalyze selective CH4 oxidation to CH3OH with O2 under mild conditions

Aqueous Au-Pd colloids catalyze selective CH₄ oxidation to CH₃OH with O₂ under mild conditions

Nishtha Agarwal¹,Simon J. Freakley¹,Rebecca U. McVicker¹,Sultan M. Althahban²,Nikolaos Dimitratos¹,Qian He¹,David J. Morgan¹,Robert L. Jenkins¹David J. Willock¹,Stuart H. Taylor¹,Christopher J. Kiely¹,²Graham J. Hutchings¹,

1Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, UK.²Department of Materials Science and Engineering, Lehigh University, 5 East Packer Avenue, Bethlehem, PA 18015, USA.

http://science.sciencemag.org/content/early/2017/09/06/science.aan6515

Abstract

The selective oxidation of methane, the primary component of natural gas, remains an important challenge in catalysis. Using colloidal gold-palladium nanoparticles rather than the same nanoparticles supported on titanium oxide, we oxidized methane to methanol with high selectivity (92%) in aqueous solution at mild temperatures. Using isotopically labeled O₂ as an oxidant in the presence of H₂O_2, we demonstrate that the methanol produced incorporated a substantial fraction (70%) of gas-phase O₂. More oxygenated products were formed than H₂O₂ consumed, suggesting that the controlled breakdown of H₂O₂ activates methane which subsequently incorporates molecular oxygen through a radical process. If a source of methyl radicals can be established, then the selective oxidation of methane to methanol using molecular oxygen is possible.