title: The preparation of large surface area lanthanum based perovskite supports for AuPt nanoparticles: tuning the glycerol oxidation reaction pathway by switching the perovskite B site.
abstract: Gold and gold alloys, in the form of supported nanoparticles, have been shown over the last three decades to be highly effective oxidation catalysts. Mixed metal oxide perovskites, with their high structural tolerance, are ideal for investigating how changes in the chemical composition of supports affect the catalysts' properties, while retaining similar surface areas, morphologies and metal co-ordinations. However, a significant disadvantage of using perovskites as supports is their high crystallinity and small surface area. We report the use of a supercritical carbon dioxide anti-solvent precipitation methodology to prepare large surface area lanthanum based perovskites, making the deposition of 1 wt% AuPt nanoparticles feasible. These catalysts were used for the selective oxidation of glycerol. By changing the elemental composition of the perovskite B site, we dramatically altered the reaction pathway between a sequential oxidation route to glyceric or tartronic acid and a dehydration reaction pathway to lactic acid. Selectivity profiles were correlated to reported oxygen adsorption capacities of the perovskite supports and also to changes in the AuPt nanoparticle morphologies. Extended time on line analysis using the best oxidation catalyst (AuPt/LaMnO3) produced an exceptionally high tartronic acid yield. LaMnO3 produced from alternative preparation methods was found to have lower activities, but gave comparable selectivity profiles to that produced using the supercritical carbon dioxide anti-solvent precipitation methodology.
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, UK. kondratsa@cardiff.ac.uk.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Evans
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, UK. kondratsa@cardiff.ac.uk.
authors.forename: Simon A
authors.initials: SA
authors.lastname: Kondrat
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, UK. kondratsa@cardiff.ac.uk.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Smith
authors.affiliation: Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK.
authors.forename: Troy D
authors.initials: TD
authors.lastname: Manning
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, UK. kondratsa@cardiff.ac.uk.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Miedziak
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, UK. kondratsa@cardiff.ac.uk.
authors.forename: Gemma L
authors.initials: GL
authors.lastname: Brett
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, UK. kondratsa@cardiff.ac.uk.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Armstrong
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, UK. kondratsa@cardiff.ac.uk.
authors.forename: Jonathan K
authors.initials: JK
authors.lastname: Bartley
authors.affiliation: Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, UK. kondratsa@cardiff.ac.uk.
authors.forename: Stuart H
authors.initials: SH
authors.lastname: Taylor
authors.affiliation: Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Rosseinsky
authors.affiliation: Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK.
authors.forename: Graham J
authors.initials: GJ
authors.lastname: Hutchings