期刊
CATALYSIS TODAY
卷 229, 期 -, 页码 46-55出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.cattod.2013.11.056
关键词
Palladium; Selective oxidation; Operando; XAS; Alumina; SBA-15
资金
- EPSRC [EP/E046754/1, EP/G007594/2, EP/F009488/1]
- Leadership Fellowship
- Diamond Light Source for beamtime [SP7668-1]
- Royal Society
- EPSRC [EP/F009488/1, EP/G007594/2, EP/G007594/3, EP/E046754/1, EP/K023853/1] Funding Source: UKRI
- Engineering and Physical Sciences Research Council [EP/G007594/3, EP/G007594/2, EP/E046754/1, EP/K023853/1, EP/F009488/1, EP/J021156/1] Funding Source: researchfish
Ultrathin alumina monolayers grafted onto an ordered mesoporous SBA-15 silica framework afford a composite catalyst support with unique structural properties and surface chemistry. Palladium nanopartides deposited onto Al-SBA-15 via wet impregnation exhibit the high dispersion and surface oxidation characteristic of pure aluminas, in conjunction with the high active site densities characteristic of thermally stable, high-area mesoporous silicas. This combination confers significant rate enhancements in the aerobic selective oxidation (selox) of cinnamyl alcohol over Pd/Al-SBA-15 compared to mesoporous alumina or silica supports. Operando, liquid-phase XAS highlights the interplay between dissolved oxygen and the oxidation state of palladium nanoparticles dispersed over Al-SBA-15 towards on-stream reduction: ambient pressures of flowing oxygen are sufficient to hinder palladium oxide reduction to metal, enabling a high selox activity to be maintained, whereas rapid PdO reduction and concomitant catalyst deactivation occurs under static oxygen. Selectivity to the desired cinnamaldehyde product mirrors these trends in activity, with flowing oxygen minimising C-O cleavage of the cinnamyl alcohol reactant to trans-beta-methylstyrene, and of cinnamaldehyde decarbonylation to styrene. (C) 2013 Elsevier B.V. All rights reserved.
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