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Alumina-grafted SBA-15 as a high performance support for Pd-catalysed cinnamyl alcohol selective oxidation

DOI: 10.1016/j.cattod.2013.11.056 DOI Help

Authors: Christopher Parlett (University of Warwick) , Lee Durndell (University of Warwick) , Andreia Machado (University of Warwick) , Giannantonio Cibin (Diamond Light Source) , Duncan W. Bruce (University of York) , Nicole S. Hondow (University of Leeds) , Karen Wilson (Aston University) , Adam F. Lee (Monash University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Catalysis Today

State: Published (Approved)
Published: January 2014
Diamond Proposal Number(s): 7668

Abstract: 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 nanoparticles 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 CO cleavage of the cinnamyl alcohol reactant to trans-β-methylstyrene, and of cinnamaldehyde decarbonylation to styrene.

Journal Keywords: Palladium; Selective Oxidation; Operando; Xas; Alumina; Sba-15.

Subject Areas: Chemistry, Materials

Instruments: B18-Core EXAFS