Hierarchically Ordered Nanoporous Pd/SBA-15 Catalyst for the Aerobic Selective Oxidation of Sterically Challenging Allylic Alcohols

• Published in: ACS catalysis Vol. 3; no. 9; pp. 2122 - 2129
• Main Authors: Parlett, Christopher M. A, Keshwalla, Pooja, Wainwright, Stephen G, Bruce, Duncan W, Hondow, Nicole S, Wilson, Karen, Lee, Adam F
• Format: Journal Article
• Language: English
• Published: American Chemical Society 06-09-2013
• Subjects: alcohol; macroporous; selective oxidation; hierarchical; palladium; SBA-15; mesoporous
• ISSN: 2155-5435; 2155-5435
• DOI: 10.1021/cs400371a

The utility of a hierarchically ordered nanoporous SBA-15 architecture, comprising 270 nm macropores and 5 nm mesopores (MM-SBA-15), for the catalytic aerobic selective oxidation of sterically challenging allylic alcohols is shown. Detailed bulk and surface characterization reveals that incorporation of complementary macropores into mesoporous SBA-15 enhances the dispersion of sub 2 nm Pd nanoparticles and thus their degree of surface oxidation. Kinetic profiling reveals a relationship between nanoparticle dispersion and oxidation rate, identifying surface PdO as the catalytically active phase. Hierarchical nanoporous Pd/MM-SBA-15 outperforms mesoporous analogues in allylic alcohol selective oxidation by (i) stabilizing PdO nanoparticles and (ii) dramatically improving in-pore diffusion and access to active sites by sesquiterpenoid substrates such as farnesol and phytol.