Preparation and characterization of Au-In/APTMS-SBA-15 catalysts for chemoselective hydrogenation of crotonaldehyde to crotyl alcohol

Mesoporous siliceous SBA-15 functionalized by gamma-aminopropyltrimethoxysilane (APTMS) was used to immobilize Au and Au-In nanoparticles via the amino groups. The uniformly sized Au and Au-In spherical particles of around 2 nm were homogeneously dispersed on the mesopore walls of SBA-15. In liquid phase hydrogenation of crotonaldehyde to crotyl alcohol, on the optimal Au5.0In0.75/APTMS-SBA-15 catalyst, the initial selectivity amounts to 78%, and the maximum yield reaches 71%. The high selectivity originates from the suppression of the hydrogenation of the C=O bond being lower than that of the C=C bond after the incorporation of In. Furthermore, the catalyst can be conveniently recovered for reuse without losing its selectivity. In light of a series of spectroscopic studies, the superior catalytic performance of the Au5.0In0.75/APTMS-SBA-15 catalyst is tentatively attributed to the electron-donating effects of APTMS and In alloying with Au, favoring more the binding and hydrogenation of the C=O bond in crotonaldehyde. (C) 2009 Elsevier B.V. All rights reserved.