Preparation of mesoporous oxides and their support effects on Pt nanoparticle catalysts in catalytic hydrogenation of furfural

Mesoporous SiO2, Al2O3, TiO2, Nb2O5, and Ta2O5 were synthesized through a soft-templating approach by a self-assembled framework of Pluronic P123 and utilized for the preparation of 3-dimensional catalysts as supports. Colloidal Pt nanoparticles with an average diameter of 1.9 nm were incorporated into the mesoporous oxides by sonication-induced capillary inclusion. The Pt nanoparticles supported on mesoporous oxides were evaluated in the hydrogenation reaction of furfural (70 tort furfural and 700 torr H-2 with a balance of He) to study the effect of catalyst supports on selectivity. In the temperature ranges of 170-240 degrees C, the major products of this reaction were furan, furfuryl alcohol, and 2-methyl furan through a main reaction pathway of either decarbonylation or carbonyl group hydrogenation. While Pt nanoparticles with the size ranges of 1.5-7.1 exhibited strong structure-dependent selectivity, various supports loaded with only 1.9 nm Pt nanoparticles produced dominantly furan as a major product. Compared to the inert silica support, TiO2 and Nb2O5 facilitated an increase in the production of furfuryl alcohol via carbonyl group hydrogenation as a result of a charge transfer interaction between the Pt and the acidic surface of the oxides. The same trend was confirmed on 2-dimensional type catalysts, in which thin films of SiO2, Al2O3, TiO2, Nb2O5, and ZrO2 were prepared as supports. When furfural hydrogenation was conducted (1 torr furfural, 100 torr H-2, and 659 torr He) over Pt nanoparticle monolayers deposited on oxide substrates, only TiO2 was shown to increase the production of furfuryl alcohol, while other oxides produced furan. (c) 2012 Elsevier Inc. All rights reserved.