Preparation and application of highly dispersed gold nanoparticles supported on silica for catalytic hydrogenation of aromatic nitro compounds

Highly dispersed gold nanoparticles supported on silica were successfully prepared by a novel and simple in situ reduction technique that makes use of the 3-glycidoxypropyl group, -CH2CH2CH2OCH2CHCH2O, on modified silica as reductants. In the new procedure, the organic groups are introduced onto silica via a sol-gel process of tetraethyl orthosilicate (TEOS) and 3-glycidoxypropyl-trimethoxysilane (GPTMS) assisted by ammonia water, with gold nanoparticles uniformly in the range 7.0-9.0 nm. The silica-supported gold nanoparticles were evaluated for the liquid-phase catalyze reduction of various aromatic nitro compounds by molecular hydrogen, and their corresponding amines with high chemoselectivity were obtained under the reaction conditions of 140 degrees C, 4.0 MPa, and 2.5-5 h, particularly for chloronitrobenzenes, the undesirable dechlorination reactions could be avoided completely. (c) 2006 Elsevier Inc. All rights reserved.