Highly Dispersed Silica-Supported Copper Nanoparticles Prepared by Precipitation-Gel Method: A Simple but Efficient and Stable Catalyst for Glycerol Hydrogenolysis

摘要

Highly dispersed copper nanoparticles supported on silica were successfully prepared by a simple and convenient precipitation—gel technique, and their physicochemical properties and activity were compared to those of a catalyst prepared by the conventional impregnation method. As a consequence of the preparation method, the texture (BET), dispersion (dissociative N2O adsorption), morphology (TEM), reduction behavior (TPR, XRD), state of copper species (XPS), and catalytic performance (glycerol hydrogenolysis) differ between samples. Both samples showed high selectivity (>98%) toward 1,2-propanediol in glycerol reaction. Because of a much smaller particle size, a higher dispersion of copper species with a strong metal—support interaction, and more resistance to sintering, the CuO/SiO2 catalyst prepared by precipitation-gel method presented a much higher activity and remarkably better long-term stability in glycerol reaction than did the catalyst prepared by impregnation method. The catalytic behavior of calcined and reduced samples and the structure changes of these samples after reaction allow the understanding of the stability toward sintering as well as the possible mechanism of the reaction.