Effects of Alkali Metal Oxide Additives on Cu/SiO2 Catalyst in the Dehydrogenation of Ethanol

A series of Cu/SiO 2 catalysts with various alkali metal oxide additives was investigated to elucidate the effects of additives on the catalytic properties of copper catalysts in the dehydrogenation of ethanol. The catalysts were prepared by the impregnation method and were characterized by X-ray diffraction, temperature-programmed reduction, temperature-programmed desorption of CO 2, and H 2 −N 2 O titration. The dehydrogenation reaction was carried out in a continuous-flow reactor at 300 °C under atmospheric pressure. The catalytic properties of the copper catalysts were strongly affected by the additives. The addition of alkali metal oxide increased the concentration of weak basic sites of the catalyst. The increase in turnover frequencies of the alkali-metal-oxide-modified catalysts was mainly due to the promotional effects of weak basic sites on Cu catalysts. KCu/SiO 2 catalyst was very stable in the reaction process. The stabilities of NaCu/SiO 2 and RbCu/SiO 2 catalysts were similar to that of the unmodified catalyst. The decay of the catalysts during reaction was caused by sintering. The kinetics for deactivation can be described by a concentration-independent second-order expression.