The effect of copper and gold on the catalytic behavior of nickel/alumina catalysts in hydrogen-assisted dechlorination of 1,2-dichloroethane

Abstract

Two series of alumina-supported Ni–Cu and Ni–Au catalysts were prepared by incipient wetness co-impregnation and characterized using nitrogen adsorption at −196 °C, X-ray diffraction, hydrogen chemisorption, and temperature-programmed reduction methods. The presence of different alloy phases found in reduced Ni–Cu and Ni–Au catalysts was in fair agreement with the phases predicted by the thermodynamics of these systems suggesting that a reasonable extent of alloying was achieved for both alloy systems. The Ni–Cu/Al 2O 3 and Ni–Au/Al 2O 3 catalysts were tested in the reaction of hydrodechlorination of 1,2-dichloroethane at 250 and 270 °C. Adding Cu or Au to Ni/Al 2O 3 introduces substantial, although different, changes in the catalytic behavior, especially in the product selectivity. The presence of copper enhances the propensity of nickel towards vinyl chloride formation (from ∼60% to ∼85%), whereas addition of gold increases the selectivity to ethene (∼20% to ∼60%), at 250 °C. Differences in catalytic behavior of both alloy systems are discussed.