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

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 degrees 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(2)O(3) and Ni-Au/Al(2)O(3) catalysts were tested in the reaction of hydrodechlorination of 1,2-dichloroethane at 250 and 270 degrees C. Adding Cu or Au to Ni/Al(2)O(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 similar to 60% to similar to 85%), whereas addition of gold increases the selectivity to ethene (similar to 20% to similar to 60%), at 250 degrees C. Differences in catalytic behavior of both alloy systems are discussed. (C) 2010 Elsevier B.V. All rights reserved.