CO hydrogenation on nickel-based catalysts: Effects of copper addition

The effect of copper addition on the catalytic properties of silica-support ed nickel catalysts for the reaction of CO hydrogenation in the temperature range of 200-500 degrees C has been investigated. Different effects, posit ive or negative, depending on the temperature and the copper content, are d escribed and explained. At low temperature (230 degrees C), the addition of a low copper content prevents the loss of the active surface by sintering without inhibiting the rate of CO hydrogenation too much. At high temperatu res (450 degrees C), high copper content is necessary to limit the accumula tion of poisonous carbon products, but at the expense of CO conversion. On the basis of the various kinetic and morphologic effects of copper addition , an advanced description of the CO hydrogenation mechanism is also provide d, assuming an active site formed by 2-3 adjacent Ni atoms, whatever the te mperature or the copper content may be. (C) 2000 Academic Press.