SULFUR POISONING OF BOUDOUARD AND METHANATION REACTIONS ON NICKEL CATALYSTS

The Boudouard and methanation reactions were studied over a nickel catalyst under conditions where both reactions could be followed simultaneously. The dynamics of the reactions during a sulfur poisoning were followed in a thermogravimetric apparatus. During the drastic deactivation, the selectivity was constant, which indicates that the two reactions have the same intermediate. The poisoning of the methanation reaction was further studied on presulfided samples. The effect of sulfur is strongly nonlinear, but the activation energy remains constant. This indicates that the poisoning is geometrical, and that the methanation reaction requires an ensemble with several nickel atoms. © 1979 Academic Press, Inc. All rights reserved.