Effects of the oxidation state of cerium on the reactivity and sulphur resistance of Ni0/zeolite, Ni0/silica and Ni0/CeO2 catalysts in butane hydrogenolysis
Abstract
Butane hydrogenolysis and resistance to sulphur poisoning have been studied over various ceria-supported nickel catalysts as compared with zeolite and silica–nickel catalysts, with or without cerium additives. In the presence of cerium in exclusively the 3+ oxidation state, the selectivity in favour of methane formation is greatly lowered and the sulphur resistance of the catalysts is weak. This has been attributed to an electron enrichment of the metal due to the presence of Ce3+ ions. When cerium in the 4+ state is present as a CeO2 phase, improved thiotolerance by the catalysts was observed and is ascribed to the oxidative properties of cerium (IV) oxide.