Catalysis by group IB metals. Part 1.—Reaction of buta-1,3-diene with hydrogen and with deuterium catalysed by alumina-supported gold

The reaction of buta-1,3-diene with hydrogen and deuterium has been studied using gold supported on γ-alumina and a mixed boehmite+γ-alumina in the temperature range 443–533 K. The reaction is completely selective for butene formation and, although both catalysts are active for the hydroisomerisation of but-1-ene at 473 K, they do not catalyse the hydrogenation of n-butenes to n-butane. The kinetics and activation energy have been determined together with the variation in product distributions with hydrogen uptake, initial reactant pressures and temperature. The distribution of deuterium in each of the products has been determined and in the reaction with deuterium the products contain an excess of hydrogen over the expected from hydrogen-deuterium mass balance. Buta-1,3-diene is adsorbed on the surface of the gold and subsequently reacts with hydrogen which migrates from the support to the metal. Two types of hydrogen exist on the alumina support. Type A hydrogen equilibrates with gas phase deuterium, whereas type B hydrogen does not react with gas phase deuterium but interacts with adsorbed hydrocarbon. Values for the sizes of the type A and B hydrogen pools are quoted.