Adsorption and catalytic decomposition of dimethyl sulphide and dimethyl disulphide on metal films of iron, palladium, nickel, aluminium and copper

Abstract

The interaction of dimethyl sulphide (Me₂S) and dimethyl disulphide (Me₂S₂) has been studied with metal films of Fe, Pd, Ni, Al and Cu over the temperature ranges 193–500 K with Me₂S and 223–600 K in the case of Me₂S₂. At 193 K mainly molecular chemisorption of Me₂S occurred on the films. With Me₂S₂, multilayer adsorption, involving both chemisorption and van der Waals adsorption, took place on the films at 223 K. Dissociative chemisorption of Me₂S or Me₂S₂ began above 300 K and was accompanied by the evolution of gaseous products. The latter involved H₂, CH₄ and C₂H₆ gases with Me₂S and H₂, CH₄, C₂H₆, MeSH and Me₂S subsequent to the dissociation of Me₂S₂. Additional gaseous products throughout the decomposition on the oxidized films were CO, H₂O and C₂H₄. The rate of Me₂S or Me₂S₂ chemisorption depended on the pressure of the reacting gas, and the kinetic data indicated the operation of a compensation effect throughout the interaction of Me₂S or Me₂S₂ with the films. On the basis of kinetic data it was possible to arrange the metal films in the order of decreasing activity toward Me₂S or Me₂S₂ adsorption. The transition-metal films showed greater activity than Al and Cu, and among the former films Fe showed the greatest activity, for chemisorption of Me₂S and Me₂S₂. All the metals have higher tendencies for Me₂S adsorption than for Me₂S₂.