Adsorption of neopentane on tungsten and palladium films

Abstract

The adsorption of neopentane has been studied on tungsten and on palladium films; allied experiments were carried out with methane (W, Pd) and with propane (W). The evolution of hydrogen from each gas/metal system was studied as a function of time and temperature; reaction with gas phase deuterium was used to determine how many of the hydrogen atoms in the surface phase were exchangeable, either rapidly or by slower processes.

Rapid dissociative chemisorption, involving the cleavage of an average of 3 or 4 C—H bonds occurred with neopentane or propane on tungsten. Neopentane was chemisorbed on palladium at room temperature but dissociation of methane was not observed below ∼373 K; the extent of the dissociation of both hydrocarbons was smaller than on tungsten. Further breakdown of the surface species, accompanied by evolution of hydrogen, occurred with all systems on raising the temperature. Evidence for C—C bond rupture was obtained from the hydrogenolysis of neopentane at higher temperatures.