The use of a combined gas chromatograph-mass spectrometer to study the deuterolysis of neopentane over iron films

Abstract

The application of a combined gas chromatograph-mass spectrometer to catalytic reactions is described, particularly with reference to the reactions between deuterium and hydrocarbons over metal films. The analysis was complicated by partial separation of hydrocarbon isotopes in the gas chromatograph and different sensitivities of the equipment to 'light’ and ‘heavy’ methane. For the reaction of neopentane with deuterium over iron films exchange occurs 2.0 times more rapidly than hydrogenolysis and yields (CH 3 ) 3 (CH 2 D)C and (CH 3 ) 3 (CD 3 )C as the only initial deuterated neopentanes. Stepwise exchange occurs at 1.5 times the rate of multiple exchange. The absence of exchange products originating from an αγ -adsorbed intermediate suggests that αγ species are irreversibly adsorbed and lead directly to carbon-carbon bond rupture. The hydrogenolysis gives extensive degradation of neopentane, leading to 99% methane and small quantities of isobutane. The hydrogenolysis products were completely exchanged.