Study on deuterium exchange in surface CHx species formed from methane over platinum, ruthenium and cobalt under non-oxidative conditions

Abstract

Dissociative chemisorption of methane over ruthenium, cobalt, platinum and their bimetallic counterparts supported by alumina and NaY was investigated under a wide range of temperatures. The extent of hydrogen loss from methane was monitored by deuterium uptake of the surface CHx species formed from methane during the course of methane chemisorption. The presence of a high average number of deuterium in the desorbing methane suggested a widespread dissociation of methane. The initial distribution of the deuterated products generally decreased in the sequence CD4>CHD3>CH2D2. The amount of chemisorbed methane during methane chemisorption increases with temperature and it follows the sequence of reducibility of the supported metals and particle size which, in turn, depends on the support and the alloy formed. CHx (x=1) species prevailed on alumina supported catalysts, while on NaY supported metals, CH2 species are dominant when small metal particles are stabilized inside the supercage.