The formation of metal-alumina-rhenium methane dehydrocyclohexamerization catalysts during the reactant-catalyst interaction

Abstract

The effect of reactant-catalyst (R-C) interaction on the activation and deactivation of a 0.5 Ni, 1.0 ReOx/Al2O3 catalyst during the dehydrocyclohexamerization of methane to benzene has been studied. The R-C interaction involves partial reduction of the catalyst and the buildup of at least two forms of carbon deposit. It has been found that the catalyst activation time shortens with an increase in the amount of carbon deposit remaining after treatment with air. A comparison of the initial (3 min) and maximal (20 min of experimental run) benzene formation rates with the quantity of carbon deposit remaining on the catalyst after air treatment has shown that the carbon deposit is responsible for the subsequent oligomerization and dehydrocyclization functions of the C2Hy intermediates produced owing to oxygen bonded to the catalyst. It has been suggested that the catalyst deactivation during the reaction is associated with a decrease in the concentration of bound oxygen.