Study on the unsteady state oxidative coupling of methane: effects of oxygen species from O-2, surface lattice oxygen, and CO(2)on the C(2+)selectivity

Abstract

This study examined the effects of oxygen species on the unsteady-state oxidative coupling of methane (OCM) using a lengthy catalyst bed of Na2WO4/Mn/SiO2. The reaction conditions, including the methane-to-oxygen ratio, ratio of feed gas dilution by N-2, quantity of catalyst, and feed flow rate were adjusted for the continuous flow fixed bed reaction system. While the O(2)gas initiated methyl radical formation from methane, the surface lattice oxygen atoms improved the dehydrogenation of paraffins to olefins without significant activation of methane. The addition of CO(2)as a mild oxidizing agent was also tested and slightly improved OCM selectivity with slightly lower methane conversion were observed.