Kinetic Analysis of Dry Reforming of Methane on Traditional and Membrane Catalysts

Abstract

The article presents an analysis of the kinetic data on dry reforming of methane (DRM) in reactors with traditional (TC) and membrane catalysts (MC). The kinetic experiment in reactors with the TC and MC is performed in the temperature range of 820–900°С at CH₄ : CO₂ = 1 : 1. The experiment reveals intensification of the reaction of methane cracking; its rate constant increases by an order of magnitude. This difference in the DRM data obtained for the studied catalysts is explained by the fact in the case of the MC mass transfer is intensified due to the thermal slip phenomenon. A mathematical description corresponding to the kinetic scheme of the DRM process is proposed, and the rate constants of direct and reverse reactions in both reactors are determined. The DRM process carried out on the TC yields water vapor, while in the case of the MC syngas is produced. On the TC the DRM process is accompanied by the accumulation of carbon deposits (CDs), while on the MC this accumulation is absent. On the TC the DRM process is characterized by three main reactions (methane cracking, gasification of CDs with carbon dioxide and/or water vapor, and reverse water gas shift) which are assumed to be reversible under the experimental conditions. It is found that the gasification of CDs on the TC occurs in the reverse reaction of methane cracking; on the MC, in the reactions of CDs gasification with water vapor (mostly) and carbon dioxide. In the case of the MC, the process is characterized by the irreversible reactions of methane cracking and CDs gasification with water vapor and carbon dioxide. The reverse water gas shift reaction on the MC remains reversible, and its rate constants of direct and reverse reactions are an order of magnitude lower than similar rate constants on the TC.