Assessment on Effect of Molar Ratio of Inflow Gas on Characteristics of Biogas Dry Reforming

Abstract

To improve the H2 yield and thermal efficiency for the biogas dry reforming process, this study has been conducted the experimental investigation using a membrane reactor by changing reaction temperature, differential pressure between reaction chamber and sweep chamber, and molar ratio of inflow gas with and without a sweep gas. In particular, we have focused on the effect of molar ratio of inflow gas. The concentrations of reactant and product gases were measured by gas chromatography to clarify the effects of the above operation conditions on the reaction characteristics. We have evaluated the conversion of the reacted gases (CH4 and CO2), H2 yield, H2 permeability, and thermal efficiency. As a result, the largest H2 was produced at the molar ratio of 1.5:1 irrespective of reaction temperature, and the differential pressure between reaction chamber and sweep chamber with and without a sweep gas. It was observed that the concentration of CO is larger than that of H2 irrespective of reaction temperature, differential pressure between reaction chamber and sweep chamber, and molar ratio of inflow gas with and without a sweep gas. Under the experimental conditions in this study, the H2 separation rate which is enhanced by the differential pressure and sweep gas exceeded the kinetic rate of H2 production, resulting in a low concentration of produced H2. Therefore, it is necessary to clarify the optimum conditions where the H2 separation rate matches the kinetic rate of H2 production.