Co-processing CH4 and oxygenates on Mo/H-ZSM-5: 2. CH4–CO2 and CH4–HCOOH mixtures

Abstract

Co-processing of formic acid or carbon dioxide with CH₄ (FA/CH₄ = 0.01–0.03 and CO₂/CH₄ = 0.01–0.03) on Mo/H-ZSM-5 catalysts at 950 K with the prospect of kinetically coupling dehydrogenation and deoxygenation cycles results instead in a two-zone, staged bed reactor configuration consisting of upstream oxygenate/CH₄ reforming and downstream CH₄ dehydroaromatization. The addition of an oxygenate co-feed (oxygenate/CH₄ = 0.01–0.03) causes oxidation of the active molybdenum carbide catalyst while producing CO and H₂ until completely converted. Forward rates of C₆H₆ synthesis are unaffected by the introduction of an oxygenate co-feed after rigorously accounting for the thermodynamic reversibility caused by the H₂ produced in oxygenate reforming reactions and the fraction of the active catalyst deemed unavailable for CH₄ DHA. All effects of co-processing oxygenates with CH₄ can be construed in terms of an approach to equilibrium.