Countercurrent chemical looping for enhanced methane reforming with complete conversion and inherent CO₂ separation

Abstract

Methane reforming is a widely applied chemical process for the production of hydrogen and syngas. It can play an important role in the energy transition, allowing for the production of so called blue hydrogen, or in the processing of biogas for renewable fuel and fertilizer production. This work describes and demonstrates a novel countercurrent chemical looping reforming process, which offers a new mode of reforming with complete conversion of methane, inherent separation of pure CO2, and flexibility in the choice of oxidant allowing for hydrogen or syngas production. The packed-bed chemical-looping reactor operates by storing the favourable oxygen chemical potential inclines of the alternating countercurrent flows using the unique properties of non-stoichiometric oxides. The improvement in chemical equilibrium limitations are illustrated using an analysis of an idealised countercurrent membrane reactor. The concept is experimentally demonstrated in a dry reforming process using the non-stoichiometric oxide CeO2-δ at a temperature of 1203 K. The results show complete oxidation of CH4 to CO2 and H2O in the reduction step, and a cumulative CO2-to-CO molar conversion of 86 % during oxidation.