Chemical looping oxidative steam reforming of methanol: A new pathway for auto-thermal conversion

Abstract

Auto-thermal reforming of methanol is an attractive route for low-temperature methanol conversion for hydrogen production. This paper describes utilization the lattice oxygen of Cu2O/Ca2Fe2O5 participates the partial oxidation of methanol to achieve the efficient auto-thermal reforming of methanol. ASPEN Plus software was adopted to verify the feasibility of auto-thermal conversion of methanol via Cu↔Cu2O looping and provided a comprehensive understanding of the associated process via operating parameter optimization. A series of CuO/Ca2Fe2O5 with different contents of copper were prepared as the catalytic oxygen carrier (COC) which goes through the reduction → catalytic methanol conversion →re-oxidation. The surface and bulk properties of COCs were characterized by XRD, XPS, TEM-EDS mapping, Raman, and H2-TPR; the reaction pathways were investigated using CH3OH-pulse and in situ DRIFTS. Results indicate that 40 % Cu-loaded Cu2O-Ca2Fe2O5 shows the highest catalytic activity of the synthesized COCs, and the presence of Ca2Fe2O5 tunes the redox activity and mobility of the lattice oxygen, obtaining a H2 production rate of 37.6 μmol·H2∙g−1·COC·s−1 at 240 °C. The reaction pathways of chemical looping methanol conversion follow the sequence: CH3OH full oxidation → formaldehyde intermediate → methyl-formate intermediate as the amount of lattice oxygen decreases gradually.