CaO/MgO modified perovskite type oxides for chemical-looping steam reforming of methane

Abstract

Chemical-looping steam methane reforming (CL-SMR) is a novel method proposed on the base of chemical looping combustion (CLC) technology. In the CL-SMR scheme, methane is partially oxidized to syngas (H2/CO=2.0) by the lattice oxygen in reformer reactor in the absence of gaseous oxidant, and then the reduced oxygen carrier is oxidized by steam to produce hydrogen in steam reactor. The use of perovskite type oxide LaFeO3 as an oxygen carrier in CL-SMR was studied. While the basicity of CaO/MgO modified oxygen carriers, LaFeO3-CaO and LaFeO3-MgO, were also synthesized aiming to increase specific surface area, thermostability, and resistance to coke formation. The synthesized oxides were characterized by X-ray diffraction (XRD), H2-temperature-programmed reduction (H2-TPR), Brunauer-Emmett-Teller (BET) surface area and X-ray photoelectron spectroscopy (XPS). Three oxygen carriers exhibited high active and selective for syngas production from methane, and maintained perovskite type over cyclic redox operations. The LF-CaO sample is the best candidate for the CL-SMR of the three samples judging from the reactivity, selectivity, and resistance to carbon formation. It showed good regenerability during 5 redox reactions.