Screening loaded perovskite oxygen carriers for chemical looping steam methane reforming

Abstract

Chemical looping steam methane reforming (CL-SMR) is a novel process that produce syngas and hydrogen by using solid oxygen carriers to react with methane. The selection of oxygen carriers is a key problem in the development of CL-SMR. This study screened the perovskites with different A (La, Sr) site elements, different B (Co, Fe) site elements, and different loaded materials (CeO2, ZrO2, Al2O3 and SiO2). The results showed that La in A site presented higher hydrogen production, Fe in B site could help keep the H2/CO ratio of the syngas at about 2, and CeO2 loading could achieve highest H2 purity. Thus, LaFeO3-CeO2 was screened as the optimal oxygen carrier. When WHSV was 11.79 h−1, the CO selectivity of LaFeO3-CeO2 was over 98%, H2/CO ratio of syngas was 2, and H2 purity was about 95%. The sample could recover its original crystalline phases after cyclic reactions. CeO2 could not only provide lattice oxygen for syngas production in POM stage, but also enhance the H2 production in RS stage. Furthermore, although a slight agglomeration of the sample occurred during high temperature reactions, LaFeO3-CeO2 exhibited stable reaction performance during 10 CL-SMR cycles.