Enhanced activity of La1-xMnCuxO3 perovskite oxides for chemical looping steam methane reforming

Abstract

Chemical looping steam methane reforming (CL-SMR) is a promising pathway for producing syngas and hydrogen. A series of La1-xMnCuxO3 (x = 0, 0.05, 0.1, 0.15, 0.2) perovskites as the oxygen carriers were prepared via sol-gel method. The physicochemical properties of oxygen carriers were determined by XRD, BET, H2-TPR and CH4-TPR. Compared with the pure LaMnO3, La1-xMnCuxO3 oxygen carriers exhibited smaller crystal size and cell volume, and better reducibility. La1-xMnCuxO3 oxygen carriers also exhibited good oxygen mobility and high reactivity during the CL-SMR process. In the methane partial oxidation stage, the syngas productivity of La1-xMnCuxO3 (2.79–5.20 mmol/g) increased gradually with the Cu content. La0.85MnCu0.15O3 and La0.8MnCu0.2O3 showed higher CO selectivity and appropriate H2/CO ratio (1.92–2.10). In the water splitting stage, the H2 contents over La0.85MnCu0.15O3 and La0.8MnCu0.2O3 began to decrease after the second cycles. However, the H2 contents maintained at a relatively stable level during 3–11 cycles, suggesting a thermal stability. There was no CO formed in the water splitting step during 3–11 cycles, indicating better carbon formation resistance.