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

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, H-2-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 H-2/CO ratio (1.92-2.10). In the water splitting stage, the H-2 contents over La0.85MnCu0.15O3 and La0.8MnCu0.2O3 began to decrease after the second cycles. However, the H-2 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.

Automated summary

La1-xMnCuxO3 perovskites prepared via sol-gel method showed good oxygen mobility and reactivity in chemical looping steam methane reforming process, with high thermal stability and carbon formation resistance. La0.85MnCu0.15O3 and La0.8MnCu0.2O3 exhibited the best performance in terms of syngas productivity and selectivity.