Correlations between the auto-combustion of the oxygen carrier precursors and the synthesized oxygen-carrier performances in chemical looping combustion of CH4

CuO-based oxygen carriers (OCs) have a high reactivity and oxygen transport capacity. In this study, the CuO@TiO2-Al2O3 oxygen carrier was prepared by sol-gel combustion synthesis. The effects of the molar ratio of urea-to-copper nitrate trihydrate (the ratio is abbreviated as FER) on the combustion flame, temperature, and gas products during the OC precursor combustion were investigated. And the CH4-fueled chemical looping combustion (CLC) was performed. The precursor combusted rapidly but incompletely with CO2, CO, CH4, and H2 being released; and the combustion temperature increased and then decreased (ranging from 313 degrees C to 570 degrees C), reaching the maximum at FER 0.91 where the intense combustion was rapid within 2.029 s and with simultaneous O2 exhaustion. Moreover, the average CO2 selectivity, CH4 conversion rate, CO2 generation rate, and stability of the OCs during the CLC displayed a negative correlation with the combustion temperature of precursors, and all parameters reached their minimums at FER 0.91.