MgO/Al_2O_3 Sorbent for CO_2 Capture

摘要

The MgO/Al_2O_3 sorbent for CO_2 capture under low temperatures was investigated in a fixed bed. It was found that, with MgO loading of 10 wt %, MgO/Al_2O_3 sorbent showed a maximum CO_2 capture capacity, which originated from the balance of physical adsorption and chemical absorption of the sorbent. The CO_2 capture capacity increased with the water vapor at first and then decreased. Typically, the total CO_2 capture capacities were as high as 0.97 and 1.36 mmol/g, with water vapor concentration of 0 and 13 vol %, respectively, at 60 ℃ with 13 vol % CO_2. The high CO_2 concentration could be approached by the multistage absorption/desorption cycles, during which the sorbent could be regenerated at 350 °C and maintained stable even after 5 cycles. In addition, a deactivation model was proposed that gave good predictions of the CO_2 breakthrough curves. Results showed that sorption rate parameters obtained in the presence of water vapor were found to be larger than the corresponding values in the absence of water vapor. It was possibly caused by increasing the reactivity of the sorbent prior to the sorption of CO_2 in the presence of water vapor.