熔盐改性氧化镁吸附剂制备及固定床低浓度CO2吸附捕集OA北大核心CSTPCD

MgO was prepared through the reaction of magnesium chloride hexahydrate and sodium bicarbonate,which modified by sodium nitrate and sodium carbonate,and granulated into(NaNO3)0.1-MgO particles and(NaNO3)0.1(Na2CO3)0.05-MgO particles(particle size of 1 mm-2 mm).The resulted adsorbent was used for CO2 capture from flue gas.The microstructural changes of the prepared adsorbents before and after CO2 adsorption were characterized by XRD,and thermogravimetric analyzer(TGA)tests were carried out to evaluate the CO2 adsorption/desorption dynamics and cycle stability of the prepared adsorbents.The low-concentration CO2(the concentration of carbon dioxide in the feed gas was in the range of 10%-30%)adsorption performance in a fixed bed with the prepared adsorbents was investigated experimentally.The results show that the molten salt layer of sodium nitrate is formed evenly on the surface of MgO at～300℃to enhance CO2 adsorption.However,there is CO2 diffusion resistance in the molten salt layer,where certain CO2 partial pressure is required as the mass transfer force to push CO2 gas passing through the molten salt layer into the adsorption sites on the MgO surface.Therefore,the recovery efficiency of the low concentration CO2 is reduced obviously in the fixed bed adsorber.It is found that the CO2 partial pressure can be reduced with the addition of sodium carbonate into the molten salt layer,and the low-concentration CO2 capture efficiency can be improved.