Research On Adsorption Of CO₂by DBU-based Sorbents In Fluidized Bed

The excessive emissions of CO2lead to global warming, which has drawn widespread attention around the world. With the advantages of simple device, low consumption of power and easy to automatically control, adsorption has wide application prospects in the field of CO2capture. In this paper,1,8-diazabicyclo[5,4,0]undec-7-ene (DBU) was prepared by impregnation with the carrier of activated carbon. Furthermore, adsorption properties were investigated by the method of atmospheric fluidized bed. Main conclusions are as follows:To applied the Euler model to research fluidized bed particles flow. The results showed that when the superficial gas velocity is0.034m/s, the particle diameter of0.015cm, the particle bulk density of600kg/m3and1000kg/m3, can achieve a better fluidization. The fluidized result of the particle with bulk density of600kg/m3is better than the particle with bulk density of1000kg/m3. The particle bulk density of1000kg/m3for the fluidizing air bubbles can be clearly observed.The results of preparation and characterization of DBU-based Sorbents showed that, activated carbon and activated alumina can payload DBU, and the higher solution concentration of DBU, the higher load rate of DBU. The specific surface area and pore volume of the adsorbents were significantly reduced with the loading ratio of DBU increased, and the average pore size increased. The closure effect of activated alumina from DBU was less than the activated carbon. Morphology of activated carbon was observed before and after the load DBU with scanning electron microscopy, the result was coincide with nitrogen adsorption-desorption test. The thermal gravimetric analysis showed that, DBU can suppress surface water evaporation of the carrier, below140℃adsorbents has a good thermal stability.Adsorption of CO2by DBU-based Sorbents in Fluidized Bed:The amount of activated carbon load of DBU, its CO2adsorption performance improved significantly, DBU load rate of2.3%of the adsorbents for adsorption of CO2to penetrate the largest of34.25mg/g. The adsorbents had an optimal performance to capture CO2when the concentration of CO2and water vapor volume fraction ratio of1:1. Appropriate increase in bed height can effectively improve the performance of the adsorption of CO2. However, the excessive bed height caused the adsorption of large water vapor onto adsorbents underlying, thus, the adsorption ability of upper adsorbents decreased significantly due to the lack of moisture. The desorption process was carried out at80℃of DBU-based Sorbents, the adsorption properties of CO2were substantially unchanged after reusing six times, indicated that the adsorbents were renewable and valuable.The results of the sorbents optimized design showed that, the activated carbon as a carrier, the ethanol as impregnation solution, at the temperature of80℃, prepared DBU-based Sorbents under high pressure, the CO2adsorption capacity reached42.21mg/g. Modified activated carbon with H2O2, HNO3to prepare DBU-based Sorbents, CO2adsorption performance can’t be improved.