Research On Efficient Adsorbents For Low Concentration CO₂ Capture

CO2 is one of the main greenhouse gases, but the majority of industrial output of CO2 without adequate recovery, which not only accelerate the pace of the greenhouse effect, but also waste a lot of carbon resources. So best utilization of CO2 recycling is important for scientific significance and application value. The purpose of this study is to develop efficient adsorbens for low-concentration CO2 removal from N2 steam using fixed-bed reactor. The contents of the job are listed as follows:1. The investigation of molecular sieve of CO2 adsorption. The adsorption capacity of different types of adsorbents has been investigated. The effect of the gas flow rate, adsorption temperature, bed height and pretreatment on the adsorption breakthrough curve, adsorption capaeity are investigated. Results show that 5A molecular sieve which is molded by aluminum sol binder has the best adsorption properties of CO2. Appropriately increasing bed thickness and low temperature operation are both conducive to the absorption of CO2. But the increased flow rate is not conducive to the absorption of CO2. The CO2 adsorption rate increases while using 5A molecular sieve heated at 300℃for 3h. Pretreatment of nitrogen containing water will cause the pore blockage of 5A molecular sieve which lead to the decrease of CO2 adsorption capacity.2. The study on the modified 5 A molecular sieve of CO2 adsorption.5 A molecular sieve is treated by metal ions modifieation. Some factors which may affect the adsorption capacity such as the species and the concentration of metal salts are also investigated in the fixed-bed reactor. Results show that Cu4+, Mn3+, Cr2+ modification can cause the decline of the CO2 absorption capacity.3. The investigation of the regeneration of 5A molecular sieve. From theTG results, we find that 5A molecular sieves are good adsorbents with high capacity as well as strong bonding with CO2. Results also show that after recycling of 5A molecular sieve for 6 times, its CO2 adsorption capacity does not decrease significantly.5A molecular sieve has effective adsorption performance after heating regeneration for 180min at 300℃.4. The study on CO2 absorption capacity with SBA-15 mesoporous molecular sieve. SBA-15 mesoporous molecular sieve is used as support, then PEI amino modification is investigated. The concentration of PEI as well as modification temperature are studied as the factor of CO2 absorption capacity. XRD and TG results are analyzed. Results show that the best ratio of PEI is wt50%, the optimum temperature is 48℃. Finally, the regeneration of SBA-15-PEI-50 is investigated. Results show that its regeneration condition is simple, SBA-15-PEI-50 can be regenerated at 100℃with N2 flow rate of 100mL/min.