K2CO3 promoted novel Li4SiO4-based sorbents from sepiolite with high CO2 capture capacity under different CO2 partial pressures

摘要

CO2 sorption at high temperature is recently attracting increasing attention. In the study, lithium silicate (Li4SiO4) based sorbents were synthesized using sepiolite as silicon source. The effect of the purity, crystallite size, and specific surface area of Li4SiO4 synthesized by different methods on the CO2 sorption performance were studied systematically. Moreover, the CO2 uptake of Li4SiO4 sorbents was improved by using K2CO3. The relationship between the CO2 uptake performance and doping amount of K2CO3 under different CO2 partial pressure was investigated in detail. Results show that the doping amount of K2CO3 was 17.5 wt%, 12.5 wt% and 15 wt%, the CO2 sorption value of synthesized Li4SiO4 samples was 27.67 wt%, 30.69 wt%, 32.95 wt%, respectively. Meanwhile, the K2CO3 promoted mechanism was discussed. Finally, the sorption/desorption cycles were performed under pressure swing sorption (PSA) and temperature swing sorption (TSA) procedures, which displayed high cycling stability after 22 cycles.