CO2 capture using in-situ polymerized amines into pore-expanded-SBA-15: Performance evaluation, kinetics, and adsorption isotherms

Over the last decades, carbon dioxide capture has attracted lots of attention and different solution have been proposed, yet the global CO2 concentration is still increasing along with its environmental impacts. Covalently tethered amines were in-situ polymerized into mesoporous silica support, namely PE-SBA-15, for the reversible temperature swing CO2 adsorption. The in-situ polymerization approach shows high loadings of amines in comparison to the grafting technique which was confirmed via thermal decomposition and CHN elemental analysis. The covalent tethering of amines, evidenced by the characteristic absorption peaks via FTIR, resulted in good thermal stability of the sorbent and constant CO2 uptake during multicycle operation. Porosimetry analysis, pore volume and BET surface area, showed a noticeable decrease upon the functionalization of support indicating that most of the pores of the support are occupied by the amines. CO2 capture of the sorbent at different con-centrations and temperatures, from 400 ppm for the direct air CO2 capture to 15 % CO2 for coal-powered plants showed good performance. A reduction in CO2 uptake was noticed upon the decrease in adsorption temperature with an optimum temperature of 25 degrees C. Adsorption kinetics were found to be best represented by a pseudo -second order model with significant adsorption rates. Dry adsorption isotherms of CO2 and N2 were studied at different temperatures and the CO2 isotherms were found to follow Langmuir dual site (LDS) model with a very high selectivity towards CO2. This study shows that in-situ polymerization is a key route for mitigating the continuous increase in atmospheric CO2 concentration.

Automated summary

Carbon dioxide capture has been a topic of interest in recent decades, with various proposed solutions. However, the global CO2 concentration continues to rise, leading to environmental impacts. This study presents an in-situ polymerization approach for CO2 adsorption using covalently tethered amines on a mesoporous silica support. The results show high amine loadings and good thermal stability, with constant CO2 uptake during multiple cycles. The CO2 capture performance of the sorbent was evaluated under different concentrations and temperatures, showing good performance. The study highlights the importance of in-situ polymerization in mitigating the continuous increase in atmospheric CO2 concentration.