SBA-15 grafted with 3-aminopropyl triethoxysilane in supercritical propane for CO2 capture

•SC-propane is a more effective solvent than toluene to graft APS onto SBA-15.•The highest CO2 adsorption capacity in grafting occurs at11.0 MPa and 100 °C.•6–49% improvement of CO2 adsorption capacity is found in SC-propane over toluene.•Using SC-propane could greatly reduce the grafting time and well disperse amine

Supercritical propane (SC-propane) was found to be a promising solvent for grafting (3-aminopropyl)triethoxysilane (APS) onto synthesized SBA-15 for CO2 capture. The influence of operating conditions in SC-propane for CO2 adsorption at different pressures (8.3–13.8 MPa), temperatures (85–120 °C), and periods of time (4–16 h) were evaluated. The CO2 adsorption conditions under different partial pressures, temperatures and moisture were evaluated. The results showed a reduction in pore characteristics and an increased amount of grafted APS with increasing pressure and temperature after grafting. After grafting in SC-propane at 11.0 MPa and various temperatures for 16 h, a 3–20% increase in the amount of grafted APS and a 6–49% increase in the CO2 adsorption capacity over the toluene refluxing was observed. The time required for grafting in SC-propane could be reduced while maintaining higher nitrogen content and CO2 adsorption capacity compared with grafting in toluene refluxing.

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