Chemical fixation of carbon dioxide to propylene carbonate over amine-functionalized silica catalysts

Amine-functionalized silica catalysts (NH2/SiO2, NH(CH2)2NH2/SiO2 and 1,5,7-triazabicyclo[4,4,0]dec-5-ene/SiO2 (TBD/SiO2)), which were characterized by 29Si NMR, elemental analysis, N2 adsorption–desorption method and indicator dye adsorption, were prepared by ultrasonic technique under mild conditions. Such hybrid solid bases showed high catalytic activity towards CO2 coupling with epoxide. However, it was found that the reaction conditions had a great influence on the performance. Furthermore, silanols on the surface played an important role in the chemical fixation of CO2. Based on these, the possible reaction mechanism was proposed for CO2 coupling with epoxide over such type of catalysts.