CO2 adsorption using PEI-impregnated mesoporous silica foam derived from power plant fly ash

초록

A family of highly efficient amine-impregnated silica foams with ultra large mesopores has been reported for global warming CO2 capture. The silica foam can be synthesized using inexpensive sodium silicate under nearly neutral conditions without additive such as 1,3,5-trimethylbenzene, which significantly simplify the scale-up synthesis and reduce cost. Improper disposal of power plant fly ash is a serious burden to the environment and its conversion into useful products has been pursued. In this work, we prepared a porous silica foam using sodium silicate extracted from fly ash. The structure directing agent Pluronic P123 was dissolved in the mixture of acetic acid, de-ionized water and ammonium fluoride at 40 °C for 2 h. Then a solution of extracted sodium silicate in water was added and the mixture was kept at 40 °C for 24 h, followed by aging at 70 °C for 12h. The obtained product was calcined at 560 oC for 6 h to remove the surfactant. Finally, polyethyleneimine (PEI) was introduced into the silica foam by wet impregnation, and tested for CO2 adsorption. CO2 capture capacity, selectivity against N2, and recyclability of the PEI-impregnated adsorbent were also investigated.