The effect of post-processing conditions on aminosilane functionalizaiton of mesocellular silica foam for post-combustion CO_2 capture

摘要

The objective of this research is to develop amine-grafted mesocellular silica foams (MCFs) based CO_2 sorbents. The template of the as-synthesized MCFs was removed by calcination or ethanol extraction method. The obtained template-free MCFs were grafted with 3-aminopropyltriethoxysilane (APS) or 3-(2-aminoethylamino)-propyl-dimethoxymethylsilane (APMS). These new composite sorbents were characterized by nitrogen adsorption/desorption, Fourier transform infrared spectroscopy (FTIR), and thermal gravimetric analysis (TGA). The infrared results indicate that more silanol groups were preserved on solvent-extracted MCF than that on calcined MCF. CO_2 capture performances of the sorbents were evaluated using a fixed-bed reactor equipped with an online mass spectrometer (MS). Experimental results show that the solvent-extracted MCF grafted with APMS exhibited a higher CO_2 adsorption capacity (1.54 mmol/g) under the condition of 10.0% (v/v) CO_2 in N_2 at 60 ℃. It was also found that the APMS-grafted sorbents are more capable in CO_2 sorption than APS-grafted ones possibly due to the higher amine content of the formers, and the CO_2 uptake can be further enhanced to 2.02 mmol/g in the presence of moisture. Cyclic CO_2 adsorption-desorption test results indicate that the composite sorbents are stable and regenerable.