Effect of Temperature on CO 2 Adsorption onto Amine-Functionalized KIT-6 Adsorbents.

The mesoporous silica KIT-6 was synthesized and functionalized with 3-aminopropyltriethoxysilane (APTES) by grafting at 110 °C. The composites were prepared with three different concentrations of APTES: 20, 30 and 40 wt.%. The as-prepared samples were characterized by thermal gravimetric analysis in air and nitrogen atmosphere (TG/DTA), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction and nitrogen adsorption-desorption. In this study, CO 2 adsorption-desorption was investigated using temperature programmed desorption mass spectrometry (TPD-MS) at different temperatures. The adsorption capacity of the prepared composites is 2.23 mmol CO 2 /g at 40 °C and decreases to 0.95 mmol/g at 70 °C. Regarding the efficiency of the amino groups, the best result was obtained for APTES-grafted KIT-6 at 40 °C, with 0.512 mmol CO 2 /mmol NH 2 . The results showed good cyclical stability in adsorption capacities even after nine adsorption-desorption cycles.