Amine functionalized adsorbents have been considered adequate for low temperature CO2 adsorption process because of their high CO2 adsorption capacity and selectivity. A large number of amine functionalized adsorbents had been developed and chemical grafting or physical impregnation was their main approach. Recently, the double-functionalized amine adsorbents fabricated by grafting aminosilanes on solid supports followed by impregnating amines were developed to compensate the low CO2 adsorption capacity of amine-grafted adsorbents. Although they showed good adsorption properties including high amine efficiency, but exhibited low thermal stability in regeneration arising from the leaching of impregnated amine.
In this work, the double-functionalized amine adsorbents with chemical linker were fabricated to improve the performance in regeneration. Chemical linkers having the reactivity with amines were introduced into bare silica support and aminosilane-grafted solid adsorbents, respectively. The covalent bond between the linkers and the amines is expected to improve both the thermal stability by holding amines and the regeneration rate by lowering CO2 binding energy of the amines.
As-prepared adsorbent showed more stable cyclic adsorption capacity and faster adsorption/regeneration rate compared to the double-functionalized amine adsorbents without chemical linker from the thermogravimetric anlysis (TGA). The improvement in the thermal stability was also observed from that results. The chemical bond between the chemical linkers and the amines is confirmed from IR spectra analysis. Adsorption/desorption cyclic testing was performed to assess the long term stability of the fabricated sorbent in the flue gas condition for potential application.