Amine-bifunctionalized ZSM-5/SBA-16 composite for CO2 adsorption

An amine-modified ZSM-5/SBA-16 (ZS) micro-/mesoporous composite was synthesized for CO2 capture using nonionic tri-block copolymer pluronic (F127) as a template, tetraethyl orthosilicate (TEOS) as a silicon source and ZSM-5 zeolite as part of silicon aluminum source by embedding method. The amine-bifunctionalized samples were prepared by first grafting with aminepropyltriethoxysilane (APTES) and then impregnating with different concentrations of tetraethylenepentamine (TEPA). The amine efficiency, adsorption kinetics, thermal stability, regeneration performance and the effects of impregnated amine loadings (30–60%) and temperatures (30–90 °C) on the CO2 adsorption performance were investigated using a thermal gravimetric analyzer (TGA) in the mixed gases (15 vol% CO2 and the balance of N2). The best adsorbent after modification of ZSM-5/SBA-16 composite material was screened to study CO2 adsorption mechanism and adsorption kinetics. With the increase of the TEPA amount, the adsorption capacity of amine-bifunctionalized material first increased and then decreased. At 90 °C, the bifunctionalized ZSM-5/SBA-16 displayed the highest CO2 adsorption performance of 1.630 mmol/g at the TEPA loading of 55%. The CO2 adsorption mechanism of the bifunctionalized material was the synergistic effect of physical adsorption and chemical adsorption. After five adsorption/desorption cycle regenerations, the saturated adsorption capacity of the composite material was 1.496 mmol/g, which was only 8.2% lower than the original adsorption capacity. The composites exhibited good CO2 adsorption performance, indicating the promising industrial applications for CO2 capture form actual flue gas after desulfurization.