Investigation of CO2 adsorption performance of amine impregnated adsorbents using amine-support matching strategies

Supports and the organic amine type are the main factors affecting the performance of adsorbents. Currently, researchers are focusing on the development of supports, but their high cost limits the applications. In addition, there is a lack of studies on the mechanism of matching organic amines to supports. This paper presents a feasible strategy including the preparation of low-cost mesoporous nano-SiO2 (B-SiO2) support from blast furnace slag (BFS). A series of adsorbents were obtained by impregnating with different organic amines on the B-SiO2 support to identify the most suitable amine type for B-SiO2. The results showed that the matching degree four amines with B-SiO2 was TETA > TEPA > PEHA > PEI in order. TETA at 35 wt.% was the best matched amine for B-SiO2, exhibiting the highest CO2 adsorption capacity of 112.89 mg/g and the best adsorption energy Eads = −87.21 kJ/mol at 80 ℃. This is mainly due to two reasons. On the one hand, TETA is easily dispersed in the pores of the support, which not only effectively prevents the agglomeration effect and improves the accessibility of the active site, but also facilitates the inhibition of amine leaching. On the other hand, TETA has the least steric hindrance and the highest affinity for CO2, thus reducing the mass transfer resistance and improving the adsorption performance. In addition, four adsorption kinetic models were developed. The Avrami model was the best fit for four adsorbents. It indicates that the adsorption mechanism of this type of adsorbent is a combination of physical and chemical adsorption. This study reveals the matching rules between amine species and supports, and provides theoretical guidance for the preparation of solid amine-based adsorbents.