Synthesis and characterization of Benzyl chloride-based hypercrosslinked polymers and its amine-modification as an adsorbent for CO2 capture

As one of the microporous polymers with nano-sized holes, HCPs have attracted much attention in CO2 capture for a variety of reasons such as their low density, high chemical and physical stability and high specific surface area. On the other hand, amine-modification of the adsorbent is known to improve it. Therefore, research on amine-functionalization of adsorbent HCPs is on the rise. The aim of this study was to synthesize benzyl chloride-based hypercrosslinked adsorbent (B-Cl) using the Friedel–Crafts reaction for CO2 adsorption. In addition, it was modified by post-synthesis modification using low-cost wet impregnation process with an amine to improve its adsorption capacity. Post-synthetically functionalized amination was performed using ethylenediamine (EDA) in the presence of water (B-Cl-1) and methanol (B-Cl-2). Structural properties of the adsorbent were depicted by various spectroscopic techniques. A higher specific surface area was reported for B-Cl (1248.87 m2.g−1) compared to the amine-modified samples (B-Cl-1 (1115.08 m2.g−1) and B-Cl-2 (409.49 m2.g−1)). The CO2 adsorption capacity of benzyl chloride-based hypercrosslinked (B-Cl) and amine-modified samples (B-Cl-1 and B-Cl-2) was evaluated in the different conditions. B-Cl adsorption capacity at (1 bar, 273 K) is 75.14 mg.g−1, which is higher than the amine-modified samples B-Cl-1 (39.15 mg.g−1) and B-Cl-2 (19.10 mg.g−1). On the other hand, the adsorption capacity of amine-modified adsorbent in the presence of accessible and low-cost water solvent (B-Cl-1) at temperatures above 45 ºC increased compared to the unmodified adsorbent. In order to better understand the absorption process, experiments were conducted to investigate isotherm, kinetic, and thermodynamic of the process.