Hydroxyl-Based Hyper-Cross-Linked Microporous Polymers and Their Excellent Performance for CO ₂ Capture

A series of benzyl alcohol (BA)-based hyper-cross-linked microporous polymers (HCPs) were designed and synthesized via facile Friedel-Crafts alkylation using formaldehyde dimethyl acetal (FDA) as external cross-linker promoted by anhydrous ferric chloride (FeCl ₃ ). Results demonstrated that Brunauer-Emmett-Teller (BET) specific surface area and pore volume for the HCPs could be controlled by adjusting the amount of FDA and FeCl ₃ . The HCPs obtained under optimal conditions showed a BET specific surface area up to 1101 m ² /g, whose capacity of CO ₂ uptake could be as high as 3.03 mmol/g at 273 K/1.0 bar. The isosteric heats of CO ₂ sorption for the BA-based HCPs exceed 27 kJ/mol at the low coverage. In addition, the polymer networks possessed high CO ₂ /N ₂ selectivity of 42. Compared with those BA-based HCPs which is without FDA, the prepared material has higher BET specific surface area and superior CO ₂ adsorption properties. These results demonstrated that these prepared HCPs are promising for CO ₂ capture and sequestration.