CO₂ Adsorption and Catalytic Performance of Porphyrin-Based Porous Organic Polymers

In order to achieve high efficiency in the cycloaddition reaction of CO₂ under the conditions of mild environment and absence of cocatalyst, two kinds of porphyrin-based porous organic polymers (PPOP-COOH and PPOP-I) were designed and synthesized in this paper. The nucleophilic groups and metal active centers of quaternary ammonium salts were introduced into the polymers by means of pre-modification and post-modification. The two crosslinked polymers showed excellent chemical and thermal stability. The chemical structures and pore structures of the two polymers were characterized, and both of them had hierarchical porous structure with specific surface areas of 302—514 m²/g. Under the condition of 298 K, CO₂ adsorption and desorption tests were carried out, and the results showed that CO₂ adsorption capacity of carboxyl-containing polymer was greater than that of quaternary ammonium salt containing polymer. The effect of the catalyst on the cycloaddition reaction of CO₂ was studied. The results showed that the synergistic effect of Lewis acid metal ions, nucleophiles and multi-pore structure greatly promoted the CO₂ cycloaddition reaction. Under moderate conditions (80 ℃, 0.3 MPa, 24 h), the reaction selectivity and conversion were more than 99%, and the polymers still presented good catalytic performances after being reused for many times.