A₂B₂-Type Zinc(II) Porphyrin-Modified Organic Polymers with Flexible Linkers for Efficient Fixation of CO₂ to Cyclic Carbonate

Abstract

Two A 2 B 2 -type zinc(II) porphyrin-modified organic polymers Poly(ZnEtPpI 2 /BDDA) and Poly(ZnMePpI 2 /BDDA) were synthesized by the free-radical copolymerization of flexible 1,4-butanediol diacrylate (BDDA) with novel A 2 B 2 -type zinc(II) porphyrins ZnEtPpI 2 and ZnMePpI 2 , respectively. The characterizations of both were carried out successfully. The two organic polymers had abundant dual-function sites (Zn 2+ and I − ) and excellent adsorption capacity for solvent, showing high catalytic activity for the CO 2 fixation to cyclic carbonate under the conditions of 120 °C and 1.0 MPa CO 2 . Specifically, Poly-(ZnEtPpI 2 /BDDA) displayed the highest catalytic activity with a TOF of 1480 h −1 for the cycloaddition of CO 2 and epichlorohydrin (ECH) and wide applicability for different epoxides. Moreover, the Poly(ZnEtPpI 2 /BDDA) showed excellent stability and could be recycled at least 7 times. Finally, the kinetic experiments confirmed that Poly(ZnEtPpI 2 /BDDA) was a promising catalyst with a relatively low activation energy (35.3 kJ/mol) for the fixation of CO 2 to cyclic carbonate.