Facile synthesis of N-rich porous azo-linked frameworks for selective CO2 capture and conversion

Abstract

Nitrogen-rich molecules such as 3,3′-diaminobenzidine are challenging monomers for the synthesis of N-rich porous azo-linked frameworks (PAFs). In this work, a novel N-rich porous azo-linked framework synthesized from easily available 3,3′-diaminobenzidine at RT was reported. The obtained N-rich porous material showed excellent CO₂ capture capacity (18.2 wt%) and CO₂/N₂ selectivity (45 at 273 K and 42 at 298 K). The N-rich porous material with azo groups at the 3,4-position of the benzene ring provides strong coordination sites for metal catalysts. The azo polymer supported ZnBr₂ catalyst showed higher activities for the conversion of pure CO₂ or a mixture of gases (V_CO2 : V_N2 = 15 : 85) into various cyclic carbonates than homogeneous catalysts under mild conditions, which demonstrated a synergistic effect of selective CO₂ capture and conversion between a porous azo polymer and its supported metal catalyst.