Direct Integration of Functionalized Bridges by One-Step Superacid-Catalyzed Reaction to Fabricate Porous Polymers for CO2 Capture and Separation

Abstract

A novel class of ultra-microporous functionalized porous organic polymers (POPs) was developed starting from glyoxylic acid as a cross-linker and triflic acid as a catalyst on polyaromatic monomers, generating in situ methine bridges with carboxylic acids. This one-pot synthetic method generated functionalized POPs with high connectivity per each aromatic group and a high density of aliphatic carboxylic acids decorating the pore walls. Remarkably, the functional groups were transformed into esters, Na- and Li-carboxylates by post-synthetic modification with high yields, generating polyionic porous polymers. These porous polymers displayed excellent CO₂ adsorption at 298 K and isosteric heat of adsorption with values as high as 50 kJ mol⁻¹ for the Na-containing POP endowed with numerous ionic charges, as estimated by direct measurements with microcalorimetry coupled to CO₂ adsorption isotherms. Dynamic breakthrough experiments on self-supporting monolithic composites demonstrated high selectivity for CO₂ adsorption over N₂ up to 500 for diluted streams and 340 under relevant conditions for carbon capture from flue gases (0.15 CO₂ partial pressure).