Carbon Dioxide Adsorption within Porous Porphyrin Networks

Porphyrin-based films containing nanoscale crystallites of covalent organic frameworks (MPOR-COFs, where M = H2, Cu2+, Zn2+) have been synthesized, and their adsorption properties have been studied. The adsorption isotherms for CO2 indicate distinct variations in adsorption energetics and capacity among films prepared with different porphyrin precursors. H2POR-COF films exhibited enhanced CO2 capture performance compared to those containing zinc and copper in their porphyrin rings. The heat of adsorption and the adsorption capacity for the metal-free films were about 50% lower and 100% higher than those of the metal-containing films. Increased crystallinity in the films was found to reduce their CO2 adsorption capacities. This work highlights the viability of our synthetic approach to create tunable porphyrin-based frameworks for gas separation applications.