Monolithic polar conjugated microporous polymers: Optimisation of adsorption capacity and permeability trade-off based on process simulation of flue gas separation

The challenge in developing porous materials that significantly reduce energy consumption in industrial gas separation lies in striking a balance between adsorption capacity and permeability. Herein, the precise anchoring of polar oxygen adsorption sites in a robust porous conjugated backbone is achieved through the directed selfassembly of building blocks, resulting in the formation of oxygen-enriched conjugated microporous polymers (O-CMPs). O-CMPs serve as attractive porous hosts for the synergistic separation of CO2 and PM in exhaust gases emitted from point sources. As analyzed by surface electrostatic potential, the introduction of oxygen-doped pi-conjugated systems induced surface charge redistribution, enhancing the CO2 quadrupole-dipole effect within a widely distributed microporous network. The O-CMPs exhibited a high CO2 adsorption capacity of 125.84 mg/g at 273 K and 1.0 bar. The monolithic O-CMPs incorporate permanently integrated hierarchical pores with a high micropore ratio. This transport channel can enhance the transfer rate of gas flow while selectively intercepting CO2 and PM. The rigid conjugated molecular chains and hollow nanotube microstructure effectively prevent material densification, yielding a minimal gas permeation resistance of only 5 Pa. Additionally, O-CMPs also demonstrate outstanding stability and PM separation performance under humid and acid/ alkaline condition. The visual process simulations serve to further validate that aforementioned design strategy can optimize the trade-off between adsorption capacity and permeability.