Introduction of mesopores effectively enhances the accessibility of volatile organic compounds within the micropores of covalent triazine frameworks

Abstract

Porous organic polymers (POPs) with abundant pores have great potential for the treatment of volatile organic compounds (VOCs). However, narrow micropores increase gas diffusion resistance and limit the accessibility of VOCs within the micropores. Here, we have synthesized microporous covalent triazine frameworks (mpCTFs) with abundant mesopores using nano-silica. And the effects of the introduced mesopore structure on the sorption performances of CTF were further investigated by 1,2-dichloroethane adsorption. The results indicate that mpCTF12.5 has the most suitable mesopore volume, and its specific surface area and total pore volume are 2.40 and 2.17 times that of CTF, respectively. Meanwhile, the mpCTF12.5 exhibited excellent adsorption performance for methanol, ethanol, acetone, benzene, ethyl acetate, 1,2-dichloroethane and toluene due to the multiple C-H…O, C-H…Cl, O-H…N and C-H…π interactions between VOCs and mpCTFX framework, demonstrated via DFT calculations. Additionally, the two-component gas-competitive adsorption behavior and the impact of water vapor on the adsorption performance of mpCTFX were investigated, with the adsorption mechanism thoroughly analyzed using the GCMC model. The introduction of abundant mesopores undoubtedly shortened the diffusion paths within the micropores of CTFs, significantly enhancing their accessibility for VOC adsorption. This study presents a viable strategy to improve the performance of porous materials in VOC adsorption applications.