A facile one-pot preparation of porphyrin-based microporous organic polymers for adsorption of carbon dioxide, ethane, and methane

Abstract

Achieving a cost-effective preparation of 3D porphyrin-based microporous organic polymers (PMOPs) for the adsorption and separation of carbon dioxide (CO₂), ethane (C₂H₆), and methane (CH₄) remains difficult. In this study, two 3D PMOP networks that originated from triphenylphosphine and tetraphenylsilane units for CO₂, C₂H₆, and CH₄ adsorption/separation, PMOP-P and PMOP-Si, were successfully fabricated by a facile one-pot method using tri(4-formylphenyl)phosphine (TFPP) and tetrakis(4-aldehydephenyl)silane (TFPSi) with inexpensive pyrrole, respectively. The as-prepared PMOPs consisted of roughly spherical particles with specific surface areas between 645 and 814 m² g⁻¹ and pore sizes smaller than 2 nm. In addition, the PMOPs showed medium CO₂, C₂H₆, and CH₄ gas adsorption performances. Compared with PMOP-P, PMOP-Si the tetraphenylsilane moiety displayed higher microporosity. It also exhibited CO₂, C₂H₆, and CH₄ gas uptakes of up to 138.9, 71.0, and 14.7 mg g⁻¹, respectively, at 273 K and 1 bar. The 138.9 mg g⁻¹ CO₂ uptake exceeded those of previously reported PMOP materials. Moreover, the as-prepared PMOP-P containing triphenylphosphine units possessed a smaller pore size than PMOP-Si and exhibited C₂H₆/CH₄ and CO₂/CH₄ selectivities as high as 24.3 and 10.9 at 273 K, respectively, derived from the initial slope method. The results are helpful for the future design and construction of microporous organic polymers originating from triphenylphosphine and tetraphenylsilane units for simple gas adsorption and separation.