Tailored porous structure and CO2 adsorption capacity of Mg-MOF-74 via solvent polarity regulation

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2023-11, Vol.476, p.146845, Article 146845
• Main Authors: Ma, Mengdan, Zhou, Anning, Hong, Tao, Jia, Xinyu, Liu, Moxuan
• Format: Article
• Language: English
• Subjects: CO2 adsorbents; Crystal structure; Kamlet-Taft method; Mg-MOF-74; Polarity parameter
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2023.146845

[Display omitted] •Mg-MOF-74 samples with different microstructure and CO2 adsorption performance were synthesized under different solvent conditions.•β/α value of different solvent mixtures was estimated by the Kamlet-Taft method.•Correlation between β/α value and Mg-MOF-74 microstructure was built.•CO2 adsorption capacity was tuned via solvent polarity regulation. Metal-organic frameworks (MOFs) are promising materials for CO2 adsorption and capture. The unique crystal structure and the open porous structure of MOFs are key factors affecting their CO2 adsorption performance, but the precise tuning of MOF structures remains a challenge. Herein, we applied the Kamlet-Taft method to investigate the effect of solvent proton-supplying/accepting capaity (β/α parameters) on the structure and CO2 adsorption performance of Mg-MOF-74 by tuning the reaction solvent polarity. It was found that the ratio of the nucleation rate/growth rate of Mg-MOF-74 could be effectively controlled by adjusting the β/α value of the solvent, realizing the regulation of the crystal structure and morphology of Mg-MOF-74. In addition, the size of solvent molecules played a crucial role in the pore size of Mg-MOF-74. Interestingly, the solvent molecules were competitively coordinated with ligands and participate in the growth of Mg-MOF-74 upon decreasing the β/α value. The crystal structure, morphology and pore size of Mg-MOF-74 could be precisely regulated by the β/α value and molecular size of the reaction solvent, and the highest performing Mg-MOF-74 exhibited a CO2 adsorption capacity of 7.38 mmol/g.