Preparation of isoreticular MIL-101(Cr) based on pre- and post-synthetic strategy and study for carbon dioxide capture

• Published in: Journal of molecular structure 2025-02, Vol.1321, p.139802, Article 139802
• Main Authors: Xi, Fu-Gui, Dong, Zhi-Yun, Li, Yan, Lu, Yu-Sheng, Pan, Cai-Xia, Liu, Cheng-Qi, Qiao, Yong-Sheng
• Format: Article
• Language: English
• Subjects: Amine-MOFs; CO2 adsorption; Formyl; MIL-101; Post-synthetic; Pre-synthetic
• ISSN: 0022-2860
• DOI: 10.1016/j.molstruc.2024.139802

•For the first time, the formyl was introduced to MIL-101(Cr) give rise to MIL-101(Cr)-CHO which would be a powerful platform for further functionalization.•Take advantage of tandem post-synthetic strategy, four aliphatic amines were attached to MIL-101(Cr) by covalent bond.•For MIL-101-TAEA, the isosteric heat of adsorption (Qst) reach to 70.1 kJ/mol at low coverage, and the adsorption capability is 2.34 mmol/g at 298 K under 1 bar CO2 atmosphere, and the adsorption selectivity for CO2/N2 is 172.•MIL-101-TAEA maintain 60 % performance for trace CO2 capture after 16 cycles in a confined space that simulates the atmosphere. The functionalization of MIL-101(Cr) presents a formidable challenge when employing covalent bonds, due to the inherent difficulty of incorporating reactive organic groups into its structure. In this work, we have successfully synthesized MIL-101-CHO tagged with formyl by adopting a pre-synthetic strategy, utilizing 3‑hydroxy-1-oxo-1,3-dihydroisobenzofuran-5-carboxylic acid as the key ligand. Then the integrity of the formyl group and the phase purity of the resulting MIL-101-CHO were rigorously confirmed through FT-IR and 1H NMR characterization. Employing post-synthetic strategy, four amine-MOFs were prepared through cascade reaction of Schiff-base condensation and NaBH4 reduction. The CO2 adsorption properties of all isoreticular MIL-101(Cr) materials were thoroughly investigated. Notably, MIL-101-TAEA demonstrated exceptional performance, with the highest Qst 70.1 kJ/mol at low coverage, the best adsorption capability 2.34 mmol/g at 298 K under 1 bar CO2, and the selectivity 172 for CO2/N2. Furthermore, the good regenerability of MIL-101-TAEA was proved by the CO2 temperature swing adsorption tests. Ultimately, MIL-101-TAEA maintain 60 % performance for trace CO2 capture after 16 cycles under the mimic atmosphere conditions, showing its potential for practical applications in gas separation and capture technologies. [Display omitted] Formyl tagged MIL-101(Cr) framework is synthesized firstly by means of in-situ ring-opening of the ligand. MIL-101-TAEA derived from MIL-101-CHO by covalent reaction exhibits good adsorption capability, selectivity and regenerability for different concentrated CO2.