It remains an intriguing challenge to convert CO2 into valuable chemicals under atmosphere conditions by porous heterogeneous catalysts. Ionic metal-organic frameworks (iMOFs) have not only permanent porosity and tunable structures but also programmable components, which make them have the potential applications in capture and conversion of CO2.

Recently, the research group led by Prof. CAO Rong from Fujian Institute of Research on the Structure of Matter (FJIRSM) of the Chinese Academy of Sciences (CAS) reported a series of functional iMOFs focused on the chemical fixation of CO2 into cyclic carbonates. These targeted porous materials have been successfully created based on the theory of "Inorganic-organic sites synergistic catalysis".

For the first time, a microporous cationic imidazolium functionalized Zr-MOF, (I-)Me-UiO-66, was synthesized via reticular chemistry and post-synthetic modification. (I-)Me-UiO-66, containing Brnsted acid sites and nucleophilic iodine ions, could effectively convert various epoxides into cyclic carbonates without the use of co-catalyst under 1 bar CO2 condition (Chem.Sci.).

Later, an ionic multivariate MOF, containing both the zinc porphyrin and imidazolium bromide, was obtained by tandem post-synthetic modification method. This MOF showed more superior performance than other iMTV-MOFs herein in the conversion of allyl glycidyl ether (AGE) into corresponding cyclic carbonates under 1 bar CO2 conditions. This work has provided a feasible approach for the preparation of ionic metalloporphyrin based MOF materials (Inorg.Chem.).

Recently, a mesoporous cationic Cr-MOF denoted FJI-C10 containing imidazolium moieties, Lewis acidic Cr3+ sites and free halogens, was constructed by a topology-guided synthesis. Compared with neutral MIL-101, FJI-C10 exhibited enhanced CO2 adsorption ability (20.2 wt%, 273 K, 1 bar). On the other hand, FJI-C10 could convert various epoxides into cyclic carbonates without the use of co-catalyst under atmospheric pressure (Chem.Commun. Inside Cover).

Based on this, those porous heterogeneous catalytic systems for chemical fixation of CO2 into cyclic carbonates have been systematically reviewed in Coord. Chem. Rev.

Schematic views of various iMOFs for the capture and conversions of CO2. (Image by Prof. CAO’s Group)

Contact:

Prof. CAO Rong

Fujian Institute of Research on the Structure of Matter

Chinese Academy of Sciences

Email: rcao@fjirsm.ac.cn