Valorization of CO2 through the Synthesis of Cyclic Carbonates Catalyzed by ZIFs

Abstract

One way to exploit CO2 is to use it as a feedstock for the production of cyclic carbonates via its reaction with organic epoxides. As far as we know, there is still no heterogeneous catalyst that accelerates the reaction in a selective, efficient and industrially usable way. Cobalt and zinc-based zeolitic imidazole frameworks (ZIFs) have been explored as heterogeneous catalysts for this reaction. In particular, we have prepared ZIF-8 and ZIF-67 catalysts, which have been modified by partial replacement of 2-methylimidazole by 1,2,4-triazole, in order to introduce uncoordinated nitrogen groups with the metal. The catalysts have shown very good catalytic performance, within the best of the heterogeneous catalysts tested in the cycloaddition of CO2 with epichlorohydrin. The catalytic activity is due ultimately to defects on the outer surface of the crystal, and varies in the order of ZIF-67-m > ZIF-67 > ZiF-8-m = ZIF-8. Notably, reactions take place under mild reaction conditions and without the use of co-catalysts.

Enhancing Trace Metal Extraction from Wastewater: Magnetic Activated Carbon as a High-Performance Sorbent for Inductively Coupled Plasma Optical Emission Spectrometry Analysis

“…The secondary electron micrograph (Figure 2) shows the cobalt-doped carbon crystallites. The microstructure reminds us of the original ZIF, where there has simply been a contraction of the particles without losing their original cubo-octahedral shape [80]. In addition, it is possible to observe from the secondary electron micrograph that the particle size of the ZIF is 1 µm.…”

Sustainable Synthesis of Zeolitic Imidazolate Frameworks at Room Temperature in Water with Exact Zn/Linker Stoichiometry

“…All these specifics make ZIFs special MOFs [ 5 ]. They are being intensively investigated in applications such as energy storage [ 6 ], electrocatalysis [ 7 ], heterogeneous catalysis [ 8 ], drug delivery [ 9 ], enzyme support [ 10 ], environmental remediation [ 11 ] or gas separation [ 12 ], among others. Nevertheless, another key factor of such widespread use of ZIFs is their synthesis under benign conditions, at room temperature and with water as the solvent.…”

Pillar-Layered Porous Metal–Organic Frameworks with Co2N2O8 Clusters and Tetragonal Ligands for CO2 Conversion

“…For example, the microporous Cu-based MOF material Cu 2 (ABTC) constructed based on azobenzene tetracarboxylic acid and Cu impeller building units exhibits excellent performance in the catalytic fixation of CO 2 and epoxides, 34 with a high conversion rate of styrene oxidation (96%) and a yield of styrene carbonate generation (90%) under mild conditions (CO 2 1 atm, 60 °C, 8 h). Narciso 35 In this work, flexible/semiflexible chain bis-imidazole bimb and bidpe ligands, as well as the crossed carboxylic acid H 4 L ligand were selected to synthesize two kinds of 3D porous materials (MOFs 1−2) with Co 2 N 2 O 8 metal clusters through the solvothermal method (Scheme 1). MOFs 1−2 were characterized using infrared spectra, thermogravimetry (TG), single-crystal X-ray diffraction (SC-XRD), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS).…”

“…For example, the microporous Cu-based MOF material Cu 2 (ABTC) constructed based on azobenzene tetracarboxylic acid and Cu impeller building units exhibits excellent performance in the catalytic fixation of CO 2 and epoxides, with a high conversion rate of styrene oxidation (96%) and a yield of styrene carbonate generation (90%) under mild conditions (CO 2 1 atm, 60 °C, 8 h). Narciso et al partially replaced 1,2,4-triazole with 2-methylimidazole to modify ZIF-8 and ZIF-67, increasing the base sites. Without the use of a cocatalyst, ZIF-8-m and ZIF-67-m were able to mildly catalyze the conversion of epichlorohydrin to 3-chloropropene carbonate with carbon dioxide, achieving a selectivity of 100%.…”