Efficient Heterogeneous Catalysts For Cycloaddition Research Articles

High-Entropy Lanthanide-Organic Framework as an Efficient Heterogeneous Catalyst for Cycloaddition of CO2 with Epoxides and Knoevenagel Condensation.

Multimetallic synergistic effects have the potential to improve CO2 cycloesterification and Knoevenagel reaction processes, outperforming monometallic MOFs. The results demonstrate superior performance in these processes. To investigate this, we created and characterized a selection of single-component Ln(III)-MOFs (Ln=Eu, Tb, Gd, Dy, Ho) and high-entropy lanthanide-organic framework (HE-LnMOF) using solvent-thermal conditions. The experiments revealed that HE-LnMOF exhibited heightened catalytic efficiency in CO2 cycloesterification and Knoevenagel reactions compared to single-component Ln(III) MOFs. Moreover, the HE-LnMOF displayed significant stability, maintaining their structural integrity after five cycles while sustaining elevated conversion and selectivity rates. The feasible mechanisms of catalytic reactions were also discussed. HE-LnMOF possess multiple unsaturated metal centers, acting as Lewis acid sites, with oxygen atoms connecting the metal, and hydroxyl groups on the ligand serving as base sites. This study introduces a novel method for synthesizing HE-LnMOF and presents a fresh application of HE-LnMOF for converting CO2.

A Pyridinium‐Pyridinium Zinc(II) Porphyrin Ion Porous Organic Polymer as Efficient Heterogeneous Catalyst for Cycloaddition of Epoxides with CO2

AbstractA zinc(II)porphyrin‐based ion porous organic polymer (ZnTPyPBr4‐iPOP) is successfully synthesized from newly designed pyridinium‐functionalized cationic Zn‐porphyrin monomer (ZnTPyPBr4) by free radical self‐polymerization, and is employed as an efficient bifunctional heterogeneous catalyst for CO2 cycloaddition reaction with epoxides. The ZnTPyPBr4‐iPOP exhibits excellent catalytic performance and good substrate expansion in CO2 cycloaddition reaction under solvent‐free and cocatalyst‐free conditions with a TOF as high as 15,500 h−1 for the cycloaddition of CO2 and epichlorohydrin. The synergistic effect of zinc(II)porphyrin as the Lewis acidic site and the Br− anion as the nucleophile in ZnTPyPBr4‐iPOP responds to the high catalytic activity. Moreover, ZnTPyPBr4‐iPOP can easily be recovered and reused at least seven times without the loss of activity. This work provides a valuable approach for the synthesis of novel and efficient heterogeneous catalyst for CO2 cycloaddition.

Four novel Z-shaped hexanuclear vanadium oxide clusters as efficient heterogeneous catalysts for cycloaddition of CO2 and oxidative desulfurization reactions

Chemical fixation of CO2 into C1 source, as a general approach, can effectively alleviate the emission of greenhouse gasses. Whereas, the challenge posed by the need for efficient catalysts with high catalytic active sites still exists. In this work, we reported a series of new hexavanadate clusters, [(C6H6ON)2(C2H8N2)2(CH3O)6VIV6O8] (V6–1), [(C6H6ON)2(C3H10N2)2(CH3O)6VIV6O8] (V6–2), [(C6H6ON)2(C6H14N2)2(CH3O)6VIV6O8] (V6–3) and [(C6H6ON)2(C4H11N2O)2(CH3O)4VIV6O8] (V6–4), assembled by 2-aminophenol and four different kinds of Lewis bases (LB), ethanediamine (en), 1,2-diaminopropane, 1,2-cyclohexanediamine and N-(2-hydroxyethyl)ethylenediamine (ben) together. Among them, the basic unit {V6} cluster featured Z-shaped configuration represents a brand-new example of hexanuclear vanadium clusters. Remarkably, the catalytic tests demonstrated that V6–1 as catalyst displays high catalytic activity in the cycloaddition for the CO2 fixation into cyclic carbonates by virtue of open V sites. As expected, for oxidative desulfurization of sulfides, V6–1 also exhibits satisfied catalytic effectiveness. Furthermore, the recycling test confirmed that catalyst V6–1 may be a bifunctional heterogeneous catalyst with great promise for both CO2 cycloaddition and oxidative desulfurization reactions.

Green synthesized cobalt-bipyridine constructed conjugated microporous polymer: An efficient heterogeneous catalyst for cycloaddition of epoxides via CO2 fixation under ambient conditions

Abstract The conversion of carbon dioxide into valuable cyclic carbonates has been of intensive interest owing to the 100% atomic economy. Conjugated microporous polymers (CMPs) are attractive porous materials contain organic functionalities for applications in gas capture, energy storage, and catalysis. Herein, we developed a new synthesis method of CMP, obtained at room temperature which is one of the “dream reaction”, possessing large surface areas (1356 m2/g) and exhibiting excellent CO2 capture (77.26 cm3/g at 273.15 K/1.00 bar). After loading cobalt acetate, we obtained Co-coordinated CMP (named as TBB-BPY-Co), exhibiting extraordinary activities (turnover frequencies of up to 250 h-1) for the coupling epoxides with CO2 forming cyclic carbonates at room temperature and atmospheric with free-solvent. Moreover, the heterogeneous catalyst showed even better catalytic efficiency than relevant homogeneous catalyst and a higher recyclability (up to 10 times). This study provided an effective and efficient strategy for the carbon dioxide conversion of industrial and economic value.

A Stable Zn-Based Metal–Organic Framework as an Efficient Catalyst for Carbon Dioxide Cycloaddition and Alcoholysis at Mild Conditions

Developing highly efficient heterogeneous catalysts for cycloaddition of CO2 and epoxides to produce cyclic carbonates is promising but challenging. In this work, a novel three-dimensional metal organic framework (MOF) with cylinder pore systems and unsaturated Zn sites has been demonstrated as potent candidate in CO2 fixation at mild and solvent-free conditions. The Zn(atz)(bdc)0.5, where atz = aminotriazole and H2bdc = terephthalic, exhibits microporous nature that can regulate the catalytic interaction of active centers and substrates. The structure stability has been systematically investigated and proven to be sufficient for practical application. Furthermore, the cooperative effects of porosity, CO2 binding affinity, activation centers, and synergism with co-catalyst have been deeply investigated. Moreover, high propylene epoxide conversion (97%) and selectivity (> 99%) have been achieved at mild conditions (60 °C and 1 MPa) with excellent cycle stability. Owing to the well-defined pore system, an obvious substrates selectivity has been clearly observed. A possible catalytic mechanism has been proposed and verified by DFT calculations. Furthermore, the prepared Zn-MOF can also be used as an efficient heterogeneous catalyst for the reaction of epoxides with alcohols to produce β-alkoxy alcohol.

Salen–Cu(II)@MIL-101(Cr) as an efficient heterogeneous catalyst for cycloaddition of CO2 to epoxides under mild conditions

A double active center system, namely Salen–Cu(II)@MIL-101(Cr), was successfully synthesized via the “ship in a bottle” approach, which acted as a bifunctional material for both capture and conversion of CO2 in a single process. For the first time, Salen–Cu(II)@MIL-101(Cr) catalyst was developed for the synthesis of propylene carbonate from CO2 and propylene oxide under room temperature and ambient pressure with a yield of 87.8% over 60 h. Furthermore, the reaction mechanism was also discussed.

Metalated porous porphyrin polymers as efficient heterogeneous catalysts for cycloaddition of epoxides with CO2 under ambient conditions

We have successfully synthesized a porphyrin based porous organic polymer (POP-TPP) from free-radical polymerization of tetrastyrylporphyrin monomer under solvothermal conditions. Besides high surface area (1200m2/g) and high thermal stability, the obtained polymer features open metal chelating sites, and thus the catalytic activities of metalloporphyrins can be reasonably adjusted by introducing various metal ions. After metalation with Co3+, Zn2+, and Mg2+, the Co/POP-TPP, Zn/POP-TPP, and Mg/POP-TPP as heterogeneous catalysts are very active for cycloaddition of epoxides with CO2 to cyclic carbonates at ambient conditions with n-Bu4NBr as a nucleophilic additive. Particularly, under the relatively low CO2 concentration (15% in volume), the activity of heterogeneous Co/POP-TPP catalyst is even higher than that of the corresponding homogeneous Co/TPP catalyst. More importantly, there is no activity loss even if the Co/POP-TPP is recycled for 18 times. The excellent catalytic activity and superior recyclability of the obtained catalysts indicate that the porphyrin based porous organic polymer is a promising candidate for construction of efficient heterogeneous catalysts in the future.