Catalyst For Cycloaddition Of CO2 Research Articles

A2B2‐zinc(II)porphyrin/divinylbenzene Copolymer as Efficiently Bifunctional Catalyst for Cycloaddition of CO2 with Epoxides

A2B2‐zinc(II)porphyrin/divinylbenzene Copolymer as Efficiently Bifunctional Catalyst for Cycloaddition of CO2 with Epoxides

Mesostructured Bifunctional ZnBr2/g‐C3N4 Catalysts Towards Efficient Cocatalyst‐Free Cycloaddition of CO2 to Propylene Carbonate

AbstractCatalytic cycloaddition of CO2 with propylene oxide (PO) is a sustainable pathway for the synthesis of propylene carbonate (PC), and the design of efficient heterogeneous catalysts is a hot research topic in both C1 chemistry and functional materials. In this work, graphitic carbon nitride (g‐C3N4) materials were prepared using urea (U) and melamine (M) as precursors through one‐step thermal condensation and then applied as catalyst supports for ZnBr2. As heterogeneous catalysts, the synthesized composites (ZnBr2/g‐C3N4‐MU) exhibited higher activity in the cycloaddition reaction of CO2 to PC than ZnBr2/g‐C3N4‐M and ZnBr2/g‐C3N4‐U. The preparation temperature of ZnBr2/g‐C3N4‐MU could affect the distributions of nitrogen species and acidic strength, which thus determined the final catalytic activity. More importantly, the loading of ZnBr2 not only introduced acidic sites but also enhanced the strength of alkaline sites of g‐C3N4‐MU, enabling ZnBr2/g‐C3N4‐MU materials as acid–base bifunctional catalysts in cycloaddition of CO2 with PO.

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.

Monomethylated Tröger's-base-containing polyimidazolinium salt as an efficient catalyst for cycloaddition of CO2 to epoxides

In this work, the model reaction of benzaldehyde and ammonium chloride has been studied by detailed product analysis and characterization. Subsequently, amarine and iso-amarine hydrochlorides (1, 2), dimethylated amarine and iso-amarine ionic salts (3, 4), together with monomethylated Tröger's-base ionic salt (6) have been separately synthesized and characterized. In addition, their catalytic performance towards the cycloaddition of CO2 to epichlorohydrin is compared under identical conditions. It is observed that their catalytic activity follows the order of 3 ≈ 4 >6 > 1 ≈ 2. Inspired by the highly catalytic activity of 3, 4 and 6, a novel monomethylated Tröger's-base-containing polyimidazolinium salt (namely PMDD-IL) has been synthesized by one-pot reaction of Tröger's-base-containing dialdehyde monomer (MDD) with ammonium chloride followed by treatment with excess iodomethane in the presence of sodium hydride. The as-synthesized PMDD-IL network exhibits highly catalytic activity towards the cycloaddition of CO2 to epoxides, providing nearly quantitative selectivity (99%) and conversion (99%) over a wide substrate scope of epoxides at atmospheric CO2 pressure (epichlorohydrin, 100 °C/10 h; epibromohydrin, 100 °C/12 h; glycidyl phenyl ether, 100 °C/24 h; styrene oxide, 100 °C/24 h; and 2-butyloxirane, 100 °C/24 h). The excellent catalytic activity of PMDD-IL network can be ascribed to the high nucleophilicity of iodine anion along with the strong interactions between PMDD-IL network and CO2 molecules.

Coordination Synergy between Iridium Photosensitizers and Metal Nanoclusters Leading to Enhanced CO2 Cycloaddition under Mild Conditions.

The achievement of photocatalytic CO2 and epoxide cycloaddition under mild conditions such as room temperature and atmospheric pressure is important for green chemistry, which can be achieved by developing coordination synergies between catalysts and photosensitizers. In this context, we exploit the use of coordinate bonds to connect pyridine-appended iridium photosensitizers and catalysts for CO2 cycloaddition, which is systematically demonstrated by 1H nuclear magnetic resonance titration and X-ray photoelectron spectroscopic measurements. It is shown that the hybrid Ir(Cltpy)2/Mn2Cd4 photocatalytic system with coordination synergy exhibits excellent catalytic performance (yield ≈ 98.2%), which is 3.75 times higher than that of the comparative Ir(Cltpy-Ph)2/Mn2Cd4 system without coordination synergy (yield ≈ 26.2%), under mild conditions. The coordination between the Mn2Cd4 catalyst and the Ir(Cltpy)2 photosensitizer enhances the light absorption and photoresponse properties of the Mn2Cd4 catalyst. This has been confirmed through transient photocurrent, electrochemical impedance, and electron paramagnetic tests. Consequently, the efficiency of cycloaddition was enhanced by utilizing mild conditions.

Tetracosanuclear nickel complexes as effective catalysts for cycloaddition of carbon dioxide with epoxides.

A series of well-defined tetracosanuclear nickel complexes 3-7 facilely produced by one-pot synthesis were active catalysts for cycloaddition of CO2 and cyclohexene oxide (CHO). These nickel complexes were doughnut-like supramolecular coordination complexes involving eight repeating units, and each of them contains one Schiff base ligand and three nickel(II) ions. Notably, the 24-nuclear nickel cluster complex 3 in combination with nucleophilic additives was the most efficient catalyst to mediate CO2 coupling with CHO to generate CO2-based cis-cyclohexene carbonates. In addition to CO2/CHO cycloaddition, complex 3 was also found to effectively couple CO2 with other alicyclic epoxides, generating the corresponding cyclic carbonates. Additionally, kinetic investigations for CO2 cycloaddition of CHO using 3 were reported.

Insight into the Varying Reactivity of Different Catalysts for CO2 Cycloaddition into Styrene Oxide: An Experimental and DFT Study.

The cycloaddition of CO2 into epoxides to form cyclic carbonates is a highly sought-after reaction for its potential to both reduce and use CO2, which is a greenhouse gas. In this paper, we present experimental and theoretical studies and a mechanistic approach for three catalytic systems. First, as Lewis base catalysts, imidazole and its derivatives, then as a Lewis acid catalyst, ZnI2 alone, and after that, the combined system of ZnI2 and imidazole. In the former, we aimed to discover the reasons for the varied reactivities of five Lewis base catalysts. Furthermore, we succeeded in reproducing the experimental results and trends using DFT. To add, we emphasized the importance of non-covalent interactions and their role in reactivity. In our case, the presence of a hydrogen bond was a key factor in decreasing the reactivity of some catalysts, thus leading to lower conversion rates. Finally, mechanistically understanding this 100% atom economy reaction can aid experimental chemists in designing better and more efficient catalytic systems.

Novel MOF catalysts based on calix[4]arene for the synthesis of propylene carbonate from propylene oxide and CO2

In this study, novel composite materials based on calix[4]arene with hydroxyl groups in the arene “bowl” (K-OH) and the aluminum(III) 2-aminoterephthalate metal organic framework (NH2-MIL-101(Al), MIL) have been synthesized according to in situ or “bottle around ship” strategy. The effect of the synthesis method, i.e., MW-assisted technique (MW) and the solvothermal procedure (Solv), on the structural, morphological, textural and catalytic properties of MIL/K-OH composites was demonstrated. Catalytic performance of the MIL/K-OH(MW) and MIL/K-OH(Solv) composites was studied in solvent-free coupling of CO2 and propylene oxide (PO) to produce propylene carbonate (PC) at 0.8 MPa of CO2 and 80 °C. The activity of the MIL/K-OH(Solv) catalyst was higher in comparison with MIL/K-OH(MW) material as a result of the differences in the textural properties. The binary system MIL/K-OH(MW)/[n-Bu4N]Br was demonstrated to be a promising catalyst for cycloaddition of CO2 to PO. In its presence, the conversion of PO was 77 % with 99 % selectivity towards PC at 1.2 MPa of CO2, 50 °C for 24 h.

Ionic-containing hyper-crosslinked polymer: A promising bifunctional material for CO2 capture and conversion

Hyper-crosslinked polymers (HCPs) are a category of porous materials with the high specific surface area, abundant pore canal, and tunable structure. A very challenging topic is to fabricate ion-pair active sites into the skeleton structure of HCPs, which can endow HCPs with specific CO2 separation and catalytic characters. In this work, a series of hyper-crosslinked polymers with the high specific surface area and tunable ion-pair active sites are fabricated by using a one-pot method with simultaneous quaternization and Friedel-Crafts reactions. These ion-pair-containing hyper-crosslinked polymers (IHCPs) are served as adsorbents for selective separation of CO2 from CH4 and N2. It is found that CO2 uptake of IHCP-2 reaches 2.87 mmol·g−1 at 273 K and 1 bar, which is higher than that of the same type of ionic polymers that have been reported in the literature. The high CO2 adsorption capacity is due to the abundant microporous and high specific surface area of as-prepared IHCPs. More importantly, these IHCPs can also be used as recyclable catalysts for cycloaddition of CO2 and epoxides under metal- and cocatalyst-free conditions, affording corresponding cyclic carbonates in excellent yields. The high catalytic activity is attributed to synergistic contributions of the hierarchical pores and nucleophilic ion pair’s structure. This research provides an alternative strategy for development of bifunctional function materials towards efficient CO2 capture and conversion.

Agile construction of bifunctional bipyridine-based hyper-cross-linked ionic polymers for efficient CO2 adsorption and conversion

Porous organic polymers (POPs) are a very promising CO2 adsorption material due to their well-developed pore structure and high specific surface area, but they generally have no catalytic activity for cycloaddition of CO2 and epoxides. Introducing ionic sites into the polymer backbone can endow POPs with unique properties such as both adsorption and catalytic conversion of CO2. In this work, several novel bipyridine-based hyper-cross-linked ionic polymers (HCIPs) were fabricated by using a one-pot method with simultaneous quaternization and Friedel-Crafts reactions, and HCIPs with hierarchical pore structure and high specific surface area (up to 1448 m2·g−1) are acquired by adjusting the structure of polymerized monomers. The plentiful micro-mesoporous and indigenous ion pair active centers of the as-prepared HCIPs are conducive to the adsorption and conversion of CO2. The results showed that these bipyridine-based HCIPs can not only effectively adsorb CO2, but also serve as the metal-free catalysts for cycloaddition of CO2 with epoxides, affording the highest CO2 uptake of 2.75 mmol·g−1 at 0 °C and 1.0 bar and moderate to good yields of cyclic carbonates. This study provides a feasible strategy for the design and synthesis of structurally controllable HCIPs for adsorption and conversion of CO2.

Melem based mesoporous metal-free catalyst for cycloaddition of CO2 to cyclic carbonate

A highly efficient melem based mesoporous metal-free catalyst with amino and hydroxyl groups was successfully developed by template method with melamine as precursor and nano-SiO2 as template. In the absence of any co-catalyst and solvent, the catalyst mp-CN-450 exhibits high catalytic activity for catalytic cycloaddition reaction between CO2 and polyfunctional epoxides, and the epoxides conversion and corresponding cyclic carbonates selectivity are 99.7 % and 99.5 %, respectively. And the catalyst has hardly loss of catalytic activity after being reused for four cycles. The characterization results disclose that the high catalytic activity of the catalyst is closely related to its large specific surface area, abundant mesoporous structure and synergistic effect of N species and hydroxyl groups of melem hydrates. Additionally, through the study of different N-containing compounds, it was found that the primary amine may underwent a ring-opening reaction with epoxide. But with the addition of CO2, amine groups prior to reacted with CO2 to form carbamate salt, avoided the formation of by-products, thereby improved the selectivity of cyclic carbonate. Finally, based on the above research, a possible reaction mechanism for the coupling of CO2 to epoxides was proposed.

Tuning the catalytic properties for cycloaddition of CO2 to propylene oxide on zeolitic-imidazolate frameworks through variation of structure and chemical composition

A series of Zn- and Co containing zeolitic-imidazolate frameworks (ZIFs), such as ZIF-8(Zn)/ZIF-67(Co), MAF-5(Zn)/MAF-5(Co), and MAF-6(Zn)/MAF-6(Co), were investigated as catalysts for the synthesis of propylene carbonate (PC) from propylene oxide (PO) and CO2. The effect of the chemical composition, textural, structural and physicochemical properties on their activity was investigated. It was found that the activity of Zn-containing materials was higher in comparison with Co-based materials. Moreover, the yield of a PC was decreased with increasing Co content in structure of mixed Zn,Co-ZIFs (ZIF-8/ZIF-67) that was related to the accessibility of active centers to reagents and the strength of their interaction with CO2 and propylene oxide. The catalytic performance of Zn-ZIFs was found to improve with increasing the size of pore aperture due to the guest molecule facile diffusion and accessibility of the active site for reagent. In general, based on the results of the present work, the Zn-ZIFs could be considered as promising catalysts for cycloaddition of CO2 to epoxides and thereby opens new paths for further research.

One-pot construction of ionic liquid-functionalized MOF material as the catalyst for CO2 cycloaddition under atmospheric pressure

Carboxylic ionic liquid 1-propionic acid-3-methylimidazolium chloride (CFIL) was immobilized in a metal-organic framework (MOF) material NH2-MIL-101 in one-pot by the in-situ assembly method; as a heterogeneous catalyst with multiple active sites, the catalytic performance of NH2-FMOF-CFIL in the cycloaddition of CO2 with epichlorohydrin (ECH) to synthesize chloropropylene carbonate (CPC) was investigated. The immobilized of CFIL in NH2-MIL-101 was proved by Fourier transform infrared spectroscopy (FT-IR) and elemental analysis, while the powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and N2 adsorption-desorption measurements demonstrated that CFIL neither damages the crystal structure nor blocks the pore of NH2-MIL-101, but induce the formation of mesopores. The catalytic reaction results reveal that there is a catalytic synergy between imidazole N and Cl− on CFIL and Cr3+ and amino group on MOF, which endow the NH2-FMOF-CFIL composite excellent catalytic performance in the cycloaddition of CO2 with ECH; under mild conditions, viz., 0.1 MPa CO2, 25–70 °C and without using any solvent and cocatalyst, the CPC yield reaches 99% after reaction for 24 h. Moreover, the crystal structure and high activity of the NH2-FMOF-CFIL catalyst are well preserved even after reuse for 5 cycles.

Triazinyl-imidazole polyamide network as an efficient multi-hydrogen bond donor catalyst for additive-free CO2 cycloaddition

A single-component synergistic catalytic system, in which multiple active sites act on a substrate with minimal energy input and promote efficient conversion of the substrate, is considered to be the most advanced technology for simulating enzyme catalytic reaction. The design principles of this technology are the driving force behind the pursuit of cost-effectiveness in industrial production, but the challenges remain formidable. Herein, three periodic mesoporous polyamides with triazine-derived networks (PMP-TDNs) were prepared via "one-pot" polycondensation, and used as non-metallic catalysts for cycloaddition of CO2 with epoxides without any additives to synthesis cyclic carbonates. The composition and physicochemical properties of PMP-TDNs were evaluated via different analytical methods to explore the crucial factors affecting catalytic activity. Especially, the activity of PMP-TDNs-MI with multiple hydrogen bond donor (HBD) and high-density N basic sites have been tested effectually; the results has demonstrated a superior reactivity for the cycloaddition of CO2 and a wide range of epoxides with reusability. The kinetics and thermodynamics of cycloaddition of CO2 with propylene epoxide by PMP-TDNS-MI were investigated, and the cooperative catalytic mechanism between the versatile active sites of catalyst was revealed based on the experimental results.

Immobilization poly(ionic liquid)s into hierarchical porous covalent organic frameworks as heterogeneous catalyst for cycloaddition of CO2 with epoxides

The chemical fixation of CO2 into high value-added chemicals is of significant potential and sustainability to address the energy and ecological issues. To achieve great catalytic performance on the transformation of CO2, it is pivotal to strategically integrating several multifunctional and synergetic functionalities into the catalyst design and catalytic system construction. Herein, the poly(ionic liquid)-hierarchical porous covalent organic framework (PIL-HPCOF) hybrids were successfully synthesized via the formation of HPCOF through hard-template method, followed by in-situ polymerization of mono-vinyl decorated ionic liquids (ILs). The resultant PIL-HPCOF hybrids possess excellent versatility, with micropores providing high surface area to enhance CO2 uptake capacity and macropores supplying sufficient pore volume to promote mass transport of substrates. As a proof of concept, the conversion of CO2 with epoxides to produce cyclic carbonates was selected as a model reaction, which catalytic performance was obviously promoted by using PIL-HPCOF hybrids as the catalyst as compared to those of independent PIL and the PIL-COF hybrids with only micropores. Thus, it enables such a metal-free catalysis proceeds under much mild conditions (CO2 (1 MPa), 90 °C) and with broad substrates tolerance. These results supply the basis to design efficient and stable catalysts for CO2 conversion.

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.

Investigation of Using Multi-Hydroxyl Ionic Liquid Polymer as Catalyst to Produce Propylene Carbonate

Ionic liquid with a single hydroxyl group, 1-(2-hydroxyl-ethyl)-3-methylimidazolium bromide (HEMIMB), was prepared. It was found that HEMIMB could be an efficient catalyst for CO2 cycloaddition to propylene oxide to produce propylene carbonate (PC). An ionic liquid polymer with multi-hydroxyl groups poly(1-2-hydroxyl-ethyl)-3-vinylimidazolium bromide (PHEVIMB) was also prepared. In this study, both catalytic reaction performances of HEMIMB and PHEVIMB were investigated. Results showed that product separation and catalyst recycles in the process of PHEVIMB catalytic reaction system was much more efficient with a yield of 55.5%, even after three consecutive catalyst reuses. Meanwhile, the separation was less time-efficient for homogeneous catalytic system of HEMIMB molecules with a single hydroxyl group despite of a yield of 92.4%. When it comes to practical industrial process design, the single component with multifunctional ionic liquid polymer, as catalyst, may be considered effective and friendly process.

Porous nitrogen-rich covalent organic framework for capture and conversion of CO2 at atmospheric pressure conditions

Abstract A porous nitrogen-rich imine-linked covalent organic framework (COF1) has been synthesized by Schiff-base condensation reaction of 4,4′-azodianiline (AZO) and benzene-1, 3, 5-tricarboxaldehyde (BTA) under solvothermal conditions and characterized by various techniques. Owing to the presence of basic imine (-C N) and -azo (-N N) functionalized 1D channels, COF1 exhibits high affinity for CO2 with high isosteric heat of adsorption (Qst) value of 32.3 kJ/mol. Further, the COF1 supported ZnBr2 acts as an excellent recyclable catalyst for cycloaddition of CO2 to epoxides resulting in cyclic carbonates with high yield and 100% selectivity under solvent-free mild conditions of 1 bar of CO2. Further, the coordination of Zn(II) to basic –C N group was supported by XPS studies and theoretical calculations. Interestingly, COF1 shows excellent recyclability and can be recycled for several cycles without substantial loss of catalytic activity and structural rigidity. The high CO2 affinity combined with excellent thermal stability and catalytic activity make COF1 a promising candidate material for efficient fixation of carbon dioxide.

Phosphonium-Based Porous Ionic Polymer with Hydroxyl Groups: A Bifunctional and Robust Catalyst for Cycloaddition of CO2 into Cyclic Carbonates.

The integration of synergic hydrogen bond donors and nucleophilic anions that facilitates the ring-opening of epoxide is an effective way to develop an active catalyst for the cycloaddition of CO2 with epoxides. In this work, a new heterogeneous catalyst for the cycloaddition of epoxides and CO2 into cyclic carbonates based on dual hydroxyls-functionalized polymeric phosphonium bromide (PQPBr-2OH) was presented. Physicochemical characterizations suggested that PQPBr-2OH possessed large surface area, hierarchical pore structure, functional hydroxyl groups, and high density of active sites. Consequently, it behaved as an efficient, recyclable, and metal-free catalyst for the additive and solvent free cycloaddition of epoxides with CO2. Comparing the activity of PQPBr-2OH with that of the reference catalysts based on mono and non-hydroxyl functionalized polymeric phosphonium bromides suggested that hydroxyl functionalities in PQPBr-2OH showed a critical promotion effect on its catalytic activity for CO2 conversion. Moreover, PQPBr-2OH proved to be quite robust and recyclable. It could be reused at least ten times with only a slight decrease of its initial activity.

Quaternary phosphonium salt-functionalized Cr-MIL-101: A bifunctional and efficient catalyst for CO2 cycloaddition with epoxides

Integration of synergic Lewis acid sites and nucleophilic anions that can facilitate ring-opening of epoxide is a good way to develop efficient catalyst for cycloaddition of CO2 with epoxides. Herein, we prepared a novel metal-organic framework (MOF) catalyst (Cr-MIL-101-[BuPh3P]Br) through grafting quaternary phosphonium salt ionic liquid (IL) on Cr-MIL-101 by a facile post-synthetic approach. The introduction of phosphonium salt IL highly improves the catalytic activity and stability compared with the parent Cr-MIL-101-NH2. In the absence of any solvent and co-catalyst, Cr-MIL-101-[BuPh3P]Br showed excellent catalytic activity for the cycloaddition reaction under moderate reaction conditions. Under optimized conditions, the yield and TOF of propylene carbonate can be achieved 97.8% and 1086.7 h−1, respectively. This is because the synergetic interaction of dual functional sites including Cr3+ as Lewis acid sites in MOF and Br- as nucleophile in IL could promote the ring-opening of epoxide through the coordination of Cr3+ sites with O atom and the nucleophilic attack of Br- on the less sterically hindered β-carbon atom of epoxide, respectively. Comparison with other reported ILs-functionalized Cr-MIL-101 or other kinds of MOFs catalysts reveals that Cr-MIL-101-[BuPh3P]Br has superior catalytic performance and potential. Moreover, Cr-MIL-101-[BuPh3P]Br as a heterogeneous catalyst also showed good chemical stability and reusability.