Conversion Of Epichlorohydrin Research Articles

CO2 Fixation via epoxide cycloaddition with a highly active and stable MOF-808/GO composite catalyst

The CO2 cycloaddition reaction effectively mitigates the greenhouse effect while producing high-value cyclic carbonates. Metal-organic frameworks (MOFs) have shown promise for CO2 cycloaddition with epoxides; however, the aggregation of MOFs due to high surface energy hinders mass transfer and catalytic performance. By pre-coordinating graphene oxide (GO) to regulate the dispersion of MOF-808, the resulting MOF-808/GO-100 composite catalyst exhibits twice the activity of pristine MOF-808, achieving 92.6% conversion of epichlorohydrin (ECH) with 98.2% selectivity to ECH carbonate without adding any co-catalysts. The incorporation of GO introduces numerous hydroxyl groups on the catalyst surface, serving as hydrogen bonding donors. The oxygen-containing groups on GO can compete with ligands for Zr coordination, generating defective Zr sites. The synergistic effect between defective Zr sites and hydrogen bonding donors collectively promotes epoxide opening. Notably, GO correspondingly enhances the dispersion of MOF-808 and induces mesopore formation through its stacking effect at the interface with MOF-808. Across various epoxide cycloaddition reactions, MOF-808/GO-100 consistently demonstrated optimal performance and maintained high stability over multiple reaction cycles.

Non-hydrolytic sol-gel synthesis of amine-functionalized silica: Template- and catalyst-free preparation of mesoporous catalysts for CO2 valorization

Carbon dioxide utilization presents an important and topical research topic. However, the performance of catalysts needed for CO2 transformations does not achieve the necessary levels for their widespread application. To this end, we decided to study non-aqueous condensations providing amine-functionalized silica catalysts, possibly active in CO2-epoxide cycloaddition reaction. While non-hydrolytic sol-gel method is well-known for its efficiency in providing highly porous Lewis and Brønsted acid metallosilicates, here we show for the first time its application for the preparation of silica-based catalysts containing basic groups. First, the reaction conditions were screened to reproducibly obtain porous materials with preserved amine moieties. These were identified as follows: silicon tetraacetate and bridging tertiary amine silanes as precursors, toluene as a solvent, and temperature between 160 and 180 °C. In such a way, materials with up to 776 m2 g−1 and 1.58 cm3 g−1 were obtained in one-step process, without any template, after conventional drying step. Next, the amine-functionalized materials were tested in CO2-epoxide coupling providing cyclic organic carbonates with high selectivity (>99 %) and moderate activity (up to 86 % epichlorohydrin conversion after 1 h at 120 °C and 10 bar CO2). The characterization of spent catalysts revealed a presence of cyclic organic carbonates at the catalyst surface as well as conversion of tertiary amine groups to quaternary ammonium moieties.

Imidazolium bromide substituted magnesium phthalocyanine polymers: New promising materials for CO2 conversion

The conversion of CO2 with epoxides into the corresponding cyclic carbonates represents a green approach to transform a waste into value-added products. To promote this conversion, a catalyst in needed. This study presents the synthesis of two cross-linked materials composed of magnesium phthalocyanine and imidazolium bromide moieties: MgPc-BIBI-Br and MgPc-SIBI-Br. Magnesium phthalocyanines are cost-effective and versatile catalysts, synthesized in high yield from low-cost precursors and can be easily modified for specific needs. Imidazolium bromide groups play a crucial role as well, acting as a nucleophile source essential to promote the ring-opening process of the epoxide. The materials have been extensively characterized through analytical and spectroscopic techniques and tested as catalysts in the conversion of epichlorohydrin into 4-chloromethyl-1,3-dioxalan-2-one. They both achieved excellent catalytic performance (maximal TON values of 3070 for MgPc-SIBI-Br and 1903 for MgPc-BIBI-Br) and recyclability (both recyclable at least for 4 cycles). The reported results represent an improvement if compared to similar materials already reported in the literature in which the addition of external nucleophilic species (e.g. TBAB, BMIM-Br, etc.) is needed. To the best of our knowledge, this work is the first example in which imidazolium bromide and magnesium phthalocyanine moieties are combined in bifunctional polymeric materials that convert CO2 into cyclic carbonates via heterogeneous catalysis.

Chemical fixation of carbon dioxide into cyclic carbonates by multi-hydroxyl carboxylic acid ionic liquids under atmospheric pressure

Transformation CO2 to valuable chemical products is a favorable way for reducing CO2 emissions. However, the developed methodologies usually suffer from harsh reaction conditions. In this work, a series of ionic liquids featuring anions with multiple hydroxyl carboxylic acid moieties (MHCAIL1–5) were facilely synthesized, which exhibiting remarkable catalytic activity in conversion CO2 and various epoxides to cyclic carbonates without metal, co-catalysts, solvents and halogen under atmospheric pressure. The hydroxyl groups and carboxylate anion in ILs serve as hydrogen bond donors and nucleophiles to activate epoxides, ensuring exceptional conversion. Notably, the catalytic performance of MHCAIL-5 resulted in 99 % conversion of epichlorohydrin and 99 % selectivity of chloropropene carbonate at 80 ℃ within 3 h at atmospheric pressure. Proposed mechanism has been postulated according to NMR, FT-IR and Mass spectrometry results. Furthermore, due to the high thermodynamic and chemical stability of ionic liquids, this catalytic system demonstrated excellent recyclability.

The sustainable catalytic conversion of CO2 into value-added chemicals by using cobaloxime-based double complex salts as efficient and solvent-free catalysts

Cobalt(III)-based catalysts for CO2 fixation are widely applied for the synthesis of cyclic carbonates from epoxides and CO2 under suitable and solvent-free conditions. Inspired by the enhancing catalyst strategy for highly efficient CO2 conversion into useful products, here we show that the cobaloximes (1–3) and corresponding to different double cobaloxime salts (4–6), and their single salts with simple counterions (7–9) were prepared and evaluated as an efficient catalyst for the coupling of CO2 and epoxides into cyclic carbonates. The structure of synthesized target cobaloximes was characterized using a combination of 1H, 13C, and 11B NMR spectra, FT-IR spectra, UV–Vis spectra, LC-MS/MS spectrometers, melting point, and elemental analysis techniques. Although the prepared cobaloxime-based catalytic systems were studied in a wide range of epoxide substrates, the highest catalytic activity was observed in the conversion of epichlorohydrin under suitable conditions. After seeing highly efficient catalytic conversion and selectivity of the newly synthesized cobaloximes (1–3) and different cobaloxime-based double complex salts (4–9), the effect of epoxide, base, reaction time, temperature, and CO2 pressure was investigated for these catalysts. The best conversion was performed in the presence of a catalyst (6) (the double cobaloxime salt bearing 4-t-butyl) and DMAP as a co-catalyst, with a 98% yield and 99% selectivities.

Highly Robust {In2}-Organic Framework for Efficiently Catalyzing CO2 Cycloaddition and Knoevenagel Condensation.

To improve the catalytic performance of metal-organic frameworks (MOFs), creating higher defects is now considered as the most effective strategy, which can not only optimize the Lewis acidity of metal ions but also create more pore space to enhance diffusion and mass transfer in the channels. Herein, the exquisite combination of scarcely reported [In2(CO2)5(H2O)2(DMF)2] clusters and 2,6-bis(2,4-dicarboxylphenyl)-4-(4-carboxylphenyl)pyridine (H5BDCP) under solvothermal conditions generated a highly robust nanoporous framework of {[In2(BDCP)(DMF)2(H2O)2](NO3)}n (NUC-65) with nanocaged voids (14.1 Å) and rectangular nanochannels (15.94 Å × 11.77 Å) along the a axis. It is worth mentioning that an In(1) ion displays extremely low tetra-coordination modes after the thermal removal of its associated four solvent molecules of H2O and DMF. Activated {[In2(BDCP)](Br)}n (NUC-65Br), as a defective material because of its extremely unsaturated metal centers, could be generated by bromine ion exchange, solvent exchange, and vacuum drying. Catalytic experiments proved that the conversion of epichlorohydrin with 1 atm CO2 into 4-(chloromethyl)-1,3-dioxolan-2-one catalyzed by 0.11 mol % NUC-65Br could reach 99% at 65 °C within 24 h. Moreover, with the aid of 5 mol % cocatalyst n-Bu4NBr, heterogeneous NUC-65Br owns excellent universal catalytic performance in most epoxides under mild conditions. In addition, NUC-65Br, as a heterogeneous catalyst, exhibits higher activity and better selectivity for Knoevenagel condensation of aldehydes and malononitrile. Hence, this work offers a fresh insight into the design of structure defect cationic metal-organic frameworks, which can be better applied to various fields because of their promoted performance.

POSS-based polyionic liquids for efficient CO2 cycloaddition reactions under solvent- and cocatalyst-free conditions at ambient pressure.

The conversion of CO2 into value-added chemicals has become an imminent research topic and the cycloaddition of CO2 with a C1 resource to produce cyclic carbonates is a promising pathway for CO2 utilization. Herein, a series of POSS-based polyionic liquids (PILs) were synthesized by the copolymerization of octavinyl polyhedral oligomeric silsesquioxane (POSS) with an imidazolium ion linker. The prepared PILs have the characteristics of hydrogen bond donors, halogen atom sites, stable pore structures, and thermal stability, and are used as heterogeneous catalysts for the cycloaddition of epoxides with carbon dioxide. The effect of linkers on the cycloaddition is investigated by tuning the ratio of POSS units to imidazolium ions. Under the optimized conditions, the conversion of epichlorohydrin can reach 99.18% at atmospheric pressure with neither co-catalysts nor solvents. It is concluded that the reaction of the cycloaddition of epoxides with carbon dioxide follows pseudo-first-order kinetics. Moreover, the presence of the catalysis of PILs leads to a significant decrease in the activation energy barrier for cycloaddition. The catalyst can be facilely recovered due to its high stability, and only a slight decrease in conversion was observed after five successive runs. In addition, the mechanism of PILs catalyzing the cycloaddition reaction of epoxides with CO2 is proposed. This work not only provides a sustainable and green process for CO2 cycloaddition, but also highlights the potential of using PILs for CO2 utilization.

Metal-Free N-Doped Carbons for Solvent-Less CO2 Fixation Reactions: A Shrimp Shell Valorization Opportunity.

High anthropogenic CO2 emissions are among the main causes of climate change. Herein, we investigate the use of CO2 for the synthesis of organic cyclic carbonates on metal-free nitrogen-doped carbon catalysts obtained from chitosan, chitin, and shrimp shell wastes, both in batch and in continuous flow (CF). The catalysts were characterized by N2 physisorption, CO2-temperature-programmed desorption, X-ray photoelectron spectroscopy, scanning electron microscopy, and CNHS elemental analysis, and all reactivity tests were run in the absence of solvents. Under batch conditions, the catalyst obtained by calcination of chitin exhibited excellent performance in the conversion of epichlorohydrin (selected as a model epoxide), resulting in the corresponding cyclic carbonate with 96% selectivity at complete conversion, at 150 °C and 30 bar CO2, for 4 h. On the other hand, in a CF regime, a quantitative conversion and a carbonate selectivity >99% were achieved at 150 °C, by using the catalyst obtained from shrimp waste. Remarkably, the material displayed an outstanding stability over a reaction run time of 180 min. The robustness of the synthetized catalysts was confirmed by their good operational stability and reusability: ca. (75 ± 3)% of the initial conversion was achieved/retained by all systems, after six recycles. Also, additional batch experiments proved that the catalysts were successful on different terminal and internal epoxides.

Triphenylimidazolium-incorporated, benzbisimidazole-linked porous organic polymers as efficient catalyst for CO2 conversion

The cycloaddition of CO 2 to epoxides is now becoming one of the most important CO 2 -fixation reactions due to the 100% atom efficiency together with the wide application of cyclic carbonates. However, such a cycloaddition reaction often requires efficient catalysts owing to the intrinsically inert nature of CO 2 . Herein, we report the synthesis of triphenylimidazolium-incorporated, benzbisimidazole-linked porous organic polymer (namely PBPI-IL) by polycondensation of 1,2,4,5-benzenetetramine with triphenylimidazole-containing tetraaldehyde followed by post-treatment with iodomethane. The as-synthesized PBPI-IL2 network with intact benzbisimidazole ring possesses an ionization degree of 31.94 mol% and a specific surface area of 350 m 2 g −1 , which is capable of efficiently catalyzing the cycloaddition of CO 2 to epoxides, i.e., 99% conversion and 99% selectivity in the transformation of epichlorohydrin at 60 °C under atmospheric CO 2 pressure. Moreover, the PBPI-IL2 network can be readily recycled and reused for at least 6 times. The highly catalytic activity of PBPI-IL2 network can be ascribed to the H-bonding interaction between benzbisimidazole ring and epoxides, the Lewis base-Lewis acid and π-π bonding interactions between benzbisimidazole ring and CO 2 molecule, as well as the high nucleophilicity of I − anion. • PBPI is prepared by polycondensation of BPI with BTAT. • PBPI-IL is obtained through the post-treatment with CH 3 I. • PBPI-IL can catalyze the cycloaddition of CO 2 to epoxides under mild conditions. • The conversion of epichlorohydrin and selectivity can reach up to 99% and 99%. • The PBPI-IL2 catalyst can be readily recycled and reused for at least 6 times.

Amine-functionalized bimetallic Co/Zn-zeolitic imidazolate frameworks as an efficient catalyst for the CO2 cycloaddition to epoxides under mild conditions

Amine-functionalized bimetallic zeolitic imidazolate framework-8 (Co/Zn-ZIF-A) with 3-amino-1,2,4-triazole (Atz) was synthesized by a post-synthetic modification and utilized as a heterogeneous catalyst for the synthesis of cyclic carbonates from CO2 and epoxides. Different amine contents in Co/Zn-ZIF-A materials were controlled by adjusting the ligand exchange reaction time of the of 2-mIM with Atz. Co/Zn-ZIF-A-24 h with the highest amine contents (32% of Atz) achieved an excellent result of 99% conversion of epichlorohydrin with high selectivity of > 99% after 24 h without co-catalyst and solvent under mild conditions (80 oC, 1 bar CO2). The enhanced catalytic activity is attributed to the acid-base synergistic effect by the combination of bimetallic systems consisting of Zn and Co as Lewis acid sites and the abundant Lewis bases sites of -NH2, -NH groups from Atz ligand. A kinetic study of the cycloaddition reaction over Co/Zn-ZIF-A-24 h confirmed an approximately first-order dependence on the epichlorohydrin concentration and CO2 pressure with an activation energy of approximately 39.5 kJ mol-1. Co/Zn-ZIF-A-24 h catalyst showed good reusability with no obvious loss in catalytic activity during five recycling runs and its structural stability was also confirmed. A plausible reaction mechanism of Co/Zn-ZIF-A catalyst for CO2-epoxide cycloaddition was proposed.

Core-shell catalyst with synergistic hydroxyl and nitrogen active sites for CO2 cycloaddition

Developing heterogeneous catalyst with multiple active sites has been a hot-spot for cycloaddition of CO2 with epoxides to value-added chemicals. In this work, a new N- doped carbon/silica core-shell material (M-41/CN) with special hydroxy (Si-OH) and pyridinic N active sites were designed and synthesized. The prepared M-41/CN showed good features: (1) exhibited synergistic effects of Si-OH groups (Acid sites) and pyridinic N species (Lewis basic sites), and (2) held porous structure with specific surface area reaching 308.7 m2/g. The M-41/CN exhibited excellent catalytic activity and stability for cycloaddition of CO2 with epichlorohydrin, with conversion of epichlorohydrin >98% after 4th reuse. Hence, the M-41/CN with acid-base duality offers a new choice for preparing low-cost, environment-friendly and high-efficiency catalysts for CO2 conversion.

Experimental and computational studies of Zn (II) complexes structured with Schiff base ligands as the efficient catalysts for chemical fixation of CO2 into cyclic carbonates

The present work aimed at comparably studying the catalytic performance of Zn (II) complexes applied as the efficient catalysts in accelerating the transformation of CO2 into cyclic carbonates. The physicochemical properties of the synthesized complexes were determined by XRD, NMR, FT-IR, TGA, NH3-TPD, CO2-adsorption. The synthesized samples were found to possess the Lewis acid/basic sites derived from the zinc ions and nitrogen-containing ligands, which can synergistically catalyze the coupling reaction. In addition, the sample containing iodide ion ligands showed the highest catalytic performance compared with other Zn (II) complexes, suggesting that the amount and distribution of the Lewis acid sites were not the primary factors for determining the catalytic activity, and the difference in activity of halogen ion ligands (I−, Br−, Cl−) has a larger influence on the coupling process, which made the CO2 insertion and ring closure of the formed intermediate more easily occur when iodide ion ligands participated. It can be drawn that the catalytic activity of the Zn (II) complexes was simultaneously associated with halide ion ligands and substitution group of the ligand. Moreover, 98.62% conversion of epichlorohydrin (ECH) and 96.97% selectivity to chloropropene carbonate (TOF=56.65 h − 1) was achieved at the optimal operation parameters (110 °C, 2.5 MPa, 8 h, 1.25 wt.% catalyst of ECH). Furthermore, the proposed pathway of CO2 coupling with epoxide was confirmed by DFT calculation, with the result confirming that the process of epoxide ring opening was the key step for the coupling reaction.

Riveting Hydroxyl Ionic Liquids onto Melem Oligomers for CO2 Cycloaddition into Cyclic Carbonates

AbstractThe product of cyclic carbonates from carbon dioxide (CO2) and epoxides under solvent‐free and co‐catalyst‐free conditions is an environmental‐friendly and economical route. However, the core of this route lies in the design and preparation of efficient and low‐cost catalysts. In this work, hydroxyl ionic liquids (HEIMBr) modified melem oligomers (CN‐HEIMBr) was fabricated and used for the cycloaddition of CO2 into cyclic carbonates. The characterizations for these catalysts, such as XPS, TGA, SEM, FT‐IR, etc, all confirmed that HEIMBr was successfully grafted onto melem oligomers. The synergistic effects of edge defects (−NH and −NH2) of melem oligomers, hydroxyl groups and halogen anions of ionic liquids were conductive to promoting CO2 cycloaddition. The influences of CO2 pressure, catalyst dosage, reaction time and temperature on the conversion and yield were investigated in detailed. In the conditions of co‐catalyst‐free and solvent‐free, the conversion of epichlorohydrin (ECH) was 99 % and the yield of chloropronene carbonate (CPC) was 97 % under optimal conditions (140 °C, 2.0 MPa, 2 h, catalyst 0.1 g, ECH 30 mmol). Moreover, the catalyst was reused at least five runs without any significantly loss of catalytic performance. Furthermore, a credible multi‐synergetic catalytic mechanism was proposed. An originality idea was provided for designing high‐efficiency catalysts for coupling of CO2 and epoxides, and put forward the multi‐synergistic effects of catalysts on CO2 conversion.

A Bifunctional Cationic Covalent Organic Polymer for Cooperative Conversion of CO2 to Cyclic Carbonate without Co-catalyst

A cationic covalent organic polymer with bifunctional active site was synthesized, which was treated by N, N'-bis(5-bromomethylsalicylaldehyde)ethylenediamine (salen ligand) and tris(1H-imidazol-1-yl) triazine (TIT) in the presence of aluminum ethoxide. The bifunctional cationic covalent organic polymer was investigated by various characterization technologies including PXRD, FT-IR, XPS, TG, SEM, EDS, N2-adsorption and CO2-adsorption. In this polymer, aluminum acts as lewis acid site and bromine ion acts as nucleophile, cooperatively catalyzing the cycloaddition reaction of CO2 and epoxides. Due to its cooperative effect, a higher catalytic activity was found to exhibit 98.1% conversion of epichlorohydrin under optimized conditions (Initial pressure 1.0 MPa, 0.57 mol% catalyst of COP-Al, 90 °C, reaction time 18 h, in the absence of a co-catalyst). Notably, the heterogeneous catalyst still showed good activity and stability after five cycles. A salen-based cationic covalent organic polymers (COP-Al) was used as a bifunctional catalyst for the cycloaddition reaction of CO2 and epoxides with high activity under solvent-free and co-catalyst-free conditions.

Design and Development of Novel Continuous Flow Stirred Multiphase Reactor: Liquid–Liquid–Liquid Phase Transfer Catalysed Synthesis of Guaiacol Glycidyl Ether

Phase transfer catalysed (PTC) reactions are used in several pharmaceutical and fine chemical industrial processes. We have developed a novel stirred tank reactor (Yadav reactor) to conduct batch and continuous liquid–liquid–liquid (L-L-L) PTC reactions. The reactor had a provision of using three independent stirrers for each phase, thereby having complete control over the rate of mass transfer across the two interfaces. In the continuous mode of operation, the top and bottom phases were continuously fed into the reactor while the middle phase was used as a batch. All three stirrers were used independently, thereby having independent control of mass transfer resistances. The reactor in a batch mode showed higher conversion and selectivity compared to a conventional batch reactor. L-L-L PTC reaction in the continuous mode was successfully performed without loss of the middle catalyst phase and with steady conversion and selectivity. The reaction of guaiacol with epichlorohydrin was conducted as a model reaction, with a 76% conversion of epichlorohydrin, 85% selectivity of guaiacol glycidyl ether, and the middle catalyst phase was stable throughout the process.

Imidazolium ionic liquid functionalized UiO-66-NH2 as highly efficient catalysts for chemical fixation of CO2 into cyclic carbonates

Imidazolium ionic liquids functionalized UiO-66-NH 2 MOFs were synthesized by two different approach, further applied as efficient catalysts for the catalytic conversion of CO 2 into cyclic carbonates. The functionalized UiO-66-NH 2 were investigated using various characterization technologies including XRD, NMR, FT-IR, XPS, TG-DTG, TEM, N 2 -adsorption, and NH 3 -TPD. The octahedron structure of UiO-66-NH 2 becomes rough after UiO-66-NH 2 interacted with 1-(4-carboxybutyl)-3-methylimidazolium bromide via amidation, while some small grains were formed around UiO-66-NH 2 species when UiO-66-NH 2 was functionalized by 1-(3-sulfopropyl)-3-methylimidazolium bromide ([SPMIM]Br) via the H 2 N– and HSO 3 – interaction. Moreover, when [SPMIM]Br was grafted onto the surface of UiO-66-NH 2 , a higher catalytic activity was found to exhibit 98.12% conversion of epichlorohydrin (ECH) and 98.23% selectivity to chloropropene carbonate (CPC) under optimized conditions (Initial pressure 2.5 MPa, 1.2 wt% catalyst of ECH, 95 °C, reaction time 8 h). No significant deactivation of the catalyst was observed after the [SPMIM]Br functionalized UiO-66-NH 2 was reused three times. Furthermore, several additional coupling reactions were investigated with other epoxides as substrates. Chemical fixation of CO 2 into cyclic carbonates over ionic liquid functionalized UiO-66-NH 2 . • Two different approach was applied for the synthesis of functionalized UiO-66-NH 2 . • CO 2 can be efficiently converted into various cyclic carbonates over functionalized UiO-66-NH 2 . • 98.12% conversion of epichlorohydrin and 98.23% selectivity to chloropropene carbonate was obtained. • The difference of imidazolium ionic liquids was also studied by DFT calculations.

Facile Green Synthesis of New Copper-Based Metal–Organic Frameworks: Experimental and Theoretical Study of the CO2 Fixation Reaction

Two new entangled Cu­(II)-based metal–organic frameworks (MOFs) have been synthesized, namely [Cu­(BDC)­(BPDB)0.5]n (PNU-25) and [Cu­(NH2-BDC)­(BPDB)0.5]n (PNU-25-NH2), using a H2O–MeOH solvent mixture. Both the PNU-25 and PNU-25-NH2 MOF materials were characterized by various analytical techniques, and their potential for catalyzing CO2 fixation into cyclic carbonates at an atmospheric pressure, at a low reaction temperature, and in the neat conditions was demonstrated. The amine-functionalized PNU-25-NH2 exhibited a significantly high conversion of epichloro­hydrin (ECH) at 1 bar of CO2 pressure, at 55 °C, and with a moderate catalyst amount (1 mol%), with over 99% selectivity toward the corresponding cyclic carbonate of ECH. The superior catalytic activity of PNU-25-NH2 may be attributed to its high amount of acidic–basic sites and large BET surface area in comparison with the PNU-25. The PNU-25-NH2 catalyst could be reused up to four cycles without compromising its structural integrity and the ECH conversion. The reaction mechanism of the CO2 and ECH cycloaddition reaction mediated by PNU-25-NH2 was investigated in detail, based on the experimental inferences and periodic calculations of density functional theory (DFT). The energy barrier of the rate-determining step of the PNU-25-NH2/TBAB-catalyzed reaction was significantly lower than the barriers of the rate-determining steps of non-catalyzed and TBAB-catalyzed reactions.

Multiobjective Optimization for the Greener Synthesis of Chloromethyl Ethylene Carbonate by CO2 and Epichlorohydrin via Response Surface Methodology

In this paper, a statistical analysis with response surface methodology (RSM) has been used to investigate and optimize process variables for the greener synthesis of chloromethyl ethylene carbonate (CMEC) by carbon dioxide (CO2) and epichlorohydrin (ECH). Using the design expert software, a quadratic model was developed to study the interactions effect between four independent variables and the reaction responses. The adequacy of the model was validated by correlation between the experimental and predicted values of the responses using an analysis of variance (ANOVA) method. The proposed Box-Behnken design (BBD) method suggested 29 runs for data acquisition and modelling the response surface. The optimum reaction conditions of 353 K, 11 bar CO2 pressure, and 12 h using fresh 12% (w/w) Zr/ZIF-8 catalyst loading produced 93% conversion of ECH and 68% yield of CMEC. It was concluded that the predicted and experimental values are in excellent agreement with ±1.55% and ±1.54% relative errors from experimental results for both the conversion of ECH and CMEC yield, respectively. Therefore, statistical modelling using RSM can be used as a reliable prediction technique for system optimization for greener synthesis of chloromethyl ethylene carbonate via CO2 utilization.

Solvent-Free cycloaddition of carbon dioxide and epichlorohydrin catalyzed by surface-attached imidazolium-type poly(ionic liquid) monolayers

Design and synthesis of effective catalysts for the conversion of epoxy compounds to cyclic carbonate under the presence of carbon dioxide molecules is essential for the utilization of carbon dioxide. Herein, we report that the surface-attached imidazolium-type poly(ionic liquid) bearing amine moieties is an efficient catalyst for the conversion of epoxy compound and carbon dioxide to cyclic carbonate. The effect of chemical structure of the synthesized catalyst and the reaction conditions on the catalytic efficiency is systematically studied. The results show that the catalyst with bromide anion can effectively catalyze the reaction under 1.5 MPa carbon dioxide pressure at 120 °C with the catalyst content of 10 mg mL−1, reaching the conversion rate up to 90 %. Moreover, the synthesized catalyst can be separated from the cyclic carbonate products by centrifugation. The recyclability and reversibility measurements reveal that the decay of the catalytic activity is mainly resulted from the adsorption of the cyclic carbonate products on the catalysts. The catalytic activity of the synthesized catalyst towards conversion of epichlorohydrin and carbon dioxide to cyclic carbonate can be recovered after extraction of the adsorbed cyclic carbonate products.

Comparison of Catalytic Activity of ZIF-8 and Zr/ZIF-8 for Greener Synthesis of Chloromethyl Ethylene Carbonate by CO2 Utilization

The catalytic activity of both ZIF-8 and Zr/ZIF-8 has been investigated for the synthesis of chloromethyl ethylene carbonate (CMEC) using carbon dioxide (CO2) and epichlorohydrin (ECH) under solvent-free conditions. Published results from literature have highlighted the weak thermal, chemical, and mechanical stability of ZIF-8 catalyst, which has limited its large-scale industrial applications. The synthesis of novel Zr/ZIF-8 catalyst for cycloaddition reaction of ECH and CO2 to produce CMEC has provided a remarkable reinforcement to this weak functionality, which is a significant contribution to knowledge in the field of green and sustainable engineering. The enhancement in the catalytic activity of Zr in Zr/ZIF-8 can be attributed to the acidity/basicity characteristics of the catalyst. The comparison of the catalytic performance of the two catalysts has been drawn based on the effect of different reaction conditions such as temperature, CO2 pressure, catalyst loading, reaction time, stirring speed, and catalyst reusability studies. Zr/ZIF-8 has been assessed as a suitable heterogeneous catalyst outperforming the catalytic activities of ZIF-8 catalyst with respect to conversion of ECH, selectivity and yield of CMEC. At optimum conditions, the experimental results for direct synthesis of CMEC agree well with similar literature on Zr/MOF catalytic performance, where the conversion of ECH, selectivity and the yield of CMEC are 93%, 86%, and 76%, respectively.