Synthesis Of Ethylene Carbonate Research Articles

Synthesis of Ethylene Carbonate by Urea Transesterification Using Zeolitic Imidazolate Framework Derived Fe-Doped ZnO Catalysts.

The development of environmentally friendly and efficient methods for the synthesis of ethylene carbonate (EC) is crucial for advancing carbon capture, utilization, and storage technologies. Herein, we present the synthesis of EC through the transesterification of urea with ethylene glycol (EG) using a zeolitic imidazolate framework (ZIF) derived Fe-doped ZnO catalyst (Fe;ZnO-ZIF). The Fe;ZnO-ZIF catalyst, prepared by incorporating Fe dopant atoms into a ZnO-ZIF template, demonstrates excellent catalytic activity, achieving high conversion of reactants and superior selectivity toward EC at 160 °C for 150 min under an applied vacuum (160 mmHg). Based on the thermogravimetric, X-ray spectroscopic, and temperature-programmed desorption analysis, the simultaneous presence of strong Lewis acidic and basic sites in Fe;ZnO-ZIF enables its excellent catalytic performance toward EC synthesis with high selectivity. Acidic sites activate the carbon center in urea, while basic sites facilitate the nucleophilic attack on urea by deprotonation of EG. This synergistic reaction pathway resulting from the interaction between the strong Lewis acidic and basic sites promotes nucleophilic attacks of EG on urea, leading to significantly higher conversion efficiency and selectivity, compared to the commercial benchmark ZnO. Although the establishment of a continuous reaction system which takes into account cyclability and stability of the catalysts is further required in the future, our research reported herein provides valuable insights into the design of synergistic, localized active sites for EC synthesis and contributes to the development of sustainable carbon utilization technologies for achievement of net-zero emissions.

Hyperbranched Poly(ether-siloxane)s Containing Ammonium Groups: Synthesis, Characterization and Catalytic Activity.

In this article we report an easy synthetic route towards hyperbranched polyglycerols (Amm-HBPGs) containing trimethylammonium groups and siloxane or hydroxyl end-groups. Siloxane derivatives of Amm-HBPGs were synthesized in an efficient five-step procedure including an anionic ring opening copolymerization of the phthalimide-epoxy monomer with glycidol, followed by reactions with allyl bromide, hydrosililation with hydrogenheptamethyltrisiloxane, hydrazinolysis of phthalimide groups and quaternization of resulting amine groups with methyl iodide. Hydroxyl derivatives were obtained by quaternization of previously reported aminated HBPG’s with methyl iodide. Polymeric products were characterized using various NMR techniques, FTIR, and elemental analysis. Both Amm-HBPGs were shown to be effective in catalysis of addition of CO2 to oxirane. The hydrophilic catalysts showed higher efficiency but synthesis of ethylene carbonate was accompanied by formation of small amounts of ethylene glycol. The siloxane-containing catalyst was easily separable from reaction mixture showing high potential in the process of converting carbon dioxide into valuable chemical raw materials.

Synthesis of organic carbonates from alcoholysis of urea: A review

ABSTRACTOrganic carbonates are green compounds with a wide range of applications. They are widely used for the synthesis of important industrial compounds including monomers, polymers, surfactants, plasticizers, and also used as fuel additives. They can be divided into two main classes: cyclic and linear carbonates. Dimethyl carbonate (DMC) and diethyl carbonate (DEC) are the important linear carbonates. Carbonyl and alkyl groups present in DMC and DEC make them reactive and versatile for synthesizing various other important compounds. Ethylene carbonate (EC), glycerol carbonate (GC) and propylene carbonate (PC) are well-known cyclic organic carbonates. Phosgenation of alcohols was widely used for synthesis of organic carbonates; however, toxicity of raw materials restricted use of phosgenation method. A number of new non-phosgene methods including alcoholysis of urea, carbonylation of alcohols using CO2, oxy-carbonylation of alcohols, and trans-esterfication of alcohols and carbonates have been developed for synthesizing organic carbonates. Carbonylation of alcohols is preferred as it helps in utilization and sequestration of CO2, however, poor thermodynamics due to high stability of CO2 is the major obstacle in its large scale commercialization. Oxy-carbonylation of alcohols offers high selectivity but presence of oxygen poisons the catalyst. Recently, alcoholysis of urea has received more attention because of its inexpensive abundant raw materials, favorable thermodynamics, and no water-alcohol azeotrope formation. Also, ammonia evolved in this synthesis route can be recycled back to urea by reacting it with CO2. In other words, this method is a step towards utilization of CO2 as well. This article reviews synthesis of DMC, DEC, GC, PC, and EC from urea by critically examining various catalysts used and their performances. Mechanisms have been reviewed in order to give an insight of the synthesis routes. Research challenges along with future perspectives have also been discussed.

Quantum-chemical study on thermal transformations of urea in ethylene glycol

Thermal decomposition of urea in ethylene glycol with formation of isocyanic acid and ammonia was studied at the B3LYP/6-311++G(df,p) level of theory. The decomposition process is efficiently catalyzed by monomeric and dimeric forms of ethylene glycol. Ethylene glycol dimer formed via intermolecular hydrogen bonding is a stronger acid than the monomeric species, which is responsible for the higher catalytic activity of the former. Ethylene glycol associates efficiently catalyze addition of ammonium to isocyanic acid in the synthesis of ethylene carbonate.

Synthesis of Ethylene Carbonate from Urea and Ethylene Glycol over La(NO<sub>3</sub>)<sub>3</sub> Catalyst

Synthesis of ethylene carbonate (EC) from urea and ethylene glycol was investigated in a batch reactor using La(NO3)3 as catalyst. The reaction was performed under reduced pressure to remove the byproduct ammonia. The effect of various operation conditions such as reaction temperature, reaction time and reaction pressure on the EC yield was explored. It was found that the reaction pressure is a key parameter for the formation of EC. At atmospheric pressure, the reaction cannot happen. As the reaction pressure decreases, the EC yield increases significantly. Under the optimum operation conditions, which are reaction pressure 15 KPa, reaction temperature 413 K, reaction time 3 h, and catalyst concentration 10 wt.%, the EC yield can reach to 93%.

Synthesis of ethylene carbonate from cyclocondensation of ethylene glycol and urea over ZnO•Cr2O3 catalyst system controlled by co-precipitation method

ZnO·Cr 2 O 3 catalyst has been synthesized by low temperature, pH controlled co-precipitation route and characterized employing techniques of Brunauer, Emmett, and Teller (BET) surface area measurement, ammonia desorption technique, X-ray diffraction (XRD) and scanning electron microscopy (SEM). These characterizations reveal the catalyst to possess ZnO·ZnCr 2 O 4 composition. The catalysts have been tested for their performance for the first time, in the synthesis of ethylene carbonate from cyclocondensation of ethylene glycol and urea. Effect of catalyst concentration, temperature and molar ratio of reactants has been studied to obtain the optimum conversion and selectivity of ethylene glycol and urea to ethylene carbonate. A maximum yield of 85.75% of ethylene carbonate was obtained at a temperature of 423 K and urea: ethylene glycol molar ratio of 1:1.5. A tentative mechanism of the reaction is proposed on the basis of analysis of reactants, products and modeling of the transition state for the reaction under density function theory using Gaussian09W software. Our studies suggest a consecutive mechanism for the reaction. In the first step, urea and ethylene glycol react to produce 2-hydroxyethyl carbamate, which undergoes further reaction to produce ethylene carbonate (EC) and ammonia.

Synthesis of ethylene carbonate from urea and ethylene glycol over zinc/iron oxide catalyst

AbstractBACKGROUND: Ethylene carbonate (EC) was synthesised via urea and ethylene glycol (EG) over zinc/iron oxide catalyst. By so doing, the by‐product, EG, generated in the process of producing dimethyl carbonate by the transesterification route was converted back to the raw material, EC. The reaction mechanism of EC synthesis was also investigated by means of gas chromatography/mass spectrometry and in situ Fourier transform infrared/attenuated total reflection spectroscopy.RESULTS: Suitable conditions for the preparation of zinc/iron oxide catalyst were as follows: zinc acetate and iron nitrate as precursors, Zn/Fe molar ratio 8:1, calcination temperature 350 °C and calcination time 4 h. Characterisation by X‐ray diffraction revealed two different crystal phases: ZnO and ZnFe2O4. The highest yield of EC (66.1%) was obtained under the following conditions: reaction temperature 150 °C, reaction time 2.5 h, catalyst weight percentage 1.5% and urea/EG molar ratio 1:8. The study of the reaction mechanism revealed that the reaction for the synthesis of EC proceeded in two steps.CONCLUSION: The synergistic effect of ZnO and ZnFe2O4 promoted the catalytic performance of zinc/iron oxide. Copyright © 2008 Society of Chemical Industry

Synthesis of ethylene carbonate from supercritical carbon dioxide/ethylene oxide mixture in the presence of bifunctional catalyst

Ethylene carbonate was rapidly synthesized from supercritical carbon dioxide/ethylene oxide mixture by using as catalyst the system of tetradentate schiff-base aluminum complexes (designated as SalenAlX) coupling with a quaternary ammonium or phosphonium salt. The high rate of reaction was attributed to rapid diffusion and high miscibility of ethylene oxide in supercritical carbon dioxide under employed conditions. Various reaction periods present different formation rate of ethylene carbonate, mainly due to the existence of phase change during the reaction. The synergistic effect of the binary catalyst for ring-opening of ethylene oxide results from nucleophilicity of highly reactive anions of quaternary salts and the electrophilic interaction of SalenAlX with ethylene oxide. The activation of CO 2 was generally initiated by nucleophilic attack of the alcoholate(OCH 2CH 2BrNBu 4) at the carbon atom of CO 2, and weak interaction between the central metal ion of SalenAlX and the lone pairs of one oxygen atom of CO 2. It resulted in the insertion of CO 2 to AlO bond of Salen(X)AlOCH 2CH 2BrN( n-Bu) 4 or SalenAlOCH 2CH 2X to form linear carbonate which was transformed into ethylene carbonate by intramolecular substitution of halides. The experimental results demonstrate that supercritical carbon dioxide could be used as not only an environmentally benign solvent but also a carbon precursor in synthesis.

Novel dicopper(II) complex catalyst: Cu 2(II)(μ-Cl) 2/SiO 2: a study on synthesis of EC from CO 2 reaction with ethylene oxide

A novel process has been developed for synthesis of the silica supported dicopper(II) complex catalyst in which one Cu atom exchanging with two ion exchange sites on the surface of silica. The material was synthesized by reaction of NaOEt modifying the silica surface with dicopper(II) complex [Cu 2(μ-Cl) 2](ClO 4) 2·8H 2O synthesized as pre-catalyst. The structure of the catalyst has been characterized comparatively with the dicopper(II) complex by element analysis, IR spectra and electronic spectra. The reaction of CO 2 with EO (ethylene oxide) has been investigated by temperature programmed desorption and in situ IR spectroscopy. TPD and IR results indicated that CO 2 and EO can be chemisorbed on the surface of the catalyst reversibly and desorbed at 393 and 378 K, respectively. TPSR-MS experiments have shown that EO desorbed dissociatively at high-temperature to form desorbed CO and CH 4 species. CO 2 and EO react on the surface in the temperature range of 353–397 K. In TPSR-IR investigation, EC (ethylene carbonate) produced was detected at 353 K, which is lower than the reported temperature of 393 K for homogeneous catalytic reaction.