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oai:ojs.www.eurjchem.com:article/460 2012-08-06T14:50:19Z eurjchem:ART driver

Synthesis of ethylene carbonate from cyclocondensation of ethylene glycol and urea over ZnO•Cr2O3 catalyst system controlled by co-precipitation method Bhadauria, Sheenu Saxena, Samidha Prasad, Rajendra Sharma, Prabhakar Prasad, Rajendra Dwivedi, Reena Urea Zinc chromite Ethylene glycol Co-precipitation Cyclocondensation Ethylene carbonate ZnO·Cr2O3 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·ZnCr2O4 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. Atlanta Publishing House LLC 2012-06-30 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion application/pdf https://www.eurjchem.com/index.php/eurjchem/article/view/460 10.5155/eurjchem.3.2.235-240.460 European Journal of Chemistry; Vol. 3 No. 2 (2012): June 2012; 235-240 2153-2257 2153-2249 eng https://www.eurjchem.com/index.php/eurjchem/article/view/460/PDF