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

Abstract

BACKGROUND: 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.

Rational and Statistical Approaches in Enhancing the Yield of Ethylene Carbonate in Urea Transesterification with Ethylene Glycol over Metal Oxides

“…An identical conclusion was drawn by Bhanage . Bhadauria studied Cr-containing zinc oxide materials, while Zhao investigated Fe-containing materials. In both studies the formation of the spinel phases (ZnCr 2 O 4 and ZnFe 2 O 4 ) was found to be important, promoting EC yield.…”

“…Organic carbonates are a family of commercially important chemicals widely employed as intermediates for a variety of synthetic and industrial applications and also as solvents . Ethylene carbonate (EC) is a reactive starting and intermediate chemical for selective alkoxylation, carbamate formation, and transesterification to produce glycerol carbonate (GC) and linear carbonates such as dimethyl carbonate (DMC), which has drawn great attention as a green solvent, a phosgene replacement, and a fuel additive …”

DFT-Assisted Mechanism Evolution of the Carbonylation of Ethylene Glycol to Ethylene Carbonate by Urea over Zn(NCO)2·2NH3 Catalyst

“…Reaction Mechanism for Uncatalyzed Reactions. From their in situ IR studies on cyclization of urea and EG to EC, Zhao et al 11 concluded that this reaction occurs in two consecutive steps. In the first step, 2-HEC is formed and cyclizes in the second step to produce EC.…”

“…The synthesis of cyclic carbonates from diols and urea has attracted attention recently because of many benefits such as mild operating conditions, high yield, and easy availability of raw materials. Various oxides, such as CaO, La 2 O 3 , MgO, ZnO 2 , Al 2 O 3 , zinc/iron, and ZnO–Cr 2 O 3 , have been used as catalysts. Recent studies on the carbonylation of methanol suggest ZnO to be the best catalyst for these reactions and that ZnO completely dissolves in the reaction mixture, making the reaction homogeneously catalyzed by Zn­(NCO) 2 ·2NH 3 . , It has been suggested that the reaction between EG and urea catalyzed by metal oxides proceeds through a consecutive mechanism.…”

Application of Dimethyl Carbonate Assisted Chemical Looping Technology in the Separation of the Ethylene Glycol and 1,2-Butanediol Mixture and Coproduction of 1,2-Butene Carbonate

“…Cyclic carbonates, especially ethylene carbonate (EC), propylene carbonate (PC), and glycerol carbonate (GC), are significant organic chemical materials and intermediates with a wide range of applications, for example, in organic synthesis, electrochemistry, gas separation, cosmetic additives, and other fields. − The synthesis of cyclic carbonates mainly includes (1) the transesterifications of alcohols with EC or dimethyl carbonate (DMC), (2) the direct carboxylation of alcohols with carbon dioxide, (3) the phosgenation of alcohols, (4) the alcoholysis of urea, and so on. ,,− Among these methods, transesterification of alcohols with EC or DMC is a more efficient way to obtain high-commercial cyclic carbonates under mild conditions. Compared to the other four methods, this method helps to avoid unfavorable thermodynamic equilibrium, low reaction rate, toxic materials, expensive agents, high reaction temperature, and rigorous reaction conditions. ,− Thus, it has been one of the simplest and the most attractive methods for producing cyclic carbonates from alcohols and dialkyl carbonates and is therefore broadly applied in industrial processes. − At present, EC and PC have realized massive production in industries, whereas there is hardly any reported research work on the synthesis of high-value-added five-membered cyclic carbonate, 1,2-butene carbonate (BC), because of the limitation of its preparation raw material 1,2-BDO.…”