Study On The Solvent To Recycle The Catalyst In The Process Of Synthesis Of Ethylene Glycol By Catalytic Hydration

The method of direct hydration with ethylene oxide (EO) is the main way to synthesize ethylene glycol (EG) today. As far as above 85% (wt) water in the products must be evaporated by using massive energy, this has brought about such disadvantages as long process flows, large equipments and enormous waste of energy and affected the cost of production of EG seriously. Recently, the studies of catalytic hydration to synthesize EG have shown good prospects in solving above-mentioned problems and have a virtue of high reaction conversion and selectivity as well, so this method is drawing more and more attention. This paper was based on the former researches about EG and had mainly studied the solvent to recycle the catalyst in the process of synthesis of EG by catalytic hydration. The first step, the experiments were done to determine the solubility of catalyst in many solvents chosen by certain demands and glycerol was found in which the solubility of NY is greater than it in the EG. And then the effects of glycerol on the original reaction were discussed. Secondly, the static and dynamic performances of solvents were respectively studied in chapter 3 and chapter 4, by which the soluble performances of NY in glycerol and EG were deeply compared in the following aspects such as the solubility of NY in the solvents, viscosity and density of the solutions composed of NY and the solvent. Besides, the soluble performances of NY1 and NY3 in the solvents were discussed, too. This paper has shown that if glycerol is used as the solvent to recycle the catalyst in the process of synthesis of ethylene glycol by catalytic hydration and the temperature of circulating solutions is controlled to above 120℃, this not only can raise the soluble quantity of NY but also viscosity of circulating solutions has no distinct variation, so it can reduce the quantity of circulating solution, save the energy and make progress for the original process. The main contents of this paper include the following aspects: 1) At first, a lot of solvents were filtrated which were based on the characteristics of this process and catalysts being used. This research showed that the solubility of NY in glycerol was better than it in EG. And then the effects of glycerol on the original reaction of catalytic hydration were discussed by orthogonal experiments. In the end of chapter 2, the optimal reaction conditions containing glycerol were got. 2) The research about the static performances of the solvents was carried out by following methods. The viscosity and density of the saturated solutions composed of catalyst and solvent were respectively determined and these physical data were analyzed and compared in detail. At last, the better solvent to recycle the catalyst and the temperature of circulate solution were selected in the end of chapter 3. 3) The purpose of the research about the dynamic performances of the solvents was to discuss the differences between the static experiment and the dynamic experiment of the solvents and provide the foundation for the industrialized applications of glycerol. The experimental methods were mainly to compare the viscosities of the solutions and the mass concentrations of catalysts in two saturated solutions, one of which was got by rectifying and the other was accordingly put up by mixing directly. 4) The research about the catalysts of NY1 and NY3 showed that the solubility of NY3 in glycerol and EG were both greater than NY1 and viscosities of the saturated solutions composed of NY3 and the solvents were lower than NY1 under the same temperature. Therefore, if glycerol was used as the solvent to recycle the catalyst in the process of synthesis of EG by catalytic hydration, it was better to choose NY3 as the catalyst.