Thermal / Kinetic Analysis And Process Study Of Ethylene Oxide Absorbed By Ethylene Carbonate

Ethylene carbonate?EC?,known as the green basic chemical raw material for the 21 st century,was an important organic synthesis intermediate with a wide range of applications.At present,the main method of industrial production of EC was ethylene oxide?EO?and CO₂ addition reaction,which C₂H₄ and O₂ were used as raw materials to produce EO,and then water was used as an absorbent,after absorption,desorption,purification process to obtain pure EO in order to produce EC.This process not only has high energy consumption but also incomplete absorption,so the exploration of new processes and absorbents has become a research hotspot.From an industrial point of view,this paper developed that EC with low specific heat capacity was used as an absorbent in order to absorb EO.A new EO absorptionconversion unit coupling process has been developed to provide important basic data and theoretical support for EO production of EC.The innovative results of the dissertation are as follows:1.VLE data was obtained.A set of equipment was built to measure the solubilities of CO₂,CH₄ and C₂H₄ in ethylene carbonate at 313.15-333.15 K and solubility of EO in EC at 333.15-353.15 K.The results show that the solubilities of the four gases in EC decreased with increasing temperature and decreasing pressure.At the same temperature and pressure,the solubility of EO in EC was the largest,followed by CO₂,and the smallest was CH₄.Under the same pressure,when the temperature was changed,the solubility of CO₂ in EC was most affected by the temperature.When the pressure was changed,the solubility of C₂H₄ was most affected by the pressure.2.The modes and binary interaction parameters were obtained.The traditional nonrandom two-liquid NRTL and Wilson models were used to correlate the solubilities data of four gases in EC.The results show that for the solubilities data of the binary system examined by the two models,the average deviations of the NRTL and Wilson models were 2.1 % and 5.3 %,respectively.The NRTL model parameters obtained by regression were used to predict the solubilities data of the EC-EO-CO₂ ternary system.The average deviation of the prediction results was less than 5 %,which provided the reliability of the model parameters.3.Absorption kinetics and absorption tower experiment.The kinetic data of EC absorption of EO-CO₂ mixed gas was explored at temperature of 333.15-353.15 K,and an absorption tower was designed and constructed.The absorption data and optimized conditions were explored at temperature of 333.15-353.15 K.The results of the study indicate that the absorption of EOCO₂ gas mixture decreases with increasing temperature,and the absorption reaches saturation when the time is 20 minutes.The content of EO in the exhaust gas of the absorption tower is less than 1000 ppm,under the conditions of EO content of 0.5 %,temperature of 60 ? and pressure of 2MPa.At the same time,the data in the absorption tower was compared with Aspen simulation data when the number of plates is 11,and the Murphy efficiency is 0.7,the experimental value was close to the simulated value.4.Simulation processes.The binary interaction parameters were applied to the purification of EO,when EC and water were used as absorbents by Aspen Plus,respectively.The simulation results show that the energy consumption of water used as an absorbent ws 19 % higher than ethylene carbonate in the traditional process at the same time,when EC was the absorbent,the solvent loss was less than 1 %,and the loss of water was 10 %.Compared with the traditional process,the energy consumption is reduced by 70 %,and the equipment is reduced by 3 sets,when EC was used as an absorbent,and EO absorption conversion to synthesize a new EC process was adopted.