乙二醇与甲醇脱水的非均相热力学平衡分析

Heterogeneous Thermodynamic Equilibrium Analysis of the Dehydration of Ethylene Glycol With Methanol to Ethylene Glycol Methyl Ether

煤化工行业发展快速形势下的乙二醇和甲醇产能过剩,使二者分子间脱水制乙二醇甲醚的研究成为热点。本文基于吉布斯自由能最小化原理,采用改进后的遗传算法,对乙二醇和甲醇的非均相脱水过程进行了热力学平衡计算。在乙二醇进料100 mol,温度20~300℃,压力0.1~0.7 MPa,甲醇与乙二醇进料物质的量比为1∶2~6∶1的条件下,考察了温度、压力、进料物质的量比对反应物平衡转化率、产物选择性以及气液相平衡组成的影响。计算结果表明:在0.3 MPa、进料物质的量比3∶1的条件下,60~120℃内的气液相共存区间,乙二醇的转化率和乙二醇二甲醚的选择性最高,为99.99%和99.97%;增加压力会影响转化率和选择性发生变化的温度区间,整体趋势没有明显变化;增加进料物质的量比使乙二醇的转化率增加,最高接近100%,提高了乙二醇二甲醚选择性,非均相区间的温度范围由40℃收窄至20℃。

The problem of excess production capacity of ethylene glycol and methanol in condition of the rapid development of the coal chemical industry,made the dehydration conversion of the two into ethylene glycol methyl ether become a research hotspot.The thermodynamic equilibrium calculations for the heterogeneous dehydration process of ethylene glycol and methanol were optimized based on the Gibbs free energy minimization principle using a modified genetic algorithm in the manuscript.Under the conditions of ethylene glycol feed of 100 mol,20-300℃,0.1-0.7 MPa,and the feed amount of substance ratio of methanol to ethylene glycol is 1∶2-6∶1,the effects of temperature,pressure,and feed amount of substance ratio on the equilibrium conversion of reactants,product selectivity,and gas-liquid phase equilibrium composition were examined.The results show that under the conditions of 0.3 MPa and feed amount of substance ratio of 3∶1,within the gas-liquid coexistence range of 60-120℃,the highest conversion of ethylene glycol and selectivity of ethylene glycol dimethyl ether are 99.99%and 99.97%,respectively.Increasing pressure affects the temperature range in which conversion and selectivity change,but the overall trend remains unchanged.Increasing the feed amount of substance ratio increases the conversion of ethylene glycol to near 100%and improves the selectivity of ethylene glycol dimethyl ether,and narrowes the temperature range of the heterogeneous range from 40℃to 20℃.