二甲醚经低碳烯烃合成汽油组分正辛烷、对二甲苯热力学分析

Thermodynamic analysis for DME conversion to n-octane and p-xylene of gasoline via light olefins

采用原子矩阵法确定了二甲醚经低碳烯烃制正辛烷和对二甲苯的独立反应数,并通过建立平衡关系,采用文献介绍方法,计算了各个反应的反应热、平衡常数及反应平衡时的平衡组分浓度。经分析表明,反应属放热反应;模型中绝大多数反应能自发进行,并且平衡转化率较高;低温高压有利于正辛烷的生成,而低温低压有利于对二甲苯的生成;丙烯生成正辛烷和对二甲苯的转化率远高于乙烯和丁烯,因此控制中间产物丙烯的含量有利于控制目的产物的产出。

The number of independent reactions of dimethyl ether （DME） to n-octane and p-xylene via light olefins was obtained by atomic matrix method. Reactions heat, equilibrium constants, equilibrium relationships among the produets of all those reactions were calculated through building equilibrium relationships with the methods from literatures. The results show that most of the reac- tions are exothermic reactions. Most of the reactions in models could proceed spontaneously with high equilibrium conversion. Low temperature and high pressure are beneficial to improve the yield of n-octane, but low temperature and low pressure are beneficial to improve the yield of p-xylene; conversion rates of propylene to n-octane and p-xylene were higher than that to ethane and butylene. The product yield could be improved through controlling the content of propylene.