甲醇芳构化反应的热力学研究

Study on thermodynamics of methanol to aromatic reaction

基于双循环机理描述的反应网络,研究了甲醇芳构化反应(MTA)的热力学变化规律以及双循环之间的相互影响,并根据最小Gibbs自由能法,采用GAMS软件计算得到不同条件下产物的热力学平衡组成。热力学计算结果表明:对于烯基循环,低温有利于产物向碳链增长的方向移动,促进芳基循环,高碳烯烃更易裂解产生丙烯;对于芳基循环,高温不利于重芳烃的生成;MTA反应中苯、甲苯和二甲苯(BTX)平衡组成的理论值为49.23%(干基质量分数);若弱化烯烃中间物生成烷烃的反应,BTX平衡组成在450℃时可达97.60%。

The transformational rules of thermodynamics of the methanol to aromatic （MTA） reaction and the interplay of the dual cycles were studied on the basis of reaction network described by a dual - cycle mechanism. The thermodynamic equilibrium compositions of products on different conditions were calculated by GAMS software and the minimum Gibbs free energy method. The thermodynamic calculation results showed that for olefin - based cycle, the low temperature favored the growth of olefins carbon chain and the increasing of the propagation of the aromatic -based cycle, and the higher olefins easily and spontaneously cracked to propylene. For aromatic -based cycle, the high temperature was unfavorable to the generation of heavy aromatics. The theoretical equilibrium composition of benzene, toluene,xylenes （BTX） was 49.23 % （ mass fraction of dry basis） in MTA reaction. And if the reaction of olefin intermediates to alkanes was weakened, the equilibrium composition of BTX could reach up to 97.60% at 450 ℃.