摘要
均三甲苯是一种重要的化工原料,通常存在于重整重芳烃中,其中均三甲苯与偏三甲苯、邻甲乙苯的分离较为困难。测定了2 kPa下均三甲苯(1)-偏三甲苯(2)、均三甲苯(1)-邻甲乙苯(3)两个体系的汽液相平衡数据,并分别采用NRTL和UNIQUAC活度系数模型对相平衡数据进行关联,回归获得二元交互参数,并进行了热力学一致性检验。结果表明,在2 kPa下,均三甲苯与邻甲乙苯无法通过普通精馏实现分离。通过对均三甲苯-偏三甲苯-邻甲乙苯体系进行烷基化反应,而后分别采用单塔减压精馏和双塔减压精馏对反应产物的分离进行精馏模拟,得出较优工艺为双塔连续减压精馏,两塔塔板数分别为50,回流比分别为7和8,此时均三甲苯纯度可达98%(质量)。该研究不仅补充了汽液相平衡数据库,也为低压下C9体系的分离工艺设计提供参考。
1,3,5-trimethylbenzene is an important chemical raw material and usually exists in reformed heavy aromatics.It is difficult to separate 1,3,5-trimethylbenzene from 1,2,4-trimethylbenzene and 2-ethyltoluene in the C9 aromatics mixture.The vapor-liquid equilibrium(VLE)data of 1,3,5-trimethylbenzene(1)-1,2,4-trimethylbenzene(2)and 1,3,5-trimethylbenzene(1)-2-ethyltoluene(3)were measured at 2 kPa and then correlated by the activity coefficient models NRTL and UNIQUAC.The binary interaction parameters were obtained through regression.The thermodynamic consistency was checked as well.The results showed that 1,3,5-trimethylbenzene and 2-ethyltoluene could hardly be separated at 2 kPa by ordinary distillation.After the alkylation reaction of the ternary system(1,3,5-trimethylbenzene-1,2,4-trimethylbenzene-2-ethyltoluene),single column and double-column distillation processes at low pressure were used to separate the reaction products by simulation,respectively.Compared to the single-column distillation process,the double-column one presented a better separation performance.The suitable separation parameters were obtained as follows:the number of stages in both columns was 50,and the reflux ratios were 7 and 8 respectively.The purity of 1,3,5-trimethylbenzene could reach 98%(mass)accordingly.This study not only fills in VLE database,but also provides a feasible method for the separation of C9 aromatics at low pressure.
作者
徐健元
吴艳阳
徐菊美
彭阳峰
XU Jianyuan;WU Yanyang;XU Jumei;PENG Yangfeng(College of Chemical Engineering,East China University of Science and Technology,Shanghai 200237,China)
出处
《化工学报》
EI
CAS
CSCD
北大核心
2021年第9期4504-4510,共7页
CIESC Journal
关键词
三甲苯
汽液平衡
分离
活度系数
流程模拟
trimethylbenzene
vapor-liquid equilibria
separation
activity coefficient
process simulation
