Abstract:

For the efficient and eco-friendly preparation of trichloroethylene (TCE) and perchloroethylene (PCE), as well as the application of byproduct HCl, a process composed of a two-stage series reaction was firstly proposed using HCl as the chlorine source. Oxidation of HCl to Cl₂ was carried out in the first stage of the process, and the second stage of the process was the oxychlorination of EDC with generated Cl₂ and unreacted O₂ in the first stage to TCE and PCE. These reactions were carried out in series so that the deep oxidation reactions were effectively avoided. In addition, by using the two-stage process, different catalysts and process parameters could be applied in each stage to meet the different reaction needs. The complex Ce-Cu-K/Y catalyst was used in the first stage, and it was applied in the second stage with optimized loading of the active component. The appropriate loadings of K/Cu (mass ratio) and the active component were 0.73 and 45.5%, respectively. Meanwhile, the operation conditions in the second stage of the process were optimized. 83.4% yield of both TCE and PCE, 96.1% yield of organochloride could be obtained at 430℃ with 0.5 h^-1 weight hourly space velocity (WHSV) of EDC, molar ratio of O₂ to EDC 1.8, and molar ratio of O₂ to EDC 2.4. The results presented an encouraging prospect in industrial application.

Key words: oxychlorination, trichloroethylene, perchloroethylene, fluidized-bed, Y-molecular sieves, two-stage reactions

摘要：

为高效、环保地生产三、四氯乙烯,同时解决副产氯化氢的出路问题,通过对二氯乙烷氧氯化制三、四氯乙烯反应体系的剖析,提出以氯化氢为氯源的两段反应串联新工艺。在第1段中仅仅发生氯化氢氧化反应,第2段中二氯乙烷与生成的氯气及未反应完的氧气发生一系列氧氯化反应制三、四氯乙烯。该工艺有效避免了二氯乙烷及其他有机氯的深度氧化;而且采用该工艺,每一段可采用不同的催化剂和不同的反应条件,以适应不同的反应需求。第2段采用的催化剂是在第1段采用的负载于Y分子筛的Ce-Cu-K复合催化剂基础上改性优化而成,适宜的钾铜质量比为0.73;当催化剂活性组分负载量达到45.5%时,三、四氯乙烯收率最优。同时对第2段反应条件进行了优化,结果表明适宜的工艺条件为:反应温度430℃,二氯乙烷重时空速0.5 h^-1,二氯乙烷、氯化氢与氧气三者的进料摩尔比1:2.4:1.8;此时三、四氯乙烯收率最高可达83.4%,有机氯的总收率可达96.1%。反应结果较单段氧氯化反应工艺显著提升,具有良好的工业应用前景。

关键词: 氧氯化, 三氯乙烯, 四氯乙烯, 流化床, Y分子筛, 两段反应