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乙酸光氯化背包式反应精馏耦合工艺研究

Study on the Technology of Photochlorination of Acetic Acid in the Distillation Column with a Single Reactor

【作者】 陈桂平

【导师】 崔咪芬; 乔旭;

【作者基本信息】 南京工业大学 , 化学工程, 2003, 硕士

【摘要】 氯乙酸是一种及其重要的化工原料和有机中间体,目前氯乙酸主要以硫磺或醋酐为催化剂进行乙酸氯化生产而得。本文试图采用光为引发剂,开发出一条乙酸氯化生产氯乙酸的清洁工艺。由乙酸光氯化反应宏观动力学研究结果可见,反应速度相对较慢,且生成二氯乙酸副产品,为了乙酸光氯化工艺实现工业化,必须采用具有较大反应能力的反应与精馏耦合工艺。本文首次提出了将背包式反应精馏耦合技术应用于乙酸氯化反应的设想,通过对反应精馏耦合和反应精馏独立操作两种情况进行理论分析,发现反应精馏耦合在理论板数、能耗方面均具有明显优势,因而为背包式反应精馏应用于乙酸光氯化反应奠定了理论基础。本文建立了适合实验室研究的背包式光氯化反应精馏耦合装置,采用半连续操作的方法,在光引发条件下,考察了氯气流量、回流量和填料高度对乙酸光氯化反应的影响,得到了含量达90%以上的氯乙酸粗品,证实了工艺的可行性。实验结果还表明,在实验操作范围内,氯气流量对氯乙酸选择性影响显著,而影响分离能力的回流量和填料高度等条件基本能够满足抑制氯乙酸深度氯化的需要,要进一步提高氯乙酸的选择性,抑制乙酸直接氯化生成二氯乙酸的反应是必要的。在背包式反应精馏装置中,采用了外环流反应器,实验测定了该反应器中乙酸光氯化的反应动力学数据,采用平行-连串反应动力学模型进行了参数拟合,所得模型计算值和和实验值吻合较好。估计得到的动力学模型为:为扩大背包式反应精馏耦合工艺的应用范围,在所建立的实验装置上,进行了甲苯侧链光氯化反应的研究,结果表明工艺可行,可以得到含量96~98%的氯化苄粗品。

【Abstract】 Monochloroacetic acid (MCA) is a rather important chemical raw material and organic intermediate product, which is mainly manufactured by chloride of acetic acid using sulfur and anhydride acetic acid as catalyst. The effort has been made in this paper to exploit a clean technology of MCA preparation by chlorination of acetic acid, using light as the initiating agent.The result of study on the apparent kinetics of photochlorination of acetic acid showed that the reaction rate is comparatively slow and the byproduct of dichloroacetic acid (DCA) is created during the reaction. In order to put the technology of photochlorination of acetic acid into industrialization, the new technology about distillation column with a single reactor having a large reactive potency must be adapted. The presumption that new technology about distillation column with a single reactor can be used in photochlorination of acetic acid is first proposed in this paper. The fact that reaction distillation has obvious advantages in the number of theoretically perfect trays and energy consumption was obtained by theoretical analysis between the coupling of reaction and distillation and the independent operation, which lays a theoretical foundation on the application of the distillation column with a single reactor in photochlorination of acetic acid.The distillation column with a single photochlorination reactor was built in this paper, which is used in the laboratory study. In light initiation, the semi-continuous operation was applied to study the influence of the chlorine flow, the reflux and the height of the packing on photochlorination of acetic acid. Crude MCA with a purity of 90% or more was attained and the feasibility of this technology was proved. It was showed that the influence of the chlorine flow on the selectivity of MCA was notable and the conditions affecting the separate ability such as the reflux and the height of packing could meet the demand of the restraining of the over-chlorination of MCA in the experimental conditions. As a result, restraining direct chlorination of acetic acid to DCA is necessary to improve the selectivity of MCA.<WP=7>In the distillation column with a single reactor, the outer loop reactor is designed and applied. The reaction dynamics datas of photochlorination of acetic acid in the reactor were tested. According to parallel-consecutive reaction dynamics model, the parameters were fitted and the model result tallys experiment result well. The fitted dynamics model parameters are as following:In order to apply the reaction distillation technology in more fields, the methylbenzene side-chain photo-chlorination has been done in the experiment apparatus. The results have proven this technology is feasible and crude benzyl chloride with a purity of 96~98% can be obtained.

【关键词】 乙酸氯乙酸光氯化反应精馏动力学
【Key words】 acetic acidMCAphotochlorinationreaction distillationdynamics
  • 【分类号】TQ225
  • 【下载频次】174
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