【作者】 王声洁；

【导师】 沈本贤；

【作者基本信息】 华东理工大学 ， 化学工艺， 2010， 博士

【摘要】 氯乙烯单体(VCM)主要用来合成聚氯乙烯。而聚氯乙烯(PVC)是世界五大工程塑料之一,在各行各业具有十分广泛的应用。目前氯乙烯单体的工业合成方法主要有乙炔氢氯化法和乙烯氧氯化法。在我国,大约70%氯乙烯单体采用乙炔氢氯化法生产。这是由我国的特殊能源结构所决定的。我国石油资源短缺,相对丰富的煤炭资源为乙炔氢氯化法提供充足的乙炔原料。然而,该工艺路线一直采用剧毒的氯化汞／活性炭为催化剂,该催化剂易挥发流失,对工人健康及当地环境造成了严重的危害。如何消除汞触媒污染,实现乙炔氢氯化合成氯乙烯清洁工艺路线,是摆在化学工艺工作者面前关于氯碱行业的亟待解决的问题。本论文以绿色催化工艺的开发为导向,以高效非汞触媒的开发为重点,结合多种表征及模拟手段,开发了基于非汞催化剂的乙炔氢氯化反应合成氯乙烯单体的绿色催化工艺。通过对多种金属元素催化乙炔氢氯化反应的活性进行考察,筛选出活性相对较好的三种活性组分PdCl2, CuCl2和AuCl3。以此三种活性组分为研究重点,详细研究了不同反应条件下单组分PdCl2, CuCl2和AuCl3催化剂的催化性能和失活原因。结果发现,单组份催化剂的催化性能均不能满足实际生产的要求。通过对上述三组分的复配和活性考察发现氯化金和氯化铜之间存在显著的协同作用,双组份AuCl3-CuCl2催化剂相比单金属催化活性及稳定性显著改善。优选活性炭为载体,Au/Cu=1:6,成功合成了具有良好活性,选择性和稳定性的双组份AuCl3-CuCl2/C催化剂,并借助高等仪器分析对双组份AuCl3-CuCl2催化剂的微观性质进行了表征分析。对乙炔氢氯化反应进行了热力学分析,考察了该反应的可行性及反应平衡所能达到的最高转化率,然后以热力学计算结果为参考,考察了双组份AuCl3-CuCl2/C催化剂在不同反应温度、不同配比、不同空速和不同反应气氛下的反应行为,得出了双组份AuCl3-CuCl2/C催化剂的优化反应条件,即：温度140～170℃,氯化氢和乙炔配比应在1.15左右,总空速应在100-150h-1。采用密度泛函理论方法研究了乙炔氢氯化反应在非汞催化剂上的催化反应机理。通过模拟计算得到反应路径上的反应物、过渡态、中间体和产物的优化几何构型,提出了可能的乙炔氢氯化反应路径。通过分子轨道计算,研究了双组份催化剂中氯化铜和氯化金之间的作用机理。在固定床积分反应器中研究了双组份AuCl3-CuCl2/C非汞催化剂催化乙炔氢氯化反应合成氯乙烯的反应动力学。首先基于DFT模拟结果,假设反应机理遵循Eley-Rideal模型,采用Langmuir吸附等温线方程,推导出动力学方程式。然后在消除内外扩散的情况下,考察了不同温度下,转化率随空速的变化。最后,通过计算机拟合得出了乙炔氢氯化反应的本征动力学方程。实验数据与机理方程基本吻合,进一步验证了假设机理的合理性。基于实验得到的动力学方程,采用二维拟均相模型对基于非汞催化剂的乙炔氢氯化反应实验室固定床反应器进行了模拟计算,考察了床层内浓度分布、温度分布。论文还详细考察了双组份AuCl3-CuCl2/C非汞催化剂对不同反应条件的扰动的稳定性,并在优化的反应条件下考察了催化剂的寿命。结果表明：温度在150～180℃范围内,空速在120-480h-1的范围内调变对双组份AuCl3-CuCl2/C非汞催化剂稳定性无明显影响,而原料配比及乙炔气的纯度变化对催化剂的稳定性影响显著。在T=160℃, P=0.1 MPa, GHSV=110h-1, C2H2/HCl=1:1.15的反应条件下,催化剂寿命大于1200h。另外,对使用1200h后的催化剂,在大空速下(3000h-1)进行了加速失活实验,通过失活前后的催化剂表征分析,详细探究了催化剂的失活原因,并提出了可行的再生方法。最后,对非汞催化剂催化乙炔氢氯化反应制氯乙烯的生产成本进行了估算和分析。更多还原

【Abstract】 Vinyl chloride monomer (VCM) is mainly used for synthesis of polyvinyl chloride (PVC), one of the five engineering plastics, which is widely used in all walks of life. Currently, there are mainly two synthesis methods for vinyl chloride monomer, which are acetylene hydrochlorination and ethylene oxychlorination. In our country, about 70% of vinyl chloride monomer products are produced from the acetylene hydrochlorination. This is determined by our special energy structure. In China, petroleum resources are scarce, while coal resources are relatively rich, which provide adequate acetylene materials for the acetylene hydrochlorination. However, poisonous activated carbon supported HgCl2 catalyst has been used in this process. The toxicity and volatility of the catalyst causes serious damage to the workers and environment. It is a great challenge for the whole chlor-alkali industry to eliminate or reduce the pollution caused by the catalyst.In this paper, our research is oriented with the development of a green catalytic process, aiming to develop an efficient non-mercury catalyst. Combining with various characterization and simulation calculation methods, a green catalytic process of the acetylene hydrochlorination based on non-mercury catalyst to produce vinyl chloride monomer is developed successfully.PdCl2, CuCl2 and AuCl3 are discovered to be active to the acetylene hydrochlorination. Catalytic performance and deactivation of monocomponent PdCl2, CuCl2 and AuCl3 catalysts are studied in detail using several characterization methods. The results showed that monocomponent catalysts are not favorable for the catalytic acetylene hydrochlorination reaction. With the aim to improve the catalytic performance, two-component catalysts of PdCl2-CuCl2/C, PdCl2-AuCl3/C and AuCl3-CuCl2/C are prepared and their activities for the acetylene hydrochlorination are investigated. It was indicated that activated carbon supported AuCl3-CuCl2 catalyst with Au/Cu=1:6 is not only highly active but also fairly stable. Its microscopic property is characterized using several analysis methods.The thermodynamics of acetylene hydrochlorination was studied. The thermodynamic characteristics the acetylene hydrochlorination were discussed. The equilibrium conversion and favorable reaction temperature were obtained. On the basis of the results of thermodynamics calculation, the catalytic performance of AuCl3-CuCl2/C catalyst under various temperatures, feed ratios, space velocities and reation atmospheres were investigated in detail. The optimized reaction conditions were obtained: temperature is no less than 140-170℃, feed ratio of HCl/C2H2 is around 1.15, total gas hourly space velocity is in the range of 100-150h-1.The mechanism of the acetylene hydrochlorination was explored using the DFT theoretical calculation. The optimized strucutures of reactants, transition complexes, intermediate products and products were obtained and the possible reaction mechamism was proposed. Moreover, the interation between CuCl2 and AuCl3 was explored by the calculation of molecular orbital.Kinetic model of the acetylene hydrochlorination based on the AuCl3-CUCl2/C catalyst was studied in a fixed-bed integral reactor. On the basis of the results of DFT theoretical calculation, the acetylene hydrochlorination was proposed to follow the Eley-Rideal reaction mechanism mode. The kinetics equation was derived based on the Langmuir adsorption model. After the internal and external diffusion were eliminated, the change of conversion with the space velocity under different reaction temperature point was investigated. The reaction kinetic equation was finally obtained by fitting kinetic data. The acetylene hydrochlorination in a fixed-bed microreactor was simulated using Pseudo-homogeneous modal and the distribution of concentration and temperature were investigated.The stability of AuCl3-CUCl2/C catalyst under various condition disturbances were studied in detail. The life of AuCl3-CUCl2/C catalyst was tested under the optimized reaction conditions. The results obtained indicated that the AuCl3-CUCl2/C catalyst was stable with the disturbance of temperature (15-180℃) and space velocity (120-480h"1), but sensitive to feed ratio of HCl/C2H2 and the purity of acetylene. Under the reaction conditions of T=160℃, P=0.1 MPa, GHSV=110h"1, C2H2/HC1=1:1.15, the life of the catalyst is more than 1200h. After 1200h reaction, further deactivation test under a big space velocity (3000h-1) was carried out. The deactivation and regeneration of AuCl3-CuCl2/C catalyst was studied in detail and a practical regeneration method was proposed. In the end, the cost of the acetylene hydrochlorination based on the AuCl3-CUCl2/C catalyst was evaluated.更多还原