【作者】 高元哲；

【导师】 李铭岫；

【作者基本信息】 河北师范大学 ， 无机化学， 2003， 硕士

【摘要】 甲基丙烯酸甲酯（MMA）是合成有机玻璃及MBS树脂的单体。我国MMA的生产以丙酮腈醇法（ACH法）占主导地位，合成路线复杂，生产工艺长，多步反应后产率低，成本高，其采用有剧毒的氢氰酸为原料，产生大量难于处理的废酸，所消耗的浓硫酸对设备腐蚀性大，对环境污染严重，因此开发新的MMA工艺路线很有必要。近年来很多国家采用异丁烯为原料来生产MMA并已实现工业化。异丁烯氧化酯化为甲基丙烯酸甲酯一般分三步完成：异丁烯先被氧化为甲基丙烯醛（MAL），MAL再氧化为甲基丙烯酸（MAA），最后加入甲醇酯化为MMA。日本旭化成公司以异丁烯为原料，得到MAL后直接氧化酯化的方法正在开发中。 本论文将异丁烯三步法制甲基丙烯酸甲酯简化为两段法，即把MAL氧化为MAA和酯化为MMA的反应合并为一步进行，将MAL溶于甲醇，再通入空气氧化、酯化。这是一种新的合成方法，催化剂的制备是本论文的技术关键。第一段反应的主催化剂为Mo-Bi或Mo-V复合氧化物，在其中添加稀土元素作为助催化剂。用共沉淀法制备了含有镧系元素Ln的Mo-Bi-Ln及Mo-V-Ln催化剂，并在固定床反应器中考查了反应温度、异丁烯浓度、原料气的流量及稀土添加量对异丁烯转化率和生成甲基丙烯醛的选择性的影响，制备了50种稀土钼-铋、钼-钒新型催化剂，筛选出了两种活性高的催化剂；并采用测定比表面、红外光谱、X-射线衍射、扫描电镜和拉曼光谱等技术对催化剂进行了表征。用共沉淀法制备的催化剂的活性主要决定于其化学组成，同时受到制备条件的影响，最佳催化剂的主要物相组成为α-Bi₂Mo₃O₁₂，Er₂Mo₃O₁₂和Mo₄V₆O₂₄，YbVO₄。另外还进行了反应机理的探讨，找出了催化剂的反应性能与结构的关系，为改进催化剂提供了理论依据。 第二段反应的主催化剂是Pd，添加Pb可提高选择性，当反应体系中水分含量低于3.5％时，可以防止催化剂活性降低，抑制副产物甲基丙烯酸的生成。主要研究了反应中原料的物质量的比、反应温度及催化剂的组成对原料的转化率和生成主产品选择性的影响。随着副产物分离技 河北师范大学硕士学位论文（摘要）术的发展，有望建立一条经济合理的工艺路线。在Pd中加入稀土来改变催化剂的组成和结构，调变催化剂的性能。在Pd5Pb，Fe，催化剂中添加Ln后既提高了MAL的转化率，又提高了生成MMA的选择性。 实验研究表明:在MO一Bi一O、MO一V-O催化剂中加入适量的稀土元素Ln，对原晶体结构起到一定的调变作用，有利于活性位点的活化和再生，可提高异丁烯转化率和生成甲基丙烯醛的选择性。MAL氧化酷化法采用一个工艺单元替代传统的两个工艺单元制取MMA，反应合并在同一容器中进行，可精简MAA的分离等步骤，缩短了工艺流程，使MMA收率从70%提高到了78.2%，达到国际先进水平，并且减少了对环境的污染，易于推广应用。因而，异丁烯两段法制MMA工艺具有较大的经济效益和社会效益，很有发展前景。更多还原

【Abstract】 Methyl methacrylate （MMA） is a monomer that is used to polymerize the organic glass and the MBS resin. MMA is produced by the method of acetone-cyanhydrin（ACH） mainly in our country. The synthetic route is complex, the technical line is long, and the yield is low with high cost after many steps. Hydrocyanic acid （seriously poisonous） is used as raw material, the treatment of numerous waste acid is difficult . Furthermore, concentrated sulfuric acid consumed in this method corrodes equipments and pollutes the environment seriously. Considering all of these, it is greatly necessary to develop a new chemical technology of MMA. Recently, in many countries isobutene is used as raw material to produce MMA and the method already is industrialized. The process of isobutene to be oxidized and esterified into methyl methacrylate is realized through three stages: First, isobutene is oxidized to methacrolein（MAL）.Then MAL is converted into methylacrylic acid （MAA） through oxidation. At last, MAA is esterified to MMA with methanol. In Japan, XuHuaCheng company uses isobutene as stock to get MAL, then acquires the product through direct oxidation and esterification. However, the technological process is being developed.This article simplifies the three-stage method described above to two-stage method. The method merges the oxidation and esterification into one step. That is to say, MAL is resolved in methanol, the air is inputed, in order for oxidation and esterification. This is a new synthetic method, and the preparation of catalyst is the key technique of this essay. In the first stage of reaction, the main catalyst is Mo-Bi or Mo-V mixed oxide, rare earth element is added as promoter. In the fixed bed reactor we checked some factors which can influence the conversion of isobutene and the selectivity of methacrolein. These factors include the temperature of the reaction, the concentration of isobutene , the flowing rate of raw material gas and the addition of rare earthelement. We’ve synthesized 50 kinds of new molybdenum-vanadium catalyst, characterized them, and selected 2 kinds of them with high activity. Furthermore, We’ve characterized them by means of measuring specific surface, Infrared spectrum, X-ray diffraction, Scanning electron microscope and Raman spectrum. The activity of catalyst prepared by coprecipitation is mainly decided by its chemical components, and it is influenced by the preparation conditions at the same time. The composition of main phase of the optimum catalyst is a -Bi₂Mo₃O₁₂, Er₂Mo₃O₁₂; Mo₄V₆O₂₄, YbVO₄). The reaction mechanism is discussed and the relation between the reaction and structure of catalyst is found, which can provide theoretical foundation for improving the catalyst.In the second stage, the main catalyst is palladium. Adding palladium to the catalyst can improve the selectivity of MMA. When the content of water in the reaction system is lower than 3.5 percent, it can prevent the reduction of catalyst’s activity and restrain production of the by-product-methacrylic acid. We mainly study some factors which influence the conversion of raw materials and the selectivity of the main product. Such factors include the molar ratio of raw materials, the temperature of the reaction and the composition of the catalyst. With the development of the separation technique of by-products, an economical technological route is hoped to be established. We added the rare earth so as to improve the composition and structure of the catalyst and adjust the performance of the catalyst. Adding Ln to the catalyst Pd₅Pb₁Fe₁ can improve not only the conversion of MAL, but also the selectivity of MMA.Experimental results indicate: adding suitable rare earth element Ln to Mo-Bi-O or Mo-V-O catalyst can adjust the previous crystal structure and it is advantageous to activate and regenerate the active sites. It can improve the conversion of isobutene and the selectivity of the production of methacrolein. Because this method substitutes the traditional two techno更多还原