【作者】 朱桂文；

【导师】 雷家珩；

【作者基本信息】 武汉理工大学 ， 应用化学， 2007， 硕士

【摘要】 邻溴苯甲腈的合成方法文献报道不多，这些制备方法都需要使用特殊的脱水剂或者催化剂，条件苛刻，反应步骤多，污染环境。在已见报道的邻溴甲苯氨氧化制邻溴苯甲腈专利中，反应温度过高，催化剂性能不稳定。本文研究了气相氨氧化法合成邻溴苯甲腈的方法，研制了较为适宜的催化剂，分析了各种外界因素对催化剂活性的影响，使氨氧化温度大大降低，并推测了反应机理。本文以邻溴甲苯的氨氧化为目标反应。研制了氨氧化反应的装置。研究了邻溴苯甲腈的合成和产物的分离、鉴定以及定性定量分析方法。对气相氨氧化法合成邻溴苯甲腈的多相催化剂进行了制备和评选。结果表明：选用VCrPMoO／SiO₂作为邻溴甲苯气相氨氧化催化剂，能够使反应顺利进行；当催化剂中各成分比例为：V∶Cr∶P∶Mo=1∶0.22∶0.97∶0.13时，催化剂具有较好的催化性能。在催化剂的活性评价中，对温度、进料配比以及空速等影响因素进行考察，得到的适宜反应条件是：温度360℃，各种进料的摩尔比为n（邻溴甲苯）：n（NH₃）∶n（air）∶n（H₂O）=1∶8∶30∶0.6，反应体积时空速为295h^-1，邻溴苯甲腈的产率可达77.9mol％。用比表面积和孔结构分析（BET）、傅立叶变换红外光谱（FTIR）、X射线衍射（XRD）、扫描电镜等表征手段对多组分负载型催化剂进行了表征。结果表明：（1）催化剂的比表面积不高，孔径和孔容较大；催化反应后的催化剂比表面、孔径和孔容都稍有增大。（2）催化剂活性组分在载体表面相互作用形成金属间氧化物，并高度分散，但并非成单分子层。（3）反应后的催化剂并没有明显的积碳。（4）反应过程中有活性物质的流失，这也是影响催化剂性能的主要因素。对邻溴甲苯气相氨氧化反应机理也进行了初步探讨，认为邻溴甲苯首先氧化生成邻溴苯甲醛中间体，然后在·NH₂自由基或H₂N_-的作用下生成邻溴苯甲腈。更多还原

【Abstract】 A few methods of preparing o-bromobenzonitrile not only have too many steps but also pollute the environment. The one and only patent about synthesis of o-bromobenzonitrile by ammoxidation of o-bromotuluene reported higher reaction temperature and unstable performance of catalyst. The preparation of catalyst for o-bromobenzonitrile ammoxidation from SiO₂ and mainly component of V-Cr-Mo-P was studied as well as mechanism of activation adsorption of NH₃ on the catalyst surface.It is the target reaction that to prepare o-bromobenzonitrile by gas phase ammoxidation of o-bromotuluene. During studying, the reaction device, the control system and the analysis system of the materials were developed. The method of isolation and the method of the qualitative and quantitative analysis of the reaction products were also studied.Ammoxidation of o-bromotuluene to o-bromobenzonitrile was studied over a large number of different catalysts. The results showed that （1） the ammoxidation reaction of o-bromotuluene to o-bromobenzonitrile can successfully proceed by using V-Cr-Mo-P-O/SiO₂ catalyst; （2） when V:Cr:P:Mo=1:0.22:0.97:0.13, the catalyst possess best performance.The effects of temperature, charge ratio of feeding and space velocity of feed gas on catalystic activity were detected. The results showed that the optimal reaction temperature is 360℃, the optimal space velocity of the feed gas is 295h^-1, n（o-bromotuluene）:n（NH₃）:n（air）:n（H₂O）=1:8:30:0.6, the mole yield of o-bromobenzonitrile is 77.9%.The catalysts were characterized by means of specific surface and pore structure（BET）, FTIR, XRD and SEM. The results showed that （1） The activity of the catalysts is associated with their specific surface area and pore volume. The specific surface area of the catalyst is low and the pore volume is high, the surface area and pore volume of used catalys increased little. （2） The species of the active component interact to form interoxide and highly dispersed but not monolayer on the surface of catalyst. （3） The carbon build-up on catalyst is not obvious. （4） The active components run off from the catalysts during the reaction, which is the prime reason to decrease activity.更多还原