【作者】 尹玲玲；

【导师】 刘少文；

【作者基本信息】 武汉工程大学 ， 化学工艺， 2011， 硕士

【摘要】 间-苯二胺是一种重要的有机化工原料和中间体,具有多种用途。除了用于合成偶氮染料、毛皮染料、活性染料和硫化染料的中间体,还可用于制造媒染剂、染发剂、橡胶配合剂等,因此具有较好的应用前景。相比于传统的铁粉还原,催化加氢法制备间-苯二胺由于具有收率高,产品质量好,环境友好等优点而备受关注。目前传统的间二硝基苯加氢反应装置是泥浆流搅拌反应器,其转化率和选择性虽然能达到90%以上,但存在催化剂与产物分离困难、催化剂易磨损以及生产只能间歇操作等缺点。滴流床反应器虽然能克服上述缺点,但因采用的催化剂颗粒较大,扩散阻力分布不均匀,因此反应的选择性不高,且床层阻力较大。以堇青石蜂窝陶瓷为载体的结构化催化剂因床层压降小、传质效率高和放大效应小等优点,逐渐受到关注。用于催化加氢的催化剂主要有贵金属催化剂、骨架镍催化剂以及负载型镍基催化剂,其中贵金属催化剂活性较高,但价格昂贵,骨架镍催化剂由于不能回收重复利用而存在一定的环境污染,因此负载型镍基催化剂受到关注。但镍基催化剂由于活性组分与Al₂O₃载体形成NiAl₂O₄尖晶石物相,使催化剂活性不高。有相关文献报道助剂的引入可以改善镍基催化剂的性能,但原因尚不清楚。研究和开发对间-二硝基苯加氢反应具有高活性、高选择性的负载型镍基结构化催化剂是本课题的研究重点。本论文采用结构化反应装置研究了结构化镍基催化剂对间-二硝基苯加氢合成间-苯二胺反应的反应性能,研究了温度、压力、反应物浓度、催化剂用量等因素对间二硝基苯加氢反应的影响,助剂和制备方法对催化剂反应性能的影响规律,并利用BET、TPR、XRD、TEM和活性评价对镍基结构化催化剂物化性质进行了表征,结果表明,Ni负载量为5wt%时,催化反应活性最佳,随着Ni含量增加,反应转化率与选择性逐渐下降;添加一定量的助剂La有利于提高加氢反应的活性与选择性,TPR表征结果显示La助剂的引入提高了催化剂的还原性能。间-二硝基苯加氢反应工艺条件得到进一步优化,反应压力为3Mpa,温度为363K,溶剂比为4:1,氢气流量为100ml/min,液体流量为5ml/h时,催化剂活性较好,转化率最高为83.5%,选择性为90.2%。本实验研究所得出的反应结果对于今后结构化催化反应器在催化加氢合成领域中的进一步应用提供了有益信息。更多还原

【Abstract】 m-Phenylenediamine is an important organic intermediate for the synthesis of some polymers, dyestuff and other materials. With the increasing application of engineering materials, especially aromatic polyamide fibers and polyurethane, the demand for MPD is growing. Compared with the iron-acid reduction method, the catalytic hydrogenation of MDNB in liquid phase is an attractive process due to its advantages, such as high product yield, mild reaction conditions, less pollution to the environment, and so on.Recently, the relatively mature reactor for hydrogenation is the stainless steel autoclave equipped with a magnetically driven agitator reactor. The conversion of MDNB and the selectivity of MPD can reach 90%, but the catalytic system has some shortcomings, such as, difficulty to separate the catalyst and the reactants, intermittent operation, the low rate of total production; Another kind of trickle-bed reactor is able to maintain continuous production, but because its use is still the catalyst particles, resulting in a larger concentration of poor, low selectivity. In recent years, the cordierite structured catalysts has caused the gas-liquid-solid reaction more and more attention for the parallel vertical channels with a regular, low pressure drop, high efficiency catalyst and a better effect of heat and mass transfer characteristics and easy to replace.Raney nickel and supported noble metals（such as Pd、Pt） are usually used as hydrogenation catalysts. However, the rather rare occurrence and high price of noble metals restrict their application. As to Raney nickel, the severe corrosion and pollution resulted from its preparation process, and the safety problem during its storage and application make its use less attractive. Recently, It is well known that the supported nickel catalyst is the most important catalyst for its cost and excellent hydrogenation properties, whereas the active component nickel usually combines with support Al₂O₃ easily and forms NiAl₂O₄ of spinel structure, deactivating the catalyst. Thus, the development of new catalysts is really essential. Although some reports have ever expressed that the La₂O₃ is an ideal promoter for hydrogenation process, the modified mechanism of La for nickel catalyst is still incompletely known. In this thesis,the structured nickel catalysts have been used for the hydrogenation of m-Dinitrobenzene in order to develop a catalyst with high activity, selectivity and long service life.The catalytic hydrogenation of m-dinitrobenzene （MDNB） to m-phenylenediamine （MPD） was tested over Ni-La/γ-Al₂O₃/cordierite structured catalyst in a structured reactor. Effects of the reaction conditions, such as temperature, pressure, space velocity of hydrogen and MDNB, and catalyst dosage on the catalyst were systematically investigated. Based on the experimental results of BET, TPR, XRD, TEM, XPS and activity evaluation, the additives and catalytic performance of the catalyst were investigated. The results show that when w（Ni） =5wt%, the activity was the best. The activity and the selectivity of the samples decreased with the increase in nickel content. Adding a certain amount of additives La could improve the activity and selectivity of hydrogenation reaction, TPR characterization results the introduction of La additives improve the reduction of the catalyst performance. For Hydrogenation reaction conditions were further optimized, the reaction pressure is 3Mpa, temperature 363K, the solvent ratio of 4:1, the hydrogen flow rate of 100ml/min, liquid flow rate of 5ml/h, the catalyst activity is better. The maximum conversion rate of 83.5% and the selectivity was 90.2%.The experimental research results obtained for the future structure of the reaction of catalytic hydrogenation in the catalytic reactor for further applications in the field of useful information.更多还原