加氢催化对硝基苯酚催化剂的设计和制备

发布时间：2018-06-10 05:23

  本文选题：对氨基苯酚 + 加氢催化　； 参考：《天津工业大学》2017年硕士论文

【摘要】：苯胺类化合物是一类重要的有机化工中间体,广泛应用于燃料、医药、杀虫剂和显影剂等精细化工品的合成。目前工业上制取苯胺类化合物的主要方法是以相应的硝基苯类化合物为原料,通过催化剂将硝基加氢还原为氨基来制备。其中,对硝基苯酚(4-NP)还原制备对氨基苯酚(4-AP)就是一个重要的代表性反应。目前,这类反应的高效催化剂主要是贵金属材料。针对贵金属的稀缺与高成本,为了提高贵金属催化剂的利用率以及催化活性,本文主要制备了两类负载型的贵金属类催化剂,并研究它们在这个反应中的催化性能,具体内容如下:1.以γ-Fe_2O_3为核,包覆水热碳构成核/壳结构的载体材料,再通过水热碳层的吸附作用,吸附Pt离子,在不同温度下对其进行高温焙烧制备一系列的Fe_2O_3@C-Pt-T催化剂。制备得到3-4 μm的壳/核结构微球,外层水热碳大约50-60 nm厚。通过SEM,TEM,XRD,EDX,ICP,XPS等表征手段对催化剂进行表征和催化性能测试。实验结果证明,在600℃焙烧的催化剂催化性能最高,能够在6 min内将溶液中的底物完全反应。在催化剂的整体结构中,y-Fe_2O_3核赋予催化剂磁性,因此在催化剂的回收时,仅需要施加一个额外的磁场,就可以简单快速并且高回收率的将催化剂从反应体系中回收,而水热碳层赋予催化剂的吸附性,不仅在负载Pt颗粒时可以吸附Pt~(4+),而且可以在催化过程中吸附反应底物,进一步提高了催化剂的催化性能。外层负载的Pt颗粒是催化剂的催化活性中心,小尺寸,高分散性的Pt颗粒不仅提高了贵金属的利用率,降低了成本,还进一步提高了催化剂的催化性能。该催化剂还具有非常好的循环稳定性,在循环反应十次之后其催化性能未见明显衰减。2.首先以低温水热法合成了具有完美棒状结构的ZnO纳米材料,并用作催化剂的载体材料,利用ZnO的光响应特性,在紫外光的诱导下,在ZnO表面氧化PtCl_4~(2-)离子为PtO_2,并且沉积在ZnO纳米棒表面,合成PtO_2/Zn0催化剂。通过对紫外光照时间不同的控制,制备一系列PtC_2/ZnO-t催化剂。通过SEM,TEM,XRD,EDX,ICP,XPS等表征手段和催化性能测试后,实验结果表明,在紫外光下照射30 min的PtO2/ZnO-30催化性能最高,而且紫外诱导法合成PtO_2催化剂相比传统湿法制备的催化剂催化性能提高了2.3倍,而且与相对应的Pt单质催化剂对比,催化性能也提高了6倍。该催化剂还具有非常好的循环稳定性,在循环使用十次之后其催化性能未见明显衰减。作为一种简单绿色高效的合成方法,紫外诱导法体现了其独特的优越性以及未来工业生产的巨大应用潜力。
[Abstract]:Aniline compounds are a kind of important organic chemical intermediates, which are widely used in the synthesis of fine chemicals such as fuel, medicine, insecticide and developer. At present, the main method of preparing aniline compounds in industry is to prepare nitrobenzene compounds by hydrogenation of nitro compounds to amino groups by using the corresponding nitrobenzene compounds as raw materials. The preparation of p-aminophenol 4-APs by reduction of p-nitrophenol 4-NPs is an important representative reaction. At present, the main catalysts for this kind of reactions are precious metal materials. In view of the scarcity and high cost of precious metals, in order to improve the utilization and catalytic activity of noble metal catalysts, two kinds of supported noble metal catalysts were prepared and their catalytic properties in this reaction were studied. The details are as follows: 1. Using 纬 -Fe _ 2O _ 3 as core and coated with hydrothermal carbon to form a core / shell structure carrier material, Pt ion was adsorbed by hydrothermal carbon layer and calcined at different temperatures to prepare a series of Fe2O3C-Pt-T catalysts. Shell / core microspheres of 3-4 渭 m were prepared, and the outer hydrothermal carbon was about 50-60 nm thick. The catalyst was characterized and its catalytic performance was tested by means of SEMMA-TEMX / XRDX EDX / ICP / XPS and so on. The results show that the catalyst calcined at 600 鈩，

本文编号：2002113