【作者】 张婷婷；

【导师】 蒋景阳；

【作者基本信息】 大连理工大学 ， 有机化学， 2016， 博士

【摘要】 对氨基苯酚是合成对乙酰氨基酚的重要中间体。由Pt催化的硝基苯加氢制备对氨基苯酚工艺因其原料成本低和产品质量高等特点,被普遍认为是目前最有前景的对氨基苯酚制备工艺。该工艺采用硫酸提供中间体苯基羟胺重排生成产物所需的酸性,在后处理过程中需要加碱中和从而产生大量的含盐废水。本论文着眼于对氨基苯酚的绿色制备工艺,探索了使用加压CO2/H2O体系中原位形成的碳酸替代硫酸为硝基苯制备对氨基苯酚提供酸性,反应结束后释放CO2,体系可自中和,有效避免了含盐废水的生成,所得对氨基苯酚的选择性与其它替代硫酸的体系效果相当,为67%。为了进一步避免向反应液中加入非绿色添加剂,论文尝试将Pt-Co催化剂应用于加压CO2/H2O体系中的该反应,所得产物选择性与使用添加剂修饰了的Pt/C催化剂效果相当,为67%。论文首次将Pt-Sn双金属催化剂应用于加压CO2/H2O体系中的硝基苯加氢制备对氨基苯酚。在优化后的条件下,Pt-Sn/y-Al2O3催化所得产物选择性可达到与传统工艺中使用硫酸和非绿色添加剂所得的效果相当,为85%。论文进一步将Pt-Pb双金属催化剂应用于加压CO2/H2O体系中的硝基苯加氢制备对氨基苯酚,在对催化剂制备参数和反应条件进行了详细优化后,催化剂Pt-Pb/SiO2所得产物选择性为82%。论文还研究了将复合载体负载的Pt-M(M:Sn, Pb)催化剂和Pt基多元金属催化剂分别应用于加压CO2/H2O体系中的硝基苯加氢制备对氨基苯酚,由ZSM-5和TiO2-C分别负载的双金属Pt-Sn(或Pt-Pb)催化剂能够有效促进产物的选择性生成,多元金属Pt-Sn-Pb/SiO2催化剂在优化后的反应条件下,产物选择性也可达到82%。更多还原

【Abstract】 p-aminophenol (PAP) is of great importance as an intermediate for the synthesis of paracetamol. PAP’s preparation by Pt-catalyzed hydrogenation of nitrobenzene (NB) has gained attention owing to its low cost of raw material and high product quality. Usually sulfuric acid was used for the rearrangement of the intermediate phenylhydroxylamine to PAP in this reaction, but a neutralization step was inevitably needed to separate PAP from the reaction mixture, during which a large volume of effluents was generated. In this thesis, aiming to develop a green preparation method of PAP, the self-neutralizable carbonic acid formed in pressurized CO2/H2O system was used as an alternative to sulfuric acid in this reaction, and the selectivity of PAP was 67%. Usually dimethylsulfoxide (DMSO) was used to modify the Pt catalyst for higher selectivity of PAP, but it was environmentally undesirable. Pt-Co catalyst was employed in the hydrogenation of NB in pressurized CO2/H2O system without any additives, and the selectivity of PAP could reach 67%, which was comparative with the selectivity when Pt/C and DMSO were used.Pt-Sn catalyst was firstly applied in the hydrogenation of NB in pressurized CO2/H2O system. By employing Pt-Sn/γ-Al2O3 as catalyst, the selectivity of PAP could be 85%, which was comparative with that obtained by the conventional method using sulfuric acid and additives.The catalytic performance of Pt-Pb catalysts on the hydrogenation of NB in pressurized CO2/H2O system has been studied. Pt-Pb/SiO2 catalyst turned out to be effective for the selective formation of PAP, and the selectivity as high as 82%was obtained.Pt-M (M=Sn or Pb) catalysts with several different compsite supports and Pt-based multiple metal catalysts were also investigated for the selective conversion of NB to PAP, respectiviely. ZSM-5 or TiO2-C supported Pt-M catalysts was favorable for the selectivie formation of PAP. As for the Pt-Sn-Pb/SiO2 catalyst, PAP’s selectivity of 82% was achieved under the optimized reaction conditons.更多还原