Research On Green Process Of Hydroalkylation Using Noble Metal Catalysts

With the improvement of the quality requirements of the products produced in the chemical industry and the emphasis on environmental protection,the development of a process route that can ensure the high quality of products and meet the requirements of environmental protection has become the focus of research.In this paper,the synthesis of 3-amino-n-ethyl carbazole,a dye intermediate,and cyclohexylbenzene,a fine chemical product,are taken as specific cases to introduce a new green process.Main research findings have been summarized as following:Chapter 1:This chapter introduces the basic properties,applications and synthesis methods of 3-amino-n-ethyl carbazole and cyclohexylbenzene,two important fine chemical intermediates.In this paper,many problems existing in the traditional process are summarized,and the synthesis process of 3-amino-n-ethyl carbazole is improved from two aspects of reforming the traditional process and developing new process.In the one pot synthesis of cyclohexylbenzene,the preparation process of the bifunctional catalyst for hydroalkylation is mainly introduced.Finally,the basis and main research contents of this paper are described.Chapter 2:The traditional synthesis process of 3-amino-n-ethyl carbazole was improved.N-ethylcarbazole,an intermediate product,was prepared by liquid-phase catalytic hydrogenation and reduction with acetylene as alkylating agent.In the subsequent reduction of 3-nitro-n-ethyl carbazole,Pd/C and Pt/C noble metal catalysts were used for hydrogenation.When the conversion rate reached 99%,the selectivity of the target product 3-amino-n-ethyl carbazole was about 92%,which reached the goal of industrial production.Chapter 3:A new process for the synthesis of carbazole was developed.Using cyclohexanone and phenylhydrazine as raw materials,1,2,3,4-tetrahydrocarbazole was prepared by Fischer indole reaction,and then dehydrogenation was carried out in two steps with active carbon and Pd/C catalyst.The conversion of 1,2,3,4tetrahydrocarbazole is 92.2%,and the selectivity of carbazole is 98.9%.Chapter 4:A series of bifunctional catalysts were prepared for the selective hydrogenation of benzene to cyclohexylbenzene in one pot.When 0.5%Pd/HY prepared by impregnation is used in the hydrogenation alkylation system,the selectivity of cyclohexylbenzene can reach 48.5%when the conversion of benzene reaches 92.3%.Chapter 5:summarize the research results of this paper,and make a prospect for the actual scale-up production of these processes.