Study On The Process Of Nitrobenzene Hydrogenation And Direct Catalytic Synthesize Cyclohexanol(Cyclohexanone)

Cyclohexanol and cyclohexanone are very important organic chemical materials an d intermediates in the process of producing caprolactam.Nitrobenzene is a kind of r aw material with low price and widespread source.In the thesis,we proposed a pro cess of synthesizing cyclohexanol and cyclohexanone with nitrobenzene as raw mater ial and study the reaction process systematically,including the choice of catalysts an d optimization of operating conditions.The 2%Pd/MCM-41 catalyst was developed in the process of synthesizing cyclohexanone with nitrobenzene.The reaction process was studied with single factors test,the optimal operating conditions were as follows:0.780g 2%Pd/MCM-41,4mmol nitrobenzene,4mmol AlCl₃,0.56mol water,180?,1.0MPa H₂,1h.Under the conditions,Nitrobenzene conversion was up to 94.30%and the yield of cyclohexanone was 49.80%.while adding 4mmol hydroxylamine to the reaction system,the nitrobenzene conversion was 94.00%and the total yield of cyclohexanone and cyclohexanone oxime can reach63.10%.The experiment results indicate that AlCl₃ can activate the benzene ring of nitrobenzene.Therefore,the hydrogenation reaction of benzene ring can be completed under low temperature and low pressure.At the same time,AlCl₃ can also stabilize the cyclohexanone and prevent its further hydrogenating to cyclohexanol.By studying the effects of reaction time and comparing the reaction results of different reactants,the reaction mechanism of synthesizing cyclohexanone and cyclohexanone oxime with nitrobenzene has also been inferred.The 1%Ru/AC catalyst was developed in the process of synthesizing cyclohexanol with nitrobenzene.The reaction process was studied with single factors test and the optimal operation conditions were as follows:0.410g 1%Ru/AC,16.25mmol nitrobenzene,9.44mol water,0.11mol tertiary butanol,180?,3.0MPa H₂,8h.Under the conditions,the nitrobenzene conversion was 100%and the yield of cyclohexanol was nearly 100%.During the experiment we found that the kinds of metal active centers have a great influence on the yield of cyclohexanol.On the same catalyst support,the yield of cyclohexanol from high to low in the following order of metal active center:Ru>Rh>Pt>Pd.By investing the effects of reaction time and comparing the reaction results of different catalysts,two reaction paths of directly synthesizing cyclohexanol with nitrobenzene have been inferred.The process of hydrogenation and hydration reaction of benzene ring with different replaced group were also investigated,the results show that the benzene ring which contains NH or NH2 can occur hydration reaction and get cyclohexanol,but the yield of cyclohexanol are greatly affected by the adjacent groups.