Studies On The Nitration Of Cyclohexane And Catalytic Hydrogenation Of Nitrocyclohexane

Cyclohexanone oxime is an important fine chemical intermediateand widely used in producing caprolactam which is currently produced bythe reaction of cyclohexane with hydroxyl amine followed by aBeckmann rearrangement with sulfuric acid, the efficiency for theproduction of cyclohexane by aerobic oxidation of cyclohexane is nothigh, what's more, the hydroxyl amine need to be reduced by othermethods. So it has realizable and theoretical meaning to searching for aindustrial route to produce cyclohexanone oxime. In this thesis, thevapor-phase nitration of cyclohexane under atmosphere and catalytichydrogenation nitrocyclohexane to synthesize cyclohexanone oxime havebeen investigated, which affords some basic studies for improving therelated production technology.Firstly, the analytic method of nitrocyclohexane and cyclohexanoneoxime was established. According to the method products of nitration ofcyclohexane and selectively hydrogenation of nitrocyclohexane wereidentified by GC-MS. The quantitative analysis of nitrocyclohexane andcyclohexone oxime in the products of nitration of cyclohexane andhydrogenation of nitrocyclohexane were performed by using FID,5%-phenyl-95%-dimethylpolysiloxane capillary column aschromatographic column and o-chlorotoluene as internal standard. Thecalibration factors of nitrocyclohexane and cyclohexone oxime were 1.35 and 1.62, respectively. The changes of enthalpy and entropy of thechromatographic process were estimated.Secondly, the nitration of cyclohexane in the absence of anycatalysts was studied, the effects of reaction temperature, molar ratio ofcyclohexane to NO₂ and residence time on the nitration of cyclohexanewere investigated. At the reaction temperature Of 240℃, the selectivity ofnitrocyclohexane was up to 89.31%. On the base of the results, thepossibility of nitration of cyclohexane with NO₂ in the presence of zeolitecatalysts was explored. Among various solid acid catalysts the zeoliteβshowed good activity, when reaction temperature is 320℃, molar ratio ofcyclohexane to NO₂ is 1.0, WHSV is 7.75h^-1, the conversion ofcyclohexane was up to 15.66% and selectivity of nitrocyclohexane wasup to 82.0%.At last, the nitrocyclohexane was used as start material, CuCl₂,CuBr₂, and soon were used as catalyst, the effect of catalyst on thehydrogenation of nitrocyclohexane was investigated. It is found thatCuCl₂ showed good catalytic activity; the reaction mechanism ofhydrogenation was discussed when used CuCl₂ as catalyst andethylenediamine as solvent. Based on the results, the reaction ofhydrogenation by using Pd/C as catalyst was investigated, when reactiontemperature is 95℃, the conversion of nitrocyclohexane was up to 100%and selectivity of cyclohexanone oxime was up to 84.20%. The effect of content of base in solvent was investigated, it was found that theselectivity of cyclohexanone oxime increased with the content of baseincreased.