Study On The Solid Acid、HY Molecular Sieve Catalyst And The Supported Catalysts Preparation And Catalytic Cyclohexane Nitrosation Reaction

Caprolactam, a kind of important petroleum chemical product and chemical fibermaterial, is a main raw material in manufacturing polyamide fiber and resin.Nowadays, the most significant manufacturing technologies in industry production ofCPL include cyclohexanone-hydroxylamine method, PNC method and SNIA method.All current classical processes for ε-caprolactam are based on benzene, phenol ortoluene. Most of the ε-caprolactam production is still based on the classicaltechnologies, which cyclohexanone oxime is synthesized from cyclohexanone andhydroxylamine sulfate, following with Beckmann rearrangement to obtainε-caprolactam production in the presence of oleum.However,it has disadvantages ofmultiple steps, complicated reactions, low atomic economy, corrosion of the facilitiesand serious environmental problems. Consequently, a new kind of green technology ison a urgent way to apply to simplify the present route and reduce energy consumptionand production cost. Based on our team’s precious work on the novel one stepnitrosation of cyclohexane to caprolactam, this paper is to study on preparation andapplication of several kinds of catalysts, investigate the properties of the catalysts innitrosation one-step of cyclohexanone to caprolactam, and then optimize the reactionconditions.The influence of catalyst preparation factors on the structure propertiesand catalytic performance is carried out.SO42-/ZrO2solid acid catalyst was prepared by Precipitation and co-precipitationmethods and used in the reaction of cyclohexanone nitrosation. The results indicatethat it is hard to obtain ε-caprolactam when the oleum is replaced by solid acid incyclohexane nitrosation.Under the reaction medium of lieum,the conversion ofcyclohexane and the selectivity of caprolactam are both less than30%over these solidacid catalysts.Ion exchange method is used to prepare HY molecular sieves and the relevantsupported catalysts are prepared by wet impregnation method and used in the reactionof cyclohexanone nitrosation. The optimum conditions is obtained over the HYcatalyst in the presence of concentrated sulfuric acid, catalysts0.5g,98wt%concentrated sulfuric acid24g, nitrososulfuric acid8g, reaction time48h. It gave theresult of cyclohexane conversion of6.75%and the73.53%selectivity to caprolactam.Wet-impregnation method is used to prepare PW-HY catalyst and the optimum preparation conditions of the catalysts are obtained30%PW-HY catalyst calinated at450℃for4h has suitable BET surfance area and gives better catalytic performanceof74.2%selectivity to caprolactam to with cyclohexane conversion of12.83%.Compared with HY molecular sieves catalysts, the catalyst supported withphosphotungstic possesses Br nsted acid center, which may be is the selective site inthe reaction of cyclohexane nitrosation.In conclusion,Several kinds of catalysts are prepared,and used in one-stepsynthesis of ε-caprolactam from cyclohexanone nitrosation.The influence ofdifference reaction medium on the reaction of cyclohexane nitrosation to caprolactamwas investigated.