Study On The Liquid-phase Nitration Of Cyclohexane To Nitrocyclohexane By Solid Super Acid

At present, the nitation of hydrocarbon is mainly concerned with aromatic hydrocarbon, and its nitration technology has been widely applied in industrial production, while the research of the nitration of aliphatic hydrocarbon is rare, mainly for low carbon alkane and cycloparafin hydrocarbon, which usually adopt traditional vapor phase nitration method. Although it can obtain higher conversion, it cause to produce many by-products with high energy consumpion and it is difficult to get nitro products with high purity under higher temperature. Therefore, it is meaningful to search for an low temperature catalytic nitration route to produce nitro products from low carbon alkane and cycloparafin hydrocarbon.In the fist part of this thesis, qualitative analysis of the cyclohexane nitration products was carried out. A rapid and accurate quantitative analysis method was established to analyse cyclohexane and the main product by using chlorinated benzene as internal standard content.In the second part, three different P-Mo-V heteropoly acids were synthesized by multi-step method and characterized by IR. The results indicate that they all have Keggin structure. Then, the catalytic performance of these three different heteropoly acids on cyclohexane nitration was investigated. The results show that these three different heteropoly acids have certain catalytic activity. The process of cyclohexane nitration used H₄PMo₁₁VO₄ as catalyst was optimized, the results show that the yield of nitrocyclohexane is 7.74%, under the optimal condition.Then, SO₄^2-/ZrO₂ was prepared by precipitation method and characterized by IR. The IR spectrum indicates that the catalyst has characteristic absorption peaks of solid super acid. In order to optimize the reaction conditions, the reaction temperature, the reaction time, pressure, amount of the catalyst and concentration of nitric acid were investigated respectively. The optimal conditions of the reaction were as follows: 105℃of reaction temperature; 36h of reaction time; 1.5MPa of reaction pressure; SO₄^2-/ZrO₂:cyclohexane=1:40 (w/w) and 26.00% of the concentration of nitric acid. The yield of nitrocyclohexane was 19.23% under the optimal condition.The factors which affected the solid super acid catalyst on catalytic activity were studied, including ageing temperature, roasting temperature, roasting time and concentration of sulphuric acid. The result shows that the solid super acid made by using ammonia as precipitation agent, ageing in room temperature, impregnating in 1.0 mol/L H₂SO₄, calcinating at 550℃and 3h of roasting time gives better result. Then, the catalysts prepared in different conditions were characterized by IR, XRD, TG, BET and Particle size analyzer to find the relationship between catalyst structure and catalytic activities.