Liquid-phase Beckmann Rearrangement Of Cyclohexanone Oxime And Preparation Of Nitrocyclohexane

?-Caprolactam is an important precursor of nylon-6 and plastics. Up to date, many methods have been developed for the manufacture of caprolactam. Most of caprolactam is produced from cyclohexanone, which is first converted to its oxime, and then treated the oxime with oleum as both solvent and cataly to obtain caprolactam. However, this process has several disadvantages, such as formation of large amount of ammonium suifuric as a by-product due to the neutralization of the hazardous sulfuric acid with ammonia, and corrosion of thereactors and environmental pollution caused by the use of fuming sulfuric acid. During the production process, no matter which method is used, the impurity, especially during the cyclohexanone oxime rearrangement step, is brought to the product of caprolactam through the intermediate by-products. This process is ecologically and economically questionable, due to it is energy intensive and generates considerable wastes. We explored a new mild acid-formic acid to replace the oleum as both solvent and cataly to rearrange cyclohexanone oxime. In consideneration of the disadvantage of oxime as raw material to obtain caprolactam, imagine the nitrocyclohexanone as raw material, can not only shorten the reaction process,reduce energy consumption, less by-product, and the mild reaction condition to easy control. In the work, We using a green nitrating agent NO₂ nitration of cyclohexane to produce nitrocyclohexane.First of all, explore the influence on the reaction of formic acid and dehydrated formic as solvent and cataly, the effect of acid oxime ratio, reaction temperature and reaction time, reaction conditions on the cyclohexanone oxime rearrangement reaction. It was found that the optimum reation condition of the rearrangement reaction are follows: using formic acid as solvent and cataly, the quality ratio of acid to oxime is 20:2, react under atmosphere pressure and reaction temperature than 100-110? for 1 hour. Under the above condition, the conversion rate of cyclohexanone oxime can be up to 100%, and the selectivity of caprolactam was 29.59%.Secondly, the thesis investigated the reactant molar ratio of cyclohexane to NO₂ and reaction tempreture during the process of catalytic reaction of cyclohexane and NO₂ in autoclave devices. What's more, the effect of injection of NHPI and O2 was also studied. It confirmed that under the condition of molar ratio of cyclohexane to NO₂ remains at 15:1, reaction tempreture controled at 70?, and residence time set at 4h,selectivity of nitricyclohexane reached as high as 48.34%. Oxygen feeding increased the oxidability of NO₂, and more oxidation products were produced. When NHPI was added, no adipic acid was produced, conversion ratio of NO₂ was increased a little, nitrocyclohexane selectivity showed no obvious increase.Finally, the catalytic reaction of nitrocyclohexane with NO₂ at atmospheric pressure was investigated. Appropriate catalyst were selected from the metal salt catalysts available in the lab, NHPI acted out the best nitrification effect.Therefore, NHPI was choosen as the catalyst for the investigation of single factors like residence time and reaction tempreture. Under the condition of molar ratio of cyclohexane to NO₂ remains at 15:1, reaction tempreture controled at 70?, after 4h residence time, NO₂ conversion rate reached up to 77.29%, selectivity of cyclohexane reached up to 70.25%. Recycling utilization of recycled NHPI catalyst showed that there is no change of catalytic activity of NHPI after three times circulation.