Preparation Of New VPO Composite Catalysts And Its Catalytic Performance For The Liquid Nitrosation Reaction Of Cyclohexane

ε-Caprolactam(CPL) is an important petroleum chemical industrially rawmaterial and widely used in industrial production. Mainly used for manufacturingchemical fiber and engineering plastics. At present, caprolactam production methods hadmany disadvantages, example: the method required many step reaction and complexoperation; the atomic economic efficiency is not high; and the production of largeamounts of ammonium sulfate as a byproduct. Therefore, to look for a newtechnology that have few steps, simple operation and environmental economic hasbecome the focus. In this test we have a further research with one-step synthesis ofcaprolactam. The influence of the catalysts to the reaction were investigation. And thereaction mechanism were simply explored. Through the data and figure explainedsome phenomenon appear in the experiments.This experimental design and preparation of a few different V/P’s VPO catalysts,and evaluate the impact on the reaction, it is concluded that when V/P is1:12VPOcatalysts have best effect. In this V/P, add transition metal reductive M-VPO andM-AlVPO composite catalysts are prepared with coprecipitation method. And theM/VPO and M/AlVPO composite catalysts are prepared with impregnation method.And the performance of the catalysts to the reaction were inspected in fuming sulfuricacid system. The experiment results is: in the M-VPO series catalysts, Ni-VPOcatalyst show better effect, cyclohexane conversion rate is19.12%, and28.95%forcaprolactam selective; in the M/VPO series catalysts, Cr/VPO catalyst show bettereffect, cyclohexane conversion rate is19.44%, and28.30%for caprolactam selective;in the M-AlVPO series catalysts, Cr-AlVPO catalyst show better effect, cyclohexaneconversion rate is18.68%, and27.58%for caprolactam selective; in the M/AlVPOseries catalysts, Mn/AlVPO catalyst show better effect, cyclohexane conversion rateis16.42%, and29.39%for caprolactam selective.In this experiment, we use concentrated sulfuric acid replace fuming sulfuric acidin order to reduce the amount of benzene sulfonic acid. This is a great improvement ofthis topic. Based on single factor investigation, it is concluded that the more suitableto the reaction conditions: the proportion of NOHSO4and concentrated sulfuric acidis1:3, the response time is24h, reaction temperature is82℃. The reactionmechanism was into the preliminary investigation, We speculate the reaction exists aintermediates. The influence of this series of VPO composite catalysts to the reaction in theconcentrated sulfuric acid system were investigated. We found that it has the similarrules to the fuming sulfuric acid system: in the M-VPO series catalysts, Ni-VPOcatalyst show better effect, cyclohexane conversion rate is4.37%, and77.22%forcaprolactam selective; in the M/VPO series catalysts, Cr/VPO catalyst show bettereffect, cyclohexane conversion rate is4.49%, and75.22%for caprolactam selective;in the M-AlVPO series catalysts, Cr-AlVPO catalyst show better effect, cyclohexaneconversion rate is4.53%, and75.65%for caprolactam selective; in the M/AlVPOseries catalysts, Cu/AlVPO catalyst show better effect, cyclohexane conversion rate is5.54%, and74.74%for caprolactam selective.In the work we have a further study to the one-step synthesis of ε-caprolactam.This for future research work has certain directive significance.