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Study On The Process Of Hydrogenation Of Nitrocyclohexane By Pd Supported Nanotubes

Posted on:2013-03-15Degree:MasterType:Thesis
Country:ChinaCandidate:H K ZhangFull Text:PDF
GTID:2251330401450748Subject:Chemical Engineering
Abstract/Summary:PDF Full Text Request
Cyclohexanone oxime is an important intermediate used to produce caprolactam, which is an important raw material in the synthesis of nylon-6fibers and resins. There exist some considerable disadvantages of the traditional production routes of cyclohexanone oxime, such as, complex and long technique processes, high equipment investment, a great deal of ammonium sulfate by-product. Therefore, researchers have tried to develop a green, economical, environment friendly cyclohexanone oxime production route. Partial catalytic hydrogenation of nitrocyclohexane to cyclohexanone oxime has an obvious advantage, such as simple technological process, mild reaction conditions, no ammonium sulfate by-product, simple operation. The effects of different catalyst systems on partial hydrogenation of nitrocyclohexane to Oxime and the mechanism of the process.In this study, the products of partial hydrogenation of nitrocyclohexane were identified by GC-MS. Gas chromatography was used to establish a quantitative analysis method for nitrocyclohexane, cyclohexanone oxime, cyclohexylamine and cyclohexanol. Furthermore, the product of cyclohexane nitration was purified and the content of nitrocyclohexane is above95%.Firstly, we’ve investigated the influences of different active components, supports and solvents on partial hydrogenation of nitrocyclohexane. It was found that the Pd supported on activated carbon or carbon nanotubes(CNT) catalysts have obvious better catalytic performance in this process, using ethylenediamine as solvent.We focused on the process of partial hydrogenation of nitrocyclohexane using Pd supported on activated carbon or carbon nanotubes as catalysts.5%Pd/C and5%Pd/CNTs were characterized by N2adsorption-desorption, XRD, TEM, XPS and H2chemisorption, and the state of Pd+is beneficial to this reaction. The results showed that5%Pd/SWCNT gave the best catalytic performances, the conversion of nitrocyclohexane was97.3%and the selectivity to cyclohexanone oxime was up to94.6%. After recycling, the performance of the catalyst had a bit decrease.The partial hydrogenation of nitrocyclohexane using5%Pd/SWCNT as catalyst was optimized. The best reaction conditions were obtained, reaction time was6h, temperature is50℃, hydrogen pressure is0.5MPa, the conversion of nitrocyclohexane was97.7%and the selectivity to cyclohexanone oxime was up to97.4%. Moreover, we preliminarily explored the mechanism of the process, it was found that the intermediate products include cyclohexyl-hydroxylamine and N,N-2hydroxy cyclohexane, and when compared with the main reaction, the reaction to cyclohexylamine is a parallel reaction, whereas the reaction to cyclohexanol is a consecutive reaction.
Keywords/Search Tags:nitrocyclohexane, partial hydrogenation, cyclohexanone oxime, 5%Pd/CNT
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