Impurity Formation in the Beckmann Rearrangement of Cyclohexanone Oxime to Yield ε-Caprolactam

Zhang, Jisong; Li, Liantang; Wang, Kai; Du, Chencan

doi:10.1021/acs.iecr.7b03824

Cited by 9 publications

(8 citation statements)

References 30 publications

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“…The main reaction and by‐product reactions in the oleum system were described in our previous work, which is shown in Scheme . The hydrolysis of CHO to form CYC was considered as the main side reaction.…”

Section: Resultsmentioning

confidence: 99%

“…The final extracted organic solution was analyzed by GC (Shimadzu, GC‐2014) using the same column and method in our previous work . The external method was used to quantify the concentrations of by‐products, CHO and CPL within a measurement error of <1% and the content of each component ( M ) and selectivity to CPL ( S ) were calculated using the following equations:

M_{i} (() %) = \frac{f_{i} A_{i}}{\sum f_{j} A_{j}} \times 100

S (() %) = \frac{f_{CPL} A_{CPL} - f_{CPL} A_{CPL 0}}{\sum_{i} f_{i} A_{i} - f_{CPL} A_{CPL 0}} \times 100

where, M is the mass fraction, f is the correction coefficient of the GC external standard method, A is the peak area and subscript i and j represent different components detected by GC.…”

Section: Methodsmentioning

confidence: 99%

“…The final extracted organic solution was analyzed by GC (Shimadzu, GC-2014) using the same column and method in our previous work. 21 The external method was used to quantify the concentrations of byproducts, CHO and CPL within a measurement error of <1% and the content of each component (M) and selectivity to CPL (S) were calculated using the following equations:…”

Section: Measurement Of Selectivitymentioning

confidence: 99%

“…The main reaction and by-product reactions in the oleum system were described in our previous work, 21 catalytic system. In all conditions, the contents of by-products were too low to be detected by HPLC.…”

Section: Concentration Profilementioning

confidence: 99%

“…In our previous study, 21 we have studied the reaction catalyzed by oleum and built the relationship between impurity formation and experimental parameters. By-products were mainly formed owing to the condensation and dehydrogenation, which were caused by local nonuniform concentration and temperature.…”

Section: Introductionmentioning

confidence: 99%

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A modified mixed‐acid catalytic system for Beckmann rearrangement of cyclohexanone oxime

Zhang

et al. 2019

AIChE Journal

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ε-Caprolactam (CPL) is mainly produced through Beckmann rearrangement of cyclohexanone oxime catalyzed by oleum in industry nowadays, which suffers the problems like high viscosity and bad mixing, leading to multiple by-products. To this end, a modified mixed-acid catalytic system containing oleum and trifluoroacetic acid (TFA) was proposed to intensify the reaction. The viscosity of the reaction system was studied and the effects of several experimental parameters on the reaction rate and selectivity were also investigated, including oleum/oxime ratio, TFA/oleum ratio, temperature, and SO 3 concentration. Extremely high selectivity (>99.6%) was obtained under all conditions, revealing that by-products in industrial process were mainly formed owing to the insufficient mixing and poor mass and heat transfer rather than experimental parameters. A preliminary mathematical model considering the effect of CPL was developed to predict the reaction rate. These results are helpful to improve the industrial process of CPL production.

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Section: Resultsmentioning

confidence: 99%

M_{i} (() %) = \frac{f_{i} A_{i}}{\sum f_{j} A_{j}} \times 100

S (() %) = \frac{f_{CPL} A_{CPL} - f_{CPL} A_{CPL 0}}{\sum_{i} f_{i} A_{i} - f_{CPL} A_{CPL 0}} \times 100

where, M is the mass fraction, f is the correction coefficient of the GC external standard method, A is the peak area and subscript i and j represent different components detected by GC.…”