To get high purity caprolactam is a challenging task in the chemical fiber industry. To date, reports on the prediction of the distribution of caprolactam and its derivative chemicals have been few. In this study, the...To get high purity caprolactam is a challenging task in the chemical fiber industry. To date, reports on the prediction of the distribution of caprolactam and its derivative chemicals have been few. In this study, the extraction of caprolactam with toluene as the extractant and N-methyl caprolactam with benzene and toluene as theextractants has been camed out. By defining new UNIFAC groups and calibrating related interaction parameters, aUNIFAC method was introduced to predict the equilibrium concentration of caprolactam and methyl caprolactam intoluene or benzene extraction processes. The calculated results fit very well With the experimental data. Using theUNIFAC model, the selectivity of extractants can be predicted.展开更多
After two decades＇ endeavor, the Research Institute of Petroleum Processing （RIPP） has successfully de- veloped a green caprolactam （CPL） production technology. This technology is based on the integration of tita...After two decades＇ endeavor, the Research Institute of Petroleum Processing （RIPP） has successfully de- veloped a green caprolactam （CPL） production technology. This technology is based on the integration of titanium silicate （TS）-I zeolite with the slurry-bed reactor for the ammoximation of cyclohexanone, the integration of silicalite-1 zeolite with the moving-bed reactor for the gas-phase rearrangement of cyclohex- anone oxime, and the integration of an amorphous nickel （Ni） catalyst with the magnetically stabilized bed reactor for the purification of caprolactam. The world＇s first industrial plant based on this green CPL produc- tion technology has been built and possesses a capacity of 200 kt·a-1. Compared with existing technologies, the plant investment is pronouncedly reduced, and the nitrogen （N） atom utilization is drastically improved. The waste emission is reduced significantly; for example, no ammonium sulfate byproduct is produced. As a result, the price difference between CPL and benzene drops. In 2015, the capacity of the green CPL produc- tion technology reached 3 ×10-6 t·a-1, making China the world＇s largest CPL producer, with a global market share exceeding 50%.展开更多
Mixed solvent of 1-octanol and cyclohexane with 60% （by mass） 1-octanol content was selected as a new extractant for caprolactam extraction. Compared with benzene or toluene, the new extractant has larger extraction...Mixed solvent of 1-octanol and cyclohexane with 60% （by mass） 1-octanol content was selected as a new extractant for caprolactam extraction. Compared with benzene or toluene, the new extractant has larger extraction capacity and much lower toxicity. Although the extraction capacity of the new extractant is smaller than that of pure 1-octanol, 1-octanol solubility of the new extractant in aqueous phase is much smaller. Because of its physical properties of lower density, lower viscosity, and higher interfacial tension, the new extractant performed much better phase separation ability than pure 1-octanol. The new extractant showed certain selectivity when dealing with lactam oil. The mixed solvent of 1-octanol and cyclohexane with 60% （by mass） 1-octanol content is a promising extractant for caprolactam extraction.展开更多
An extended liquid-liquid equilibrium(LLE) UNIFAC model is proposed to describe phase equilibria of mixtures containing caprolactam.In this model,caprolactam is introduced as a new group.New group interaction paramete...An extended liquid-liquid equilibrium(LLE) UNIFAC model is proposed to describe phase equilibria of mixtures containing caprolactam.In this model,caprolactam is introduced as a new group.New group interaction parameters are calibrated from 156 sets of liquid-liquid equilibrium data.The present model gives satisfactory correlation and prediction in liquid-liquid equilibrium,including quaternary systems containing the mixed solvent of an alcohol and an alkane.The model can be applied to predict caprolactam solubility in water and benzene accurately.Freezing point and vapor-liquid equilibrium of binary systems containing caprolactam are also predicted with the extended LLE UNIFAC model.Satisfactory prediction results are obtained.展开更多
The nitrozation reaction of cyclohexane in one-step reaction to form ε-caprolactam has been studied using transition metal salt as catalysts in this work. The results indicated that the catalysts play an especially i...The nitrozation reaction of cyclohexane in one-step reaction to form ε-caprolactam has been studied using transition metal salt as catalysts in this work. The results indicated that the catalysts play an especially important role. This method is expected to be a novel way to synthesize other lactam by similar reaction. The possible mechanism was suggested.展开更多
Caprolactam, which is mainly produced via the Beckmann rearrangement reaction, is an important chemical material. The strict specifications of caprolactam products make the refining process of caprolactam extremely im...Caprolactam, which is mainly produced via the Beckmann rearrangement reaction, is an important chemical material. The strict specifications of caprolactam products make the refining process of caprolactam extremely important. According to the different rearrangement process, the refining process of caprolactam is also different. The main refining sequence of liquid phase rearrangement products includes extraction, ion exchange, hydrogenation, and distillation. The refining process of gas phase rearrangement products is conducted mainly through distillation, crystallization, and hydrogenation. In this paper, the research progress of caprolactam refining technology will be summarized according to different rearrangement reaction processes, which will provide a reference for the selection of appropriate caprolactam refining process.展开更多
Liquid-liquid equilibrium (LLE) data of water-caprolactam-benzene-(NH4)2SO4 system at 303 K were measured for extraction of caprolactam from aqueous ammonium sulfate solution. The influence of fluid flow rate, pulsati...Liquid-liquid equilibrium (LLE) data of water-caprolactam-benzene-(NH4)2SO4 system at 303 K were measured for extraction of caprolactam from aqueous ammonium sulfate solution. The influence of fluid flow rate, pulsation intensity on flooding velocity and mass transfer was studied for extraction of caprolactam from ammonium sulfate solution in a laboratory pulsed packed column. The flooding velocities and overall apparent height of a transfer unit were given under various operation conditions. An industrial column developed based on above study is operated well. The scale-up effect is discussed.展开更多
ε-Caprolactam（CL or CPL） is one of the most important intermediates used in polymer industry for the production of several million tons of nylon-6 every year^[1]. All current commercial processes for the production...ε-Caprolactam（CL or CPL） is one of the most important intermediates used in polymer industry for the production of several million tons of nylon-6 every year^[1]. All current commercial processes for the production of caprolactam are based on either benzene or tolueneI21. Caprolactam is synthesized by the Beckmann rearrangement of cyclohexanone oxime with fuming sulfuric acid or sulfuric acid as the reaction medium, and cyclohexanone oxime is produced by the reaction between cyclohexanone and hydro- xylamine（only one exception is the Toray PNC process）.展开更多
Caprolactam is treated with dimethyl sulfate in benzene medium under conditions of various molar ratios to yield two different methylatcd products. The homogeneous reaction of caprolactam with dimethyl sulfate without...Caprolactam is treated with dimethyl sulfate in benzene medium under conditions of various molar ratios to yield two different methylatcd products. The homogeneous reaction of caprolactam with dimethyl sulfate without any medium can only givc one methylated derivative. In a similar condition to that mentioned above, the reaction of caprolactam with diethylsulfate forms also one product, O-ethyl caprolactim. In this articlc NMR spectrum is applied to further identify the molecular structures of two methylated derivatives held by predecessors, and, applied the chemical shift reagent to induce the NMR and combined the field scanning and decoupling method to confirm the classification of signals, as a consequence the preferred conformation of caprolactam and its alkyl derivatives are proposed.展开更多
Na2WO4‐acidic ionic liquid was used as a simple, ecofriendly, recyclable and efficient catalytic system for the one‐pot conversion of cyclohexanol to ε‐caprolactam. The effect of the structure of the ionic liquid ...Na2WO4‐acidic ionic liquid was used as a simple, ecofriendly, recyclable and efficient catalytic system for the one‐pot conversion of cyclohexanol to ε‐caprolactam. The effect of the structure of the ionic liquid on the catalytic activity of this system was investigated, and the results revealed that sulfonic acid‐functionalized ionic liquids with HSO4? as an anion gave the best results. The highly efficient performance of this catalyst system was attributed to the phase‐transfer behavior of the cation of the ionic liquid, the improved coordination of the substrate to bisperoxotungstate duringthe oxidation reaction, and the stabilization of the intermediate formed during the Beckmann rearrangement.展开更多
A series of caprolactam ionic liquids(ILs) containing incorporated halide anions were synthesized.Their physical properties,such as melting points,heats of fusion and heat capacities,were measured by differential scan...A series of caprolactam ionic liquids(ILs) containing incorporated halide anions were synthesized.Their physical properties,such as melting points,heats of fusion and heat capacities,were measured by differential scanning calorimeter(DSC).The results indicate that these ionic liquids exhibit proper melting points,high value of heats of fusion,and satisfying heat capacities which are suitable for thermal energy storage applications.展开更多
Two-dimensional(2D)oxide nanomaterials have great potential for various applications but face challenges due to strong interlayer interactions.In this work,we propose a novel and facile method to exfoliate layered tra...Two-dimensional(2D)oxide nanomaterials have great potential for various applications but face challenges due to strong interlayer interactions.In this work,we propose a novel and facile method to exfoliate layered transition metal oxides into ultrathin nanosheets functionalized with phosphate species by the combination of ball-milling and liquid-exfoliation with phosphoric acid.The resulting HNb Mo O6nanosheets with supported Pd nanoparticles displayed excellent catalytic performance in the one-pot conversion of phenol into caprolactam(CPL),achieving a yield of up to 71.9%.This one-pot route avoids the energy-intensive intermediate separation process in conventional multi-step approaches to CPL.The superior catalytic performance of the catalysts is attributed to the tunable Bronsted acid/Lewis acid ratio and readily accessible active sites on the ultrathin nanosheets.This research demonstrates a new methodology for constructing ultrathin nanosheets and preparing bifunctional catalysts for tandem reactions,which opens the way for one-pot production of CPL.展开更多
A new synthetic method for the preparation of N-alkylhexahydroazepine by one-step catalytic alkylation and hydrogenation of caprolactam has been developed. Alkylated caprolactam was firstly synthesized by catalytic al...A new synthetic method for the preparation of N-alkylhexahydroazepine by one-step catalytic alkylation and hydrogenation of caprolactam has been developed. Alkylated caprolactam was firstly synthesized by catalytic alkylation of caprolactam with alcohol and then directly hydrogenated into N-alkylhexahydroazepine over Cu-ZnO/γ-Al2O3 catalyst.展开更多
A simple and efficient approach for the synthesis of e-caprolactam via the liquid phase nitrosation of cyclohexane and nitrosyl sulfuric acid in the presence of concentrated sulfuric acid has been developed. A series ...A simple and efficient approach for the synthesis of e-caprolactam via the liquid phase nitrosation of cyclohexane and nitrosyl sulfuric acid in the presence of concentrated sulfuric acid has been developed. A series of novel A1VPO composites were prepared by an impregnation method and the composites were then employed to catalyze the nitrosation reaction of cyclohexane and nitrosyl sulfuric acid. Compared to the reaction using fuming sulfuric acid, the selectivity for the desired product was significantly improved using this one-step catalytic process. This method affords a shortcut to prepare ecaprolactam and its analogs from cyclohexane.展开更多
基金Supported by the National Natural Science Foundation of China （No.20490200, No.20525622）.
文摘To get high purity caprolactam is a challenging task in the chemical fiber industry. To date, reports on the prediction of the distribution of caprolactam and its derivative chemicals have been few. In this study, the extraction of caprolactam with toluene as the extractant and N-methyl caprolactam with benzene and toluene as theextractants has been camed out. By defining new UNIFAC groups and calibrating related interaction parameters, aUNIFAC method was introduced to predict the equilibrium concentration of caprolactam and methyl caprolactam intoluene or benzene extraction processes. The calculated results fit very well With the experimental data. Using theUNIFAC model, the selectivity of extractants can be predicted.
文摘After two decades＇ endeavor, the Research Institute of Petroleum Processing （RIPP） has successfully de- veloped a green caprolactam （CPL） production technology. This technology is based on the integration of titanium silicate （TS）-I zeolite with the slurry-bed reactor for the ammoximation of cyclohexanone, the integration of silicalite-1 zeolite with the moving-bed reactor for the gas-phase rearrangement of cyclohex- anone oxime, and the integration of an amorphous nickel （Ni） catalyst with the magnetically stabilized bed reactor for the purification of caprolactam. The world＇s first industrial plant based on this green CPL produc- tion technology has been built and possesses a capacity of 200 kt·a-1. Compared with existing technologies, the plant investment is pronouncedly reduced, and the nitrogen （N） atom utilization is drastically improved. The waste emission is reduced significantly; for example, no ammonium sulfate byproduct is produced. As a result, the price difference between CPL and benzene drops. In 2015, the capacity of the green CPL produc- tion technology reached 3 ×10-6 t·a-1, making China the world＇s largest CPL producer, with a global market share exceeding 50%.
基金Supported by the National Natural Science Foundation of China （20490200, 20525622） and the National Basic Research Program of China （2007CB714302）.
文摘Mixed solvent of 1-octanol and cyclohexane with 60% （by mass） 1-octanol content was selected as a new extractant for caprolactam extraction. Compared with benzene or toluene, the new extractant has larger extraction capacity and much lower toxicity. Although the extraction capacity of the new extractant is smaller than that of pure 1-octanol, 1-octanol solubility of the new extractant in aqueous phase is much smaller. Because of its physical properties of lower density, lower viscosity, and higher interfacial tension, the new extractant performed much better phase separation ability than pure 1-octanol. The new extractant showed certain selectivity when dealing with lactam oil. The mixed solvent of 1-octanol and cyclohexane with 60% （by mass） 1-octanol content is a promising extractant for caprolactam extraction.
基金Supported by the National Natural Science Foundation of China（20490200 20525622） the National Basic Research Program of China（2007CB714302）
文摘An extended liquid-liquid equilibrium(LLE) UNIFAC model is proposed to describe phase equilibria of mixtures containing caprolactam.In this model,caprolactam is introduced as a new group.New group interaction parameters are calibrated from 156 sets of liquid-liquid equilibrium data.The present model gives satisfactory correlation and prediction in liquid-liquid equilibrium,including quaternary systems containing the mixed solvent of an alcohol and an alkane.The model can be applied to predict caprolactam solubility in water and benzene accurately.Freezing point and vapor-liquid equilibrium of binary systems containing caprolactam are also predicted with the extended LLE UNIFAC model.Satisfactory prediction results are obtained.
基金The authors thank the financial support for this work by the National Natural Science Foundation of China(No.20233040).
文摘The nitrozation reaction of cyclohexane in one-step reaction to form ε-caprolactam has been studied using transition metal salt as catalysts in this work. The results indicated that the catalysts play an especially important role. This method is expected to be a novel way to synthesize other lactam by similar reaction. The possible mechanism was suggested.
文摘Caprolactam, which is mainly produced via the Beckmann rearrangement reaction, is an important chemical material. The strict specifications of caprolactam products make the refining process of caprolactam extremely important. According to the different rearrangement process, the refining process of caprolactam is also different. The main refining sequence of liquid phase rearrangement products includes extraction, ion exchange, hydrogenation, and distillation. The refining process of gas phase rearrangement products is conducted mainly through distillation, crystallization, and hydrogenation. In this paper, the research progress of caprolactam refining technology will be summarized according to different rearrangement reaction processes, which will provide a reference for the selection of appropriate caprolactam refining process.
文摘Liquid-liquid equilibrium (LLE) data of water-caprolactam-benzene-(NH4)2SO4 system at 303 K were measured for extraction of caprolactam from aqueous ammonium sulfate solution. The influence of fluid flow rate, pulsation intensity on flooding velocity and mass transfer was studied for extraction of caprolactam from ammonium sulfate solution in a laboratory pulsed packed column. The flooding velocities and overall apparent height of a transfer unit were given under various operation conditions. An industrial column developed based on above study is operated well. The scale-up effect is discussed.
基金Supported by the National Natural Science Foundation of China(Nos 20233040 and 20572021)
文摘ε-Caprolactam（CL or CPL） is one of the most important intermediates used in polymer industry for the production of several million tons of nylon-6 every year^[1]. All current commercial processes for the production of caprolactam are based on either benzene or tolueneI21. Caprolactam is synthesized by the Beckmann rearrangement of cyclohexanone oxime with fuming sulfuric acid or sulfuric acid as the reaction medium, and cyclohexanone oxime is produced by the reaction between cyclohexanone and hydro- xylamine（only one exception is the Toray PNC process）.
文摘Caprolactam is treated with dimethyl sulfate in benzene medium under conditions of various molar ratios to yield two different methylatcd products. The homogeneous reaction of caprolactam with dimethyl sulfate without any medium can only givc one methylated derivative. In a similar condition to that mentioned above, the reaction of caprolactam with diethylsulfate forms also one product, O-ethyl caprolactim. In this articlc NMR spectrum is applied to further identify the molecular structures of two methylated derivatives held by predecessors, and, applied the chemical shift reagent to induce the NMR and combined the field scanning and decoupling method to confirm the classification of signals, as a consequence the preferred conformation of caprolactam and its alkyl derivatives are proposed.
基金supported by the National Natural Science Foundation of China (20636030, 2090618, 21236001)the Natural Science Foundation of Hebei Province (B2017202226)~~
文摘Na2WO4‐acidic ionic liquid was used as a simple, ecofriendly, recyclable and efficient catalytic system for the one‐pot conversion of cyclohexanol to ε‐caprolactam. The effect of the structure of the ionic liquid on the catalytic activity of this system was investigated, and the results revealed that sulfonic acid‐functionalized ionic liquids with HSO4? as an anion gave the best results. The highly efficient performance of this catalyst system was attributed to the phase‐transfer behavior of the cation of the ionic liquid, the improved coordination of the substrate to bisperoxotungstate duringthe oxidation reaction, and the stabilization of the intermediate formed during the Beckmann rearrangement.
基金Supported by the National Natural Science Foundation of China （21176010, 20706005）.
文摘A series of caprolactam ionic liquids(ILs) containing incorporated halide anions were synthesized.Their physical properties,such as melting points,heats of fusion and heat capacities,were measured by differential scanning calorimeter(DSC).The results indicate that these ionic liquids exhibit proper melting points,high value of heats of fusion,and satisfying heat capacities which are suitable for thermal energy storage applications.
基金supported by the National Key Research and Development Program of China(2022YFA1504901,2023YFA1508103)the National Natural Science Foundation of China(22293012,22179132,22293015,22121002)。
文摘Two-dimensional(2D)oxide nanomaterials have great potential for various applications but face challenges due to strong interlayer interactions.In this work,we propose a novel and facile method to exfoliate layered transition metal oxides into ultrathin nanosheets functionalized with phosphate species by the combination of ball-milling and liquid-exfoliation with phosphoric acid.The resulting HNb Mo O6nanosheets with supported Pd nanoparticles displayed excellent catalytic performance in the one-pot conversion of phenol into caprolactam(CPL),achieving a yield of up to 71.9%.This one-pot route avoids the energy-intensive intermediate separation process in conventional multi-step approaches to CPL.The superior catalytic performance of the catalysts is attributed to the tunable Bronsted acid/Lewis acid ratio and readily accessible active sites on the ultrathin nanosheets.This research demonstrates a new methodology for constructing ultrathin nanosheets and preparing bifunctional catalysts for tandem reactions,which opens the way for one-pot production of CPL.
文摘A new synthetic method for the preparation of N-alkylhexahydroazepine by one-step catalytic alkylation and hydrogenation of caprolactam has been developed. Alkylated caprolactam was firstly synthesized by catalytic alkylation of caprolactam with alcohol and then directly hydrogenated into N-alkylhexahydroazepine over Cu-ZnO/γ-Al2O3 catalyst.
文摘A simple and efficient approach for the synthesis of e-caprolactam via the liquid phase nitrosation of cyclohexane and nitrosyl sulfuric acid in the presence of concentrated sulfuric acid has been developed. A series of novel A1VPO composites were prepared by an impregnation method and the composites were then employed to catalyze the nitrosation reaction of cyclohexane and nitrosyl sulfuric acid. Compared to the reaction using fuming sulfuric acid, the selectivity for the desired product was significantly improved using this one-step catalytic process. This method affords a shortcut to prepare ecaprolactam and its analogs from cyclohexane.
