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
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
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 ex-traction of caprolactam with toluene as the extractant and N-methyl caprolactam with benzene and toluene as the extractants has been carried out. By defining new UNIFAC groups and calibrating related interaction parameters, a UNIFAC method was introduced to predict the equilibrium concentration of caprolactam and methyl caprolactam in toluene or benzene extraction processes. The calculated results fit very well with the experimental data. Using the UNIFAC model, the selectivity of extractants can be predicted.展开更多
Recovery of caprolactam from waste water of caprolactam production factory was investigated using benzence as solvent in a small-scale pulsed-sieve-plate column.First,liquid-liquid equilibrium (LLE) deta were measured...Recovery of caprolactam from waste water of caprolactam production factory was investigated using benzence as solvent in a small-scale pulsed-sieve-plate column.First,liquid-liquid equilibrium (LLE) deta were measured,including water-caprolactam-benzene system at low caprolactam concentrations,and waste water-benzene system.Then,the operating regions and mass transfer of the pulsed-sieve-plate column were measured.Finally,the overall apparent heights of a transfer unit based on continuous phase are correlated in terms of the column operation variables.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
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
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
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.
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 (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 ex-traction of caprolactam with toluene as the extractant and N-methyl caprolactam with benzene and toluene as the extractants has been carried out. By defining new UNIFAC groups and calibrating related interaction parameters, a UNIFAC method was introduced to predict the equilibrium concentration of caprolactam and methyl caprolactam in toluene or benzene extraction processes. The calculated results fit very well with the experimental data. Using the UNIFAC model, the selectivity of extractants can be predicted.
基金Partly supported by UK's Academic Link with China Scheme (ALCS: SHA/992/307), British Council.
文摘Recovery of caprolactam from waste water of caprolactam production factory was investigated using benzence as solvent in a small-scale pulsed-sieve-plate column.First,liquid-liquid equilibrium (LLE) deta were measured,including water-caprolactam-benzene system at low caprolactam concentrations,and waste water-benzene system.Then,the operating regions and mass transfer of the pulsed-sieve-plate column were measured.Finally,the overall apparent heights of a transfer unit based on continuous phase are correlated in terms of the column operation variables.
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.
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 (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.