Research Progress in Refining Process for Production of Caprolactam by Beckman Rearrangement Reaction

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.

One-step Synthesis of ε-Caprolactam by the Liquid Phase Nitrosation of Cyclohexane over the Catalysts Containing CH_3COO^- or —COOH

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）.

RESEARCH ON CONFORMATION OF CAPROLACTAM AND ITS ALKYL DERIVATIVES

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.

Distribution Coefficient of Caprolactam and Methyl Caprolactam Using Benzene or Toluene as Extractants： Experiments and Prediction

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.

Selection and Evaluation of a New Extractant for Caprolactam Extraction

有 60% 的 1-octanol 和环己烷的混合溶剂(由质量) 1-octanol 内容为己内酰胺抽取作为新提炼之物被选择。与苯或甲苯相比，新提炼之物有更大的抽取能力和低得多的毒性。尽管新提炼之物的抽取能力比纯 1-octanol 的小，在水的阶段的新提炼之物的 1-octanol 溶解度小得多。因为它更低的密度，更低的粘性，和更高界面的紧张的物理性质，新提炼之物比纯 1-octanol 执行了好一些的阶段分离能力。新提炼之物看了某些选择是否处理酮油。有 60% 的 1-octanol 和环己烷的混合溶剂(由质量) 1-octanol 内容是为己内酰胺抽取的有希望的提炼之物。

Recovery of Caprolactam from Waste Water in Caprolactam Production Using Pulsed-sieve-plate Extraction Column

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.

Phase Equilibrium Calculations in Mixtures Containing Caprolactam with a UNIFAC Model

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.

Extraction of Caprolactam from Aqueous Ammonium Sulfate Solution in Pulsed Packed Column Using 250Y Mellapak Packings

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.

Thermodynamic Properties of Caprolactam Ionic Liquids

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.

Crystal Sructure of Trinitratotri （Butylcaprolactam）Terbium（Ⅲ）Tb[CH2

ＣｒｙｓｔａｌＳｔｒｕｃｔｕｒｅｏｆＴｒｉｎｉｔｒａｔｏｔｒｉ（Ｂｕｔｙｌｃａｐｒｏｌａｃｔａｍ）Ｔｅｒｂｉｕｍ（Ⅲ）Ｔｂ［ＣＨ_２（ＣＨ_２）_４ＣＯＮＣ_４Ｈ_９］_３（ＮＯ_３）_３ＷＡＮＧＨａｎ－Ｚｈａｎｇ；ＸＵＱｉｎｇ－Ｆｅｎｇ；ＱＩＡＮＰｕ；ＣＡ...

手性δ-取代己内酰胺化学/酶串联一锅法合成及立体构型调控

报道了一种以1-取代高烯丙基胺为原料,结合酶催化动态动力学拆分与分子内烯烃复分解反应串联一锅法制备手性δ-取代己内酰胺的方法。分别用脂肪酶和蛋白酶作为动态动力学拆分催化剂,实现了手性δ-取代己内酰胺立体构型的调控。通过该方法制备的R-δ-取代己内酰胺的对映体过量值(enantiomeric excess,ee)均在90%以上,产率维持在76%以上;所制备的S-δ-取代己内酰胺的ee也在82%以上,产率均高于70%。

乙撑胺改性纯硅分子筛用于环己酮肟气相重排制已内酰胺

通过环己酮肟(CHO)气相Beckmann重排工艺制备己内酰胺(CPL)是一条绿色环保的生产工艺,但是气相Beckmann重排催化剂的性能始终制约着该工艺的工业化应用。为了强化气相Beckmann重排催化剂的性能,利用分子尺寸不同的乙撑胺对纯硅分子筛进行了改性。采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)和N_(2)吸/脱附测试等方法对改性纯硅分子筛进行了表征,同时进行了CHO气相Beckmann重排的催化剂的催化性能评价。结果表明,乙撑胺改性的纯硅分子筛保持了原有的MFI型拓扑结构,Brunner-Emmet-Teller(BET)比表面积减小至354.1 m^(2)/g,CPL选择性增大至97.00%。对反应温度、CHO重时空速和质量分数对CHO气相Beckmann气相重排的影响进行了考察,优化得到的最佳反应工艺为:反应温度370℃,CHO重时空速1.0 h^(-1),CHO质量分数30%。在最佳工艺条件下,S-1-B催化剂的CHO转化率≥99.90%,CPL选择性≥97.00%,催化剂单程运行寿命达1200 h且再生性能稳定,具有良好的工业应用前景。

预/共辐照条件下改性塑化淀粉的制备

采用低剂量辐照技术对玉米淀粉进行改性处理,将预辐照、共辐照淀粉分别与己内酰胺、丙三醇按比例混合均匀,使用双螺杆挤出机进行混炼,经低温冷冻粉碎、索氏提取对萃取产物结晶度、分子结构和化学键、热力学性能、化学成分、亲疏水性等进行分析。结果表明:采用同一辐照剂量,不同辐照方式,淀粉与己内酰胺反应后,热稳定性均有所提高;己内酰胺成功接枝到玉米淀粉上,导致淀粉晶面发生改变,试样表面含氮量提高;水接触角增大,其中,共辐照接枝物水接触角达99.229°,疏水性大幅提升,并且拉伸强度达到8.3 MPa。

糠醇-己内酰胺协同改性松木理化性能

糠醇改性木材拥有较多的优点,如优异的耐腐性、耐候性、硬度等,然而经过糠醇改性的木材脆性增加,抗弯性能以及抗剪切性能均有所降低。这一缺点极大限制了糠醇改性木材的应用范围,可通过加入柔性物质己内酰胺以提高糠醇改性木材的韧性。己内酰胺是聚酰胺切片的原材料,韧性较强,常用来制备纤维等柔性材料。将己内酰胺与糠醇复合改性剂协同处理马尾松,通过X射线能谱仪(EDS)、抗弯性能分析、数字图像分析(DIC)以及接触角测试分析研究协同改性对松木早晚材微观构造、元素分布、力学性能和疏水性等的影响。能谱结果表明:由于早晚材结构差异,协同改性剂在早材细胞壁和细胞腔中反应程度更高,聚合物含量更丰富。晚材构造阻碍了改性剂在其内部的渗透,导致晚材反应程度低于早材。木材疏水性结果表明,协同改性大幅提高了木材的疏水性。力学性能以及数字图像分析结果表明,协同改性不仅提高了木材的静曲强度和弹性模量,而且降低了糠醇改性导致的木材脆性。

环己酮肟的合成工艺研究

环己酮肟是生产化工原料己内酰胺的关键中间体。文章总结了近年来环己酮肟的生产工艺及其优缺点,例如环己酮羟胺法、氨肟化法、环己烷光亚硝化法、环己烯法、硝基环己烷法、环己胺法,以期为寻求一条经济、绿色的环己酮肟合成新路线提供一定的参考价值。

臭氧微气泡协同氧化处理己内酰胺生产废水的效能研究

以己内酰胺生产废水中的环己酮肟为目标污染物,优化了微气泡产生方式、臭氧微气泡协同氧化工艺及工艺参数,探究了废水的处理效能和降解机理。从降解效果、臭氧利用率及能耗等角度在加压溶气、机械剪切和微孔曝气盘3种臭氧微气泡产生方式中优选出微孔曝气盘方式,其环己酮肟降解率可由常规大气泡的45.7%升至72.0%。在H_(2)O_(2)、过一硫酸盐(PMS)以及活性γ-Al_(2)O_(3)小球催化剂与臭氧微气泡的协同氧化工艺中,臭氧微气泡协同PMS氧化工艺对环己酮肟的降解效果最好,降解速率常数可达0.1830 min^(-1)。臭氧微气泡协同PMS氧化工艺的最佳PMS投加量为5μmol/L、臭氧投加量为10.0 mg/min、废水pH为9,该条件下反应15 min,环己酮肟降解率可达95%以上。

尼龙-6单体己内酰胺绿色生产技术

中石化石油化工科学研究院有限公司历经30年持续创新,成功开发尼龙-6单体己内酰胺绿色生产技术,主要包括:环己烯酯化加氢制环己酮绿色合成新途径,空心TS-1分子筛与浆态床集成用于环己酮氨肟化,S-1分子筛与移动床集成用于环己酮肟气相贝克曼重排,非晶态镍催化剂与磁稳定床集成用于己内酰胺精制。与引进己内酰胺生产技术相比,碳原子和氮原子利用率明显提升,三废排放显著减少,无副产低价值硫酸铵,装置投资大幅下降,生产成本明显减少。

废旧尼龙6回收技术的研究进展

总结了近年来国内外尼龙6物理和化学回收等方面的研究情况,首先介绍了废旧尼龙6的预处理流程,然后介绍了4种废旧尼龙6的回收技术,包括填埋处理、能量回收、物理回收及化学回收,着重介绍了化学回收中的水解、氨解、醇解和离子液体法及优缺点,并探讨了废旧尼龙6回收技术在工业中的实际应用。目前,化学回收技术所需反应条件较为苛刻,对反应设备的要求较高,未来温和、低能耗、绿色是化学回收技术发展的主要方向。