环己酮肟气相重排制备己内酰胺工艺

报道了一种具有MFI结构的高硅亚微米级分子筛MS1,该分子筛制备工艺简便、成本低、环境友好。研究了MS1分子筛催化环己酮肟气相Beckmann重排制备己内酰胺的催化效果,考察了汽化温度、反应温度、环己酮肟浓度及质量空速（WHSV）等反应条件对环己酮肟气相Beckmann重排反应的影响;在优化的反应条件下环己酮肟转化率≥99.5%,己内酰胺选择性达95%,且催化剂稳定性较好;结果表明,MS1分子筛催化剂具有良好的工业化应用前景。     

Acidity Control and Catalysis of Pentasil Zeolites

Acidities of pentasil zeolites were measured and correlated with aluminum content using the following methods: (1) Acid-base indicator method, (2) NH₃-TPD spectra, (3) GC pulse adsorption of pyridine and 4-methylquinoline, and (4) FTIR spectroscopy of adsorbed pyridine.

By controlling the acidity of pentasil zeolites, we have succeeded in obtaining high catalytic performance both in paraselective dealkylation of cymenes and in vapor-phase Beckmann rearrangement of cyclohexanone oxime to ?-caprolactam. In the dealkylation, moderate acidity of Li-ZSM-5 was the key to avoid side reactions while keeping a high conversion of cymenes. In the Beckmann rearrangement, neutrality and crystallinity of the pentasil zeolite were keys to obtain a high lactam selectivity, and a high lactam selectivity of 95% was attained by the surface treatment with chlorotrimethylsilane. The active sites were elucidated to be neutral silanols on the external surface of zeolite.     

Influences of ethylenediamine treatment of Silicalite-1 on the catalytic vapor-phase Beckmann rearrangement of cyclohexanone oxime

Silicalite-1 was modified by organic base of ethylenediamine. The characterization results indicated that after alkaline treatment, the crystal structure of S-1 was not destructed or changed; the silanol nests were maintained, but the terminal silanol groups were eliminated. The modified S-1 exhibited better performance in the vapor-phase Beckmann rearrangement of cyclohexanone oxime to ε-caprolactam, especially in terms of the stability. It is inferred that the silanol nests are the most suitable centers for the Beckmann rearrangement reaction, while the terminal and vicinal silanol groups might be responsible for the coke deposition.     

Self-catalyzed direct amidation of ketones: A sustainable procedure for acetaminophen synthesis

High yielding amination of ketones and benzaldehyde in acid-less conditions has been conducted on several ketones to achieve amides and nitriles. The reactivity of the selected substrates showed to depend on both oximation and Beckmann rearrangement reaction rates. Oximation allows the in-situ production of hydrochloric acid that enables Beckmann rearrangement of the oxime to form the corresponding amide or nitrile. It is noteworthy that, using this one-pot synthetic approach, N-acetyl-4-aminophenol (acetaminophen drug), can be easily synthesized starting from 4-hydroxy-acetophenone in high yield. Acetanilide and ε-caprolactam can be also efficiently synthesized employing this synthetic procedure.     

Vapor phase reaction of cyclohexanone oxime over boria modified HSZM-5 zeolites

The vapor phase Beckmann rearrangement of cyclohexanone oxime has been carried out over zeolites and boria modified HZSM-5 zeolites to elucidate the effects of acidity and acid strength distribution on the conversion and ε-caprolactam selectivity. Although ε-caprolactam selectivity was increased with the SiO₂Al²O³ ratio in a HZSM-5 zeolite, the highest selectivity in the study was accomplished over a boria modified HZSM-5. The selectivity was dependent on the ratio of weak acid sites to strong acid sites. The boria played an important role in controlling the acid strength distribution of the zeolites. It was found that the production of a polymer over strong acid sites caused a decrease in ε-caprolactam selectivity during the reaction.     

S-1催化环己酮肟气相Beckmann重排反应动力学

目前尼龙6生产中主要采用发烟硫酸催化环己酮肟液相Beckmann重排制己内酰胺,副产大量硫酸铵,而且存在设备腐蚀等问题。采用气相重排法可以克服上述缺点。本工作在以前得到的优化反应条件下,根据实验并采用催化剂失活的Wojciechowski模型获得了S-1催化环己酮肟气相Beckmann重排制己内酰胺反应动力学方程及参数。该模型将催化剂的活性与在线反应时间相关联,进而可以计算任何在线反应时间时催化剂的失活速率,或者根据要求的转化率最低允许值计算催化剂能在线反应的时间。     

Acidity Control and Catalysis of Pentasil Zeolites

Acidities of pentasil zeolites were measured and correlated with aluminum content using the following methods: (1) Acid-base indicator method, (2) NH₃-TPD spectra, (3) GC pulse adsorption of pyridine and 4-methylquinoline, and (4) FTIR spectroscopy of adsorbed pyridine.

By controlling the acidity of pentasil zeolites, we have succeeded in obtaining high catalytic performance both in paraselective dealkylation of cymenes and in vapor-phase Beckmann rearrangement of cyclohexanone oxime to ε-caprolactam. In the dealkylation, moderate acidity of Li-ZSM-5 was the key to avoid side reactions while keeping a high conversion of cymenes. In the Beckmann rearrangement, neutrality and crystallinity of the pentasil zeolite were keys to obtain a high lactam selectivity, and a high lactam selectivity of 95% was attained by the surface treatment with chlorotrimethylsilane. The active sites were elucidated to be neutral silanols on the external surface of zeolite.     

Sulfonic acid functionalised SBA-15 as catalysts for Beckmann rearrangement and esterification reaction

Hybrid inorganic–organic solid acid materials SBA-15–Ph–SO₃H were synthesized by the directly co-condensation method under the acid medium. The resulting materials perform well both in the liquid phase Beckmann rearrangement (The yield is 32.3%) and esterification reaction (The yield is 95.5%). And more, the catalysts show the different catalytic performance in these two reactions.     

己内酰胺生产中贝克曼转位工艺的改进

通过对己内酰胺生产中贝克曼转位反应机理的研究 ,改进了工艺流程中贝克曼转位反应系统 ,将原设计中的一步转位反应改造成为两步转位反应。改造后工艺数据稳定 ,产品质量提高 ,消耗降低 ,取得了显著的经济效益     

Study the liquid-phase Beckmann rearrangement on the surface of SBA-15-SO<Subscript>3</Subscript>H catalyst

Hybrid inorganic–organic solid acid material SBA-15-Ph–SO₃H was synthesized by the co-condensation of tetraethoxysilane and 2-(4-chlorosulfonylphenyl) ethyltrimethoxysilane in the presence of a Poly (alkylene oxide) block copolymer under acid conditions. The catalytic activity of the obtained materials was studied in liquid-phase Beckmann rearrangement of cyclohexanone oxime to ε-caprolactam. The results show that there exists an obvious “Solvent effect” in this reaction system and the strong Bronsted acid is proofed again to be at the origin of the formation of ε-caprolactam. Moreover, we tentatively proposed a reaction mechanism involving a five-member ring intermediate product when toluene was used as solvent.     

Modification of a heterogeneous catalyst: Sulfonated graphene oxide coated by SiO2 as an efficient catalyst for Beckmann rearrangement

In this work and in continuation of our strategy for improving the performance of heterogeneous catalysts, the SiO₂@GO-OSO₃H catalyst was applied as a very efficient solid acid catalyst for the Beckmann rearrangement. This catalyst effectively catalyzed the liquid-phase Beckmann rearrangement of cyclohexanone oxime to caprolactam in high yield under very mild conditions. The improvement of GO-OSO₃H catalyst in regard to its separation from reaction mixture is achieved by coating it with a mesoporous SiO₂ layer. The influence of the operating parameters on the performance of the catalyst namely solvent, temperature, amount of catalyst, and time was studied.     

Modified Beta Zeolite as Catalyst for Fries Rearrangement Reaction

Modified beta zeolites were applied as catalysts for the Fries rearrangement reaction. The properties of the modified zeolites were characterized by NH₃-TPD, n-hexane and 1,2,4-trimethylbenzene adsorption. Modification with SiO₂ did not block the pores of the beta zeolite but reduced the number of acid sites on the surface. However, when the beta zeolite was modified with Ce₂O₃, the number of acid sites determined by NH₃-TPD increased, which indicated that new acid sites are created by the interaction of cerium oxide and zeolite. Modified beta zeolites and H-beta were applied as catalysts for the Fries rearrangement of phenol acetate. Reaction over H-beta has low selectivity and the catalyst is easily deactivated. SiO₂ modification of the catalyst increases the selectivity of the reaction but decreases the conversion. Ce₂O₃-modified beta zeolites show higher catalytic activity and rearrangement selectivity in the reaction than other catalysts. The stability of the catalyst is also improved after Ce₂O₃ modification. About 70% selectivity and 60-80% conversion can be achieved over 16 wt% Ce₂O₃-modified beta zeolite.     

Theoretical study on vapour phase Beckmann rearrangement of cyclohexanone oxime over a high silica MFI zeolite

We have studied an activation mechanism of cyclohexanone oxime in a cavity of high silica MFI zeolite by using PIO analysis proposed by Fujimoto et al. DFT calculation reveals that the bond length of N–OH becomes longer when water coordinates on oxygen of oxime. The PIO clearly shows out-of-phase interaction between N and O. This out-of-phase interaction is also observed in the PIO of oxime/MFI zeolite cluster model and weakens the N---O bond. Hydrogen bond of Si–OH of nest silanols to oxime is a trigger of vapour phase Beckmann rearrangement.     

扁柏醇合成工艺研究

以普通化工原料CPD(环戊二烯)和NaH为原料,经Wurtz取代反应、【2+2】环加成反应和Beckmann重排反应三步骤合成高纯度扁柏醇,反应条件温和,原料廉价易得,经检测纯度可稳定达到99.8%左右。该方法优于其它反应步骤较多、合成条件苛刻的全合成工艺和传统提取工艺,可实现工业大规模生产。     

Beckmann rearrangement of cyclohexanone oxime over Silicalite-1: an FT-IR spectroscopic study

The study of cyclohexanone oxime (CEOX) adsorption and reaction into -caprolactam (CPL) by FT-IR spectroscopy was performed with Silicalite-1 (S-1) as a catalyst. Information of both active sites and reaction mechanism of the Beckmann rearrangement was obtained. At low temperature the physical sorption of CEOX on/in S-1 is the most relevant phenomenon. The accessibility of the internal OH’s to the reactant increases at higher temperatures due to an easier diffusion. At 200 °C CEOX molecules present inside the zeolite are in proximity of the most acidic OH groups of S-1, the OH nests. The co-operation of more than one OH site transforms CEOX into -CPL, allowing the right reactant-active site configuration and favouring the stabilisation of the intermediate.     

Enhancement effect of organic additives on liquid-phase production of ε-caprolactam

The effect of various organic additives on the catalytic performance of zeolites and Al-containing MCM-41 in the liquid-phase Beckmann rearrangement of cyclohexanone oxime was investigated at 130 °C using benzonitrile as solvent. Over USY zeolite with a large amount of extraframework aluminum (EFAL), the lactam yield was dramatically improved, up to 82%, by adding ethanol, dimethyl sulfoxide, ammonia, diethylamine, or pyridine to the oxime solution. It is due to a selective adsorption of these additives on the detrimental hydrolysis sites as suggested by FTIR results. On the other hand, the additives enhanced both the oxime conversion and the lactam yield through a promotion of the desorption of lactam product from acid sites when beta zeolite and Al-MCM-41 with relatively low EFAL content were used as catalysts.     

Beckmann rearrangement of cyclohexanone oxime in a microchemical system: The role of SO3 and product inhibition

The mechanism of Beckmann rearrangement of cyclohexanone oxime in oleum is investigated with a multiphase microchemical system, which is designed to give good control of the reaction temperature and residence time. The influences of SO₃ and caprolactam concentrations in oleum on the conversion are investigated. The results indicate that SO₃ acts as the catalyst and caprolactam plays a product inhibition role. Based on these results and previous mechanism analysis, an equilibrium relation between protonated caprolactam and caprolactam hydrogen sulfate is proposed and the equilibrium constants at 70, 80, and 90^°C are gained. According to the equilibrium, the lowest acid/oxime molar‐ratio of 0.5 for sufficient conversion (>99%) at 100^°C has been provided. This quantitative mechanism analysis gives the reason for the negative influences of higher caprolactam concentration and lower temperature on the reaction conversion, which is very useful for the optimization and reliable design of Beckmann rearrangement processes. © 2011 American Institute of Chemical Engineers AIChE J, 58: 3156–3160, 2012     

离子液体在环己酮肟Beckmann重排反应中的研究进展

己内酰胺（CPL）是一种重要的有机化工原料。传统的环己酮肟贝克曼（Beckmann）重排法制备己内酰胺是以发烟硫酸为催化剂的生产工艺,存在污染环境、腐蚀设备、能源浪费等不足。基于绿色化工理念,本文综述了离子液体用于环己酮肟贝克曼重排反应合成己内酰胺的研究进展,重点阐述了离子液体作为溶剂、催化剂和反应物3种作用方式在Beckmann重排反应中的最新应用,同时针对离子液体与产物分离困难的问题,讨论了目前文献中的解决方法。在此基础上,分析了离子液体用于Beckmann重排反应在未来的研究方向,并指出设计适宜的离子液体结构、调变酸性性能、降低CPL在离子液体中的溶解度是今后的研究重点。     

环己酮肟Beckmann 重排反应微观混合的数值模拟

采用涡流卷吸-变形-扩散模型,结合反应动力学,对环己酮肟Beckmann重排反应微观混合进行了数值模拟,讨论了工业重排过程中关键工艺参数对反应和传质的影响。结果表明,重排反应过程受微观混合控制,从理论上解释了环己酮肟Beckmann重排最小理论酸量与实际生产值的差异。温度的上升有利于分子扩散的进行,但宏观上造成产品质量下降;反应混合器喷嘴直径适当的减小可提高微观混合的效果,有利于改善传质效果和保证成品质量。     

Performance of modified H-ZSM-5 zeolite for dehydration of methanol to dimethyl ether

The conversion of methanol to dimethyl ether was carried out over various commercial zeolites and modified H-ZSM-5 catalysts to evaluate their catalytic performance. A series of commercially available zeolite samples were used for vapor-phase dehydration of methanol to DME. Catalyst screening tests were performed in a fixed-bed reactor under the same operating conditions (T = 300 °С, P = 16 barg, WHSV = 3.8 h⁻¹). It was found that all the H-form zeolite catalysts in this study were active and selective for DME synthesis. According to the experimental results MDHC-1 catalyst exhibited the highest activity in dehydration of methanol.After finding the most active catalyst, the H-MFI90 zeolite was modified with Na content varying from 0 to 120 mol%, via wet-impregnation method to further improve its selectivity. All of catalysts were characterized by BET, XRD, NH₃-TPD, ICP, TGA, SEM, FT-IR and TPH techniques. It was found that these materials affected activity of MDHC-1 zeolite by changing its acidity. Ultimately, among all the catalysts studied, Na₁₀₀-modified H-MFI90 zeolite exhibited optimum activity, selectivity and stability at methanol dehydration reaction.