Effective promotion of tetrahydrofuran polymerization initiated with heteropolyacid

Tetrahydrofuran was polymerized using the heteropolyacid H₃PW₁₂O₄₀ as the initiator and ethylene oxide as the promoter, which effectively increased the rate and conversion of the polymerization. Water and butylene glycol were used to control the molecular weight of the product in the range of 1000–3000. The polymer was found to be polyether glycol containing 10–22 mol % oxyethylene moieties with hydroxyl groups at both chain ends. The melting point was ∼ 10°C lower compared to polytetramethylene ether glycol having the same molecular weight. The concentration of active species remained unchanged in the main period of the polymerization, indicating the absence of chain termination. The values of the chain propagation rate constant of tetrahydrofuran polymerization at 0 and 20°C were found to be 3.78 × 10⁻³ and 1.98 × 10⁻² L mol⁻¹ s⁻¹, respectively, which are close to the rate constant of chain propagation of tetrahydrofuran on ionic active species. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2303–2308, 1999     

Control of molecular weight in tetrahydrofuran polymerization initiated by heteropolyacid

Both anhydrous and hydrated heteropolyacid can be used to initiate the tetrahydrofuran polymerization in the presence of ethylene oxide promoter, in regard to the crystallization water of the hydrated one as a part of the extra-added water for controlling the molecular weight. The polyether glycol having number-average molecular weight of 2000 ± 100 or 1000 ± 50 was prepared in yield beyond 50% by the process without neutralization or neutralization and washing with water after polymerization, respectively. A modified equation based upon conversion of polymerization and concentrations of molecular weight controller and heteropolyacid with a correction factor for predicting the number-average molecular weight of the product was given. The products were characterized by nuclear magnetic resonance, gel permeation chromatography, and differential scanning calorimetry analyses. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 269–275, 2001     

Tetrahydrofuran polymerization initiated by heteropolyacid in the presence of ethylene oxide: Reaction behavior of water and glycol

The reaction behavior of water and low molecular weight glycol in tetrahydrofuran polymerization initiated by H₃PW₁₂O₄₀ in the presence of ethylene oxide has been studied. A lot of water was used in the hydrolysis reaction of ethylene oxide at the early stage of the polymerization and transformed into ethylene glycol (EG), which was consumed subsequently through a chain transfer reaction. EG was more reactive both than 1,4‐butylene glycol and hexamethylene glycol toward propagating species, and the reaction rate constants at 0°C were determined by GC to be 0.142, 8.83 × 10⁻², and 5.53 × 10⁻² L · mol⁻¹s⁻¹, respectively. The molecular weight of the product can be predicted by an equation based upon conversion of polymerization and the concentrations of molecular weight controller and H₃PW₁₂O₄₀. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1821–1826, 1999     

环氧乙烷/四氢呋喃共聚醚的合成与表征

用杂多酸(HPA)引发环氧乙烷(EO)与四氢呋喃(THF)发生共聚反应,从而制得了EO-THF共聚醚[P(EO-THF)]。用红外光谱(FT-IR)、核磁共振(1H NMR)、凝胶渗透色谱-多角度激光散射仪(SEC/MALLS)和差示扫描量热仪(DSC)等仪器对P(EO-THF)的结构进行了表征,并对其聚合机理进行了分析。实验结果表明,HPA作为引发剂可用来制备相对分子质量分布指数小于1.4、平均官能度为2的P(EO-THF);P(EO-THF)的熔点受单体投料比影响较大,当n(EO)∶n(THF)=1∶1时,产物的熔点最低(为-14.28℃);在共聚反应过程中,THF的浓度对共聚反应速率及P(EO-THF)的相对分子质量影响显著,当THF的浓度小于1.39 mol/L时,共聚反应速率较低。     

Epoxidation of Propylene by Molecular Oxygen over Modified Ag–MoO3 Catalyst

Epoxidation of propylene to propylene oxide by molecular oxygen was studied over a modified Ag-MoO₃ catalyst. The results show that MoO₃ plays an important role in improving the efficiency of the catalyst, and a suitable content of MoO₃ is 40-50 wt%. XPS reveals that some of the silver and molybdenum in the catalyst exist as Ag⁺ and Mo^{(6 - )+}, respectively. The promotion effect of NaCl, Ce(NO₃)₃, BaCl₂ and CsNO₃ on the Ag-MoO₃ catalyst was studied. As a modifier of the Ag-MoO₃ catalyst, NaCl or Ce(NO₃)₃ are more suitable than BaCl₂ or CsNO₃ and the optimal loading of NaCl or Ce(NO₃) is about 2 wt%. Using a feedstock gas of 15.6% C₃H₆, 12.2% O₂ and balance N₂ without any addition of NO, EtCl or CO₂ at a space velocity of 4500 h^-1, 6.8% O₂ conversion and 53.1% selectivity to propylene oxide were achieved over the Ag-MoO₃-2.0% NaCl catalyst at 400 °C. At 450 °C the O₂ conversion and selectivity to propylene oxide were 11.4 and 43.6%, respectively.     

Polymerization of some oxiranes using the diphenylzinc-butanone system in benzene at 60°C

The diphenylzinc-butanone system was used as polymerization catalyst for some oxiranes in benzene solution at 60°C. This system is greatly influenced by the molar ratio of butanone to diphenylzinc, and the maximum catalytic activity for propylene oxide and ethylene oxide was found for a ratio of unity. GPC results strongly suggest the presence of more than one active species for the system. ¹³C NMR analysis indicates that the resulting poly(propylene oxide) has a head-to-tail arrangement. For the polymerization of propylene oxide with butanone/diphenylzinc = 1, after an initial induction period, the reaction was first-order with respect to monomer with k = 2·51 × 10^?5 s^?1. Ethylene oxide polymerizations using butanone/diphenylzinc = 1 and 5 were also first-order with respect to monomer after an initial induction period with k = 7·80 × 10^?6 s^?1 and k = 5·71 × 10^?6 s^?1, respectively. The diphenylzinc-butanone system was not an effective catalyst for styrene oxide polymerization.     

Photoinduced living cationic polymerization of tetrahydrofuran. II: Synthesis of four‐armed star‐shaped poly(tetrahydrofuran)

A four‐armed star‐shaped poly(tetrahydrofuran) (THF) having a pentaerythritol unit at the center of the molecule was synthesized from photoinduced cationic copolymerization of THF and pentaeryithritol tetrakis(3,4‐epoxybutanoate) (PETE) in the presence of diphenyliodonium hexafluorophosphate. It was found that the molecular weight of the resulting polymer increases with increasing percent conversion and the rate of cationic polymerization of THF is remarkably increased by the addition of PETE when the concentration of PETE is kept much lower than that of THF. A similar enhancement effect was also observed in the photoinduced cationic polymerization of THF in the presence of epichlorohydrin (ECH). The enhancement effect of ECH and PETE was ascribed to the increased concentration of the cationic propagating species due to a rapid protonation process. The living nature was explained in terms of the stabilization of the cationic growing chain end by ion pair formation. Accordingly, the arm length of the polymer was determined by the molar ratio of THF and PETE. However, the polymer of well‐defined structure was only obtainable in the early stage of the reaction because chain transfer to the polymer process plays an important role when the concentration of the polymer becomes high. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2637–2644, 1999     

环氧丙烷阴离子聚合——相对分子质量上限及其影响因素

用叔丁醇钾作催化剂,对环氧丙烷进行本体阴离子聚合,设计聚合物的数均相对分子质量为1 000~5 000,用激光光散射和核磁共振测定其相对分子质量,确定了聚环氧丙烷的相对分子质量上限为2 600左右。用在线红外技术跟踪聚合过程,研究环氧丙烷(828 cm-1)、聚醚(1 107 cm-1)、C C双键(1 660 cm-1)的吸光度变化曲线,发现除了链转移反应外,体系中阴离子活性中心失活也会制约相对分子质量增加。     

聚丙烯环管反应器的动力学特征

讨论了聚丙烯环管反应器内聚丙烯反应机理，反应速率；以齐鲁石化公司塑料厂的实际运行数据为基础，建立了物热衡算数学模型；并通过对模型求解，得到了反应器内的聚合速率，固含率在不同产量下随温度的变化规律，通过分析得出其温度的最佳操作域。     

超临界CO2介质中丙烯直接环氧化生产PO研究进展

在Pt-Pd/TS-1催化下,利用H2、O2原位生成的H2O2进行的丙烯环氧化生产环氧丙烷是特别有意义的方法。环氧丙烷的选择性与催化剂的类型、催化剂还原方法、Pd的附载量以及溶剂的种类等有关,在超临界CO2中比在N2或甲醇中选择性高。     

丙烯聚合催化剂进展

本文论述丙烯聚合催化剂发展多相Z-N型经历三代,均相有钛、锫、铪和钒等系。     

过氧化氢及其基本有机化学品绿色合成技术

烃类氧化与氮化反应是生产基础有机化学品和高附加值产品的主要反应,在满足和丰富人类物质需求方面贡献巨大,传统的工业氧化与氮化工艺导致严重的环境问题,亟需绿色化转型。作为公认的绿色氧化剂,过氧化氢在烃类氧化和氮化的绿色生产工艺中应用广泛。文章简要介绍了国内外过氧化氢生产现状,重点介绍了中国石化石油化工科学研究院浆态床过氧化氢生产技术,以己内酰胺、环氧丙烷和环氧氯丙烷为例,介绍了过氧化氢在绿色烃类氧化和氮化反应中的应用,汇报了石油化工科学研究院近年来在绿色化工方面的主要研究进展及工业实践结果。多个成套绿色化工技术的成功开发突破了国外对我国的技术封锁,为多个化工生产基地提供全流程绿色生产技术,有力保障了我国化工行业的绿色化转型。     

Dehydrochlorination of propylene chlorohydrin with sodium hydroxide and with catholyte

Dehydrochlorination of an aqueous solution of propylene chlorohydrin with sodium hydroxide (12·5 and 30% by weight), with catholyte (5 or 10% by weight NaOH + 14% by weight NaCl) and with milk of lime (15% by weight) were compared. The use of catholyte (10% by weight NaOH + 14% by weight NaCl) enables propylene oxide to be obtained in a yield of 94·3%, with 100% conversion of chlorohydrin. The concentration of 1,2-propylene glycol in the waste is 0·07% by weight.     

影响氯丙醇收率的因素与优化控制

根据反应原理并结合生产实践,定性分析、探讨了氯醇法生产环氧丙烷的关键工序———氯醇化工序中影响氯丙醇收率的因素,提出了提高氯丙醇收率的优化控制措施。     

多金属氰化络合物催化环氧丙烷聚合的诱导期研究

通过观察聚合体系的压力与温度变化,分别研究了催化剂用量、引发剂和酸的种类、单体用量和反应温度等因素对环氧丙烷(PO)聚合诱导期的影响规律。研究结果表明,随着催化剂和单体用量的增大以及反应温度的升高,PO聚合诱导期明显缩短;酸对催化剂的激活具有明显的促进作用,可显著缩短聚合诱导期;不同引发剂对聚合诱导期的影响明显不同,聚合诱导期随着引发剂用量的增加而延长。     

有机-无机杂化黏土催化四氢呋喃聚合

采用后合成方法,将γ-巯基丙基三乙氧基硅烷嫁接到黏土表面,获得含磺酸有机功能团的黏土固体酸催化剂。经XRD、N₂ 吸附-脱附、FTIR、吡啶吸附和酸量滴定等物性结构表征及催化四氢呋喃聚合的反应活性评价,结果表明,改性后的黏土保持了原有黏土介孔结构,孔径分布集中在3 ～4.3 nm,酸量增加了35％,在催化四氢呋喃聚合反应中显现出较高的催化活性,在反应温度为35℃、反应时间为8 h的条件下,聚合产物收率达30％,得到数均分子量为2000左右、可用作氨纶生产原料的聚合物。     

低碳烯烃叠合法柴油合成催化剂的研究与探讨

探讨了Fe2/3xNi1-xSO4-助剂/g-Al2O3催化剂对丙烯叠合柴油反应的催化性能.考察了Fe/(Fe Ni) 原子分率和SO2-4/(Fe Ni)摩尔比的影响及加入助剂的效果,发现Fe/(Fe Ni) 原子分率0.72和SO2-4/(Fe Ni)摩尔比在1.2～2.2,催化剂活性和选择性最高.加入助剂P2O5效果较好.通过NaOH对催化剂的中毒及其对催化活性的关联,证明该催化剂上的丙烯叠合反应是以酸催化反应机理进行.     

四苯基铁卟啉仿生催化丙烯环氧化合成环氧丙烷的研究

合成了四苯基铁卟啉并用于催化丙烯环氧化合成环氧丙烷,考察了共还原剂种类、催化剂浓度、共还原剂用量、反应时间、反应温度、反应压力对实验的影响。该反应适宜的条件为1.74×10~(-5)mol/L催化剂TPPFe~(Ⅲ)Cl;1.31×10~(-4)mol/L助催化剂3-吲哚乙酸;共还原剂丙烯醛,n(正丁醛)∶n(丙烯)=1∶1.2;溶剂二氯甲烷,n(二氯甲烷)∶n(丙烯)=15.45;反应温度98℃;反应压力1.65 MPa;反应时间1.8 h。在该条件下,丙烯的转化率为35.04%,环氧丙烷的收率和选择性分别达34.28%和97.83%。