聚酯切片中端羧基含量与工艺操作条件的关系

通过对生产数据的分析并结合生产经验，总结了工艺操作条件与聚酯切片中端羧基含量间的关系，指出生产低端羧基聚酯切片，应严格控制ＤＭＴ，ＥＧ酸值及含水量，降低酯交换催化剂用量，适当增加稳定剂量，缩聚温度应控制在２８５～２８７℃，生产负荷不低于９５％，总停留时间不大于８．４ｈ。     

硫酸钙晶须催化合成醋酸正丁酯

以醋酸正丁酯的合成作为典型的酯合成反应,考察了硫酸钙晶须在酯合成中的催化性能。酯化产率受反应物摩尔比、催化剂用量、反应时间、带水剂、催化剂重复使用次数的影响。实验结果表明,以硫酸钙晶须为催化剂合成醋酸正丁酯时,产率可以达到91%以上。得出了最佳反应条件:冰醋酸与正丁醇的摩尔比为1.1:1,催化剂硫酸钙晶须的量为醇质量的3%,反应时间6h,带水剂甲苯的量为醇质量的14.8%。且催化剂重复使用次数几乎不影响其催化性能。     

Recycling of waste PET‐bottles using dimethyl sulfoxide and hydrotalcite catalyst

The degradation of PET bottles has been successfully achieved using hydrotalcite as catalyst and dimethyl sulfoxide (DMSO) as solvent. The reaction was carried out at boiling point of DMSO (190°C) and degradation was complete in 10 min. The oligomer (tetramer) obtained was treated with NaOH at room temperature in methanol to get dimethyl terephthalate (DMT) and ethylene glycol (EG). Thus, it is a safe and cleaner process. Oligomer was characterized by MS, 13 C‐NMR, X‐ray diffractometric, and thermogravimetric analysis. DMT and EG were characterized by GC‐MS. DMT was also characterized by FT‐IR. GC‐MS analysis shows that the purity of DMT was 99%. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012     

酯化法合成对苯二甲酸二(β-羟乙基酯)的研究

以对苯二甲酸和乙二醇为原料,采用自制催化剂合成出了对苯二甲酸二(β-羟乙基酯)(BHET).最佳反应条件:1 mol对苯二甲酸使用0.2 g催化剂,醇酸摩尔比为12∶1,反应时间为10h,反应温度为185℃.粗品经结晶、重结晶可得质量分数＞99％的BHET产品.     

废对苯二甲酸综合回收利用的优化工艺研究

研究了以废对苯二甲酸(PTA含量85%～95%)与甲醇为原料,对甲苯磺酸为催化剂,催化酯化得到对苯二甲酸二甲酯(DMT)。通过正交实验法优化得到最佳反应条件为:50 mmol的废PTA,催化剂量为0.5 g,反应温度为130℃,甲醇用量为130 mL。在此反应条件下DMT平均酯化率达到(83.1±2.3)%,产物经纯化后DMT纯度达99.5%以上。     

Chemical Degradation of Poly(Ethylene Terephthalate)

The possibility of converting polyethylene terephthalate (PET) waste into terephthalic acid as a primary material by using different techniques through trans-esterification, with an alcohol and through hydrolysis in basic medium, has been investigated. In addition, utilization of activating agents such as inorganic salts and phase transfer catalysts has been investigated.Mineral water and beverage bottles were collected, cleaned and crushed into flakes suitable for the intended experiments. Also, the main products of chemical conversion of such wastes were isolated and confirmed by authentication with standard terephthalic acid through Thin Layer Chromatography (TLC) technique. The reaction yield % was determined to optimize the corresponding experimental conditions and the obtained results have been presented and discussed.     

1-硝基环己烯的合成方法改进

环己醇在以浓硫酸和磷酸组成的混合酸催化作用下,脱水得到环己烯,且当混合酸中浓硫酸和磷酸的体积比为1∶2时,环己烯的收率最高;在乙二醇(EG)作用下,亚硝酸钠和碘在乙酸乙酯和水中硝化环己烯得到标题化合物,其结构经1HNMRI、R和元素分析表征。该一锅合成法采用碘-乙二醇/亚硝酸钠替代氯化汞/亚硝酸钠硝化环己烯制备标题化合物,不涉及用碱液对中间产物的处理,也避免了高毒性有机试剂的使用且反应为均相体系,预处理简单方便,产率较高。     

Oligomer production through glycolysis of poly(ethylene terephthalate): effects of temperature and water content on reaction extent

Using ethylene glycol (EG) and post‐consumer poly(ethylene terephthalate) (PET) bottles, monomers and oligomers were obtained through glycolysis catalyzed by zinc acetate. Three reaction temperatures (150, 160 and 170 °C) and water contents (0, 1.0 and 2.0% with respect to the volume of EG) were used as inputs; the extent of depolymerization as the analyzed response formed the basis for a factorial design experiment. The products obtained from PET glycolysis were analyzed using high‐performance liquid chromatography and Fourier transform infrared spectroscopy, and their morphology was evaluated using scanning electron microscopy. The results showed the presence of terephthalic acid, hydroxylated tetramers, bis(hydroxyethyl) terephthalate monomer and dimer, and also oligomers with various molecular weights, water being present in the reaction medium. Statistical analysis (95% confidence) indicated that temperature and water content were significant inputs for glycolysis of PET, with the temperature being much the more important factor. © 2016 Society of Chemical Industry     

Kinetic and thermodynamic study of methanolysis of poly(ethylene terephthalate) waste powder

Depolymerization of poly(ethylene terephthalate) waste (PETW) was carried out by methanolysis using zinc acetate in the presence of lead acetate as the catalyst at 120–140 °C in a closed batch reactor. The particle size ranging from 50 to 512.5 µm and the reaction time 60 to 150 min required for methanolysis of PETW were optimized. Optimal percentage conversion of PETW into dimethyl terephthalate (DMT) and ethylene glycol (EG) was 97.8% (at 120 °C) and 100% (at 130 and 140 °C) for the optimal reaction time of 120 min. Yields of DMT and EG were almost equal to PET conversion. EG and DMT were analyzed qualitatively and quantitatively. To avoid oxidation/carbonization during the reaction, methanolysis reactions were carried out below 150 °C. A kinetic model is developed and the experimental data show good agreement with the kinetic model. Rate constants, equilibrium constant, Gibbs free energy, enthalpy and entropy of reaction are also evaluated at 120, 130 and 140 °C. The methanolysis rate constant of the reaction at 140 °C (10.3 atm) was 1.4 × 10^?3 g PET mol^?1 min^?1. The activation energy and the frequency factor for methanolysis of PETW were 95.31 kJ mol^?1 and 107.1 g PET mol^?1 min^?1, respectively. © 2003 Society of Chemical Industry     

Synthesis of R-(+)-α-lipoic acid

以6,8-二氯辛酸为原料,S-(-)-α-苯乙胺为拆分剂进行拆分反应得到R-(+)-6,8-二氯辛酸;经酯化制得R-(+)-6,8-二氯辛酸乙酯;后经硫化水解一步合成R-(+)-α-硫辛酸。考察了投料比、溶剂、催化剂、温度等条件对产物收率、比旋光度的影响。结果表明：拆分反应较佳条件为n[S-(-)-α-苯乙胺]∶n（6,8-二氯辛酸）=0.45∶1,溶剂为乙酸乙酯;酯化反应较佳条件为催化剂为对甲苯磺酸,反应时间7 h;硫化反应较佳条件为温度为65 ℃;相转移催化剂用量0.4 g,总收率为44.3%。通过红外光谱、比旋光度、核磁共振等对产物和中间产物进行了表征。     

Studies on the formation of poly(ethylene terephthalate): 2. Rate of transesterification of dimethyl terephthalate with ethylene glycol

The transesterification of dimethyl terephthalate (DMT) with ethylene glycol (EG) was kinetically investigated in the presence of various catalysts at 197°C. The reaction was followed by the measurement of the quantity of methanol which distilled from the reaction vessel. This distillation made corrections of reactant and catalyst concentrations necessary. The transesterification was assumed to obey first-order kinetics with respect to DMT and EG, and a rate equation was derived. The reaction was found to be first order in catalyst concentration as well and when this finding was incorporated in the rate equation, excellent agreement between the observed and calculated values was recognized throughout the reaction. The first-order dependence on the catalyst concentration is valid below a critical concentration which was found to be dependent on the catalyst type. Above this concentration a lower reaction order was observed.     

β-二酮铝和β-二酮酯铝催化合成聚对苯二甲酸乙二醇酯

采用对苯二甲酸(TPA)和乙二醇(EG)为原料,以自制的β-二酮铝和β-二酮酯铝为催化剂经酯化、缩聚,制得聚对苯二甲酸乙二醇酯(PET).探讨了反应条件对合成反应的影响.结果表明:β-二酮酯铝和乙酰丙酮铝优于其他β-二酮铝.EG与TPA的摩尔比为1.2∶1、催化剂的用量为0.5%(与TPA的摩尔比),酯化反应温度为26...     

Palm fatty acid biodiesel: process optimization and study of reaction kinetics

The relatively high cost of refined oils render the resulting fuels unable to compete with petroleum derived fuel. In this study, biodiesel is prepared from palm fatty acid (PFA) which is a by-product of palm oil refinery. The process conditions were optimized for production of palm fatty acid methyl esters. A maximum conversion of 94.4% was obtained using two step trans-esterification with 1:10 molar ratio of oil to methanol at 65°C. Sulfuric acid and Sodium hydroxide were used as acid and base catalyst respectively. The composition of fatty acid methyl esters (FAME) obtained was similar to that of palm oil. The biodiesel produced met the established specifications of biodiesel of American Society for Testing and Materials (ASTM). The kinetics of the trans-esterification reaction was also studied and the data reveals that the reaction is of first order in fatty acid and methanol (MeOH) and over all the reaction is of second order.     

多钒取代磷钼杂多酸的阻聚、催化性质研究

通过酯交换反应合成了甲基丙烯酸异丁酯,并对反应条件进行优化;通过差式扫描量热法测定了磷钼钒杂多酸对甲基丙烯酸甲酯的阻聚性能,结果表明,随着杂多酸结构中钒钼比例数的增大、杂多酸用量的增加以及升温速率的提高,杂多酸的阻聚性能增强,且Dawson型杂多酸的阻聚性能高于Keggin型。在合成甲基丙烯酸异丁酯的反应中,经正交试验得到的最优反应条件为:醇酯物质的量比为1.2∶1,Dawson型磷钼钒杂多酸-V6催化剂(Dawson-V6)用量为反应物总质量的8%,反应时间7.5 h,磷钼钒杂多酸对不饱和酯的合成具有催化作用和较好的阻聚效果。     

A new process for catalyst-free production of biodiesel using supercritical methyl acetate

Production of glycerol is unavoidable in the conventional processes for biodiesel fuel (BDF) production. In this research, therefore, we investigated conversion of rapeseed oil to fatty acid methyl esters (FAME) and triacetin (TA) by processing of supercritical methyl acetate. As a result, it was discovered that the trans-esterification reaction of triglycerides with methyl acetate can proceed without catalyst under supercritical conditions, generating FAME and triacetin. In order to study the effect of the triacetin addition to FAME, its effect was investigated on various fuel characteristics. It was, consequently, discovered that there were no adverse effects on the main fuel characteristics when the molar ratio of methyl oleate to triacetin was 3:1, corresponding to the theoretically derived mole ratio from the trans-esterification reaction of rapeseed oil with methyl acetate. Moreover, the addition of triacetin to methyl oleate improved the pour point and triacetin has high oxidation stability. Therefore, by defining BDF as a mixture of methyl oleate with triacetin, we can obtain an improved yield of 105% of BDF by the supercritical methyl acetate, in excess of the yield of the conventional process.     

SO42-/TiO2催化合成乙酸环己酯

以固体超强酸SO4^2-／TiO2催化乙酸和环乙醇合成了乙酸环己酯。实验确定最佳反应条件为n（乙酸）：n（环己醇）：1．0：1．2，SO4^2-／TiO2用量为乙酸质量的10％，反应时间90min，酯化率达92．3％，并与其它催化剂作了比较，结果表明，以SO4^2-／TiO2为催化剂，具有催化剂量少、重复使用效果好、反应时间短、酯收率高、方法简单等优点。     

In situ ester–amide exchange reaction between polyamide 6 and ethylene‐vinyl acetate rubber during melt blending

The ester–amide exchange reaction between polyamide 6 (PA6) and ethylene‐vinyl acetate rubber (EVM) with dibutyltin oxide (DBTO) as a catalyst took place during melt blending, leading to the formation of PA6‐grafted EVM copolymer (EVM‐g‐PA6) and acetamide‐terminated PA6. The exchange reaction extent, expressed by the percentage content of the acetate groups taking part in the exchange reaction, was 5.9 mol %, and the yield of EVM‐g‐PA6 copolymer was 6.8 wt % for PA6/EVM/DBTO (60/40/1) blend at 230°C for 60 min. The number‐average molecular weight of PA6 branches in EVM‐g‐PA6 was ～278 g/mol as evaluated from nuclear magnetic resonance spectra. The reaction kinetic parameters were calculated according to a second‐order reversible reaction mechanism. The rate constant was dependent on the catalyst concentration, PA6/EVM ratio, and shearing conditions. In this article, the characterized ester–amide exchange reaction between PA6 and EVM will guide the fabrication of novel EVM‐based graft copolymers and high‐performance PA6/EVM thermoplastic elastomers for engineering applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40272.     

间苯二甲酸双羟乙酯-5-磺酸钠的合成研究

采用间苯二甲酸二甲酯-5-磺酸钠(SIPM)和乙二醇(EG)为原料,在一定的温度和催化剂条件下进行酯交换反应制备间苯二甲酸双羟乙酯-5-磺酸钠(SIPE)。用高效液相色谱(HPLC)法测定酯交换率,系统研究了催化剂、EG／SIPM摩尔比及反应时间对酯交换率的影响。     

超声微波耦合催化合成蔗糖脂肪酸酯

通过超声微波耦合作用,采用无溶剂法制备蔗糖脂肪酸酯,研究催化剂类型、催化剂用量、超声微波功率、酯糖物质的量比和反应温度对蔗糖脂肪酸酯产率的影响。结果表明,超声微波耦合对蔗糖与脂肪酸甲酯的酯交换反应具有良好的促进作用,超声微波耦合作用下,蔗糖和脂肪酸甲酯能够形成较为良好的乳化状态。有机钛催化剂对蔗糖与脂肪酸甲酯的酯交换反应具有极佳的催化性能,与碱催化剂相比,具有用量少和活性高的特点。以钛酸四异丙酯为催化剂,在超声微波耦合体系中,蔗糖脂肪酸酯最高产率可达86.6%,其中,产品单酯含量为92.7%。     

对苯撑二（4-氨基苯并恶唑）合成工艺的正交试验

用对苯二甲酸、2,4-二氨基苯酚盐酸盐为原料合成了对苯撑二（4-氨基苯并恶唑）。采用正交试验方法讨论了原料配比、反应时间、反应温度和催化剂的用量对产品收率的影响,并得出了优选反应工艺条件为：物料配比为n（2,4-二氨基苯酚盐酸盐）：n（对苯二甲酸）=2.1;反应时间为7h;反应温度为210℃;n（多聚磷酸）：n（对苯二甲酸）=1.5,在此条件下产品的收率可以达到87%以上,经精制后产品的纯度可以达到99.4以上。