Kinetics of glycolysis of poly(ethylene terephthalate) waste powder at moderate pressure and temperature

The reaction of poly(ethylene terephthalate) waste (PETW) powder with ethylene glycol (EG) was carried out in a batch reactor at 2 atm of pressure and a 220°C temperature. The particle size range of 50–512.5 μm and the reaction time of 40–180 min that are required for glycolysis of PETW were optimized. To avoid the carbonization and oxidation of reactants and reaction products and to reduce corrosion, the reaction was undertaken below 250°C using a lower reaction time. To increase the yield of dimethyl terephthalate and EG, an external catalyst was introduced during the reaction. The degree of depolymerization of PETW was proportional to the reaction time. The reaction rate was found to depend on the concentrations of liquid EG and of ethylene diester groups in the polyester. A kinetic model was used for the reaction was found to be consistent with experimental data. The rate constant was inversely proportional to the reaction time, as well as the particle size, of PETW. The degree of depolymerization of PETW was inversely proportional to the particle size of PETW. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1569–1573, 2003     

Production of agrochemical from waste polyesters

In this study, agrochemical was produced from waste polyesters. Reactions of waste polyesters [poly (ethylene terephthalate) (PET) and poly (butylene terephthalate) (PBT)] powder with ethylene glycol (EG) in the presence of tetrahydrofurane (THF) using 0.003 mol lead acetate as a catalyst were carried out in a batch reactor at 470 K and at atmospheric pressure conditions. Reactions were undertaken with various particle size ranges from 50 to 512.5 μm, and reaction time from 30 to 70 min for reactions of polyesters. Low molecular weight product of polyester was obtained during this process. In the next stage, hydroxylamine hydrochloride (HAHC), cyclohexylamine (CHA), and potasium hydroxide (KOH) solution were introduced to convert low molecular weight product of polyester into terephthalohydroxamic acid (TPHA) by introduction of HCl (Hydrochloric Acid) as per stoichiometric requirement. TPHA can be used as an agrochemical (insecticide) with appreciable efficiency. To increase the polyester conversion rate, external catalyst (0.003 mol lead acetate) was introduced during the reaction. The product was deposited on the surface of unreacted polyester, which was removed from the surface by introducing dimethyl sulfoxide (DMSO). To accelerate the reaction rate, DMSO, CHA, and THF were introduced during the reaction, which has an industrial significance. Depolymerization of polyester was proportional to the reaction time. Depolymerization of polyester was inversely proportional to the particle size of polyester. Analyses of value‐added product (TPHA) and byproducts [EG and BD (1,4‐butanediol)] as well as polyesters were undertaken. A kinetic model is developed, and experimental data simulated with it, which was consistent with the model. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2504–2510, 2006     

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     

Chemical Kinetics,Simulation, and Thermodynamics of Glycolytic Depolymerization of Poly(ethylene terephthalate) Waste with Catalyst Optimization for Recycling of Value Added Monomeric Products

Reaction of poly(ethylene terephthalate) (PET) waste powder with ethylene glycol (EG) was carried out in a batch reactor at 1 atm pressure and at various temperatures ranging from 100–220 °C at the intervals of 10 °C. Particle size from 50–512.5 μm, reaction time from 30–150 min, amount of catalyst from 0.001–0.009 mol, and type of catalysts required for glycolysis of PET were optimized. To increase the PET weight (%) loss, various external catalysts were introduced during the reaction at different reaction parameters. Depolymerization of PET was increased with reaction time and temperature. Depolymerization of PET was decreased with increase in the particle size of PET. Reaction rate was found to depend on concentrations of liquid ethylene glycol and ethylene diester groups in the polyester. Analyses of value added monomeric products (DMT and EG) as well as PET were undertaken. Yields of monomers were agreed with PET conversion. A kinetic model was proposed and simulated, and observed consistent with experimental data. Comparisons of effect of various amounts of catalysts and type of catalysts on glycolysis rate were undertaken. Dependence of the rate constant on reaction temperature was correlated by Arrhenius plot, which shows activation energy of 46.2 kJ/mol and Arrhenius constant of 99 783 min^?1.

Arrhenius plot of the rate constant of glycolysis at 1 atm pressure for 127.5 μm PET particle size (KZA = rate constant using zinc acetate as a catalyst, KMA = rate constant using manganese acetate as a catalyst).     

Recycling of off‐grade pet via partial alcoholysis to synthesize functionalized pet oligomer nanocomposites

Off‐grade poly(ethylene terephthalate) (PET) of industrial manufacturers was partially depolymerized using excess ethylene glycol in the presence of manganese acetate as a transesterification catalyst to synthesize PET oligomers. Influences of reaction time, Ethylene Glycol (EG)/PET molar ratio, catalyst concentrations, and particle size of off‐grade PET on yield of partial glycolysis reaction were investigated based on Box–Behnken's design of experiment. Thermal analyses of glycolyzed products are examined by differential scanning calorimetry. The optimum samples were also well‐characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy (¹H‐NMR and ¹³C‐NMR). The optimal conditions to synthesize PET oligomer (melting point of about 180°C) for a 120‐min glycolysis reaction time were EG/PET molar ratio of 2 with no catalyst using granule‐shaped PET. The same results were obtained for a 60‐min glycolysis reaction time, including EG/PET molar ratio of 1 with the weight ratio (catalyst to PET) of 0.5% using average particle size of PET. Then, maleated PET as a compatibilizer for preparing PET nanocomposites was produced via reaction between maleic anhydride/phthalic anhydride composition and optimized PET oligomers based on central composite design of experiment. The combination of reaction time of 106 min and PhA/MA molar ratio of 0.85 gave the best results based on d‐spacing and peak shift of nanocomposite samples. Hence, melt mixing of maleated PET with organoclay produced a good intercalation of layered silicate and good dispersion of clay in maleated PET matrix. Analysis of variance (ANOVA) was studied for both glycolyzed products and functionalized PET oligomers. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Kinetics of glycolysis of poly(ethylene terephthalate) under microwave irradiation

The glycolysis of poly(ethylene terephthalate) (PET) was carried out using excess ethylene glycol (EG) in the presence of zinc acetate as catalysts under microwave irradiation. The effects of particle size, microwave power, the weight ratio of EG to PET, the weight ratio of catalyst to PET, reaction temperature and stirring speed on the yield of bis(hydroxyethyl terephthalate)(BHET) were investigated. The experimental results indicated that the glycolysis rate was significantly influenced by stirring speed and initial particle size. The optimal parameters of glycolysis reactions were the weight ratio of catalyst to PET of 1%, the weight ratio of EG to PET of 5, 500 W and 196°C, the yield of BHET reached to 78% at only 35 min. The glycolysis products were analyzed and identified by FTIR, differential scanning calorimetry, and elemental analysis. The kinetics of glycolysis of PET under microwave irradiation could be interpreted by the shrinking core model of the film diffusion control. The apparent activation energy was evaluated using the Arrhenius equation and it was found to be 36.5 KJ/mol, which was lower compared to the same process using conventional heating. The experimental results also showed that the reaction time was significantly decreased under microwave irradiation as compared with it by conventional heating. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Poly(ethylene naphthalate) formation 1. transesterification of dimethylnaphthalate with ethylene glycol

The transesterification of dimethyl naphthalate (DMN) with ethylene glycol (EG) was kinetically investigated in the presence of various catalysts at 185 °C. The transesterification was assumed to obey first-order kinetics with respect to DMN and EG, and a rate equation was derived. The rate constant of transesterification which calculated from the quantity of methanol distilled from the reaction vessel was used to evaluate each metal compound in its activity. The first-order dependence on the catalyst concentration is valid below a critical concentration which was found to be dependent on the catalyst type. The order of decreasing catalytic activity of various metal ions was found to be: Pb Zn > Co > Mg > Ni Sb. But in the case of highly basic metal salts, the rate constants were found to be extremely large at the initial stage of the reaction, and then rapidly decreased with the progress of the reaction. Effects of reaction temperature were also discussed. The activation energies for zinc acetate and lead acetate were 97.84 and 97.2 KJ/mol, respectively, which were calculated from Arrhenius equation.     

Synthesis of unsaturated polyester resin from postconsumer PET bottles: Effect of type of glycol on characteristics of unsaturated polyester resin

Postconsumer PET bottles including water and soft‐drink bottles were depolymerized by glycolysis in excess glycols, such as ethylene glycol, propylene glycol, and diethylene glycol, in the presence of a zinc acetate catalyst. The obtained glycolyzed products were reacted with maleic anhydride and mixed with a styrene monomer to prepare unsaturated polyester (UPE) resins. These resins were cured using methyl ethyl ketone peroxide (MEKPO) as an initiator and cobalt octoate as an accelerator. The physical and mechanical properties of the cured samples were investigated. It was found that the type of glycol used in glycolysis had a significant effect on the characteristics of the uncured and cured UPE resins. Uncured EG‐based UPE resin was a soft solid at room temperature, whereas uncured PG‐ and DEG‐based resins were viscous liquids. In the case of the cured resins, the EG‐based product exhibited characteristics of a hard and brittle plastic, while the PG‐based product did not. The DEG‐based product exhibited characteristics of hard and brittle plastic after strain‐induced crystallization had occurred. In addition, it was also found that no separation of the type of bottles was needed before glycolysis, since UPE resins prepared from water bottles, soft‐drink bottles, and a mixture of both bottles showed the same characteristics. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 788–792, 2003     

PET废丝常压醇解工艺研究

以乙二醇(EG)为降解剂,以醋酸锌为催化剂对聚对苯二甲酸乙二醇酯(PET)废丝进行醇解,研究了在常压下醇解反应条件对醇解率、醇解产物回收率的影响,对醇解产物进行了红外(IR)、热重-差示扫描量热(TG-DSC)以及扫描电子显微镜(SEM)分析.结果表明:PET废丝在常压下进行醇解反应,当EG:PET废丝:醋酸锌质疑比为...     

环氧乙烷嵌入乙酸乙酯合成(低聚)乙二醇乙醚乙酸酯

探索了在特殊酸/碱双活性位催化剂催化下环氧乙烷(EO)嵌入乙酸乙酯(EA)合成(低聚)乙二醇乙醚乙酸酯(EGEEA)的一步法反应,经红外光谱、电喷雾质谱鉴定得到了预期产物。气相色谱测定结果表明,催化剂AB-5具有较高的单EO选择性,在催化剂用量为1.1 g/100 g EA,体系初压0.1 MPa,反应温度145~150℃,n(EA)∶n(EO)=51∶,EO加料速度为0.25 g/m in的优选条件下,单EO选择性达到w(EGEEA)=51.5%。     

中温型SIPE合成方法

讨论了在间苯二甲酸双羟乙酯 -5 -磺酸钠 ( SIPE)合成反应中催化剂体系、EG/SIPM(间苯二甲酸二甲酯 -5 -磺酸钠 )摩尔比、反应终温和转化率等因素对 SIPE反应过程及产品质量的影响 ,并介绍了中温型 SIPE的合成方法。实验结果表明 ,当 EG/SIPM摩尔比为 3～ 7,选择醋酸盐复合催化剂及相对加入量为 2 0时 ,SIPE合成反应可在终温 175℃完成 ,且产品质量指标优异。高效液相色谱 ( HPL C)测定结果表明 ,实际转化率除与甲醇流出量有关外 ,还与反应温度有关     

高效催化剂在聚酯合成中的应用研究

选择乙二醇锑以及至少一种锰、锌、钴、铅等金属醋酸盐共同组成高效聚酯催化剂体系 ,研究其对缩聚反应的催化作用。实验证明 ,高效催化剂可明显加快缩聚反应速度 ,制得质量合格的PET切片。通过添加碱金属醋酸盐即可改善PET切片色泽 ,碱金属醋酸盐离子浓度 4.5～ 9μg/g较为合适 ,不需添加光学增白剂     

Alkali decomposition of poly(ethylene terephthalate) with sodium hydroxide in nonaqueous ethylene glycol: A study on recycling of terephthalic acid and ethylene glycol

Pellets of poly(ethylene terephthalate) (PET; 0.48–1.92 g) were heated in anhydrous ethylene glycol (EG; 5 mL) with 2-equivs of NaOH at 150°C for 80 min or 180°C for 15 min to convert them quantitatively to disodium terephthalate (Na₂-TPA) and EG. The disodium salt was precipitated quantitatively in pure state from the EG solution and separated readily. The other product EG, being the same component to the solvent, remains in the solution and can be obtained after distillation as a part of the solvent. The rate of decomposition was significantly accelerated by the addition of ethereal solvents to EG, such as dioxane, tetrahydrofuran, and dimethoxyethane. The reaction system is simple; no water and no extra reagent other than NaOH and EG are used. A few recycling systems of PET can be designed on the basis of the present alkali decomposition reaction. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 595–601, 1997     

Über die katalytische wirkung des calciumacetats und des gemisches mangan-natriumacetat bei umesterung von dimethylterephthalat mit äthylenglykol

The products of the ester exchange of DMT with EG in the presence of two catalysts (calcium acetate and a mixture of manganese and sodium acetate) obtained under manufacturing conditions have been investigated. The ester exchange product and the distillate obtained during different reaction times were analysed. On the base of the obtained results of the effect of the duration and temperature the reaction was established as well as of the type of catalyst on the progress of the fundamental and by-reactions. It was found that the trans-esterification proceeds through a mixed ester of terephthalic acid, namely methylethylolterephthalate. After the trans-esterification of the methylester groups of methylethylolterephthalate and DMT the reaction does not stop, but continues with the oligomerization of the diethylterephthalate. At the end of the process about 82% of oligomers are obtained when the catalyst is calcium acetate and 93% with the mixed catalyst. The experimental results show that part of the initial monomers participate in undesired side-reactions (by-processes): hydrolysis of DMT to terephthalic acid and breaking down of EG to acetaldehyde. The results obtained indicate the greater effectiveness of the mixed catalyst.     

油酸改性MPA山梨醇树脂的合成与结构表征

以马来海松酸酐 (MPA)和山梨醇 (S)、乙二醇 (EG)、油酸 (OA)制备油酸接技MPA山梨醇树脂 ,研究了原料配比、反应温度、反应时间、催化剂对产品收率的影响。结果表明 :在n(MPA)∶n(S)∶n(EG)∶n(OA) =1 0∶1 0 2∶1 12∶2 1,反应温度为 2 2 0℃ ,反应时间 3 5h ,w (复合催化剂 ) =0 5 %的最佳合成工艺条件下 ,得到产率为 89%、软化点为 48℃的产品 ,最后用FTIR、1H NMR、TGA、DSC等测试技术 ,确认产品为油酸MPA山梨醇树脂 ,它具有良好的耐热性能。     

LDO的制备及在EGEEA一步法合成中的应用

采用共沉淀法制备了水滑石Mg6Al2(OH)16CO3·4H2O(LDH),煅烧得到镁铝层状复合氧化物（LDO）。X射线衍射(XRD)和热分析(DSC)等结果表明,LDO具有较好的结晶度和良好的热稳定性,表面带有碱性活性中心,可作为一步法合成乙二醇单乙醚醋酸酯（EGEEA）的催化剂。对反应条件进行优化,所得最佳工艺条件为：n(乙酸乙酯)∶n(环氧乙烷)=4∶1,反应温度135 ℃,催化剂用量为环氧乙烷质量的4%,反应时间60 min,体系初压0.9 MPa,在此条件下EGEEA收率为39.21%。     

酯交换法制备二丙烯酸乙二醇酯的研究

以丙烯酸甲酯(MA)与乙二醇(EG)为原料,采用酯交换法合成出了二丙烯酸乙二醇酯(EGDA),对合成反应中的主要条件进行了实验研究。结果表明,适宜的合成条件为:MA与EG物质的量之比为5∶1,且1 mol EG使用9 g对甲苯磺酸为催化剂,由对甲氧基苯酚与吩噻嗪按等质量比复配而成的复合阻聚剂14~16 g,空气通入速度为15 mL/m in,在此条件下合成的粗酯中EGDA含量为83.9%。粗酯经减压精馏后,EGDA产品纯度达99.9%以上。     

聚氨酯用二聚酸聚酯二醇的合成

研究了以辛酸亚锡为催化剂、二聚酸（DA）与乙二醇（EG）为原料、制备聚氨酯用二聚酸聚酯二醇的方法,讨论了催化剂的类型和用量、反应温度、原料醇酸比、反应时间等对酯化率的影响,并用红外光谱对合成产物进行了表征。结果表明,DA与EG摩尔配比为1：2．4,催化剂辛酸亚锡用量为原料总质量的0．3％,反应温度在1h内缓慢升温到190℃,然后保温反应4h,并在130℃、2．66kPa下减压3h,酯化率可达99．7％,产品羟值为95mgKOH／g,酸值0．26mgKOH／g。     

Effect of Surface Activation Treatment on Pt/C Catalyst for Electrooxidation of Ethylene Glycol and Adsorbed CO

It was reported for the first time that the electrocatalytic activity of the Pt/C electrode for the oxidation of ethylene glycol (EG) could be dramatically improved after the new surface treatment of the Pt/C electrode. It was also found that the surface treatment of the Pt/C electrode could greatly promote the electrooxidation of CO adsorbed on the Pt/C electrode. Promoting the electrooxidation of CO would lead to the acceleration of the electrooxidation of EG because CO is an intermediate product of the oxidation of EG and it would be strongly adsorbed on the Pt catalyst, leading the poison of the Pt/C catalyst.     

镁铝复合氧化物催化合成醇醚醋酸酯的研究

介绍了以环氧乙烷、乙酸乙酯为原料,水滑石所衍生的镁铝复合氧化物作催化剂,一步合成乙二醇单乙醚醋酸酯的方法。对其反应条件进行优化,得到适宜的工艺条件:n(乙酸乙酯):n(环氧乙烷)=4:1,反应温度135℃,催化剂用量为环氧乙烷质量的4％,反应时间60min,体系初压0.9MPa,在此条件下乙二醇单乙醚醋酸酯收率为39.21％。