Glycolysis Of Polyethylene Terephthalate Research Articles

Removal of Zn2+ from polyethylene terephthalate (PET) glycolytic monomers by sulfonic acid cation exchange resin

Glycolysis of polyethylene terephthalate (PET) has always been a research hotspot in PET waste recovery due to its high efficiency and sustainability. Zinc acetate (ZnAc2•2H2O) and urea/(ZnAc2•2H2O) are usually regarded as the most promising catalysts for the glycolysis of PET, while the residue of Zn2+ in glycolytic monomers (bis(hydroxyalkyl) terephthalate (BHET)) was identified as a big hassle, which caused the detrimental effect on the chromaticity of down-stream product. However, the removal of Zn2+ from BHET has almost not been reported previously. In the present work, ion exchange was adopted as effective measure to eliminate trace Zn2+ from BHET and more than 99% of Zn2+ can be removed by 001*7 sulfonic acid resin with resin dosage of 1.6 g/L at 298.15 K, 160 rpm for 120 min. Additionally, based on prevailing adsorption kinetics, isotherms, thermodynamic models and various precise instruments, comprehensive adsorption mechanism were exploited. Pseudo-second-order model (R2 > 0.999) and Langmuir model (R2 > 0.999) were found to match well with the experimental data, indicating the sorption of Zn2+ on 001*7 was homogeneous monomolecular layer adsorption and dominated by chemisorption. The thermodynamic model revealed the sorption was thermodynamically spontaneous. Fourier-Transform Infrared Spectroscopy (FTIR) illuminated the sulfonic acid groups on 001*7 resin were the main binding sites for Zn2+. X-ray Photoelectron Spectroscopy (XPS) elucidated ion exchange and electrostatic interaction between the sulfonic acid groups and Zn2+ were responsible for the sorption of Zn2+. All the results obtained can prove 001*7 sulfonic acid resin is an efficient material for removal of Zn2+ from BHET.

Hydrodynamic synthesis of Fe2O3@MoS2 0D/2D-nanocomposite material and its application as a catalyst in the glycolysis of polyethylene terephthalate.

We report a fast and simple synthesis of Fe2O3@MoS2 0D/2D-nanocomposite material using a Taylor–Couette flow reactor. A Taylor–Couette flow with high shear stress and mixing characteristics was used for fluid dynamic exfoliation of MoS2 and deposition of uniform Fe2O3 nanoparticles, resulting in a Fe2O3@MoS2 in the form of 0D/2D-nanocomposite material. Using Taylor–Couette flow reactor, we could synthesize Fe2O3@MoS2 0D/2D-nanocomposite material at a rate higher than 1000 mg h−1 which is much higher than previously reported production rate of 0.2–116.7 mg h−1. The synthesis of Fe2O3@MoS2 nanocomposite was achieved in an aqueous solution without thermal or organic solvent treatment. Exfoliated MoS2 nanosheets show an average thickness of 2.6 ± 2.3 nm (<6 layers) and a lateral size of 490 ± 494 nm. Fe2O3 nanoparticles have an average size of 7.4 ± 3.0 nm. Fe2O3 nanoparticles on chemically and thermally stable MoS2 nanosheets show catalytic activity in the glycolysis of polyethylene terephthalate (PET). High conversion of PET (97%) and a high yield (90%) for bis(hydroxyethyl) terephthalate (BHET) were achieved in a reaction time of 3 h at the reaction temperature of 225 °C.

Synthesis of two-dimensional holey MnO2/graphene oxide nanosheets with high catalytic performance for the glycolysis of poly(ethylene terephthalate)

Two-dimensional (2D) materials have been extensively studied as promising heterogeneous catalysts because of their high surface area, outstanding mechanical strength, and excellent chemical and thermal stability. Herein, we report an efficient and simple two-step strategy for the synthesis of 2D holey and ultrathin MnO2/graphene oxide nanosheets. As a 2D nanoporous support, holey graphene oxide (HGO) nanosheets are prepared by an oxidative etching method. The uniform and conformal deposition of MnO2 onto the HGO surface is performed by a solution-based self-limiting redox reaction, resulting in nanoporous MnO2/HGO nanosheets with a high surface area. The resulting MnO2/HGO shows outstanding catalytic performance for the glycolysis of polyethylene terephthalate (PET). A high conversion of PET (100%) and a high yield of a bis(hydroxyethyl) terephthalate (BHET) are achieved within a short reaction time of 10 min at a reaction temperature of 200 °C. Furthermore, the MnO2/HGO catalyst shows excellent recyclability for the glycolysis of PET; a BHET yield of 100% is obtained after 5 cycles.

Four-factor optimization for PET glycolysis with consideration of the effect of sodium bicarbonate catalyst using response surface methodology

In this study, Response Surface Methodology based on four-factor Box-Behnken design was applied to suggest the optimal conditions for glycolysis of polyethylene terephthalate (PET) and to analyze the individual and interaction effects of the factors on the process. Four independent factors of interest, namely reaction time (3–5 h), reaction temperature (192–200 °C), mass ratio of ethylene glycol (EG) to PET (2.5–7.5), and mass ratio of sodium bicarbonate (NaHCO3) to PET (0.6–1.0%), were under consideration for their catalyst effect on the process. A regression model as a mathematical function of the four factors was obtained to predict the yield of bis(2-hydroxyethyl) terephthalate (BHET) yield and its reliability was evaluated by analysis of variance. A remarkably high yield of 75.7% was obtained with 1.3% error from the predicted value at the optimal operating conditions for temperature, time, EG:PET mass ratio, and NaHCO3:PET mass ratio of 192 °C, 3.02 h, 6.09 and 0.82%, respectively. The experimental results and analysis of response surfaces revealed that an inappropriately large amount of catalyst might restrict monomer conversion under excess EG conditions. Moreover, PET glycolysis process could be carried out under lower temperature and shorter time due to the profound effect of excess EG at a suitable concentration level of NaHCO3. This suggested future in-depth analysis with wider parameter space to optimize PET glycolysis under conditions of large amount of EG and to gain insight into the interaction effect between EG amount and catalyst concentration.

Demulsification of water in heavy crude oil emulsion using a new amphiphilic ionic liquid based on the glycolysis of polyethylene terephthalate waste

Abstract A new amphiphilic ionic liquid (IL) was prepared based on the glycolysis product of polyethylene terephthalate (PET) waste. Bis(2-hydroxyethyl) terephthalate (BHET) produced from glycolysis of PET was converted into bis(2-chloroethyl) terephthalate (BCET). The glycidyl 4-nonylphenyl ether (GNE) was reacted with ethanol amine (EA) to form the corresponding amine, 1-((2-hydroxyethyl)amino)-3-(4-nonylphenoxy)propan-2-ol, (HANP) and the formed amine was then ethoxylated using tetraethylene glycol (TEG) to form ethoxylated amine (EHANP). The EHANP was quaternized by BCET to form the corresponding ionic liquid (EHANP-IL). Following the synthesis, the chemical structure was confirmed by Fourier-transform infrared spectroscopy (FTIR), and proton nuclear magnetic resonance (1H NMR). The surface activity and dynamic light scattering (DLS) properties were also investigated. Further, the demulsification efficiencies of synthesized IL and EHANP was evaluated and found that the EHANP-IL was able to demulsify water-in-oil (W/O) emulsions with high efficiency than that of respective EHANP.

ZnO nanodispersion as pseudohomogeneous catalyst for alcoholysis of polyethylene terephthalate

Chemical depolymerization and recycling of polyethylene terephthalate (PET) is a sustainable way to preserve the resources and protect the environment. In this work, methanol and ethylene glycol dispersions of ultrasmall ZnO nanoparticles are firstly adopted as pseudohomogeneous catalysts for alcoholysis of PET. The as-prepared ZnO nanoparticles have a uniform size of 4 nm and can be stable in dispersions for 6 months. In the methanolysis process of PET, the effects of various parameters on the conversion of PET and the yield of dimethyl terephthalate (DMT) were investigated. The results show that higher temperature (170 °C) was beneficial to the conversion of PET and the yield of DMT, which can reach about 97% and 95% after 15 min, respectively. The excellent activity of 553 g PET h−1 (g ZnO)−1 was achieved. Furthermore, the methanolysis of PET have shorter reaction time (1/4) and higher activity (4.7 times) than the glycolysis of PET.

Chemical Recycling of Polyethlylene Terephthalate by Glycolysis Using Deep Eutectic Solvents

In this study, the glycolysis of polyethylene terephthalate was studied in presence of deep eutectic solvents as catalyst. In the glycolysis of PET, five different deep eutectic solvents were synthesized using different hydrogen bond donors and acceptors. Among the synthesized DESs, the most efficient catalyst was found to be DES formed by potassium carbonate and ethylene glycol. Glycolysis reaction was performed between PET and ethylene glycol. The effects of process parameters such as temperature, ratio of EG/PET and ratio of DES/PET were examined. The maximum yield for monomer product, bis(2-hydroxyethyl) terephthalate was observed as 88% at the reaction temperature of 180 °C, ethylene glycol/deep eutectic solvent ratio of 15 and deep eutectic solvent/polyethylene terephthalate ratio of 6.

Low-Cost Catalyst for Glycolysis of Polyethylene Terephthalate (PET)

A low-cost process for the depolymerization of polyethylene terephthalate (PET) was investigated in this work by the development of catalysts derived from food wastes for the glycolysis reaction of post-consumable waste of drinking bottles. Bis (2-hydroxyethyl) terephthalate (BHET) is obtained as a product from the glycolysis of polyethylene terephthalate (PET). Calcium oxide (CaO) catalysts derived from shells were used in this reaction. The yield of bis (2-hydroxyethyl) terephthalate (BHET) was obtained and the purity of BHET was confirmed by NMR spectroscopy.

PET glycolysis optimization using ionic liquid [Bmin]ZnCl3 as catalyst and kinetic evaluation

Abstract In the present work, the depolymerization of polyethylene terephthalate (PET) was performed by the method of glycolysis with ethylene glycol. The process was carried out using a factorial design in the Box-Behnken optimization model, using a response surface methodology (RSM) in which three factors (time, temperature and mass ratio of ethylene glycol) were studied in three levels of variation (- 1, 0, +1) with two replicates of the center point, totalizing 15 experiments for which the yield of bis (2-hydroxyethyl) terephthalate (BHET) monomers formed in the process was chosen as response. In parallel, the Arrhenius kinetic test was used to determine the apparent activation energy (Ea) for the 1-butyl-3-methylimidazole trichlorozincate ([Bmin]ZnCl3) - catalyst used in the depolymerization process. The products of glycolysis obtained were characterized by spectroscopic techniques (FTIR), (1 H and 13C NMR), thermal analyses (TGA) and (DSC) and Mass Spectrometry LC-MS/MS hybrid Quadrupole-Orbitrap.

Ultrafast Homogeneous Glycolysis of Waste Polyethylene Terephthalate via a Dissolution-Degradation Strategy

Recycling of discarded polyethylene terephthalate (PET) is an important issue for both environmental protection and resource conservation purposes. In this work, a dissolution-degradation strategy has been developed for recycling PET by adding solvents such as aniline, nitrobenzene, 1-methyl-2-pyrrolidinone (NMP), or dimethyl sulfoxide (DMSO) into the traditional PET glycolysis system. The results show that the conversion of PET reaches 100% and the yield of monomer bis(hydroxyalkyl) terephthalate (BHET) reaches 82% during 1 min with zinc acetate as catalyst in DMSO at 463 K. Importantly, this strategy can be applied to a variety of catalysts. The simulation and in situ IR results indicate that the π–π interaction between PET and aromatic solvents plays a key role in PET dissolution, which leads to fast degradation. This promising dissolution-degradation strategy can improve the glycolysis efficiency of PET dramatically and may be applied to the degradation process of other polyesters.

Preparation and Characterization of Polyester Polyol Modified Bitumen for Pavement Applications

In this study, polymer modified bitumen (PMB) from polyester polyols was prepared by bis(2-hydroxyethyl terephthalate) (BHET) which was obtained by glycolysis of Polyethylene terephthalate (PET) waste. The effect of polyester polyol structure on the rheological properties of PMB was investigated. Polyester polyols obtained by the reaction of various polyols and polycarboxylic acids. POL1, synthesized from BHET and adipic acid (AA), were blended with the bitumen resulting in improved stiffness, rutting resistance and fatigue performance with respect to neat bitumen. Also, the synergistic effects of the polyester polyol addition into styrene-butadiene-styrene modified bitumen (SBS-Bitumen) were investigated where this reference mixture contains SBS loading of 3 % according to the weight of bitumen. Although the addition of POL1(1.3:1) into SBS:Bitumen mixture at 3:3:94 weight ratio didn’t alter the high temperature performance grade of PMB, POL1:SBS:Bitumen exhibited higher softening point, elastic recovery and rutting parameter than reference mixture. The early stage promising results of this study indicated the potential benefits of polyester polyol as bitumen modifier. Also, this study showed that the use of BHET obtained by PET waste as a starting material for polyester polyol synthesis could be an alternative way to utilize plastic waste.

Ultrasmall Cobalt Nanoparticles as a Catalyst for PET Glycolysis: A Green Protocol for Pure Hydroxyethyl Terephthalate Precipitation without Water

Polyethylene terephthalate (PET) is a very stable polymer widely used in the modern world. Due to its stability, this polymer can remain in the environment for several years before its complete degradation. The glycolysis reaction of PET has emerged as a green approach to obtain the PET monomer, thus avoiding such environmental problems and adding value to this waste. In this work, PET waste was depolymerized by glycolysis using ultrasmall cobalt nanoparticles (1.5 wt %) as the catalyst for the production of bis-2-hydroxyethyl terephthalate (BHET). A capping agent (tannic acid, TA) and a borohydride reduction approach were used to obtain such ultrasmall cobalt nanoparticles (∼3 nm). A PET depolymerization yield of 96% was achieved within 3 h at 180 °C. The precipitation of 77% of pure BHET was achieved without the need for water. The remaining ethylene glycol solution containing the ultrasmall cobalt nanoparticle catalyst was reused five times for this glycolysis process, demonstrating the feasibility of ...

Solubilization and Upgrading of High Polyethylene Terephthalate Loadings in a Low-Costing Bifunctional Ionic Liquid.

The solubilization and efficient upgrading of high loadings of polyethylene terephthalate (PET) are important challenges, and most solvents for PET are highly toxic. Herein, a low-cost (ca. $1.2 kg-1 ) and biocompatible ionic liquid (IL), cholinium phosphate ([Ch]3 [PO4 ]), is demonstrated for the first time to play bifunctional roles in the solubilization and glycolytic degradation of PET. A high loading of PET (10 wt %) was readily dissolved in [Ch]3 [PO4 ] at relatively low temperatures (120 °C, 3 h) and under water-rich conditions. In-depth analysis of the solution revealed that high PET solubilization in [Ch]3 [PO4 ] could be ascribed to significant PET depolymerization. Acid precipitation yielded terephthalic acid as the dominant depolymerized monomer with a theoretical yield of approximately 95 %. Further exploration showed that in the presence of ethylene glycol (EG), the [Ch]3 [PO4 ]-catalyzed glycolysis of PET could efficiently occur with approximately 100 % conversion of PET and approximately 60.6 % yield of bis(2-hydroxyethyl)terephthalate under metal-free conditions. The IL could be reused at least three times without an apparent decrease in activity. NMR spectroscopy analysis revealed that strong hydrogen-bonding interactions between EG and the IL played an important role in the activation of EG and promotion of the glycolysis reaction. This study opens up avenues for exploring environmentally benign and efficient IL technology for solubilizing and recycling postconsumer polyester plastics.

Ionic Liquid-Coordinated Ferrous Acetate Complex Immobilized on Bentonite As a Novel Separable Catalyst for PET Glycolysis

Ionic liquid-coordinated ferrous acetate complex immobilized on bentonite ([Bmim—Fe][(OAc)3]/bentonite) was prepared by impregnation of [Bmim—Fe][(OAc)3] on bentonite. The prepared catalyst was characterized using FTIR, XRD and total carbon (TC). The catalyst showed a high catalytic activity in the glycolysis of polyethylene terephthalate (PET) under mild condition. Maximum activity was observed with a PET conversion of 100% and bis(2-hydroxyethyl)terephthalate (BHET) yield of 44% under the optimum conditions of catalyst (1.0 g), ethylene glycol (20 g) and PET (3.0 g) at 190 °C for 3 h. The activation energy of PET glycolysis using the prepared catalyst was calculated and found to be 51.6 kJ/mol.

Cu- and Zn-acetate-containing ionic liquids as catalysts for the glycolysis of poly(ethylene terephthalate)

The glycolysis of polyethylene terephthalate (PET) was studied using 1-butyl-3-methylimidazolium acetate-promoted copper acetate (Cu(OAc)2-[Bmim][OAc]) and 1-Butyl-3-methylimidazolium acetate-promoted zinc acetate (Zn(OAc)2-[Bmim][OAc]) as catalysts. The effects of temperature, time, ethylene glycol (EG) amount, PET amount and catalyst dosage on the glycolysis reaction were examined. Under the optimal conditions of 1.0 g of catalyst with 20 g of EG in the presence of 3.0 g of PET at 190 °C after 3 h of glycolysis, complete PET conversion was achieved using Cu(OAc)2-[Bmim][OAc] and Zn(OAc)2-[Bmim][OAc], and the yield of bis (2-hydroxyethyl) terephthalate (BHET) reached 53.95% and 45.6%, respectively. The ionic liquid could be reused up to 6 times with no apparent decrease in the PET conversion or BHET yield. The reaction mechanism was proposed. The reaction kinetics for Cu(OAc)2-[Bmim][OAc] and Zn(OAc)2-[Bmim][OAc] was first-order with an activation energy of 56.4 kJ mol−1 and 53.8 kJ mol−1, respectively.

Synthesis and characterization of saturated polyester and nanocomposites derived from glycolyzed PET waste with varied compositions

Saturated polyester resin, derived from the glycolysis of polyethyleneterephthalate (PET) was examined as an effective way for PET recycling. The glycolyzed PET (GPET) was reacted with the mixture of phthalic anhydride and ethylene glycol (EG) with varied compositions and their reaction kinetic were studied. During polyesterification of GPET, acid and EG, the parameters like degree of polymerization (DP n ), extent of reaction (p) acid value and hydroxyl values were measured. The thermomechanical properties and the morphologies of the saturated polyester nanocomposites were examined by using a differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), wide angle X-ray diffraction (WAXRD) and transmission electron spectroscopy (TEM). There were significant differences observed in \({T}_{\textrm{g}}\), \({T}_{\textrm{m}}\) and \({T}_{\textrm{c}}\) before and after addition of GPET and clay content. Nanocomposites with lower content of organoclay showed intercalated morphology while by increasing the amount of organoclay, the exfoliated morphology was more prevalent. Water vapour transmission (WVT) was determined for saturated polyester nanocomposite sheets according to ASTM E96-80.

Effect of Support Size on the Catalytic Activity of Metal-Oxide-Doped Silica Particles in the Glycolysis of Polyethylene Terephthalate

Zinc oxide (ZnO) and cerium oxide (CeO2) nanoparticles were deposited on the surface of preformed silica spheres with diameters ranging from 60 to 750 nm. Ultrasonic irradiation was employed to promote the deposition of the metal oxide nanoparticles on the surface of silica. Silica-supported zinc oxide or cerium oxide was used as a catalyst in the glycolysis of polyethylene terephthalate, one of the key processes in the depolymerization of polyethylene terephthalate. The effect of the support size on the catalytic activity was studied in terms of monomer yield, and the monomer concentration was analyzed via high-performance liquid chromatography (HPLC). The morphologies and surface properties of the catalysts were characterized using a scanning electron microscope, a transmission electron microscope, and a BET surface area analyzer, while the monomer was characterized via HPLC and nuclear-magnetic-resonance spectroscopy. Both the zinc oxide and cerium oxide deposited on a smaller support showed better distribution and less aggregation. The high specific surface area of the smaller support catalysts provided a large number of active sites. The highest monomer yield was obtained with a catalyst of 60-nm silica support.

Synthesis and applications of unsaturated polyester resins based on PET waste

Three types of unsaturated polyester resins were synthesized from the glycolysis of polyethylene terephthalate (PET) plastic waste, considering environment, cost and properties for their applications. These synthesized unsaturated polyester resins could be used for various construction processes and materials such as no dig pipelining (NDR-1), pultrusion (PLR-1) and polymer concrete (PCR-1). PET was taken from common soft-drink bottles, and ethylene glycol (EG), diethylene glycol (DEG) and MPdiol glycol mixtures were used for the depolymerization at molar ratios. The glycolyzed PET 1st products (oligomers) were reacted with maleic anhydride, phthalic anhydride and dicyclopentadiene (DCPD) (especially for polymer concrete) to form unsaturated polyester resins with mixed styrene. The lab scale (1–5 kg) and pilot plant scale-up tests (200 kg) were experimented to evaluate the processing characteristics, viscosity, acid number and curing behaviors. The main properties such as hardness, flexural strength, tensile strength, heat distortion temperature, elongation, and chemical resistance were determined based on the various uses of the three resins. Furthermore, the applicability and the properties of these developed resins were verified through many real application tests.

Asahi Kasei gets metallocene HDPE marketing rights from Dow

This paper briefly reviews the development history of polyethylene terephthalate (PET) and the recycling of PET. As one of the most promising way to degrade PET into oligomers and monomers that can be used for the production of high-quality PET, catalytic glycolysis is highlighted in this review. The developments on metal salt, metal oxide and ionic solvent catalysts for glycolysis of PET are systematically summarized, besides, the proposed catalytic mechanisms of ionic liquids (ILs) and deep eutectic solvents (DESs) are presented. The metallic catalysts show high catalytic performance but causing serious environmental pollution and high waste treatment costs, thereby it is proposed that metal-free catalysts, especially ILs and DESs can be the “greener” alternatives to address the PET waste problem. Additionally, the studies related to the glycolysis kinetics are discussed in this review, showing the results that PET glycolysis process consists of heterogeneous and homogeneous depolymerization, and different models should be used to investigate different depolymerization stages in order to obtain a more realistic picture.

Kinetics of glycolysis of polyethylene terephthalate with zinc catalyst

Kinetics of glycolysis of polyethylene terephthalate with zinc catalyst