Yield Of Bis Research Articles

Insight into interface chemistry of metal oxides anchored on biowaste-derived support for highly selective glycolysis of waste polyethylene terephthalate

The unprecedented rise of polyethylene terephthalate (PET) waste demands sustainable solutions like catalytic glycolysis, a promising recycling technology that mitigates environmental harm. Herein, we synthesized a series of novel Mo-Zn@SiO2 catalysts for PET glycolysis, derived from readily available rice husk ash via the wetness impregnation method. The optimum Mo-Zn@SiO2 exhibits exceptional activity, achieving complete PET conversion and a 90.4 % yield of bis(2-hydroxyethyl) terephthalate (BHET) – one of the highest performances reported for heterogeneous catalysts. Density functional theory (DFT) calculations suggest that the formation of the ZnMoO4 phase optimizes reactant and product adsorption energies, enhancing Lewis acidity and facilitating depolymerization. Kinetic studies reveal a low apparent activation energy (139.27 kJ/mol) for BHET production at 175–190 °C. Additionally, the catalyst demonstrates excellent recyclability, maintaining activity after five cycles. This work presents a viable and efficient strategy for PET waste valorization using a low-cost, readily available, and easily synthesized catalyst.

Engineering pKa value of 3° amine for enhanced production of dialkyl carbonate via Se-catalyzed oxidative carbonylation

C1 chemistry plays a vital role in the chemical and energy industry in terms of recycling C1 molecules and high productivity. As one of the C1 chemistry reactions, oxidative carbonylation of alcohols to corresponding dialkyl carbonates (DACs) has been studied but still has problems with catalysts in terms of corrosion and low yield of DACs. To address this issue, various Se/Ph2Se2/tertiary amine catalytic systems were applied to the oxidative carbonylation of alcohols to produce DACs, and Se/Ph2Se2/DMAP showed higher catalytic activity [60.9% yield of bis(2-methoxyethyl) carbonate (BMEC) at a turnover frequency (TOF) value = 32.5 h−1] compared to other tertiary amines (TAs) systems in the oxidative carbonylation of 2-methoxyethanol (MEG). Moreover, with this catalytic system, the oxidative carbonylation of C1–C4 n-alcohols yielded over 40% of DACs with high TOF value (over 40 h−1), which are unprecedented catalytic activity in terms of both yield and TOF value, compared with previous reports. We also found a relationship between the hydrogen bond (HB) strength of alcohol···TA and the catalytic performances. Additionally, the catalytic activity with pKa of TA showed volcano-type correlation. Finally, we investigated the role of TA and proposed a plausible mechanism based on 1H NMR study and the aforementioned correlations.

A highly porous MgAl2O4 spinel-supported Mn3O4 as a reusable catalyst for glycolysis of postconsumer PET waste

A porous MgAl2O4 spinel-supported Mn3O4 catalyst, which is an efficient and robust catalyst for polyethylene terephthalate (PET) glycolysis, was synthesized from MgAl-layered double hydroxide (LDH) as a template via thermal and chemical treatment, followed by Mn oxide loading. A mesoporous structure in the MgAl2O4 spinel provided a high surface area (278 m2/g) and defects in which Mn3O4 was highly dispersed and strongly stabilized by the substitution of Al3+ and incorporation of Mn cation into the defects. The strong interaction of Mn oxide and the porous MgAl2O4 spinel support led to a dramatic increase of moderate acidic and basic properties, and to high resistance for Mn leaching during glycolysis. Using the Mn3O4/p-spMgAl800 catalyst, a yield of bis(2-hydroxyethyl) terephthalate > 95 % was achieved within 3 h at 190 °C. Despite eleven recycling times with regeneration, the catalytic activity remained without significant deactivation and was completely recovered after thermal regeneration at 500 °C.

Acceleration under solvent-drop grinding: Synthesis of bis(indolyl)methanes using small amounts of organic solvents or ionic liquids

The reactions for the synthesis of bis(indolyl)methanes were accelerated by the addition of a few drops of solvents. Solvent effect for the addition of organic solvents and ionic liquids was examined. The yields of bis(indolyl)methanes increased by the addition of THF, 1-ethyl-3-ethylimidazolium bis(trifluoromethylsulfonyl)imide ([emim]NTf2), and 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF6). Solvent-drop grinding methodology was quite useful for the reactions of “solid + liquid” as well as “solid + solid”.

Effective Synthesis of a Biodiesel Precursor from Furan Derivatives at Room Temperature with NaHSO4 as a Recyclable Catalyst

Synthesis of a biodiesel precursor from biobased materials usually needs harsh reaction conditions such as high temperature, long time, and precious catalysts. In this article, a mild pathway was provided to directly synthesize biodiesel precursor bis(furan-2-yl)methane derivatives (BFMs) with industrial salt NaHSO₄ as a recyclable heterogeneous catalyst at room temperature. Over 99% yield of bis(5-methylfuran-2-yl)methane (BMFM) was obtained after 10 min reaction with 5-methylfurfuryl alcohol and 2-methylfuran (2-MF) as the substrates. Moreover, the addition of 2-MF in this work could effectively increase the BMFM yield and restrain the side reactions; then the proposed mechanism was also put forward according to the detailed mechanistic studies. In this condensation reaction, the electron donor substitute and conjugation structure on the furan ring is essential, and the crystalline water of the catalyst also promoted the catalytic efficiency obviously. Overall, this work provides a budget and practical approach for biodiesel production from biobased materials, which exhibit the potential for industrial application.

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.

Heterogeneous CaO(SrO, BaO)/MCF as highly active and recyclable catalysts for the glycolysis of poly(ethylene terephthalate)

A new group of basic species, CaO(SrO and BaO), supported on mesocellular siliceous foam (MCF) has been prepared and used for catalyzing glycolysis of poly(ethylene terephthalate), or PET. The physicochemical properties, structural features and catalytic activities of CaO(SrO, BaO)/MCF in glycolysis of PET processes were thoroughly evaluated. The results showed that CaO/MCF catalyst containing 12 wt% of CaO exhibited higher activity, which was attributed to effective dispersion of CaO and favorable transport of reactants on the 3D open porous structure of MCF. Under optimal conditions, 100% PET conversion and over 80% yield of bis(2-hydroxyethyl) terephthalate with high purity were obtained. For comparison, the activity of 12%CaO/MCF was also superior than 12%CaO/SBA-15 for the glycolysis of PET. Moreover, the 12%CaO/MCF catalyst exhibited excellent stability, and could be reused for five cycles without significant decrease in activity. Combined with the kinetic studies in the presence of 12%CaO/MCF, a possible catalytic mechanism was proposed.

High-efficiency glycolysis of poly(ethylene terephthalate) by sandwich-structure polyoxometalate catalyst with two active sites

Catalyst in the process on glycolysis of poly (ethylene terephthalate) (PET) wastes is a significant critical factor, which determine the efficiency and the cost of PET degradation. In this study, a kind of transition-metal-substituted polyoxometalates (POMs) Na12 [WZnM2(H2O)2(ZnW9O34)2] (M = Zn2+, Mn2+, Co2+, Cu2+, Ni2+) which have a sandwich-structure and more than two transition metal active sites show excellent catalytic performance in the glycolysis of PET under mild conditions. We investigated the effects of temperature, reaction time and catalyst amount on PET degradation and obtained the glycolysis optimal conditions. The PET could be fast and completely degraded at 190 °C for 40 min with low catalyst/PET molar ratio (0.018%) and high PET/Ethylene Glycol (EG) weight ratio (1:4), and the yield of bis(hydroxyethyl) terephthalate (BHET) is higher than 84.5%. After four-times recycling, the conversion of PET and the yield of BHET can still reach 100% and 84.5%. The exact structure of POMs Na12 [WZnM2(H2O)2(ZnW9O34)2] is confirmed by Single Crystal X-ray Diffraction (SC-XRD). Compared with traditional heteropolyacid catalysts, this catalyst possessed of at least two transition metal active sites, which lead to its an excellent catalytic capacity. The possible coordination activates mechanism for PET glycolysis is also proposed.

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.

The synthesis and characterization of Bis- (biguanide-p-phenyl) methane

To decrease the curing temperature of epoxy resin with dicyandiamide, a new kind of modified dicyandiamide curing agent was prepared with daimio diphenyl methane and dicyandiamide as raw materials, distilled water as solvent and hydrochloric acid as a catalyst. The optimum preparation technology of bis-(biguanide-p-phenyl) methane was studied by orthogonal experiments of three factors and three levels. The results show that the yield of bis-(biguanide-p-phenyl) methane reaches to 85.12% at reaction time of 4h, reaction temperature of 120 °C, mole ratio of 1:2.15. The structures of the compounds were analysed and confirmed by the Infrared spectroscopy and Hydrogen nuclear magnetic spectroscopy. The product is pure without by-products by this way and the modified dicyandiamide had higher reactivity than unmodified dicyandiamide.

The Glycolysis of Poly(ethylene terephthalate) Promoted by Metal Organic Framework (MOF) Catalysts

Three metal organic framework catalysts (ZIF-8, ZIF-67, MOF-5) were prepared and used in the glycolysis of poly(ethylene terephthalate) (PET). All catalysts showed excellent catalytic activities, especially ZIF-8. The raw material ratio in ZIF-8 catalysts was optimized. The effects of reaction conditions on the conversion of PET and yield of bis(hydroxyethyl) terephthalate (BHET) were examined. In the presence of ZIF-8, the PET pellets can be fully degraded within 1.5 h at 197 oC, and the main product and by-products were proved to be BHET monomer and its dimers, respectively.

(Mg–Zn)–Al layered double hydroxide as a regenerable catalyst for the catalytic glycolysis of polyethylene terephthalate

(Mg–Zn)–Al layered double hydroxide (LDH) was prepared by the coprecipitation method at low super saturation conditions. The prepared (Mg–Zn)–Al LDH was analyzed using XRD, FTIR, N2 adsorption–desorption, TGA and DSC, confirming the formation of pure LDH phase. The extent of polyethylene terephthalate (PET) degradation by the glycolysis process was studied using the prepared (Mg–Zn)–Al LDH. The glycolysis process was optimized in terms of catalyst concentration, temperature, time, ethylene glycol dosage. Under the optimal conditions of 1.0wt.% of catalyst with 20g of ethylene glycol (EG) in the presence of 2.0g of PET at 196°C after 3h of glycolysis, complete PET conversion was achieved and the yield of bis (2-hydroxyethyl) terephthalate (BHET) reached 75%.

Time, Temperature and Amount of Distilled Water Effects on the Purity and Yield of Bis(2-hydroxyethyl) Terephthalate Purification System

Polyethylene terephthalate (PET) bottle is one of the common plastic wastes existed in the municipal solid waste in Malaysia. One alternative to solve the abundant of PET wastes is chemical recycling of the wastes to produce a value added product. This technology not only can decrease the PET wastes in landfill sites but also can produce many useful recycled PET products. Bis(2-hydroxyethyl) terephthalate (BHET) obtained from glycolysis reaction of PET waste was purified using crystallization process. The hot distilled water was added to glycolysis product followed by cooling and filtration to extract BHET in white solid form from the product. The effect of three operating conditions namely crystallization time, crystallization temperatures and amount of distilled water used to the yield of crystallization process were investigated. The purity of crystallization products were analyzed using HPLC and DSC. The optimum conditions of 3 hours crystallization time, 2 °C crystallization temperature and 5:1 mass ratio of distilled water used to glycolize solid gave the highest yield and purity of the crystallization process. © 2015 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0)

Kinetics of poly(ethylene terephthalate) fiber glycolysis in ethylene glycol

The glycolysis of poly(ethylene terephthalate) (PET) fiber is carried out using excess ethylene glycol (EG) in the presence of Zn/Al mixed oxides. The effects of the weight ratio of EG to PET, the weight ratio of catalyst to PET, reaction temperature and reaction time on the yield of bis(hydroxyethyl terephthalate)(BHET) are investigated. The conversion of PET and yield of bis(2-hydroxyethyl terephthalate) (BHET) reach about 92.6 % and 82 % under the optimal experimental conditions. The properties of the glycolysis products have been characterized by scanning electron microscopy (SEM), infrared spectroscopy analysis (IR), differential scanning calorimeter (DSC), thermogravimetric analysis (TG) and high performance liquid chromatography (HPLC). An evolution of the glycolysis reaction is proposed. In addition, the kinetic of PET fiber is investigated. The results indicate that this glycolysis process is a first-order kinetic reaction and the activation energy is 79.3 kJ/mol, which is lower compared to the same reaction process using PET flake from the soft drink bottle.

Fast and effective glycolysis of poly(ethylene terephthalate) catalyzed by polyoxometalate

Transition-metal-substituted polyoxometalates (POMs) K6SiW11MO39(H2O) (M = Zn2+, Mn2+, Co2+, Cu2+, Ni2+) show excellent catalytic activities in the glycolysis of poly(ethylene terephthalate) (PET) under mild conditions. The effects of temperature, catalyst amount and reaction time on PET degradation are investigated. The PET could be fast and completely degraded at low catalyst/PET molar ratio (0.13%) and high PET/EG weight ratio (1:4). The yield of bis(hydroxyethyl) terephthalate (BHET) exceeds 84% with the SiW11Zn as the catalyst under atmospheric pressure at 185 °C for 30 min. The catalyst and ethylene glycol (EG) can be easily separated from the products by filtration and can be reused together. After recycling eight times, the conversion of PET and the yield of BHET can still reach 100% and 83%, respectively. The possible nucleophilic substitution mechanism for PET glycolysis using the K6SiW11ZnO39(H2O) as the catalyst is proposed. The POM catalysts are hopeful to provide the possibility for other polymer degradation.

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.

A New Technological Study on Synthesis of Bis(2-chloroethoxy)Methane

bis(2-chloroethoxy)methane was synthesized by the reaction of ethylene chlorohydrin and Oligopolyformaldehyde under sulfuric acid catalysis. optimum reaction conditions obtained were as follows: the molar ratio of Oligopolyformaldehyde and ethylene chlorohydrin of 1.2:2, catalyst dosage was 5‰mass fraction of ethylene chlorohydrin, toluene were chose as water-carrying agent, All reactant were refluxed on temperature of 110°C until no water generated. Under the optimum conditions the yield of bis(2-chloroethoxy)methane was 97.7%. The structure of bis(2-chloroethoxy)methane were conformed by ATR IR. The purity of bis(2-chloroethoxy)methane were 99% by gas chromatographic detection.

Calcined Zn/Al hydrotalcites as solid base catalysts for glycolysis of poly(ethylene terephthalate)

ABSTRACTIn this research, glycolysis of poly(ethylene terephthalate) (PET) with ethylene glycol (EG) was carried out using Zn/Al mixed oxide catalyst. These mixed oxides were prepared by calcining crystalline Zn/Al hydrotalcites at different calcination temperatures. The samples and corresponding precursors were characterized by X‐ray diffraction, BET, Fourier‐transform infrared spectra, thermogravimetry/differential thermal analysis, and Hammett titration method. The experimental results showed that Zn/Al mixed oxides obtained from hydrotalcites were found to be more active than their individual oxides for glycolysis of PET. The relationship between catalytic performance and chemical–physical features of catalysts was established. In addition, a study for optimizing the glycolysis reaction conditions, such as the weight ratio of EG to PET, catalyst amount and reaction time, was performed. The conversion of PET and yield of bis(2‐hydroxyethyl terephthalate) (BHET) reached about 92% and 79%, respectively, under the optimal experimental conditions. Moreover, it should be noted that Zn/Al mixed oxide not only provided an effective heterogeneous catalyst for glycolysis of poly(ethylene terephthalate), but also presented a novel method for decolorization of discarded colored polyester fabric. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41053.

The Glycolysis of Poly(ethylene terephthalate) Waste: Lewis Acidic Ionic Liquids as High Efficient Catalysts

Poly(ethlyene terephthalate) waste from a local market was depolymerized by ethylene glycol (EG) in the presence of Lewis acidic ionic liquids [Bmim]ZnCl3 and the qualitative analysis showed that bis(hydroxyethyl) terephthalate was the main product. Compared with ionic liquid [Bmim]Cl, the Lewis acidic ionic liquids showed highly catalytic activity in the glycolysis of poly(ethylene terephthalate) PET. Significantly, the conversion of PET and the yield of bis(hydroxyethyl) terephthalate were achieved at 100% and 83.8% with low catalyst ([Bmim]ZnCl3) loading (0.16 wt %). Investigation also showed that the catalytic activity of [Bmim]ZnCl3 was higher than that of [Bmim]MnCl3. Catalyst [Bmim]ZnCl3 can be reused up to five times and 1H-NMR results show that the recovered catalyst is similar to the fresh one. A mechanism of the glycolysis of PET catalyzed by [Bmim]ZnCl3 was proposed.