Polyester Industry Research Articles

Catalyst- and Solvent-Free Upcycling of Poly(Ethylene Terephthalate) Waste to Biodegradable Plastics.

Poly(ethylene terephthalate) (PET) is an important polymer with annual output second only to polyethylene. Due to its low biodegradability, a large amount of PET is recycled for sustainable development. However, current strategies for PET recycling are limited by low added value or small product scale. It is urgent to make a breakthrough on the principle of PET macromolecular reaction and efficiently prepare products with high added value and wide applications. Here, the catalyst- and solvent-free synthesis of biodegradable plastics are reported through novel carboxyl-ester transesterification between PET waste and bio-based hydrogenated dimer acid (HDA), which can directly substitute some terephthalic acid (TPA) units in PET chain by HDA unit. This macromolecular reaction can be facilely carried out on current equipment in the polyester industry without any additional catalyst and solvent, thus enabling low-cost and large-scale production. Furthermore, the product semi-bio-based copolyester shows excellent mechanical properties, regulable flexibility and good biodegradability, which is expected to substitute poly(butylene adipate-co-terephthalate) (PBAT) plastic as high value-added biodegradable materials. This work provides an environmental-friendly and economic strategy for the large-scale upcycling of PET waste.

Hybrid modeling for carbon monoxide gas-phase catalytic coupling to synthesize dimethyl oxalate process

Ethylene glycol (EG) plays a pivotal role as a primary raw material in the polyester industry, and the syngas-to-EG route has become a significant technical route in production. The carbon monoxide (CO) gas-phase catalytic coupling to synthesize dimethyl oxalate (DMO) is a crucial process in the syngas-to-EG route, whereby the composition of the reactor outlet exerts influence on the ultimate quality of the EG product and the energy consumption during the subsequent separation process. However, measuring product quality in real time or establishing accurate dynamic mechanism models is challenging. To effectively model the DMO synthesis process, this study proposes a hybrid modeling strategy that integrates process mechanisms and data-driven approaches. The CO gas-phase catalytic coupling mechanism model is developed based on intrinsic kinetics and material balance, while a Long Short-Term Memory neural network is employed to predict the macroscopic reaction rate by leveraging temporal relationships derived from archived measurements. The proposed model is trained semi-supervised to accommodate limited-label data scenarios, leveraging historical data. By integrating these predictions with the mechanism model, the hybrid modeling approach provides reliable and interpretable forecasts of mass fractions. Empirical investigations unequivocally validate the superiority of the proposed hybrid modeling approach over conventional data-driven models and other hybrid modeling techniques.

Multi-level deep domain adaptive adversarial model based on tensor-train decomposition for industrial time series forecasting

The polyester industry is a complex process industry, building a time series prediction model for new production lines or equipment with new sensors can be challenging due to a lack of historical data. The time-series data collected from sensors cross-production-line often exhibit varying distributions. Current domain adaptation (DA) approaches in data-driven time series forecasting primarily concentrate on adjusting either the features or the models, neglecting the intricacies of industrial time series data. Furthermore, constructing deep neural networks for industrial data necessitates substantial computational resources and runtime due to their large and high-dimensional nature. In order to tackle these obstacles, we propose a novel Multi-level deep domain adaptive adversarial model based on tensor-train decomposition (TT-MDAM). Our model aims to strike a dynamic balance between prediction accuracy and runtime efficiency. By integrating multiple perspectives at the feature, trend, and model levels, we leverage DA to enhance the prediction accuracy of our model in the target domain. Additionally, by analyzing the weight matrix of the neural network, we generate a low-rank model to improve operational efficiency. The application of the proposed TT-MDAM approach to both the three-phase flow facility process (TPFF) dataset and a real-world polyester esterification process dataset reveals promising results, outperforming state-of-the-art methodologies in terms of prediction performance. The results indicate that the approach provides a viable solution for building time series prediction models in industrial processes with new equipment or production lines.

Diluted oxygen realizes high productivity of 2,5-Furandicarboxylic acid under ambient temperature

The oxidation of biomass-derived 5-hydroxymethyl furfural (HMF) into 2,5-Furandicarboxylic acid (FDCA) is a favorable reaction since FDCA is an ideal alternative to petroleum-based monomer terephthalic acid in bio-based polyester industry. However, producing FDCA with high yield under mild conditions is still challenging, especially at energy-saving near-ambient temperatures. Here, we present a Pd nanoparticles catalyst supported on Vulcan XC-72 carbon (Pd/VC) that can completely convert HMF and achieve an encouraging FDCA yield (92.4%) at 30 ℃. The most important observations include yield declines at pure oxygen bubbling, and the transformation of intermediates becomes stagnant; instead, switching to the diluted oxygen is effectively driving the tandem oxidation as the over-oxidation, and thus, rapid deactivation of the Pd surface could be alleviated. The negative effect of high oxygen concentration also occurs in the dehydrogenation and oxygenation of an extended substrate. Since the decisive influence of oxygen content has often been neglected in past investigations of oxidative transformation over Pd-based catalysts, the current study may offer a critical reminder for other liquid-phase oxidation reactions.

P-Xylene Oxidation to Terephthalic Acid: New Trends

Large-scale terephthalic acid production from the oxidation of p-xylene is an especially important process in the polyester industry, as it is mainly used in polyethylene terephthalate (PET) manufacturing, a polymer that is widely used in fibers, films, and plastic products. This review presents and discusses catalytic advances and new trends in terephthalic acid production (since 2014), innovations in terephthalic acid purification processes, and simulations of reactors and reaction mechanisms.

Recent Advances in the Catalytic Hydroconversion of 5-Hydroxymethylfurfural to Valuable Diols.

Biomass, a globally available resource, is a promising alternative feedstock for fossil fuels, especially considering the current energy crisis and pollution. Biomass-derived diols, such as 2,5-bis(hydroxymethyl)furan, 2,5-bis(hydroxymethyl)-tetrahydrofuran, and 1,6-hexanediol, are a significant class of monomers in the polyester industry. Therefore, the catalytic conversion of biomass to valuable diols has received extensive research attention in the field of biomass conversion and is a crucial factor in determining the development of the polyester industry. 5-Hydroxymethylfurfural (HMF) is an important biomass-derived compound with a C6-furanic framework. The hydroconversion of HMF into diols has the advantages of being simple to operate, inexpensive, environmentally friendly, safe, and reliable. Therefore, in the field of diol synthesis, this method is regarded as a promising approach with significant industrialization potential. This review summarizes recent advances in diol formation, discusses the roles of catalysts in the hydroconversion process, highlights the reaction mechanisms associated with the specificities of each active center, and provides an outlook on the challenges and opportunities associated with the research on biomass-derived diol synthesis.

Regulating oxygen defects via atomically dispersed alumina on Pt/WOx catalyst for enhanced hydrogenolysis of glycerol to 1,3-propanediol

Tungsten-based catalyst has been widely investigated in the field of selective hydrogenolysis of secondary CO bond, such an important yet challenging strategy, in glycerol conversion, in which the product 1,3-propanediol (1,3-PDO) is of great value in polyester industry. Unfortunately, though it has been proved to be highly active, the identification of the intrinsic tungsten oxide active sites still remains unrevealed to date due to its complex microstructure. Herein, we incorporate atomically dispersed alumina as promoter in the context of the selective hydrogenation of glycerol and report a Pt/Al-WOx catalyst. This catalyst decidedly outperforms the unpromoted Pt/WOx, which elevates the 1,3-PDO yield to 2 times. Spectroscopy characterizations and chemisorption experiments have revealed that the high activity and selectivity of Pt/Al-WOx catalyst results from the more oxygen vacancies on WOx in-situ generation by the acceleration of atomically dispersed alumina in hydrogen atmosphere, which increases the selective adsorption of glycerol and the in-situ Brønsted acid sites for the selective activation of secondary CO bonds, thus largely augmenting the hydrogenolysis performance. This discovery not only provides the new strategy of defect engineering to enhance hydrogenolysis performance of secondary CO bond in biomass compounds, but reveals the unique role of the unsaturated coordination structure of WOx in chemoselective hydrogenolysis reactions.

PM2.5-bound phthalates and phthalate substitutes in a megacity of southern China: spatioseasonal variations, source apportionment, and risk assessment.

Plasticizers are ubiquitous pollutants in the environment, whereas few efforts have been made to elucidate their emission sources in the atmosphere. In this research, the spatioseasonal variations and sources of particle-bound (PM2.5) phthalates (PAEs) and their substitutes (APs) at residential sites in seven districts and at four potential point-source sites across a megacity in South China were revealed. The total concentrations of PAEs ranging from 10.7 to 528ng/m3 were substantially higher than those of APs (1.45.58.5ng/m3). Significant spatial variations in the concentrations of the pollutants were observed, which were generally higher at the sites with intensive industrial activities and the point-source sites. Most atmospheric plasticizer levels peaked in summer, probably due to the temperature-promoted volatilization. Seven sources of plasticizers were identified by the positive matrix factorization (PMF) model. The sources in less industrialized districts are mainly associated with domestic and commercial emissions and with industry in the industrialized districts. Specifically, plastics and personal care products together contributed 60% of the plasticizers in the atmosphere of this city, followed by solvents and polyester industry sources. The incremental lifetime cancer risk of inhalation exposure to bis(2-ethylhexyl) phthalate in the study city is below the acceptable level. Relatively higher risks were found for residents living around sites with intensive industrial activities and around wastewater treatment plant.

Low-Carbon Path of Geographically Matched Hybrid Energy Utilization: A Coal-To-Ethylene Glycol Process with Hydrogen from the Coupled Wind/Solar Power

The development of the polyester industry has created a growing demand for ethylene glycol (EG). Coal-to-EG (CtEG) is an important technical route for EG production in many countries, especially China. However, due to the mismatch of hydrogen-to-carbon ratio between raw coal and products, the process is endowed with high CO₂ emission intensity and wastage of carbon sources. Taking advantage of the geographical compatibility of wind/solar energy and coal-based processes in Northern China, we propose a new CtEG process with low-carbon hydrogen from the coupling of wind/solar power (WPCtEG). Based on the system modeling and simulation, the key operating parameters were studied and a dynamic hydrogen–carbon conversion framework was proposed to offset the influence of hydrogen fluctuation and reasonably configure the process system. Compared with traditional CtEG, the carbon efficiency and exergy efficiency of WPCtEG increased by 21.2 and 7.6%, respectively. The CO₂ emission intensity of this process reduced from 2.58 to 0.93 t/t-EG, whereas the production cost saves 31 $/t-EG. With the new sustainable energy and hybrid energy integration, this new process shows the development prospects of both low-carbon and high-yield efficiency.

Effective Hydrogenolysis of Glycerol to 1,3‐Propanediol over Metal‐Acid Concerted Pt/WOx/Al2O3 Catalysts

AbstractSelective cleavage of secondary C−O bond is an important yet challenging strategy in glycerol valorization, and the product 1,3‐propanediol (1,3‐PDO) is of great value in polyester industry. Herein, we report a series of Pt/WOx/Al2O3 catalysts for selective hydrogenolysis of glycerol in a fixed‐bed reactor and obtain the highest space‐time yield of 1,3‐PDO (191.7*10−3 g1,3‐PDO h−1 g−1cat.) to date. Both Pt and W have substantial effects on the 1,3‐PDO yield with the optimum Pt/W atomic ratio of 1/2∼1/4. Spectroscopy characterizations as well as chemisorption experiments reveal that at the medium domain size of WOx, hydrogen spillover can take place to the greatest extent due to the improved dispersion of Pt and the suitable reducibility of WOx. Dehydration/dehydrogenation tests of 2‐butanol suggest that strong Brønsted acid sites are created via hydrogen dissociation at the Pt−WOx interface and spillover to the neighboring oxygen atom. Such in situ formed protons are critical to the selective cleavage of secondary C−O bonds of polyols.

Life cycle assessment and the willingness to pay of waste polyester recycling

As an important approach to recover solid waste, the recycling of waste polyester has drawn a growing level of public concern. This study aims to investigate the life cycle assessment and social cost of life cycle assessment of waste polyester recycling. The results show that the polyester recycling process itself has significant environmental impact on global warming, fossil resource scarcity, human carcinogenic toxicity, water consumption and terrestrial ecotoxicity. Global warming, terrestrial ecotoxicity and land use are the most influential categories of social cost of life cycle assessment, with a contribution of 55.7%, 10.9% and 6.3% respectively. Through key process identification, sensitivity analysis and integrated evaluation study, it is found that electricity generation, direct air emissions and transportation are key processes that affect social cost of life cycle assessment and life cycle assessment. The effects of these key processes on social cost of life cycle assessment are greater than that on life cycle assessment. Consequently, the corresponding optimization measures are proposed in order to improve the sustainability performance of polyester industry.

Research on Knowledge Discovery and Stock Forecasting of Financial News Based on Domain Ontology

In the era of big data, how to obtain useful knowledge from online news and utilize it as an important basis to make investment decision has become the hotspot of industrial and academic research. At present, there have been research and practice on explicit knowledge acquisition from news, but tacit knowledge acquisition is still under exploration. Based on the general mechanism of domain knowledge, knowledge reasoning, and knowledge discovery, this paper constructs a framework for discovering tacit knowledge from news and applying the knowledge to stock forecasting. The concrete work is as follows: First, according to the characteristics of financial field and the conceptual cube, the conceptual structure of industry–company–product is constructed, and the framework of domain ontology is put forward. Second, with the construction of financial field ontology, the financial news knowledge management framework is proposed. Besides, with the application of attributes in ontology and domain rules extracted from news text, the knowledge reasoning mechanism of financial news is constructed to achieve financial news knowledge discovery. Finally, news knowledge that reflects important information about stock changes is integrated into the traditional stock price forecasting model and the newly proposed model performs well in the empirical analysis of polyester industry.

Indorama adds more bulk

Continuing to expand its global footprint in the polyester industry, Indorama finished 2018 by arranging for two new acquisitions, completing another, and starting up a new plant. In late December, the firm agreed to acquire Invista’s 282,000-metric-ton-per-year polyethylene terephthalate (PET) operation in Gersthofen, Germany. The facility produces industrial fibers and packaging resins. Just a few days later, it agreed to acquire an Alabama PET recycling facility from Custom Polymers. The facility can recycle both commodity and food-grade resin and has a combined annual capacity of 31,000 t. Then, just as the year came to an end, Indorama—along with partners Alpek and Far Eastern New Century—completed the acquisition of a partially-constructed purified-terephthalic acid (PTA) and PET complex in Corpus Christi, Texas. The partners agreed to buy the complex, formerly owned by the bankrupt Italian company M&G Chemicals, in March 2018 for $1.1 billion. The plant is designed to make up to

Potentials of duckweed (Lemna gibba) for treatment of 1,4-dioxane containing wastewater using duckweed multi-ponds system

Duckweed (Lemna gibba) was investigated for the treatment of wastewater containing 1,4-dioxane (e.g., polyester industry wastewater). Three continuous flow duckweed-pond systems (DWP), i.e., one pond, two ponds, and three ponds, were operated achieving different hydraulic retention time (HRT) of 2, 4 and 6 d, respectively. Results indicated that DWP3 is the most efficient one in 1,4-dioxane and NH4-N removals from wastewater. 1,4-dioxane and NH4-N removal efficiencies by DWP3 (56.9 ± 25% and 87.2 ± 7.1%, respectively) were slightly higher than that obtained by DWP2 (44.8 ± 19.6% and 81.9 ± 8.6%, respectively). It was found that, at DWP3, the pH value was reduced from 8.80 to 7.45, the dissolved oxygen (DO) was increased from 3.5 ± 1.9 to 7.5 ± 3 mg/L, and the concentration of total dissolved solids (TDS) was decreased from 921.5 ± 120.6 to 837.6 ± 83.6 mg/L. Eventually, duckweed (Lemna gibba) is effective to remove 1,4-dioxane from wastewater, representing an eco-friendly, effective and low operation and maintenance costs technology.

Process simulation, analysis and optimization of a coal to ethylene glycol process

With the rapid development of polyester industry, the increasing demand of ethylene glycol (EG) is in conflict with the shortage of supply in China. Large project of EG production from coal has been receiving more and more attention. However, little work has been done to model and simulate the complete coal to ethylene glycol (CtEG) process, and there is a lack of research analyzing or optimizing its system performance. In this paper, the CtEG process was modeled and simulated to calculate and analyze its mass and energy balance. The models were validated by comparison with industrial data. The element balance and thermodynamic performance of the CtEG process were analyzed to identify the technical bottleneck and provide theoretical support for the actual production. Key parameters were investigated and optimized for increasing the yield of product as well as improving the system performance of the CtEG process. Results indicate that, the process produce 37.50 t/h EG from 118.98 t/h coal. The exergy efficiency of the CtEG process is 30.68%. The coal gasification and EG synthesis units have the greatest potential for decrease in exergy destruction. After optimization, the production and the exergy efficiency of the process is increased by 3.04% and 2.64%.

OPTIMASI SINTESIS ASAM AZELAT DARI ASAM OLEAT DAN HIDROGEN PEROKSIDA MENGGUNAKAN KATALIS ASAM TUNGSTAT


 Azealic acid is an oleochemical product which is an output from oleic acid with oxidation cleavage process and commonly its aplication in polymer industry such as nylon production, plastic industry, glue industry and also as fiber in polyester industry. The purpose of this research is to obtain comparison design and analysis of variance in two method of synthesis azelaic acid namely one step and two steps oxidation. The result design reviewed by Response Surface Methodology using Minitab 17 trial version program with percent mass of the catalyst variable, molar ratio of the substrate variable and temperature variable. Based on the statistic analysis the percentage conversion (Y)in one step Y : 97,99 + 3,907X1 + 3,651X2 – 4,556X3 – 1,467X12 – 4,299X22 – 4,453X32 + 0,57X1X2 + 0,63X1X3 + 1,37X2X3 and for two steps Y : 98,505 + 6,164X2 + 2,164X3-7,83X22-5,18X32. The design has R2 = 92,80 % for one step and 89,95 % in two steps.

Facile fabrication of hydrolysis resistant phosphite antioxidants for high-performance optical PET films via in situ incorporation

Phosphite antioxidants are extensively used in polyester industry due to extraordinary antioxidative and chromaticity protection capabilities. Unfortunately, they are highly susceptible to hydrolysis leading to reduced antioxidative activity, which remains unsatisfactorily addressed so far. In this work, we have demonstrated the fabrication of hydrolysis resistant hybridized phosphite antioxidants (PSLDH) by physically melt-blending with layered double hydroxides (LDH) based on the hydrolysis mechanism. X-ray diffraction measurements indicate that basically phosphite antioxidants are physically hybridized with the LDH. Accelerated hydrolysis results show that as-fabricated hybridized phosphite antioxidants show much superior anti-hydrolysis capability to the unmodified counterpart because the basic LDH can neutralize the phosphoric acid created during hydrolysis, thus effectively prohibiting the self-catalytic effect. High performance optical poly(ethylene terephthalate) (PET) materials are then synthesized by in situ adding PSLDH in the polycondensation process. Only adding 0.05wt% of the PSLDH containing 10wt% of LDH can remarkably improve the anti-oxidative and chromaticity performances of the resultant PET. This work provides an innovative methodology for developing high-performance value-added chemical additives via facile physical hybridization.

MATHEMATICAL MODELING & DYNAMICS STUDY OF BATCH CRYSTALLIZER FOR PURIFIED TEREPHTHALIC ACID (PTA) CRYSTALLIZATION PROCESS USING GPROMS

Crystallization is a complex and critical chemical engineering process which is carried out for high purity products in process industry. Purified Terephthalic Acid (PTA) is commodity chemical, it is principal raw material mainly used in Polyester industry. During production process of Purified Terephthalic Acid (PTA), crystallization process is used to separate crystals from water. Crystalline materials generally have a high degree of purity even when obtained from a relatively impure solution. Control of crystal size distribution (CSD) is an end objective in PTA crystallization process. To fulfill CSD, needs the mathematical model based optimization for PTA unit, developed mathematical model is solved in gPROMS (general PROcess Modeling System).In present work, research achievement are batch crystallization modeling, simulation, optimization & parameter estimation. Within the proposed control strategy, a dynamic optimization is performed to obtain optimal cooling temperature profile of batch crystallizer, maximizing the total volume of seeded crystals. Simulation is implemented to track the resulting optimal temperature profile.

Dynamic modeling and control of industrial crude terephthalic acid hydropurification process

Purified terephthalic acid (PTA) is critical to the development of the polyester industry. PTA production consists of p-xylene oxidation reaction and crude terephthalic acid (CTA) hydropurification. The hydropurification process is necessary to eliminate 4-carboxybenzaldehyde (4-CBA), which is a harmful byproduct of the oxidation reaction process. Based on the dynamic model of the hydropurification process, two control systems are studied using Aspen Dynamics. The first system is the ratio control system, in which the mass flows of CTA and deionized water are controlled. The second system is the multivariable predictive control-proportional-integral-derivative cascade control strategy, in which the concentrations of 4-CBA and carbon monoxide are chosen as control variables and the reaction temperature and hydrogen flow are selected as manipulated variables. A detailed dynamic behavior is investigated through simulation. Results show that the developed control strategies exhibit good control performances, thereby providing theoretical guidance for advanced control of industry-scale PTA production.

One-Pot Conversion of Cellulose to Ethylene Glycol with Multifunctional Tungsten-Based Catalysts

With diminishing fossil resources and increasing concerns about environmental issues, searching for alternative fuels has gained interest in recent years. Cellulose, as the most abundant nonfood biomass on earth, is a promising renewable feedstock for production of fuels and chemicals. In principle, the ample hydroxyl groups in the structure of cellulose make it an ideal feedstock for the production of industrially important polyols such as ethylene glycol (EG), according to the atom economy rule. However, effectively depolymerizing cellulose under mild conditions presents a challenge, due to the intra- and intermolecular hydrogen bonding network. In addition, control of product selectivity is complicated by the thermal instabilities of cellulose-derived sugars. A one-pot catalytic process that combines hydrolysis of cellulose and hydrogenation/hydrogenolysis of cellulose-derived sugars proves to be an efficient way toward the selective production of polyols from cellulose. In this Account, we describe our efforts toward the one-pot catalytic conversion of cellulose to EG, a typical petroleum-dependent bulk chemical widely applied in the polyester industry whose annual consumption reaches about 20 million metric tons. This reaction opens a novel route for the sustainable production of bulk chemicals from biomass and will greatly decrease the dependence on petroleum resources and the associated CO₂ emission. It has attracted much attention from both industrial and academic societies since we first described the reaction in 2008. The mechanism involves a cascade reaction. First, acid catalyzes the hydrolysis of cellulose to water-soluble oligosaccharides and glucose (R1). Then, oligosaccharides and glucose undergo C-C bond cleavage to form glycolaldehyde with catalysis of tungsten species (R2). Finally, hydrogenation of glycolaldehyde by a transition metal catalyst produces the end product EG (R3). Due to the instabilities of glycolaldehyde and cellulose-derived sugars, the reaction rates should be r₁ << r₂ << r₃ in order to achieve a high yield of EG. Tuning the molar ratio of tungsten to transition metal and changing the reaction temperature successfully optimizes this reaction. No matter what tungsten compounds are used in the beginning reaction, tungsten bronze (HxWO₃) is always formed. It is then partially dissolved in hot water and acts as the active species to homogeneously catalyze C-C bond cleavage of cellulose-derived sugars. Upon cooling and exposure to air, the dissolved HxWO₃ is transformed to insoluble tungsten acid and precipitated from the solution to facilitate the separation and recovery of the catalyst. On the basis of this temperature-dependent phase-transfer behavior, we have developed a highly active, selective, and reusable catalyst composed of tungsten acid and Ru/C. Our work has unearthed new understanding of this reaction, including how different catalysts perform and the underlying mechanism. It has also guided researchers to the rational design of catalysts for other reactions involved in cellulose conversion.