The pollution control of polyethylene terephthalate (PET) and the resource utilization of waste biomass are important issues for sustainable development. This study uses discarded oyster shell biomass after consumption as a precursor to prepare highly active calcium oxide-based catalysts through high-temperature calcination, achieving synergistic governance of “treating waste with waste.” The thermal stability, microscopic morphology and crystalline structure of the oyster shell matrix were systematically characterized through TGA, SEM, and XRD, and the correlation mechanism between the catalytic activity and physical and chemical properties was clarified. Based on single-factor experimental results, the response surface methodology (RSM) was used to optimize the PET glycolysis process in a multivariate way, and a mathematical model was established by combining with the Design–Expert software to quantify the interactions of the parameters of reaction temperature (199℃), time (3.8 h), ethylene glycol dosage (16 mL), and catalyst dosage (0.39

An integrated closed-loop strategy for high-quality recycling of waste polyethylene terephthalate (PET) entails catalytic depolymerization to bis(2-hydroxyethyl) terephthalate (BHET), followed by repolymerization into virgin PET. This approach offers significant advantages: it reduces carbon emissions, eliminates redundant separation processes, lowers energy and material consumption, enables production of high-value-added products, and maximizes the utilization of high-quality waste PET feedstock. In this study, a bio-based chelating titanium glycinate catalyst was innovatively designed and successfully synthesized using glycine as the chelating ligand. This catalyst exhibits excellent stability, good dispersibility, and moderate catalytic activity-preserving the eco-friendly characteristics of titanium-based catalysts while enabling its application in both the glycolysis of waste PET (depolymerization) and the subsequent repolymerization into PET. Response surface methodology (RSM) was employed to optimize the process conditions for the titanium glycinate-catalyzed glycolysis of waste PET, using ethylene glycol (EG) as the depolymerization agent. Experimental results revealed that the factors influencing BHET yield follow the order: reaction temperature > catalyst dosage > EG/PET molar ratio. Under the optimized conditions (reaction temperature: 194.70 degrees C, catalyst dosage: 0.048 %, EG/PET molar ratio: 14.19), a BHET yield of 91.16 % was achieved. Subsequently, virgin PET was directly repolymerized from the EG solution containing BHET, with the same titanium glycinate catalyst retained from the depolymerization step. Experiments confirmed the catalyst's high catalytic activity and robust process stability throughout both reaction stages. This study provides a green, efficient, and integrated catalytic solution for the closed-loop recycling of waste PET, addressing key challenges in sustainable polymer waste management.

Polyethylene terephthalate (PET) is a key polyester material, and the performance of catalysts in its synthesis is critical to product quality and production costs. Currently, commonly used metal catalysts have drawbacks such as poor environmental friendliness and insufficient stability. Among them, titanium-based catalysts are green, non-toxic, and exhibit high catalytic efficiency; however, traditional titanium-based catalysts are prone to hydrolysis and tend to induce side reactions. To address this challenge, this study employed titanate as the titanium source and glycine as the ligand to prepare a chelated titanium glycinate catalyst. The objective was to enhance the catalyst's hydrolysis resistance through the chelation structure, while evaluating its catalytic performance in the polycondensation of bis(hydroxyethyl) terephthalate (BHET). Response Surface Methodology (RSM) was employed to optimize reaction conditions for enhanced PET synthesis. The catalyst structure and performance were characterized using Fourier Transform Infrared Spectroscopy (FT-IR), Hydrogen Nuclear Magnetic Resonance Spectroscopy (1H NMR), Scanning Electron Microscopy (SEM), and Energy Dispersive Spectroscopy (EDS). The results demonstrated that the successfully synthesized titanium glycinate possessed excellent catalytic performance and hydrolysis resistance. Under the optimal reaction conditions (reaction time: 2.58 h, reaction temperature: 258 degrees C, catalyst dosage: 0.04 %), the molecular weight of the condensation product could reach 9803 g/mol. This study provides a novel insight into the development of highly efficient and stable catalysts for green PET synthesis, which is of great significance for expanding the application scope of chelated titanium catalysts and promoting the sustainable development of the polyester industry.

A biomass-based catalyst (SMS-750) was prepared from waste sunflower seed husk to catalyze the alcoholysis of waste PET to obtain a high value-added product (BHET).

This study investigated the microwave-assisted glycolysis of polyethylene terephthalate (PET) using ethylene glycol (EG) to produce colorless bis(2-hydroxyethyl) terephthalate (BHET). Based on the Box-Behnken design combined with response surface methodology, the optimal reaction conditions were determined as follows: mass ratio of EG to PET (w(EG): w(PET)) of 4:1, catalyst dosage of 0.52 wt% relative to PET mass, microwave power of 720 W, and depolymerization duration of 42 min. Through morphological characterization of depolymerized products under microscopic observation, the purification process of BHET was optimized to prevent structural defects during crystallization. Under these optimized conditions, a BHET yield of 91.98 % was achieved. Compared with conventional heating methods, microwave irradiation significantly reduces the high-temperature residence time of the reaction, thereby effectively suppressing side reactions. This improvement results in marked enhancement of BHET chroma and enables its potential to produce PET.

Chelated titanium adipate with stable properties was prepared via an ester-exchange reaction using low-carbon alkyl titanate, and it was characterized and analyzed using infrared spectroscopy, thermogravimetry, and scanning electron microscopy. Diisooctyl adipate (DOA) was synthesized via an ester-exchange method using the synthesized novel titanium adipate as a catalyst and isooctanol and dimethyl adipate as raw materials, where dimethyl adipate is the methyl esterification product of the by-product (mixed dicarboxylic acid) in industrial adipic acid production. The process is easy to carry out, green and environmentally friendly, and the methanol by-product can be recycled and utilized. With the objective of optimizing the DOA ester exchange rate, the effects of three factors, namely, catalyst dosage, the molar ratio of isooctanol to dimethyl adipate and the reaction temperature at catalyst addition, on the optimization objective were systematically investigated via one-way and response surface tests. Analysis of variance (ANOVA) and parameter optimization were conducted using Design-Expert software to obtain the optimal parameter combinations and verify the accuracy of the experimental results. The results showed that the optimal reaction conditions were as follows: a catalyst dosage of 2.39%, an isooctanol to dimethyl adipate molar ratio of 2.55 : 1, and a reaction temperature of 117 °C at the time of catalyst addition; this resulted in a high ester exchange rate of 94.23%. Due to the high catalytic efficiency, environmental friendliness and energy saving, and recyclable catalyst, this study provides a feasible process for the effective synthesis of DOA using industrial by-products, which is of significance.

The glycolysis of PET represents a pivotal approach to achieving high-value utilization following its disposal. However, an efficient and cost-effective catalyst is required. This study reports on the use of a titanium isophthalate (Ti-IPA) catalyst for PET depolymerization. Ti-IPA was prepared using isophthalic acid and titanate as raw materials via a one-pot method. The study investigated the effects of different titanium sources and solvent types on Ti-IPA. The optimal conditions for the glycolysis reaction were determined using response surface methodology, and the 0.86% Ti-IPA catalyst provided a BHET yield of 84.86% for a reaction lasting 3.15 h at 194 degrees C with 12.8 mL ethylene glycol. Finally, a comparative analysis of the catalytic performance of Ti-IPA revealed that it is a promising novel catalyst with significant commercial potential. The glycolysis of PET represents a pivotal approach to achieving high-value utilization following its disposal.

The recycling of post-consumer PET is a significant area of scientific research, with great importance for resource recycling and environmental protection. Here, we present our work on the glycolytic depolymerization of post-consumer PET, and we utilized kitchen waste shrimp shells as a raw material to prepare a derivative catalyst. To optimize the reaction in terms of PET conversion and BHET yield, the RSM based on the Box-Behnken design was applied for the process of the reaction. Based on the experimental results, regression models as a function of significant process parameters were obtained and evaluated by ANOVA to predict the depolymerization performance of X-700; the conversion of PET is 100% and the yield of BHET is 80.84% under the optimization conditions by the RSM. The yield of BHET still reached 76.30% after 3 cycles. The catalyst offers several advantages, including superior catalytic activity, low cost, environmental friendliness, a simple preparation method, and reusability. These advantages can provide valuable references for the preparation of biomass catalysts and their application in polymer waste. The recycling of post-consumer PET waste is a significant area of scientific research, with great importance for resource recycling and environmental protection.

Silicon catalysts have very low catalytic activity in polyester (PET). However, titanium catalysts have high catalytic activity in polyester. The simultaneous use of titanium and silicon catalysts is effective in reducing the activity of a single titanium catalytic base agent. In addition, the glycol salts of titanium and silicon (Ti-EG and Si-EG) prepared in the present invention for use in the polyester catalytic process can avoid the introduction of other groups of impurities during the polyester catalytic process, which would lead to premature capping of the polyester in the process of polycondensation and chain building and make it difficult to increase the molecular weight, and thus affect the quality of the polyester. It has been verified that the ratio of Ti:Si is 1:1 (mol), and total amount added to the catalyst is 0.15% of the raw material amount, and the polycondensation temperature was 260-280 °C for 60 min. Compared with the single Ti-EG catalyst, the b* value of the synthesized PET was significantly reduced, and the molecular weight and other indexes did not change too much. In addition, at the end of catalysis, the catalyst was uniformly dispersed in the reaction system, which could be used as a matting agent for PET.

Acetylacetone titanium oxide (TiO(acac) 2 ) was synthesized from acetylacetone and isopropyl titanate via a one-pot method.

In this study, a Ti–Si–ethylene glycol salt (Ti/Si–EG) was synthesized and used as a catalyst for the depolymerization of PET–ethylene glycol to form bis(hydroxyethyl)terephthalate (BHET), and catalysts for the resynthesis of PET by BHET.

The rapid development of industry in recent years has led to the introduction of serious pollutants into water bodies, and there is an urgent need for efficient organic degradation technologies. At present, selective peroxynitrite (PS) oxidation (SR-AOPs) is an effective way to treat pollutants in water bodies, and it is necessary to select a suitable material for the activation of peroxynitrite. Metal-organic frameworks (MOFs), with their tunable structure, large specific surface area, and tunable ligand molecules exhibit excellent reactivity and catalytic performance in the activation of persulfate. With MOF-based materials for PS activation as a novel advanced oxidation technology, this study reviews MOFs and their composites and derived materials. The current research status of activated persulfate for the treatment of organic pollutants in water, the influence of different systems on the degradation performance are discussed, and the activation and degradation mechanisms are discussed; the problems of the above materials in the degradation of organic pollutants are summarized, and research directions based on the coupled activated persulfate system of MOF materials are proposed.

Castor oil is a widely used biomass energy source. In this paper, the process conditions for the preparation of sebacic acid by cracking castor oil using the microwave method were investigated using environmentally friendly and recyclable liquid paraffin (petrolatum) as a solvent. The optimum conditions for the reaction were determined in the experiments as follows: the mass ratio of solvent: castor oil: sodium hydroxide was 4:1:2.5 and the concentration of sodium hydroxide solution was 50% (w/t). The average microwave power was 210 W, the temperature was about 280 °C, the cracking time was 25 min under nitrogen protection, and the yield of sebacic acid was measured to be 85%. The solvents can be recycled and the recovered solvent can be used again without affecting the yield of sebacic acid. The solvent recovery was more than 92%.

在介绍金属氧化物催化剂酯交换反应意义的基础上,综述了近年来用于酯交换反应的各种金属氧化物催化剂的制备方法及其应用体系,包括过渡金属氧化物催化剂、碱金属氧化物催化剂、碱土金属氧化物催化剂和其他金属氧化物催化剂,分析各类催化剂的优点及不足,总结了目前催化剂研究存在的问题,并展望了未来金属氧化物催化剂在酯交换领域的应用前景.

A titanium benzoate (Ti-BA) catalyst was prepared by hydrothermal method, which has an ordered eight-face structure, and was used for polyethylene terephthalate (PET) depolymerization. With bis(2-hydroxyethyl)terephthalate (BHET) as the target molecule and ethylene glycol (EG) as the solvent, the best reaction conditions for catalytic alcoholysis via a PET alcoholic solution were investigated via response surface experiments and found to be a EG/PET mass ratio of 3.59, temperature of 217 °C and reaction time of 3.3 h. Under these conditions, the amount of the catalyst required was only 2% of the mass of the PET, and the yield of BHET reached 90.01% and under the same conditions, the yield of BHET could still reach 80.1%. Based on the experimental results, the mechanism of alcoholysis, Ti-BA catalyst activated ethylene glycol deprotonation to achieve the progressive degradation of polymers. This experiment provides a reference for the degradation of polymer waste and other transesterification reactions.

A series of solid catalysts(HPWx/SMH-SiO2)with different HPW amounts were prepared by incipient impregnation method using submicron hollow silicon dioxide(SMH-SiO2)prepared by hard template method as support and phosphotungstic acid(HPW)as active component.The catalysts were systematically analyzed by infrared spectroscopy,ultraviolet spectrophotometry,X-ray diffraction,scanning electron microscopy,transmission electron microscopy and energy spectrum elements.The results show that HPW is successfully loaded into the hollow structure of SMH-SiO2,and HPW/SMH-SiO2 structure is complete with high thermal stability,chemical stability,catalytic activity in one-step synthesis adipic acid from hydrogen peroxide oxidation with cyclohexene.The catalyst is easy to be separated and recycled.

Herein, a new approach for glycerol monooleate (GMO) was developed. GMO was synthesized via the esterification method using self-made sodium oleate and 3-chloro-1,2-propanediol as reactants, tetrabutylammonium bromide as the catalyst, and toluene as the solvent. The effects of the reaction molar ratio, type and amount of catalyst, and reaction temperature and time on the yield were investigated. Results showed that the optimal process conditions for synthesizing GMO were as follows. The molar ratio of sodium oleate to 3-chloro-1,2-propanediol was 1:2, the reaction temperature was 115°C, the reaction time was 6 h, weight of toluene was 25 g, and the catalyst dosage was 3.5%. Under these conditions, high-purity GMO was synthesized with a yield of 89.02%.

Bifunctional β-Fe2O3@PDDA nanoclusters applied for the efficient photoelectrocatalytic oxygen evolution reaction and magnetic field enhanced photocatalytic degradation of pollutants.

工程教育专业认证成为我国各高校工程类专业建设的基础,对我国高等教育毕业生的未来发展至关重要.《化工专业综合实验》作为化学工程与工艺专业重要的实践课程,注重培养学生的实践能力和操作能力.经过多次的探索与实践,课题组成员不断优化课程体系、制定合理的课程内容和考核方式、建立完善的评价机制,对课程目标达成情况进行评价与分析,大大提高了教师的教学水平和学生的培养质量.