p-Xylene Oxidation to Terephthalic Acid: New Trends

Lapa, Hugo M.; Martins, Luísa M. D. R. S.

doi:10.3390/molecules28041922

Cited by 20 publications

(11 citation statements)

References 69 publications

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“…p -Xylene (PX) is a vital organic chemical raw material, which can be used as a solvent for rubber and coatings and as a standard for chromatographic analysis, especially in the preparation of terephthalic acid (PTA). − With the country’s polyester and PTA industrial chains continuing to expand and PX being an upstream raw material of the industrial chain, the market demand for PX is increasing. In the one-step synthesis of PX from isobutanol, there is an azeotropic mixture of isobutanol-PX, and the actual efficiency of the entire process relies on the successful separation of the mixture.…”

Section: Introductionmentioning

confidence: 99%

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Phase Equilibrium of p-Xylene and Isobutanol in Ionic Liquid Separations: Thermodynamic and Mechanistic Analysis

Wang,

Ruan,

Xue

et al. 2024

ACS Sustainable Chem. Eng.

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With the continuous expansion of the global polyester industry chain, the market demand for p-xylene (PX) as an upstream raw material is becoming increasingly large. In response to the call for cleanliness, consumption reduction, emission reduction, and sustainable development, three kinds of imidazole ionic liquids (ILs) were used as extractants to efficiently clean and separate the isobutanol-PX azeotropic system for the first time in this work. The conductor-like screening model for realistic solvents (COSMO-RS) and σ-profile were used to select the best extraction agent, and then, target ILs were synthesized. Their extraction effects were analyzed through liquid−liquid phase equilibrium experiments, and the separation effect of bisulfate was the best. Furthermore, given the high cost of ILs, recycling extraction experiments were performed for the first time. Finally, this work combined molecular dynamics simulation with quantum chemistry calculation to reveal the extraction mechanism from the microscopic mechanism level, which provided theoretical support for the separation of the azeotropic system of alcohols and aromatics.

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Section: Introductionmentioning

confidence: 99%

“…the binary system regressed by the NRTL model; interaction energy between the PX-isobutanol-ILs systems (kJ/mol); self-diffusivity coefficient of the PXisobutanol-ILs system; thermogravimetric analysis of the three kinds of ILs; experimental and regression data of PX (1)…”

mentioning

confidence: 99%

Phase Equilibrium of p-Xylene and Isobutanol in Ionic Liquid Separations: Thermodynamic and Mechanistic Analysis

Wang,

Ruan,

Xue

et al. 2024

ACS Sustainable Chem. Eng.

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“…The first method is based on the esterification of terephthalic acid with an excess of 2-ethylhexanol, while the second one involves the transesterification of dimethyl terephthalate (DMTP) with 2-ethylhexanol, both in the presence of organometallic compounds as catalysts. Anyway, the production of terephthalic acid via the oxidation of p -xylene is followed by its esterification with methanol to isolate the acid from the postoxidation mixture . The low solubility of terephthalic acid in common solvents makes its industrial production very difficult and not environmentally benign. , …”

Section: Introductionmentioning

confidence: 99%

“…Anyway, the production of terephthalic acid via the oxidation of p-xylene is followed by its esterification with methanol to isolate the acid from the postoxidation mixture. 42 The low solubility of terephthalic acid in common solvents makes its industrial production very difficult and not environmentally benign. 43,44 In this study, we present a sustainable DES comprising ChCl and urea, incorporating dissolved ZnO.…”

Section: ■ Introductionmentioning

confidence: 99%

Synergistic Effect of Deep Eutectic Solvent and Zinc Oxide in Transesterification of Dimethyl Terephthalate for the Synthesis of Alkyl Terephthalate Esters

Latos,

Gabzdyl,

Jurczyk

et al. 2024

Ind. Eng. Chem. Res.

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A deep eutectic solvent (DES), composed of choline chloride and urea, demonstrated exceptional solubility properties, allowing the dissolution of 0.8 wt % of zinc oxide. This liquid system was used as both solvent and catalyst (DES 300 mol %; ZnO 7.8 mol %) for the transesterification of dimethyl terephthalate (DMTP) with various alcohols (1-butanol, 2-butanol, 2-ethylhexanol, 1-hexanol, and 1-octanol). For example, the use of 1-butanol caused full conversion of DMTP after 24 h at 120 °C. The synergistic effect of the DES and ZnO was demonstrated via a comparison with the catalytic efficiency of the components used separately. The advantage of the catalytic system is the lack of miscibility of the product with DES−ZnO, resulting in the formation of a biphasic system during the reaction, the shifting of the reaction equilibrium being the main driving force for this process. DES−ZnO was used in six consecutive reaction cycles without any significant drop in efficiency.

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“…With the increasing global environment and sustainability requirements, researchers have made great efforts to explore greener TPA production technologies. A lot of research and improvement work have been carried out to pursue more energy-efficient and green TPA synthesis process conditions. ,, Since water is an excellent environment-friendly solvent, high-temperature water and sub/supercritical water have been extensively studied as solvent medium for PX oxidation in recent years. − Supercritical CO 2 , which has extremely high solvency capacity, has also been used as solvent medium for PX oxidation. , These studies achieved high yields of TPA, which were comparable to those of the commercial process, but extremely high pressure and temperature make the oxidation process dangerous and hard to be industrialized. Some studies focused on biotransformation under mild reaction conditions and avoided transition metal catalysts.…”

Section: Introductionmentioning

confidence: 99%

A Green Oxidation Process of p-Xylene to Terephthalic Acid through the UV Irradiation-Enhanced Ozonation Process

Yuan,

Cao,

Sun

et al. 2024

Ind. Eng. Chem. Res.

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The industrial oxidation of para-xylene (PX) to terephthalic acid (TPA) is the footstone of the polyester industry, but this traditional oxidation process utilizes harsh reaction conditions such as high temperatures, corrosive solvents, and catalysts. In this work, a green alternative process of PX oxidation was developed to obtain a high TPA yield of 84% when using pure acetonitrile as the solvent under conditions of ozone and UV irradiation. The key reaction conditions were optimized to avoid the occurrence of overoxidation, including solvent composition, temperatures, ozone, and UV irradiation. DFT calculations reveal that the aldehyde group on the benzene ring was generated through the dehydration of geminal diol formed by the consecutive insertion of two O( 1 D) into the same methyl group, while the carboxyl group was produced through the oxidation of the aldehyde group by ozone. When using ozone to catalyze PX oxidation to p-TA, the activity of the para-methyl group was not inhibited by the carboxyl groups, which is different from traditional PX oxidation using the Co/Mn/Br catalyst. Results show that the aldehyde group is easily oxidized by ozone alone to form a carboxyl group without light, which reveals the significant role of ozone for promoting the oxidation reaction. It was found that the presence of water helps to generate hydroxyl radicals that act on the benzene ring responsible for the ring opening of PX and other intermediates. The insights in this work may provide a green alternative approach for the large-scale production of TPA free of corrosive solvents and catalysts.

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p-Xylene Oxidation to Terephthalic Acid: New Trends

Cited by 20 publications

References 69 publications

Phase Equilibrium of p-Xylene and Isobutanol in Ionic Liquid Separations: Thermodynamic and Mechanistic Analysis

Phase Equilibrium of p-Xylene and Isobutanol in Ionic Liquid Separations: Thermodynamic and Mechanistic Analysis

Synergistic Effect of Deep Eutectic Solvent and Zinc Oxide in Transesterification of Dimethyl Terephthalate for the Synthesis of Alkyl Terephthalate Esters

A Green Oxidation Process of p-Xylene to Terephthalic Acid through the UV Irradiation-Enhanced Ozonation Process

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