PURIFIED TEREPHTHALIC ACID (PTA)
Product Description
Terephthalic acid (TPA) is a precursor of polyethylene terephthalate, which is used in the production of polyester fibers, polyester films, PET bottle resins, and other polyester thermoplastic resins. The terephthalic acid contains both "purified" as well as "medium” quality, or “QTA" grades. Purity is typically measured by the concentration of impurities such as 4-carboxybenzaldehyde (4-CBA) and paratoluic acid. High purity TPA typically contains very low concentrations of 4-CBA in the 5-20ppm range. Medium on QTA grades contain 4-CBA concentrations in the 50 - 200+ ppm range.
|
Description |
White crystal or powder |
Molecular formula |
C6H4(COOH)2 |
Molecular weight |
166.14 g/mol |
Boiling point |
sublimes |
Melting point |
402 oC, sublimes |
Vapor pressure |
Pa at 20 oC < 1 |
Solubility |
Insoluble in water, alcohol and ether.
Soluble in other solvents, DMF, alkali |
Process / Technology / Feedstock
Most terephthalic acid is made by the BP (formerly, Amoco) process, where a solution of 25% paraxylene in acetic acid is catalytically oxidized in air. The liquid phase reaction is conducted at 200 degrees C and 20 atm. The conversion of paraxylene is practically complete, with a selectivity of 97%. The reaction mixture is cooled to recover terephthalic acid by crystallization, dissolved in hot water, and hydrogenated using a catalyst to remove aldehydes. Fiber-grade TPA is recovered by crystallization. The yield is 95% of theoretical.
End Use
All the terephthalic acid is used in producing polyethylene terephthalate (PET), which in turn is used to make polyester fibers, bottle resins, film, and engineering resins. TPA is being increasing used in manufacture of polyester at the expense of DMT. Although terephthalic acid is favored over DMT in the production of certain types of polyester fibers (e.g., staple), no hard evidence has proven that terephthalic acid results in better-quality fibers. DMT is typically used in producing polyester fibers and films.
Complete data on PTA demand - supply, price trends, industry structure, investmnets, PTA world wide producers is available in the YnFx Polyester Chain Report 2008 the recent edition published by YNFX
You may also view the Table of Contents || Report Highlights
The report contains 150 pages packed with up-to-date statistics and objective analysis of the trends and recent development of the polyester Industry covering the entire value chain beginning from ethylene further to intermediate – PTA & MEG, down to polyester fibre and filaments. The Report presents tabulation and graphical presentation of trends in demand and supply of polyester chain country-wise from 2003 to 2007 and projections upto 2013 for both fibre and filament. Processes description, end use and derivatives along with the latest producer-wise capacity are added feature of this report. |
