Purified Terephthalic Acid (PTA) Process by The Dow Chemical

The production of purified terephthalic acid (PTA) for use across all downstream polyester products. The process offered by The Dow Chemical Co. (Dow) and Davy Process Technology (DPT) has undergone a substantial upgrade to meet the high hurdles for investment, quality and environmental protection essential for success in this industry. The result is COMPRESS PTA.

Purified Terephthalic Acid (PTA) Process by The Dow Chemical

Description: Following a PTA joint licensing agreement in 2008, DPT and Dow established a comprehensive technology development program to streamline and modernize the former Inca/Technimont PTA technology. The production of PTA occurs in two stages. First, paraxylene is reacted with oxygen in the presence of a catalyst in an acetic acid solvent to yield crude terephthalic acid (CTA). This crude product is then filtered and re-slurried prior to polishing in a hydrogenation reaction after which it is crystallized, filtered and dried prior to export as purified terephthalic acid.

There are several intermediate separation and recovery operations within the conventional flowsheet, and a great deal of effort has gone into reducing the numbers of equipment items required to minimize feedstock consumption while maximizing recovery of catalyst, solvent, byproducts and energy in the most cost-effective way. For example, COMPRESS PTA incorporates these benefits:

• Energy-efficient, low-pressure binary distillation offering simpler, safer and more stable operation than conventional systems
• CTA and PTA filtration using rotary pressure filters, proven in commercial operation on PTA since 2007, resulting in a significant reduction in equipment count, improved reliability and lower energy usage.
• Simplified handling of water streams in the purification plant, thus lowering capital and operating costs.

Although based upon the conventional chemistry used on virtually all existing terephthalic acid plants, when compared with traditional technologies, COMPRESS PTA has a much lower main plant equipment count, with significantly reduced capital expenditure, and achieves a significant reduction in the variable cost of production. This reduction will also lead to a much more reliable process with high utilization factors.

COMPRESS PTA is the latest technology available from Davy Process Technology and The Dow Chemical Co. There are some significant improvements, and we are now embarking on further improvements of a fundamental nature so that our licensees will have access to the latest developments in chemistry and engineering.

Licensor: Jointly licensed by The Dow Chemical Co. and Davy Process Technology


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