DMT

terephthalic acid

To produce fiber-grade terephthalic acid (PTA, pure terephthalic acid) from dimethyl terephthalate (DMT).

Description: (See the dimethyl terephthalate description for the steps leading to the production of this terephthalate from p-xylene and methanol.) The hydrolysis of the crude DMT is effected with water at 250 to 280℃ in the hydrolysis vessel (1) and countercurrent washing vessel (2). The aqueous reaction medium conprising methanol and byproducts is separated (3). The resultant terephthalic acid is crystallized (4).

Economics: Basis is a 150,000 - tpy combined DMT/PTA plant, West German conditions, July 1989, including compressor station, active carbon absorption for off-gas, hot oil heating system and catalyst regeneration.

   Investment, German conditions.

including DMT production, DM/tpy      1,700

   Raw materials and utilities consumption, per t product:

p-Xylene, kg
Methanol, makeup, kg
Demineralized water, kg       
Fuel, GJ

713
70
4,000
9

   The production of medium pure terephthalic acid (MTA) is possible with lower energy consumption and investment figures.

Component Names and Formula