Dimethyl Terephthalate (DMT)

GTC’s GT-DMT technology is a series of process enhancements for dimethyl terephthalate production.  The technology addresses oxidation, distillation, esterification, crystallization, and waste-water treatment resulting in lower energy consumption, increased capacity, and yield improvements.  Multiple projects aimed at the improvement of DMT production from paraxylene and methanol feedstocks have resulted in efficient processing schemes for this production route.

Our GT-DMT technology is flexible and may be implemented in increments.  Full utilization can produce a significant capacity increase in revamp situations with maximum use of existing equipment.  For grassroots projects, capital investment is significantly reduced while obtaining improved yields and maximum capacity.

Process Description

The common method for the production of DMT from paraxylene (PX) and methanol consists of four major steps: oxidation, esterification, distillation, and crystallization.  A mixture of PX and PT-ester is oxidized with air in the presence of a heavy metal catalyst.  All useful organics are recovered from the offgas and recycled to the system.  The acid mixture resulting from the oxidation is esterified with methanol (MeOH) to produce a mixture of esters.  The crude ester mixture is distilled to remove all the heavy boilers and residue produced; the lighter esters are recycled to the oxidation section.  The raw DMT is then sent to the crystallization section to remove DMT isomers, residual acids and aromatic aldehydes.  This purification produces DMT that meets world-market specifications and is preferred in some polyester applications.  By-products are recovered for sale or burned for fuel value, and usable intermediate materials are recycled.

The GTC process improvements enhance the traditional process in each of the four sections through changes in process configurations and operating conditions, alteration of separation schemes, revision of recovery arrangements, increase in the value of by-products and reduction in the total recycles in the plant.  The upgrade options may be implemented individually, combined or through a series of revamps over a period of time.

Process Advantages

  • Improved process yields
  • Higher specific throughput
  • Lower energy consumption/ton DMT produced
  • Flexible application for grassroots projects or revamps
  • Accumulated technical expertise available through engineering packages and
    follow-up services