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US 5,852,201 AGranted
Process for the distillation of crude ester in the DMT/PTA process
AssigneeHuels Aktiengesellschaft
InventorsUdo Lenz, Ulrich Neutzler, Anton Schoengen, Reinhard Sigg
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Abstract
A process for preparing crude dimethyl terephthalate, comprises oxidizing a mixture comprising para-xylene and methyl para-toluate, esterifying the oxidized mixture with methanol, separating the resulting crude ester into fractions. By separating the crude ester with a distillation column containing structured packing and using a lower bottom temperature, product yield is increased, and the process is made more economical.
Claims4
A process for preparing crude dimethyl terephthalate, comprising:
- oxidizing a mixture comprising para-xylene and methyl para-toluate, thereby forming an oxidized mixture;
- esterifying the oxidized mixture with methanol, thereby forming a crude ester;
- separating the crude ester into a plurality of fractions, comprising:
- (a) a crude dimethyl terephthalate fraction;
- (b) a high-boiling residue fraction;
- and
- (c) a low-boiling recyclable fraction;
- wherein
- said separating is performed with a distillation column comprising structured packing;
- and
- said column is operated at an overhead temperature of 100.degree.-220.degree. C., at a pressure of 30-200 mbar, and at a bottom temperature of 180.degree.-260.degree. C.;
- wherein a pressure difference between the top and the bottom of said column is at most 30 mbar.
9 more elements
Dependencies are inferred from the claim text.