Process for preparing 2,6-dialkylnaphthalene

Abstract

A process for producing 2,6-dialkylnaphthalene from a hydrocarbon feedstock that contains at least one component selected from the group consisting of dialkylnaphthalene isomers, monoalkylnaphthalene isomers, polyalkylnaphthalenes, and naphthalene, is provided that includes the following steps:I. separating the hydrocarbon feedstock and / or a dealkylation product fed from step III into a naphthalene fraction, a monoalkylnaphthalene fraction, a dialkylnaphthalene fraction and a remaining products fraction;II. separating and purifying 2,6-dialkylnaphthalene from the dialkylnaphthalene fraction of step I;III. dealkylating the hydrocarbon feedstock and / or the remaining products fraction of step I and feeding the dealkylation product to step I; andIV. alkylating the naphthalene and monoalkylnaphthalene fractions of step I;wherein the hydrocarbon feedstock is fed to step I or step III.

Description

[0001]This application is a continuation in part of application Ser. No. 08 / 948,299 filed on Oct. 10, 1997<?insert-start id="INS-S-00001" date="20060801" ?>, now U.S. Pat. No. 6,018,086<?insert-end id="INS-S-00001" ?>.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a process for producing 2,6-dialkylnaphthalene (DAN) and, in particular, 2,6-dimethylnaphthylene (2,6-DMN) from a mixture which contains alkylnaphthalene or naphthalene.[0004]2. Discussion of the Background[0005]In the manufacture of high performance polyester resins such as polyethylene naphthalate polymer (PEN) or polybutyrene naphthalate polymer (PBN), 2,6-DMN is used as a precursor of 2,6-naphthalene dicarboxylic acid. This is because 2,6-DMN is easily oxidized to 2,6-naphthalene dicarboxylic acid, when compared to other precursors such as 2,6-diisopropylnaphthalene or 2-methyl-6-isobutyrylnaphthalenes. There are many applications for PEN, e.g., films and b...

AI Technical Summary

Problems solved by technology

Typical PBN applications include electronics, insulators and car parts, PEN and PBN have heretofore been too expensive, however, to effectively expand their markets due to the limited commercially viable processes for producing 2,6-DMN.

However, the above methods provide only unit operation (i.e. batch) for alkylation of 2-MMN, which is an expensive feedstock and is not commercially available in a large amounts.

As multiple steps complicate a process plant and increase the cost, it is not clear that the conventional processes could provide a process suitable for an economical preparation of purified 2,6-DMN.

In addition, it is very difficult to separate 2,6-DMN from other isomers by conventional separation methods such as distillation and cooling crystallization because;1) There are very small differences in the boiling points of DMN isomers, and, in particular, between 2,6-DMN and 2,7-DMN wherein the difference in boiling points is only 0.3 C, and it is nearly impossible to separate 2,6-DMN by distillation.2) The cooling of DMN isomer mixture solution of 2,6-DMN purification forms a precipitate of very fine 2,6-DMN crystals in suspension, and thus separation of the 2,6-DMN is extremely difficult.

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