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Optimized Liquid-Phase Oxidation

a technology of aromatic compound and liquid phase, which is applied in the preparation of carboxylic compounds, organic chemistry, chemistry apparatus and processes, etc., can solve the problems of unfavorable cstrs, unfavorable cstrs, and high capital costs of cstrs

Inactive Publication Date: 2007-12-20
EASTMAN CHEM CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0010] It is, therefore, an object of the present invention to provide a more effective and economical liquid-phase oxidation reactor and process.
[0011] Another object of the invention is to provide a more effective and economical reactor and process for the liquid-phase catalytic partial oxidation of para-xylene to terephthalic acid.
[0012] Still another object of the invention is to provide a bubble column reactor that facilitates improved liquid-phase oxidation reactions with reduced formation of impurities.
[0013] Yet another object of the invention is to provide a more effective and economical system for producing pure terephthalic acid (PTA) via liquid-phase oxidation of para-xylene to produce crude terephthalic acid (CTA) and subsequently, purifying the CTA to PTA.
[0014] A further object of the invention is to provide a bubble column reactor for oxidizing para-xylene and producing a CTA product capable of being purified without requiring heat-promoted dissolution of the CTA in water, hydrogenation of the dissolved CTA, and / or multi-step crystallization of the hydrogenated PTA.

Problems solved by technology

If the liquid phase of the multi-phase reaction medium contains an insufficient concentration of molecular oxygen (i.e., if certain portions of the reaction medium are “oxygen-starved”), undesirable side-reactions can generate impurities and / or the intended reactions can be retarded in rate.
If the liquid phase of the reaction medium contains too little of the oxidizable compound, the rate of reaction may be undesirably slow.
Further, if the liquid phase of the reaction medium contains an excess concentration of the oxidizable compound, additional undesirable side-reactions can generate impurities.
For example, CSTRs have a relatively high capital cost due to their requirement for expensive motors, fluid-sealed bearings and drive shafts, and / or complex stirring mechanisms.
Further, the rotating and / or oscillating mechanical components of conventional CSTRs require regular maintenance.
The labor and shutdown time associated with such maintenance adds to the operating cost of CSTRs.
However, even with regular maintenance, the mechanical agitation systems employed in CSTRs are prone to mechanical failure and may require replacement over relatively short periods of time.
CTA contains relatively high levels of impurities (e.g., 4-carboxybenzaldehyde, para-toluic acid, fluorenones, and other color bodies) that render it unsuitable as a feedstock for the production of PET.
Although effective, this type of conventional purification process can be very expensive.
Individual factors contributing to the high cost of conventional CTA purification methods include, for example, the heat energy required to promote dissolution of the CTA in water, the catalyst required for hydrogenation, the hydrogen stream required for hydrogenation, the yield loss caused by hydrogenation of some terephthalic acid, and the multiple vessels required for multi-step crystallization.

Method used

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Examples

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example

[0283] In this Example, certain properties of the novel CTA particles (illustrated in FIGS. 32A and 32B) and the comparative CTA (shown in FIGS. 33A and 33B) were evaluated. In particular, the CTA particles were tested for particle size, BET surface area, and dissolution rate. Testing of the CTA particles was performed in accordance with the test descriptions provided above in the Detailed Description section of this document.

[0284] The novel CTA particles were produced by partial oxidation of commercial-purity para-xylene using recycled filtrate in a bubble column reactor operated according to many embodiments of the current invention, including solvent comprising acetic acid and water, catalyst components comprising cobalt, manganese and bromine, temperature near 160° C. at the mid-elevation of the reaction medium, preferred gradients of the gas phase composition, liquid phase composition, and temperature of the reaction medium, preferred overall STR, and preferred gradients in o...

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Abstract

Disclosed is an optimized process and apparatus for more efficiently and economically carrying out the liquid-phase oxidation of an oxidizable compound. Such liquid-phase oxidation is carried out in a bubble column reactor that provides for a highly efficient reaction at relatively low temperatures. When the oxidized compound is para-xylene and the product from the oxidation reaction is crude terephthalic acid (CTA), such CTA product can be purified and separated by more economical techniques than could be employed if the CTA were formed by a conventional high-temperature oxidation process.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a divisional of application Ser. No. 11 / 154,219, entitled “Optimized Liquid-Phase Oxidation,” filed on Jun. 16, 2005, which claims priority to U.S. Provisional Application Ser. No. 60 / 606,808, filed Sep. 2, 2004 and 60 / 631,346, filed Nov. 29, 2004, the disclosures of which are incorporated herein by reference in their entirety to the extent they do not contradict statements herein.FIELD OF THE INVENTION [0002] This invention relates generally to a process for the liquid-phase, catalytic oxidation of an aromatic compound. One aspect of the invention concerns the partial oxidation of a dialkyl aromatic compound (e.g., para-xylene) to produce a crude aromatic dicarboxylic acid (e.g., crude terephthalic acid), which can thereafter be subjected to purification and separation. Another aspect of the invention concerns an improved bubble column reactor that provides for a more effective and economical liquid-phase oxidation ...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C07C63/26C07C53/21C07C63/333
CPCC07C63/26C07C51/235C07C51/23
Inventor WONDERS, ALAN GEORGELIGHTFOOT, THOMAS YOUNGWOODRUFF, THOMAS EARLHITCHCOCK, CHARLES HELTONDENTON, DAVID LEEMCCURRY, CARL NORMAN
Owner EASTMAN CHEM CO
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