Optimized Liquid-Phase Oxidation

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.

1 . A crude terephthalic acid (CTA) composition comprising a plurality of solid CTA particles withdrawn from an oxidation reactor within which said CTA particles were at least partly formed, wherein a representative sample of said CTA particles has one or more of the following characteristics: 
 (a) contains less than about 6 ppmw of 4,4-dicarboxystilbene (4,4-DCS),    (b) contains less than about 400 ppmw of isophthalic acid (IPA),    (c) contains less than about 25 ppmw of 2,6-dicarboxyfluorenone (2,6-DCF),    (d) has a percent transmittance at 340 nanometers (% T 340 ) greater than about 60.    
     
     
         2 . The CTA composition of  claim 1  wherein said representative sample of said CTA particles contains less than about 6 ppmw of 4,4-DCS.  
     
     
         3 . The CTA composition of  claim 1  wherein said representative sample of said CTA particles contains less than about 400 ppmw of IPA.  
     
     
         4 . The CTA composition of  claim 1  wherein said representative sample of said CTA particles contains less than about 25 ppmw of 2,6-DCF.  
     
     
         5 . The CTA composition of  claim 1  wherein said representative sample of said CTA particles has a % T 340  greater than about 60.  
     
     
         6 . The CTA composition of  claim 1  wherein said representative sample of said CTA particles contains less than about 6 ppmw of 4,4-DCS and less than about 400 ppmw of IPA.  
     
     
         7 . The CTA composition of  claim 6  wherein said representative sample of said CTA particles contains less than about 25 ppmw of 2,6-DCF.  
     
     
         8 . The CTA composition of  claim 7  wherein said representative sample of said CTA particles has a % T 340  greater than about 60.  
     
     
         9 . The CTA composition of  claim 1  wherein said representative sample of said CTA particles contains less than about 6 ppmw of 4,4-DCS and less than about 25 ppmw of 2,6-DCF.  
     
     
         10 . The CTA composition of  claim 1  wherein said representative sample of said CTA particles contains less than about 6 ppmw of 4,4-DCS and has a % T 340  greater than about 60.  
     
     
         11 . The CTA composition of  claim 1  wherein said representative sample of said CTA particles contains less than about 400 ppmw of IPA and less than about 25 ppmw of 2,6-DCF.  
     
     
         12 . The CTA composition of  claim 1  wherein said representative sample of said CTA particles contains less than about 400 ppmw of IPA and has a % T 340  greater than about 60.  
     
     
         13 . The CTA composition of  claim 1  wherein said representative sample of said CTA particles contains less than about 25 ppmw of 2,6-DCF and has a % T 340  greater than about 60.  
     
     
         14 . The CTA composition of  claim 1  wherein said representative sample of said CTA particles contains less than 3 ppmw of 4,4-DCS.  
     
     
         15 . The CTA composition of  claim 1  wherein said representative sample of said CTA particles contains less than 200 ppmw of IPA.  
     
     
         16 . The CTA composition of  claim 1  wherein said representative sample of said CTA particles contains less than about 5 ppmw of 2,7-dicarboxyfluorenone (2,7-DCF).  
     
     
         17 . The CTA composition of  claim 1  wherein said representative sample of said CTA particles dissolves in one minute to a concentration of at least about 500 ppm in THF when subjected to the timed dissolution test defined herein.  
     
     
         18 . The CTA composition of  claim 1  wherein said representative sample of said CTA particles has a time constant “C” greater than about 0.5 reciprocal minutes as determine by the timed dissolution model defined herein.  
     
     
         19 . The CTA composition of  claim 1  wherein said representative sample of said CTA particles dissolves in two minutes to a concentration of at least 700 ppm in THF when subjected to the timed dissolution test defined herein, wherein said representative sample of said CTA particles has a time constant “C” greater than 0.6 reciprocal minutes as determine by the timed dissolution model defined herein.  
     
     
         20 . The CTA composition of  claim 1  wherein said representative sample of said CTA particles has an average BET surface area greater than about 0.6 meters squared per gram.  
     
     
         21 . The CTA composition of  claim 1  wherein said representative sample of said CTA particles has a mean particle size in the range of from about 20 to about 150 microns.  
     
     
         22 . The CTA composition of  claim 21  wherein said representative sample of said CTA particles has a D(v,0.9) particle size in the range of from about 30 to about 150 microns.  
     
     
         23 . The CTA composition of  claim 21  wherein a substantial portion of said CTA particles are formed of a plurality of agglomerated sub-particles having an average particle size in the range of from about 0.5 to about 30 microns.