Separator, reactor, and method for producing aromatic carboxylic acids

Abstract

In a process for producing an aromatic carboxylic acid, it is a dehydrating process which can achieve compactification of a step for removing water from a mixture of acetic acid and water produced in the production process, and which can reduce the consumed energy. In a production process of an aromatic carboxylic acid having an oxidation reaction step for producing a slurry of an aromatic carboxylic acid by carrying out liquid-phase oxidation reaction of an alkyl aromatic compound with an oxygen-containing gas in a solvent containing acetic acid in the presence of an oxidation catalyst, at least a portion of a mixture containing acetic acid and water produced in the production steps is separated into a permeable gas mainly comprising water and nonpermeable substances mainly comprising acetic acid, using a separation membrane having water selectivity.

1 - 7 . (canceled)  
   
   
       8 . A method of producing an aromatic carboxylic acid comprising an oxidation reaction step in which an alkyl aromatic compound is subjected to liquid-phase oxidation reaction using an oxygen-containing gas in a solvent containing acetic acid in the presence of an oxidation catalyst to produce a slurry of said aromatic carboxylic acid; a solid-liquid separation step in which said slurry is separated into a reaction mother liquid and an aromatic carboxylic acid cake; and 
 a step of separating at least a portion of a mixture of acetic acid and water produced during said steps into a permeable gas mainly comprising water and nonpermeable substances mainly comprising acetic acid by use of a separation membrane having selectivity for water.    
   
   
       9 . The method of producing an aromatic carboxylic acid of  claim 8  wherein at least a portion of the mixture fed to said separation membrane is a gas.  
   
   
       10 . The method of producing an aromatic carboxylic acid of  claim 8  wherein said mixture of acetic acid and water further contains methyl acetate, and wherein using said separation membrane having selectivity for water, at least a portion of said mixture is separated into said permeable gas, which mainly comprises water, and said nonpermeable substances, which mainly comprises acetic acid and further containing methyl acetate as another main component.  
   
   
       11 . The method of producing an aromatic carboxylic acid of  claim 10  wherein said mixture is produced in said oxidation reaction step, wherein using said separation membrane having selectivity for water, at least a portion of said mixture is separated into said permeable gas, which mainly comprises water, and said nonpermeable substances, which mainly comprises acetic acid and methyl acetate, and wherein said nonpermeable substances are at least partially returned to said oxidation reaction step.  
   
   
       12 . The method of producing an aromatic carboxylic acid of  claim 10  wherein at least a portion of a mix of acetic acid, a methyl acetate as a byproduct, and water, said mix being produced in a production process, is supplied into a distillation column, wherein at least a portion of the acetate in said mix is recovered from a bottom of said distillation column, wherein at least a portion of said mix is produced from a top of said distillation column as said mixture containing acetic acid, methyl acetate and water, wherein using said separation membrane having selectivity for water, at least a portion of said mixture is separated into said permeable gas, which mainly comprises water, and said nonpermeable substances, which mainly comprises acetic acid and methyl acetate.  
   
   
       13 . The method of producing an aromatic carboxylic acid of  claim 12  wherein a portion of said mixture produced from the top of said distillation column is returned to said distillation column, and the remainder of said mixture is separated, using said separation membrane having selectivity for water, into said permeable gas, which mainly comprises water, and said nonpermeable substances, which mainly comprises acetic acid and methyl acetate.  
   
   
       14 . The method of producing an aromatic carboxylic acid of  claim 12  wherein said nonpermeable substances are returned to said oxidation reaction step.  
   
   
       15 . The method of producing an aromatic carboxylic acid of  claim 8  wherein using a separation membrane having selectivity for water, said permeable gas, which mainly comprises water, is further separated into a permeable gas mainly comprising water and nonpermeable substances mainly comprising acetic acid.  
   
   
       16 . The method of producing an aromatic carboxylic acid of any of  claim 15 , wherein one of said separation membranes that is provided upstream from the other is one that is higher in the permeating speed, and the other is one that is higher in the separation ability.  
   
   
       17 . The method of producing an aromatic carboxylic acid of  claim 8  wherein said separation membrane or said separation membranes are made of an inorganic material.  
   
   
       18 . The method of producing an aromatic carboxylic acid of  claim 17  wherein said separation membrane or said separation membranes comprise an inorganic porous member carrying in pores thereof a silica gel obtained by hydrolyzing an alkoxysilane containing ethoxy groups or methoxy groups.  
   
   
       19 . The method of producing an aromatic carboxylic acid of  claim 8  wherein said alkyl aromatic compound is paraxylene, and said aromatic carboxylic acid is terephthalic acid.