| Title of Invention | PROCESS FOR PRODUCING AROMATIC CARBOXYLIC ACID |
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| Abstract | There is disclosed a process for producing an aromatic carboxylic acid( e.g. iso-or-tere-phthalic acid ) by liquid phase oxidation of an alkyl-group-substi tuted aromatic compound { e.g. p-or-m-xylene ) in acetic acid which comprises dehydrating water-containing acetic acid by azeotropic distillation in an azeotropic dis-tilation dehydration tower to recycle the dehydrated acetic acid as the solvent, and suppressing the concentration of the a1ky1 group-substituted aromatic compound in the entrainer ( e.g. n butyl acetate) which is fed at the top portion of the above tower, to at most 10% by weight by removing the above aromatic compound. The process makes it possible to proceed with efficient dehydration of water-containing acetic acid for a long period of time by preventing the separation efficiency between acetic acid and an azeotropic component from being deteriorated by the alkyl-group-substituted aromatic compound remaining in the azeotropic component. |
| Full Text | PROCESS FOR PRODUCING AROMATIC CARBOXYI\LIC ACID agent with the lapse of time and day from the start of runninq the azeotropic dehydration pilot plant, thus result entrainer which is fed at the Lop portion of said tower, to at most 10% by weight. starting material for oxidation in the present invention. As ted acet1c acid and water, which are contained in an exhaust gas discharged from the oxidation reactor, are condensed by the solvent stuck thereto is removed with a dryer to produce the objective aromatic carboxy1ic acid. part of the oxidation rection mother liquor thus separated is recycled as such or via such a treatment as entainer is led in thedehydration lower at the top portion wtih in butyl acetale and water so as to form in butyl accetable layer 4p( upper layer) and water layer 4g ( lower layer). Then the .reboiler was healed for steaming into the lower. The resultant vapor was passed through a top line b, cooled of p-xylene and n butyl acetate, and was heated for steaming 1 concentration of p-xylene in n-butyl acetate collected from the delivery port of the pump 5. analysis was made of the concentrations of aceti c acid collected from the J ine e. The resul ts are qgiven in Table 3. concentration of m -xylene i n n butyl acetate collected from the delivery port of the pump S. I concentrabion of m xylene in n butyl ace acetate collected from the delivery part of the pump 5. continuous operation days, in other words, the seperation erficiency of the azeotropic dehydration deteriorates as the acid in effluent water increases with an increase in the amount of the alkyl - qroup-substituted aromatic compound which is consecutively added to n-butyl acetate, and consequently the separation efficiency of the azeotropic dehydration is deteriorated (refer to Reference Examp1es (1 to 4) I . A process for producing an aromatic carboxylic acid which comprises subjecting an alkyl-group-substituted aromatic compound to liquid-phase oxidation with molecular oxygen in acetic acid as a solvent in the presence o( a catalyst; producing water - containing acetic acid by coo 1 :i \\^^ condensing an exhaust gas from an oxidation reactor, or by evaporating the oxidation reaction mother liquor after separating the objective aromatic carboxylic acid from the oxidation reaction liquid; and dehydrating the resultant water-containing acetic acid by means of azeotropic distillation in an axeotropic distillation dehydration tower by using an entrainer to recycle the dehydrated acetic acid as the solvent, said process being performed so as to suppress the concentration of the alkyl group-substi tuted aromatic compound in the entrainer which is fed at the top portion of said tower, to at most 10% by weight. 2 . The process for producing an aromatic carboxylic acid according to Claim 1 , wherein the alky1-group-substituted aromatic compound as a starting material is selected from the group consisting of p~xylene and m-xylene, and the objective aromatic carboxylic acid is selected from the group consisting of terephthalic acid and isophthalic acid. 3. The process for producing an aromatic carboxylic acid according to Claim 1 , wherein the entrainer is n butyl acetate. 4 . The process for producing an aromatic carboxylie acid according to Claim 1 , wherein the water-containing acetic acid is fed in the azeotropic distillation dehydration tower at an intermediate stage thereof; an azeotropic mixture distilled away through the top portion of said azeotropic distillation dehydration tower is cooled and condensed; the resultant condensate is introduced in a decanter to separate the entrainer from water ; at least part of the entrainer which is separated in said decanter is distilled to remove the alkyl-group-substituted aromatic compound conta i ned i n said entrainer, and thereafter the refined entrainer is fed in said azeotropic distillation dehydration tower at the top portion thereof. 5 A Process for producing aromatic carboxylio acid, substantially as hereinabove described and illustrated with reference to the accompanying drawing. |
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2200-mas-1998-claims duplicate.pdf
2200-mas-1998-claims original.pdf
2200-mas-1998-correspondence others.pdf
2200-mas-1998-correspondence po.pdf
2200-mas-1998-description complete duplicate.pdf
2200-mas-1998-description complete original.pdf
| Patent Number | 208468 | ||||||||
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| Indian Patent Application Number | 2200/MAS/1998 | ||||||||
| PG Journal Number | 27/2007 | ||||||||
| Publication Date | 06-Jul-2007 | ||||||||
| Grant Date | 31-Jul-2007 | ||||||||
| Date of Filing | 01-Oct-1998 | ||||||||
| Name of Patentee | MITSUBISHI GAS CHEMICAL COMPANY INC | ||||||||
| Applicant Address | 5-2 MARUNCHI 2-CHOME ,CHIYODA-KU, TOKYO. | ||||||||
Inventors:
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| PCT International Classification Number | C0763/16 | ||||||||
| PCT International Application Number | N/A | ||||||||
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PCT Conventions:
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