| abstract |
1. AN INTEGRATED PROCESS FOR CONVERING P-XYLENE OR M-XYLENE TO TEREPHTHALIC ACID OR ISOPHTHALIC ACID PRODUCT HAVING A PURITY OF AT LEAST 99.95 WEIGHT PERCENT WHICH COMPRISES: (A) OXIDATION OF P-XYLENE OR M-XYLENE IN AN OXIDATION ZONE WITH OXYGEN-CONTAINING GAS UNDER LIQUID PHASE CONDITIONS IN THE PRESENCE OF ACETIC ACID AS REACTION MEDIUM AND CATALYSIS AND REMOVAL OF OXIDATION EFFUENT CONTAINING A SLURRY OF ISO- OR TEREPHTHALIC ACID IN LIQUID ACETIC ACID FROM THE OXIDATION ZONE; (B) CONCENTRATING SAID FLUID OXIDATION ZONE EFFLUENT SLURRY THROUGH THE REMOVAL OF ACETIC ACID BY CENTRIFUGAL CLASSIFICATION TO A SLURRY HAVING A SOLIDS CONTENT OF 25 TO 40% BY WEIGHT; (C) CONTACTING SAID SLURRY CONCENTRATE IN A DISPLACEMENT ZONE WITH LIQUID WATER INTRODUCED INTO NEAR THE BOTTOM OF THE DISPLACEMENT ZONE AT A TEMPERATURE IN THE RANGE OF 40 TO 100*C. AND IN AN UPWARD MOVING AMOUNT EQUAL TO 0 TO 50 PERCENT OF THE ACETIC ACID MOTHER LIQUOR CONTENT OF SAID CONCENTRATION AND 100 WEIGHT PARTS OF WATER FOR EACH 10 TO 50 WEIGHT PARTS OF PHTHALIC ACID PRESENT IN SAID CONCENTRATION AND REMOVING DISPLACED ACETIC ACID MOTHER LIQUID AS AN OVERFLOW STREAM FROM THE TOP OF THE DISPLACEMENT ZONE WATER AND SLURRY OF 10 TO 50 WEIGHT PARTS OF IMPURE ISO- OR TEREPHTHALIC ACID IN 100 WEIGHT PARTS OF WATER FROM THE BOTTOM OF THE DISPLACEMENT ZONE; (D) PURIFYING SAID WITHDRAWN SLURRY CATALYTICALLY IN AQUEOUS SOLUTION; AND (E) RECOVERING CRYSTALLINE ACID PRODUCT AS A PRECIPITATE FROM SAID CATALYTICALLY TREATED SOLUTION. |