Method of removing substance harmful to oxidation reaction in the production of benzenecarboxylic acids by oxidation

Claim 1

A METHOD OF REMOVING IRON AND TAR-LIKE BY-PRODUCTS FROM THE RESIDUE CONTAINING A HEAVY METAL OXIDATION CATALYST, SAID RESIDUE BEING DERIVED BY SEPARATING THE FORMED BENZENE CARBOXYLIC ACID AND THEN RECOVERING A SOLVENT FROM THE REACTION MIXTURE RESULTING FROM THE LIQUID PHASE OXIDATION OF AN ALKYL BENZENE WITH A MOLECULAR OXYGEN-CONTAINING GAS USING A HEAVY METAL OXIDATION CATALYST IN THE PRESENCE OF A SATURATED LOWER ALIPHATIC MONOCARBOXYLIC ACID HAVING 2 TO 4 CARBON ATOMS AS A SOLVENT, WHEREIN THE REACTION MIXTURE IS CONTAMINATED BY IRON AND TAR-LIKE OXIDATION BY-PRODUCTS WHICH ACT AS INHIBITORS FOR THE OXIDATION REACTION, SAID METHOD COMPRISING THE STEPS OF: SUBJECTING SAID RESIDUE TO EXTRACTION WITH WATER; SEPARATING THE CATALYST-CONTAINING AQUEOUS PHASE FROM THE SO-TREATED WATER-INSOLUBLE RESIDUE, ADDING AN ALKALI SALT OF A SATURATED LOWER ALIPHATIC MONOCARBOXYLIC ACID PLUS A SATURATED LOWER ALIPHATIC MONOCARBOXYLIC ACID TO THE AQUEOUS PHASE TO REGULATE THE PH OF THE AQUEOUS PHASE TO A VALUE MORE THAN 5 BUT NOT EXCEEDING 8 TO THEREBY SEPARATE THE TAR-LIKE BY-PRODUCTS AS AN OILY FLOAT AND IRON AS A PRECIPITATE OF BASIC IRON CARBOXYLATE; AND REMOVING SAID OILY FLOAT AND SAID PRECIPITATE FROM THE AQUEOUS PHASE.

Claim 2

A METHOD OF REMOVING IRON AND TAR-LIKE BY-PRODUCTS FROM THE RESIDUE CONTAINING A HEAVY METAL OXIDATION CATALYST, SAID RESIDUE BEING DERIVED BY SEPARATING THE FORMED BENZENE CARBOXYLIC ACID AND THEN RECOVERING A SOLVENT FROM THE REACTION MIXTURE RESULTING FROM THE LIQUID PHASE OXIDATION OF AN ALKYL BENZENE WITH A MOLECULAR OXYGEN-CONTAINING GAS USING A HEAVY METAL OXIDATION CATALYST IN THE PRESENCE OF A SATURATED LOWER ALIPHATIC MONOCARBOXYLIC ACID HAVING 2 TO 4 CARBON ATOMS AS A SOLVENT, WHEREIN THE REACTION MIXTURE IS CONTAMINATED BY IRON AND TAR-LIKE OXIDATION BY-PRODUCTS WHICH ACT AS INHIBITORS FOR THE OXIDATION REACTION, SAID METHOD COMPRISING THE STEPS OF: SUBJECTING SAID RESIDUE TO EXTRACTION WITH WATER; SEPARATING THE CATALYST-CONTAINING AQUEOUS PHASE FROM THE SO-TREATED WATER-INSOLUBLE RESIDUE, ADDING AN ALKALI SALT OF A SATURATED LOWER ALIPHATIC MONOCARBOXYLIC ACID PLUS A SATURATED LOWER ALIPHATIC MONOCARBOXYLIC ACID TO THE AQUEOUS PHASE TO REGULATE THE PH OF THE AQUEOUS PHASE TO A VALUE MORE THAN 5 BUT NOT EXCEEDING 8 TO THEREBY SEPARATE THE TAR-LIKE BY-PRODUCTS AS AN OILY FLOAT AND IRON AS A PRECIPITATE OF BASIC IRON CARBOXYLATE; AND REMOVING SAID OILY FLOAT AND SAID PRECIPITATE FROM THE AQUEOUS PHASE.

Claim 3

THE METHOD OF CLAIM, WHEREIN AFTER SEPARATING THE OILY FLOAT AND THE PRECIPITATE FROM THE AQUEOUS PHASE, AN ALKALI CARBONATE IS ADDED TO THE AQUEOUS PHASE TO SEPARATE AND RECOVER THE CATALYST HEAVY METAL AS A PRECIPITATE OF CARBONATE.