Recovery of naphthenic acids

Claim 1

A CONTINUOUS PROCESS FOR RECOVERING NAPHTHENIC ACIDS FROM A NAPHTHENIC ACID-CONTAINING PETROLEUM DIESEL OIL DISTILLATE FRACTION HAVING AN END POINT OF ABOUT 625* F. WHICH COMPRISES THE STEPS OF EXTRACTING THE DIESEL OIL FRACTION WITH AN AQUEOUS SOLUTION OF A SODIUM SALT SELECTED FROM THE GROUP CONSISTING OF SOLIUM CARBONATE, SODIUM BICARBONATE, AND THEIR MIXTURES; SEPARATING THE RESULTING MIXTURE INTO AN ORGANIC PHASE AND AN AQUEOUS SODIUM NAPHTHENATE-CONTAINING PHASES; SEPARATING THE AQUEOUS PHASE FROM THE ORGANIC PHASE; CONTACTING THE SEPARATED AQUEOUS PHASES WITH CARBON DIOXIDE AT A PRESSURE IN EXCESS OF 100 P.S.I.G. IN A PRESSURE ZONE TO CONVERT THE NAPHTHENATES TO NAPHTHENIC ACIDS; SEPARATING THIS RESULTING MIXTURE AT THE AFORESAID CARBON DIOXIDE PRESSURE INTO AN AQUEOUS PHASE CONTAINING DISSOLVED SODIUM BICARBONATE AND A NAPHTHENIC ACID ORGANIC PHASE; CONVERTING THE AQUEOUS SODIUM BICARBONATE TO AQUEOUS SODIUM CARBONATE AND CARBON DIOXIDE; RECYCLING THE LIBERATED CARBON DIOXIDE TO THE AFOREMENTIONED PRESSURE ZONE; RECYLING THE AQUEOUS SODIUM CARBONATE PHASE TO THE EXTRACTION STEP; AND FREEING THE NAPHTHENIC ACIDS OF CARBON DIOXIDE TO OBTAIN THE NAPHTHENIC ACID PRODUCT.