Process for producing levulinic acid

Claim 1

A CONTINUOUS PROCESS FOR THE PREPARATION OF LEVULINIC ACID WHICH COMPRISES CONTINUOUSLY PASSING A MIXTURE OF A HEXOSE-YIELDING MATERIAL AND A WATER SOLUTION OF A SUBSTANTIALLY NONVOLATILE CATALYST THROUGH A REACTION ZONE MAINTAINED AT AN ELEVATED TEMPERATURE AND UNDER SUPERASTMOSPHERIC PRESSURE WHEREBY SAID MIXTURE RAPIDLY ATTAINS THE ELEVATED TEMPERATURE OF SAID REACTION ZONE ANDND A SUBSTANTIAL AMOUNT OF LEVULINIC ACID IS FORMED, SEPARATING A SOLID RESIDUE FROM THE REACTANTS TO PRODUCED AN AQUEOUS PROCESS LIQUOR CONTAINING SAID CATALYST AND LEVULINIC ACID IN SOLUTION, CONTACTING SAID PROCESS LIQUOR IN A CONTACT ZONE WITH A LEVULINIC ACID EXTRACTIVE SOLVENT SUBSTANTIALLY IMMISCIBLE WITH SAID AQUEOUS PROCESS LIQUOR TO FORM AN EXTRACT LIQUID COMPRISING ESSENTIALLY SAID SOLVENT AND LEVULINIC ACID AND AN AQUEOUS CATALYSTCONTAINING RAFFINATE, CONCENTRATING THE CATALYST IN SAID RAFFINATE FOR RECYCLE TO SAID REACTION ZONE, SEPARATING LEVULINIC ACID FROM SAID EXTRACT LIQUID, AND CYCLING THE RESULTANT SOLVENT TO SAID CONTACT ZONE.