Preparation of levulinic acid from hexose-containing material

Claim 1

IN A PROCESS OF PRODUCING LEVULINIC ACID IN WHICH A HEXOSE-CONTAINING MATERIAL AND A STRONG ACID CATALYST ARE REACTED IN A REACTION ZONE TO PRODUCE A REACTION MIXTURE COMPRISING A SOLID RESIDUE, WATER, ACID CATALYST AND LEVULINIC ACID, THE LEVULIC ACID BEING SUBSEQUENTLY SEPARATED FROM THE REMAINDER OF THE REACTION MIXTURE BY THE STEPS OF (A) FILTERING THE SOLID RESIDUE FROM THE REACTED MIXTURE TO OBTAIN A HYDROLYSATE LIQUOR, AND (B) REMOVING THE WATER AND ACID CATALYST FROM THE HYDROLYSATE LIQUOR, THE IMPROVEMENT WHICH COMPRISES REMOVING SUBSTANTIALLY ALL OF SAID WATER AND SAID ACID CATALYST FROM SAID HYDROLYSATE LIQUOR, THEREAFTER REMOVING LACTONES FROM THE LEVULINIC ACID PRODUCT BY DISTILLATION, SAID DISTILLATION BEING EFFECTED IN THE SUBSTANTIAL ABSENCE OF WATER IN THE DISTILLATION ZONE, AND RECYCLING SAID LACTONES TO SAID REACTION ZONE.