Combination process for producing piperazine and triethylenediamine

Claim 1

IN A METHOD WHICH COMPRISES THE STEPS OF BRINGING AN AMINE FEED STOCK INTO CONTACT WITH A HYDROGENATION CATALYST IN A PRIMARY REACTION ZONE IN THE PERSENCE OF HYDROGEN AND FROM ABOUT TWO TO ABOUT TEN MOLS OF AMMONIA PER MOL OF AMINE FEED STOCK UNDER CONDITIONS OF TEMPERATURE AND PRESSURE SUFFICIENT TO CYCLIZE AT LEAST A PORTION OF SAID FEED STOCK TO FORM PIPERAZINE AND NAMINOETHYLPIPERAZINE, WHEREBY A FIRST REACTION PRODUCT IS FORMED COMPRISING AN AMINE MIXTURE, THE IMPROVEMENT WHICH COMPRISES: (A) SEPARATING SAID FIRST REACTION PRODUCT IN A FIRST SEPARATION ZONE INTO AT LEAST A PIPERAZINE FRACTION AND A SUBSTANTIALLY PIPERAZINE-FREE DISTILLATE SECOND FEED STOCK FRACTION BOILING WITHIN THE RANGE OF ABOUT 180* TO ABOUT 250*C. AND COMPRISING N-AMINOETHYLPIPERAZINE, (B) SEPARATELY BRINGING SAID SECOND FEED STOCK INTO CONTACT WITH A CYCLIZATION CATALYST IN A SECOND REACTION ZONE IN THE PRESENCE OF FROM ABOUT 0.05 TO ABOUT 0.5 OF AMMONIA PER POUND OF SAID SECOND FEED STOCK UNDER CONVERSION CONDITIONS TO CONVERT THE SECOND FEED STOCK INTO A SECOND REACTION PRODUCT COMPRISING WATER; PIPERAZINE, N-METHYLPIPERAZINE, N-ETHYLPIPERAZINE AND TRIETHYLENEDIAMINE, (C) SEPARATELY SEPARATING SAID SECOND REACTION PRODUCT IN A SECOND SEPARATION ZONE INTO A WATER FRACTION COMPRISING REACTION BY-PRODUCTS, INCLUDING N-METHYLPIPERAZINE AND N-ETHYLPIPERAZINE, A TRIETHYLENEDIAMINE FRACTION AND A CRUDE PIPERAZINE FRACTION CONTAMINATED WITH N-METHYLPIPERAZINE AND N-ETHYLPIPERAZINE, (D) RECOVERING TRIETHYLENEDIAMINE FROM SAID TRIETHYLENEDIAMINE FRACTION, AND (E) DISCARDING AT LEAST A PORTION OF SAID WATER FRACTION, (F) DISSOLVING SAID CRUDE PIPERAZINE FRACTION IN AT LEAST 60 WT. PERCENT OF WATER TO FORM AN AQUEOUS SOLUTION, (G) HOLDING SAID AQUEOUS SOLUTION AT A TEMPERATURE OF NOT MORE THAN 43*C. TO FORM A SLURRY CONTAINING A CRUDE PIPERAZINE HEXAHYDRATE PRECIPITATE AND A MOTHER LIQUOR CONTAINING SUBSTANTIALLY ALL OF THE NMETHYLPIPERAZINE AND N-ETHYLPIPERAZINE IN SAID CRUDE PIPERAZINE FRACTION, (H) RESOLVING SAID SLURRY INTO A PIPERAZINE HEXAHYDRATE FRACTION AND A MOTHER LIQUOR FRACTION, (I) RECYCLING SAID CRUDE PIPERAZINE HEXAHYDRATE PRECIPITATE TO SAID FIRST SEPARATION ZONE AND (J) RECYCLING SAID MOTHER LIQUOR FRACTION TO SAID SECOND SEPARATION ZONE WHEREBY SAID N-METHYLPIPERAZINE AND SAID N-ETHYLPIPERAZINE CONTAMINANTS ARE REMOVED WITH SAID WATER FRACTION, (K) SAID AMINE FEED STOCK COMPRISING A COMPOUND HAVING THE FORMULA: