Production of butadiene

Claim 1

A PROCESS FOR THE PRODUCTION OF 1,3-BUTADIENE WHICH COMPRISES CATALYTICALLY DEHYDROGENATING NORMAL BUTANE TO NORMAL BUTENES IN A FIRST STAGE DEHYDROGENATION ZONE, SUBJECTING THE C4 HYDROCARBON CONTENT OF THE EFFLUENT FROM SAID FIRST STAGE DEHYDROGENATION ZONE TO A FIRST EXTRACTIVE DISTILLATION WITH A SOLVENT SELECTIVE FOR BUTENE-2, RECOVERING AN UNDISSOLVED FRACTION CONTAINING BUTENE-1 AND NBUTANE FROM SAID FIRST EXTRACTIVE DISTILLATION, SEPARATING BUTENE-1 FROM SAID UNDISSOLVED FRACTION IN A FIRST FRACTIONAL DISTILLATION ZONE, PASSING SAID BUTENE-1 TO A SECOND STAGE DEHYDROGENATION ZONE, RECOVERING A STREAM CONTAINING N-BUTANE FROM SAID FIRST FRACTIONAL DISTILLATION ZONE, SEPARATING C5 AND HEAVIER HYDROCARBONS FROM SAID N-BUTANE STREAM OF SAID FIRST FRACTIONAL DISTILLATION ZONE, RECYCLING THE RESULTING N-BUTANE-CONTAINING STREAMS TO SAID FIRST STAGE DEHYDROGENATION ZONE, RECOVERING SOLVENT CONTAINING DISSOLVED C4 HYDROCARBONS FROM SAID FIRST EXTRACTIVE DISTILLATION? STRIPPING A STREAM CONTAINING BUTENE-1, BUTENE-2, BUTADIENE AND N-BUTANE FROM SAID SOLVENT, PASSING SAID LATTER STREAM OF BUTENE-1, BUTENE-2, BUTADIENE AND N-BUTANE INTO A SECOND FRACTIONAL DISTILLATION ZONE, CATALYTICALLY DEHYDROGENATING BUTENES SUPPLIED TO SAID SECOND STAGE DEHYDROGENATION ZONE, RECOVERING AN EFFLUENT CONTAINING C4 AND HEAVIER HYDROCARBONS FROM SAID SECOND STAGE DEHYDROGENATION ZONE, PASSING SAID EFFLUENT INTO SAID SECOND FRACTIONAL DISTILLATION ZONE, RECOVERING A STREAM CONTAINING BUTENE-2 FROM SAID SECOND FRACTIONAL DISTILLATION ZONE, SEPARATING C5 AND HEAVIER HYDROCARBONS FROM SAID BUTENE-2 STREAM OF SAID SECOND FRACTIONAL DISTILLATION ZONE, RECYCLING THE RESULTING BUTENE-2-CONTAINING STREAM TO SAID SECOND STAGE DEHYDROGENATION ZONE, RECOVERING A STREAM CONTAINING BUTADIENE, BUTENE-1, N-BUTANE AND ISOBUTYLENE FROM SAID SECOND FRACTIONAL DISTILLATION ZONE, SUBJECTING SAID BUTADIENE, BUTENE-1, N-BUTANE AND ISOBUTYLENE STREAM TO A SECOND EXTRACTIVE DISTILLATION WITH A SOLVENT SELECTIVE FOR BUTADIENE, RECOVERING AN UNDISSOLVED FRACTION CONTAINING BUTENE-1, N-BUTANE AND ISOBUTYLENE FROM SAID SECOND EXTRACTIVE DISTILLATION, PASSING SAID UNDISSOLVED FRACTION INTO SAID FIRST FRACTIONAL DISTILLATION ZONE, RECOVERING SOLVENT CONTAINING DISSOLVED BUTADIENE FROM SAID SECOND EXTRACTIVE DISTILLATION, AND SEPARATING BUTADIENE FROM SAID SOLVENT AS THE PRODUCT OF THE PROCESS.