Dehydrogenation of isopentane to isoprene

Claim 1

THE METHOD OF PRODUCING ISOPRENE WHICH COMPRISES CONTACTING ISOPENTANE WITH A CHROMIA-ALUMINA CATALYST AT A TEMPERATURE OF 1000 TO 1100* F., SEPARATING METHANE AND LIGHT GASES FROM THE DEHYDROGENATION EFFLUENT, FRACTIONATING THE RESULTING MATERIAL CONTAINING SUBSTANTIALLY ALL OF THE 5 CARBON ATOM HYDROCARBONS CONTAINED IN SAID DEHYDROGENATION EFFLUENT TO SEPARATE A FIRST FRACTION CONSISTING ESSENTIALLY OF 3-METHYL-BUTENE-1, ISOPENTANE, 2METHYL-BUTENE-1 AND ISOPRENE TOGETHER WITH A SECOND FRACTION CONSISTING ESSENTIALLY OF ISOPRENE AND 2-METHYLBUTENE-2, FRACTIONATING SAID FIRST FRACTION TO SEPARATE 3METHYL-BUTENE-1 THEREFROM, CONTACTING THE REMAINDER OF THE MATERIAL WITH AN ABSORPTION MEDIUM IN A FIRST ABSORPTION ZONE, RECYCLING ISOPENTANE FROM SAID FIRST ABSORPTION ZONE TO THE DEHYDROGENATION STEP, STRIPPING A FOURTH FRACTION CONSISTING ESSENTIALLY OF ISOPRENE AND 2METHYL-BUTENE-1 FROM THE RICH ABSORBENT MATERIAL, COMBINING SAID SECOND AND FOURTH FRACTIONS AND CONTACTING THEM WITH AN ABSORPTION MEDIUM IN A SECOND ABSORPTION ZONE, RECOERING A FIFTH FRACTION CONSISTING ESSENTIALLY OF 2METHYL-BUTENE-1 AND 2-METHYL-BUTENE-2 FROM SAID SECOND ABSORPTION ZONE, STRIPPING AN ISOPRENE FRACTION FROM THE RICH ABSORBENT MATERIAL IN SAID SECOND ABSORPTION ZONE, SEPARATING AN ISOPRENE PRODUCT FROM HEAVY OILS IN SAID ISOPRENE FRACTION, COMBINING SAID FIFTH FRACTION WITH SAID 3-METHYL-BUTENE-1 FRACTION, CONTACTING THE LAST-MENTIONED FRACTIONS WITH A CATALYST CONSISTING ESSENTIALLY OF 51 TO 59 PERCENT BY WEIGHT POTASSIUM CARBONATE, 39 TO 47 PERCENT BY WEIGHT IRON OXIDE AND 1 TO 10 PERCENT BY WEIGHT CHROMIUM OXIDE AT A TEMPERATURE OF 1100 TO 1250* F. TOGETHER WITH STEAM, SEPARATING METHANE AND LIGHT GASES FROM THE EFFLUENT OF THE LAST-MENTIONED DEHYDROGENATION ZONE, AND PASSING THE REMAINDER OF SAID EFFLUENT CONTAINING SUBSTANTIALLY ALL OF THE 5 CARBON ATOM HYDROCARBONS CONTAINED IN THE EFFLUENT OF SAID LAST-MENTIONED DEHYDROGENATION ZONE TO THE FIRST FRACTIONATION ZONE ALONG WITH THE DEMETHANIZED EFFLUENT FROM THE FIRST DEHYDROGENATION ZONE.

Claim 2

THE METHOD OF PRODUCING ISOPRENE WHICH COMPRISES CONTACTING ISOPENTANE WITH A CHROMIA-ALUMINA CATALYST AT A TEMPERATURE OF 1000 TO 1100* F., SEPARATING METHANE AND LIGHT GASES FROM THE DEHYDROGENATION EFFLUENT, FRACTIONATING THE RESULTING MATERIAL CONTAINING SUBSTANTIALLY ALL OF THE 5 CARBON ATOM HYDROCARBONS CONTAINED IN SAID DEHYDROGENATION EFFLUENT TO SEPARATE A FIRST FRACTION CONSISTING ESSENTIALLY OF 3-METHYL-BUTENE-1, ISOPENTANE, 2METHYL-BUTENE-1 AND ISOPRENE TOGETHER WITH A SECOND FRACTION CONSISTING ESSENTIALLY OF ISOPRENE AND 2-METHYLBUTENE-2, FRACTIONATING SAID FIRST FRACTION TO SEPARATE 3METHYL-BUTENE-1 THEREFROM, CONTACTING THE REMAINDER OF THE MATERIAL WITH AN ABSORPTION MEDIUM IN A FIRST ABSORPTION ZONE, RECYCLING ISOPENTANE FROM SAID FIRST ABSORPTION ZONE TO THE DEHYDROGENATION STEP, STRIPPING A FOURTH FRACTION CONSISTING ESSENTIALLY OF ISOPRENE AND 2METHYL-BUTENE-1 FROM THE RICH ABSORBENT MATERIAL, COMBINING SAID SECOND AND FOURTH FRACTIONS AND CONTACTING THEM WITH AN ABSORPTION MEDIUM IN A SECOND ABSORPTION ZONE, RECOERING A FIFTH FRACTION CONSISTING ESSENTIALLY OF 2METHYL-BUTENE-1 AND 2-METHYL-BUTENE-2 FROM SAID SECOND ABSORPTION ZONE, STRIPPING AN ISOPRENE FRACTION FROM THE RICH ABSORBENT MATERIAL IN SAID SECOND ABSORPTION ZONE, SEPARATING AN ISOPRENE PRODUCT FROM HEAVY OILS IN SAID ISOPRENE FRACTION, COMBINING SAID FIFTH FRACTION WITH SAID 3-METHYL-BUTENE-1 FRACTION, CONTACTING THE LAST-MENTIONED FRACTIONS WITH A CATALYST CONSISTING ESSENTIALLY OF 51 TO 59 PERCENT BY WEIGHT POTASSIUM CARBONATE, 39 TO 47 PERCENT BY WEIGHT IRON OXIDE AND 1 TO 10 PERCENT BY WEIGHT CHROMIUM OXIDE AT A TEMPERATURE OF 1100 TO 1250* F. TOGETHER WITH STEAM, SEPARATING METHANE AND LIGHT GASES FROM THE EFFLUENT OF THE LAST-MENTIONED DEHYDROGENATION ZONE, AND PASSING THE REMAINDER OF SAID EFFLUENT CONTAINING SUBSTANTIALLY ALL OF THE 5 CARBON ATOM HYDROCARBONS CONTAINED IN THE EFFLUENT OF SAID LAST-MENTIONED DEHYDROGENATION ZONE TO THE FIRST FRACTIONATION ZONE ALONG WITH THE DEMETHANIZED EFFLUENT FROM THE FIRST DEHYDROGENATION ZONE.