Abstract:
ISOPRENE IS PREPARED FROM A STREAM COMPOSED OF MIXED C5 ALIPHATICS, INCLUDING BOTH NORMAL AND BRANCHED, SATURATED AND UNSATURATED, COMPONENTS, BY SELECTIVELY OXIDATIVELY DEHYDROGENATING ONLY THE ISOOLEFINS WITHIN THE MIXED C5 STEAM. THE ISOPRENE PRODUCED IS RECOVERED, WHILE
THE REMAINDER OF THE STREAM IS SEPARATED INTO PENTANES AND N-AMYLENES, THE LATTER BEING SKELETALLY ISOMERIZED AND RECYCLED TO SELECTIVE DEHYDROGENATION.
Abstract:
ISOAMYLENES ARE PASSED THROUGH A DEHYDROGENATION REACTOR AND THE RESULTING MIXTURE OF ISOPRENE AND ISOAMYLENES PASSED TO EXTRACTIVE DISTILLATION FOR REMOVAL OF ACETYLENES, CYCLOPENTADIENE, PIPERYLENES, AND OTHER ISOPRENE POLYMERIZATION CATALYST POISONS. THE POISON-FREE OVERHEAD FROM THE EXTRACTIVE DISTILLATION UNIT IS PASSED TO A POLYMERIZATION REACTOR FOR PRODUCTION OF CIS-POLYISOPRENE. ISOAMYLENES TOGETHER WITH UNREACTED ISOPRENE ARE RECOVERED FROM THE POLYMERIZATION EFFLUENT AND PASSED TO A LIQUIDLIQUID EXTRACTOR FROM WHICH THE RAFFINATE CONTAINING ISOAMYLENES IS RECYCLED TO DEHYDROGENATION AND THE RICH SOLVENT CONTAINING ISOPRENE IS PASSED AS THE ONLY SOLVENT TO THE EXTRACTIVE DISTILLATION UNIT. RICH SOLVENT FROM THE LATTER IS STRIPPED TO REJECT CATALYST POISONS AND THE LEAN SOLVENT PASSED TO THE EXTRACTOR. THE EXTRACTIVE DISTILLATION AND LIQUID EXTRACTION STEPS ARE THUS MADE MORE ECONOMICAL BY USING THE SAME SOLVENT IN BOTH AND BY ABSORBING ONLY THE MINOR COMPONENTS IN THE SOLVENT.
Abstract:
A PROCESS FOR THE PRODUCTION OF POLYISPRENE FROM A RELATIVELY LOW-CONCENTRATION ISOPRENE STREAM OBTAINED FROM A FEEDSTOCK OF MIXED AMYLENES. ISOAMYLENES ARE SEPARATED FROM AN-AMYLENES BY MOLECULARE SIEVES, ISOAMYLENES IN PART DEHYDROGENATED TO ISOPRENE, CATALYST POISONS REMOVED BY EXTRACTIVE DISTILLATION, AND THE ISOPRENE CONTAINED IN THE STREAM THEN POLYMERIZED TO SYNTHETIC RUBBER. THE N-AMYLENES SEPARATED BY USE OF THE MOLECULAR SIEVES ARE SKELETALLY ISOMERIZED TO ISOAMYLENES AND RECYCLED TO THE MOLECULAR SIEVE SEPARATION.