BigPatents India

The present invention relates to a process for preparing C5-/C6-0Iefins from an olefinic starting stream comprising C4-hydrocarbons, said process comprising a )carrying out a methathesis reaction in the presence of a methathesis catalyst selected from the class consisting of transition metal compounds of metals of groups VIb, VlIb and VIII of the Periodic Table of the Elements applied to inorganic supports to convert the I-butene, 2-butene and isobutene present in the starting stream into a mixture of C2-C6- olefins and butanes, wherein, in case of a liquid phase process, the methathesis is carried out at from 0 to 150°C and a pressure of from 2 to 200 bar, or in case of a gas phase process the temperature is from 20 to 300°C and the pressure is from I to 20 bar; b) fractionating the resulting product stream by distillation to give a low boiler fraction (A) comprising C2-C4- olefins and butanes or C2-C3-0lefins, which is discharged, and a high boiler fraction comprising C4-C6-0Iefins and butanes; c) subsequently fractionating the high boiler fraction from b) by distillation to give a low boiler fraction B comprising butanes and butanes, an intermediate boiler fraction C comprising pentene and methylbutene and a high boiler fraction D comprising hexene and methylpentene; d) where all or part of the fractions Band/or C are recirculated to the process step a) and the fraction D is discharged as product.