PROCESS FOR PREPARING BOTH ISOPRENE AND 3-METHYLBUTENE-1 Russian patent published in 1995 - IPC

FIELD: petrochemistry. SUBSTANCE: the process for producing both isoprene and 3-methylbutene-1 comprises two-stage dehydrogenation of isopentane, condensation of contact gas at the first dehydrogenation stage, recovery of an isopentane-isoamylene fraction from the resulting condensate and separation of said fraction into an isopentane fraction and an isoamylene fraction, condensation of the contact gas at the second dehydrogenation stage, stabilization of the resulting condensate by rectification to recover a fraction containing C₃-C₄-hydrocarbons from the distillate, and an isoprene-isoamylene fraction from the stillage product. Separation of the latter fraction is carried out by extractive rectification into an isoamylene fraction recycled to the second dehydrogenation stage, and an isoprene fraction, 3-methylbutene-1 is isolated from the isopentane fraction by prompt rectification. 3- methylbutene-1 the isoamylene fraction are fed to the second dehydrogenation stage 3-methylbutene-1 is isolated together with C₃-C₄-hydrocarbons at the stabilization stage of the condensate at the second dehydrogenation stage from the distillate, and 3-methylbutene-1 is isolated by prompt rectification from the resulting distillate.. EFFECT: greater efficiency of the process.