| abstract |
The invention relates to a process for producing high purity isobutene from a hydrocarbon cut essentially comprising olefinic hydrocarbons containing 4 carbon atoms per molecule including isobutene, also butene-1 and butene-2 compounds in a ratio which substantially corresponds to the thermodynamic equilibrium. The process comprises passing the cut into a distillation zone (3) associated with a hydroisomerization reaction zone, the bottom product of the distillation zone comprising butene-2 compoundw being passed into a second distillation zone (4), preferably an extractive distillation zone, to obtain a first effluent comprising butene-2 compounds as its major portion and a second effluent comprising normal-butane as its major portion, the major portion of the first effluent being passed into a skeletal isomerization zone (2) where the linear butenes are at least partially isomerized to isobutene, at least part of the principal effluent from the skeletal isomerization zone being recycled upstream of the reactive distillation zone (1). |