PROCESS FOR RECOVERING ISOBUTYLENE FROM C.SUB.4 HYDROCARBON FRACTION

A process for recovering isobutylene from a hydrocarbon C4 fraction according to the present invention involves the stags of treatment of said hydrocarbon C4 fraction with water at a temperature within the range of from 70 to 100.degree.C under a pressure of from 16 to 23 atm in the presence of a shaped ionite catalyst and the stage of dehydration of the resulting tart.butyl alcohol to isobutylene at a temperature within the range of from 80 to 110.degree.C under a pressure of up to 3 atm, in the presence of said catalyst. In accordance with the present invention, said treatment of the hydrocarbon C4 fraction with water is effected under the conditions of counter-current contact between the reactants at a speed of water supply of from 5 to 30 m/g hr and a speed of movement of the hydrocarbon C4 fraction in the catalyst bed of from 0.001 to 0.020 m/sec.