Patent ID: 7235704

Claim:
A process for preparing isobutene, comprising: dissociating tert-butanol into isobutene and water over an acid ion-exchange resin arranged as a fixed bed in at least one reactor at a temperature of from 80 to 150° C. and at a pressure of from 5 to 25 bar to obtain a reaction mixture, separating the reaction mixture into isobutene, a by-product, water and at least one mixture of undissociated tert-butanol and water; wherein the reactor is operated pseudo-isothermally, with a temperature difference between inflowing and outflowing streams of less than 15 K; wherein the dissociation is carried out to the equilibrium of the dissociation reaction in a first reaction zone, isobutene is separated off in gaseous form in a subsequent separation zone and the dissociation is continued to the equilibrium of the dissociation reaction in a subsequent reaction zone, and, if further separation zones and reaction zones are present, these process steps are repeated at least one time.