PRODUCING ISOBUTENE BY CRACKING MTBE.

摘要

The invention relates to a method for producing isobutene by cracking MTBE, wherein the following steps are carried out: a) MTBE synthesis; reacting isobutene-containing hydrocarbon mixtures (II) with methanol (III), contained in one or more methanol-containing streams (VIII, IX), on acidic ion exchangers obtaining a stream (IV) containing MTBE and TBA, b) MTBE separation; separating a stream (V) containing MTBE and TBA from stream (IV) by means of distillation, c) MTBE cracking; cracking the stream (V) on a heterogenic catalyst in the gas phase, thus obtaining a stream (VI) which contains at least isobutene, methanol, MTBE, water, and optionally TBA, d) isobutene separation; separating the stream (VI) by means of distillation, thus obtaining a stream (VII) containing more than 50 mass % of the amounts of methanol, TBA, and water contained in stream (VI), and a stream (XVII) containing isobutene, e) water separation; separating, water from the stream (VII) to below 1 mass % by means of distillation, thus obtaining a stream (VIII), f) recirculating; complete or partial recirculation of the methanol-containing stream (VIII) into the MTBE synthesis. The invention further relates to a tube bundle device comprising the following elements: i) tube bundle, ii) tube bottom, iii) deflection plates, iv) inner shell, iv) pressure bearing outer shell, comprising at least one inlet and outlet, vi) shell chamber, comprising a fluid releasing or absorbing heat, characterized in that the inner shell is connected to the deflection plates attached over the length of the tube bundle without a gap, or with a small gap, and is connected to the tube bottom, wherein the fluid present in the shell chamber encloses the inner shell on both sides.