Process for the decomposition of methyl tertiary-butyl ether

摘要

Preparing isobutene, involves: (A) fractional distillation of methyl tert-butyl ether (MTBE)-containing stream comprising feed MTBE (I) and recycle stream (VIII) to give MTBE-containing overhead stream (II); (B) catalytic dissociation of stream (II) to give dissociation product (IV); (C) distillation of product (IV) into overhead stream (V) comprising isobutene (more than 90 mass.%) and bottom stream (VI); (D) fractional distillation of bottom stream (VI) to obtain methanol and MTBE (more than 99%) as overhead product (VIII); and (E) recirculation of product (VIII) to step (A). Preparing isobutene by dissociation of methyl tert-butyl ether (MTBE) in the gas phase, involves: (A) fractional distillation of an MTBE-containing stream comprising feed MTBE (I) and a recycle stream (VIII) to give an MTBE-containing overhead stream (II) and a bottom stream (III) having a boiling point higher than MTBE; (B) catalytic dissociation of the overhead stream (II) obtained in step (A) to give a dissociation product (IV); (C) separation by distillation of the dissociation product (IV) obtained in step (B) into an overhead stream (V) comprising isobutene (more than 90 mass.%) and a bottom stream (VI) comprising diisobutene, MTBE and more than 50% of the methanol present in the dissociation product (IV); (D) fractional distillation of the bottom stream obtained in step (C) under conditions under which the methanol is obtained as bottom product (VII) and MTBE (more than 99%) is obtained in the overhead product (VIII); and (E) recirculation of the overhead product (VIII) to step (A).