METHOD FOR PURIFYING ISOBUTENE FROM A C4 STREAM AND PROCESS SYSTEM THEREFOR

The invention relates to a method for purifying isobutene from a C4 stream (7), which comprises at least 1-butene, 2-butene, isobutane and isobutene, comprising: isomerizing 1-butene of a material stream (12), which is obtained from the C4 stream (7) and is enriched in isobutane and isobutene, by means of a catalyst in an isomerization reactor (5) to obtain 2-butene; feeding a product stream (15) of the isomerization reactor (5) into a rectification column (6); and providing a material stream (18) enriched in isobutene by separating off said material stream (18) via a side draw (17) and/or as a bottoms product (19) of the rectification column (6) or by feeding a top product (16) of the rectification column (6), which top product is enriched in isobutane and contains isobutene in addition to the isobutane, to a second rectification column (24) in order to separate the isobutane from the isobutene and to obtain the material stream (18) enriched in isobutene in the bottoms product (26) of the second rectificatio