| 摘要 |
Process for isolating isobutene from isobutene-containing C4-hydrocarbon mixtures by reacting the mixture with a primary alcohol in the presence of an acidic condensing agent and separating the tertiary ether formed in the presence of an acid catalyst at elevated temperatures, wherein the primary alcohol used is a primary C3- or C4-alcohol and the acidic condensing agent used for ether formation is an ion exchanger in the hydrogen form, the primary C3- or C4-alcohol and the C4-hydrocarbon mixture, with or without prior mixing, first being introduced into the reaction zone (4) for the etherification, where the ion exchanger is located, then subjecting the reaction mixture obtained from the etherification zone (4) to a distillation in a first distillation zone (6), withdrawing as head product, without inclusion of a scrub with water, a C4-hydrocarbon mixture which contains the unconverted hydrocarbons and which has a primary C3- or C4-alcohol content of not more than 1000 ppm by weight and as bottom product the C3- or C4-alkyl tert-butyl ether formed which may still contain the primary C3- or C4-alcohol added in excess, then passing the bottom product into a second reaction zone (11) which contains an acid catalyst and in which the C3- or C4-alkyl tert-butyl ether is separated at elevated temperature into isobutene and primary C3- or C4-alcohol, passing the mixture of isobutene and primary C3- or C4-alcohol into a second distillation zone (13) in which is withdrawn as head product, without inclusion of a scrub with water, isobutene containing not more than 500 ppm by weight of primary C3- or C4-alcohol and as bottom product the primary C3- or C4-alcohol, and recycling the primary C3- or C4-alcohol into the etherification zone (4). <IMAGE> |
