| 摘要 |
A method for increasing the ratio of 2-methyl-2-butene (2MB2) to 2-methyl-1-butene (2MB1) in isoamylenes involves fractionating a feedstream containing tertiary amyl methyl ether (TAME) and isoamylenes including 2MB2 and 2MB1 in a ratio of about 2:1 to effect a separation between an overhead hydrocarbon fraction of isoamylenes including 2MB2 and 2MB1 in a ratio of about 1:1, a bottoms fraction including TAME, and a sidestream hydrocarbon fraction consisting essentially of isoamylenes including 2MB2 and 2MB1 in a ratio of about 6 to 12:1, recovering the sidestream hydrocarbon fraction, and recycling the overhead hydrocarbon fraction of isoamylenes to form a mixture which is subsequently reacted to form the feedstream. Prior to fractionation, the feedstream is formed by passing isoamylene, and optionally TAME, in a vapor phase over an ether cracking catalyst which isomerizes isoamylene and converts 2MB1 to 2MB2, i.e., the feedstream for fractionating, which contains 2MB2 and 2MB1 in a ratio of 2 to 5:1. A method for converting 2-methyl-1-butene to 2-methyl-2-butene which may be used to form the feedstream for fractionating involves providing a hydrocarbon stream comprising isoamylenes including 2MB1 and 2MB2 in a ratio of within the range of 1:1 to 5, adding about TAME to the isoamylenes to form a mixture which is passed in the liquid phase at a temperature and a LHSV which favors isomerization over an acidic ion exchange resin catalyst to produce a reaction product including 2MB1, 2MB2 in a ratio of 1:6 to 12, and TAME.
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