Apparatus for the double bond hydroisomerization of butenes

An apparatus for the preferential conversion to 2-butene of a feed stream containing hydrogen and C4 compounds including 1-butene and 2-butene, comprising:

• a hydroisomerization reactor configured to contain a hydroisomerization catalyst for converting at least a portion of said 1-butene is said feed stream to 2-butene, the hydroisomerization reactor having a feed stream inlet and a reactor outlet,
• a first fractionation column configured to separate said hydroisomerized feed stream into a top stream comprising isobutane and isobutylene and a bottoms stream comprising 2-butene, the first fractionation column having a feed inlet, a top outlet and a bottoms outlet,
• a side draw near the top of said fractionation column above the feed inlet for removing a recycle stream, the side draw being positioned at an elevation in said column at which the 1-butane concentration would be at a maximum if no side draw were withdrawn,
• a second fractionation column positioned downstream from the hydroisomerization reactor and upstream from the first fractionation column to remove C5 and/or heavier components, and
• a recycle inlet for combining said recycle stream with said feed stream upstream from said feed stream inlet.