A process is disclosed for preparing a C4 stream for feeding to an
alkylation
process which reacts isobutane with butene to produce isooctane. The C4 stream
is treated in a first distillation column reactor to remove dienes and mercaptans
and separate out any C5's which might be present. The treated C4's
are then fed to a second distillation column reactor that concurrently isomerizes
1-butene to 2-butene and splits the normal C4's from the iso C4's.
The iso C4's are then fed to a third distillation column reactor where
a portion of the isobutene is saturated to isobutane. The C4's from
the isomerization/splitter are combined with the C4's from the hydrogenation
unit and fed to a cold acid alkylation unit. The third distillation column may
also oligomerize a portion of the isobutene to diisobutene in the upper end which
is saturated in the bottom of the column to isooctane.
