Described is an apparatus for, and a method of, recovering linear butenes from a mixed feed comprising providing a first mixed feed comprising linear butenes and isobutene; contacting the first mixed feed with an oligomerization catalyst such as an MWW family zeolite in a first oligomerization reactor to produce a second mixed feed comprising the linear butenes, C8 olefins and higher oligomers, and a reduced amount of isobutene relative to the first mixed feed; and separating the second mixed feed to produce a first effluent of first purified linear butenes, and a second effluent of C8 olefins and higher oligomers. The oligomerization reactor may be a converted isobutene-to-methyl-t-butylether reactor.