Improved systems and methods for producing propylene from olefins including isobutylene is disclosed. The improvements combine streams containing co-produced 1-butene, 2-butene, butadiene, and heavy olefins (C5+) exiting both a metathesis reactor and a skeletal isomerization reactor in a gasoline fractionation tower to remove the heavy olefins. The C4-containing distillate from the gasoline fractionation tower is then fed to a hydroisomerization unit to form mono-olefins and 2-butene. The resulting 2-butene rich stream can then be utilized in metathesis reactions to increase the production of propylene while increasing the lifetime of the metathesis catalyst.