Disclosed herein is a process for upgrading a raffinate butene (C4 Raffinate) stream to propylene which can produce polymer grade propylene (PGP) by a metathesis process, without consuming fresh ethylene as a feedstock. By recycling ethylene byproduct in the metathesis equilibrium, propylene selectivity can be further improved without negatively impacting butene conversion. Additionally, upon PGP separation, this technology can provide an effluent acceptable for alkylate production by achieving a balanced butene conversion and heavies coproduction. The disclosed process is a relatively low temperature process which can be deployed as a drop-in option for conventional ethylene/butene metathesis unit and provide additional flexibility to existing operations to balance the supply and demand of C2-C4 light olefins.