A process for producing propylene from ethylene and a feed stream comprising 1-butene, 2-butene, n-butane, and isobutane is disclosed. A butenes stream (1-butene and 2-butene) is produced from the feed stream by removing the paraffins. The butenes stream is reacted in the presence of an isomerization catalyst to produce an isomerized stream with increased concentration of 2-butene. The isomerized stream is reacted with ethylene in the presence of a metathesis catalyst to produce a reaction mixture comprising propylene; the propylene may be isolated from the reaction mixture by distillation. The removal of paraffins from the feed stream improves the catalyst productivity and the plant throughput.