A process is described for producing an olefins stream from a first vapor effluent stream from an oxygenate to olefin conversion reaction, said first vapor effluent stream comprising C.sub.2 and C.sub.3 olefins, C.sub.4 hydrocarbons, and C.sub.2 to C.sub.6 carbonyl compounds. In the process, the temperature and pressure of the first vapor effluent stream are adjusted to produce a second vapor effluent stream having a pressure ranging from about 100 psig to about 350 psig (790 to 2514 kPa) and a temperature ranging from about 70.degree. F. to about 120.degree. F. (21 to 49.degree. C.), said second vapor effluent stream containing about 50 wt. % or more C.sub.4 hydrocarbons based upon the total weight of C.sub.4 hydrocarbons in the first vapor effluent stream. The second vapor effluent stream is then washed with a liquid alcohol-containing stream to produce a third vapor effluent stream, whereafter the third vapor effluent stream is washed with liquid water to provide a fourth vapor effluent stream comprising the C.sub.2 and C.sub.3 olefins and about 1.0 wt. % or less C.sub.2 to C.sub.6 carbonyl compounds.