Patent ID: 7060866

Claim:
A method of separating dimethyl ether from an olefin stream, comprising: contacting oxygenate with a molecular sieve catalyst to form an olefin stream, wherein the olefin stream contains ethylene, ethane, propylene, propane, and dimethyl ether; and separating the olefin stream into a first fraction and a second fraction at a pressure of at least 200 psig in a distillation column having trays, wherein the first fraction contains at least a majority of the ethylene and propylene present in the olefin stream, the second fraction contains at least a majority of the dimethyl ether present in the olefin stream, and the olefin stream being separated further contains water in an amount not greater than 5,000 wppm so that free water formation or gas hydration does not significantly impede the separation.