Process for the preparation or lower olefins

Abstract

Disclosed is a process for producing lower olefins, comprising: (A) a step wherein a mixed fluid (I) containing dimethyl ether (DME) and methanol in a specific ratio is separated into a gas component (II) and a liquid component (III) under high pressure, then the gas component (II) is separated into an off-gas and dimethyl ether, and the separated dimethyl ether is allowed to join the liquid component (III) to obtain a liquid component (IV) containing DME and methanol in a specific ratio, and (B) a step wherein the pressure of the liquid component (IV) is released, and then the liquid component (IV) is introduced into an olefin production reactor to produce a lower olefin fraction (V). According to the invention, lower olefins are produced from a mixed fluid (I) containing DME and methanol in a specific ratio. Therefore, the reaction to synthesize an oxygen-containing compound and the reaction to produce lower olefins can be both carried out under milder conditions as compared with the case where lower olefins are produced from only methanol, and hence the energy and the equipment cost can be greatly reduced. According to the invention, further, lower olefins containing ethylene and propylene in a desired ratio can be efficiently produced.

Dependencies are inferred from the claim text.