PROCESS FOR THE PREPARATION OF LOWER OLEFINS

摘要

A process for the preparation of lower olefins which comprises the step (A) of separating in a high-pressure state a mixed fluid (I) containing dimethyl ether (DME) and methanol at a specified ratio into a gas component (II) and a liquid component (III), separating the gas component (II) into an off-gas an d dimethyl ether, and then making this dimethyl ether join the liquid componen t (III) to obtain a liquid component (IV) containing DME and methanol at a specified ratio and the step (B) of subjecting the liquid component (IV) to depressurization and then introducing it into a reactor for the preparation of olefins to form a lower olefin fraction (V). According to this process, lowe r olefins are prepared from a mixed fluid (I) containing DME and methanol at a specified ratio, and therefore both the synthesize of oxygen-containing compounds and the formation of olefins can be carried out under milder conditions than those employed in preparing lower olefins from methanol alon e to thereby reduce the costs of energy and equipment remarkably. Further, the process enables efficient production of lower olefin mixtures containing ethylene and propylene at desired ratios.