Research progress of coke deposition on catalyst during methanol conversion to olefins

The paper introduces the mechanism of coke deposition over SAPO-34 molecular sieve catalyst used for methanol to olefins reaction，and the effect of catalyst physicochemical characteristics and reaction process condition on coking behavior. The researches on kinetics of coke formation and coke combustion are outlined. Coke species formed on SAPO-34 are mainly polyaromatic species，such as anthracene，phenanthrene and pyrene. The deactivation rate can be attenuated when acidity density and size of molecular sieve are decreased properly. Carbon deposition exponentially increases when reaction temperature increases. Rapid carbon formation is observed in the initial phase of reaction and then rate of carbon deposition decreases. Coke deposition decreases as the ratio of catalyst to methanol increases. Coke formation can be decreased by the presence of water in the feed，but the effect of water weakens gradually with the progress of the reaction. Coke combustion rate is directly proportional to oxygen pressure and coke amount. The review provides reference for improving catalyst performance，prolonging catalyst life time and improving olefins selectivity to optimize the reaction and regeneration process condition.