Patent ID: 8304594

Claim:
A process for increasing ethylene and/or propylene yield during conversion of oxygenates using a system comprising a reactor and a regenerator, wherein the reactor comprises a fluidized bed reactor and a riser reactor, comprising: (a) feeding a feedstock comprising an oxygenate to the lower reaction zone of the fluidized bed reactor, wherein the feedstock being converted to a reaction product comprising ethylene, propylene and C 4 + hydrocarbon in the presence of a catalyst, after separated from the catalyst, the reaction product entering into a subsequent separation section to be further separated into a C 4 + hydrocarbon stream, an ethylene product and a propylene product; (b) feeding the separated C 4 + hydrocarbon stream to the lower reaction zone of the riser reactor, wherein the separated C 4 + hydrocarbon stream being cracked to a reaction product comprising ethylene and propylene in the presence of a catalyst, after passing the upper sedimentation section of the fluidized bed reactor, the reaction product entering into the subsequent separation section, wherein the catalyst in the riser reactor being a mixture of the deactivated catalyst from the fluidized bed reactor and the regenerated catalyst from the regenerator with a ratio between their mass rates in the range of 0.2-5; and (c) the catalyst to be regenerated entering into the regenerator from the fluidized bed reactor after stripped, and the regenerated catalyst having an average carbon deposition of less than 6 wt % relative to its total weight and being recycled to the riser reactor.