Patent ID: 7692057

Claim:
A process for producing lower olefins, which is carried out under the conditions of catalytic cracking olefins and adopts as a feedstock an olefins-enriched mixture containing one or more C4 or higher olefins, comprises the steps of: a) introducing the feedstock firstly enter a first reaction zone to contact with a first crystalline aluminosilicate catalyst having a SiO 2 /Al 2 O 3 molar ratio of at least 10, to thereby produce a first reaction effluent containing lower olefins; b) introducing the first reaction effluent enter in turn at least one second reaction zone to contact with a second crystalline aluminosilicate catalyst having a SiO 2 /Al 2 O 3 molar ratio of at least 10, to thereby produce a second reaction effluent containing lower olefins; and c) separating lower olefins from the second reaction effluent; wherein the reaction temperature in the first reaction zone is lower by 10 to 80° C. than that in the second reaction zone and the WHSV of the first reaction zone is higher by 5-15 hr −1 than that of the second reaction zone.