Patent ID: 7692056

Claim:
A process for producing lower olefins herein, which is carried out under the conditions of catalytic cracking methanol and dimethyl ether and the presence of diluting gas, and adopts as a feedstock methanol, dimethyl ether or their mixture, 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 weight ratio of the diluting gas to the feedstock is 0.01-6:1, the reaction pressure in the first reaction zone is−0.1-1 MPa, and the reaction pressure in the second reaction zone is −0.09-0.5 MPa, and the reaction temperature in the first reaction zone is lower by 30 to 150° C. than that in the second reaction zone, and the WHSV of the first reaction zone is higher by 3-20 hr −1 than that of the second reaction zone.