Catalytic conversion method and system for producing low-carbon olefins and light aromatic hydrocarbons from hydrogenated diesel oil

The invention provides a catalytic conversion method for producing low-carbon olefins and light aromatic hydrocarbons from hydrogenated diesel oil, which comprises the following steps: S1, contacting the hydrogenated diesel oil with a first catalyst in a first riser reaction zone, and carrying out a first catalytic conversion reaction to obtain a first oil agent mixture; s2, the first oil agent mixture is introduced into a second riser reaction zone to be in contact with a second catalyst, a second catalytic conversion reaction is conducted, and a second oil agent mixture is obtained; s3, carrying out gas-solid separation and steam stripping on the second oil agent mixture in a settler to obtain an oil-gas product and a mixed spent catalyst; s4, the mixed spent catalyst is introduced into a catalyst separation device for separation, and a first spent catalyst and a second spent catalyst are obtained. The invention also provides a catalytic conversion system. According to the present invention, the suitable re