Method and system for treating catalytic cracking reaction product and use thereof

A method for treating a catalytic cracking product, comprising the steps of:

• i) carrying out a first fractionation on a catalytic cracking oil gas or catalytic cracking gasoline from a catalytic cracking reactor to obtain a heavy gasoline and optionally a light gasoline, wherein the light gasoline has an initial boiling point of about 20-40° C., and a final boiling point of about 80-100° C., the heavy gasoline has an initial boiling point of about 80-100° C., and a final boiling point of about 200-250° C.;
• ii) carrying out a second fractionation on the heavy gasoline to obtain a heavy fraction of gasoline and optionally a middle fraction of gasoline, wherein the middle fraction of gasoline comprises C6-C8 light aromatics, has an initial boiling point of about 80-100° C., and a final boiling point of about 120-150° C., and the heavy fraction of gasoline comprises C9+ aromatics, has an initial boiling point of about 120-150° C., and a final boiling point of about 200-250° C.;
• iii) optionally, carrying out an aromatics extraction on the middle fraction of gasoline to obtain BTX aromatics and an aromatic raffinate oil;
• iv) sending the heavy fraction of gasoline to a fluidized reactor to contact with a dealkylation catalyst for dealkylation in the presence of hydrogen to obtain a dealkylated liquid product and a spent dealkylation catalyst;
• and
• v) recycling said dealkylated liquid product to step ii) to conduct the second fractionation with said heavy gasoline.