Catalytic promoters for the catalytic cracking of hydrocarbons

Disclosed is a catalytic promoter for fluid catalytic cracking of hydrocarbons, comprising a HZSM-5 zeolite in an amount of 5-65 wt% based on the total weight of the catalytic promoter, said zeolite being modified with Zn and at least one element selected from the group consisting of P, Ga, Al, Ni and rare earth elements, the combined amount of said modifying elements being 0.01-10.37 wt% based on total weight of said modified HZSM-5 zeolite. A reduced olefin content in gasoline from catalytic cracking process, an increased gasoline octane number and an increased lower olefin yield can be obtained using said catalytic promoter.