Small-grain ZSM-5 catalytic cracking catalyst and preparation method thereof

The invention belongs to the technical field of catalysts, and particularly relates to a small-grain ZSM-5 catalytic cracking catalyst and a preparation method thereof. According to the invention, the clay raw material is subjected to acid extraction to extract part of Al2O3 and impurities from the skeleton of the first clay to improve the SiO2/Al2O3 ratio of the skeleton, so that the pore structure is improved, the residual SiO2 can be activated in advance, and subsequent in-situ growth of ZSM-5 is facilitated; the extracted active Al2O3 is completely utilized, so that the loss and waste of active aluminum are avoided, and the wear resistance of the small-grain ZSM-5 catalytic cracking catalyst is also improved. Moreover, the prepared small-grain ZSM-5 catalytic cracking catalyst is high in ZSM-5 zeolite content, developed in mesopores, fine in grain and high in MAT micro-reactivity, and can greatly improve the yield of low-carbon olefins (ethylene and propylene) and liquefied gas when being used for catalyt