Abstract: Kaolin microsphere (or powder) and metakaolin powder (or microsphere) were used as raw materials, the corresponding kaolin microsphere and metakaolin powder were obtained by high temperature and medium temperature calcination respectively. Y zeolite was synthesized and characterized by XRD, N₂ adsorption-desorption and SEM. The results showed that the crystallinity of metakaolin was higher in the mixed crystallization of kaolin and metakaolin. When the mass ratio of liquid to solid was 2.5 and the mass ratio of kaolin microsphere to metakaolin powder was 1:1, the crystallinity of the metakaolin product (named PK-1) was 81%, and the mesoporous pore volume and external surface area were 0.13 cm³/g and 53.3 m²/g respectively, which were higher than those of NaY (0.02 cm³/g and 28.8 m²/g). The grain size of PK-1 was 300-600 nm. ACE evaluation showed that the catalyst prepared by using PK-1 had better heavy oil conversion ability and better coke selectivity than by commercial NaY zeolite.

Key words: kaolin, in-situ crystallization, Y zeolite, mesoporous, catalytic cracking