Abstract: Two catalytic cracking catalysts (numbered LDO-75, LB-5) prepared by semi-synthesis process and in-situ crystallization process were respectively subjected to high temperature hydrothermal treatment (numbered LDO-75-T, LB-5-T). The pore structures and hydrothermal stabilities of the two catalysts before and after high temperature hydrothermal treatment were investigated. The results showed that the pore volume and specific surface area of LB-5 were 0.35 cm3/g and 307.3 m2/g, respectively, higher than those of LDO-75 with 0.27 cm3/g and 214.1m2/g. The most probable pore size of LDO-75 and LB-5 were 3.8 nm and 6.3 nm, respectively. Although the crystallinity of Y zeolite in LB-5 catalyst was similar to LDO-75 catalyst, the microporous specific surface area of LB-5 was 216.0 m2/g, which was significantly higher than LDO-75. The microporous surface area retention rates of LDO-75 and LB-5 were 44.4% and 25.1%, respectively, after hydrothermal treatment, which indicated that LB-5 had unstable microporous structure. After hydrothermal treatment, the pore volume around 3.8 nm pore diameter of LDO-75-T increased, the pore volume around 6.3 nm of LB-5-T decreased, while that in range of 10-50 nm diameters increased.

Key words: catalytic cracking, semi-synthetic, in-situ crystallization, pore structure, hydrothermal stability