Abstract: Two alumina materials prepared in lab and three industrial alumina materials before and after hydrothermal aging treatment were characterized by XRD、XRF、BET、FT-IR and NH3-TPD, and evaluated in a heavy oil micro reactor. The results indicated that the selected alumina materials possess pseudo-boehmite structure and average pore diameter of 5～16 nm belonging to mesopore. All the materials only have Lewis acid centres. The preparation method leads to an obvious difference in crystallinity, pore parameter, acidic property, hydrothermal stability and cracking activity. The cracking property and product distribution depend on both pore parameter and acidic property of the alumina material after hydrothermal aging treatment, and the effect degree of pore parameter and acidic property differs from each other in size of pore diameter. For the alumina material with pore diameter about 10 nm, the pore structure is the main influence factor. When the pore diameter increases to 13～25 nm, the influence of total acid content is relatively higher than the pore diameter.

Key words: porous material, pore diameter, acidity, FCC, catalytic activity