Abstract: The catalytic cracking catalyst was aged for different duration from 2h to 70 h under the conditions of 800℃, 100 % steam and normal pressure in a fixed fluidized bed aging apparatus to investigate the physical properties changes of the catalyst. Eleven aged catalysts with different aging periods were analyzed by XRD, BET, NH3-TPD and Py-IR and MAT. The results showed that as the aging period increased, the relative crystallinities and the specific surface areas of the catalysts decreased rapidly and then slowly; the ratio of weak L acid to B acid and the ratio of strong L acid to B acid increased first and then decreased; the MAT of the catalyst decreased rapidly and then tended to be flat.

Key words: catalytic cracking, catalyst, aging period, relative crystalinity, pore structure