Abstract: The catalytic cracking and thermal cracking reactions of atmospheric gas oil（AGO）were investigated in a small fixed fluidized bed reactor at 520－680 °C using acid catalyst and quartz sand respectively. Compared with thermal cracking, the catalytic cracking of AGO had the advantages in increasing its conversion, decreasing the dry gas yield and increasing the LPG yield, which could reduce the ethylene yield by 1.67－3.78 percentage points, increase propylene yield by 5.23－9.12 percentage points and the butene yield by 3.32－7.94 percentage points respectively, so as to the BTX yield. The content of methane and ethylene in the dry gas of catalytic cracking and thermal cracking of AGO had the same change trend with reaction temperature, but the volume fraction of hydrogen in catalytic cracking dry gas was greater than ethane, while the volume fraction of hydrogen in thermal cracking dry gas was lower than ethane. When the reaction temperature was higher than 600 ℃, the mole ratio of C2H4/CH4 of catalytic cracking dry gas was less than the optimal distribution value of thermal cracking dry gas（0.82）. The changing trends of n-alkane, isoalkane, olefin and aromatic in the two kinds of cracking gasoline were similar, but the changing trend of naphthene was opposite. The naphthene in catalytic cracking gasoline decreased with the increase of reaction temperature, while the naphthene in thermal cracking gasoline increased with the increase of reaction temperature.

Key words: atmospheric gas oil, deep catalytic cracking, thermal cracking, light olefins, light aromatics