The fraction compositions, group compositions and structure compositions of
seven catalytic stocks were determined by means of vacuum distillation, ma
ss spectrum, element analysis and molecular mass measurement. The effects o
f the compositions of different catalytic stocks on catalytic cracking reac
tions were discussed. It is shown that tae gum and asphaltene in the seven
catalytic stocks were not very high except residual oil; The saturated hydr
ocarbon in the seven were all higher; Aromatic contents were lower except s
lurry oil and recycle oil, therefore, the seven catalytic stocks except slu
rry oil and recycle oil are all good feedings to catalytic cracking unit. T
he results also show Liaohe oil turns heavier from low sulphur middle-paraf
fin base to low sulphur naphthene-middle base.