Abstract: The hydrogen-donating indexes of the three narrow fractions of FCC recycle oil were measured. Among these fractions, the one which has the highest hydrogen-donating index was chosen to be used as hydrogen donor after being hydro-treated. The hydrogen-donating effect of the hydro-treated fraction was investigated in pilot tests. The results showed that the fraction (IBP-400℃) has the best hydrogen-donating capacity among the three narrow fractions of FCC recycle oil, and the hydrogen-donating capacity can be further improved by hydrotreatment. When the fraction (IBP-400 ℃) hydrotreated was used as hydrogen donor, the liquid yield can increase by 1.32% and coke yield can decrease by 2.45%.

Key words: coking, hydrogen donor, catalytic cracking, recycle oil, narrow fraction, hydrotreatment, hydrogen-donating capacity