Abstract: In order to reduce the olefin content in stabilized gasoline of FCC unit (MIP process) to meet the national VIA standard of vehicle gasoline, the optimization of operation conditions was carried out in a 4.8 Mt/a FCC unit. The results showed that the volume fraction of olefins in stabilized gasoline decreased by 2.4 percentage points by increasing the temperature of the first reaction zone by 4 ℃; the increase of micro-reaction activity of the equilibrium catalysts of 2.8 units led to a reduction of olefin content by 4.6 percentage points; recycling the crude gasoline at a rate of 15 t/h resulted in a reduction of olefin content by 1.3 percentage points, and increasing the final boiling point of stabilized gasoline by 4℃ would decline the olefin content by 0.3 percentage points. The main principles of technical measures are to enhance the hydrogen transfer reaction and the small molecule olefins cracking reaction. These reactions are secondary reactions and result in a high coke yield. The large oil refining enterprises should take the blending pool of gasoline into consideration and choose the appropriate olefin content of the stabilized gasoline to get the comprehensive benefits.

Key words: stabilized gasoline, olefin, hydrogen transfer, catalytic cracking