The properties of the ultrastable Y zeolite (USY) over the Y zeolite have the following changes:
(1) Thermal stability and hydrothermal stability improve;
(2) lower hydrogen transfer capacity, higher olefin content in gasoline and higher octane number of gasoline;
(3) coke yield reduction, improved coke selectivity;
(4) the cracking activity decreases, the gasoline yield decreases, the corresponding diesel yield increases, and the total liquid yield increases.