Heavy oil catalytic cracking catalyst and preparation method therefor

A heavy oil catalytic cracking catalyst, characterized in that the catalyst comprises 2% to 50% by weight of an ultra-stable rare earth type Y molecular sieve, 0.5% to 30% by weight of one or more other molecular sieves, 0.5% to 70% by weight of clay, 1.0% to 65% by weight of high-temperature resistant inorganic oxides, and 0.01% to 12.5% by weight of rare earth oxide;

• wherein the ultra-stable rare earth type Y molecular sieve is an ultra-stable rare earth type Y molecular sieve having 0.5% to 25% by weight of rare earth oxide, not more than 1.2% by weight of sodium oxide, a crystallinity of 40% to 75%, and a lattice parameter of 2.449 nm to 2.472 nm;
• and
• wherein the ultra-stable rare earth type Y molecular sieve is prepared from a NaY molecular sieve as a raw material by a preparation method in which a molecular sieve slurry of the raw material is subjected to a rare earth exchange and a dispersing pre-exchange, then the molecular sieve slurry is further filtered, washed, and subjected to a first calcination to produce an intermediate rare earth sodium Y molecular sieve, wherein the order of the rare earth exchange and the dispersing pre-exchange steps is not limited,
• the rare earth exchange and the dispersing pre-exchange being consecutively conducted without a calcination process therebetween, and the intermediate rare earth sodium Y molecular sieve then being subjected to an ammonium salt exchange for sodium reduction and a second calcination so as to obtain an ultra-stable rare earth type Y molecular sieve;
• wherein the dispersing pre-exchange refers to a process of adjusting the molecular sieve slurry's concentration to a solid content of 80 to 400 g/L and adding 0.2% to 7% by weight of a dispersing agent to carry out dispersing pre-exchange at an exchange temperature of 0° C. to 100° C. for 0.1 to 1.5 h;
• wherein the dispersing agent in the dispersing pre-exchange process is selected from one or more of sesbania gum powder, boric acid, urea, ethanol, polyacrylamide, acetic acid, oxalic acid, adipic acid, formic acid, hydrochloric acid, nitric acid, citric acid, salicylic acid, tartaric acid, benzoic acid, and starch;
• and
• wherein no ammonium salt is used in the rare earth exchange or the dispersing pre-exchange.