Ultra-stable rare earth Y-type molecular sieve and preparation method therefor

An ultra-stable rare earth type Y molecular sieve, wherein the ultra-stable rare earth type Y molecular sieve comprises 1% to 20% by weight of rare earth oxide and not more than 1.2% by weight of sodium oxide, and has a crystallinity of 51% to 69% and a lattice parameter of 2.449 nm to 2.469 nm;

• wherein the ultra-stable rare earth type Y molecular sieve is prepared from a NaY molecular sieve as a raw material, the preparation process of the ultra-stable rare earth type Y molecular sieve includes subjecting the raw material to a rare earth exchange and a dispersing pre-exchange to give a molecular sieve slurry, subjecting the molecular sieve slurry to filtration, washing, and a first calcination to afford a “one-exchange one-calcination” rare earth sodium Y molecular sieve, and subjecting the “one-exchange one-calcination” rare earth sodium Y molecular sieve to an ammonium salt exchange for sodium reduction and a second calcination, so as to obtain the ultra-stable rare earth type Y molecular sieve, wherein the order of the rare earth exchange and the dispersing pre-exchange is not limited, and the rare earth exchange and the dispersing pre-exchange are consecutively conducted without a calcination process therebetween;
• wherein the dispersing pre-exchange comprises adjusting a slurry of the molecular sieve to a solid content of 80 to 400 g/L and adding 0.2% to 7% by weight of a dispersing agent, wherein dispersing pre-exchange is carried out at an exchange temperature of 0 to 100° C. for 0.1 to 1.5 h;
• 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.