Bayerite alumina clad zeolite and cracking catalysts containing same

A particulate cracking catalyst suitable for use in fluid catalytic cracking of petroleum feedstocks, said catalyst comprising particles of crystalline zeolite having a coating on the surface of the particles comprising bayerite phase alumina.

A method of forming bayerite alumina coated zeolite particles comprising forming an aqueous slurry having an acidic pH of less than 7 comprising aluminum ion-containing solution and zeolite particles, contacting said slurry with an aqueous solution of a strong base at a concentration to cause the resultant slurry to have a pH of at least 10, and allowing bayerite alumina to precipitate onto the zeolite particles.

A method of forming bayerite alumina coated zeolite particles comprising forming an aqueous slurry having an alkaline pH of greater than about 12 comprising aluminum ion-containing solution and zeolite particles, contacting said slurry with carbon dioxide for a sufficient time to cause the resultant slurry to have a pH of from about 10 to 11.5, and allowing bayerite alumina to precipitate onto the zeolite particles.

A bayerite alumina-coated zeolite particulate product formed by initially mixing a solution of an aluminum ion source with a slurry of zeolite to provide a slurry having a pH of less than 7, contacting the resultant slurry with a strong basic material in sufficient amount to cause the resultant slurry to have a pH of at least 10, and allowing bayerite alumina to precipitate onto the zeolite particles.

A bayerite alumina coated zeolite particles formed by initially forming an aqueous slurry having a pH of at least about 12 comprising aluminum ion-containing solution and zeolite particles at an elevated temperature of up to 49° C., contacting said slurry with CO2 to cause the resultant slurry to have a pH of at least 10, and allowing bayerite alumina to precipitate onto the zeolite particles.