Hydrocarbon cracking catalyst

Claim 1

In an improved method for catalytically cracking hydrocarbons wherein the production of coke is minimized, the improvement comprising contacting a hydrocarbon feedstock with a catalyst comprising a catalytically active, coke selective zeolite admixed with an inorganic oxide matrix, and recovering cracked hydrocarbons of lower molecular weight, said zeolite being prepared by: a. exchanging a sodium Y zeolite having a silica to alumina ratio of about 3.5 to 6 with an ammonium salt to reduce the Na 2 O content thereof to less than 4 percent by weight; b. exchanging said zeolite with a solution of rare earth ions to provide a rare earth content expresses as rare earth oxide of about 0.5 to 4 percent by weight; c. washing said zeolite to remove excess salts; d. heating said zeolite to a temperature of about 700° to 1600° F.; e. contacting said zeolite with a dilute solution of a mineral acid to remove alumina therefrom and thereby increase the silica to alumina ratio to a range of about 7 to 20; f. exchanging the zeolite of step e. with a solution of metal ions selected from the group consisting of rare earth and magnesium ions to provide a total metal ion content expressed as metal oxides of from about 1 to 10 percent by weight.