Process for the catalytic cracking of vanadium-containing feedstocks

A process for the catalytic cracking of a vanadium-containing hydrocarbon feedstock which process comprises contacting said hydrocarbon feedstock with a cracking catalyst under cracking conditions in the substantial absence of added molecular hydrogen in a cracking zone to convert components of said feedstock into lower molecular weight constituents wherein said cracking catalyst contains less than about 7800 ppmw vanadium, calculated as the metal and based on the carbon-free weight of said catalyst, and said cracking catalyst comprises:

• (a) a crystalline aluminosilicate zeolite dispersed in a matrix;
• and
• (b) a vanadium passivating agent comprising gadolinium or compounds thereof, said passivating agent being present in said catalyst in an amount greater than about 1.0 weight percent, calculated as the oxide of said vanadium passivating agent and based on the carbon-free weight of said catalyst, and in an amount such that the weight ratio of said passivating agent to any lanthanum present in said catalyst, calculated based on the respective oxides, is greater than about 1.0, and wherein the total rare earth content of said catalyst is greater than about 2.0 weight percent, calculated based on the respective rare earth oxides and on the carbon-free weight of said catalyst.

A process for the catalytic cracking of a vanadium-containing hydrocarbon feedstock which process comprises contacting said hydrocarbon feedstock with a cracking catalyst under cracking conditions in the substantial absence of added molecular hydrogen in a cracking zone whereby vanadium deposits onto said catalyst and components of said feedstock are converted into lower molecular weight constituents, said catalyst comprising:

• (a) a crystalline aluminosilicate zeolite dispersed in a matrix;
• and
• (b) greater than about 1.0 weight percent cerium, calculated as CeO.sub.2 and based on the carbon-free weight of said catalyst, whereby said cerium passivates vanadium which deposits onto said catalyst and wherein a sufficient amount of said cerium is present such that the weight ratio of cerium to any lanthanum, calculated as CeO.sub.2 /La.sub.2 O.sub.3, present in said catalyst is greater than about 2.0 and the total rare earth content of said catalyst is greater than about 2.0 weight percent, calculated based on the respective rare earth oxides and on the carbon-free weight of said catalyst.