Abstract: Hydrocarbon feedstocks containing relatively high levels of vanadium contaminants are converted by catalytic cracking to products of lower average molecular weight by contacting the feedstock with a catalyst comprising (1) a crystalline aluminosilicate zeolite dispersed in a matrix and (2) a vanadium passivating agent selected from the group consisting of cerium, praseodymium, neodymium, gadolinium and compounds thereof. The passivating agent is present in the catalyst in an amount greater than about 1.0 weight percent, calculated as the oxide of the vanadium passivating agent and based on the carbon-free weight of the catalyst. The passivating agent is also present in an amount such that the weight ratio of the passivating agent to any lanthanum present in the catalyst, calculated based on the respective oxides, is greater than about 1.0. The total weight of all rare earths present in the catalyst is greater than about 2.

Abstract: A sulfur sorbent for use in reducing the emissions of sulfur oxides from regenerators of cyclic catalytic cracking units comprises a rare earth component or mixture of rare earth components in combination with a porous, inorganic refractory oxide component. The rare earth components used as a portion of the sorbent are preferably derived from the mineral bastnaesite by treating the bastnaesite to remove at least 50 weight percent of its fluorine, calculated as the element. The activity of the sulfur sorbent for removing sulfur oxides during catalytic cracking processes is increased to unexpectedly high levels by including in the composition cobalt or other transition metal component comprising an element selected from Group IB, Group IIB Group IVA, Group VA, Group VIA, Group VIIA, and Group VIII of the Periodic Table of Elements.

Abstract: A sulfur sorbent for use in reducing the emissions of sulfur oxides from regenerators of cyclic catalytic cracking units comprises a rare earth component or mixture of rare earth components in combination with a porous, inorganic refractory oxide component. The rare earth components used as a portion of the sorbent are preferably derived from the mineral bastnaesite by treating the bastnaesite to remove at least 50 weight percent of its fluorine, calculated as the element. The activity of the sulfur sorbent for removing sulfur oxides during catalytic cracking processes is increased to unexpectedly high levels by including in the composition cobalt or other transition metal component comprising an element selected from Group IB, Group IIB, Group IVA, Group VA, Group VIA, Group VIIA, and Group VIII of the Periodic Table of Elements.