초록 ▼

Sulfur oxides are removed at least partially from the gaseous regenerator effluent of a fluid catalytic cracking unit operated with feedstock containing sulfur compounds and converted to hydrogen sulfide in the cracking zone by associating sulfur oxides in the gas with at least one rare earth compou

Sulfur oxides are removed at least partially from the gaseous regenerator effluent of a fluid catalytic cracking unit operated with feedstock containing sulfur compounds and converted to hydrogen sulfide in the cracking zone by associating sulfur oxides in the gas with at least one rare earth compound, preferably cerium or a rare earth mixture rich in cerium, supported on discrete particles of alumina. The alumina particles may be a component of particles of a composite fluid cracking catalyst or separate fluidizable entities other than cracking catalyst and physically admixed with the catalyst particles.

대표청구항 ▼

A process of continuous cyclic fluid catalytic cracking with reduced emission of sulfur oxides from regenerator gaseous effluent which comprises (a) contacting a hydrocarbon feedstock containing organic sulfur compounds in the absence of added hydrogen with a circulating inventory comprising crackin

A process of continuous cyclic fluid catalytic cracking with reduced emission of sulfur oxides from regenerator gaseous effluent which comprises (a) contacting a hydrocarbon feedstock containing organic sulfur compounds in the absence of added hydrogen with a circulating inventory comprising cracking catalyst microspheres and separate discrete fludizable attrition-resistant particles of rare earth metal impregnated on dense microspheres of gamma alumina in a reaction zone in a riser cracker at about 900°to 1000°F. for about 0.5 to about 5 seconds to produce lower boiling hydrocarbons and to cause deposition on said catalyst microspheres of solid deactivating sulfur-containing carbonaceous material, said dense microspheres of gamma alumina having been prepared by slurrying particles of alpha alumina monohydrate in an acid solution, spray drying the slurry to form microspheres and heating the resulting microspheres to convert the alumina to gamma form before impregnating rare earth metal thereon; (b) removing said catalyst microspheres and said separate particles containing said deposit from the reaction zone and stripping volatiles therefrom with steam in a stripping zone; (c) regenerating said stripped particles by oxidation at elevated temperature in a regenerating zone at a temperature in the range of about 1100°to about 1400°F. for about 3 to about 120 minutes with combustion of carbon monoxide to carbon dioxide to burn off residual sulfur-containing carbonaceous deposit, producing a gaseous regeneration zone effluent containing oxides of sulfur and (d) removing regenerated catalyst microspheres and said separate particles from said regenerating zone and recycling them to the reaction zone, whereby emissions of oxides of sulfur in said gaseous regeneration zone effluent are reduced substantially as a result of association of oxides of sulfur with said separate particles during step (c) and disassociation of associated oxides of sulfur into a gaseous product consisting essentially of hydrogen sulfide during steps (a) and (b).