Process for controlling sulfur oxides using an alumina-impregnated catalyst

Claim 1

In a process for cracking hydrocarbons in the absence of added molecular hydrogen wherein a nonzeolitic cracking catalyst including of at least one acidic cracking component from the group consisting of silica-containing nonzeolitic crystalline refractory inorganic oxides and silica-containing amorphous refractory inorganic oxides is cycled between a cracking zone and a catalyst regeneration zone, a sulfur-containing hydrocarbon stream is cracked in contact with said catalyst in said cracking zone, and a sulfur-containing flue gas is formed in said regeneration zone by burning sulfur-containing coke off said nonzeolitic catalyst with an oxygen-containing gas, the method for reducing the amount of carbon monoxide and sulfur oxides in said flue gas which comprises: (a) heating particles of said nonzeolitic cracking catalyst to a temperature between 800° F. and 1500° F.; (b) impregnating the resulting nonzeolitic catalyst particles with an amount of an aluminum compound sufficient to add from 0.1 to 25 weight percent aluminum, calculated on an elemental metal basis, to said nonzeolitic catalyst particles; (c) cycling the resulting impregnated nonzeolitic catalyst particles between said cracking zone and said regeneration zone in said catalytic cracking system; (d) reacting sulfur oxides in said flue gas with the added aluminum in said catalyst particles to form a sulfur-containing solid in said catalyst particles in said regeneration zone; and (e) forming hydrogen sulfide in said cracking zone by contacting said hydrocarbon feed with said sulfur-containing solid in said catalyst particles and removing the resulting hydrogen sulfide from said cracking zone with said fluid products.