Abstract: A process for the removal of oxidizable sulfur compounds from a waste gas which comprises:(a) mixing a waste gas containing compounds oxidizable to sulfur oxides with molecular oxygen and oxidizing said compounds to sulfur oxides;(b) contacting the oxidized gas with a metal oxide absorbent capable of absorbing sulfur oxides at a temperature of between about 100.degree. C. and 800.degree. C., and absorbing sulfur oxides with said metal oxide absorbent;(c) simultaneously, in the presence of a hydrocarbon cracking catalyst and at a temperature of between about 375.degree. C. and about 1,200.degree. C., cracking a hydrocarbon, regenerating the spent metal oxide absorbent and contacting the absorbent with steam to form hydrogen sulfide which can be separated from the cracked hydrocarbon and recovered as elemental sulfur.

Abstract: A cyclic fluidized catalytic cracking process is operated with a cracking catalyst which is modified with one or more metal oxides capable of reacting with sulfur oxides in the regeneration zone wherein the catalyst is regenerated under conditions which result in substantially complete conversion of carbon monoxide to carbon dioxide. Tail gases and flue gases from refinery furnaces which contain carbon monoxide and sulfur oxides are conveyed to the regeneration zone where they are scrubbed by the modified catalyst. The sulfur oxides are absorbed and the carbon monoxide is converted to carbon dioxide in the regeneration zone.