Abstract: A process for regenerating a spent catalyst having coke deposits thereon in a catalyst regeneration vessel having a dense phase and a dilute phase, wherein the process comprises the steps of: (a) contacting the spent catalyst with a primary oxygen-containing gas in the dense phase, thereby combusting the coke, resulting in the formation of a combustion gas comprising nitrogen oxides and carbon monoxide which further reacts, thus reducing a majority of the nitrogen oxides to form elemental nitrogen; and (b) contacting the combustion gas with a secondary oxygen-containing gas, and typically a shield gas, at a location just above the interface between the dense phase and the dilute phase and also in the dilute phase, thereby oxidizing the remaining CO to CO2 without significant temperature rise in the dilute phase due to the after burn.

Abstract: A process for regenerating a spent catalyst having coke deposits thereon in a catalyst regeneration vessel having a dense phase and a dilute phase, wherein the process comprises the steps of: (a) contacting the spent catalyst with a primary oxygen-containing gas in the dense phase, thereby combusting the coke, resulting in the formation of a combustion gas comprising nitrogen oxides and carbon monoxide which further reacts, thus reducing a majority of the nitrogen oxides to form elemental nitrogen; and (b) contacting the combustion gas with a secondary oxygen-containing gas, and typically a shield gas, in the dilute phase, thereby oxidizing the remaining CO to CO2 without significant temperature rise in the dilute phase due to the after bum.