NOx control during multistage combustion

Claim 1

In a Fluidized Catalytic Cracking (FCC) process wherein conventional FCC catalyst contacts conventional FCC feedstocks in a conventional FCC reactor to produce cracked products and coked catalyst which is regenerated in a conventional regenerator comprising a first dense bed coke combustor to which air or an oxygen-containing gas is added to produce at least partially regenerated catalyst and combustion gas which rise from the first dense bed and through a dilute phase transport riser to form a second dense bed of regenerated catalyst and flue gas, and the regenerated catalyst is recycled to the FCC reactor, the improvement comprising reducing NO x emissions and achieving substantially complete carbon monoxide combustion by selective addition of a carbon monoxide (CO) combustion promoter to the dilute phase transport riser, such that there is a greater concentration of said combustion promoter in the dilute phase transport riser than in the first dense bed and wherein after passing through said dilute phase transport riser combustion promoter is recycled to said dilute phase transport riser.