NOx control in fluidized bed combustion

Claim 1

In a fluidized catalytic cracking (FCC) process wherein conventional FCC catalyst contacts conventional FCC feedstock in a conventional FCC reactor to produce cracked products and coked catalyst which is regenerated in a conventional FCC regenerator comprising a single dense bed to which air or an oxygen-containing gas is added to produce a regenerated catalyst and flue gas containing CO 2 and NO x resulting from coke combustion, and wherein carbon monoxide (CO) combustion promoter is uniformly distributed in the catalyst bed to promote complete combustion of CO to CO 2 , the improvement comprising maintaining a majority of the CO combustion promoter as a solid particle with a volume at least 10 times greater than the conventional FCC catalyst and having a low density, relative to the dense bed density, so that the promoter floats to the top of the regenerator dense bed of FCC catalyst in the FCC regenerator, and maintaining a reducing atmosphere in a lower one-half portion of the dense bed of FCC catalyst in the FCC regenerator and converting in the reducing atmosphere at least a portion of the NO x formed during coke combustion to nitrogen.