An FCC regenerator comprising a first dense bed coke combuster, a dilute phase transport riser, and a second dense bed operates with selective addition of CO combustion catalyst downstream of the coke combustor and preferably into the dilute phase transport riser. The process and apparatus permits maintenance...http://www.google.es/patents/US4812430?utm_source=gb-gplus-sharePatente US4812430 - NO.sub.x control during multistage combustion
