Simultaneous sulfur oxide and nitrogen oxide control in FCC units using cracking catalyst fines with ammonia injection

Claim 1

A process for lowering the amount of nitrogen oxides in a flue gas from a regenerator of a fluid catalytic cracking unit in which the circulating inventory of the unit contains at least a particulate cracking catalyst containing at least 20% alumina, a sulfur oxide sorbent, and a sulfur dioxide oxidation promoter, including the steps of: (a) lowering the temperature of the flue gas to at least about 850° F.; (b) mixing sufficient ammonia or an ammonia generating compound with the flue gas to achieve the desired reduction of said nitrogen oxide; (c) passing the flue gas in the presence of oxygen through means for collecting and supporting cracking catalyst fines entrained in the flue gas; and (d) controlling the temperature of the flue gas as it passes through said collecting and supporting means to between about 350° F. and about 850° F., whereby the nitrogen oxide in flue gas is reduced as it contacts the supported catalyst in the collecting and supporting means.