摘要 |
Reduced emissions of gas phase reduced nitrogen species in the off gas of an FCC regenerator operated in a partial or incomplete mode of combustion is achieved by contacting the off gas with an oxidative catalyst/additive composition having the ability to reduce gas phase nitrogen species to molecular nitrogen and to oxidize CO under catalytic cracking conditions. The oxidative catalyst/additive composition is used in an amount less than the amount necessary to prevent afterburn. Fluidizable particles of the oxidative catalyst/additives are circulated throughout the partial or incomplete burn FCC unit along with the FCC catalyst inventory. The flue gas having a reduced content of gas phase reduced nitrogen species and NOx is passed to a downstream CO boiler, preferably a low NOx CO boiler. In the CO boiler, as CO is oxidized to CO2, a reduced amount of gas phase reduced nitrogen species is oxidized to NOx, thereby providing an increase in the overall reduction of NOx emitted into the environment.
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