Abstract: The disclosure relates to an absorbent for removing acid gases from fluids. The absorbent contains at least one tertiary amine, an amine which is selected from hydroxyethylpiperazine, bis(hydroxyethylpiperazine) or a mixture of these and piperazine. The absorbent may optionally contain a physical solvent for the acid gases.

Abstract: A non-catalytic process for reducing nitrogen oxide (NOx) emissions in the combustion effluent of a stationary combustion apparatus is provided comprising contacting, in the combustion zone of the combustion apparatus, an effective amount of at least one nitrile compound with a waste stream, an auxiliary fuel stream, and air at a temperature sufficient to reduce the NOx emissions in the combustion effluent.

Abstract: A method for removing ammonia from a gas comprising HCN, ammonia and water, by first contacting the gas with aqueous ammonium phosphate to remove ammonia from the gas, and then passing the resulting ammonium phosphate solution through an electrolyzer to convert oxalates and formates into hydrogen and carbon dioxide.

Abstract: The invention concerns the use of a composition based on TiO2 as a catalyst for hydrolyzing COS and/or HCN in a gas mixture; said composition comprising at least 1% by weight of at least one sulphate of an alkaline-earth metal selected from calcium, barium, strontium and magnesium.

Abstract: A method for removing ammonia from a gas comprising HCN, ammonia and water, by first contacting the gas with aqueous ammonium phosphate to remove ammonia from the gas, and then passing the resulting ammonium phosphate solution through an clectrolyzer to convert oxalates and formates into hydrogen and carbon dioxide.

Abstract: The present invention relates generally to the use of a combination of alkali metal hydroxides and alkaline-earth metal hydroxides as a scavenging material for cyanide gas. In particular, the present invention relates to a method and means for either filtering out cyanide gas or detoxifying areas contaminated with cyanide using Sodalime or Baralyme™. The scavenging material of the invention is typically incorporated into a scrubbing device wherein a motor (50) powers a fan (52) to draw contaminated air into an inlet (54) and across a filter (56) which contains the scavenger material, thereby absorbing cyanide gas contained in the air.

Abstract: A process is provided for the catalytic removal of polycyclic aromatic nitro, nitroso and/or amino compounds from the exhaust gas of a combustion system, in particular a diesel engine. The exhaust gas is brought into contact with a catalytic converter which includes a catalytically active material that contains titanium dioxide, at a temperature of from 150 to 600° C. The polycyclic aromatic compounds are oxidized at the catalytic converter through the use of oxygen to form nitrogen oxides, carbon dioxide and water.

Abstract: Disclosed is a process for the treatment of a plant fluid effluent containing odor compounds including an alkyl mercaptan or an alkyl thiol, an amine compound, ammonia, hydrogen sulfide and mixtures thereof by contacting the plant effluent in either a counterflow or cocurrent flow process. In the process, the effluent is contacted with an aqueous solution comprising a peroxyacid compound and one or more essential oils. When contacted with the peroxyacid, odor compounds in the effluent are oxidized and converted from the gaseous phase into a chemically modified highly aqueous soluble phase in the aqueous treatment. In this way, odor removal from the gas is preferred and odor compounds are efficiently transferred into the aqueous treatment solution. The use of such a process produces a significant improvement in odor quality index as measured by a conventional process using an expert panel when compared to conventional treatment methods.

Abstract: The present invention relates to the use of an absorption liquid for purifying a gas by removal of gaseous, acidic impurities. The gas to be purified can be any gas, such as synthesis gas or natural gas, which contains gaseous, acidic impurities such as CO2, H2S, SO2, CS2, HCN, COS or mercaptans. The absorption liquid comprises: A) from 0.01 to 4% by weight of at least one compound of the formula B) from 0.001 to 8.0% by weight of water, and C) at least one polyalkylene glycol alkyl ether of the formula R1—O—(R2—O)x—R3 to 100% by weight, where R1 is C1-C4-alkyl, R2 is ethylene or 2-methylethylene, R3 is hydrogen or C1-C4-alkyl, R4 is hydrogen or C1-C4-alkyl, R5 is C1-C4-alkylene and X is an integer from 1 to 10. The amine may be N-methyldiethanolamine and the ether may be polyethylene glycol dimethyl ether.

Abstract: Carbonyl sulfide and/or hydrogen cyanide contained in a mixed gas are/is converted by contacting the mixed gas with an alkalized chromium oxide-aluminum oxide catalyst in the presence of steam, wherein the mixed gas and the steam at a volume ratio of 0.05≦steam/mixed gas≦0.3 are contacted with the alkalized chromium oxide-aluminum oxide catalyst at a gas hourly space velocity no less than 2000 h−1 at a temperature in the range of 150° C. through 250° C. In this case, the alkalized chromium oxide-aluminum oxide catalyst is set to have a grain size in the range of 1 mm through 4.5 mm. With this arrangement, since the surface area of a catalyst can be increased to a certain degree, the activity of the catalyst is increased to achieve the high processing speed, while since generation of a side reaction can be suppressed, lowering of the conversion rate of COS and/or HCN caused by the side reaction can be suppressed.

Abstract: A method of removing mercury from a mercury-containing flue gas, especially flue gas from a refuse incinerator, is provided. The mercury-containing flue gas may also contain dust, further heavy metals, and further gaseous noxious gas components. The mercury, using an alkali sulfide solution, especially sodium sulfide solution, and in particular sodium tetrasulfide solution, is converted to mercury sulfide and the mercury sulfide is precipitated out via a dust separator. The alkali sulfide solution is introduced into the flue gas accompanied by the simultaneous addition of heat.

Abstract: A method of recovering AlF3 from spent potliner using an acid digest to form gaseous HF which is converted to hydrofluoric acid and reacted with alumina trihydrate to form AlF3.

Abstract: A process of treating spent potliner material from aluminum reduction cells and recovering useful products. In the process of the present invention, spent potliner material is introduced into an acid digester containing, for example, sulfuric acid. As a result of this step, a gas component is produced which includes hydrogen fluoride, silicon tetrafluoride and hydrogen cyanide. Also, a slurry component is produced which includes carbon, a refractory material including silica, alumina, sodium compounds such as sodium sulfate, aluminum compounds such as aluminum sulfate, iron compounds such as iron sulfate, magnesium and calcium compounds such as magnesium and calcium sulfate. The slurry component remains in the digester after the gas component is removed. The gas component is recovered and heated an effective amount to convert or decompose the silicon tetrafluoride to fumed silica, hydrogen cyanide to a remaining gas component including CO.sub.2, H.sub.2 O, and nitrogen oxides, as well as HF gas.

Abstract: The invention relates to a method of imparting anti-pathogenic properties to a substrate material comprising: (a) preparing a coating composition containing an anti-pathogenic agent consisting essentially of PVP-I and N-9 in a ratio of from about 100:0 to about 0:100 of PVP-I to N-9, the coating composition further containing a pre-mix solution with which the anti-pathogenic agent is intimately mixed in a ratio of from about 6:4 to about 8:2 of agent to pre-mix on a dry basis, and having a percent solids content of from about 5% to about 35% solids; (b) feeding the anti-pathogenic coating composition into a coating machine; (c) loading substrate onto the coating machine; (d) operating the coating machine such that the coating composition comes into intimate contact with at least one surface of the substrate; and (e) drying the coated substrate material.

Abstract: A supported metal oxide catalyst for the decomposition of ammonia and hydrogen cyanide in coke-oven gas is free of noble metals and comprises, based on the total catalyst, from 2 to 5.5% by weight of NiO and from 0.5 to 3.5% by weight of CoO on an MgO support. This catalyst is used in a process for the single-stage catalytic decomposition of ammonia and hydrogen cyanide in coke-oven gas before the latter is fed to a Claus desulfurization plant.

Abstract: Cyanide and ammonia are removed from a gas, such as a synthesis gas, by catalytically hydrolyzing cyanide in the gas to ammonia, water scrubbing the hydrolyzed gas to dissolve ammonia and at least a portion of remaining cyanide, and optionally, contacting the scrubbed gas with an adsorbent for cyanide and ammonia to form a clean gas containing less than 50 vppb of a combined total of cyanide and ammonia. The clean synthesis gas is then fed into a hydrocarbon synthesis reactor wherein it produces hydrocarbons with substantially reduced catalyst deactivation and cleaner hydrocarbon products.

Abstract: A method and apparatus for removing TDI from a gas in which the gas containing the TDI is forced through a scrubber tank. A first water spray is in fluid communication with the gas flowing through an inlet pipe and initially reacts the TDI in the gas with water. The gas is directed against a water surface at the bottom of the tank and thereafter, flows up an interior side wall of the tank. Deflectors mounted on the side wall disrupt the laminar flow of the gas and redirect it in a turbulent manner through a second water spray prior to the gas exiting the scrubber tank.

Abstract: The HCN concentration of HCN containing synthesis gas streams is reduced by treatment with a Group IVA metal oxide and optionally containing a Group IIB, Group VA, or Group VIA metal or metals, at reaction conditions preferably suppressing Fischer-Tropsch activity.

Abstract: A method improves the operation of a diesel engine through the use of a fuel additive, a diesel particulate trap and a NO.sub.x -reducing catalyst. The operation of the NO.sub.x -reducing catalyst is enhanced by the introduction of urea or like compound upstream of the catalyst at temperatures effective for non-catalytic NO.sub.x reduction and the generation of ammonia. The additive comprises fuel-soluble compositions of platinum group metal in effective amounts to lower the emissions of unburned hydrocarbons and carbon monoxide from the trap. The catalytic activity provided to the exhaust system by the fuel additive is selective and preferably reduces the oxidation of SO.sub.2 to SO.sub.3. The platinum group metal compositions are preferably added in amounts effective to provide concentrations of the metal in the fuel of less than 1 part per million (ppm). Lithium and/or sodium compositions can be used in amounts effective to reduce the trap regeneration temperature, e.g.

Abstract: A method for adsorbing and oxidizing VOC's in the same bed, thus reducing the size of or even eliminating the need for a catalytic or thermal oxidation unit at the end of the system. In this system, a catalyst is intimately interspersed with the adsorbent material. The catalyst oxidizes VOC's released during desorption when it reaches the `light off temperature,` that is, the catalyst temperature necessary for oxidation to begin. As VOC's are desorbed, they are combusted by the catalyst in the same bed and also by their combustion, heat the bed to aid in the desorption of VOC's elsewhere in the bed.

Abstract: A catalyst based on titanium oxide, zirconium oxide or combinations thereof for decomposing HCN in gases, which additionally comprises:molybdenum, vanadium, tungsten, manganese, silicon, selenium, tellurium, niobium, tantalum, sulfur, phosphorus in the form of their oxides, hydrated oxides, other compounds, or combinations thereof.

Abstract: Hydrogen cyanide is removed from an HCN containing gas, e.g., a gas containing CO+H.sub.2, by contact with a metal oxide catalyst comprised of the oxides of molybdenum, titanium, and aluminum in the presence of water vapor, and subsequently water washing the resulting gas.

Abstract: A process for treating spent potliner material from aluminum reduction cells and recovering useful products. In the process, spent potliner material is introduced into an acid digester containing, for example, sulfuric acid. A gas component is produced which includes hydrogen fluoride and hydrogen cyanide. A slurry component is produced which includes carbon, silica, alumina, sodium compounds such as sodium sulfate, aluminum compounds such as aluminum sulfate, iron compounds such as iron sulfate, magnesium and calcium compounds such as magnesium and calcium sulfate. The slurry component remains in the digester after the gas component is removed. The gas component is recovered and heated an effective amount to convert or decompose the hydrogen cyanide to a remaining gas component including CO.sub.2, H.sub.2 O, and nitrogen oxides, as well as HF gas. The remaining gas component is directed through a water scrubber in which the HF gas is converted to liquid hydrofluoric acid.

Abstract: A process for producing and cleaning a synthesis gas which contains ammonia and hydrogen cyanide catalytically converts most of the cyanide to ammonia which, along with some of the cyanide, is removed from the gas with water to form aqueous solutions of ammonia and cyanide. The hydrocarbon gas feed to the synthesis gas generator is used to strip ammonia and cyanide out of one or more of the aqueous solutions of these two species formed during the process and pass them into the generator in which they are consumed to form clean water. A portion of the resulting clean water is recycled back into the process where it used to scrub the synthesis gas, with the remainder used for other purposes or sent to disposal.

Abstract: A gas conversion process includes producing a synthesis gas which contains ammonia and hydrogen cyanide and forms hydrocarbons by reacting the hydrogen and carbon monoxide in the gas in the presence of a hydrocarbon synthesis catalyst also reversibly deactivates the catalyst due to the presence of the ammonia and hydrogen cyanide in the gas. The catalyst is rejuvenated with a gas comprising hydrogen and produces an ammonia containing rejuvenation offgas. The ammonia is dissolved out of the offgas with water and then stripped out of the water with the hydrocarbon feed to the synthesis gas generator and into the generator where it is consumed.

Abstract: Food grade carbon dioxide is produced from oxyfuel fired glassmaking furnace waste gas by a series of steps including quenching the waste gas with aqueous quench liquid, dry-filtering sulfur salt from the gas, scrubbing the filtered gas with aqueous carbonate to convert the remaining sulfur dioxide to an aqueous sulfite suspension and using the suspension as part or all of the above-mentioned aqueous quench liquid, contacting the sulfur dioxide-free waste gas with ammonia in the presence of a catalyst that selectively converts nitrogen oxides to nitrogen, thereby removing substantially all nitrogen oxides from the waste gas, and distilling the resulting waste gas stream thereby producing high purity liquid carbon dioxide and producing an off-gas, which is recycled to the furnace as fuel.

Abstract: A method of treating a gaseous stream containing one or more volatile nitrogen containing organic compounds which comprises contacting the gaseous stream and an oxidizing agent with a catalyst at relatively low temperatures to cause oxidation of the volatile nitrogen-containing organic compounds. The catalyst employed promotes the oxidation reaction to selectively produce N.sub.2 O, N.sub.2, CO.sub.2 and H.sub.2 O without generating significant amounts of NO.sub.x to permit the reaction products to be vented directly into the atmosphere. The catalyst includes a selected amount of a noble or base metal deposited on a catalyst support comprising titania and zirconia. One or more of the elements molybdenum, tungsten or vanadium are added as promoters to the composition which minimizes the generation of NO.sub.x among the reaction products. Lanthanum may be added to provide better thermal stability and increase the selectivity for producing N.sub.2 among the reaction products.

Abstract: Hydrogen cyanide or ammonia present in a gaseous stream is decomposed catalytically in the presence of oxygen at relatively low temperature by contact with carbonaceous adsorbents doped with oxides of first row transition metals, silver or lanthanide elements, preferably with cobalt, chromium, manganese, silver, and cerium, in the presence or absence of a gaseous reducing agent such as a hydrocarbon or a volatile carboxylic acid.

Abstract: A powerful reducing agent such as hydrazine monohydrate is added to the standard eluent solutions such as NsOH-NaCN with or without alcohol. The kinetics of elution of gold or of silver are thus markedly enhanced.

Abstract: Nitrogen oxides are removed from an exhaust gas containing nitrogen oxides and oxygen in an amount larger than its stoichiometric amount relative to unburned components in the exhaust gas, by using an exhaust gas cleaner having Ag supported by a porous inorganic oxide body and second catalyst containing second catalytically active components supported by a porous inorganic oxide body. The second catalytically active components consist essentially of Cu and/or other metals such as alkali metal elements, rare earth elements, etc.

Abstract: A method of cleaning an exhaust gas using an exhaust gas cleaner constituted by a first catalyst comprising a first porous inorganic oxide supporting an Ag component, a W component and a Pt component and optionally a second catalyst comprising a second porous inorganic oxide supporting a Pt component alone or in combination with a W component. The Ag component may include Ag and compounds thereof, the Pt component of the first and second catalysts may include Pt, Pd, Ru, Rh, Ir and Au, and the W component of the first and second catalysts may include W, V, Mn, Mo, Nb and Ta. The W component effectively catalyze the reduction of nitrogen oxides by ammonia to enhance the removal efficiency of the exhaust gas cleaner.

Abstract: The invention is a method for reducing the hydrogen cyanide and ammonia content of a synthesis gas stream exiting a gasifier including mixing an iron-containing compound with a nitrogen-containing coal feed; gasifying the coal feed in the resulting mixture in an entrained flow gasifier have opposed burners under gasifying conditions thereby producing a gas comprising hydrogen and carbon monoxide; and recovering the gas stream having substantially reduced amounts of hydrogen cyanide.

Abstract: A method of treating a gaseous stream containing one or more volatile nitrogen-containing organic compounds which comprises contacting the gaseous stream and an oxidizing agent with a catalyst at relatively low temperatures to cause oxidation of the volatile nitrogen-containing organic compounds. The catalyst employed promotes the oxidation reaction to selectively produce N.sub.2 O, N.sub.2, CO.sub.2 and H.sub.2 O without generating significant amounts of NO.sub.x to permit the reaction products to be vented directly into the atmosphere. The catalyst includes a selected amount of a noble or base metal deposited on a catalyst support comprising titania or zirconia. One or more of the elements molybdenum, tungsten or vanadium are added as promoters to the composition which minimizes the generation of NO.sub.x among the reaction products. Lanthanum may be added to provide better thermal stability and increase the selectivity for producing N.sub.2 among the reaction products.

Abstract: There is disclosed a process for cleaning a harmful gas which comprises bringing a gas containing a basic gas as a harmful component such as ammonia and amines into contact with a cleaning agent comprising a cupric salt supported on an inorganic carrier composed of an metallic oxide such as silica and alumina or a metallic oxide mixture of cupric oxide and manganese dioxide to remove the harmful component from the gas containing a basic gas.According to the above process, it is made possible to effectively remove a basic gas such as ammonia and trimethylamine contained in the exhaust gas from semiconductor production process; and a harmful basic gas contained in dilution gas such as air or nitrogen which dilutes the harmful gas suddenly leaked in emergency from a gas bomb filled inside with the harmful gas. Moreover, the process enables to prevent the occurrence of fire even in the coexistence of other gas such as silane, while maintaining excellent effect on the removal of the harmful gas.

Abstract: The invention relates to a process for the removal of HCN from gas mixtures that contain at least HCN and sulfur compounds, especially from gas mixtures that are obtained by partial oxidation of hydrocarbons, by catalytic decomposition of HCN, as well as a catalyst for the decomposition of HCN. According to the invention, the gas mixture is brought into contact with a catalyst which decomposes the HCN by hydrogenation and/or by hydrolysis and COS that is contained in the gas mixture is decomposed at least partially in this catalyst by hydrolysis. Advantageously, a catalyst that is based on titanium oxide and/or zirconium oxide as a vehicle and that contains chromium oxide as an active component is used. Advantageously, the catalyst is reduced during catalyst production or before use with H.sub.2 and/or a reducing gas at temperatures above the operating temperature of catalytic decomposition.

Abstract: A reactive membrane for removing impurities, such as water, oxygen and organic compounds, from a gas is provided. The reactive membrane includes a porous inorganic substrate having exposed surfaces and at least one carbon layer, which is modified to present active sites, deposited on the exposed surfaces. The active sites include metal species which are at least partially deoxygenated and are chemically bonded to the carbon layer. Methods of forming the reactive membrane and of removing impurities from a gas with the membrane are also provided.

Abstract: A process for purifying an exhaust gas comprising carbon monoxide, hydrocarbons, nitrogen oxides, and sulfur oxides by periodically adjusting exhaust gas conditions from lean-burn to fuel-rich and by using a catalyst comprising an alumina support with lithium dissolved therein to form a solid solution, at least one first ingredient selected from the group consisting of platinum and palladium loaded on the alumina support, and at least one second ingredient selected from the group consisting of alkali elements, alkaline-earth elements, and rare-earth elements loaded on the support. Sulfates formed from sulfur oxides in the exhaust gas are decomposed by the lithium under the fuel-rich conditions to inhibit the alumina support from being acidified.

Abstract: Alkyl nitrite-containing exhaust gases are purified in continuous form by treating them with equimolar to excess amidosulphuric acid in the form of an aqueous solution in the manner of a counter-current scrubbing at a temperature of 0.degree.-100.degree. C.

Abstract: A dual-impregnated activated carbon composition includes activated carbon impregnated with a Group 6-12 metal salt and a Group 1 metal carbonate salt, where the molar ratio on the activated carbon of the Group 1 metal to the Group 6-12 metal is 1 or greater. The dual-impregnated activated carbon composition is particularly suitable for filtering gaseous contaminants.

Abstract: This invention relates to novel cobalt and molybdenum promoted titania and nickel and molybdenum promoted titania catalysts, and molybdenum promoted titania catalysts containing mixtures of cobalt and nickel. The invention also relates to a process for using the catalysts to convert sulfur in the form of carbon sulfides and nitrogen present as hydrogen cyanide to hydrogen sulfide and ammonia respectively. The catalysts and process of the present invention are effective even when oxygen in concentrations up to about 2 volume %, preferably 1.0 volume %, (dry basis) is present. The catalyst comprises about 0.5 to about 5%, by weight, cobalt oxide (CoO), nickel oxide (NiO), or mixtures thereof; about 1.5 to about 15%, by weight, molybdenum trioxide (MoO.sub.3); and about 70 to about 98%, by weight, titanium dioxide (TiO.sub.2).

Abstract: Process for preparing isocyanic acid by bringing cyanuric acid into contact with an aluminum catalyst at temperatures of from 300.degree. to 600.degree. C. and isolating the isocyanic acid formed or directly using it for further reaction.

Abstract: A process is described wherein the HCN in FCC hydrocarbon gas streams is converted to NH.sub.3 over a catalyst. This conversion has the desirable result of decreasing the amount of CN.sup.- in the water leaving the sour-water stripper, and ultimately in the refinery water effluent.

Abstract: A method for reducing cyanide contaminants in refinery waste waters prior to reuse or release into the environment comprising adding to the waters a cyanide reactive scavenger comprising at least one amine-aldehyde reaction product.

Abstract: Novel polyarylamide derived activated carbon materials are provided by a process comprising the carbonization of polyarylamide fibre at a temperature in excess or 400.degree. C. followed by activation at elevated temperature. The novel materials have the ability to adsorb relatively large quantities or carbon dioxide compared to other activated carbonized polymer materials, Preferably the carbonization and activation steps are carried out by raising the temperature of the materials to between 840.degree. C. and 880.degree. C. in carbonizing/activating atmospheres respectively.

Abstract: Oxides of nitrogen (NO.sub.x) emissions from an FCC regenerator are reduced by operating the regenerator in partial CO burn mode and adding substoichiometric, or just stoichiometric air to the flue gas. Much CO and most NO.sub.x and NO.sub.x precursors are thermally converted at 2000.degree.-2900.degree. F., then the gas is cooled below about 1800.degree. F. and burning of CO completed.

Abstract: Process for recovering cyanide values from a mill tailings stream remaining after gold and silver have been leached from an ore, by treating the tailings stream containing both ore insolubles and remaining cyanide leachant, without a preliminary filtration, to acidification with an acid to a pH of at least 4, stripping the cyanide values therefrom with a stripping gas in a stripping column such as a baffle plate column wherein the average residence time of the column is sufficiently low that the pH of the stream does not rise above about 4 and the ore insolubles do not plug the column, introducing the stripping gas and stripped cyanide values into an absorbing column containing an alkaline liquor to absorb the cyanide values, recovering the absorbed cyanide values, and removing a stripped tailings stream reduced in cyanide values.

Abstract: Composition, method and apparatus for providing a surface stabilized source of HNCO by adsorbing gaseous or liquid HNCO on the surface of a substrate. HNCO stabilized in this manner is not reactive and is stable at or above ambient temperature. The HNCO can be provided by heating a reactant source material, such as urea. The substrate can be heated to release HNCO. The present invention is especially useful as a source of HNCO for reducing NO.sub.x in gas streams.

Abstract: A refinery catalyst is regenerated by burning off coke in an air stream to give an off-gas: before cryogenic recovery of hydrocarbons from the off-gas, nitrogen oxides (NOx) are removed from the off-gas by contact with a hydrogenation catalyst.

Abstract: The present invention relates to a process for generating reactive species for destroying toxic chemicals. This process first contacts air or oxygen with aqueous emulsions of molten yellow phosphorus. This contact results in rapid production of abundant reactive species such as O, O.sub.3, PO, PO.sub.2, etc. A gaseous or liquid aqueous solution organic or inorganic chemicals is next contacted by these reactive species to reduce the concentration of toxic chemical and result in a non-toxic product. The final oxidation product of yellow phosphorus is phosphoric acid of a quality which can be recovered for commercial use. A process is developed such that the byproduct, phosphoric acid, is obtained without contamination of toxic species in liquids treated. A gas stream containing ozone without contamination of phosphorus containing species is also obtained in a simple and cost-effective manner.

Abstract: A method is disclosed for the addition of an oxygen-containing gas under certain defined process conditions, to an off-gas stream derived from an FCC regenerator which is operated in a partial mode of combustion. The off-gas from the regenerator contains 1-6% CO by volume and at least 300 ppm nitrogen compounds comprising NH.sub.3 and HCN. Without the addition of an oxygen-containing gas, roughly 25 percent of the NH.sub.3 and HCN are converted to NO.sub.x in downstream CO boilers. A preferable method of this invention comprises the addition of heated air (20% O.sub.2) into the regenerator off gas to produce an off gas stream having a temperature of 1260.degree. F. to 1500.degree. F.