Removal of nitric oxide from exhaust gas with cyanuric acid

• Published in: Combustion and flame Vol. 79; no. 1; pp. 31 - 46
• Main Authors: Siebers, D.L., Caton, J.A.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 1990; Elsevier Science
• Subjects: 330102 - Internal Combustion Engines- Diesel; 330701 - Emission Control- Nitrogen Oxides; 400800 - Combustion, Pyrolysis, & High-Temperature Chemistry; 540120 - Environment, Atmospheric- Chemicals Monitoring & Transport- (1990-); ADVANCED PROPULSION SYSTEMS; AIR POLLUTION ABATEMENT; Air pollution caused by fuel industries; Applied sciences; Atmospheric pollution; AZINES; CARBON COMPOUNDS; CARBON MONOXIDE; CARBON OXIDES; CHALCOGENIDES; CHEMICAL REACTION KINETICS; CHEMICAL REACTORS; Combustion and energy production; COMBUSTION CHAMBERS; COMBUSTION PRODUCTS; CYANURATES; DATA; DIESEL ENGINES; DIESEL FUELS; ELEMENTS; Energy; Energy. Thermal use of fuels; ENGINES; ENVIRONMENTAL SCIENCES; Exact sciences and technology; EXHAUST GASES; EXPERIMENTAL DATA; FLUIDS; GASEOUS WASTES; GASES; HEAT ENGINES; HETEROCYCLIC COMPOUNDS; HYDROGEN COMPOUNDS; INFORMATION; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; INTERNAL COMBUSTION ENGINES; KINETICS; NITRIC OXIDE; NITROGEN COMPOUNDS; NITROGEN OXIDES; NONMETALS; NUMERICAL DATA; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; ORGANIC OXYGEN COMPOUNDS; OXIDES; OXYGEN; OXYGEN COMPOUNDS; PETROLEUM PRODUCTS; Pollution; POLLUTION ABATEMENT; Pollution reduction; Prevention and purification methods; REACTION KINETICS; REMOVAL; Stack gas and industrial effluent processing; TRIAZINES; WASTES; WATER; Simulation; Thermal decomposition; Nitrogen monoxide; Diesel engine; Air pollution; Combustion; Exhaust gas; Gas analysis; Isocyanic acid
• ISSN: 0010-2180; 1556-2921
• DOI: 10.1016/0010-2180(90)90086-7

Addition of gaseous isocyanic acid (HNCO) to the exhaust of combustion systems or chemical process has been proposed as a method for reducing nitric oxide (NO) emissions. The HNCO selectively reduces NO in the exhaust through a multistep chemical reaction mechanism. This article presents an experimental investigation of the proposed NO reduction process using cyanuric acid as the source of HNCO. At elevated temperature cyanuric acid decomposes and forms HNCO. The effects of temperature, exhaust gas composition, cyanuric acid concentration (i.e., HNCO concentration), and surfaces were examined. The experiments were conducted in an electrically heated quartz flow reactor using either exhaust from a diesel engine or simulated exhaust gas. The results demonstrate that gas phase NO reduction approaching 100% can be obtained. The lowest temperature for which gas phase NO reduction is observed is 950 K. The exhaust gas composition is the primary factor in determining the specific temperature range over which the NO reduction occurs, as well as the magnitude of the NO reduction, for a fixed cyanuric acid input. Three species in the exhaust gas that have a strong influence on the NO reduction process are O 2, H 2O, and CO. The results also demonstrate the cyanuric acid, HNCO, and N 2O can be emitted when the NO reduction occurs in the gas phase. Finally, the results show that surfaces can have a major effect, either shifting the NO reduction to lower temperatures or causing a net production of NO.