摘要:
A non-stoichiometric perovskite oxide having the general chemical formula LaXMnOY, in which the molar ratio of lanthanum to manganese (“X”) ranges from 0.85 to 0.95, can be used in particle form as an oxidation catalyst to oxidize NO to NO2 in an exhaust aftertreatment system for a hydrocarbon-fueled engine. The oxygen content (“Y”) fluctuates with variations in the molar ratio of lanthanum to manganese but generally falls somewhere in the range of 3.0 to 3.30. The crystal lattice adjustments spurred by the non-stoichiometric molar ratio of lanthanum to manganese are believed responsible for an enhanced NO oxidative activity relative to similar perovskite oxides with a higher molar ratio of lanthanum and manganese.
摘要:
A method of replacing or exchanging non-metal charge balancing cations located at ion-exchanges sites within SAPO frameworks with cations of a transition metal using a solid state ion-exchange process. Transition metal-containing particles are formed on surfaces of SAPO particles, and thereafter the particles are heated in air to initiate the solid-state ion-exchange process. The transition metal-containing particles and the SAPO particles are heated to a temperature and for an amount of time to produce transition metal cations, and for the transition metal cations to replace at least a portion of the non-metal cations located within the SAPO frameworks.
摘要:
An exhaust aftertreatment system that includes a suitable combination of particulate catalyst materials is used to effectively reduce an amount of NOX to N2 and water in a high-oxygen content exhaust flow from an engine that is controlled to operate by cyclically burning lean and rich mixtures of air and fuel. The catalyst materials of the exhaust aftertreatment system comprise (1) lanthanum-based perovskite oxide particles to oxidize NO to NO2, (2) barium oxide particles to temporarily store NO2, (3) copper oxide nanoparticles chemically deposited onto particles of cerium oxides to reduce NOX to N2 and to generate NH3, and (4) particles of a selective reduction catalyst to temporarily store NH3 and to reduce any residual NOX to N2 and water before the exhaust flow from the engine is discharged to the atmosphere.
摘要:
The oxidation of nitrogen oxide (NO) in an oxygen-containing exhaust gas flow from a diesel or other lean-burn engine may be catalyzed using particles of co-precipitated and calcined manganese (Mn), cerium (Ce) and zirconium (Zr) mixed oxides. In preferred embodiments, the molar ratios of Mn, Ce and Zr to the total amount of base metals in the ternary mixed oxide catalyst are in the range of 0.25-0.35, 0.40-0.50 and 0.20-0.25, respectively. Further, this ternary mixed oxide catalyst is less susceptible to sulfur poisoning than previously-disclosed binary mixed oxide catalysts. The ternary mixed oxide catalyst may also be regenerated—and the inhibiting effect of SO2 reversed—by briefly exposing the catalyst to a reducing exhaust gas environment.
摘要:
MnOx-containing, base-metal oxide mixtures (e.g., MnOx—CeO2) are useful NOx oxidation catalyst materials and NOx storage materials in lean-burn engine exhaust gas treatments using Lean NOx Trap (LNT) systems. These oxidation catalyst materials are used in combination with a NOx storage material and a NOx reduction material. MnOx-containing oxide mixtures can replace platinum (Pt) in LNT systems where the exhaust of the engine is repeatedly varied between a relatively long fuel-lean mode of operation and a relatively short fuel-rich mode of operation. The combination of the MnOx oxidation catalyst, NOx storage material, and NOx reduction catalyst material serves to complete the oxidation of unburned hydrocarbons and carbon monoxide, and to convert NOx to nitrogen.
摘要:
Engine exhaust gas feedstream NOx emissions aftertreatment includes a catalytic device connected upstream of an ammonia-selective catalytic reduction device including a base metal. Engine operation can be modulated to generate an engine-out exhaust gas feedstream that converts to ammonia on the catalytic device. The ammonia is stored on the ammonia-selective catalytic reduction device, and used to reduce NOx emissions in the exhaust gas feedstream.
摘要:
An exhaust aftertreatment system that includes a suitable combination of particulate catalyst materials is used to effectively reduce an amount of NOX to N2 and water in a high-oxygen content exhaust flow from an engine that is controlled to operate by cyclically burning lean and rich mixtures of air and fuel. The catalyst materials of the exhaust aftertreatment system comprise (1) lanthanum-based perovskite oxide particles to oxidize NO to NO2, (2) barium oxide particles to temporarily store NO2, (3) copper oxide nanoparticles chemically deposited onto particles of cerium oxides to reduce NOX to N2 and to generate NH3, and (4) particles of a selective reduction catalyst to temporarily store NH3 and to reduce any residual NOX to N2 and water before the exhaust flow from the engine is discharged to the atmosphere.
摘要:
Engine exhaust gas feedstream NOx emissions aftertreatment includes a catalytic device connected upstream of an ammonia-selective catalytic reduction device including a base metal. Engine operation can be modulated to generate an engine-out exhaust gas feedstream that converts to ammonia on the catalytic device. The ammonia is stored on the ammonia-selective catalytic reduction device, and used to reduce NOx emissions in the exhaust gas feedstream.
摘要:
A high-surface area fine particle dispersal of LaMnO3 or a promoted derivation of LaMnO3 may be prepared by the citrate method. The amount of citric acid used to complex the constituent metal cations into citrate complexed mixed metal compounds may range from about 40 mol % to about 100 mol % in excess of stoichiometry.
摘要:
Chemical species such as nitrogen oxide (NO), carbon monoxide, and low molecular weight hydrocarbons (e.g., C1-C5 and saturated or ethylenically unsaturated) in an oxygen-containing gas stream, such as the exhaust stream from a diesel engine, or other lean burn engine, may be oxidized using a mixture of MnOx with one or more other base metal oxides, with or without palladium. The oxidation is effective at temperatures above about 200° C. to convert about ninety percent or more of the carbon monoxide to carbon dioxide and to consume the hydrocarbons. The oxidation is also effective to convert much of the NO to NO2. In general, the mixed base metal oxides may be used as catalysts for the oxidation of nitrogen oxide in hot gas streams containing oxygen. They may optionally be used in a combination with palladium or platinum. But platinum, which is very expensive, does not have to be used in such oxidation reactions.