摘要:
A method for removing NOX from an oxygen-rich exhaust flow produced by a combustion source that is combusting a lean mixture of air and fuel may include passing the oxygen-rich exhaust flow through an exhaust aftertreatment system that includes a NOX oxidation catalyst that includes perovskite oxide particles, a NOX storage catalyst, and a NOX reduction catalyst.
摘要:
One embodiment of the invention may include a method comprising providing a product comprising a substrate comprising a perovskite catalyst, NOx stored in or on the substrate and particulate matter in or on the substrate; releasing at least some of the stored NOx and oxidizing the released NOx to form NO2, and reacting the NO2 with carbon in the particulate matter to form at least one of CO or CO2.
摘要:
One embodiment of the invention may include a product comprising a catalyst combination comprising a perovskite catalyst and a second catalyst that is not a perovskite catalyst.
摘要:
An after-treatment system architecture and method for oxidizing the nitric oxide component of a gas stream are disclosed. One embodiment may include treatment of a gas stream that includes NOx with a perovskite catalyst of the general formula ABO3 or a modified formula of ABO3 wherein a small amount of a promoter material is substituted for a portion of at least one of element A or element B in a catalytic oxidation reaction to oxidize nitric oxide in the gas stream.
摘要:
A bi-functional catalyst material, a SCR converter that includes the bi-functional catalyst material, an exhaust aftertreatment system that includes the SCR converter, and a method for removing NOX contained in an exhaust flow produced by a lean-burn engine are disclosed. The bi-functional catalyst material can (1) oxidize NO to NO2 and (2) selectively reduce NOX to N2 when exposed to an exhaust mixture that comprises the exhaust flow from the lean-burn engine and a suitable reductant. The bi-functional catalyst material comprises metal oxide particles selected from the group consisting of perovskite oxide particles and manganese-based mixed metal oxide particles dispersed on a selective catalytic reduction (SCR) catalyst.
摘要:
Following a cold start of a hydrocarbon-fueled engine operated in a lean-burn-combustion mode, several seconds and minutes may be required for the exhaust gas stream to heat exhaust treatment devices in the exhaust system and conduit to their effective operating temperatures. The warm-up period may be particularly long for a NOx reduction catalyst (SCR) located downstream in the exhaust flow system. Accordingly, a bed of absorbent material, such as a suitably sized bed of alumina particles, located upstream of the SCR, is used to temporarily absorb water and NOx from a relatively cold exhaust until the exhaust has suitably heated the SCR to its operating temperature. Then, the warmed exhaust will remove the water and NOx from their temporary storage material and carry them to the reduction catalyst.
摘要:
An exhaust aftertreatment system for a lean-burn engine may include a lean NOX trap that comprises a catalyst material. The catalyst material may remove NOX gases from the engine-out exhaust emitted from the lean-burn engine. The catalyst material may include a NOX oxidation catalyst that comprises a perovskite compound.
摘要:
One embodiment of the invention includes a method of treating a gas stream comprising flowing the gas stream over a hydrocarbon reduction and NOx reduction catalyst first, and thereafter flowing the gas over a perovskite and NOx trap material for NOx oxidation and storage. In one embodiment, the hydrocarbon reduction and NOx reduction catalyst may include palladium. In one embodiment, the perovskite catalyst may have the general formula ABO3, AA′BO3, ABB′O3, or AA′BB′O3. The perovskite catalyst may be the only catalyst or a second non-perovskite catalyst may include at least one of palladium, platinum, rhodium, ruthenium or a catalyst system including one or more of the same or alloys thereof. In one embodiment, the NOx trap material may include at least one of alkali metals, alkaline earth metals such as barium, calcium, potassium, or sodium.
摘要:
Particles of mixed oxides of cerium, zirconium, and copper (CeZrCuOX) may be prepared as catalysts and used to preferentially catalyze the oxidation of CO in exhaust streams containing CO and NH3. In one practice, this CeZrCuOX catalyst may be used in combination with a close-coupled PGM catalyst which promotes the formation of NH3 in the exhaust during fuel-rich operation, and at least one under-floor NH3-SCR catalyst, which catalyzes the reduction of NOX in the exhaust stream during fuel-lean operation using NH3 as a reductant. During fuel-rich engine operation, the exhaust stream may be doped with oxygen downstream of the PGM catalyst and passed in contact with particles of the CeZrCuOX catalyst so that residual CO in the exhaust may be oxidized to CO2, without oxidation or other conversion of the NH3.
摘要:
The oxidation of carbon monoxide (CO) and hydrocarbons (HC) in an oxygen-containing gas stream, such as the exhaust stream from a diesel engine, or other lean-burn engine, may be catalyzed using a combination of mixed oxide particles of cerium, zirconium and copper, and discrete particles of an alumina-supported platinum group metal catalyst. The catalyzed oxidation of CO and HC by this combination of oxidation catalyst particles is effective at temperatures below 300° C.