In an exhaust system for a motor vehicle having an exhaust treatment device for after-treating exhaust gas of a combustion engine of the motor vehicle, the exhaust gas treatment device includes a first SCR catalyst, which has a zeolite material containing copper, an ammonia slip catalyst, which is arranged downstream of the first SCR catalyst, and a particulate filter. A second SCR catalyst, which has an SCR catalyst material containing vanadium, is arranged upstream of the first SCR catalyst.

A co-catalyst system for the removal of NO.sub.x from an exhaust gas stream has a layered oxide and a spinel of formula Ni.sub.0.15Co.sub.0.85CoAlO.sub.4. The system converts to nitric oxide to nitrogen gas with high product specificity. The layered oxide is configured to convert NO.sub.x in the exhaust gas stream to an N.sub.2O intermediate, and the spinel is configured to convert the N.sub.2O intermediate to N.sub.2.

A compact SCR device is provided for use with a diesel exhaust fluid (DEF) injection system having multiple injectors for providing diesel exhaust fluid to exhaust gas to reduce NO.sub.x emissions. The DEF injectors are disposed in the close coupled SCR mixer. A first injector injects into a chamber of the mixer with sidewardly oriented impingement plates having openings. A second injector radially spaced and offset has a different angle from the first injector for injecting DEF into the SCR mixer. A swirl plate forces the exhaust gas in the flow path to turn and exit through an outlet opening. An inlet opening for the mixer is aligned transversely near the first injector and is offset from the outlet opening. Thus, upon entering the compact SCR mixer, the exhaust gas must change direction and passes by at least one injector and impingement plates having flaps and openings before exiting the mixer.

In an exhaust system for a motor vehicle having an exhaust treatment device for after-treating exhaust gas of a combustion engine of the motor vehicle, the exhaust gas treatment device includes a first SCR catalyst, which has a zeolite material containing copper, an ammonia slip catalyst, which is arranged downstream of the first SCR catalyst, and a particulate filter. A second SCR catalyst, which has an SCR catalyst material containing vanadium, is arranged upstream of the first SCR catalyst.

In order to provide an exhaust gas purification catalyst capable of purifying hydrocarbons, carbon monoxide, and nitrogen oxides in exhaust gas at low temperatures, the exhaust gas purification catalyst according to the present invention includes: a region (2) containing palladium and yttrium on a three-dimensional structure (1), and a first region (3) and a second region (4) provided on the region (2) in order from an inflow side of exhaust gas to an outflow side of exhaust gas. The concentration of yttrium contained in the first region (3) and/or the second region (4) is higher than the concentration of yttrium contained in the region (2).

In order to provide an exhaust gas purification catalyst capable of purifying hydrocarbons, carbon monoxide, and nitrogen oxides in exhaust gas at low temperatures, the exhaust gas purification catalyst according to the present invention includes: a region (2) containing palladium on a three-dimensional structure (1), and a first region (3) and a second region (4) provided on the region (2) in order from an inflow side of exhaust gas to an outflow side of exhaust gas. The concentration of neodymium contained in the first region (3) is higher than the concentration of neodymium contained in the second region (4).

A NO.sub.x absorber catalyst for treating an exhaust gas from a diesel engine. The NO.sub.x absorber catalyst comprises a first NO.sub.x absorber material comprising a molecular sieve catalyst, wherein the molecular sieve catalyst comprises a noble metal and a molecular sieve, and wherein the molecular sieve contains the noble metal; a second NO.sub.x absorber material comprising palladium (Pd) supported on an oxide of cerium; and a substrate having an inlet end and an outlet end.

A honeycomb structure includes a pillar-shaped honeycomb structure body which has porous partition walls disposed to surround a plurality of cells Among the partition walls surrounding one of the cells, each of the partition walls constituting two opposite sides of the cell sandwiched therebetween is provided with a projection which project to extend into the cell and which is continuously provided in a direction in which the cell extends, and the area S1 of one region of the cell divided by a virtual line that virtually connects distal ends of the two projections in a section of the honeycomb structure body, and the area S2 of the other region (S1S2) of the cell satisfy 70%S1/S2100%.

A co-catalyst system for the removal of NO.sub.x from an exhaust gas stream has a layered oxide and a spinel of formula Ni.sub.0.15Co.sub.0.85CoAlO.sub.4. The system converts to nitric oxide to nitrogen gas with high product specificity. The layered oxide is configured to convert NO.sub.x in the exhaust gas stream to an N.sub.2O intermediate, and the spinel is configured to convert the N.sub.2O intermediate to N.sub.2.

Described are exhaust gas treatment systems for treatment of a gasoline engine exhaust gas stream containing NOx, particulate matter, and sulfur. The exhaust gas treatment system comprises: one or more catalytic articles selected from a three-way conversion catalyst (TWC), a lean NOx trap (LNT), and an integrated LNT-TWC; a platinum-containing catalytic article downstream from the one or more catalytic articles; and one or more selective catalytic reduction (SCR) catalytic articles immediately downstream from the platinum-containing catalytic article, the one or more SCR catalytic articles including a molecular sieve. The system stabilizes the SCR catalytic article from poisoning by sulfur.