An emissions treatment system for an exhaust stream of a diesel engine or a lean burn gasoline engine comprising:nan in-situ ammonia-generating component, wherein the ammonia-generating component comprises a lean NOx trap (LNT) catalytic material disposed on an upstream carrier that is a flow through monolith, wherein the lean NOx trap (LNT) catalytic material comprises an undercoat washcoat layer and a top washcoat layer, the top washcoat layer exhibiting better low temperature NOx abatement performance than the undercoat washcoat layer; andan SCR catalyst disposed downstream of the ammonia-generating component, wherein the SCR catalyst comprises a molecular sieve having the CHA crystal structure, wherein the SCR catalyst is effective to reduce a spike in ammonia during cyclic operation of the engine between lean and rich operation.
›2.↳ 1The emissions treatment system of claim 1, wherein the SCR catalyst is present in an amount in the range of 0.5 to 2.5 g/in3.d2
The emissions treatment system of claim 1, wherein the SCR catalyst is present in an amount in the range of 0.5 to 2.5 g/in3.
›3.↳ 1The emissions treatment system of claim 1, wherein the molecular sieve comprises a copper chabazite (CuCHA), and the CuCHA is disposed on a downstream…d2+1
The emissions treatment system of claim 1, wherein the molecular sieve comprises a copper chabazite (CuCHA), and the CuCHA is disposed on a downstream carrier.
›4.↳ 3The emissions treatment system of claim 3, wherein the molecular sieve is a copper chabazite SSZ-13.d3
The emissions treatment system of claim 3, wherein the molecular sieve is a copper chabazite SSZ-13.
›5.↳ 1The emissions treatment system of claim 1, wherein the molecular sieve comprises a copper SAPO (CuSAPO), and the CuSAPO is disposed on a downstream ca…d2+1
The emissions treatment system of claim 1, wherein the molecular sieve comprises a copper SAPO (CuSAPO), and the CuSAPO is disposed on a downstream carrier.
›6.↳ 5The emissions treatment system of claim 5, wherein the molecular sieve is copper SAPO-34.d3
The emissions treatment system of claim 5, wherein the molecular sieve is copper SAPO-34.
›7.↳ 1The emissions treatment system of claim 1, wherein the downstream carrier comprises a wall flow filter having a plurality of longitudinally extending …d2+1
The emissions treatment system of claim 1, wherein the downstream carrier comprises a wall flow filter having a plurality of longitudinally extending passages formed by longitudinally extending walls bounding and defining said passages, wherein the passages comprise inlet passages having an open inlet end and a closed outlet end, and outlet passages having a closed inlet end and an open outlet end.
›8.↳ 7The emissions treatment system of claim 7, wherein the filter is coated by the SCR catalyst in the range of about 10% to 100% of the axial length.d3
The emissions treatment system of claim 7, wherein the filter is coated by the SCR catalyst in the range of about 10% to 100% of the axial length.
›9.↳ 1The emissions treatment system of claim 1, wherein the lean NOx trap (LNT) catalytic material comprises a single washcoat layer having a uniform compo…d2
The emissions treatment system of claim 1, wherein the lean NOx trap (LNT) catalytic material comprises a single washcoat layer having a uniform composition.
›10.↳ 1The emissions treatment system of claim 1, wherein the undercoat washcoat layer comprises a support material, at least one precious metal, and at leas…d2
The emissions treatment system of claim 1, wherein the undercoat washcoat layer comprises a support material, at least one precious metal, and at least one NOx sorbent selected from the group consisting of oxides of magnesium, calcium, strontium, barium, lanthanum, cerium, praseodymium, neodymium, and combinations thereof wherein the undercoat washcoat layer is on the carrier; andnthe top washcoat layer comprises a support material, at least one precious metal, and ceria in particulate form, the top washcoat layer being substantially free of alkaline earth components.
›11.↳ 1A method of converting NOx in an exhaust gas stream from a diesel engine or lean burn gasoline engine to N2 comprising: routing the exhaust gas stream…d2+1
A method of converting NOx in an exhaust gas stream from a diesel engine or lean burn gasoline engine to N2 comprising: routing the exhaust gas stream through the emissions treatment system of claim 1.
›12.↳ 11The method system of claim 11, wherein the SCR catalyst is effective to reduce a spike in ammonia by at least about 50% or greater.d3
The method system of claim 11, wherein the SCR catalyst is effective to reduce a spike in ammonia by at least about 50% or greater.
›13.↳ 1The emissions treatment system of claim 1, wherein the SCR catalyst is effective to reduce a spike in ammonia by at least about 50% or greater.d2
The emissions treatment system of claim 1, wherein the SCR catalyst is effective to reduce a spike in ammonia by at least about 50% or greater.
›14.↳ 1The emissions treatment system of claim 1, wherein the ammonia-generating component comprises a platinum group metal selected from platinum, palladium…d2+6
The emissions treatment system of claim 1, wherein the ammonia-generating component comprises a platinum group metal selected from platinum, palladium and rhodium.
›15.↳ 14The emissions treatment system of claim 14, wherein the top washcoat layer further comprises a second platinum group metal component selected from pla…d3+1
The emissions treatment system of claim 14, wherein the top washcoat layer further comprises a second platinum group metal component selected from platinum on a gamma-alumina support.
›16.↳ 15The emissions treatment system of claim 15, wherein the baria is present in an amount of 0.3 to 4.0 g/ft3.d4
The emissions treatment system of claim 15, wherein the baria is present in an amount of 0.3 to 4.0 g/ft3.
›17.↳ 14The emissions treatment system of claim 14, wherein the undercoat washcoat layer comprises platinum on a gamma-alumina support, and ceria, baria and z…d3+3
The emissions treatment system of claim 14, wherein the undercoat washcoat layer comprises platinum on a gamma-alumina support, and ceria, baria and zirconia.
›18.↳ 17The emissions treatment system of claim 17, wherein the amount of loading of the platinum group metal component is in the range of 50 to 200 g/ft3 tot…d4+2
The emissions treatment system of claim 17, wherein the amount of loading of the platinum group metal component is in the range of 50 to 200 g/ft3 total amount in the top and undercoat washcoat layers.
›19.↳ 18The emissions treatment system of claim 18, wherein the platinum, palladium and rhodium are present in an amount in the range of 50 to 200 g/ft3.d5+1
The emissions treatment system of claim 18, wherein the platinum, palladium and rhodium are present in an amount in the range of 50 to 200 g/ft3.
›20.↳ 19The emissions treatment system of claim 19, wherein the top washcoat layer is substantially free of any alkaline earth components.d6
The emissions treatment system of claim 19, wherein the top washcoat layer is substantially free of any alkaline earth components.
›21.↳ 1The emissions treatment system of claim 1, wherein the top washcoat layer comprises a platinum group metal component selected from rhodium on a ceria …d2
The emissions treatment system of claim 1, wherein the top washcoat layer comprises a platinum group metal component selected from rhodium on a ceria support.
›22.↳ 1The emissions treatment system of claim 1, wherein the ammonia-generating component comprises platinum, palladium and rhodium.d2+2
The emissions treatment system of claim 1, wherein the ammonia-generating component comprises platinum, palladium and rhodium.
›23.↳ 22A method of converting NOx in an exhaust gas stream from a diesel engine or lean burn gasoline engine to N2 comprising: routing the exhaust gas stream…d3+1
A method of converting NOx in an exhaust gas stream from a diesel engine or lean burn gasoline engine to N2 comprising: routing the exhaust gas stream through the emissions treatment system of claim 22.
›24.↳ 23The emissions treatment system of claim 23, wherein the top washcoat layer is capable of oxidizing NOx at temperatures below 200° C.d4
The emissions treatment system of claim 23, wherein the top washcoat layer is capable of oxidizing NOx at temperatures below 200° C.
