摘要:
A chemical process for treating exhaust gas from a vehicular internal combustion engine with a lean/rich cycle using a selective catalytic reduction (SCR) catalyst comprises exposing the SCR catalyst in a NOx adsorber catalyst (NAC)+(downstream)SCR catalyst system to at least one reactant including nitrogen oxides and reducing the nitrogen oxides with a nitrogenous reductant, wherein the SCR catalyst comprises copper and a small pore molecular sieve having a maximum ring size of eight tetrahedral atoms and wherein the nitrogenous reductant is metered into a flowing exhaust gas only when the SCR catalyst is at above 100°C.
摘要:
A system for treating exhaust gas from a vehicular lean-burn internal combustion engine with a lean/rich cycle, which system comprising a NO x adsorber catalyst and a downstream NH 3 -selective catalytic reduction (SCR) catalyst, wherein the NH 3 -SCR catalyst comprises copper supported on a molecular sieve, wherein the molecular sieve (a) has a maximum ring size of eight tetrahedral atoms; (b) is selected from the group consisting of aluminosilicate molecular sieves, metal-substituted aluminosilicate molecular sieves, and aluminophosphate molecular sieves; and (c) has a CHA Framework Type Code.
摘要:
A system for treating exhaust gas from a vehicular lean-bum internal combustion engine with a lean/rich cycle comprises a NO x adsorber catalyst and a downstream NH 3 -selective catalytic reduction (SCR) catalyst, wherein the NH 3 -SCR catalyst comprises copper supported on a molecular sieve, wherein the molecular sieve (a) has a maximum ring size of eight tetrahedral atoms; (b) is selected from the group consisting of aluminosilicate molecular sieves, metal-substituted aluminosilicate molecular sieves, and aluminophosphate molecular sieves; and (c) has a Framework Type Code selected from the group consisting of AEI, LEV, ERI and DDR.
摘要:
Provided is an ammonia slip catalyst article having supported palladium in a top or upstream layer for oxidation of carbon monoxide and/or hydrocarbons, an SCR catalyst either in the top layer or in a separate lower or downstream layer, and an ammonia oxidation catalyst in a bottom layer. Also provided are methods for treating an exhaust gas using the catalyst article, wherein the treatment involves reducing the concentrations of ammonia and optionally carbon monoxide and/or hydrocarbons in the exhaust gas.
摘要:
A method of using a catalyst comprises exposing a catalyst to at least one reactant in a chemical process. The catalyst comprises copper and a small pore molecular sieve having a maximum ring size of eight tetrahedral atoms. The chemical process undergoes at least one period of exposure to a reducing atmosphere. The catalyst has an initial activity and the catalyst has a final activity after the at least one period of exposure to the reducing atmosphere. The final activity is within 30% of the initial activity at a temperature between 200 and 500°C.
摘要:
A system for treating an exhaust gas from a lean burn internal combustion engine comprises a NOx adsorber catalyst (NAC) and a downstream selective catalytic reduction (SCR) catalyst, wherein the SCR catalyst comprises a copper promoted small pore molecular sieve having a maximum ring size of eight tetrahedral atoms, wherein the system meters nitrogenous reductant into a flowing exhaust gas only when it is determined that the SCR catalyst is at above 100 °C.
摘要:
A chemical process for treating exhaust gas from a vehicular internal combustion engine with a lean/rich cycle using a selective catalytic reduction (SCR) catalyst, which chemical process comprising exposing the SCR catalyst in a NOx adsorber catalyst (NAC)+(downstream)SCR catalyst system to at least one reactant including nitrogen oxides and reducing the nitrogen oxides with NH 3 nitrogenous reductant generated over the NAC during periodic rich regeneration events, wherein the SCR catalyst comprises copper and a small pore molecular sieve having a maximum ring size of eight tetrahedral atoms having the AEI Framework Type Code.
摘要:
A chemical process for treating exhaust gas from a vehicular internal combustion engine with a lean/rich cycle using a selective catalytic reduction (SCR) catalyst, which chemical process comprising exposing the SCR catalyst in a NOx adsorber catalyst (NAC)+(downstream)SCR catalyst system to at least one reactant including nitrogen oxides and reducing the nitrogen oxides with NH 3 nitrogenous reductant generated over the NAC during periodic rich regeneration events, wherein the SCR catalyst comprises copper and a small pore molecular sieve having a maximum ring size of eight tetrahedral atoms having the AEI Framework Type Code.
摘要:
A system for treating exhaust gas from a vehicular lean-burn internal combustion engine with a lean/rich cycle, which system comprising a NO x adsorber catalyst and a downstream NH 3 -selective catalytic reduction (SCR) catalyst, wherein the NH 3 -SCR catalyst comprises copper supported on a molecular sieve, wherein the molecular sieve (a) has a maximum ring size of eight tetrahedral atoms; (b) is selected from the group consisting of aluminosilicate molecular sieves, metal-substituted aluminosilicate molecular sieves, and aluminophosphate molecular sieves; and (c) has a CHA Framework Type Code.