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 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:
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.