MANGANESE-BASED OXIDES PROMOTED LEAN NOx TRAP (LNT) CATALYST

摘要

MnO_x-containing, base-metal oxide mixtures (e.g., MnO_x—CeO₂) are useful NO_x oxidation catalyst materials and NO_x storage materials in lean-burn engine exhaust gas treatments using Lean NO_x Trap (LNT) systems. These oxidation catalyst materials are used in combination with a NO_x storage material and a NO_x reduction material. MnO_x-containing oxide mixtures can replace platinum (Pt) in LNT systems where the exhaust of the engine is repeatedly varied between a relatively long fuel-lean mode of operation and a relatively short fuel-rich mode of operation. The combination of the MnO_x oxidation catalyst, NO_x storage material, and NO_x reduction catalyst material serves to complete the oxidation of unburned hydrocarbons and carbon monoxide, and to convert NO_x to nitrogen.