US Patent 10005031 Dual-layer catalyst

A dual-layer catalyst includes a substrate, a first layer disposed on the substrate, and a second layer disposed on the first layer. The first layer includes a first catalyst for storing NOx when the first catalyst has a temperature below an active temperature of a second catalyst. The first catalyst is to release the stored NOx when the first catalyst is heated to the active temperature of the second catalyst. The second layer includes the second catalyst for ammonia Selective Catalytic Reduction of the released NOx. The dual-layer catalyst is to be included in a catalytic converter and a catalyst system for reducing NOx emissions from a diesel engine, the NOx emissions including NOx emitted during a predetermined cold-start time period.