Control Strategy for the Removal of NOX from Diesel Engine Exhaust using Hydrocarbon Selective Catalytic Reduction

A unique catalyst developed using high-throughput discovery techniques in collaboration with BASF Corporation and Accelrys, Inc. was investigated at General Motors under simulated diesel engine exhaust feed conditions for the selective catalytic reduction of NOx. A hydrocarbon mixture was used as the reductant to model the multi-component nature of diesel fuel and the catalyst was evaluated over a wide range of temperatures (150-550 degrees C) relevant to light-duty diesel exhaust. This report investigates the effects of NOx (as NO or NO2), hydrocarbon concentration level (HC: NOx ratio), oxygen concentration, NO concentration, catalyst space velocity, catalyst temperature, and the copresence of hydrogen on steady-state NOx reduction activity. Using these results, a control strategy was developed to maximize NOx conversion over the wideranging exhaust conditions likely to be encountered in light-duty diesel applications.