Apparatus and method for filtering particulate and reducing NOx emissions

A particulate trap system for an internal combustion engine having a nitrogen oxide (NOx) reduction aftertreatment system, comprising:

• at least one particulate trap module to accept engine exhaust gas including a plurality of passages having porous walls for filtering exhaust gas, the porous walls having inner surfaces coated with precious metal catalysts and NOx adsorber material;
• means for passing a majority of lean exhaust gas through the porous walls of a majority of the plurality of passages, the porous walls removing particulate and oxidizing the particulate via the precious metal catalysts at an acceptable temperature range;
• means for converting NOx to NO2 in-the plurality of passages via the precious metal catalyst at the acceptable temperature range;
• means for storing the NO2 in the NOx adsorber material at the acceptable temperature range;
• and
• means for adding fuel to a minority flow of the exhaust gas to convert it to a rich mixture and for passing the minority flow of exhaust gas through a minority of the plurality of passages, thereby causing the rich mixture of exhaust gas flow to release the stored NO2 for reduction by CO in the rich mixture flow of exhaust gas in the presence of precious metal catalyst at the acceptable temperature range forming CO2 and N2.

A method for reducing nitrogen oxide (NOx) in a particulate trap system used with an internal combustion engine, the steps comprising:

• accepting exhaust gas to at least one particulate trap module including a plurality of passages having porous walls;
• passing a majority of lean exhaust gas through a majority of the plurality of passages having the porous walls,
• filtering and removing particulate from the exhaust gas through the porous walls having inner surfaces coated with precious metal catalysts and NOx adsorber material;
• oxidizing the particulate via the precious metal catalysts at an acceptable temperature range;
• converting NOx to NO2 in the plurality of passages via the precious metal catalyst;
• storing the NO2 in the NOx adsorber material;
• adding fuel to a minority flow of the exhaust gas to convert it to a rich mixture;
• and passing the minority flow of exhaust gas through a minority of the plurality of passages, thereby causing the rich mixture of exhaust gas flow to release stored NO2 for reduction by CO in the rich mixture flow of exhaust gas in the presence of precious metal catalyst at the acceptable temperature range forming CO2 and N2.

A method for filtering and regenerating a particulate trap system for an internal combustion engine having a nitrogen oxide (NOx) reduction aftertreatment system, comprising:

• accepting engine exhaust gas via an at least one particulate trap module having a plurality of passages having porous walls for filtering exhaust gas, wherein the passages have porous walls with inner surfaces coated with precious metal catalysts and NOx adsorber material;
• passing a majority of lean exhaust gas through the porous walls of a majority of the plurality of passages;
• removing the particulate via the porous walls and oxidizing the particulate via the precious metal catalysts at an acceptable temperature range;
• converting NOx to NO2 in the plurality of passages via the precious metal catalyst at an acceptable temperature range;
• storing the NO2 in the NOx adsorber material at the acceptable temperature range;
• and
• adding fuel to a minority flow of the exhaust gas to convert it to a rich mixture and for passing the minority flow of exhaust gas through a minority of the plurality of passages, thereby causing the rich mixture of exhaust gas flow to release the stored NO2 for reduction by CO in the rich mixture flow of exhaust gas in the presence of precious metal catalyst at the acceptable temperature range forming CO2 and N2.