Patent ID: 7135153

Claim:
A system for treating NOx emissions from a diesel engine that has at least one internal combustion chamber for combusting diesel fuel and has a main exhaust line that carries exhaust from the engine, the exhaust having a range of exhaust gas temperatures typical for a vehicular diesel engine, the system comprising: an auxiliary fuel line from the engine's diesel fuel supply source, separate from the main fuel supply line to the engine; a partial oxidation unit located on the auxiliary fuel line, external to the internal combustion chamber and off-line the main exhaust line; an air intake line for delivering air to the partial oxidation unit; an output line for delivering a hydrogen-enhanced gas mixture from the partial oxidation unit to the main exhaust line; wherein the partial oxidation unit is operable to receive air via the air intake line, to receive diesel fuel via the auxiliary fuel line, and to at least partially oxidize the fuel to produce the hydrogen-enhanced gas mixture; a ruthenium-based hydrogen selective catalytic reduction (H-SCR) unit, located in-line on the main exhaust line, operable to receive the hydrogen-enhanced gas mixture from the partial oxidation unit, and to use hydrogen in the hydrogen-enhanced gas mixture to continuously reduce NOx emissions in the exhaust line to nitrogen; wherein the H-SCR unit is further operable to reduce the NOx emissions to nitrogen under the range of exhaust gas temperatures; means for determining the ratio of NO to NO2 in the exhaust gas; and a metering device on the output line for maintaining a ratio of the hydrogen to NOx in the main exhaust line, on the basis of: the ratio of NO to NO2 a substantially 1:1 molar ratio of the hydrogen to NO, and a substantially 2:1 molar ratio of the hydrogen to NO2.