Abstract: A method for remediating a NOx-containing lean diesel emission includes providing a LNT/SCR catalyst system including a SCR catalyst and a first and second LNT. The SCR catalyst is disposed downstream of the second LNT which is disposed downstream of the first LNT. The lean NOx-containing diesel emission is introduced to the first LNT with the NOx being absorbed on to the first LNT forming a substantially NOx-free lean diesel emission. An exotherm generating agent is introduced to the substantially NOx-free diesel emission between the first LNT and the second LNT to form a reactive lean diesel emission. The reactive lean diesel emission is introduced to the second LNT generating a quantity of heat effective for desorbing absorbed NOx. A reducing agent is introduced into the desorbed NOx between the second LNT and SCR catalyst. The desorbed NOx diesel emission is remediated in the SCR catalyst.

Abstract: A method of removing hydrogen sulfide from an emissions stream is disclosed, wherein the method includes directing the emissions stream into a hydrogen sulfide converter having a metal oxide catalyst, adsorbing the hydrogen sulfide in the emissions stream to the metal oxide catalyst in the hydrogen sulfide converter, reacting the hydrogen sulfide with at least one of an oxidant and a reductant in the hydrogen sulfide converter to chemically transform the hydrogen sulfide, and adjusting an air-fuel ratio of the emissions stream based on exhaust temperature of an emission control device, where the adjustment varies a duration of at least one of lean and rich operation to perform the adsorbing and reacting even as exhaust temperature varies.

Abstract: Performance characteristics of a catalytic device are determined based on a particle size of a particulate component of the catalytic device. In this way, aging of a catalytic device can be accounted for in the calculation of performance characteristics.

Abstract: A mechanical apparatus including a combustion engine, a conduit for transporting an exhaust stream away from the engine, a first catalytic NOx storage and conversion region disposed along the conduit, and a second catalytic NOx storage and conversion region disposed along the conduit at a location downstream from the first catalytic NOx storage and conversion region is disclosed. Each of the first catalytic NOx storage and conversion region and the second catalytic NOx storage and conversion region includes at least one catalytic metal configured to convert NOx to NO2 when the engine is supplied a lean air/fuel mixture, and at least one NOx adsorbing compound configured to adsorb NO2 for storage when the engine is supplied a lean air/fuel mixture, and wherein the one of the first and the second catalytic NOx storage and conversion regions has a lower concentration of catalytic metal than the other of the first and second catalytic NOx storage and conversion regions.

Abstract: A method of desulfating a catalytic NOx storage and conversion device is disclosed, wherein the method includes determining an amount of sulfur stored in the catalytic NOx storage and conversion device; determining an interval for exposing the catalytic NOx storage and conversion device to a rich exhaust stream based upon the determined amount of sulfur stored, wherein the interval is longer for lower amounts of sulfur stored and shorter for higher amounts of sulfur stored; and exposing the catalytic NOx storage and conversion device to the rich exhaust stream for the determined interval.

Abstract: In an apparatus having a combustion engine and an emissions system including a catalytic converter and a metal oxide catalyst disposed downstream of the catalytic converter, a method of controlling a chemical transformation of hydrogen sulfide in an emissions stream to a less-noxious sulfur-containing compound is disclosed. The method includes reacting the hydrogen sulfide with the metal oxide catalyst to form a metal sulfide, monitoring a saturation of the metal oxide catalyst with the metal sulfide, and when a predetermined saturation of metal sulfide on the metal oxide is reached, changing an air/fuel ratio supplied to the combustion engine.

Abstract: A method is described for controlling lean and rich operation of an internal combustion engine coupled to a lean NOx trap. In one example, the termination of the lean air-fuel mixture is based on an oxygen storage capacity and temperature of the NOx trap. In another example, the level and duration of rich air-fuel ratio purging operation is also controlled based on the oxygen storage capacity of the NOx trap.

Abstract: A method is described for controlling lean and rich operation of an internal combustion engine coupled to a lean NOx trap. In one example, the termination of the lean air-fuel mixture is based on an oxygen storage capacity of the NOx trap. In another example, the level and duration of rich air-fuel ratio purging operation is also controlled based on the oxygen storage capacity of the NOx trap.

Abstract: A catalytic converter catalyst diagnostic system comprising: a catalytic converter having a catalyst; a first sensor placed in a flow path of an engine exhaust gas flowing into the catalytic converter and providing a first measurement signal indicative of a temperature of the engine exhaust gas before it enters the catalytic converter catalyst; a second sensor mounted in or behind the catalytic converter catalyst and providing a second measurement signal indicative of a temperature of the catalytic converter catalyst; and a controller coupled to the first and second sensors and receiving the first and second measurement signals therefrom, wherein the controller determines a value indicative of exothermic activity of the catalytic converter responsive to the first and second measurement signals and compares the value indicative of exothermic activity to a threshold value, wherein values below the threshold value are indicative of an improperly operating catalytic converter catalyst.

Abstract: A catalytic treatment device diagnostic for an automotive exhaust system having at least two catalytic treatment devices wherein reduced oxygen storage capacity of each of the devices may be diagnosed without significant loss in engine air/fuel ratio control precision by varying the source of an actual air/fuel ratio feedback signal from a sensor positioned upstream of the devices during normal operation to a sensor mounted downstream of at least one of the devices during a diagnostic period. Measurable change in the oxygen content of exhaust gas passing through each of such devices then becomes available for analysis during the diagnostic period.