Abstract:
An exhaust gas treatment system (14) includes a selective catalytic reduction (SCR) catalyst (38) and a dosing control (80) responsive to exhaust gas operating conditions for controlling the dosing rate of a reductant such as aqueous urea into the exhaust stream. The dosing control is configured to reduce the dosing rate when either a sudden increase in the exhaust mass air flow is detected or when an exhaust gas temperature gradient is in an increasing state. The dosing control is also configured to shut-off dosing when a measured ammonia concentration level exceeds an ammonia slip trip level, provided that the exhaust gas temperature gradient is also in an increasing state.
Abstract:
An exhaust gas treatment system (14) includes a selective catalytic reduction (SCR) catalyst (38) and a dosing control (80) responsive to exhaust gas operating conditions for controlling the dosing rate of a reductant such as aqueous urea into the exhaust stream. The dosing control is configured to reduce the dosing rate when either a sudden increase in the exhaust mass air flow is detected or when an exhaust gas temperature gradient is in an increasing state. The dosing control is also configured to shut-off dosing when a measured ammonia concentration level exceeds an ammonia slip trip level, provided that the exhaust gas temperature gradient is also in an increasing state.
Abstract:
Disclosed is a method for direct application of a catalyst to a substrate for treatment of atmospheric pollution including ozone. The method includes applying a catalytic metal to a substrate utilizing a thermal spray process. The process can be utilized to apply a base metal such as copper to a substrate and the base metal becomes the catalytically active oxide during and following application to the substrate. This system replaces a multi-step process within a single step process to provide a catalytically active surface that can be utilized to reduce ground level ozone and other atmospheric pollutants.
Abstract:
A method for making a sensor (10) is disclosed, comprising mixing a metal oxide with a polymer to create a composition. The composition is applied to at least a portion of the sensing element (10) comprising two electrodes (20, 22) with an electrolyte (30) disposed therebetween, and calcined to form a protective coating. A gas sensor (10) created in accordance with the above-referenced method is also disclosed.