Catalysts having a blend of platinum on a support with low ammonia storage with a Cu-SCR catalyst or an Fe-SCR catalyst are disclosed. The catalysts can also contain one or two additional SCR catalysts. The catalysts can be present in one of various configurations. Catalytic articles containing these catalysts are disclosed. The catalytic articles are useful for selective catalytic reduction (SCR) of NOx in exhaust gases and in reducing the amount of ammonia slip. Methods for producing such articles are described. Methods of using the catalytic articles in an SCR process, where the amount of ammonia slip is reduced, are also described.

A method, control system, and vehicle system configured to control a selective catalyst reduction (SCR) system subtracts an amount of NO.sub.x present in a tailpipe upstream of the SCR system from an amount of NO.sub.x present in the tailpipe downstream of the SCR injector. A cumulative difference may be determined based on integrating the subtracted NO.sub.x value. The method, control system, and vehicle system are configured to determine whether the cumulative difference exceeds a control threshold, and to set a selected upstream NO.sub.x value as a predetermined model upstream NO.sub.x amount if the cumulative difference exceeds the control threshold, but to set the selected upstream NO.sub.x value as the determined upstream NO.sub.x amount if the cumulative difference does not exceed the control threshold. Thus, the system is reset to the model when downstream NO.sub.x values exceed upstream NO.sub.x values above a threshold, to bring the system back within control.

An exhaust system for the treatment of an exhaust gas comprising a species to be treated, the system comprising: a first gas inlet for providing a flow of exhaust gas; a second gas inlet for providing a flow of heated gas; a plurality of sorbent beds for releasably storing the species; one or more catalysts for decomposing the species; first and second exhaust gas outlets; and a valve system configured to establish independently for each sorbent bed fluid communication in a first or second configuration, wherein: i) in the first configuration the flow of the exhaust gas from the first gas inlet contacts a sorbent bed for storing the species and then passes to the first gas outlet; and ii) in the second configuration the flow of heated gas from the second gas inlet contacts a sorbent bed for releasing the species, passes to one of the one or more catalysts and then passes to the second exhaust gas outlet; wherein the valve system is configured to ensure that at least one sorbent bed is in the first configuration and, preferably at least one other sorbent bed is in the second configuration.

A radio frequency system and method for monitoring an engine-out exhaust emission constituent. The system comprises a housing containing the emission constituent, one or more radio frequency sensors extending into the housing and transmitting and receiving radio frequency signals, and a control unit for controlling the radio frequency signals and monitoring changes in the emission constituent based on changes in one or more parameters of the radio frequency signals. In one embodiment, the control unit measures a rate of change in one or more of the parameters of the radio frequency signals for monitoring a rate of change of the emission constituent including for example the emission rate, accumulation rate, and/or depletion rate of the emission constituent.

An amount of electric power consumption by a battery is reduced, and deterioration of a coil is suppressed by efficiently heating an injector and melting urea crystals at an early stage. A control device for a reducing agent injection device fills the device with a reducing agent at a start-up of an internal combustion engine and executes control for injecting the reducing agent into an exhaust passage of the internal combustion engine by the injector. The control device includes an energization control section that executes energization control in which, after an exhaust temperature of the internal combustion engine becomes equal to or higher than a specified threshold value, a temperature of the injector is increased by energizing the coil of the injector for a specified time and melting of the crystals of the reducing agent precipitated in the injector is promoted.

A exhaust gas purification apparatus is provided with; a substrate having a wall-flow structure and including entry-side cells, exit-side cells, and a porous partition; a first catalyst region formed in small diameter pores having relatively small pore diameters among internal pores in the partition; and a second catalyst region formed in large diameter pores having relatively large pore diameters among the internal pores in the partition. The first catalyst region contains a support and any one or two species of precious metal selected from Pt, Pd, and Rh loaded on the support, while the second catalyst region contains a support and any one or two species of precious metal selected from Pt, Pd, and Rh loaded on the support and other than at least the precious metal present in the first catalyst region.

Extruded honeycomb catalyst bodies and methods of manufacturing same. The catalyst body includes a first oxide selected from the group consisting of tungsten oxides, vanadium oxides, and combinations thereof, a second oxide selected from the group consisting of cerium oxides, lanthanum oxides, zirconium oxides, and combinations thereof, and a zeolite.

An aftertreatment assembly includes a selective catalytic reduction (SCR) device having a catalyst and configured to receive an exhaust gas. A controller is operatively connected to the SCR device. The controller having a processor and a tangible, non-transitory memory on which is recorded instructions for executing a method of model-based monitoring of the SCR device. The method relies on a physics-based model that may be implemented in a variety of forms. The controller is configured to obtain at least one estimated parameter, and at least one threshold parameter based at least partially on a catalyst degradation model. The catalyst degradation model is based at least partially on a predetermined threshold storage capacity (.sub.T). A catalyst status is determined based on a comparison of the estimated and threshold parameters. The operation of the assembly is controlled based at least partially on the catalyst status.

Provided is an ammonia slip catalyst article having supported palladium in a top or upstream layer for oxidation of carbon monoxide and/or hydrocarbons, an SCR catalyst either in the top layer or in a separate lower or downstream layer, and an ammonia oxidation catalyst in a bottom layer. Also provided are methods for treating an exhaust gas using the catalyst article, wherein the treatment involves reducing the concentrations of ammonia and optionally carbon monoxide and/or hydrocarbons in the exhaust gas.

An exhaust gas after-treatment unit for an internal combustion engine, particularly for a motor vehicle, includes a first selective catalytic reduction (SCR) catalytic converter through which the exhaust gas from the internal combustion engine can flow and at least one particle filter for retaining the soot particles from the exhaust gas, The particle filter, which is located downstream from the first SCR catalytic converter, is equipped with a heavy metal and precious metal free catalyzing coating which oxidizes the soot particles retained by the particle filter, where downstream from the particle filter there is a second SCR catalytic converter through which the exhaust gas can flow.