A commercial NOx-storage catalyst for gasoline applications containing platinum, palladium and rhodium together with Ba/CeO2/Al2O3 has been sulfated on the engine bench at 390 and 510°C with nominal exposures of 0.3 and 1.3gsulphur/l catalyst. Exposures of 0.3g/l are too low to have a notable impact on the catalytic performance. At 390°C, the sulphur is quantitatively adsorbed as opposed to 510°C. Sulphur is mainly adsorbed at the inlet side of the catalyst thereby shielding the downstream region. Desulfation on synthetic gas bench at 700°C leads to a removal of 50% of the sulphur. The residual sulphur is more evenly distributed along the length of the catalyst compared to the sulphur profile in the sulfated catalyst. This leads to an improvement of the NOx-activity at the inlet side and a drop in NOx-performance at the outlet side after desulfation. Results from SEM–EDX, TPD, TPR and IR suggest that the barium component is selectively poisoned by the sulphur while alumina and ceria are not affected significantly. The insufficient desulfation of the catalyst is almost entirely due to the incomplete sulphur removal from the barium sites. In the desulfated state the IR and TPD-data suggest the presence of barium carbonate species of low thermal stability together with bulk carbonate. After sulfation the IR data indicate the presence of different sulphate species, both bulk and surface phases. Thermal ageing and sulphur poisoning affect different parts of the operational temperature window of the NOx-storage catalyst. While thermal stress alone mainly affects low temperature NOx-performance, sulphur poisoning mainly reduces high temperature activity. The results of this work help to identify strategies to improve both the sulfur resistance of the catalyst and the operational conditions for a better management of the NOx-trap system.

A commercial NOx-storage catalyst for gasoline applications containing Ba/CeO 2 /Al 2 O 3 , platinum, palladium and rhodium has been sulfated on the engine bench at 390 and 510°C with a nominal exposure of 1.3 g sulfur/liter catalyst. Lower exposures proved too low to have a notable impact on the catalytic performance. At 390°C the sulfur is completely adsorbed while at 510°C only partial adsorption is being observed. Sulfur is mainly deposited at the catalyst inlet thereby shielding the downstream region. Desulfation on synthetic gas bench at 700°C leads to a partial removal of the sulfur. The residual sulfur is more evenly distributed along the length of the catalyst compared to the sulfur profile in the sulfated catalyst. This causes an improvement of the NOx-activity at the inlet side while the NOx-performance at the outlet side decreases after desulfation. Characterisation with SEM-EDX, TPD, TPR and IR suggests that the barium component is selectively poisoned by the sulfur while alumina and ceria are not affected significantly. In the desulfated state the IR and TPD-data suggest the presence of barium carbonate species of low thermal stability together with bulk carbonate. After sulfation the IR data indicate the presence of different sulphate species, both bulk and surface phases. Thermal aging alone mainly affects low temperature NOx-performance, while sulfur poisoning mainly reduces high temperature activity.

Catalytically coated particulate filter having a first and a second end face and an axial length L, characterized in that the particulate filter is starting from the first end face to a fraction of its length L with a first and coated subsequently with a second catalyst and the first catalyst platinum and palladium on the first substrates and the second catalyst comprises platinum and palladium on the second carrier material and wherein the weight ratio of palladium to platinum in the first catalyst is between 10: 1 and 1:50 and the weight ratio of palladium to platinum in the second catalyst is less than the corresponding weight ratio in the first catalyst.

The present invention describes an exhaust gas purification system for an internal combustion engine of a close-coupled oxidation catalyst, and a subsequent hydrocarbon adsorber arranged one behind it, provided with a further oxidation catalyst, particulate filter. The oxidation catalyst ensures compliance with the emission limit values ​​regarding carbon monoxide and hydrocarbons during normal vehicle operation. While operating states with exhaust gas temperatures below about 200 ° C, the oxidation catalyst can not oxidize carbon monoxide and hydrocarbon. Instead, the hydrocarbons are adsorbed during these operating phases of hydrocarbon adsorber. To initiate the regularly scheduled regeneration of the particulate filter, the exhaust temperature of the engine is increased by engine measures. The increased exhaust gas temperature leads to the desorption of the previously stored hydrocarbons, which are then burned at the oxidation catalyst of the particulate filter and thus support the regeneration of the particulate filter.

The invention relates to a method and apparatus for operating a drive system of a motor and an emission control system with a catalyst, wherein the engine emits an exhaust gas having an exhaust gas temperature and the catalyst has a catalytic activity for purifying the exhaust gas. The method is characterized in that an aging-induced decrease in the catalytic activity of the catalyst is at least temporarily compensated by increasing the exhaust gas temperature of the engine.

1. ABSTRACT In this paper results obtained with different particulate matter (PM) reduction technologies are presented. Diesel oxidation catalysts (DOC) are well known as a reliable PM reduction technology which can efficiently remove the soluble organic fraction (SOF) but which has no effect on the solid particles in PM. A drawback is that in combination with high sulfur fuel, oxidation of SO 2 to SO 3 by the DOC can occur, resulting in an increase of PM emissions. An alternative technology that is proven to significantly reduce soot emissions comprises diesel particulate wall-flow filters. High filtration efficiencies of up to 90% and beyond are feasible. The main obstacle is the combustion of the trapped soot. As shown in this paper, the application of a catalyst coating to the filter aids the filter regeneration by lowering the balance-point temperature. The main disadvantages of wall-flow filters are an increase in back-pressure and possible plugging caused by oil-ash accumulations. A potential solution that is presented in this paper is the newly developed continuous soot combustion catalyst (CSCC). This technology achieves higher PM conversions compared to conventional diesel oxidation catalysts. A key feature of this technology is the use of a special flow-through substrate possessing more porous walls and a higher geometric surface area than standard DOC substrates. With such substrates the residence time is increased, so that the trapped soot can be oxidized continuously by appropriately designed soot combustion catalysts.

The invention relates to a method for coating a catalyst support with a catalytically active coating by using a coating dispersion, wherein the catalyst support contains two partial structures at least, which are distinguished by their capacity for Beschichtungsdisperion. The method is characterized in that the capacity of the partial structures changed relative to each other by preempting the catalyst support with a burn-out material or fluid, and then applied the catalytic coating in a known manner to the filter body, is dried and / or calcined.

The reduction of nitrogen oxide emissions which contribute significantly to photochemical smog and also to acid rain is one of the most challenging targets of today’s engine development. Several measures to reduce NOX emissions, such as NOX adsorbers and SCR catalysts, are currently under development.

The invention relates to an exhaust gas purification system for an internal combustion engine having a first catalyst unit that generates ammonia from corresponding exhaust gas components in rich exhaust gas composition, and one of the first downstream second catalytic converter unit, which temporarily stores the ammonia generated by the first catalyst unit in rich exhaust gas composition and contained in a lean exhaust gas composition in the exhaust gas nitrogen oxides reduction reaction undergoes as a reducing agent, using the cached ammonia. The exhaust gas purification system is characterized in that the two catalyst units intermediate, third catalyst unit oxidized at a lean exhaust gas composition, the nitrogen oxides contained in the exhaust gas to a degree to nitrogen dioxide, the nitrogen oxides contained in the exhaust gas entering the second catalyst unit to 25 to 75 vol .-% consist of nitrogen dioxide.

Method for operating an exhaust gas purification system for an internal combustion engine having a first catalyst unit that generates ammonia from corresponding exhaust gas components in rich exhaust gas composition, and one of the first downstream second catalytic converter unit, which temporarily stores the ammonia generated by the first catalyst unit in rich exhaust gas composition and contained in a lean exhaust gas composition in the exhaust gas subjecting nitrogen oxides reduction reaction using the intermediately stored ammonia as a reducing agent, wherein an intermediate the two catalyst units, third catalyst unit, the nitrogen oxides contained in the exhaust gas is oxidized during lean exhaust gas composition to an extent to nitrogen dioxide, the nitrogen oxides contained in the exhaust gas entering the second catalyst unit 25 to 75 vol .-% composed of nitrogen dioxide.

Die Erfindung betrifft einen Redox-Katalysator fur die selektive katalytische Reduktionder im Abgas von Dieselmotoren enthaltenen Stickoxide mittels Ammoniak. Der Reduktionskatalysatorenthalt eine katalytisch aktive Masse, die auf dem Feststoffsaure-SystemTiO 2 /WO 3 /MoO 3 /V 2 O 5 /SiO 2 /SO 3 basiert und einen Oxidationskatalysator aufder Basis der Platingruppenmetalle Platin und Palladium. Der Reduktionskatalysator,liegt in Form eines zylindrischen Wabenkatalysators mit einer Eintritts- und einer Austrittsstimflachevor. Der Oxidationskatalysator ist auf einem der Austrittsstimflachebenachbarten Abschnitt des Reduktionskatalysators aufgebracht. Der Redox-Katalysatorist dadurch gekennzeichnet, das die katalytisch aktive Masse des Reduktionskatalysatorsals Tragermaterial fur die Platingruppenmetalle des Oxidationskatalysators dient.

The invention relates to a process for removing soot from the exhaust gas of a diesel engine by oxidizing the nitrogen monoxide contained in exhaust gas to nitrogen dioxide, separating the soot from the exhaust gas stream and oxidizing the soot using the nitrogen dioxide produced. The method is characterized in that the described process performed in each case in at least two consecutive process stages and the soot is separated in every stage of the process with an efficiency W from 0.05 to 0.95 from the exhaust stream, wherein each process stage has a transmission for soot in accordance with T = 1 - W can be allocated and the total transmission of the process for carbon black as a product of the transmissions of all the process steps is given.