摘要:
The present invention is directed to a particle filter to remove soot from the exhaust gas of a diesel engine. The particle filter contains a catalytically active coating on a filter body to accelerate burn-off during a regeneration phase of the soot particles collected on the filter. The particle filter comprises a catalytic coating containing compounds of barium, compounds of magnesium, and at least one element of the platinum group metals. The invention is further directed to a process for accelerated combustion of soot particles collected on the filter from lean exhaust gas of a diesel engine in which the soot particles have a soot ignition temperature and the particle filter is actively regenerated from time to time by raising the temperature of the particle filter above the soot ignition temperature and burning off the soot particles.
摘要:
The present invention is directed to a particle filter to remove soot from the exhaust gas of a diesel engine. The particle filter contains a catalytically active coating on a filter body to accelerate bum-off during a regeneration phase of the soot particles collected on the filter. The particle filter comprises a catalytic coating containing compounds of barium, compounds of magnesium, and at least one element of the platinum group metals. The invention is further directed to a process for accelerated combustion of soot particles collected on the filter from lean exhaust gas of a diesel engine in which the soot particles have a soot ignition temperature and the particle filter is actively regenerated from time to time by raising the temperature of the particle filter above the soot ignition temperature and burning off the soot particles.
摘要:
The invention provides a process for reducing the amounts of carbon monoxide, hydrocarbons and soot particles in the lean exhaust gas from an internal combustion engine using a particle filter, wherein the soot particles have a soot ignition temperature TZ and the particle filter is regenerated from time to time by raising the temperature of the particle filter to above the soot ignition temperature and burning the soot particles, wherein the temperature of the filter is increased to the temperature required to initiate soot ignition by burning additional fuel on the catalytic coating when the exhaust gas back pressure reaches a predetermined value. The process is characterised in that the particle filter is provided with a catalytic coating comprising a first group of components for reducing the ignition temperature of soot, said first group of components contains at least one oxygen storage component and at least one platinum group metal selected from the group consisting of platinum, palladium and rhodium. In a preferred embodiment of the process the catalytic coating further comprises a second group of components for oxidising carbon monoxide and hydrocarbons, said second group of components comprises at least a support material selected from the group consisting of aluminium oxide, silicon oxide, titanium oxide, zirconium oxide and zeolite and at least one platinum group metal selected from the group consisting of platinum, palladium and rhodium deposited on said support materials.
摘要:
The present invention describes an exhaust-gas purification system for an internal combustion engine made of an oxidation catalyst arranged close to the engine, a subsequent hydrocarbon adsorber and a particulate filter arranged downstream thereof and provided with another oxidation catalyst. The oxidation catalyst ensures that emission limits with respect to carbon monoxide and hydrocarbons are satisfied in normal driving mode. During operating states with exhaust-gas temperatures below about 200° C., the oxidation catalyst can no longer oxidize carbon monoxide and hydrocarbons. Instead, the hydrocarbons are adsorbed by the hydrocarbon adsorber during these operating phases. In order to initiate the periodical regeneration of the particulate filter, the exhaustgas temperature of the internal combustion engine is raised by engine modifications. The increased exhaust-gas temperature leads to desorption of the previously stored hydrocarbons, which are then burned at the oxidation catalyst of the particulate filter, thereby supporting the regeneration of the particulate filter.
摘要:
The present invention provides an exhaust gas treatment unit for an internal combustion engine. A first catalyst unit produces ammonia from corresponding constituents in a rich exhaust gas composition. A second catalyst unit that is located downstream of the first catalyst unit temporarily stores the ammonia produced by the first catalyst unit in the presence of a rich exhaust gas composition. In the presence of a lean exhaust gas composition, the nitrogen oxides present in the exhaust gas are subjected to a reduction reaction using the temporarily stored ammonia as reducing agent. The exhaust gas treatment unit also contains a third catalyst unit that is located between the other two catalyst units, and oxidizes the nitrogen oxides present in the exhaust gas at lean exhaust gas conditions to a such an extent that 25 to 75 vol. % of the nitrogen oxides entering the second catalyst unit consist of nitrogen dioxide.
摘要:
The invention relates to a catalyst arrangement for purifying the exhaust gases of internal combustion engines operated under lean conditions. It is proposed that a thinwalled, porous carrier be coated on one side with a nitrogen oxide storage catalyst and on the other side with an SCR catalyst. When the exhaust gas is passed through the catalytic coatings and the support material, a significant improvement in the nitrogen oxide conversion is achieved compared to a series arrangement of the catalysts on separate carriers. Wall flow filters have been found to be useful as thin-walled carriers.
摘要:
The invention proposes a particulate filter having a catalytic coating which contains two catalysts arranged one behind the other. The first catalyst is located in the gas inlet region of the filter and contains a palladium/platinum catalyst. The second catalyst is arranged downstream of the first catalyst and preferably contains platinum alone as catalytically active component. The combination of these two catalysts provides the coated filter with a good ageing stability and resistance to sulphur poisoning.
摘要:
Coating a wall-flow filter with a catalytically active coating generally increases the exhaust-gas backpressure in the filter. The increase in the exhaust-gas backpressure is particularly pronounced if a slurry of fine-particle catalyst materials is used for the coating operation. The increase in the exhaust-gas backpressure can be restricted to a tolerable level if, prior to the coating operation, the slurry is so finely milled that virtually the entire mass of the catalyst materials is introduced into the pores of the filter and deposited on the inner surfaces of the pores. This is the case if the d90 diameter of the particles in the slurry is reduced to below 5 μm by milling.
摘要:
The invention proposes a particulate filter having a catalytic coating which contains two catalysts arranged one behind the other. The first catalyst is located in the gas inlet region of the filter and contains a palladium/platinum catalyst. The second catalyst is arranged downstream of the first catalyst and preferably contains platinum alone as catalytically active component. The combination of these two catalysts provides the coated filter with a good ageing stability and resistance to sulphur poisoning.
摘要:
An exhaust gas treatment unit for the selective catalytic reduction of nitrogen oxides under lean exhaust gas conditions which contains at least one catalyst with catalytically active components for selective catalytic reduction (SCR components). The exhaust gas treatment unit is characterised in that the catalyst also contains, in addition to SCR components, at least one storage component for nitrogen oxides (NOx components).