摘要:
This invention relates to a method of operating a catalyst for treating the exhaust gas of an internal combustion engine, the catalyst comprising, in addition to catalytically active noble metals, also storage components for storing hydrocarbons. During engine operating phases at low exhaust-gas temperatures, such a catalyst stores the hydrocarbons contained in the exhaust gas without burning them. When the exhaust-gas temperature rises, these hydrocarbons are desorbed again and then oxidized at the catalytically active noble metals. This process can lead to uncontrolled, vigorous combustion of the hydrocarbons stored on the catalyst and, therefore, damage to the catalyst. According to the invention, this damage is avoided by continuously calculating the respective loading of the storage components with hydrocarbons and repeatedly regenerating the storage components depending on the loading by temporarily raising the exhaust-gas temperature before damage to the catalyst can occur.
摘要:
This invention relates to a method of operating a catalyst for treating the exhaust gas of an internal combustion engine, the catalyst comprising, in addition to catalytically active noble metals, also storage components for storing hydrocarbons. During engine operating phases at low exhaust-gas temperatures, such a catalyst stores the hydrocarbons contained in the exhaust gas without burning them. When the exhaust-gas temperature rises, these hydrocarbons are desorbed again and then oxidized at the catalytically active noble metals. This process can lead to uncontrolled, vigorous combustion of the hydrocarbons stored on the catalyst and, therefore, damage to the catalyst. According to the invention, this damage is avoided by continuously calculating the respective loading of the storage components with hydrocarbons and repeatedly regenerating the storage components depending on the loading by temporarily raising the exhaust-gas temperature before damage to the catalyst can occur.
摘要:
A catalyst for purifying the exhaust gases from diesel engines. The catalyst contains a zeolite mixture of several zeolites with different moduli and platinum group metals as well as further metal oxides from the group aluminum silicate, aluminum oxide and titanium oxide, wherein the aluminum silicate has a ratio by weight of silicon dioxide to aluminum oxide of 0.005 to 1 and the platinum group metals are deposited on only the further metal oxides.
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).
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:
A process for checking the operability of an exhaust gas purification catalyst for diesel engines, which has a light-off temperature and a degree of conversion rCO for carbon monoxide (CO), by direct measurement of the carbon monoxide concentration in combination with a temperature measurement. To evaluate the remaining catalytic activity of the catalyst the difference &Dgr;T between the current catalyst exit temperature TE of the exhaust gas and the light-off temperature TCO,50%,fresh of the fresh catalyst for carbon monoxide stored as a function of the speed and load &Dgr;T=TE−TCO,50%,fresh is determined and the degree of conversion rCO for carbon monoxide is ascertained.
摘要:
An oxidation catalyst for internal combustion engines which contains platinum on a finely divided support material and containing lead as a promoter. The catalytic activity of the oxidation catalyst can be increased greatly by promoting the catalyst with lead at a molar ratio of lead to platinum of 2:1. The light-off temperatures of the promoted catalyst are well below the corresponding temperatures for a conventional, lead-free catalyst.
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:
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 present invention relates to an exhaust-gas purification system for the selective catalytic reduction of nitrogen oxides. The system includes at least one catalyst having catalytically active components for the selective catalytic reduction (SCR components). An NOx storage catalyst (5) is arranged upstream of the SCR catalyst (3) in the exhaust-gas purification system. For performing the selective catalytic reduction, metering means (8) for supplying a compound decomposable into ammonia is provided between the NOx storage catalyst and the SCR catalyst (3). At low exhaust-gas temperatures, the NOx storage catalyst (5) adsorbs the nitrogen oxides contained in the exhaust gas and desorbs them only at rising exhaust-gas temperatures, so that they can afterwards be converted by the SCR catalyst (3) which is active then. This results in an altogether improved conversion rate for the nitrogen oxides.