摘要:
A catalytically active diesel particulate filter with ammonia trap action is presented, which, in addition to an oxidation-active coating (2), comprises a coating (1) which is catalytically active in the SCR reaction. By means of this inventive diesel particulate filter, it is possible to make exhaust gas aftertreatment systems for removing nitrogen oxides and particulates from the exhaust gas of lean engines considerably simpler and less expensive.
摘要:
An exhaust gas purification system (method and device) for the treatment of diesel exhaust gases containing nitrogen oxides and hydrocarbons is disclosed, which comprises the addition of ammonia or of a compound decomposable to ammonia into the exhaust gas stream and the subsequent leading of the exhaust gas stream over two successively arranged SCR catalysts with different properties and compositions. Both SCR catalysts are free of vanadium compounds and only the downstream SCR catalyst contains zeolite compounds. The exhaust gas purification system according to the invention is characterized by good “kick-off” behavior at low temperatures and a simultaneously high conversion performance over a wide temperature range.
摘要:
An exhaust gas purification system (method and device) for the treatment of diesel exhaust gases containing nitrogen oxides and hydrocarbons is disclosed, which comprises the addition of ammonia or of a compound decomposable to ammonia into the exhaust gas stream and the subsequent leading of the exhaust gas stream over two successively arranged SCR catalysts with different properties and compositions. Both SCR catalysts are free of vanadium compounds and only the downstream SCR catalyst contains zeolite compounds. The exhaust gas purification system according to the invention is characterized by good “kick-off” behavior at low temperatures and a simultaneously high conversion performance over a wide temperature range.
摘要:
A catalytically active diesel particulate filter with ammonia trap action is presented, which, in addition to an oxidation-active coating (2), comprises a coating (1) which is catalytically active in the SCR reaction. By means of this inventive diesel particulate filter, it is possible to make exhaust gas aftertreatment systems for removing nitrogen oxides and particulates from the exhaust gas of lean engines considerably simpler and less expensive.
摘要:
The reductive removal of nitrogen oxides from the exhaust gas from internal combustion engines operated predominantly under lean conditionstakes place in a selective catalytic reduction (SCR) of the nitrogen oxides by means of ammonia or a compound which can be decomposed into ammonia as reducing agent. Conventional SCR catalysts typically have a relatively narrow working temperature window, usually 350° C. to 520° C., in which good nitrogen oxide conversions can be achieved with sufficient selectivity. SCR catalyst formulations whose working window is in the temperature range from 150° C. to 350° C. generally not be used at higher temperatures since they oxidize the ammonia required as reducing 18 agent to nitrogen oxides at above 350° C. To cover the entire exhaust gas temperature range typical of vehicles having been operating internal combustion enginesextending from 200° C. to 600° C., it has therefore mostly been necessary to use complicated exhaust gas systemscontaining a plurality of catalysts having different working temperature ranges. Disclosed is a structured SCR catalyst whose working range extends over a significantly broader temperature window and by means of which complicated exhaust gas units can be considerably simplified, with a saving of components.
摘要:
The reductive removal of nitrogen oxides from the exhaust gas from internal combustion engines operated predominantly under lean conditions takes place in a selective catalytic reduction (SCR) of the nitrogen oxides by means of ammonia or a compound which can be decomposed into ammonia as reducing agent. Conventional SCR catalysts typically have a relatively narrow working temperature window, usually 350° C. to 520° C., in which good nitrogen oxide conversions can be achieved with sufficient selectivity. SCR catalyst formulations whose working window is in the temperature range from 150° C. to 350° C. generally not be used at higher temperatures since they oxidize the ammonia required as reducing 18 agent to nitrogen oxides at above 350° C. To cover the entire exhaust gas temperature range typical of vehicles having been operating internal combustion engines extending from 200° C. to 600° C., it has therefore mostly been necessary to use complicated exhaust gas systems containing a plurality of catalysts having different working temperature ranges. Disclosed is a structured SCR catalyst whose working range extends over a significantly broader temperature window and by means of which complicated exhaust gas units can be considerably simplified, with a saving of components.
摘要:
In exhaust gas purification units for decreasing nitrogen oxides in lean-burn exhaust gas of internal combustion engines by selective catalytic reduction by means of ammonia, introduction of excess ammonia leads to undesirable emissions of unused ammonia. These emissions can be decreased by means of ammonia barrier catalysts. In the ideal case, ammonia is oxidized to nitrogen and water by these catalysts. These require additional space in the exhaust gas purification unit which may have to be taken away from the space provided for the SCR main catalyst. In addition, the use of such ammonia barrier catalysts can result in overoxidation of the ammonia to nitrogen oxides.To overcome these disadvantages, a catalyst containing two superposed layers is proposed for the removal of nitrogen-containing pollutant gases from diesel exhaust gas. The lower layer contains an oxidation catalyst and the upper layer can store at least 20 milliliters of ammonia per gram of catalyst material. This catalyst displays reduced ammonia breakthrough at good SCR conversions in the low-temperature range. It can be used as SCR catalyst having reduced ammonia breakthrough or as ammonia barrier catalyst.
摘要:
To equip a diesel particle filter with a zeolite-containing coating uniformly over the entire length of the particle filter and with a further zeolite-free coating which is applied, from the entry side of the filter, solely up to a specific length of the filter, it is proposed, first, to apply the zeolite-free coating from the entry side of the filter and only thereafter to apply the zeolite-containing coating over the entire length of the filter from the exit side of the filter. As a result of this sequence of coatings, a better adhesive strength of the coatings than when both coatings are applied from the entry side is ensured.
摘要:
The invention relates to a special device for the purification of diesel exhaust gases, which device comprises, in the flow direction of the exhaust gas, an oxidation catalyst, a diesel particle filter with catalytically active coating, and, downstream of a device for introducing a reducing agent from an external reducing agent source, an SCR catalyst. The oxidation catalyst and the catalytically active coating of the diesel particle filter contain palladium and platinum. The ratio of the noble metals platinum and palladium in the overall system and on the individual components, oxidation catalyst and catalytically coated diesel particle filter, are coordinated with one another in such a way as to obtain firstly an optimum NO/NO2 ratio in the exhaust gas upstream of the downstream SCR catalyst, and secondly optimum heating and HC conversion behaviour during an active particle filter regeneration.
摘要翻译:本发明涉及一种用于净化柴油机废气的专用装置,该装置在排气的流动方向上包括氧化催化剂,具有催化活性涂层的柴油颗粒过滤器,以及用于引入 还原剂来自外部还原剂源,SCR催化剂。 柴油颗粒过滤器的氧化催化剂和催化活性涂层含有钯和铂。 整个系统中的贵金属铂和钯与单个组分,氧化催化剂和催化涂层柴油颗粒过滤器的比例彼此协调,以便首先获得排气中最佳的NO / NO 2比例 下游SCR催化剂上游的气体,其次是活性颗粒过滤器再生过程中的最佳加热和HC转化行为。
摘要:
The invention relates to a special device for the purification of diesel exhaust gases, which device comprises, in the flow direction of the exhaust gas, an oxidation catalyst, a diesel particle filter with catalytically active coating, and, downstream of a device for introducing a reducing agent from an external reducing agent source, an SCR catalyst. The oxidation catalyst and the catalytically active coating of the diesel particle filter contain palladium and platinum. The ratio of the noble metals platinum and palladium in the overall system and on the individual components, oxidation catalyst and catalytically coated diesel particle filter, are coordinated with one another in such a way as to obtain firstly an optimum NO/NO2 ratio in the exhaust gas upstream of the downstream SCR catalyst, and secondly optimum heating and HC conversion behaviour during an active particle filter regeneration.
摘要翻译:本发明涉及一种用于净化柴油机废气的专用装置,该装置在排气的流动方向上包括氧化催化剂,具有催化活性涂层的柴油颗粒过滤器,以及用于引入 还原剂来自外部还原剂源,SCR催化剂。 柴油颗粒过滤器的氧化催化剂和催化活性涂层含有钯和铂。 整个系统中的贵金属铂和钯与单个组分,氧化催化剂和催化涂层柴油颗粒过滤器的比例彼此协调,以便首先获得排气中最佳的NO / NO 2比例 下游SCR催化剂上游的气体,其次是活性颗粒过滤器再生过程中的最佳加热和HC转化行为。