摘要:
A batch process for preparing a zeolitic material having framework type CHA and a framework structure comprising Si, Al, O, and H, comprising (i) providing a seeding material comprising a zeolitic material having framework type CHA and a framework structure comprising Si, Al, O, and H; (ii) preparing a mixture comprising a source of Si, a source of Al, a seeding material provided in (i), a CHA framework structure directing agent comprising a cycloalkylammonium compound, and water, wherein the cycloalkylammonium compound is a compound comprising a cation R 1 R 2 R 3 R 4 N + wherein R 1 , R 2 , R 3 are, independently from one another, an alkyl residue having from 1 to 6 carbon atoms, and R 4 is a 5- to 8-membered cycloalkyl residue, wherein in mixture, the molar ratio of water relative to Si comprised in the source of Si and in the seeding material, calculated as SiO 2 , is in the range of from 5:1 to 15:1, wherein the mixture, the molar ratio of sodium, calculated as Na 2 O, relative to Si comprised in the source of Si and in the seeding material, calculated as SiO 2 , is in the range of from 0:1 to 0.1:1; (iii) heating the mixture prepared in (ii) in its liquid state to a temperature of the mixture in the range of from 50 to 90 °C and keeping the liquid mixture at a temperature in this range for 5 to 100 h; (iv) heating the heated mixture of (iii) to a temperature of the mixture in the range of from 190 to 230 °C in a crystallization vessel and keeping the mixture at a temperature in this range under autogenous pressure in the crystallization vessel for 0.5 to 10 h, obtaining a solid material comprising a zeolitic material having framework type CHA and a framework structure comprising Si, Al, O, and H, suspended in its mother liquor.
摘要:
A method for the direct synthesis of a crystalline material with the AEI zeolithic structure containing iron-species and being essentially free of alkali ions, comprising the following steps: (i) preparation of a mixture containing water, a high-silica zeolite as a main source of silica and alumina, an alkyl-substituted cyclic ammonium cation as organic structure directing agent (OSDA), a source of iron, and a source of an alkali metal ion [Alk], to obtain a final synthesis mixture having the following molar composition: SiO 2 : a AI 2 O 3 : b Fe : c OSDA : d Alk : e H 2 O wherein a is in the range from 0.001 to 0.2; wherein b is in the range from 0.001 to 0.2; wherein c is in the range from 0.01 to 2; wherein d is in the range from 0.001 to 2; wherein e is in the range from 1 to 200; (ii) crystallization of the mixture achieved in (i); (iii) recovery of the crystalline material achieved in (ii); (iv) calcination of the crystalline material from step (iii); and (v) removal of the alkali metal cation, present in the calcined crystalline material after step (iv) to obtain a final molar composition: SiO 2 : o AI 2 O 3 : p Fe : q Alk wherein o is in the range from 0.001 to 0.2, p is in the range from 0.001 to 0.2 and q is below 0.02.
摘要:
A catalytic article for treating an exhaust gas stream containing one or more of NOx, hydrocarbons, CO, SOx and ammonia from a combustion turbine comprises (a) a substrate having an inlet end and an outlet end defining an axial length; (b) an oxidation layer comprising an oxidation catalyst comprising one or more noble metals, the oxidation layer being positioned on the substrate and covering the axial length of the substrate; and (c) an SCR layer comprising an SCR catalyst, the SCR layer being positioned on the oxidation layer and overlapping a portion of the oxidation layer, wherein the portion is less than 100%.
摘要:
A catalytic filter is provided having a mixture of an SCR catalyst and soot oxidation catalyst where the soot oxidation catalyst is a copper doped ceria, iron doped ceria or manganese doped ceria. The mixture of an SCR catalyst and soot oxidation catalyst provides for a lowering of the peak oxidation temperature for soot removal from the filter. The use of the filter allows for improved soot combustion and reduces the susceptibility of an SCR catalyst contained on a filter to deterioration. The soot oxidation catalyst also improves the resistance of the SCR catalyst to poisoning and subsequent deterioration of SCR performance.
摘要:
Described are catalysts effective to abate NO x , hydrocarbons, and carbon monoxide from a gasoline engine exhaust gas. Such catalysts include a substrate having a first and second material disposed thereon, the first material effective to catalyze selective catalytic reduction of nitrogen oxides in the presence of ammonia and the second material effective to abate hydrocarbons and carbon monoxide, the first material comprising a molecular sieve promoted with copper and/or iron in a low loading, the second material comprising at least one oxide of Ni, Fe, Mn, Co, and Cu on a support selected from oxides of Ce, Ce-Zr, Zr, Mn, Pr and combinations thereof. Also described are gasoline engine exhaust gas treatment systems and methods of treating exhaust gas from a gasoline engine.
摘要:
Catalysts having a blend of platinum on a support with low ammonia storage with an 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.
摘要:
A catalyst article having an extruded support having a plurality of channels through which exhaust gas flows during operation of an engine, and a single layer coating or a bi-layer coating on the support, where the extruded support contains a third SCR catalyst, the single layer coating and the bilayer-coating contain platinum on a support with low ammonia storage and a first SCR catalyst. 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.
摘要:
An oxidation catalyst for treating an exhaust gas produced by a compression ignition engine comprising: a substrate having an inlet end surface and an outlet end surface; a catalytic material disposed on the substrate, wherein the catalytic material comprises platinum (Pt); and a capture material, wherein the capture material is disposed on the outlet end surface.
摘要:
Described is a selective catalytic reduction catalyst comprising a zeolitic framework material of silicon and aluminum atoms, wherein a fraction of the silicon atoms are isomorphously substituted with a tetravalent metal. The catalyst can include a promoter metal such that the catalyst effectively promotes the reaction of ammonia with nitrogen oxides to form nitrogen and H 2 0 selectively over a temperature range of 150 to 650 °C. In another aspect, described is a selective catalytic reduction composite comprising an SCR catalyst material and an ammonia storage material comprising a transition metal having an oxidation state of IV. The SCR catalyst material promotes the reaction of ammonia with nitrogen oxides to form nitrogen and H 2 0 selectively over a temperature range of 150 °C to 600 °C, and the SCR catalyst material is effective to store ammonia at temperatures of 400 °C and above. A method for selectively reducing nitrogen oxides, and a method for simultaneously selectively reducing nitrogen oxide and storing ammonia are also described. Additionally, an exhaust gas treatment system is also described.
摘要翻译:描述了包含硅和铝原子的沸石骨架材料的选择性催化还原催化剂,其中一部分硅原子被四价金属同晶取代。 催化剂可以包括促进剂金属,使得催化剂有效地促进氨与氮氧化物的反应,以在150至650℃的温度范围内选择性地形成氮和H 2 O. 另一方面,描述了包含SCR催化剂材料和包含具有IV氧化态的过渡金属的氨储存材料的选择性催化还原复合材料。 SCR催化剂材料促进氨与氮氧化物的反应,在150℃至600℃的温度范围内选择性地形成氮和H 2 O,并且SCR催化剂材料在400℃及以上的温度下有效储存氨。 还描述了选择性还原氮氧化物的方法,以及同时选择性还原氮氧化物和储存氨的方法。 此外,还描述了废气处理系统。
摘要:
Described is a selective catalytic reduction material comprising a spherical particle including an agglomeration of crystals of a molecular sieve. The catalyst is a crystalline material that is effective to catalyze the selective catalytic reduction of nitrogen oxides in the presence of a reductant at temperatures between 200 °C and 600 °C. A method for selectively reducing nitrogen oxides and an exhaust gas treatment system are also described.