WO2007093325A1 - Catalyseur d'oxydation pour le traitement des gaz d'echappement et son procede de fabrication - Google Patents

Catalyseur d'oxydation pour le traitement des gaz d'echappement et son procede de fabrication Download PDF

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Publication number
WO2007093325A1
WO2007093325A1 PCT/EP2007/001117 EP2007001117W WO2007093325A1 WO 2007093325 A1 WO2007093325 A1 WO 2007093325A1 EP 2007001117 W EP2007001117 W EP 2007001117W WO 2007093325 A1 WO2007093325 A1 WO 2007093325A1
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catalyst
zeolite
palladium
oxide
platinum
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PCT/EP2007/001117
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German (de)
English (en)
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Wolfgang Strehlau
Olga Gerlach
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Hte Aktiengesellschaft The High Throughput Experimentation Company
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Publication of WO2007093325A1 publication Critical patent/WO2007093325A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/944—Simultaneously removing carbon monoxide, hydrocarbons or carbon making use of oxidation catalysts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/56—Platinum group metals
    • B01J23/62—Platinum group metals with gallium, indium, thallium, germanium, tin or lead
    • B01J23/622—Platinum group metals with gallium, indium, thallium, germanium, tin or lead with germanium, tin or lead
    • B01J23/626—Platinum group metals with gallium, indium, thallium, germanium, tin or lead with germanium, tin or lead with tin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/064—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof containing iron group metals, noble metals or copper
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/076—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof containing arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/024—Multiple impregnation or coating
    • B01J37/0242—Coating followed by impregnation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/024—Multiple impregnation or coating
    • B01J37/0244—Coatings comprising several layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/024—Multiple impregnation or coating
    • B01J37/0246—Coatings comprising a zeolite
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Definitions

  • the present invention relates to a catalyst for the simultaneous removal of carbon monoxide and hydrocarbons from oxygen-rich exhaust gases, for example from the exhaust gases of diesel engines, lean gasoline engines and stationary sources.
  • the catalyst contains a composition comprising palladium, tin oxide and a carrier oxide.
  • the catalyst contains a doping element in the form of indium, gallium, manganese or iron.
  • the catalyst may also contain a zeolite which is acted upon by active metals.
  • the invention also relates to a process for the preparation of the catalyst and a process for exhaust gas purification using the catalyst.
  • the catalyst has a high conversion performance for carbon monoxide and hydrocarbons, high thermal stability and good sulfur resistance.
  • the main pollutants from the exhaust gas of diesel engines are carbon monoxide (CO), unburned hydrocarbons (HC), such as paraffins, olefins, aldehydes, aromatics, as well as nitrogen oxides (NO x ), sulfur dioxide (SO 2 ) and soot particles, which pollute the carbon as a solid as well as in the form of the so-called "volatile organic fraction” (VOF). at a concentration which, depending on the operating point, is between approximately 1, 5 and 15%.
  • CO carbon monoxide
  • HC unburned hydrocarbons
  • NO x nitrogen oxides
  • SO 2 sulfur dioxide
  • soot particles soot particles
  • the pollutants that are emitted from lean gasoline engines, for example from directly injecting gasoline engines, consist essentially of CO, HC, NO x and SO 2 .
  • the oxygen is in stoichiometric excess over CO and HC.
  • Diesel engines and lean petrol engines are also referred to below as “lean internal combustion engines”.
  • Industrial and commercial flue gases may also contain unburned hydrocarbons and carbon monoxide.
  • oxygen-rich exhaust gas is understood to mean an exhaust gas in which the oxygen is present in stoichiometric excess relative to the oxidizable pollutants such as CO and HC.
  • oxidation catalysts are used. They have the task of removing carbon monoxide and hydrocarbons by oxidation, which ideally produces water and carbon dioxide. In addition, soot can be removed by oxidation, which also forms water and carbon dioxide.
  • EP 1 129 764 A1 discloses an oxidation catalyst comprising at least one zeolite and additionally one of the carrier oxides aluminum oxide, silicon oxide, titanium oxide and aluminum silicate and one of the noble metals Pt, Pd, Rh, Ir, Au and Ag, wherein the mean particle size of the noble metals between 1 and 6 nm.
  • the embodiments also relate exclusively to catalysts with platinum as the sole noble metal.
  • US 6,132,694 discloses a catalyst for the oxidation of volatile hydrocarbons consisting of a noble metal such as Pt, Pd, Au, Ag and Rh, and a metal oxide having more than one stable oxidation state and including at least tin oxide.
  • the metal oxide may be doped with small amounts of oxides of the transition metals. Other oxides are not mentioned.
  • the catalyst is prepared such that preferably a monolithic body is loaded with multiple layers of tin oxide. On the tin oxide, the noble metal is then applied. According to the examples, particularly good results are obtained when the noble metal is platinum and the oxide with more than one stable oxidation state is tin oxide.
  • the use of a carrier oxide is not provided.
  • the formation of NO 2 on the diesel oxidation catalyst may be desirable because the NO 2 contributes to carbon black degradation, ie, its oxidation to carbon dioxide and water.
  • Dieseloxidati- onskatalysator and soot particle filter is also referred to as CRT system (continuously regenerating trap) and is disclosed for example in the patents EP 835,684 and US 6,516,611.
  • CRT system continuously regenerating trap
  • platinum catalyzes the oxidation of the sulfur contained in the fuel to sulfur trioxide (SO3), which can lead to undesirable sulfate formation and increased soot particle emission.
  • SO3 sulfur trioxide
  • the platinum-containing catalysts Due to the chemical and physical properties of platinum, the platinum-containing catalysts show considerable weaknesses after high thermal stress.
  • the exhaust gas temperatures of high-performance diesel engines lie predominantly within a temperature range between 100 and 450 ° C. within the driving cycle relevant for the emission limit values. Driving cycles are, for example, the FTP cycle (USA) or the NEDC cycle (Europe).
  • the exhaust gas temperatures are in the range between 120 and 250 ° C.
  • temperatures reach a maximum of 650 to 700 ° C. This requires, on the one hand, low light-off temperatures (T 50 value) of the oxidation catalysts and, on the other hand, high thermal stability in order to avoid a drastic loss of activity due to aging during full-load operation.
  • Corresponding coatings can also be referred to as oxidation catalysts.
  • the soot can be burned at intervals, with the necessary Rußabbrandtemperaturen can be generated for example by internal engine measures.
  • the Rußabbrand is associated with a high heat release, which can lead to a deactivation of the applied to the filter platinum-containing oxidation catalysts.
  • platinum-containing oxidation catalysts for exhaust gases from diesel passenger cars are therefore usually equipped with very high platinum contents. They typically range from 2.1 to 4.6 g / L (60-130 g / ft 3). For example, up to 9 grams of platinum are used in a 2 liter catalyst. The use of high amounts of platinum is an important cost factor in the exhaust aftertreatment of diesel vehicles. A reduction of the platinum content in the catalyst is of great economic interest.
  • platinum catalysts are also loaded with palladium, with platinum-palladium ratios of 2: 1 or 3: 1 being set especially in applications for purifying exhaust gas from direct-injection ("DI") diesel engines
  • addition of palladium to platinum leads to a decrease in the fresh activity of the catalyst and a reduction in sulfur tolerance
  • these catalysts generally still have significantly more platinum than palladium, so that possible cost savings resulting from the substitution of Platinum by palladium, rather minor len.
  • An excess of platinum compared to the palladium is usually necessary, because only so the necessary low temperature activity can be ensured for DI diesel cars.
  • the temperature peaks produced at the diesel oxidation catalyst can be more than 800 ° C. and can lead to thermal damage to the catalyst.
  • the diesel particulate filter itself can be coated with oxidation catalyst.
  • the additional coating of the diesel particulate filter has the task of oxidizing the carbon monoxide released during the soot combustion to carbon dioxide. With high thermal stability and simultaneously high activity of such a coating, the upstream additional oxidation catalyst could be completely dispensed with in some applications.
  • Both of the oxidation catalyst functionalities discussed herein in connection with the diesel particulate filters require high thermal stability of the catalysts, with platinum-containing catalysts having disadvantages for the reasons mentioned above.
  • exhaust systems which consist of either a 3-way catalyst or an oxidation catalyst and a downstream NO x - storage catalyst.
  • the three-way catalyst or oxidation catalyst in particular has the task of minimizing the comparatively high hydrocarbon emissions which occur in homogeneous lean operation or, in particular, in stratified charge operation.
  • the thermal stability and the highest possible activity at low temperatures corresponding, mostly used close to the engine catalysts play an outstanding role.
  • the object of the invention was to develop a catalyst for the removal of pollutants from exhaust gases of lean internal combustion engines and exhaust, which can oxidize CO and HC to CO 2 and water with high activity, and at the same time an improved thermal stability compared to the catalysts of the prior art the technique has.
  • the amount of the expensive platinum element should be greatly reduced over the prior art catalysts, so that a significant saving in material costs should be made possible as compared with the prior art catalysts.
  • composition comprising palladium, tin oxide, a carrier oxide and at least one doping element
  • At least one zeolite optionally containing at least one zeolite, wherein the at least one zeolite is loaded with active metal, wherein the active metal is platinum, palladium, rhodium, ruthenium, iridium, iron, gallium or a mixture thereof.
  • carrier oxide preferably means an oxide which is thermally stable and has a high surface area.
  • carrier oxide also includes a mixture of at least two different carrier oxides.
  • titanium oxide includes all possible oxides and suboxides as well as all possible hydroxides and carbonates.
  • palladium includes both the element and compounds thereof, for example, oxides and suboxides.
  • the (i) candidate dopants are iron, manganese, indium and gallium.
  • the doping elements have a generally enhancing catalytic effect or stabilize the catalyst against deactivation.
  • the catalyst contains zeolite, it can be acted upon with active metal selected from the elements of platinum, palladium, rhodium, ruthenium, iridium, gallium or iron.
  • active metal selected from the elements of platinum, palladium, rhodium, ruthenium, iridium, gallium or iron.
  • the active metal can be present either on or in the zeolite.
  • the term "on or in the zeolite” basically leaves open whether the noble metal is present in the inner or outer structure of the zeolite, since a clear differentiation is often not possible.
  • the active metal it is possible for the active metal to migrate out of the inner structure at least partially, in particular at elevated temperature, and to deposit on the outer surface, and it is also possible for metals which are initially oxides, to introduce themselves into the inner structure of the zeolites be present on the outer surface of the zeolite, during a thermal treatment at least partially migrate into the exchange positions of the zeolite and thus be converted into the internal structure of the zeolite.
  • the active metal present on or in the zeolite promotes in particular the storage or conversion of the hydrocarbons. It can be applied to the zeolite during the preparation of the catalyst. It is also possible to use in the preparation of the catalyst zeolites, which already contain active metal.
  • One or more zeolites can be used in each case.
  • the dopants support the catalytic action of the composition consisting of palladium, tin oxide and aluminum-containing carrier oxide.
  • the doping elements used are preferably iron, manganese, indium and gallium or mixtures thereof.
  • iron include all oxides, suboxides, hydroxides, sulfates, phosphates, carbonates and cationic forms of the elements Fe, Mn, In and Ga.
  • carrier oxides are preferably oxides having a BET surface area greater than 10 m 2 / g. Particular preference is given to oxides having a BET surface area of greater than 50 m 2 / g, more preferably having a BET surface area in a range from 60 to 350 m 2 / g. Preferably, carrier oxides are used which, even after high temperature loading, have a high BET surface area. Also preferred is a carrier oxide having a low tendency to bind sulfur oxides (SO x ).
  • the carrier oxide used is aluminum-containing materials.
  • An aluminum-containing carrier oxide is to be understood as meaning a carrier oxide which comprises, in particular, aluminum oxide, silicon / aluminum mixed oxide, aluminosilicate, kaolin, modified kaolin or mixtures thereof.
  • precursor substances of aluminum oxide for example boehmites, which are converted into aluminum oxide after thermal treatment.
  • aluminum oxides doped with silicon oxide, oxides of alkaline earth elements or rare earth elements can also be used.
  • modified kaolins is understood to mean kaolins in which part of the Al 2 O 3 present in the structure has been leached out by a thermal treatment followed by an acid treatment
  • the kaolins treated in this way have a higher BET surface area and a lower aluminum content compared to the starting material
  • Corresponding modified kaolins may also be referred to as aluminosilicates and are commercially available.
  • carrier oxides suitable for the invention, to which the present invention is not limited are the following commercially available oxides:
  • Zeolites are known compounds and are sometimes commercially available.
  • modification here includes the zeolite type and the specific chemical composition, eg. As the Si / Al ratio.
  • the zeolite is usually present as starting material in the sodium form, ammonium form or in the H form. It is possible to use the sodium, ammonium or H Form by impregnation with metal salts and oxides or by ion exchange in another ionic form to convict.
  • the loading of the zeolite with active metal is to be understood not only as ion exchange, but generally as deposition of the active metal on the zeolite or zeolite.
  • active metal may preferably be present as ion, as oxide, suboxide, carbonate, sulfate, nitrate or in elemental form.
  • the loading of the zeolite with palladium can be carried out in such a way that a water-soluble palladium compound, e.g. in the form of aqueous palladium nitrate solution is brought into contact with the zeolite. After drying and optionally calcination, palladium-containing zeolite is present.
  • zeolite types Y zeolite, DAY zeolite (dealuminated Y), USY (Ultra Stabilized Y), ZSM-5, ZSM-II, ZSM-20, silicalite, ferrierite, mordenite and ⁇ -zeolite are particularly suitable.
  • the zeolites can also be hydrothermally treated.
  • hydrothermal-stable zeolites with a Si / Al ratio> 8, with higher Si / Al ratios being preferred.
  • zeolites which are suitable for the invention but to which the present invention is not limited are: Mordenite HSZ®-600 (Tosoh), Ferrierite HSZ @ -700 (Tosoh), HSZ @ -900 ( Tosoh), USY HSZ @ -300 (Tosoh), DAY Wessalith HY25 / 5 (Degussa), ZSM-5 SiO 2 / Al 2 O 3 25-30 (Grace Davison), ZSM-5 SiO 2 / Al 2 O 3 50-55 (from Grace Davison), CBV 3020E (from Zeolyst), CBV 8014 (from Zeolyst), CP 914 (from Zeolyst), ⁇ -zeolite HBEA-25 (Fa.
  • zeolites It is also possible to use several zeolites. These then preferably differ in that they have different pore radii or different Si / Al ratios or different pore radii and different Si / Al ratios.
  • zeolites have the ability to adsorb hydrocarbons at low exhaust gas temperatures and desorb them when the light-off temperature of the catalyst is reached or exceeded.
  • the mode of action of the zeolites may also be to "crack" long chain hydrocarbons found in the exhaust gas, that is to break them down into smaller fragments, which can then be more easily oxidized by the noble metal.
  • a catalytically active material which consists of a zeolite-coated fiber material, wherein the zeolite is a carrier of gold and iron-containing species.
  • the material is due a catalytic effect used to deodorize aeration in the sanitary area.
  • the particularly high activity and stability of the catalyst is caused by the special properties of the palladium / tin oxide / carrier oxide composition and by the special nature of the doping elements.
  • the mixture of at least two different zeolite types is preferred.
  • the mixture of zeolites with low polarity and slightly increased polarity is suitable for adsorbing and activating both polar and non-polar hydrocarbons.
  • the polarity can be influenced not only by the zeolite type but also by the Si / Al ratio.
  • the number of acidic centers of a zeolite and thus its polarity increase with increasing aluminum content.
  • more active metal can be introduced into the zeolite by ion exchange in cationic form as the proportion of aluminum increases.
  • an essential feature of the palladium / tin oxide / carrier oxide composition is that the tin oxide deposited on the carrier oxide has an X-rayographically amorphous or a nanoparticulate form. Surprisingly, the X-ray amorphous or nanoparticulate form of that tin oxide deposited on the carrier oxide is retained even at high loading of the carrier oxide with tin.
  • high loading refers to a content of tin to carrier oxide of about 8 to 30 wt .-% (based on elemental tin).
  • the palladium is also present in combination with the tin oxide in an X-raynographic amorphous or a nanoparticulate form on the aluminum-containing carrier oxide.
  • X-ray amorphous is intended to mean that no evaluable reflections characteristic of a substance are obtained by means of X-ray wide-angle diffraction This statement applies at least to the experimental conditions disclosed in the experimental section.
  • particle sizes can be determined from X-ray diffractograms using the Scherrer equation:
  • D is the thickness of a crystallite
  • ⁇ is the wavelength of the X-ray used
  • B is the half-width of the respective reflection
  • B is the position of the fresh catalysts, ie calcined at 500 ° C., according to the Scherrer method determined tin oxide particle sizes of about 1-100 nm, wherein the particle sizes of the tin oxide of the carrier oxide used can depend.
  • the tin oxide present on these catalysts can be described as "X-ray amorphous.”
  • X-ray amorphous After aging at 700 ° C., no or only a very small growth of the tin oxide particles is observed, depending on the carrier oxide used However, the sizes of corresponding tin oxide particles remain in the nanoparticulate dimension, that is to say with sizes of a few nm to a maximum of 100 nm, depending on the temperatures to which the catalyst is exposed, which underlines the very good durability of the catalysts according to the invention.
  • doping implies that the corresponding doping elements are used only in relatively low concentrations in relation to the oxidic matrix,
  • the oxidic matrix is to be understood as meaning the composition of carrier oxide and tin oxide.
  • the doping elements indium, gallium, manganese and iron lead to a significant stabilization of the palladium in continuous operation.
  • the palladium catalysts lose potency and effectiveness with increasing time.
  • the light-off temperatures for carbon monoxide and hydrocarbons shift over time to higher temperatures.
  • the doping elements are able to minimize the deactivation of the catalysts of the invention and to prevent altogether in favorable cases. The extent to which deactivation occurs depends, in particular, on the operating temperatures and the concentrations of carbon monoxide and hydrocarbons.
  • the preferred embodiments a) to i) of the catalyst are therefore also distinguished by the fact that a) palladium and tin oxide, and together present in the immediate topographic proximity on a carrier oxide particle, b) the tin oxide in a roentgenographically amorphous or nanoparticulate form on the carrier oxide, c) the palladium together with the tin oxide in an X-ray amorphous or a nanoparticulate form is present on the carrier oxide, d) at least one doping element selected from the elements of indium, gallium, manganese and iron is used, e) the carrier oxide according to points a) -c) is aluminum-containing, f) if necessary a hydrothermally stable zeolite is used with a silicon / aluminum ratio of> 8, g) if necessary, the hydrothermally stable with active metal consisting of platinum, palladium, rhodium, ruthenium, iridium, iron or mixtures thereof is acted upon.
  • this distribution also implies that the catalyst contains, for example, mixtures of at least two palladium-containing carrier oxides, each having different concentrations of tin oxide and / or palladium.
  • this distribution also includes that the catalyst to be applied to a honeycomb-shaped carrier body is produced by the method of gradient coating or zone coating. In a gradient coating, a gradient of the palladium is adjusted over the length of the honeycomb body. In this way, a higher concentration of palladium should be provided at the site of entry of the exhaust gas of the internal combustion engine into the catalyst in order to achieve an overall better efficiency of the palladium.
  • the catalyst is preferably used for the application as powder, granules, extrudate, shaped article or coated honeycomb body.
  • the catalyst is present as a coated molded body, preferably as a coated honeycomb body, wherein it is structured in the form of a double layer.
  • the catalyst is present as a coated molded body, wherein on the molded body, a layer of the composition consisting of palladium, tin oxide, doping element and carrier oxide is applied and on said layer, a further layer is applied, which contains zeolite, wherein active metal in the form of platinum or palladium or mixtures thereof are present on or in edm zeolites.
  • the catalyst preferably has a structure in which channels formed by macropores coexist with meso- and / or micropores.
  • the particular catalytic properties of the catalyst of the present invention are determined by the methods disclosed hereinbelow for preparing the catalyst, by the relatively high loading of the carrier oxide with promoter or by the selection of the proportions by weight of the components contained in the catalyst and the use of zeolite Doping substances achieved.
  • the catalyst is prepared by a process characterized by comprising steps (j), optionally (jj) and (jjj):
  • palladium and tin compound are meant all compounds which can be suspended in a liquid medium and / or which are completely or at least partially soluble in this medium.
  • active metal is meant the elements or oxides of platinum, palladium, rhodium, ruthenium, iridium, gallium, and iron
  • active metal refers exclusively to those precious metals which be brought into contact with the zeolite.
  • the palladium is present together with the tin on the carrier oxide and can also be present as an active metal on the zeolite.
  • Iron and gallium can be both doping element and active metal.
  • compound of a doping element all compounds which can be suspended in a liquid medium and / or which are completely or at least partially soluble in this medium.
  • Compound of an active metal and “compound of palladium” are understood to mean all compounds of platinum, rhodium, iridium, ruthenium, palladium, gallium and iron which can be suspended in a liquid medium and / or completely or in this medium at least partially soluble.
  • palladium and tin compounds and the compounds of the doping elements and active metals are used which are completely or at least partially soluble in the liquid medium.
  • the liquid medium is water.
  • salts of palladium, platinum, tin, the doping elements are used.
  • Salts are, for example, the salts of inorganic and organic acids, such as chlorides, bromides, cyanides, nitrates, oxalates, acetates or tartrates.
  • inorganic and organic acids such as chlorides, bromides, cyanides, nitrates, oxalates, acetates or tartrates.
  • complex compounds is also possible.
  • the compounds used of palladium, tin, and the doping elements and Aktiemetalle can be subjected to a chemical treatment.
  • they may be treated with acids or complexing agents, as described below for the tin compounds.
  • said compounds can be added, for example, to a particularly good solubility state, which is advantageous for the intended processing.
  • the tin compound used is preferably tin oxalate dissolved or suspended in water, it being possible to further increase the solubility by adding acids, for example nitric acid.
  • Compound of a doping element means all compounds of Ga, In Mn and Fe which can be suspended in a liquid medium and / or are completely or at least partially soluble in this medium.
  • the use of palladium nitrates is particularly advantageous.
  • the compounds of the doping elements are to be applied to the carrier oxide together with the compounds of tin present in acidic solutions, the use of compounds of the doping elements in the form of nitrates is likewise particularly advantageous.
  • a process is preferably used in which the starting compounds of palladium, tin, the doping elements and active metals are brought into contact with the carrier oxide or zeolite by means of an aqueous medium.
  • Contacting of step Q) means that compounds of the tin, the palladium and the doping elements in suspended or, preferably, dissolved form are applied either simultaneously, in mixtures or sequentially on the common carrier oxide For example, first the compounds of the tin and the doping elements can be formed The carrier oxide can be applied while the compounds of palladium are brought into contact with the carrier oxide in a subsequent step. As a rule, drying takes place after each contacting.
  • Contacting of step (jj) means that compounds of the active metals in suspended or preferably dissolved form are applied to the zeolite either simultaneously, in mixtures or sequentially, whereby the active metal is suspended or preferably dissolved on or in the zeolite
  • zeolite can be impregnated with an aqueous solution of the compounds of the corresponding active metals After drying and calcination of the impregnated zeolite, the active metals remain on or in the zeolite
  • the active metal-loaded zeolite in aqueous medium for example in the form of an aqueous
  • intermediate or final calcination can be dispensed with, and the active-metal-containing zeolite can be dispensed directly, for example in the form of a w Be processed ⁇ ßrigen suspension.
  • composition consisting of palladium, tin oxide, doping element and carrier oxide
  • first contact aqueous compounds of palladium and tin with the carrier oxide and to convert the resulting suspension into a dry powder by spray drying. This can then optionally calcined or processed directly to a washcoat. It is also possible initially to produce only a dried powder consisting of tin oxide and carrier oxide and to impregnate the compound of palladium and the doping elements only in a later process step.
  • drying and calcination can be carried out virtually in a single process step.
  • the first route of production envisages treating zeolite with an aqueous solution of the compound of the active metals and converting the corresponding suspension into a dry powder by spray-drying, spray-calcination or else by oven-drying or o-fenkalzination.
  • Preparation route 2 The second route of preparation provides zeolite in an aqueous suspension and to add the compound of the active metals.
  • the active metal can be fixed on the zeolite by sorption.
  • the sorption properties of the active metal compounds can generally be influenced by adjusting the pH in such a way that a quantitative uptake of the active metal by zeolite takes place.
  • all embodiments are preferred which have generally been proven in catalyst research, especially "washcoat” and / or “Honeycomb” and "powder or Pellef 'technologies.
  • the preparation of the catalyst is set forth below by means of a washcoat / honeycomb technology, which is particularly suitable for the production of autocatalysts.
  • the powder consisting of palladium, tin oxide, doping element and carrier oxide (according to (ii.i) is slurried in water to a suspension and ground to a washcoat suspension
  • the components of the catalyst can be applied to this. This is followed by drying and calcination.
  • the coating is characterized by a homogeneous mixing of the constituents of the catalyst used and leads to a so-called "single-layer catalyst.” If zeolite is to be used, it can be used together with the composition consisting of palladium, tin oxide, doping element and carrier oxide in aqueous It does not matter whether the zeolite contains active metal or not.
  • Binders are mixed in aqueous medium.
  • the responsive suspension can then, if still necessary, be ground and applied to the already containing the palladium, tin oxide, doping element and carrier oxide moldings. This is followed by drying and calcination.
  • the coating of the molding is characterized in this case by the The appearance of two different, inherently homogeneous layers leads to a so-called "double-layer catalyst.”
  • As a binder for the zeolite which is primarily intended to enable good adhesion of the zeolite, aluminum-containing or silicon-containing oxides are suitable.
  • Tin oxide and carrier oxide coated shaped body in a solution containing the compound of the palladium and the doping element, and impregnated. This is followed by drying again. If the catalyst does not contain any zeolites, then a calcination takes place. If the use of zeolite is desired, the active metal-containing or active metal-free zeolites in aqueous suspension, to which a binder may be added, if necessary, ground and on the already containing the palladium, tin oxide, doping element and carrier oxide shaped body be applied. This is followed by drying and calcination.
  • the coating of the molding is characterized in this case by the
  • the preparation of the catalysts according to the invention requires drying steps between the individual coating or impregnation steps. Suitable drying temperatures are generally between 60 and 500 ° C.
  • the molding is usually calcined.
  • the method also includes the step (yy):
  • the calcination step is conducted at a temperature of preferably 200 to 1000 0 C, more preferably 300 ° C to 900 0 C, in particular 400 to 800 0 C performed.
  • the calcination step thermally fixes the compounds of tin, palladium, doping elements and possibly the active metals and converts them into their catalytically active form.
  • Calcination also increases the mechanical strength of the catalyst.
  • the calcination can be carried out, for example, in dry or moist air, in nitrogen, forming gas or steam.
  • composition consisting of tin oxide, carrier oxide and doping element
  • preparation of the composition consisting of tin oxide, carrier oxide and doping element is preferably carried out by "spray drying”, “spray impregnation”. tion “and” spray calcination "produced. Also, the production medium “rotary tube drying” and “Drehrohrkalzintechnik” has proven itself. These methods are also well suited when the palladium is applied to the carrier oxide together with the tin oxide. These methods are also useful in the preparation of the active metal-containing zeolite.
  • the preparation of the catalyst can also be carried out by other known methods, for example by extrusion or extrusion.
  • the catalyst according to the invention after preparation is preferably present as a powder, granules, extrudate or as a shaped body before, for example, as a coated honeycomb body.
  • the percentages by weight in each case relate to the elemental masses of palladium, tin, the active metals and the doping elements.
  • the weights are based on the respective oxidic compounds.
  • Typical amounts of supported catalyst oxide palladium catalyst according to the present invention are 0.53 g / L-2.1 g / L (15-60 g / ft 3 ), but may vary from these amounts depending on the application.
  • g / ft 3 refers to supported catalysts as is familiar to those skilled in the art on the elemental mass of precious metal in relation to the volume of the carrier, for example to the volume of a honeycomb carrier body.
  • the total amount of tin is 3 - 50 wt .-% (calculated as element) based on the carrier oxide, wherein a total amount of 5 - 30 wt .-%, more preferably 5 - 15 wt .-% is preferred.
  • the total amount of palladium (calculated as element) based on the carrier oxide is preferably 0.2-10% by weight. More preferred is a total amount of 0.4 to 5 wt%.
  • the weight ratio of tin to palladium is preferably in a range of 2: 1 to 50: 1, with a weight ratio in a range of 4: 1 to 30: 1 being more preferred.
  • the weight ratio of tin to the total amount of doping elements is preferably in a range of 10: 0.01 to 10: 4, with a weight ratio in a range of 10: 2 to 10: 0.2 being more preferable.
  • the total amount of zeolite based on the carrier oxide is preferably 3-60% by weight. More preferably, a total amount of zeolite is in a range of 8-50 wt%. Particularly preferred is a range of 10 to 35 wt .-%.
  • the total amount of active metal (calculated as element) to the total amount of zeolite (calculated as oxide) is preferably 0.001 - 10 wt .-%. Stronger is a total amount of 0.1 - 8 wt .-%. Particularly preferred is a range of 0.5-5 wt .-%.
  • the total amount of dopant elements (calculated as element) to carrier oxide is preferably 0.01-10 wt%, more preferably 0.02-8 wt%, more preferably 0.03-5 wt%.
  • the invention also relates to the use of the catalyst for the removal of pollutants from exhaust gases of lean internal combustion engines and exhaust.
  • the present invention also relates to a method for exhaust gas purification of lean internal combustion engines and venting using the catalyst disclosed above.
  • the method of exhaust gas purification is carried out such that the exhaust gas purification comprises the simultaneous oxidation of hydrocarbons and carbon monoxide and the removal of soot by oxidation.
  • the catalyst can also be operated in combination with at least one further catalyst or soot particle filter.
  • the soot particle filter are coated with the catalyst.
  • the combination of the catalyst with a further catalyst comprises
  • the soot particle filter itself is coated with the oxidation catalyst.
  • An important aspect of the invention relates to the sequential arrangement of a platinum-based catalyst with the palladium catalyst according to the invention. It is crucial that the platinum-based catalyst is connected upstream of the palladium catalyst, so it is upstream of this, that is, the emitted exhaust gas flows first over the platinum-based catalyst and then over the palladium catalyst. Surprisingly, in particular, this arrangement shows a very high durability without the palladium catalyst gradually deactivated in continuous operation. In addition, the palladium catalyst is protected against so-called "fouling processes.” Such fouling includes, for example, the deposition or formation of hard-to-oxidize carbon compounds which are formed from the hydrocarbons present in the exhaust gas and only at high levels of palladium catalysts. often occurring during normal driving, temperatures can be oxidized.
  • the combination of platinum-based catalyst and the palladium catalyst according to the invention does not reduce the added value of the present invention, since the total costs of palladium- and platinum-based catalyst are still substantially lower than if only a platinum-based catalyst of the state of the art were used. Technique are used. This is attributed to the fact that only a small platinum-based catalyst is used, ie a portion of the Pd catalyst according to the invention is quasi substituted by the platinum-based catalyst and thus the total cost of platinum and palladium are still significantly lower than for the amount of platinum, the required by the prior art.
  • a corresponding zone coating can be carried out in such a way that the honeycomb substrate is first dipped to a predefined depth in the suspensions and, if appropriate, impregnation solutions required for the preparation of the platinum-based catalyst In later steps, the substrate is rotated and submerged to a predefined depth in the suspensions and optionally impregnating solutions required for the preparation of the catalyst according to the invention
  • the order of the coating plays no role here.
  • platinum-based catalysts e.g. Commercially available diesel oxidation catalysts in question.
  • platinum-based catalyst also includes the aforementioned platinum / palladium oxidation catalysts of the prior art.
  • the catalyst according to the invention in particular in combination with a platinum-based catalyst, is very stable thermally. After high temperature hydrothermal aging, it exhibits an improved effect for CO and HC oxidation compared to prior art catalysts.
  • the platinum-based catalyst contains at least one zeolite for the efficient storage of hydrocarbons.
  • platinum-based catalyst The optimal dimensioning of platinum-based catalyst to the inventive Pd catalyst depends strongly on the raw emissions of the engine, in particular from the hydrocarbon emissions. In general, the platinum-based catalyst should have about 25-90% of the volume of the Pd catalyst. Thus, if the volume of the Pd catalyst, for example as a Honeycomb preparation, is 1 liter, then the upstream platinum-based catalyst should also have a volume of about 0.25 to 0.9 liters as a honeycomb finish.
  • the noble metal loading of the platinum-based catalyst also depends on the raw emissions of the engine. Suitable platinum loadings for modern DI engines are about 5 to 150 g / ft 3 platinum.
  • Another object of the invention is therefore also a device which is characterized in that it comprises a catalyst according to the invention as described above and a Pt-based catalyst as described above, wherein the Pt-based catalyst is upstream of the catalyst according to the invention.
  • Heating rate 15 ° C / minute
  • Exhaust gas composition 1500 vppm CO, 200 vppm Cj (decane), 100 vppm Ci (toluene), 140 vppm Ci (propene), 100 vppm NO, 13% O 2 , 5% CO 2 , 5% H 2 O, balance - N 2 .
  • honeycomb-shaped catalysts had a diameter of 2.54 cm and a length of 2.54 cm
  • VBOl ⁇ 3.1 g / L platinum (90 g / ft 3 ) * - for year 2005 diesel vehicles
  • HC reduction For the evaluation of the catalysts of the T, 50 - (temperature is reached at which 50% conversion) of CO oxidation as well as the integral HC reduction from 100 to 220 0 C, which is called nt to as HC j used.
  • HC reduction it should be noted that the hydrocarbons are first adsorbed only at the catalyst at lower temperatures and only oxidized to CO 2 and H 2 O at higher temperatures.
  • the term HC reduction thus includes the adsorption and oxidation of hydrocarbons.
  • the hydrothermal aging was carried out in a muffle furnace at a temperature of 850 0 C in an air stream containing 10% water. The catalysts were held at this temperature for 16 hours and then cooled to room temperature.
  • Example B04 The catalyst of Example B04 was scaled up and measured on an engine test bench. The test was carried out on a 1.9 L TDI engine from the company Volkswagen. The new European driving cycle was applied and passed through 3 times for reproduction.

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Abstract

L'invention concerne un catalyseur caractérisé en ce qu'il contient une composition qui présente du palladium, de l'oxyde d'étain, un élément de dopage et un oxyde de support et éventuellement une zéolithe, ainsi qu'un procédé pour sa fabrication, son utilisation pour éliminer les substances nocives de moteurs à combustion interne travaillant en conditions pauvres et évacuer l'air et, ainsi qu'un procédé d'élimination des substances nocives de gaz d'échappement de moteurs à combustion interne travaillant en conditions pauvres par recours au catalyseur, par oxydation du monoxyde de carbone et des hydrocarbures tout en éliminant les particules de suie par oxydation, et un procédé d'utilisation du catalyseur selon l'invention disposé à la suite d'un catalyseur à base de platine, le catalyseur à base de platine étant placé en amont du catalyseur selon l'invention.
PCT/EP2007/001117 2006-02-15 2007-02-09 Catalyseur d'oxydation pour le traitement des gaz d'echappement et son procede de fabrication WO2007093325A1 (fr)

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WO2008022967A1 (fr) * 2006-08-19 2008-02-28 Umicore Ag & Co. Kg filtre à particules diesel revêtu catalytiquement, procédé pour sa fabrication et utilisation du filtre
US8449852B1 (en) 2011-12-01 2013-05-28 Basf Corporation Diesel oxidation catalysts, systems and methods of treatment
CN103889554A (zh) * 2011-10-27 2014-06-25 庄信万丰股份有限公司 用于制备二氧化铈-氧化锆-氧化铝复合氧化物的方法及其应用
US8980209B2 (en) 2012-12-12 2015-03-17 Basf Corporation Catalyst compositions, catalytic articles, systems and processes using protected molecular sieves
US9034287B2 (en) 2013-03-13 2015-05-19 Basf Corporation Catalyst compositions, articles, methods and systems
US9321042B2 (en) 2012-12-12 2016-04-26 Basf Corporation Catalyst compositions, catalytic articles, systems and processes using large particle molecular sieves
CN108479784A (zh) * 2018-04-04 2018-09-04 清华大学 一种双载体臭氧催化剂和模块化催化氧化废水处理装置
CN115155576A (zh) * 2022-07-22 2022-10-11 山东亮剑环保新材料有限公司 一种整体式金属基材贵金属催化模块的制备方法

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EP2070581A1 (fr) * 2007-12-10 2009-06-17 HTE Aktiengesellschaft The High Throughput Experimentation Company Catalyseur d'oxydation contenant du Pt et du Pd
DE102008041530A1 (de) 2008-08-25 2010-03-04 Dirk Dombrowski Verfahren und Abgasanlage zur Reinigung SOx-haltiger Abgase, insbesondere von Schiffsbrennkraftmaschinen

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EP0811419A2 (fr) * 1996-06-07 1997-12-10 Toyota Jidosha Kabushiki Kaisha Dispositif catalytique pour purifier des gaz d'échappement d'un moteur diesel
WO2000028196A1 (fr) * 1998-11-06 2000-05-18 Ceryx Incorporated Appareil integre permettant d'extraire des polluants d'un courant de fluide dans un environnement a melange pauvre avec recuperation de chaleur
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Publication number Priority date Publication date Assignee Title
WO2008022967A1 (fr) * 2006-08-19 2008-02-28 Umicore Ag & Co. Kg filtre à particules diesel revêtu catalytiquement, procédé pour sa fabrication et utilisation du filtre
US7922987B2 (en) 2006-08-19 2011-04-12 Umicore Ag & Co. Kg Catalytically coated diesel particle filter, process for producing it and its use
CN103889554A (zh) * 2011-10-27 2014-06-25 庄信万丰股份有限公司 用于制备二氧化铈-氧化锆-氧化铝复合氧化物的方法及其应用
US8449852B1 (en) 2011-12-01 2013-05-28 Basf Corporation Diesel oxidation catalysts, systems and methods of treatment
US8980209B2 (en) 2012-12-12 2015-03-17 Basf Corporation Catalyst compositions, catalytic articles, systems and processes using protected molecular sieves
US9321042B2 (en) 2012-12-12 2016-04-26 Basf Corporation Catalyst compositions, catalytic articles, systems and processes using large particle molecular sieves
US9034287B2 (en) 2013-03-13 2015-05-19 Basf Corporation Catalyst compositions, articles, methods and systems
CN108479784A (zh) * 2018-04-04 2018-09-04 清华大学 一种双载体臭氧催化剂和模块化催化氧化废水处理装置
CN108479784B (zh) * 2018-04-04 2023-09-19 清华大学 一种双载体臭氧催化剂和模块化催化氧化废水处理装置
CN115155576A (zh) * 2022-07-22 2022-10-11 山东亮剑环保新材料有限公司 一种整体式金属基材贵金属催化模块的制备方法

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