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    • 专利摘要:
    CATALYST SOOT FILTER, EXHAUST SYSTEM FOR A DIESEL ENGINE, AND METHOD FOR INCREASING THE% OF THE NO2 / NOX REASON IN A DIESEL EXHAUST GAS. Catalytic soot filter for a diesel engine to increase the percentage of NOx of total NOx in the exhaust gas leaving the catalytic soot filter compared to the percentage of NO2 of total NOx in the exhaust gas leaving the catalytic soot filter comprises a substrate of wall flow comprising an inlet end, an outlet end, an axial length of substrate extending between the inlet end and the outlet end, and a plurality of channels defined by the inner walls of the wall flow substrate, in that the plurality of channels comprises a plurality of input channels having an open input end and a closed output end and a plurality of output channels having a closed input end and an open output end, wherein the wall surfaces internal channels of the plurality of input channels comprise a reactive coating composition of at least one composition that of the inlet coating comprising at least one oxide of (...).
    公开号:BR112015009514B1
    申请号:R112015009514-3
    申请日:2013-10-31
    公开日:2021-01-12
    发明作者:Gavin Michael Brown；Andrew Francis Chiffey；David MARVELL
    申请人:Johnson Matthey Public Limited Company；
    IPC主号:
    专利说明:

    [001] The present invention relates to a catalyzed soot filter to treat diesel engine exhaust emissions that removes particulate matter (PM), hydrocarbons (HC) and carbon monoxide (CO) from the exhaust emissions and simultaneously enriches the concentration of nitrogen dioxide (NO2) in nitrogen oxides (NOx) emitted from diesel engines to allow a more efficient treatment of such nitrogen oxides.
    [002] Vehicle emissions that are the main pollutants that have negative effects on public health and the natural environment are generally recognized as being carbon monoxide, hydrocarbons, nitrogen oxides (NOx) and particulate matter.
    [003] Diesel engines work with a high air to fuel ratio under very poor fuel conditions. Because of this, they have low levels of gas phase and carbon monoxide hydrocarbon emissions and are instead characterized by relatively high levels of NOx and particulate matter emissions, in relation to the current and future emission regulations agreed by intergovernmental organizations. . Controlling particulate matter and NOx emissions poses significant challenges for the diesel engine manufacturer because they are coupled inversely. Modern passenger vehicles include exhaust gas recirculation. When the engine runs cooler it produces less NOx, but more particulate matter and conversely at higher temperatures the combustion is more complete, generating less particulate matter, but more NOx. For this reason, changes in the engine design need to be combined with trapping processes and effective treatment to limit emissions of these harmful pollutants into the atmosphere.
    [004] The emission legislation in Europe of 1 September 2014 (Euro 6) maintains the admissible limit specified in Euro 5 (which came into force in September 2009 for vehicle approval and applied since January 2011 for registration and sales of new car types) for the 4.5 mg / km mass of particulate matter emitted from diesel passenger cars as measured by the particulate measurement program procedure.
    [005] However, for Euro 6, all vehicles equipped with a diesel engine will be substantially obliged to reduce their emissions of nitrogen oxides as soon as Euro 6 enters into force. For example, passenger car emissions will be tolerated up to 80 mg / km which is a reduction of more than 50% compared to Euro 5 standards. In addition, combined emissions of hydrocarbons and nitrogen oxides from diesel vehicles also will be reduced. For example, these will be tolerated up to 170 mg / km for passenger cars.
    [006] For this reason, the new Euro 6 emission standard presents several challenging design problems to satisfy diesel emission standards. In particular, how to design a filter, or an exhaust system including a filter, to reduce emissions of NOx and NOx and combined hydrocarbons, while still meeting the emission standards for PM and CO pollutants all with an acceptable back pressure, for example, as measured by the maximum back pressure in the EU steering cycle.
    [007] Ambient particulate matter is typically divided into the following categories based on its aerodynamic diameter (aerodynamic diameter is defined as the diameter of a sphere with a density of 1 g / cm3 with the same settling speed in the air as the measured particle ): (i) Particles with an aerodynamic diameter less than 10 μm (PM-10); (ii) Fine particles with a diameter below 2.5 μm (PM-2.5); (iii) Ultrafine particles with a diameter below 100 nm; and (iv) Nanoparticles with a diameter below 50 nm.
    [008] Since the mid-1990s, particle size distributions of particles depleted from internal combustion engines have received increased attention due to possible adverse affects on the health of fine and ultrafine particles. The concentrations of PM-10 particulates in ambient air are regulated by law in the USA. A new, additional ambient air quality standard for PM-2.5 was introduced in the USA in 1997 as a result of health studies that indicated a strong correlation between human mortality and the concentration of fine particles below 2.5 μm.
    [009] Interest has now shifted to considering ultrathin and nanoparticles generated by diesel and gasoline engines because they have been found to penetrate more deeply into the lungs of humans than larger particulates and, consequently, are believed to be more harmful than larger particles. This belief is extrapolated from the findings of studies on particulates in the range of 2.5 to 10.0 μm.
    [0010] Diesel particle size distributions have a well-established bimodal character that correspond to the mechanisms of nucleation and particle agglomeration, with the corresponding types of particles referred to as the core mode and the accumulation mode respectively.
    [0011] In the core mode, the diesel particulate is composed of numerous small particles maintaining very little mass. Almost all core mode diesel particulates are significantly smaller than 1 μm in size, that is, they comprise a mixture of fines, ultrafines and nanoparticles. Core mode particles are believed to be composed mostly of volatile condensates (hydrocarbons, sulfuric acid, nitric acid etc.) and contain little solid material, such as ash and carbon.
    [0012] Particles in the accumulation mode have been found to comprise solids (carbon, metallic ash, etc.) intermixed with condensates and adsorbed material (heavy hydrocarbons, sulfur species, nitrogen oxide derivatives, etc.). Coarse-mode particles are believed to be generated in the diesel combustion process and can be formed through mechanisms such as deposition and subsequent entrainment of particulate matter from the walls of an engine cylinder, exhaust system, or from the gas sampling system. particulate.
    [0013] The composition of the nucleation particles can change with the operating conditions of the engine, environmental condition (particularly temperature and humidity), dilution conditions and sampling system. Laboratory work and theory showed that most of the formation and growth in the core mode occurs in the low dilution ratio range. In this range, the conversion of gas into particles from the precursors of volatile particles, such as heavy hydrocarbons and sulfuric acid, leads to the nucleation and simultaneous growth of the core mode and adsorption on the existing particles in the accumulation mode. Laboratory tests (see, for example, SAE 980525 and SAE 2001-01-0201) have shown that formation in the core mode increases strongly with decreasing air dilution temperature, but there is conflicting evidence as to whether humidity has an influence.
    [0014] Generally, low temperature, low dilution ratios, high humidity and long residence times favor the formation and growth of nanoparticles. Studies have shown that nanoparticles consist mainly of volatile material such as heavy hydrocarbons and sulfuric acid with evidence of solid fraction only at very high loads.
    [0015] The particulate collection of diesel particulates in a diesel particulate filter is based on the principle of separation of the particulates transported by the gas from the gas phase using a porous barrier. Diesel particulate filters can be defined as deep bed filters and / or surface type filters. In deep bed filters, the average pore size of the filter medium is greater than the average diameter of the collected particles. The particles are deposited on the medium through a combination of deep filtration mechanisms, including diffusion deposition (Brownian motion), inert deposition (impaction) and flow line interception (Brownian motion or inertia).
    [0016] In surface type filters, the diameter of the pore in the middle of the filter is smaller than the diameter of the particulate matter, thus, the particulate matter is separated by sieving. The separation is made by an accumulation of the collected particulate matter itself, an accumulation that is commonly referred to as "Vqrtc fg finvtc>" q "g q rtqeguuq eqoq" hinvtc> "q f g Vqrtc"
    [0017] It is understood that diesel particulate filters, such as ceramic wall flow monoliths, can work through a combination of deep and surface filtration: a filter cake develops at higher soot loads when the Deep filtration is saturated and a layer of particulate begins to cover the filtration surface. Deep filtration is characterized by an almost lower efficiency and lower pressure drop than that of cake filtration.
    [0018] Diesel particulate filters have been shown to be extremely effective in removing particulate matter over the entire particle size range. However, these filters have limited capacity to trap particulate matter before the pressure drop becomes excessive, so it is necessary to periodically regenerate the diesel particulate filter. Passive regeneration does not happen quickly as the combustion of particulate matter retained in the presence of oxygen requires temperatures higher than those typically provided by the exhaust from the diesel engine. An effective method for lowering the combustion temperature of the particulate matter trapped in the diesel particulate filter is the addition of a reactive coating composition to the filter wall. Compositions of catalyzed reactive coating compositions used are similar to those used in diesel oxidation catalysts and typically comprise at least one metal of the platinum group. The reactions in the catalyzed diesel particulate filter include the oxidation of CO and HC and the oxidation of NO to NO2 which allows the combustion of the particulate matter at a much lower temperature than in the presence of oxygen.
    [0019] WO 2006/031600 describes a catalyzed soot filter that simultaneously treats the gaseous components of CO and HC and the particulate matter in the diesel exhaust gas. The catalyzed soot filter comprises: a wall flow substrate comprising an inlet end, an outlet end, an axial length of substrate extending between the inlet end and the outlet end, and a plurality of passages defined by the walls internal wall flow substrate; wherein the plurality of passages comprises inlet passages having an open inlet end and a closed outlet end, and outlet passages having a closed inlet end and an open outlet end; wherein the inner walls of the inlet passages comprise a first inlet liner extending from the inlet end to a first inlet liner end, thereby defining a first inlet liner length, in which the first inlet liner length is less than the axial length of the substrate; wherein the inner walls of the outlet passageways comprise an outlet liner that extends from the outlet end to an outlet liner end, thereby defining an outlet liner length, where the outlet liner length is less than the axial length of the substrate; wherein the sum of the first inlet liner and outlet liner lengths is substantially equal to the axial length of the substrate; wherein the first inlet lining length defines an upstream zone and the outgoing lining length defines a downstream zone; wherein the first inlet liner comprises at least one first platinum group metal inlet component; and, in which at least 50% of the metal components of the platinum group are present in the downstream zones. In the embodiments, both the inlet and outlet coatings of the catalyzed soot filter contain refractory metal oxide, for example, alumina, as a support for the metal components of the platinum group. The refractory metal oxide supports used in the inlet and outlet coatings are ground so that 95% of the particles have a diameter of <5 micrometers and preferably <3 micrometers. The wall flow substrates have a porosity of 60% and an average pore diameter of about 15 to 25 micrometers. It is also described that the coatings can be arranged as a thin coating on the surface of the inner walls of the wall flow substrate and / or can permeate the porous walls to some extent. However, there is no description of any coating method for obtaining the described CSFs.
    [0020] WO 00/29726 describes a CSF soot filter # 6 based on a Corning cordierite wall flow substrate of dimensions 11.25 inches in diameter x 14.0 inches in length and having a cell density of 100 cells per square inch. The CSF # 6 soot filter was catalyzed with 178.5 g / m3 (5.0 g / ft3) Pt, 17,850 g / m3 (500 g / ft3) CeO2 and 5,355 g / m3 (150 g / ft3) ZrO2, These components were applied to the soot filter substrate via solution impregnation with soluble precursors. In addition, a reactive coating composition slurry was applied to one end of the soot filter substrate to a depth (length) of about 4 inches inside one face of the substrate. This reactive coating composition was comprised of 12.4% by weight Pt on gamma-alumina and was deposited on one end of the filter substrate to result in a Pt load of 2,163.42 g / m3 (60.6 g / ft3 ) equivalents. Thus, the total Pt load on the CSF was 2,341.92 g / m3 (65.6 g / ft3).
    [0021] A variety of technologies have been explored to reduce the NOx emitted from diesel exhaust systems to environmentally acceptable nitrogen for release into the atmosphere. The selective reduction of NOx (poor NOx catalyst) using diesel fuel or a derivative to selectively catalyze the oxidation of HC and NOx to CO2, H2O and N2 has been investigated extensively and two main candidate materials identified as selective catalysts. However, it has been reported in the literature that it is thought that these systems will not be sufficient to satisfy the severe requirements of Euro 6.
    [0022] Poor NOx collectors (also known as NOx adsorbent catalysts) use a base metal oxide to adsorb NOx during the poor mode of operation. The NO-rich exhaust gas is converted to NO2 over a catalyst containing metal of the platinum group and the NO2 is trapped and stored, for example, over an alkali metal oxide which is incorporated into the catalyst containing metal of the platinum group. NO2 is then desorbed under rich conditions and using rhodium which is also incorporated on the catalyst.
    [0023] SCR involves the use of ammonia in the presence of an appropriate catalyst, ammonia that acts as a selective NOx reducer. Typically urea is the source of ammonia, which hydrolyzes in the exhaust system at about 200 ° C. Suitable catalysts include metal-exchanged zeolites and mixed catalysts of vanadium and titanium dioxide. The technology is potentially capable of a NOx reduction greater than 90%, thus it is seen as a good candidate to meet the new stringent requirements for NOx for diesel engines. However, SCR is prone to contamination of HC, CO and particulates that reduce its effectiveness. In addition, for many diesel engines, most of the NOx emitted from the exhaust system is in the form of NO, while a faster reaction of SCR proceeds from a mixture of NO and NO2. NO2 is a more reactive compound than NO and the faster SCR reaction can extend the operating temperature of the SCR process to lower temperatures. However, NO2 reduction occurs per se more slowly than NO per se. Consequently, particularly a mixture of 1: 1 NO: NO2, NO: NO2 is more desirable for efficient NOx reduction.
    [0024] WO 02/14657 describes an aftertreatment system for low-burn diesel applications configured with a catalyzed soot filter downstream of an SCR to produce substantially better NOx conversion performance than the SCR catalyst alone. The catalyzed soot filter is coated on the inner walls of the filter substrate with the catalyst being applied by impregnating the solution. This application technique suggests that the catalyst is substantially present within the inner walls of the substrate to minimize the increase in exhaust gas back pressure caused by the catalyst as much as possible. The catalyst is coated along the entire length of both the inner walls of the inlet channel and the inner walls of the outlet channel of the filter substrate. It is mentioned on page 31, lines 28-29 that it may be possible to selectively coat portions of the channels, but no other example is provided.
    [0025] GB 2481057 A describes a method of treating NOx nitrogen oxides and PM particulate matter comprising the steps of catalytically converting NO nitrogen monoxide to NO2 nitrogen dioxide using a catalyst composition comprising a manganese oxide and at least one metal from the platinum group, converting NOx to nitrogen N2, by contacting a mixture of NO and NO2 with a nitrogen reducing agent in the presence of a SCR catalyst for selective catalytic reduction, and the filtration of PM to burn it into NO2. An exhaust system is also claimed comprising a catalyzed CSF soot filter with a portion of its substrate being catalyzed and having an SCR downstream of it, where the catalyst on the substrate comprises a manganese oxide and at least one platinum group metal. . Where an SCR catalyst is disposed on a substrate downstream of the CSF, the exit zone of the CSF is less than 45% of the total axial length of the filter substrate.
    [0026] Applicants have now designed a new catalyzed soot filter to treat diesel engine exhaust emissions that removes PM, HC and CO from exhaust emissions and simultaneously enriches the NO2 concentration in the NOx emitted from a diesel engine to allow for a more efficient treatment of NOx downstream, for example, using an SCR catalyst. The catalyzed soot filter is based on a wall flow substrate and is designed so that at least the catalyst in the downstream channels is substantially coated on, not within, the inner walls of the filter substrate, with axial coating lengths different inlet and outlet channels, an arrangement that has been found to maintain an acceptable exhaust gas back pressure in relation to the coating charge and soot trapping, and regeneration and has also been found to provide increased NO2 enrichment compared to filters with subsVcpekcnogpVg coatings qw rctekcnogpVg “fgpVtq fc pcrgfg”. Vcku like those catalyzed filters of the prior art discussed above.
    [0027] According to a first aspect the invention provides a catalyzed soot filter for a diesel engine to increase the percentage of NO2 of total NOx in the exhaust gas leaving the catalyzed soot filter in relation to the percentage of NO2 of total NOx in exhaust gas entering the catalyzed soot filter, a filter comprising a wall flow substrate comprising an inlet end, an outlet end, an axial length of substrate extending between the inlet end and the outlet end, and a plurality of channels defined by the inner walls of the wall flow substrate, wherein the plurality of channels comprises a plurality of input channels having an open input end and a closed output end and a plurality of output channels having an end of closed inlet and an open outlet end, in which the inner wall surfaces of the plurality of inlet channels comp they comprise a reactive coating composition of at least one inlet coating composition comprising at least one refractory metal oxide, a stabilized rare earth metal oxide or a mixture of at least one refractory metal oxide and one earth metal oxide optionally stabilized rare and at least one catalytically active metal selected from the group consisting of platinum, palladium, iridium, rhodium, silver, gold and mixtures of any two or more of them, in which at least one inlet coating composition extends over an axial inlet lining length from the open inlet end to a downstream inlet lining end, where the axial inlet lining length is less than the axial length of the substrate, where the outer surfaces of the inner walls of the plurality of outlet channels comprise a reactive coating composition of at least one coating composition the outlet over the wall comprising at least one refractory metal oxide, an optionally stabilized rare earth metal oxide or a mixture of at least one refractory metal oxide and an optionally stabilized rare earth oxide and at least one metal catalytically active selected from the group consisting of platinum, palladium, iridium, rhodium, silver, gold and mixtures of any two or more of them, in which at least one outlet coating composition on the wall has an average particle size (D50 ) of between 4 and 15 μm, such as 7 to 12 μm, or 8 to 10 μm, and extending over an axial outlet lining length from a downstream outlet end to an open outlet end, where the axial outlet liner length is 55 to 90% of the substrate axial length and the axial outlet liner length is greater than the axial inlet liner length.
    [0028] Methods for coating wall flow filter substrates according to the invention include those described in WO 99/47260 by the applicants, that is, a method for coating a monolithic support, comprising the steps of (a) fixing a medium of containment on top of a support, (b) dosing a predetermined amount of a liquid component within said containment means, or in order (a), then (b) or (b) then (a), and ( c) by applying pressure or vacuum, removing said liquid component from at least a portion of the support, and retaining substantially all of said amount within the support; and WO 2011/080525, i.e., a method of coating a honeycomb substrate monolith comprising a plurality of channels with a liquid comprising a catalyst component, a method comprising the steps of: (i) maintaining the substrate monolith substantially vertically; (ii) introducing a predetermined volume of the liquid into the substrate via open ends of the channels at a lower end of the substrate; (iii) retaining sealably the liquid introduced into the substrate; (iv) inverting the substrate containing the retained liquid; and (v) applying a vacuum to the open ends of the substrate channels at the lower, inverted end of the substrate to remove the liquid along the substrate channels.
    [0029] The location of the reactive coating composition on a substrate monolith can be influenced by several factors. Such a factor is the water content of the reactive coating composition. Very generally, the higher the solids content in the reactive coating composition, the less carrier medium is available to transport the solids and the reactive coating composition is more likely to be coated linearly, that is, on and along the wall surface. of the substrate monolith, than to be moved laterally, that is, within a porous wall.
    [0030] For similar reasons, the selection of a porosity for the substrate monolith can also influence the location of the reactive coating composition. Generally, and for a given reactive coating composition, the greater the porosity of the substrate monolith, the more spaces there are for the liquid carrier to pass through, so the liquid carrier can be removed from the solids in the reactive coating composition more easily and the solids can is preferentially located on the wall surface.
    [0031] The availability of a carrier medium in a reactive coating composition to transport the solids of the reactive coating composition within a porous wall can also be influenced by rheology modifiers. Rheology modifiers, that is, thickeners such as xanthan gum, influence how mobile a carrier medium is during coating. A relatively more viscous reactive coating composition, the viscosity of which has been increased by the addition of a rheology modifier, is more likely to remain on a substrate monolith surface wall, because the carrier medium is preferably bonded within the reactive coating composition and less available to transport component solids within a porous wall.
    [0032] The location of the reactive coating composition solids can also be influenced by the particle size of the reactive coating composition as expressed by the average particle size (by volume) (also known as D50) or D90 (the particle size) below which are 90% of the particles in the reactive coating composition): generally for a given filter having a porosity “x” g wo Vcocpjq fg rqtq ofifkq “{”. swcnVq ognqt q Vcocpjq fg rcttiewnc of the reactive coating composition it is more likely that the solids of the reactive coating composition can be transported within the porous wall.
    [0033] The selection of the filter properties can also influence the location. As mentioned above, the decrease in porosity generally predisposes the coating on the wall instead of inside the wall. Thus, as mentioned above, for a reactive coating composition tgnfq wo fcfq tgqt fg u „nkfqu“ c ”. wo tcocnjq fg rcttiewnc ofifkq xqnwofittkeq “d”. wo F; 2 xqnwofittkeq “e” g woc tgqnqikc “f”. rgnq cwogntq fq tcocnjq fg rqtq ofifkq fq oqn „nktq fg uwduttcto, it is likely that the reactive coating composition will enter into their porous wall.
    [0034] “F72” qw “F; 2” qw tgfetênekcu ukoüatgu cq tcocnjq fg particle of a particulate reactive coating composition here are Laser Diffraction Particle Size Analyzes using a Malvern Mastersizer 2000, which is a technique based on volume (ie D50 and D90 can also be referred to as DV50 and DV90 (or D (v, 0.50) and D (v, 0.90)) and a Mie mathematical theory model is applied to determine a distribution diluted samples of the reactive coating composition should be prepared by sonication in distilled water without surfactant for 30 seconds at 35 watts.
    [0035] The inner wall surfaces of the outlet channels comprise at least one outlet liner composition on the wall extending from the outlet end to an outlet liner end where the axial outlet liner length is less than than the axial length of the substrate. "FgpVtq fc rctgfg" swgt say that the coating composition substantially coats the surface of the inner wall and substantially does not penetrate the pores of the inner wall. In addition to the above discussion, methods of producing porous filter substrates on the wall include introducing a polymer into the porous structure, applying a reactive coating composition to the substrate and polymer followed by drying and calcining the coated substrate to burn the polymer. The methods also include controlling the particle size of the reactive coating composition so that they are close to or are larger than the pore size of the substrate. Such methods include grinding and particle size agglomeration through the addition of chemical additives. Consequently, in the embodiments, the load D50 of the reactive coating composition of at least one incoming coating composition is between 4 and 15 μm, such as 5 to 12 μm, or 7 to 10 μm. In other embodiments, a D90 particle size of at least one outlet coating composition on the wall is> 15 μm such as 18 to 40 μm, for example, 20 to 35 μm, or 25 to 30 μm. In certain embodiments, the D50 particle size is 5 μm and the corresponding D90 is about 15 μm. In another embodiment, where the D50 particle size is 7-10 μm, for example, 7-8 μm, the D90 particle size is about 20 μm.
    [0036] The length of the axial outlet lining is less than the axial length of the substrate and is 55 to 90% of the axial length of the substrate, more preferably 60 to 85% of the axial length of the substrate. The axial inlet liner length is greater than the axial inlet liner length. For example, the axial inlet liner length may be 10% longer than the axial inlet liner length when expressed as a percentage of the total axial length of the substrate. In the embodiments, the length of the axial inlet liner and the length of the axial outlet liner together are equal to the length of the axial substrate.
    [0037] The at least one outlet coating composition on the wall comprises at least one catalytically active metal as a catalyst. The at least one catalytically active metal is selected from the group consisting of platinum, palladium, iridium, rhodium, silver, gold and mixtures of any two or more of them and is more preferably platinum, palladium or a mixture thereof. Especially preferred are mixtures of platinum and palladium because palladium prevents or reduces the sintering of platinum. In order to promote the oxidation of NO to NO2 to thereby increase the NO2: NOx ratio, weight ratios rich in PT, Pt: Pd are highly preferred, such as 20: 1 to 1: 1, optionally 15: 1 to 2 : 1, with 10: 1 to 4: 1 more mentioned.
    [0038] At least one catalytically active metal can be present in the outlet wall with a concentration of 35.7 to 5,355 g / m3 (1 to 150 g / ft3), more preferably from 178,5 to 3,570 g / m3 ( 5 to 100 g / ft3). The at least one inlet coating composition may comprise a refractory metal oxide, which can be selected from the group consisting of alumina, silica, silica-alumina, alumina silicates, alumina-zirconia, alumina-chromia, titania, titania- silica, titania-zirconia and titania-alumina. Concentrations of such refractory metal oxides can be in the range of 3.049 to 60.98 kg / m3 (0.05 to 1.0 g / in3), more preferably 6.098 to 48.78 kg / m3 (0.1 to 0 , 8 g / in3). Refractory metal oxides for use in the present invention can have BET surface areas of at least 20, for example, at least 50 m2 / g.
    [0039] In the embodiments, at least one entry coating composition may comprise an optionally stabilized rare earth metal oxide selected from a cerium, praseodymium, lanthanum, neodymium and samarium oxide. Cerium oxides are especially preferred. Preferred rare earth metal oxide stabilizers include zirconium. Concentrations of such rare earth metal oxides, if present, are in the range of 1,785 to 35,700 g / m3 (50 to 1,000 g / ft3), more preferably from 3,570 to 21,420 g / m3 (100 to 600 g / ft3). If present, such rare earth metal oxides for use in the present invention can have BET surface areas of at least 20, for example, at least 50 m2 / g.
    [0040] In a separate embodiment, the at least one inlet coating composition may comprise a combination of at least one refractory metal oxide and an optionally stabilized rare earth metal oxide.
    [0041] The at least one outlet coating composition on the wall is preferably present with a reactive coating composition charge of 6.098 to 121.96 kg / m3 (0.1 to 2.0 g / in3), more preferably 12.19 to 60.98 kg / m3 (0.2 to 1.0 g / in3).
    [0042] In the embodiments, a thickness of at least one outlet coating composition on the wall is 5 to 80 μm, preferably 10 to 50 μm.
    [0043] In the embodiments, the at least one entry cladding composition may be at least one entry cladding composition on the wall over the outer surfaces of the inner walls of the plurality of entry channels; or at least one coating composition within the wall.
    [0044] In embodiments where the at least one inlet liner composition is at least one inlet liner composition on the wall of the outer surfaces of the inner walls of the plurality of inlet channels, the at least one inlet liner composition on the wall it can have an average particle size (D50) of between 4 and 15 μm, such as 5 to 12 μm, or 7 to 10 μm. In the embodiments, at least one outlet coating composition on the wall has a D90 particle size of> 15 μm, such as 18 to 40 μm, for example, 20 to 35 μm, or 25 to 30 μm. In certain embodiments, the D50 particle size is 5 μm and the corresponding D90 is about 15 μm. In another embodiment, where the D50 particle size is 7 to 10 μm, for example, 7 to 8 μm, the D90 particle size is about 20 μm.
    [0045] Alternatively, in the embodiments in which the at least one inlet coating composition is at least one in-wall coating composition, the at least one inward-facing coating composition has an average particle size (D50) of 1 to 3 μm. In such embodiments, the at least one entry coating composition within the wall has a D90 particle size of 4 to 6 µm.
    [0046] The axial inlet coating length is less than, both the axial substrate length and the axial outlet coating length. Preferably the axial inlet lining length is 10 to 45% of the axial length of the substrate, more preferably 15 to 40% of the axial length of the substrate. In the embodiments, the length of the axial inlet coating is 10 to 30% of the axial length of the substrate.
    [0047] The at least one inlet coating composition comprises at least one catalytically active metal. The at least one catalytically active metal is selected from the group consisting of platinum, palladium, iridium, rhodium, gold, silver and mixtures of any two or more of them. The at least one catalytically active metal is more preferably platinum, palladium or more preferably a mixture of both platinum and palladium. The presence of palladium can reduce the sintering of the platinum component. According to the invention, it is less important for the inlet coating composition to oxidize NO to NO2 because the inlet coating composition is designed for this purpose. Consequently, catalyst compositions that contribute to soot combustion are preferred for the inlet coating composition, for example, compositions comprising an optionally stabilized rare earth metal oxide, such as zirconium stabilized cerium oxide, although some NO2 generated in the input coating composition can be reduced back to NO after passively burning the soot trapped in the input channels (NO2 - "E" s "PQ" - "EQ + 0" Pq "however, catalyst compositions that contribute to the oxidation of NO in the inlet coating composition can reduce a Pt: Pd weight ratio in the inlet coating composition. Consequently, appropriate Pt: Pd weight ratios for the inlet coating compositions are less than for the coating compositions. input, such as a Pt: Pd weight ratio of 20: 1 to 1:10, such as 15: 1 to 1: 2, more preferably 10: 1 to 2: 1.
    [0048] The at least one catalytically active metal can be present on the entrance wall at a concentration of 35.7 to 1785 g / m3 (1 to 150 g / ft3), more preferably from 178.5 to 3,750 g / m3 (5 to 100 g / ft3).
    [0049] The at least one inlet coating composition may comprise a refractory metal oxide selected from the group consisting of alumina, silica, silica-alumina, alumina silicates, alumina-zirconia, alumina-chromia, titania, titania-silica , titania-zirconia and titania-alumina. The concentrations of such refractory metal oxides, if present, are in the range of 3.049 to 60.98 kg / m3 (0.05 to 1.0 g / in3), more preferably 6.098 to 48.78 kg / m3 (0 , 1 to 0.8 g / in3). If present, such refractory metal oxides have BET surface areas of at least 20 m2 / g, for example, at least 50 m2 / g.
    [0050] In an alternative embodiment, the at least one entry coating composition may comprise an optionally stabilized rare earth metal oxide selected from a cerium, praseodymium, lanthanum, neodymium and samarium oxide. Cerium oxides are especially preferred. Preferred rare earth metal oxide stabilizers include zirconium. The concentrations of such rare earth metal oxides, if present, can be in the range of 1,785 to 35,700 g / m3 (50 to 1,000 g / ft3), more preferably from 3,750 to 21,420 g / m3 (100 to 600 g / ft3) ) and they have a BET surface area of at least 20 m2 / g, for example, at least 50 m2 / g.
    [0051] In a separate embodiment, at least one inlet coating composition may comprise a combination of both at least one refractory metal oxide and an optionally stabilized rare earth metal oxide.
    [0052] The at least one entry coating composition on the wall is preferably present with a reactive coating composition charge of 6.098 to 121.96 kg / m3 (0.1 to 2.0 g / in3), more preferably 12.19 to 60.98 kg / m3 (0.2 to 1.0 g / in3).
    [0053] In one embodiment, the coating composition on the entry wall comprises the same ingredients as the coating composition on the exit wall. In one scenario these same ingredients are present with the same concentration in each coating composition.
    [0054] In all embodiments, the porosity of the surface of the reactive coating composition can be increased by including voids there. “Xczio” swgt fizgt a space that exists in the layer defined by the solid reactive coating composition material. The voids can include any opening, fine pore, tunnel state, crevice and can be introduced into a reactive coating composition composition to coat a porous substrate over a porous substrate by calcining a coated porous filter substrate, for example. example, cotton or chopped materials to give rise to pores produced by the formation of gas on decomposition or combustion. The average void of the reactive coating composition can be 5 to 80% with the average void diameter of 0.1 to 1,000 μm. The inclusion of voids is used to compensate for any increase in back pressure as the liner is over the wall.
    [0055] Wall flow substrates for use in the present invention are preferably composed of ceramic materials or of the ceramic or refractory metal type. Examples of ceramic or ceramic-type materials include cordierite. "G-alumina, silicon carbide, silicon nitride, zirconia, mullite, spodumene, silica-magnesia alumina or zirconium silicate. Examples of refractory metals include stainless steel. Most preferably the wall flow substrate is composed of ceramic or ceramic type materials especially cordierite and silicon carbide.
    [0056] The wall flow substrate is a porous substrate that has pores on the surface of a medium pore size. The average pore size can be determined by mercury porosimetry. The average pore size is 4 to 40 μm, for example, 6 to 35 μm, 7 to 30 μm, or 9 to 25 μm. Porosity is a measure of the percentage of empty space in a porous substrate and is related to back pressure in an exhaust system: generally, the lower the porosity, the greater the back pressure. The ceramic or ceramic-type materials of the invention have a porosity of 35 to 75%, preferably 38 to 70%, especially 40 to 65%.
    [0057] The wall flow substrate has a plurality of thin, substantially parallel gas flow channels extending along the substrate's longitudinal axis. Each channel is blocked at one end of the substrate with alternating channels blocked at opposite ends of the substrate. The wall flow substrate can contain up to 500 channels (cells) per square inch (cpsi) (1 in2 = 6.45 cm2) in cross section. Preferably the substrate is 150 to 400 cpsi (1 in2 = 6.45 cm2) in cross-section which can be rectangular, square, circular, oval, triangular or hexagonal. Preferably the cross section is square. The substrate can have a wall thickness of 6 to 22 mil (thousandths of an inch), preferably 8 to 18 mil.
    [0058] NOx exhaust gases exiting the catalyzed soot filter have an increased percentage of NO2 as compared to NOx gases entering the catalyzed soot filter. The NO2: NO ratio entering the catalyzed soot filter is typically between 5:95 to 40:60 for exhaust emissions from a diesel engine. The NO2: NO ratio leaving the catalyzed soot filter is increased over that entering the inlet and is preferably between 10:90 to 90:10, such as 30:70 to 70:30, more preferably 40:60 to 60: 40. This is because a 1: 1 NO2: NO ratio is preferred to promote the rapid NOx reduction reactions described above.
    [0059] Without wishing to be limited by theory, it is believed that the careful choice and positioning of the inlet liner and the liner on the outlet wall means that substantially all of the soot / PM emitted from the diesel engine is trapped by both the flow substrate on the entrance wall as well as on the entrance cladding on the wall. The catalytic coating composition on the intake wall oxidizes some of the NO that is emitted from the diesel engine to NO2. Passive filter regeneration occurs in the presence of NO2. During the regeneration process the particulate matter is oxidized and NO2 is converted back to NO. This NO and any residual NO2 passes through the porous substrate and through the outlet wall covering where some of the NO is oxidized to NO2. There is negligible PM in the outlet wall, so this NO2 is not required for any other passive regeneration and passes through the outlet wall with the residual NO. Consequently, NOx leaving the system has a higher percentage of NO2 than entering the system. The coating compositions also oxidize the small amounts of CO and HC emitted from the exhaust. CO and HC are preferably oxidized before NO. Consequently, by using a higher weight ratio of Pt: Pd for the inlet coating composition to that of the inlet coating composition, NO oxidation occurs more efficiently, because much less HC, CO and PM are present in the leakage present in the outlet channels of the catalyzed soot filter. The promotion of NO oxidation activity with higher weight ratios of Pt: Pd over the input coating composition is a less efficient use of expensive precious metals like platinum and palladium.
    [0060] As discussed earlier, SCR involves the use of ammonia in the presence of an appropriate catalyst that acts as a selective reducer for NOx. SCR as a treatment is prone to contamination of HC, CO and PM which reduces its effectiveness. Often the majority of NOx emitted from the exhaust system is NO although it has previously been shown that rapid reaction kinetics for the SCR reaction are for a combination of NO and NO2 in a 50:50 ratio. NO2 is the most reactive compound of NOx and consequently its presence can extend the operating temperature of the SCR to lower temperatures.
    [0061] The treatment of diesel engine emissions by the catalytic soot filter of the invention can result in the removal of PM, HC and CO and the conversion of some of the NO in the NOx emitted from the engine into NO2. For this reason, the exhaust gas emitted from the catalytic soot filter can promote the SCR reaction to thereby reduce NOx and satisfy the more stringent NOx emission regulations of Euro 6.
    [0062] According to a second aspect, the invention provides an exhaust system for a diesel engine comprising the catalytic soot filter of the invention and a selective catalytic reduction catalyst disposed downstream of the catalyzed soot filter.
    [0063] Ammonia is typically used as the reducing agent in the SCR reaction. The exhaust system according to the second aspect preferably comprises means, when in use, for introducing a precursor of the reducing agent into the exhaust gas upstream of the SCR catalyst. For example, urea water is used as a precursor to the reducing agent and can be sprayed into the exhaust gas upstream of an SCR catalyst via a nozzle. It is then thermally or hydrolytically reduced to release ammonia. In a preferred embodiment, the means for introducing a reducing agent precursor into the exhaust gas upstream of the SCR catalyst includes an ammonia source, such as a urea tank.
    [0064] In a preferred embodiment, the SCR catalyst is coated on a flow-through substrate. Overflow substrates for use with the SCR catalyst in the present invention are preferably composed of ceramic or ceramic-type materials or refractory metals. Examples of ceramic or ceramic-type materials include cordierite, g-alumina, silicon carbide, silicon nitride, zirconia, mullite, spodumene, silica-magnesia alumina or zirconium silicate. Examples of refractory metals include stainless steel. More preferably, the flow-through substrate is composed of ceramic or ceramic-type materials especially cordierite and silicon carbide.
    The flow through substrate is a flow through monolith preferably having an alveolar structure with a plurality of small, parallel thin-walled channels passing axially through the substrate and extending through the substrate, i.e., from an inlet end open to an open outlet end. The cross section of the substrate channel can be of any shape, but is preferably square, sinusoidal, triangular, rectangular, hexagonal, trapezoidal, circular or oval.
    [0066] The SCR catalyst is preferably comprised of titanium dioxide, vanadium pentoxide, tunguistic trioxide, molybdenum trioxide, silicon dioxide, zeolite, zeolite in combination with, for example, ion exchanged with a base metal component such as Fe or preferably Cu, and combinations thereof. A particularly preferred SCR catalyst comprises a CHA zeolite exchanged with copper.
    [0067] The composition of the SCR catalyst can be coated in a concentration of at least 30.49 kg / m3 (0.5 g / in3) and preferably from 60.98 to 182.94 kg / m3 (1.0 to 3 , 0 g / in3).
    [0068] The SCR catalyst selectively reduces and purges the NOx contained in the exhaust gas and transforms it into nitrogen and water, which has less impact on the environment.
    [0069] In another embodiment of the exhaust system according to the present invention, an oxidation catalyst is disposed downstream of the SCR catalyst to ensure that any ammonia slip ceqpVg> Co Eqo “c jwucpVg” qu tgswgtgpVgu swgtgo fkzgt swg q ecVcnkucft Oxidation is coated on the outlet edge of the flow-through substrate of the SCR catalyst, or that the oxidation catalyst is coated on a substrate monolith separate from the SCR catalyst.
    [0070] In an alternative embodiment the second aspect of the present invention provides an emission treatment system for a diesel engine comprising a catalytic soot filter of the invention and a poor NOx collector catalyst (LNT) disposed downstream of the catalytic soot filter .
    [0071] A typical LNT catalyst is coated on a flow-through monolith substrate. The LNT catalyst typically includes a NOx adsorbent, usually an alkaline earth metal oxide, for the storage / trapping of NOx and an oxidation / reduction catalyst. The oxidation / reduction catalyst generally comprises one or more noble metals, preferably platinum, palladium and / or rhodium. Typically, platinum is included to perform the oxidation function and rhodium is included to perform the reduction function.
    [0072] In another embodiment of the invention a diesel oxidation catalyst (DOC) is disposed downstream of the catalytic soot filter of the first aspect of the present invention.
    [0073] The DOC composition typically comprises at least one platinum group metal dispersed over a refractory metal oxide, a reducible metal oxide or any combination of two or more of them as a support. Such DOC is formed on a ceramic or metallic substrate monolith on which one or more catalyst coating compositions can be deposited, if in a zone arrangement, that is, a first zone upstream of a first DOC catalyst composition ; and a second, downstream zone of a second DOC catalyst composition; or a layered arrangement.
    [0074] In this modality the DOC is able to oxidize NO, present in the NOx emitted from the diesel engine, to NO2 before the exhaust emissions enter the catalyzed soot filter. For this reason, in this embodiment, the inlet coating length can be substantially reduced in the catalytic soot filter, for example, to 10 to 30% of the substrate's axial coating length.
    [0075] According to another aspect, the invention provides a method of increasing the% of the NO2 / NOx ratio in a diesel exhaust gas comprising NOx for downstream processes, a method which comprises contacting the exhaust gas with a filter soot catalysed according to the first aspect of the present invention or an exhaust system according to the second aspect of the present invention.
    [0076] In a preferred embodiment, the downstream process comprises the selective catalytic reduction of nitrogen oxides using an SCR catalyst and a nitrogen reducer.
    [0077] In order for the invention to be more fully understood, the following modalities and Examples will now be described only as a means of illustration and with reference to the accompanying drawings, in which: Figure 1 is a graph showing the percentage of NO2 in the NOx emitted from a catalytic soot filter of the invention (where most of the catalyst coating composition is on the outlet wall) and to a comparative catalytic soot filter (where most of the catalyst coating is on the inlet wall) over time as the soot load on the catalytic soot filter is increased; Figure 2 is a graph showing the percentage of NO2 in the NOx emitted from a catalytic soot filter (CSF) according to the invention, where the catalyst coating composition is on the wall and for a comparative catalytic soot filter in which the catalyst composition is within the wall, in which in both cases there is a DOC coated on a separate monolithic substrate disposed downstream of the catalytic soot filter; and Figure 3 shows a schematic drawing of the exhaust system according to the present invention.
    [0078] Referring to Figure 3, an exhaust system 40 for a diesel engine according to the present invention is shown comprising a catalyzed soot filter according to the present invention 8 having a coating on the Pt / Pd inlet channel which extends axially over 35% of the axial length of the total substrate from the ends of the open input channel and an axial output channel liner of the same Pt / Pd liner as the input channels extend 65% of the open outlet channel ends. Downstream of the outlet end of the catalyzed soot filter, that is, to inject a nitrogenous reducer (represented by as ammonia, ie NH3), for example, an urea precursor to ammonia, into the exhaust gas downstream of a catalyst SCR 6. The SCR 6 catalyst is an SCR CuCHA catalyst, which is coated on a through-flow substrate monolith. An outlet surface of the throughflow substrate monolith comprising the SCR catalyst may comprise a catalyst to oxidize NH3 that slides past the SCR catalyst to N2, such as 107.1 g / m3 (3 g / ft3) of a Pt catalyst / alumina disposed in a layer below the CuCHA catalyst. The exhaust gas emitted from one end downstream of the SCR overflow substrate monolith is exhausted to the atmosphere in the exhaust pipe 5. EXAMPLES Example 1
    [0079] A catalytic soot filter according to the invention was prepared by coating a 5.66 inch (14.38 cm) diameter by 8 inch (20.32 cm) long silicon carbide wall flow substrate having 300 cells per square inch (cpsi) (1 in2 = 6.45 cm2), 58% porosity and pore size of 22 μm. Using established CSF coating techniques, 80% of the coating was applied over 80% of the substrate axial length of the outlet end of the channels and 20% of the coating was about 20% of the axial length of the substrate of the input end of the channels. Prohibited. The coating slurry comprised of platinum and palladium in a 10: 1 weight ratio supported on an alumina carrier. The filter was then aged in the oven in air at 750 ° C for 5 hours.
    [0080] Platinum / palladium is present in a concentration of 357 g / m3 (10 g / ft3) and the coating composition on the wall has a reactive coating composition charge of 33.53 kg / m3 (0.55 g / in3) for both input and output, with a D50 less than or equal to 10 μm. Example 2
    [0081] A comparative catalyzed soot filter was prepared by coating the same wall flow substrate as used in Example 1 with the same coating as described in Example 1, except that 80% of the coating was applied over 80% of the axial length of the substrate of the entrance channels of the entrance ends of the same and 20% of the coating were applied over 20% of the axial length of the substrate of the exit end of the exit channels. Example 3
    [0082] Both catalytic soot filters of Example 1 and Example 2 were exposed to exhaust emissions from a 2.0 liter turbocharged diesel bench engine using 50 ppm sulfur diesel fuel working with a repeated transient cycle over a period of ten hours, with a maximum temperature in the catalyzed soot filter of about 310 to 315 ° C.
    [0083] Figure 1 shows the percentage of NO2 in the NOx emitted from the catalytic soot filters of Example 1 and Example 2. It is clear from the results shown for Example 1 that when the coating composition is present mainly on the outlet wall there is a higher percentage of NO2 in NOx coming out of the catalyzed soot filter. In addition, the percentage of NO2 coming out of the catalyzed soot filter is much more stable than when the coating composition is present mainly on the inlet wall.
    [0084] Figure 1 clearly shows that the diesel exhaust gas leaving the catalytic soot filter of the invention has the preferred NO2 / NO composition of the total NOx for the effective treatment of NOx emissions, for example, by an SCR catalyst downstream. Example 4
    [0085] A soot filter catalyzed according to the invention was prepared by coating a flow substrate on a silicon carbide wall with a volume of 3.0 liters having 300 cpsi (1 in2 = 6.45 cm2), 42% porosity and a pore size of 14 μm with platinum / palladium in a 10: 1 weight ratio supported on the alumina coating composition. The filter was then aged in the oven in air at 750 ° C for 10 hours.
    [0086] Platinum / palladium are present in a concentration of 1,785 g / m3 (50 g / ft3) in 30% of the axial length of the inlet channel walls of the inlet end with a reactive coating composition load of 21, 34 kg / m3 (0.35 g / in3) and a D50 of between 7 and 8 μm. The outlet channel walls are coated over 70% of their axial length from the outlet end with the platinum / palladium coating composition at a concentration of 1,785 g / m3 (50 g / ft3) with a composition load of reactive coating of 12.19 kg / m3 (0.20 g / in3), with a D50 of between 7 and 8 μm. Example 5
    [0087] A diesel oxidation catalyst was prepared by coating a 4.66 inch (11.84 cm) diameter by 5.7 inch (14.48 cm) long ceramic flow through substrate with platinum / palladium in a ratio by weight of 2: 1 supported on an alumina coating composition. The diesel oxidation catalyst was then aged in the oven in air at 750 ° C for 25 hours.
    [0088] Platinum / palladium are present in a concentration of 2,142 g / m3 (60 g / ft3) with a reactive coating composition charge of 189.03 kg / m3 (3.1 g / in3). Example 6
    [0089] A comparative catalyzed soot filter of the invention was prepared by coating a silicon carbide wall flow substrate as in Example 1 with platinum / palladium in a 10: 1 weight ratio supported on the alumina coating composition. The inlet channels were coated with 80% of the coating composition over 80% of the substrate axial length of the inlet ends and 20% of the coating composition was coated over 20% of the axial length of the outlet end substrate. The filter was then aged in the oven at 750 ° C for 10 hours.
    [0090] Platinum / palladium were present in a concentration of 1,785 g / m3 (50 g / ft3) with a reactive coating composition load of 21.34 kg / m3 (0.35 g / in3), with a D50 about 2.5 μm for both inlet and outlet coating compositions. The 2.5 μm D50 is indicative of wall cladding. Example 7
    [0091] Both catalytic soot filters of Example 4 and Example 6 were exposed to exhaust emissions from a 2.4 liter turbocharged diesel bench engine test. In both cases the DOC of Example 5 was positioned upstream of the catalytic soot filter. The engine was worked in such a way to obtain a temperature increase in sequence, in intervals of 25 ° C from 225 to 400 ° C and the temperature was maintained in each step 10 minutes after each temperature increase. Emission measurements were recorded downstream of the CSF at each temperature point and the results are shown in Figure 2,
    [0092] Figure 2 shows that the exhaust system of the liilkggiii filter ecVcnkucfq eqorctcVkxq fq Gzgornq 8 * tqVwncfq “Ref” pc Hkiwtc + Vgo a lower% NO2 / NOx ratio up to about 350 ° C compared to the exhaust system of the soot filter catalyzed according to the invention of Example 4. At about 350 ° C and above, the oxidation of NO to NO2 is thermodynamically limited, as is well known in the art. What happens is that for applications that require an increased% NO2 / NOx ratio, the exhaust system comprising the soot filter of Example 6 is preferred.
    [0093] To avoid any doubt, the complete contents of any and all documents of the prior art cited here are incorporated here for reference.
    权利要求:
    Claims (34)
    [0001]
    1. Catalytic soot filter for a diesel engine to increase the percentage of NO2 of total NOx in the exhaust gas leaving the catalytic soot filter compared to the percentage of NO2 of total NOx in the exhaust gas entering the catalytic soot filter, filter which is characterized by the fact that it comprises a wall flow substrate of ceramic or ceramic type having an average size of 4 to 40 μm and a porosity of 35 to 75% and comprising an inlet end and an outlet end, an axial length of substrate extending between the end of the inlet and the end of the outlet, and a plurality of channels defined by inner walls of the wall flow substrate, wherein the plurality of channels comprises a plurality of input channels having an end open inlet and a closed outlet end and a plurality of outlet channels having a closed inlet end and an open outlet end, Internal wall surfaces of the plurality of inlet channels comprise a reactive coating composition of at least one inlet coating composition comprising at least one refractory metal oxide, an optionally stabilized rare earth metal oxide or a mixture of at least one refractory metal oxide and an optionally stabilized rare earth metal oxide and both catalytically active metals platinum and palladium, wherein at least one inlet coating composition extends an axial inlet coating length from the inlet end open to a downstream inlet liner end, where the axial inlet liner length is less than the axial length of the substrate, where the outer surfaces of the inner walls of the plurality of outlet channels comprise a reactive liner composition of at least one outlet coating composition on the wall and comprising at least one refractory metal oxide, an optionally stabilized rare earth metal oxide or a mixture of at least one refractory metal oxide and an optionally stabilized rare earth metal oxide and both catalytically active metals platinum and palladium, wherein at least one outlet coating composition on the wall has an average particle size (D50) of between 4 and 15 μm and a D90 particle size greater than 15 μm and extending over an axial outlet coating length from a downstream outlet end to the open outlet end, where the axial outlet liner length is 55 to 90% of the axial length of the substrate and where the axial outlet liner length is greater than the length of axial inlet coating, wherein the at least one outlet coating composition on the wall has a thickness of 5 to 80 μm and comprises both platinum and palladium in a weight ratio Pt: Pd 20: 1 to 1: 1, wherein the at least one inlet coating composition comprises both platinum and palladium in a weight ratio Pt: Pd 20: 1 to 1:10 and where the weight ratio Pt : Pd in at least one inlet liner is less than the weight ratio Pt: Pd in the outlet liner.
    [0002]
    2. Catalytic soot filter according to claim 1, characterized in that the at least one catalytically active metal in the at least one outlet coating composition on the wall is present on the external surfaces of the inner walls of the outlet channel a a concentration of 35.7 to 5.355 g / m3 (1 to 150 g / ft3).
    [0003]
    Catalytic soot filter according to either of claims 1 or 2, characterized in that the refractory metal oxide in at least one outlet coating composition on the wall is selected from the group consisting of alumina, silica, silica-alumina, alumina silicates, alumina-zirconia, alumina-chromium, titania, titania-silica and titania-zirconia.
    [0004]
    4. Catalytic soot filter according to claim 5, characterized in that a load of at least one refractory metal oxide in at least one outlet coating composition on the wall is from 3.049 to 60.98 kg / m3 (0.05 to 1.0 g / in3).
    [0005]
    Catalytic soot filter according to any one of claims 1 to 4, characterized in that the rare earth metal oxide in at least one outlet coating composition on the wall comprises a cerium oxide, praseodymium, lanthanum , neodymium or samarium.
    [0006]
    6. Catalytic soot filter according to claim 5, characterized by the fact that a concentration of rare earth metal oxide in at least one outlet coating composition on the wall is 1,785 to 35,700 g / m3 (50 to 1,000 g / ft3).
    [0007]
    Catalytic soot filter according to any one of claims 1 to 6, characterized in that at least one outlet coating composition on the wall is present with a reactive coating composition charge of 6.098 to 121.96 kg / m3 (0.1 to 2.0 g / in3).
    [0008]
    Catalytic soot filter according to any one of claims 1 to 7, characterized in that the at least one inlet coating composition is at least one inlet coating composition on the wall over the outer surfaces of the inner walls the plurality of input channels.
    [0009]
    Catalytic soot filter according to claim 8, characterized in that the at least one inlet coating composition on the wall has an average particle size (D50) of between 4 and 15 μm.
    [0010]
    Catalytic soot filter according to any one of claims 1 to 9, characterized in that the at least one inlet coating composition is at least one coating composition within the wall.
    [0011]
    Catalytic soot filter according to claim 10, characterized in that the at least one inlet coating composition, within the wall has an average particle size (D50) of 1 to 3 μm.
    [0012]
    Catalytic soot filter according to claim 11, characterized by the fact that the inlet coating composition, within the wall, has a D90 particle size of 4 to 6 μm.
    [0013]
    Catalytic soot filter according to any one of claims 1 to 12, characterized in that the length of the axial inlet lining is 10 to 45% of the axial length of the substrate.
    [0014]
    Catalytic soot filter according to any one of claims 1 to 13, characterized in that the at least one catalytically active metal is present in the inlet coating composition on the channel walls at a concentration of 35.7 to 5,355 g / m3 (1 to 150 g / ft3).
    [0015]
    Catalytic soot filter according to any one of claims 1 to 14, characterized by the fact that at least one refractory metal oxide in at least one inlet coating composition is selected from the group consisting of alumina, silica, silica-alumina, alumina silicates, alumina-zirconia, alumina-chromium, titania, titania-silica and titania-zirconia.
    [0016]
    16. Catalytic soot filter according to claim 15, characterized in that a charge of at least one refractory metal oxide in at least one inlet coating composition is 3.049 to 60.98 kg / m3 (0, 05 to 1.0 g / in3).
    [0017]
    17. Catalytic soot filter according to any one of claims 1 to 16, characterized in that the at least one inlet coating composition comprises a rare earth metal oxide selected from a cerium oxide, praseodymium, lanthanum, neodymium and samarium.
    [0018]
    Catalytic soot filter according to claim 17, characterized in that a concentration of rare earth metal oxide in at least one inlet coating composition is 1,785 to 35,700 g / m3 (50 to 1,000 g / m3) ft3).
    [0019]
    19. Catalytic soot filter according to any one of claims 1 to 18, characterized in that at least one inlet coating composition is present with a reactive coating composition charge of 6.098 to 121.96 kg / m3 ( 0.1 to 2.0 g / in3).
    [0020]
    20. Catalytic soot filter according to any one of claims 1 to 19, characterized in that the coating composition on the inner wall surfaces of the inlet channel comprises the same ingredients as the coating composition on the outer wall surfaces output channel.
    [0021]
    21. Catalytic soot filter according to claim 20, characterized in that these same ingredients are present with the same reactive coating composition charge in the inlet coating composition and in the outlet coating composition on the wall.
    [0022]
    22. Catalytic soot filter according to any one of claims 1 to 21, characterized in that the axial inlet lining length is at least 10% longer than the axial inlet lining length when expressed as a percentage of the axial total length of substrate.
    [0023]
    23. Catalytic soot filter according to any one of claims 1 to 22, characterized in that the length of the axial inlet coating and the length of the axial outlet coating together are substantially equal to the length of the axial substrate.
    [0024]
    24. Catalytic soot filter according to any one of claims 1 to 23, characterized in that each reactive coating composition has an average porosity of 5 to 80% with an average void diameter of 0.1 to 1,000 μm.
    [0025]
    25. Catalytic soot filter according to any one of claims 1 to 24, characterized in that the wall flow substrate is a ceramic or ceramic type material.
    [0026]
    26. Catalytic soot filter according to any one of claims 1 to 25, characterized in that the wall flow substrate contains 23.3 to 62.0 channels per square centimeter of cross section and the internal walls of the substrate flow wall have a wall thickness of 15.2 to 55.9 thousandths of a centimeter.
    [0027]
    27. Exhaust system for a diesel engine, characterized by the fact that it comprises a catalyzed soot filter as defined in any of claims 1 to 26 and a selective catalytic reduction catalyst disposed downstream of the catalyzed soot filter.
    [0028]
    Exhaust system according to claim 27, characterized in that an oxidation catalyst to oxidize ammonia to N2 is arranged downstream of the selective catalytic reduction catalyst.
    [0029]
    29. Exhaust system for a diesel engine characterized by the fact that it comprises a catalyzed soot filter as defined in any one of claims 1 to 26 and a NOx absorber catalyst disposed downstream of the catalyzed soot filter.
    [0030]
    Exhaust system according to any one of claims 27 to 29, characterized in that a diesel oxidation catalyst is arranged downstream of the catalytic soot filter.
    [0031]
    Exhaust system according to claim 30, characterized in that the length of the axial inlet coating on the catalyzed soot filter is 10 to 30% of the axial length of the substrate.
    [0032]
    32. Method for increasing the% of the NO2 / NOx ratio in a diesel exhaust gas comprising NOx for downstream processes, a method characterized by the fact that it comprises contacting the exhaust gas with a catalyzed soot filter as defined in any of the claims 1 to 26 or an exhaust system as defined in any of claims 27 to 31.
    [0033]
    33. Method according to claim 32, characterized in that, when in use, the NO2: NO ratio in a total NOx content of the exhaust gas exiting the catalyzed soot filter is between 10:90 to 90: 10.
    [0034]
    34. The method of claim 32 or 33, characterized by the fact that the downstream process comprises selective catalytic reduction of nitrogen oxides using an SCR catalyst and a nitrogen reducer.
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    同族专利:
    公开号 | 公开日
    EP2917521B1|2019-07-24|
    US20140161693A1|2014-06-12|
    BR112015009514A2|2017-07-04|
    GB2510022B|2015-09-30|
    EP2917521A1|2015-09-16|
    JP6416098B2|2018-10-31|
    KR20150079869A|2015-07-08|
    US8940259B2|2015-01-27|
    GB201319294D0|2013-12-18|
    CN104838099A|2015-08-12|
    RU2015120598A|2016-12-20|
    JP2016500566A|2016-01-14|
    GB201219600D0|2012-12-12|
    RU2641814C2|2018-01-22|
    DE112013000180T5|2014-08-07|
    KR102178500B1|2020-11-13|
    GB2510022A|2014-07-23|
    WO2014068321A1|2014-05-08|
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    法律状态:
    2018-11-21| B06F| Objections, documents and/or translations needed after an examination request according art. 34 industrial property law|
    2020-03-24| B06U| Preliminary requirement: requests with searches performed by other patent offices: suspension of the patent application procedure|
    2020-12-01| B09A| Decision: intention to grant|
    2021-01-12| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 31/10/2013, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    GBGB1219600.2A|GB201219600D0|2012-10-31|2012-10-31|Catalysed soot filter|
    GB1219600.2|2012-10-31|
    US201261721713P| true| 2012-11-02|2012-11-02|
    US61/721,713|2012-11-02|
    PCT/GB2013/052851|WO2014068321A1|2012-10-31|2013-10-31|Catalysed soot filter|
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