Gasoline Particulate Filter

Abstract

1. A particulate filter comprising: a substrate including a plurality of porous walls (10) extending longitudinally to form a plurality of parallel flow passages extending from an inlet end (01) to an outlet end (02), a volume of the flow passages being inlet flow passages (11) that are open at the inlet end (01) and closed at the outlet end (02), and a volume of the flow passages being outlet flow passages (12) that are closed at the inlet end (01) and open at the outlet end (02); and a layer of inorganic particles loaded on a surface of the porous walls (10) in the inlet flow passages (11) and / or outlet flow passages (12) of the substrate, preferably at least in the inlet flow passages (11), the inorganic particles comprising a first inorganic component selected from alumina, zirconia, ceria, silica, titania, zinc oxide, zinc carbonate, calcium oxide, calcium carbonate, silicate zeolite, aluminosilicate zeolite, or any combination thereof, and manganese oxide as a second inorganic component.

Description

[Technical field]

[0001] The present invention relates to a particulate filter for treating an exhaust stream from a gasoline engine comprising an inorganic powder particle coating. The present invention also relates to a gasoline engine exhaust treatment system comprising the particulate filter and a method for treating an exhaust stream from a gasoline engine. [Background technology]

[0002] Engine exhaust consists essentially of gaseous pollutants such as unburned hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx), as well as particulate matter (PM). For gasoline engines, three-way conversion catalysts (hereinafter interchangeably referred to as TWC catalysts or TWC) for gaseous pollutants and filters for particulate matter (PM) are well-known exhaust treatment means to ensure that exhaust emissions meet emission regulations.

[0003] In contrast to particulates generated by diesel lean burn engines, particulates generated by gasoline engines, such as gasoline direct injection engines, tend to be finer and in smaller quantities. This is due to the different combustion conditions of gasoline engines compared to diesel engines. Also, the hydrocarbon components are different in the emissions of gasoline engines compared to diesel engines. Particulate filters specifically for gasoline engines have been developed over the decades to effectively treat engine exhaust from gasoline engines.

[0004] For example, WO 2018 / 024547 A1 describes a catalyzed particulate filter comprising a TWC catalytic material that permeates the walls of the particulate filter. Coating the TWC catalytic material on or within the filter may result in backpressure effects. To avoid excessive increases in backpressure while still providing full three-way conversion functionality, a specific coating scheme was proposed in the patent application. The catalyzed particulate filter is required to have a coated porosity that is smaller than the uncoated porosity of the particulate filter.

[0005] GB 2560663(B) describes a particulate filter for use in the exhaust treatment system of a gasoline engine, the filter having an inlet side and an outlet side, at least the inlet side containing particulate matter of less than D 90 and loaded with synthetic ash containing one or more of aluminum oxide, zinc oxide, zinc carbonate, calcium oxide, calcium carbonate, cerium zirconium (mixed) oxide, zirconium oxide, cerium oxide, and hydrated alumina. The synthetic ash is described as being devoid of platinum group metal-containing catalytic materials and catalyst poisoning materials sulfur oxides, phosphorus, magnesium, manganese, and lead.

[0006] It is known that the filtration performance of gasoline particulate filters improves over the life of the filter, mainly as a result of the accumulation of ash and soot on the inlet walls of the filter. It has also been determined that the particle count of the exhaust generated during the cold start phase of the test cycle represents the majority of the total particles emitted during the test. Therefore, the particle filtration performance during the initial filtration phase, also called fresh filtration efficiency, is a major concern for developing gasoline particulate filters.

[0007] As particulate emissions from gasoline engines are subject to stricter regulations such as Euro 6 and China 6, vehicle manufacturers, i.e., original equipment manufacturers (OEMs), are requiring gasoline particulate filters to have high fresh filtration efficiency.

[0008] Gasoline particulate filters require regeneration when the pressure drop becomes unacceptable due to soot buildup, so the regeneration performance of gasoline particulate filters is also an important consideration.

[0009] There is a need to provide an improved particulate filter for treating exhaust streams from gasoline engines that can exhibit higher fresh filtration efficiency under low backpressure and / or desirable regeneration performance. Summary of the Invention

[0010] It is an object of the present invention to provide a particulate filter for treating an exhaust stream from a gasoline engine that exhibits higher fresh filtration efficiency and / or exhibits desirable regeneration performance without experiencing unacceptable backpressure increase.

[0011] Surprisingly, it has been found that the objects of the invention are achieved by a particulate filter comprising a layer of inorganic powder particles in the inlet and / or outlet flow paths of the filter.

[0012] Thus, in a first aspect, the present invention provides a particulate filter comprising: a substrate including a plurality of porous walls extending longitudinally to form a plurality of balanced flow paths, the plurality of parallel flow paths extending from an inlet end to an outlet end, a volume of the flow paths being inlet flow paths that are open at the inlet end and closed at the outlet end, and a volume of the flow paths being outlet flow paths that are closed at the inlet end and open at the outlet end; a layer of inorganic particles loaded on the surface of the porous walls in the inlet and / or outlet channels of the substrate, A particulate filter is provided, in which the inorganic particles include a first inorganic component selected from alumina, zirconia, ceria, silica, titania, zinc oxide, zinc carbonate, calcium oxide, calcium carbonate, silicate zeolite, aluminosilicate zeolite, or any combination thereof, and manganese oxide as a second inorganic component.

[0013] In a second aspect, the present invention provides a method for producing a particulate filter, comprising the steps of: - providing a substrate including a plurality of porous walls extending longitudinally to form a plurality of parallel flow paths extending from an inlet end to an outlet end, a quantity of the flow paths being inlet flow paths that are open at the inlet end and closed at the outlet end, and a quantity of the flow paths being outlet flow paths that are closed at the inlet end and open at the outlet end; applying inorganic particles onto a surface of a porous wall in an inlet flow channel and / or an outlet flow channel of the substrate, the inorganic particles comprising a first inorganic component selected from alumina, zirconia, ceria, silica, titania, zinc oxide, zinc carbonate, calcium oxide, calcium carbonate, silicate zeolite, aluminosilicate zeolite, or any combination thereof, and manganese oxide as a second inorganic component.

[0014] In a third aspect, the present invention provides an exhaust gas treatment system comprising a particulate filter according to the first aspect or obtainable from or obtained by the method according to the second aspect, positioned downstream of a petrol engine.

[0015] In a fourth aspect, the present invention provides a method for treating an exhaust stream from a gasoline engine comprising contacting the exhaust stream with a particulate filter according to the first aspect or an exhaust treatment system according to the third aspect.

[0016] It has been found that a particulate filter according to the present invention for treating an exhaust stream from a gasoline engine, also referred to herein as a gasoline particulate filter, can provide improved fresh filtration efficiency compared to its prior art counterpart, while no significant backpressure increase was observed. The gasoline particulate filter has also been found to exhibit significantly improved regeneration performance. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 shows an external view of a wall flow substrate having an inlet end and an outlet end. [Diagram 2] FIG. 1 illustrates a longitudinal cross-section of an exemplary wall-flow substrate having multiple porous walls extending longitudinally from the inlet end to the outlet end of the substrate. [Figure 3A] 1 shows THC conversion for particulate filters of Example 2 of the present invention and Comparative Example 3. [Figure 3B] 1 shows the CO conversion for the particulate filters of Example 2 of the present invention and Comparative Example 3. [Figure 3C] 2 shows NOx conversion for the particulate filters of Example 2 of the present invention and Comparative Example 3. [Figure 4A] 1 shows the inlet temperature (T-in) and bed temperature (T-bed) for the particulate filter of Comparative Example 4 during soot combustion activity measurements. [Figure 4B] 1 shows the inlet temperature (T-in) and bed temperature (T-bed) for the particulate filter of Example 4 of the present invention during soot combustion activity measurements. [Figure 5A] 1 shows the O2 concentration for both the inlet (O2-in) and outlet (O2-out) of the particulate filter of Comparative Example 4 during the measurement of soot combustion activity. [Figure 5B] 1 shows the O2 concentration for both the inlet (O2-in) and outlet (O2-out) of the particulate filter of Example 4 of the present invention during the measurement of soot combustion activity. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The present invention will be described in detail herein below. It should be understood that the present invention can be embodied in many different ways and should not be construed as being limited to the embodiments set forth herein.

[0019] The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Terms such as "comprise," "comprising," and the like are used interchangeably with "contain," "containing," and the like, and are to be interpreted in an open, non-restrictive manner; that is, for example, additional components or elements may be present. The expression "consists of" or cognates may be included in "comprises" or cognates.

[0020] As used herein, the term "layer" in the context of, for example, a layer of inorganic particles is intended to mean a thin gas-permeable coating of material loaded onto a blank or pre-coated wall of a substrate. The layer may be in the form of particles packed onto the wall of the substrate, with gaps between them that allow gas to pass through.

[0021] "D 90 The terms " have their ordinary meaning, referring to the point in the cumulative particle size distribution where the cumulative volume from the small particle size end reaches 90%. 90 is a value determined by measuring the particle size distribution. The particle size distribution is measured by using a laser diffraction particle size distribution measuring device.

[0022] Terms for platinum group metal (PGM) components, such as "palladium component," "platinum component," and "rhodium component," are intended to describe the presence of the respective platinum group metal in any possible valence state, which may be, for example, the metal or metal oxide as a catalytically active form, or may be a metal compound, complex, etc. that decomposes or is otherwise converted to a catalytically active form, for example, upon calcination or use of the catalyst.

[0023] The term "support" refers to a material in particulate form for receiving and carrying one or more PGM components, and optionally one or more other components, such as stabilizers, promoters, and binders.

[0024] In this specification, g / ft 3 or g / in 3 Any reference to loading in units is intended to mean the weight of a particular component, coat, or layer per unit volume of the substrate on which it is loaded.

[0025] According to a first aspect of the present invention there is provided a particulate filter comprising: a substrate including a plurality of porous walls extending longitudinally to form a plurality of balanced flow paths, the plurality of parallel flow paths extending from an inlet end to an outlet end, a volume of the flow paths being inlet flow paths that are open at the inlet end and closed at the outlet end, and a volume of the flow paths being outlet flow paths that are closed at the inlet end and open at the outlet end; a layer of inorganic particles loaded on the surface of the porous walls in the inlet and / or outlet channels of the substrate, A particulate filter is provided, in which the inorganic particles comprise a first inorganic component selected from alumina, zirconia, ceria, silica, titania, zinc oxide, zinc carbonate, calcium oxide, calcium carbonate, silicate zeolite, aluminosilicate zeolite, or any combination thereof, and manganese oxide as a second inorganic component.

[0026] Substrate, as used herein, refers to a structure suitable for withstanding the conditions encountered in the exhaust stream from a combustion engine, which can itself function as a particulate filter, and which can also be loaded with functional materials, e.g., a filtration improving layer, such as a layer of inorganic particles as described herein, and optionally any other layers.

[0027] The substrate includes a plurality of porous walls extending longitudinally to form a plurality of parallel flow passages extending from an inlet end to an outlet end, with an amount of the flow passages being inlet flow passages that are open at the inlet end and closed at the outlet end, and an amount of the flow passages different from the inlet flow passages being outlet flow passages that are closed at the inlet end and open at the outlet end. The substrate configuration, also referred to as a wall-flow substrate, requires that engine exhaust in the inlet flow passages flows through the porous walls of the substrate and into the outlet flow passages to reach the outlet end.

[0028] Generally, the substrate may exhibit a honeycomb structure, with alternating channels blocked by plugs at both ends.

[0029] The porous walls of the substrate are generally made from a ceramic or metallic material. Suitable ceramic materials used to construct the substrate may include any suitable refractory material, such as cordierite, mullite, cordierite-alumina, silicon carbide, silicon nitride, zirconia, mullite, spodumene, alumina-silica-magnesia, zirconium silicate, magnesium silicate, sillimanite, petalite, alumina, aluminum titanate, and aluminosilicates. Typically, the porous walls of the substrate are made from cordierite or silicon carbide.

[0030] Suitable metallic materials for constructing the substrate may include heat-resistant metals and metal alloys, such as titanium and stainless steel, as well as other alloys in which iron is a substantial or major component. Such alloys may contain one or more of nickel, chromium, and / or aluminum, the total amount of these metals advantageously comprising at least 15% by weight of the alloy, for example 10-25% by weight chromium, 3-8% by weight aluminum, and up to 20% by weight nickel. The alloys may contain small or trace amounts of one or more metals, such as manganese, copper, vanadium, titanium, etc. The surface of the metal substrate may be oxidized at high temperatures, for example 1000° C. or higher, to form an oxide layer on the surface of the substrate to improve the corrosion resistance of the alloy and promote adhesion of a washcoat layer to the metal surface.

[0031] The flow passage at the closed end is filled with a plug of sealant material. Any suitable sealant material may be used without limitation.

[0032] The channels of the substrate can be of any suitable cross-sectional shape and size, such as circular, elliptical, triangular, rectangular, square, hexagonal, trapezoidal, or other polygonal. The substrate may have up to 700 channels (i.e., cells) per square inch of cross section. For example, the substrate may have 100 to 500 cells per square inch ("cpsi"), typically 200 to 400 cpsi. The walls of the substrate may have a variety of thicknesses, with typical ranges being 2 mils to 0.1 inches. Preferably, the substrate has a number of inlet channels equal to the number of outlet channels, and the channels are uniformly distributed throughout the substrate.

[0033] 1 and 2 show a typical wall-flow substrate that contains multiple inlet and outlet channels.

[0034] 1 shows a schematic external view of a wall-flow substrate having an inlet end (01) where the exhaust stream (13) enters the substrate and an outlet end (02) where treated exhaust exits. Alternate flow paths are plugged to form a checkerboard pattern at the inlet end (01) as shown, and an opposite checkerboard pattern at the outlet end (02), not shown.

[0035] 2 shows a schematic longitudinal cross-section of a wall-flow substrate including a first plurality of flow channels (11) that are open at an inlet end (01) and closed at an outlet end (02) and a second plurality of flow channels (12) that are open at the outlet end (02) and closed at the inlet end (01). The flow channels are preferably parallel to each other to provide a constant wall thickness between the flow channels. Exhaust flow entering the first plurality of flow channels from the inlet end cannot exit the substrate without diffusing through the porous wall (10) into the second plurality of flow channels.

[0036] The particulate filter according to the present invention may comprise a layer of inorganic particles loaded on the surface of the porous walls in the inlet and / or outlet flow paths of the substrate. In other words, the layer of inorganic particles may be loaded on the porous walls only in the inlet flow paths, only in the outlet flow paths, or both inlet and outlet flow paths. In particular, the layer of inorganic particles may be loaded on the porous walls only in the inlet flow paths, or both inlet and outlet flow paths, more preferably only in the inlet flow paths.

[0037] The layer of inorganic particles is intended to be loaded onto the surface of the porous walls in the inlet and / or outlet flow paths, also referred to as an "on-wall" coat, although it will be understood that a small amount of the inorganic particles may penetrate into the pores in the porous walls.

[0038] The inorganic particles contain the first inorganic component in an amount of 30-97%, particularly 50-97%, based on the total weight of the inorganic particles. For example, the inorganic particles contain the first inorganic component in an amount of 30%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 65%, 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 95%, 96%, or 97%. In particular, the inorganic particles contain the first inorganic component in an amount of 85-97%, 88-96%, or 90-96%, based on the total weight of the inorganic particles. Alternatively, the inorganic particles contain the first inorganic component in an amount of 30-60%, 50-60%, or 54-58%, based on the total weight of the inorganic particles.

[0039] The inorganic particles contain the second inorganic component in an amount of 3-70%, particularly 3-50%, based on the total weight of the inorganic particles. For example, the inorganic particles contain the second inorganic component in an amount of 3%, 4%, 5%, 10%, 11%, 12%, 13%, 14%, 15%, 20%, 25%, 30%, 35%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, or 70%. In particular, the inorganic particles contain the second inorganic component in an amount of 3-15%, 4-12%, or 4-10%, based on the total weight of the inorganic particles. Alternatively, the inorganic particles contain the first inorganic component in an amount of 40-70%, 40-50%, or 42-46%, based on the total weight of the inorganic particles.

[0040] In some embodiments, the inorganic particles comprise a first inorganic component in an amount of 85-97% and a second inorganic component in an amount of 3-15% based on the total weight of the inorganic particles. Further, the inorganic particles may comprise a first inorganic component in an amount of 88-96% and a second inorganic component in an amount of 4-12% based on the total weight of the inorganic particles. In particular, the inorganic particles comprise a first inorganic component in an amount of 90-96% and a second inorganic component in an amount of 4-10% based on the total weight of the inorganic particles.

[0041] In some other embodiments, the inorganic particles include a first inorganic component in an amount of 30-60% and a second inorganic component in an amount of 40-70% based on the total weight of the inorganic particles. Further, the inorganic particles may include a first inorganic component in an amount of 50-60% and a second inorganic component in an amount of 40-50% based on the total weight of the inorganic particles. In particular, the inorganic particles may include a first inorganic component in an amount of 54-58% and a second inorganic component in an amount of 42-46% based on the total weight of the inorganic particles.

[0042] The amount of the first inorganic component refers to the total amount of each component when there is more than one species present as the first inorganic component.

[0043] The amount of second inorganic component refers to the total amount of manganese oxide calculated as MnO2 when manganese oxides having different oxidation states are present as the second component.

[0044] The first inorganic component is preferably one or more selected from alumina, zirconia, ceria, silica, titania, zinc oxide, and rare earth metal oxides other than ceria. More preferably, the first inorganic component is one or more selected from alumina, zirconia, and zinc oxide. In particular, the first inorganic component includes or is alumina.

[0045] The manganese oxide as the second inorganic component may be selected from any state of oxide of manganese, such as one or more of MnO2, MnO, Mn2O, Mn2O3, Mn3O4, and Mn2O7. Preferably, the second inorganic component includes or is MnO2.

[0046] It should be understood that each of the first and second inorganic components, when there is more than one species present as the first or second inorganic component, may be a physical mixture of the two or more species, or a composite of the two or more species, as described above.

[0047] The first inorganic component and the second inorganic component may be included in the form of a physical mixture of particles of each, ie, a mixture of particles of the first inorganic component with particles of the second inorganic component.

[0048] Alternatively, the first inorganic component and the second inorganic component may be included in the form of a particle of their composite. For example, the first inorganic component may be doped with and / or carry the second inorganic component. In other words, the species of the first inorganic component and the species of the second inorganic component are found in a single particle.

[0049] The inorganic particles may optionally include a PGM component, such as a palladium component and / or a platinum component, which, if present, may be supported on or separate from the first component and / or the second component.

[0050] As used herein, the layer of inorganic particles loaded on the porous walls in the inlet and / or outlet channels of the substrate refers specifically to a layer that exhibits little or no, preferably no, TWC activity, although it may exhibit certain catalytic activity when one or more PGM components are included in the inorganic particles.

[0051] In some embodiments, the inorganic particles are free of PGM components and preferably comprise a first inorganic component and a second inorganic component.

[0052] Particulate filters are 0.005 to 0.83 g / in 3 (i.e., about 0.3 to 50 g / L), or 0.01 to 0.33 g / in 3 (i.e., about 0.6 to 20 g / L), or 0.02 to 0.17 g / in 3 (i.e., about 1.2 to 10 g / L), or 0.025 to 0.1 g / in 3 (i.e., about 1.5-6 g / L) of inorganic particles.

[0053] The layer of inorganic particles may be applied onto the surfaces of the porous walls of the channels of the substrate by any known process, such as dry coating and wash coating processes.

[0054] Dry coating processes are well known and are generally carried out by blowing inorganic particles or suitable precursors thereof in particulate form into the channels of the substrate through an open end with a carrier gas stream and then firing the coated substrate. With this process, no liquid carrier is used. The inorganic particles are typically distributed on the surface of the porous walls of the channels in the form of a particle bed.

[0055] In some embodiments, inorganic particles or suitable precursors thereof may be injected into the inlet channel from the open end of the channel toward the closed end. The particle bed formed in the inlet channel may be disposed on the porous walls of the inlet channel or against a plug blocking the channel. As discussed above, the particulate bed, i.e., the layer of inorganic particles, is gas permeable, which may contribute to the capture of particulate matter (PM) in the exhaust stream and allow gaseous pollutants in the exhaust stream to pass therethrough.

[0056] The layer of inorganic particles in the form of a particle bed may extend along the porous walls of the flow channel in which the inorganic particles are loaded. It will be understood that the particle bed may extend along the entire length of the porous walls of the flow channel or along only a portion of the length of the porous walls of the flow channel.

[0057] Wash-coating processes are also well known and are generally carried out by coating a slurry containing inorganic particles or suitable precursors thereof and any auxiliary agents in a liquid solvent (e.g., water) into the channels of the substrate from an open end, and drying and firing the coated substrate. The layer of inorganic particles applied by wash-coating may be in the form of a porous coating and may extend along the porous walls of the channels in which the inorganic particles are loaded. Also, the porous coating may extend along the entire length of the porous walls of the channels or only along a portion of the length of the porous walls of the channels.

[0058] Particulate filters according to the present invention may further comprise a TWC coating in at least a portion of the inlet and / or outlet flow paths of the substrate. In particular, the TWC coating is present in both the inlet and outlet flow paths of the substrate.

[0059] The TWC coat is typically in the form of a washcoat, also called an "in-wall" coat, that includes the TWC composition.

[0060] It will be understood that although the TWC coat is intended to be loaded into the pores of the porous walls of the flow channels, a significant amount of the TWC composition may also be found on the surfaces of the porous walls within the coated flow channels.

[0061] There is no particular limit to the TWC composition useful for the TWC coating contained in the particulate filter.Typically, the TWC composition includes a platinum group metal component as a catalytically active species, such as a rhodium component, and one or both of a platinum component and a palladium component, which are supported on a support particle.Materials useful as a support may be refractory metal oxides, oxygen storage components, and any combination thereof.

[0062] Examples of refractory metal oxides may include, but are not limited to, alumina, lanthana-doped alumina, baria-doped alumina, ceria-doped alumina, zirconia-doped alumina, ceria-zirconia-doped alumina, lanthana-zirconia-doped alumina, baria-lanthana-doped alumina, baria-ceria-doped alumina, baria-zirconia-doped alumina, baria-lanthana-neodymia-doped alumina, lanthana-ceria-doped alumina, and any combination thereof.

[0063] Examples of oxygen storage components (OSCs) may include, but are not limited to, reducible rare earth metal oxides such as ceria. The oxygen storage component may also include one or more of lanthana, praseodymia, neodymia, europia, samaria, ytterbia, yttria, zirconia, and hafnia to form a composite oxide with ceria. In particular, the oxygen storage component is selected from ceria-zirconia composite oxides and stabilized ceria-zirconia composite oxides.

[0064] The particulate filter of the present invention has a particle size of 0.1 to 5.0 g / in 3 (i.e., about 6.1 to 305.1 g / L), or 0.5 to 3.0 g / in 3 (i.e., about 30.5 to 183.1 g / L), or 0.8 to 2 g / in3 (i.e., about 49-122 g / L) of TWC coat.

[0065] TWC coating has a range of 1.0 to 50.0 g / ft2 calculated for each PGM element. 3 (i.e., about 0.04 to 1.8 g / L), or 5.0 to 20.0 g / ft 3 (i.e., about 0.18-0.71 g / L) total loading of PGM components.

[0066] The TWC coat may be applied onto the substrate by any known process, typically by a washcoating process, which is generally carried out by coating a slurry containing TWC catalyst particles of the supported PGM components in a solvent (e.g. water) and optionally coagents, and drying and calcining the coated substrate.

[0067] The TWC coat, if present, is applied onto the substrate prior to loading with the layer of inorganic particles as described above.

[0068] In some exemplary embodiments, a particulate filter according to the present invention comprises: a substrate including a plurality of porous walls extending longitudinally to form a plurality of balanced flow paths, the plurality of parallel flow paths extending from an inlet end to an outlet end, a volume of the flow paths being inlet flow paths that are open at the inlet end and closed at the outlet end, and a volume of the flow paths being outlet flow paths that are closed at the inlet end and open at the outlet end; a layer of inorganic particles loaded on the surface of the porous walls at least in the inlet channels of the substrate; - optionally comprising a TWC coat, preferably a washcoat comprising a TWC composition, the inorganic particles comprise a first inorganic component selected from alumina, zirconia, ceria, silica, titania, zinc oxide, zinc carbonate, calcium oxide, calcium carbonate, silicate zeolite, aluminosilicate zeolite, or any combination thereof, and manganese oxide as a second inorganic component; The second inorganic component is included in an amount of 3 to 15% or 40 to 70% based on the total weight of the inorganic particles.

[0069] In a further exemplary embodiment, the particulate filter according to the present invention comprises: a substrate including a plurality of porous walls extending longitudinally to form a plurality of balanced flow paths, the plurality of parallel flow paths extending from an inlet end to an outlet end, a volume of the flow paths being inlet flow paths that are open at the inlet end and closed at the outlet end, and a volume of the flow paths being outlet flow paths that are closed at the inlet end and open at the outlet end; a layer of inorganic particles loaded on the surface of the porous walls at least in the inlet channels of the substrate; optionally comprising a washcoat comprising a TWC composition; the inorganic particles comprise a first inorganic component selected from alumina, zirconia, zinc oxide, or any combination thereof, and a manganese oxide as a second inorganic component; The second inorganic component is included in an amount of 3 to 15% or 40 to 70% based on the total weight of the inorganic particles.

[0070] In some other exemplary embodiments, a particulate filter according to the present invention comprises: a substrate including a plurality of porous walls extending longitudinally to form a plurality of balanced flow paths, the plurality of parallel flow paths extending from an inlet end to an outlet end, a volume of the flow paths being inlet flow paths that are open at the inlet end and closed at the outlet end, and a volume of the flow paths being outlet flow paths that are closed at the inlet end and open at the outlet end; a layer of inorganic particles loaded on the surface of the porous walls at least in the inlet channels of the substrate; optionally comprising a washcoat comprising a TWC composition; the inorganic particles comprise a first inorganic component selected from alumina, zirconia, zinc oxide, or any combination thereof, and a manganese oxide as a second inorganic component; The second inorganic component is included in an amount of 4 to 12% or 40 to 50% based on the total weight of the inorganic particles.

[0071] In the exemplary embodiment described above, the layer of inorganic particles is preferably free of PGM components.

[0072] The particulate filter may be housed within a shell having an inlet and an outlet for the exhaust flow, which may be operatively associated with and in fluid communication with other portions of the engine's exhaust treatment system.

[0073] According to a second aspect of the invention there is provided a method for producing a particulate filter comprising the steps of: - providing a substrate including a plurality of porous walls extending longitudinally to form a plurality of parallel flow paths extending from an inlet end to an outlet end, a quantity of the flow paths being inlet flow paths that are open at the inlet end and closed at the outlet end, and a quantity of the flow paths being outlet flow paths that are closed at the inlet end and open at the outlet end; applying inorganic particles onto a surface of a porous wall in an inlet flow channel and / or an outlet flow channel of the substrate, the inorganic particles comprising a first inorganic component selected from alumina, zirconia, ceria, silica, titania, zinc oxide, zinc carbonate, calcium oxide, calcium carbonate, silicate zeolite, aluminosilicate zeolite, or any combination thereof, and manganese oxide as a second inorganic component.

[0074] The inorganic particles may be applied onto the surface of the porous wall by a dry coating process or wash coating as described above in the first embodiment, preferably a dry coating process.

[0075] In some embodiments, the method for manufacturing a particulate filter further comprises applying a TWC coating to at least some of the porous walls of the inlet and / or outlet flow paths of the substrate prior to applying the inorganic particles onto the surfaces of the porous walls. The TWC coating may be applied by the washcoating process described above.

[0076] Any general descriptions and selections made above regarding the inorganic particles and the TWC coat in the first embodiment are applicable herein by reference. According to a third aspect, there is provided an exhaust gas treatment system comprising a particulate filter according to the first aspect or obtainable or obtained from the method according to the second aspect, and positioned downstream of a petrol engine.

[0077] According to a fourth aspect, there is provided a method of treating an exhaust stream from a gasoline engine comprising contacting the exhaust stream with a particulate filter according to the first aspect or an exhaust treatment system according to the third aspect.

[0078] Embodiment Various embodiments are listed below. It will be understood that the embodiments listed below can be combined with all aspects and other embodiments in accordance with the scope of the present invention.

[0079] 1. A particulate filter comprising: a substrate including a plurality of porous walls extending longitudinally to form a plurality of balanced flow paths, the plurality of parallel flow paths extending from an inlet end to an outlet end, a volume of the flow paths being inlet flow paths that are open at the inlet end and closed at the outlet end, and a volume of the flow paths being outlet flow paths that are closed at the inlet end and open at the outlet end; a layer of inorganic particles loaded on the surface of the porous walls in the inlet and / or outlet channels of the substrate, preferably at least in the inlet channels, 1. A particulate filter, comprising inorganic particles comprising a first inorganic component selected from alumina, zirconia, ceria, silica, titania, zinc oxide, zinc carbonate, calcium oxide, calcium carbonate, silicate zeolite, aluminosilicate zeolite, or any combination thereof, and manganese oxide as a second inorganic component. 2. The particulate filter of embodiment 1, wherein the first inorganic component is one or more selected from alumina, zirconia, ceria, silica, titania, zinc oxide, and rare earth metal oxides other than ceria. 3. The particulate filter of embodiment 2, wherein the first inorganic component is one or more selected from alumina, zirconia, and zinc oxide. 4. The particulate filter of embodiment 3, wherein the first inorganic component comprises or is alumina. 5. The particulate filter according to any one of the preceding embodiments, wherein the layer of inorganic particles does not exhibit three-way conversion catalytic activity. 6. The particulate filter according to any one of the preceding embodiments, wherein the layer of inorganic particles is free of PGM components. 7. The particulate filter of any one of the preceding embodiments, further comprising a three-way catalyst (TWC) coat, preferably a washcoat comprising a TWC composition. 8. The particulate filter of embodiment 7, wherein a three-way conversion catalyst coating is on at least a portion of the inlet and / or outlet flow paths of the substrate. 9. The layer of inorganic particles is 0.005 to 0.83 g / in 3 (i.e., about 0.3 to 50 g / L), or 0.01 to 0.33 g / in 3 (i.e., about 0.6 to 20 g / L), or 0.02 to 0.17 g / in 3 (i.e., about 1.2 to 10 g / L), or 0.025 to 0.1 g / in 3 (i.e., about 1.5-6 g / L). 10. The particulate filter of any one of embodiments 1 to 9, which is a gasoline particulate filter. 11. The particulate filter of any one of the preceding embodiments, wherein the inorganic particles comprise the second inorganic component in an amount of 3-70% or 3-50%, based on the total weight of the inorganic particles. 12. The particulate filter of embodiment 11, wherein the inorganic particles comprise the second inorganic component in an amount of 3-15%, 4-12%, or 4-10%, based on the total weight of the inorganic particles. 13. The particulate filter of embodiment 11, wherein the inorganic particles comprise the second inorganic component in an amount of 40-70%, 40-50%, or 42-46%, based on the total weight of the inorganic particles. 14. A method for producing a particulate filter according to any one of embodiments 1 to 13, comprising: - providing a substrate including a plurality of porous walls extending longitudinally to form a plurality of parallel flow paths extending from an inlet end to an outlet end, a quantity of the flow paths being inlet flow paths that are open at the inlet end and closed at the outlet end, and a quantity of the flow paths being outlet flow paths that are closed at the inlet end and open at the outlet end; applying inorganic particles onto a surface of a porous wall in an inlet flow channel and / or an outlet flow channel of a substrate, the inorganic particles comprising a first inorganic component selected from alumina, zirconia, ceria, silica, titania, zinc oxide, zinc carbonate, calcium oxide, calcium carbonate, silicate zeolite, aluminosilicate zeolite, or any combination thereof, and manganese oxide as a second inorganic component. 15. The method according to embodiment 14, wherein the inorganic particles are applied by a dry coating process or a wash coating process, preferably by a dry coating process. 16. The method of embodiment 15, wherein the inorganic particles are applied by using inorganic particles or precursors thereof. 17. An exhaust gas treatment system comprising a particulate filter according to any one of embodiments 1 to 13 or obtainable or obtained by the method according to any one of embodiments 14 to 16, the exhaust gas treatment system being arranged downstream of a gasoline engine. 18. A method for treating an exhaust stream from a gasoline engine, comprising contacting the exhaust stream with a particulate filter according to any one of embodiments 1-13 or an exhaust treatment system according to embodiment 17.

[0080] Aspects of the present invention will be more fully illustrated by the following examples, which are provided to illustrate particular aspects of the invention and are not to be construed as limiting thereof. EXAMPLES

[0081] I. Preparation of Particulate Filter Reference example 1 A gasoline particulate filter cordierite substrate was used as the reference filter (blank filter), which had a size of 143.8 mm (D) x 123.2 mm (L) and a volume of 2.0 L (approximately 122.1 in 3 ), a cell density of 300 cells per square inch (cpsi), a wall thickness of 8 mils, and a porosity of 65% as determined by mercury intrusion measurements.

[0082] Comparative Example 1 A TWC-coated particulate filter was prepared from the same filter substrate as the blank filter of Example 1 by applying a TWC washcoat to both the inlet and outlet channels of the blank filter.

[0083] 30.22 g of 9.68 wt% rhodium nitrate aqueous solution was impregnated onto 255 g of high surface area gamma alumina powder in a planetary mixer (P-mixer) to form a wet powder while achieving incipient wetness. 14.27 g of 20.5 wt% palladium nitrate aqueous solution was impregnated onto 711 g of ceria / zirconia (40% ceria) composite powder in a planetary mixer (P-mixer) to form a wet powder while achieving incipient wetness. An aqueous slurry was formed by mixing the above two wet powders with 1280 g of deionized water, to which 78 g of barium hydroxide octahydrate and 66 g of 21.5 wt% zirconium nitrate aqueous solution were added. The pH of the slurry was adjusted to 3.6 with nitric acid. The slurry was mixed to obtain a particle size D of 4.5 μm. 90 The blank filter was ground to a powder and then coated into the inlet channels of the blank filter at 50% washcoat loading and into the outlet channels of the blank filter at the remaining 50% washcoat loading. The coated substrate was dried at a temperature of 150° C. for 1 hour and then calcined at a temperature of 550° C. for 1 hour.

[0084] Approximately 0.99g / in 3 (60g / L) washcoat loading and approximately 10.0g / ft 3An in-wall TWC coat was obtained using a total PGM loading of (0.35 g / L) and a Pd / Rh ratio of 5 / 5.

[0085] Comparative Example 2 A particulate filter was prepared having a TWC coating and a layer of inorganic particles of Al2O3.

[0086] First, a particulate filter with a TWC coating was prepared by repeating the same process as described in Comparative Example 1. Then, high surface area gamma alumina powder was mixed with a carrier gas and stirred at 600 m at room temperature. 3 The alumina powder was blown into the inlet channel of the filter at a flow rate of 100000 / h. The alumina powder had a particle size D of 4.8 μm as measured by a Sympatec HELOS laser diffraction particle size analyzer. 90 The specific surface area after calcination at 1100°C for 4 hours in air (BET model, 77K nitrogen adsorption measurement) is 61m 2 After coating, the filter with the layer of inorganic particles in the inlet channels was fired at a temperature of 550° C. for 1 hour. The loading of alumina particles in the functional material layer was 3 g / L (0.05 g / in 3 ) was.

[0087] Comparative Example 3 A particulate filter having a TWC coat and a layer of inorganic particles was prepared by repeating the same process as described in Comparative Example 2, and then aged at 1000° C. for 4 hours in an atmosphere of 10% water vapor in air.

[0088] Comparative Example 4 A particulate filter having a layer of inorganic particles of Al2O3 was prepared.

[0089] A particulate filter having a layer of inorganic particles was prepared from a filter substrate, which had a size of 132.1 mm (D) x 120 mm (L) and a volume of 1.64 L (approximately 100.4 in 3 ), a cell density of 200 cells per square inch (cpsi), a wall thickness of 8.5 mils, and a porosity of 55% as determined by mercury intrusion measurements.

[0090] High surface area gamma alumina powder is mixed with carrier gas and heated to 600m at room temperature. 3 The alumina powder was blown into the inlet channel of the filter at a flow rate of 100000 / h. The alumina powder had a particle size D of 4.8 μm as measured by a Sympatec HELOS laser diffraction particle size analyzer. 90 The specific surface area after calcination at 1100°C for 4 hours in air (BET model, 77K nitrogen adsorption measurement) was 61m 2 / g.

[0091] After coating, the filter with the layer of inorganic particles in the inlet channels was calcined at a temperature of 550° C. for 1 hour. The loading of alumina particles in the layer of inorganic particles was 3.75 g / L (approximately 0.06 g / in 3 ) was.

[0092] Comparative Example 5 A particulate filter was prepared having a TWC coating and a layer of inorganic particles of Al2O3 and MnO2 (50:1).

[0093] First, a particulate filter with a TWC coat was prepared by repeating the same process as described in Comparative Example 1. Then, a mixture of high surface area gamma alumina powder and manganese dioxide (MnO2) in a weight ratio of 50:1 was mixed with a carrier gas and stirred at 600 m at room temperature. 3 The alumina powder was blown into the inlet channel of the filter at a flow rate of 100000 / h. The alumina powder had a particle size D of 4.8 μm as measured by a Sympatec HELOS laser diffraction particle size analyzer. 90 The specific surface area after calcination at 1100°C for 4 hours in air (BET model, 77K nitrogen adsorption measurement) was 61m 2 The MnO2 powder was dry-milled to a particle size of 6.8 μm, D 90 It has been pre-processed.

[0094] After coating, the filter with the layer of inorganic particles in the inlet channels was calcined at a temperature of 550° C. for 1 hour. The loading of alumina in the layer of inorganic particles was 3 g / L (approximately 0.05 g / in 3 The MnO2 loading was 0.06 g / L (approximately 0.001 g / in 3 ) was.

[0095] Example 1 of the present invention A particulate filter having a TWC coating and a layer of inorganic particles of Al2O3 and MnO2 (20:1) was prepared by repeating the same process as described in Comparative Example 5, except that the weight ratio of alumina powder to manganese dioxide powder was 20:1. The loading of alumina in the layer of inorganic particles was 3 g / L (about 0.05 g / in 3 and the MnO2 loading is 0.15 g / L (approximately 0.0025 g / in 3 ) was.

[0096] Example 2 of the present invention A particulate filter having a TWC coating and a layer of inorganic particles was prepared by repeating the same process as described in Example 1 of the present invention, and then aged at 1000° C. for 4 hours in an atmosphere of 10% water vapor in air.

[0097] Example 3 of the present invention A particulate filter having a TWC coating and a layer of inorganic particles of Al2O3 and MnO2 (10:1) was prepared by repeating the same process as described in Comparative Example 5, except that the weight ratio of alumina powder to manganese dioxide powder was 10:1. The loading of alumina in the layer of inorganic particles was 3 g / L (about 0.05 g / in 3 ) and the MnO2 loading was 0.3 g / L (approximately 0.005 g / in 3 ) was.

[0098] Example 4 of the present invention A particulate filter was prepared having a layer of inorganic particles of Al2O3 and MnO2 (5:4).

[0099] A particulate filter having a layer of inorganic particles was prepared from a filter substrate, which had a size of 132.1 mm (D) x 120 mm (L) and a volume of 1.64 L (approximately 100.4 in 3 ), a cell density of 200 cells per square inch (cpsi), a wall thickness of 8.5 mils, and a porosity of 55% as determined by mercury intrusion measurements.

[0100] A mixture of high surface area gamma alumina powder and manganese dioxide (MnO2) in a 5:4 weight ratio was mixed with a carrier gas and heated at 600 m at room temperature. 3 The alumina powder was blown into the inlet channel of the filter at a flow rate of 100000 / h. The alumina powder had a particle size D of 4.8 μm as measured by a Sympatec HELOS laser diffraction particle size analyzer. 90 The specific surface area after calcination at 1100°C for 4 hours in air (BET model, 77K nitrogen adsorption measurement) is 61m 2 The MnO2 powder was dry-milled to a particle size of 6.8 μm, D 90 It has been pre-processed.

[0101] After coating, the filter with the layer of inorganic particles in the inlet channels was calcined at a temperature of 550° C. for 1 hour. The loading of alumina in the layer of inorganic particles was 3.75 g / L (approximately 0.06 g / in 3 The loading of MnO2 was 3 g / L (approximately 0.05 g / in 3 ) was.

[0102] II.Filtration performance II.1 Back pressure Particulate filter, 600m 3 The back pressure measured by a SuperFlow SF-1020 flow bench under a cold air flow of 10000 / h was investigated.

[0103] II.2 Filtration efficiency According to the standard procedure defined in "BS EN ISO 29463-5:2018-Part 5:Test method for filter elements", 3The filtration efficiency of particulate filters in a fresh state (0 km, or unused state) was measured using di(2-ethyl-hexyl) sebacate aerosol as particles on a stationary air filter performance test bench with a cold air flow of 1000 s / h. The particle number (PN) of particles in the range of 0.10-0.15 μm was recorded by a PN counter both upstream and downstream of the tested filter. The fresh filtration efficiency (FFE) was calculated according to the following formula:

[0104]

number

[0105] The test results are summarized in the table below.

[0106] [Table 1]

[0107] A comparison between Comparative Example 1 and Reference Example 1 shows that the particulate filter with the TWC coating has a lower fresh filtration efficiency (FFE) than the blank filter, but maintains a comparable low backpressure, which may be due to the TWC component penetrating the porous walls of the particulate filter substrate.

[0108] Fresh filtration efficiency may be improved, with a tolerable increase in backpressure, by applying a layer of inorganic particles onto the porous walls of the inlet flow passages of the particulate filter substrate, as shown in Comparative Example 2.

[0109] Surprisingly, it has been found that the fresh filtration efficiency may be further improved by applying more than 2% MnO2 particles together with Al2O3 on the porous walls of the substrate of the particulate filter. The particulate filters of Examples 1 and 3 of the present invention show a fresh filtration efficiency (FFE) that is 2% higher than the particulate filter of Comparative Example 2, but the particulate filter of Comparative Example 5 does not. The 2% increase in FFE by the test method using 0.10 and 0.15 μm described above is recognized as significant in the art.

[0110] III. Exhaust removal performance The THC, CO, and NOx conversions on the particulate filters of Comparative Example 3 and Inventive Example 2 were measured on a 2.0L turbocharged gasoline engine bench through a lambda scan from 0.98 to 1.02 at a particulate filter inlet temperature of 695°C. THC, CO, and NOx concentrations were recorded both upstream and downstream of the filter being tested. THC, CO, and NOx conversions were calculated according to the following equations:

[0111]

number

[0112] The test results are summarized in the table below.

[0113] [Table 2] Conv.: Conversion

[0114] The THC, CO, and NOx conversion test results are shown in Figures 3A, 3B, and 3C, respectively. Surprisingly, it was found that the presence of MnO2 particles together with Al2O3 particles in the same layer did not have a poisoning effect on the catalytic activity of the particulate filter of Example 2 of the present invention compared to that of Comparative Example 3 which does not contain MnO2.

[0115] IV. Filter regeneration performance (soot combustion activity) Prior to measuring soot combustion activity, the particulate filters of Comparative Example 4 and Inventive Example 4 were each preloaded with approximately 7 g of soot on a 2.0 L turbocharged gasoline engine.

[0116] The soot combustion activity of the particulate filter was evaluated in a 2.0 L turbocharged gasoline engine according to the following procedure. First stage: run the engine under rich conditions at an engine speed of 2000 rpm so that the temperature rises to reach a filter inlet temperature of 600°C; Second stage: The engine was then operated under lean conditions with an air / fuel ratio (λ) of 1.05 for 75 seconds at an engine speed of 1000 rpm.

[0117] During this procedure, the inlet temperature (T-in) and bed temperature (T-bed, located 1 inch before the outlet end) of the filter were measured, as well as the O2 concentration at both the inlet (O2-in) and outlet (O2-out) of the filter. An increase in bed temperature (T-bed) indicates heat generation on the filter due to soot combustion to CO2. A decrease in O2 concentration at the outlet of the filter indicates oxygen consumption on the soot layer due to soot combustion to CO2.

[0118] The test results are summarized in the table below.

[0119] [Table 3]

[0120] The temperature measurements are shown in Figures 4A and 4B, and the oxygen consumption measurements are shown in Figures 5A and 5B.

[0121] As shown in Figure 4A, for the particulate filter of Example 4 of the present invention, a rapid temperature rise due to soot combustion was observed, but the inlet temperature (T-in) was reduced. As shown in Figure 4B, for the particulate filter of Comparative Example 4, no significant increase in bed temperature (T-bed) above 600°C was observed.

[0122] As shown in Figure 5A, for the particulate filter of Example 4 of the present invention, obvious O2 consumption was observed on the particulate filter during the second stage under lean conditions (λ = 1.05, 1000 rpm), which is attributed to soot combustion. However, as shown in Figure 5B, for the particulate filter of Comparative Example 4, no O2 consumption was observed.

[0123] It can be seen that the regeneration of a particulate filter having a layer of inorganic particles containing Al2O3 particles and MnO2 particles according to the invention can be started at a much lower temperature. It has been demonstrated that the soot combustion activity of the filter can be improved by adding MnO2 to the layer containing Al2O3 particles.

[0124] Although the invention herein has been described with reference to particular embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the invention. It will be apparent to those skilled in the art that various modifications and variations can be made to the method and apparatus of the present invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention cover modifications and variations that come within the scope of the appended claims and their equivalents.

Claims

1. It is a particulate filter, - A substrate comprising a plurality of porous walls extending longitudinally to form a plurality of balanced channels, wherein a plurality of parallel channels extend from an inlet end to an outlet end, and a certain portion of the channels are inlet channels that are open at the inlet end and closed at the outlet end, and a certain portion of the channels are outlet channels that are closed at the inlet end and open at the outlet end. - A layer of inorganic particles loaded in the inlet and / or outlet channels of the substrate, preferably at least on the surface of the porous wall in the inlet channel, A particulate filter wherein the inorganic particles include a first inorganic component selected from alumina, zirconia, ceria, silica, titania, zinc oxide, zinc carbonate, calcium oxide, calcium carbonate, silicate zeolite, aluminosilicate zeolite, or any combination thereof, and manganese oxide as a second inorganic component.

2. The particulate filter according to claim 1, wherein the first inorganic component is one or more selected from alumina, zirconia, ceria, silica, titania, zinc oxide, and rare earth metal oxides other than ceria.

3. The particulate filter according to claim 2, wherein the first inorganic component is one or more selected from alumina, zirconia, and zinc oxide.

4. The particulate filter according to claim 3, wherein the first inorganic component contains alumina or is alumina.

5. The particulate filter according to any one of claims 1 to 4, wherein the layer of inorganic particles does not exhibit ternary conversion catalytic activity.

6. The particulate filter according to any one of claims 1 to 4, wherein the layer of inorganic particles does not contain PGM components.

7. A particulate filter according to any one of claims 1 to 4, further comprising a ternary conversion catalyst (TWC) coating, preferably a wash coat containing a TWC composition.

8. The particulate filter according to claim 7, wherein the ternary conversion catalyst coating is located in at least a portion of the inlet channel and / or outlet channel of the substrate.

9. The layer of inorganic particles is 0.005 to 0.83 g / in ３ (i.e., approximately 0.3 to 50 g / L), or 0.01 to 0.33 g / in ３ (i.e., approximately 0.6–20 g / L), or 0.02–0.17 g / in ３ (i.e., approximately 1.2 to 10 g / L), or 0.025 to 0.1 g / in ３ A particulate filter according to any one of claims 1 to 4, containing in a loading amount of approximately 1.5 to 6 g / L.

10. A gasoline particulate filter according to any one of claims 1 to 4.

11. The particulate filter according to any one of claims 1 to 4, wherein the inorganic particles contain the second inorganic component in an amount of 3 to 70% or 3 to 50% based on the total weight of the inorganic particles.

12. The particulate filter according to claim 11, wherein the inorganic particles contain the second inorganic component in an amount of 3 to 15%, 4 to 12%, or 4 to 10%, based on the total weight of the inorganic particles.

13. The particulate filter according to claim 11, wherein the inorganic particles contain the second inorganic component in an amount of 40-70%, 40-50%, or 42-46% based on the total weight of the inorganic particles.

14. A method for manufacturing a particulate filter according to claim 1, - To provide a substrate that includes a plurality of porous walls extending longitudinally to form a plurality of parallel channels, wherein a certain portion of the channels are inlet channels that are open at the inlet end and closed at the outlet end, and a certain portion of the channels are outlet channels that are closed at the inlet end and open at the outlet end. A method comprising applying inorganic particles, wherein the inorganic particles comprise a first inorganic component selected from alumina, zirconia, ceria, silica, titania, zinc oxide, zinc carbonate, calcium oxide, calcium carbonate, silicate zeolite, aluminosilicate zeolite, or any combination thereof, and manganese oxide as a second inorganic component, onto the surface of the porous wall in the inlet channel and / or outlet channel of the substrate.

15. The method according to claim 14, wherein the inorganic particles are applied by a dry coating process or a wash coating process, preferably by a dry coating process.

16. The method according to claim 15, wherein the inorganic particles are applied by using the inorganic particles or their precursors.

17. An exhaust treatment system comprising a particulate filter according to any one of claims 1 to 4, or a particulate filter that can be obtained from or obtained by the method of claim 14, and positioned downstream of a gasoline engine.

18. A method for processing exhaust gas from a gasoline engine, comprising contacting the exhaust gas with a particulate filter according to any one of claims 1 to 4.

19. A method for processing an exhaust flow from a gasoline engine, comprising bringing the exhaust flow into contact with the exhaust treatment system described in Claim 17.

Images