Particulate filter

Abstract

The present invention relates to a particulate filter comprising a substrate comprising a plurality of longitudinally extending porous walls forming a plurality of parallel channels extending from an inlet end to an outlet end, wherein a number of channels are inlet channels which are open at the inlet end and closed at the outlet end, and a number of channels are outlet channels which are closed at the inlet end and open at the outlet end; and an inorganic particle layer loaded in the inlet channels and / or outlet channels, preferably on the surface of the porous walls in at least the inlet channels, wherein the inorganic particle layer comprises platy crystalline inorganic particles. The present invention further relates to a method for producing a particulate filter, an exhaust gas treatment system comprising the particulate filter and a method for treating an exhaust gas stream, in particular an exhaust gas stream from an internal combustion engine.

Description

Technical Field

[0001] This invention relates to a particulate filter, and more particularly to a particulate filter for treating exhaust gas from an internal combustion engine, the particulate filter comprising an inorganic powder particle coating. The invention also relates to an exhaust gas treatment system including the particulate filter and a method for treating exhaust gas streams, particularly those from internal combustion engines. Background Technology

[0002] Engine exhaust gases are primarily composed of gaseous pollutants such as unburned hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NOx), and particulate matter (PM). For gasoline engines, three-way catalytic converters (hereinafter interchangeably referred to as TWC catalysts or TWC) for gaseous pollutants and filters for particulate matter (PM) are well-known exhaust treatment methods to ensure that exhaust emissions comply with emission regulations, such as Euro 6 and China VI standards.

[0003] Compared to particles generated by lean-burn diesel engines, particles generated by gasoline engines (such as direct injection engines) tend to be finer and fewer in number. This is because the combustion conditions in gasoline and diesel engines differ. Additionally, the hydrocarbon composition in gasoline engine emissions differs from that of diesel engines. Particulate filters specifically designed for gasoline engines have been developed for decades to effectively treat engine exhaust gases from gasoline engines.

[0004] For example, WO 2020 / 219376A1 describes a catalytic particulate filter comprising (1) a gasoline particulate filter (GPF), (2) a main catalytic layer coated on or inside the inlet side, outlet side, or both sides of the GPF surface, the main catalytic layer comprising a first composition comprising a first carrier material and a first platinum group metal (PGM), and (3) a secondary functional material layer disposed on or inside the inlet side, outlet side, or both sides of the GPF surface, the secondary catalytic layer comprising a second composition; wherein the main catalytic layer has a higher loading than the secondary functional material layer, the secondary functional material layer is disposed on top of the main catalytic layer, or the main catalytic material layer is disposed on top of the secondary functional layer. This catalytic particulate filter, combined with an effective filter, provides improved catalytic efficiency.

[0005] WO2021 / 096841A1 describes a particulate filter for treating exhaust gas from an internal combustion engine, the particulate filter comprising (1) a particulate filter having an inlet side and an outlet side; and (2) a functional material layer coated on the inlet side, outlet side, or both sides of the particulate filter. The functional material layer comprises (1) a first inorganic material comprising one or more of alumina, zirconium oxide, cerium dioxide, silicon dioxide, titanium dioxide, and rare earth metal oxides other than cerium dioxide; and (2) a second inorganic material comprising one or more of alumina, zirconium oxide, cerium dioxide, silicon dioxide, titanium dioxide, magnesium oxide, zinc oxide, manganese oxide, silicate zeolite, and aluminosilicate zeolite.

[0006] WO2023 / 237052A1 describes a particulate filter comprising a substrate including a plurality of longitudinally extending porous walls to form a plurality of parallel channels extending from an inlet end to an outlet end, wherein a plurality of channels are inlet channels that are open at the inlet end and closed at the outlet end, and a plurality of channels are outlet channels that are closed at the inlet end and open at the outlet end; and an inorganic particle layer loaded on the surface of the porous walls in the inlet channels and / or outlet channels, wherein the inorganic particles comprise or consist of boehmite particles.

[0007] Typically, exhaust gases from gasoline engines contain a significant amount of water vapor resulting from fuel combustion. This water vapor can potentially condense and become liquid water, which can severely degrade the filtration efficiency of gasoline particulate filters, especially those with an inorganic particle layer. Original equipment manufacturers (OEMs), i.e., vehicle manufacturers, require gasoline particulate filters (GPFs) to have high filtration efficiency under low back pressure after water treatment to avoid particulate emission treatment failure due to the presence of condensate.

[0008] It is well known that the filtration performance of gasoline particulate filters improves with increasing filter life, primarily due to the accumulation of ash and soot on the filter inlet side walls. Furthermore, it has been identified that the number of emission particles generated during the cold start phase of a test cycle represents the majority of the total particles emitted during the test. Therefore, the particle filtration performance during the initial filtration phase, also known as fresh filtration efficiency, is a major focus in gasoline particulate filter performance research.

[0009] There is a need for an improved particulate filter for treating exhaust gas from internal combustion engines (particularly gasoline engines), which has improved water resistance, i.e., improved fresh filtration efficiency after water treatment. Summary of the Invention

[0010] The object of the present invention is to provide a particulate filter for treating exhaust gas from internal combustion engines, particularly gasoline engines, which has improved fresh filtration efficiency after water treatment and preferably has ideal back pressure.

[0011] Surprisingly, it has been found that the object of the present invention is achieved by a particulate filter comprising an inorganic particle layer containing plate-like crystalline particles in the filter’s inlet and / or outlet channels.

[0012] Therefore, in a first aspect, the present invention provides a particulate filter comprising:

[0013] - A substrate comprising a plurality of longitudinally extending porous walls to form a plurality of parallel channels extending from an inlet end to an outlet end, wherein a plurality of channels are inlet channels that are open at the inlet end and closed at the outlet end, and a plurality of channels are outlet channels that are closed at the inlet end and open at the outlet end; and

[0014] - An inorganic particle layer, which is loaded in the inlet channel and / or outlet channel, preferably on the surface of the porous wall in at least the inlet channel.

[0015] The inorganic particle layer contains plate-shaped crystalline inorganic particles.

[0016] In a second aspect, the present invention provides a method for producing a particulate filter, the method comprising:

[0017] - A substrate is provided, comprising a plurality of longitudinally extending porous walls to form a plurality of parallel channels extending from an inlet end to an outlet end, wherein a plurality of channels are inlet channels that are open at the inlet end and closed at the outlet end, and a plurality of channels are outlet channels that are closed at the inlet end and open at the outlet end.

[0018] - Optionally, a ternary conversion catalyst (TWC) coating is applied to the porous walls of the inlet and / or outlet channels of the substrate.

[0019] - Applying inorganic particles or their precursors to the surface of porous walls in inlet and / or outlet channels, wherein at least a portion of the inorganic particles or their precursors are plate-like crystal particles, and

[0020] -Optionally, dry and / or calcinate.

[0021] In a third aspect, the present invention provides an exhaust gas treatment system comprising a particulate filter as described in the first aspect or a particulate filter obtainable or acquireable by the method described in the second aspect, the particulate filter being located downstream of an internal combustion engine, particularly a gasoline engine.

[0022] In a fourth aspect, the present invention provides a method for treating exhaust gas from an internal combustion engine, particularly a gasoline engine, the method comprising contacting the exhaust gas with a particulate filter as described in the first aspect, a particulate filter available or obtainable from the method described in the second aspect, or an exhaust gas treatment system as described in the third aspect.

[0023] It has been found that the particulate filter according to the invention exhibits improved water resistance in terms of improved fresh filtration efficiency after water treatment, without a significant increase in back pressure. Attached Figure Description

[0024] Figure 1 An external view of a wall-flow substrate with an inlet and an outlet is shown.

[0025] Figure 2 A longitudinal cross-sectional view of an exemplary wall-flow substrate is shown, illustrating a plurality of porous walls extending longitudinally from the inlet end of the substrate to the outlet end.

[0026] Figure 3A , Figure 3B , Figure 3C and Figure 3D The XRD patterns of materials A, B, C, and D, which are used to provide inorganic particle layers in the embodiments, are shown.

[0027] Figure 4 SEM images of materials A, B, C, and D, which are used to provide inorganic particle layers in the embodiments, are shown.

[0028] Figure 5 The back pressure (BP) measured for particulate filters obtained from Examples R1, R2, R3 and R4 are shown.

[0029] Figure 6 The fresh filtration efficiency (FFE) measured for particulate filters obtained from Examples R1, R2, R3 and R4 are shown.

[0030] Figure 7 The back pressure (BP) measured for particulate filters obtained from Examples R1, R3, C1, C3, C5, C7, C9, C11, E1, E3, E5, E7, E9 and E11 are shown.

[0031] Figure 8 Fresh filtration efficiency (FFE) measured for particulate filters obtained from Examples R1, R3, C1, C3, C5, C7, C9, C11, E1, E3, E5, E7, E9 and E11 are shown.

[0032] Figure 9The back pressure (BP) measured for particulate filters obtained from Examples R2, R4, C2, C4, C6, C8, C10, C12, E2, E4, E6, E8, E10 and E12 is shown.

[0033] Figure 10 Fresh filtration efficiency (FFE) measured for particulate filters obtained from Examples R2, R4, C2, C4, C6, C8, C10, C12, E2, E4, E6, E8, E10 and E12 is shown. Detailed Implementation

[0034] The present invention will now be described in detail. It should be understood that the present invention may be embodied in many different ways and should not be construed as being limited to the embodiments set forth herein.

[0035] Unless otherwise expressly indicated by the context, the singular forms “a / an” and “the / said” include plural indicators. The terms “comprising,” “including,” etc., are used interchangeably with “containing,” etc., and are interpreted in a non-restrictive, open-ended manner. That is, for example, additional parts or elements may exist. Expressions of “consisting of” or cognates may be encompassed within “comprising” or cognates.

[0036] The term "layer," for example in the context of an inorganic particle layer, is intended to refer to a thin, breathable material coating carried on a blank or pre-coated wall of a substrate. This layer can be in the form of infill particles on the walls of the substrate, with gaps between them to allow gas permeation.

[0037] Term "D" 10 “D” 50 "and "D 90 "These have their usual meanings, referring to the diameter points in the cumulative particle size distribution where the cumulative volume reaches 10%, 50%, and 90% from the small particle diameter side. The particle size distribution is measured using a laser diffraction particle size distribution analyzer."

[0038] The term "plate-like" is intended to refer to a crystalline morphology that approximates a plate-like or sheet-like crystal having an aspect ratio of at least 3, for example, at least 5.

[0039] In the context of tabular crystals, the term "aspect ratio" refers to the ratio of the diameter to the thickness (diameter / thickness) of a tabular crystal. The aspect ratio is determined by dividing the average crystal diameter by the average crystal thickness. The average crystal diameter and average crystal thickness can be obtained by observing a number of crystals (e.g., 100 crystals) via a scanning electron microscope and averaging the individual values.

[0040] In the context of plate-like crystals, the term "crystal diameter" is intended to refer to the equivalent diameter of a circle having the same area as the main surface of the plate-like crystal (i.e., the surface perpendicular to the thickness).

[0041] The term "particles of a plate-like crystal" refers to particles that are aggregates or clusters of plate-like crystals, and may also include individual plate-like crystals.

[0042] The terms “platinum group metals (PGM) composition”, such as “palladium composition”, “platinum composition” and “rhodium composition”, are intended to describe the various platinum group metals that exist in any possible valence state, which may be, for example, metals or metal oxides as catalytically active forms, or may be, for example, metal compounds, complexes, etc., which decompose or otherwise transform into catalytically active forms upon calcination or the use of a catalyst.

[0043] The term "carrier" refers to a material in particle form used to receive and carry one or more platinum group metal (PGM) components, as well as optional one or more other components, such as stabilizers, accelerators, and binders.

[0044] In this article, any reference to " / ft 3 "or" / in 3 The references to load capacity in units are intended to indicate the weight of a specific component, coating, or layer per unit volume of the substrate or substrate portion that supports them.

[0045] According to a first aspect of the present invention, a particulate filter is provided, the particulate filter comprising:

[0046] - A substrate comprising a plurality of longitudinally extending porous walls to form a plurality of parallel channels extending from an inlet end to an outlet end, wherein a plurality of channels are inlet channels that are open at the inlet end and closed at the outlet end, and a plurality of channels are outlet channels that are closed at the inlet end and open at the outlet end; and

[0047] - An inorganic particle layer, which is loaded on the surface of the porous wall in the inlet channel and / or outlet channel.

[0048] The inorganic particle layer contains plate-shaped crystalline inorganic particles.

[0049] The substrate used in this article refers to a structure suitable for withstanding the conditions encountered in the exhaust gas flow of an internal combustion engine. It can be used as a particulate filter itself, or it can carry functional materials, such as filter improvement layers, inorganic particle layers as described herein, and any other optional layers.

[0050] The substrate comprises a plurality of longitudinally extending porous walls to form a plurality of parallel channels extending from an inlet end to an outlet end. A number of these channels are inlet channels that are open at the inlet end and closed at the outlet end, and a number of channels, different from the inlet channels, are outlet channels that are closed at the inlet end and open at the outlet end. This substrate configuration is also known as a wall-flow substrate, requiring engine exhaust gas in the inlet channels to pass through the porous walls into the outlet channels and reach the outlet end of the substrate.

[0051] Generally, the substrate can exhibit a honeycomb structure, which has alternating channels blocked by plungers at opposite ends.

[0052] The porous walls of the substrate are typically made of ceramic or metallic materials. Suitable ceramic materials for constructing the substrate can include any suitable refractory material, such as cordierite, mullite, cordierite-alumina, silicon carbide, silicon nitride, zirconium oxide, mullite, spodumene, alumina-silica-magnesium oxide, zirconium silicate, magnesium silicate, sillimanite, selenite, alumina, aluminum titanate, and aluminosilicates. Typically, the porous walls of the substrate are made of cordierite or silicon carbide.

[0053] Suitable metallic materials that can be used to construct the substrate may include heat-resistant metals and metal alloys, such as titanium and stainless steel, as well as other alloys with iron as a basic or major component. Such alloys may contain one or more of nickel, chromium, and / or aluminum, and the total amount of these metals may advantageously comprise at least 15% by weight of the alloy, for example, 10% to 25% by weight of chromium, 3% to 8% by weight of aluminum, and up to 20% by weight of nickel. The alloy may also 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 (e.g., 1000°C or higher) to form an oxide layer on the surface of the substrate, thereby improving the corrosion resistance of the alloy and promoting the adhesion of any coating to the metal surface.

[0054] The channel at the closed end is plugged with a plunger made of sealing material. Any suitable sealing material can be used without restriction.

[0055] The channels of the substrate can have any suitable cross-sectional shape and size, such as circular, elliptical, triangular, rectangular, square, hexagonal, trapezoidal, or other polygonal shapes. The substrate can have up to 700 channels (i.e., holes) per square inch of cross-section. For example, the substrate can have 100 holes / square inch to 500 holes / square inch (“cpsi”), typically 200 cpsi to 400 cpsi. The walls of the substrate can have varying thicknesses, typically ranging from 2 mils to 0.1 inches. Preferably, the substrate has an inlet channel number equal to the number of outlet channels, and the channels are uniformly distributed throughout the substrate.

[0056] Figure 1and Figure 2 A typical wall-flow substrate with multiple inlet and outlet channels is illustrated.

[0057] Figure 1 An external view of a wall-flow substrate is depicted, having an inlet end (01) from which waste gas (13) enters the substrate and an outlet end (02) from which treated waste gas exits. Alternating channels are plugged with plungers to form a checkerboard pattern at the inlet end (01) shown and a contrasting checkerboard pattern at the outlet end (02), which is not shown.

[0058] Figure 2 A longitudinal cross-sectional view of a wall-flow substrate is schematically depicted, the substrate comprising a first plurality of channels (11) opening at an inlet end (01) and closing at an outlet end (02) and a second plurality of channels (12) opening at the outlet end (02) and closing at the inlet end (01). These channels are preferably parallel to each other to form a constant wall thickness between the channels. Exhaust gas entering the first plurality of channels from the inlet end cannot leave the substrate without diffusing through the porous wall (10) into the second plurality of channels.

[0059] The particulate filter according to the invention may include an inorganic particle layer loaded on the surface of a porous wall in the inlet channel and / or outlet channel. In other words, the inorganic particle layer may be loaded solely on the porous wall in the inlet channel, solely on the porous wall in the outlet channel, or loaded on the porous walls of both the inlet and outlet channels. Specifically, the inorganic particle layer may be loaded solely on the porous wall in the inlet channel, or loaded on the porous walls of both the inlet and outlet channels, more preferably solely on the porous wall in the inlet channel.

[0060] It should be understood that the inorganic particle layer is intended to be loaded onto the surface of the porous wall in the inlet and / or outlet channels, also known as an "on-wall" coating, while a small number of inorganic particles can penetrate into the pores within the porous wall.

[0061] According to the present invention, the inorganic particles can be particles of non-PGM inorganic materials. Non-PGM inorganic materials can be, for example, alumina, hydrated alumina, boehmite, zirconium oxide, cerium dioxide, silicon dioxide, titanium dioxide, magnesium oxide, zinc oxide, zinc carbonate, calcium oxide, calcium carbonate, silicate zeolite, aluminosilicate zeolite, or any combination thereof.

[0062] Therefore, the plate-shaped inorganic particles can be plate-shaped inorganic particles selected from the following non-PGM inorganic materials: alumina, hydrated alumina, boehmite, zirconium oxide, cerium dioxide, silicon dioxide, titanium dioxide, magnesium oxide, zinc oxide, zinc carbonate, calcium oxide, calcium carbonate, silicate zeolite, aluminosilicate zeolite, or any combination thereof.

[0063] Preferably, the inorganic particles, particularly the plate-like crystalline inorganic particles, are particles selected from the following non-PGM inorganic materials: alumina, hydrated alumina, boehmite, silica, zinc oxide, zirconium oxide, or any combination thereof, more preferably selected from alumina, boehmite, or any combination thereof.

[0064] The inorganic particle layer may optionally contain PGM components, such as palladium and / or platinum components. The PGM components (if present) may be loaded onto the particles of the plate-like crystal as described above, or may exist separately from the particles of the plate-like crystal.

[0065] In this paper, the inorganic particle layer loaded on the porous walls of the inlet and / or outlet channels of the substrate specifically refers to a layer that exhibits little or no, preferably no, TWC activity, but may exhibit some catalytic activity if the inorganic particles contain one or more PGM components.

[0066] In some embodiments, the inorganic particle layer does not contain PGM components. Preferably, the inorganic particle layer may consist primarily or substantially of plate-like crystals of non-PGM inorganic materials selected from alumina, hydrated alumina, boehmite, zirconium oxide, cerium dioxide, silicon dioxide, titanium dioxide, magnesium oxide, zinc oxide, zinc carbonate, calcium oxide, calcium carbonate, silicate zeolite, aluminosilicate zeolite, or any combination thereof, wherein alumina, hydrated alumina, boehmite, silicon dioxide, zinc oxide, zirconium oxide, or any combination thereof are preferred, and alumina, boehmite, or any combination thereof are more preferred.

[0067] In this document, any reference to “mainly composed of” in the context of an inorganic particle layer is intended to indicate that the inorganic particle layer contains a major amount, i.e., more than 50 vol% of the specified plate-shaped crystalline inorganic particles, which may be, for example, 75 vol% or more, 85 vol% or more, 90 vol% or more, or even 95 vol% or more.

[0068] In this document, any reference to “consisting substantially of” in the context of an inorganic particle layer is intended to mean that the inorganic particle layer contains an unintentionally added amount of inorganic particles other than the specified plate-shaped crystalline inorganic particles. In this document, the term “unintentionally added amount” is intended to mean no more than 1% by volume, no more than 0.5% by volume, no more than 0.1% by volume, or no more than 0.05% by volume.

[0069] The inventors have discovered that the plate-like crystal morphology of inorganic particles has a beneficial effect on the water resistance of particulate filters.

[0070] As measured by scanning electron microscopy (SEM), plate-like crystals may have an average crystal diameter of no more than 20 micrometers (μm), no more than 10 μm, no more than 5 μm, or no more than 3 μm.

[0071] As measured by scanning electron microscopy (SEM), plate-like crystals may have an average crystal thickness of no more than 1000 nanometers (nm), no more than 500 nm, or no more than 300 nm.

[0072] In some embodiments, the plate-like crystal may have an average crystal diameter of no more than 10 µm and an average crystal thickness of no more than 1000 nm, preferably no more than 5 µm and no more than 500 nm, and more preferably no more than 3 µm and no more than 300 nm.

[0073] The plate-like crystals preferably have an aspect ratio (diameter / thickness ratio) of not more than 100, for example, not more than 50, not more than 30, not more than 20, or not more than 15. In particular, the plate-like crystals have an aspect ratio in the range of 3 to 50, 3 to 30, or 3 to 20. Alternatively, the plate-like crystals have an aspect ratio in the range of 5 to 50, 5 to 30, or 5 to 20, especially 5 to 15.

[0074] There are no particular restrictions on the geometry of plate-like crystals. The main surface of a plate-like crystal, that is, the surface perpendicular to its thickness, can have an irregular shape or a regular shape, such as circles, ellipses, and polygons, such as triangles, quadrilaterals, and hexagons.

[0075] The inorganic particles that can be used in this invention, especially plate-shaped crystalline inorganic particles, may have a density (D) of not more than 30 micrometers (μm), not more than 15 μm, or not more than 10 μm. 90 The inorganic particles that can be used in this invention, particularly plate-shaped crystalline inorganic particles, may have a density (D) in the range of 1 μm to 20 μm, 1 μm to 10 μm, or 1 μm to 5 μm. 50 The inorganic particles that can be used in this invention, especially plate-shaped crystalline inorganic particles, may have a density (D) of not more than 8 μm, not more than 5 μm, or not more than 2 μm. 10 .

[0076] The inorganic particles that can be used in this invention, particularly plate-shaped crystalline inorganic particles, as determined by nitrogen adsorption, can have a particle size of not more than 150 μm. 2 / g, preferably not more than 100m 2 / g of BET surface area.

[0077] Additionally or alternatively, the inorganic particles used in this invention, particularly plate-shaped crystalline inorganic particles, as determined by nitrogen adsorption, may have a particle size not exceeding 0.5 cm.3 / g, not greater than 0.3cm 3 / g or not greater than 0.2cm 3 / g BET pore volume.

[0078] The particulate filter according to the present invention may have a loading capacity of 0.016 g / in. 3 Up to 3.28g / in 3 (i.e., approximately 1 g / L to 200 g / L), 0.03 g / in 3 Up to 1.64 g / in 3 (i.e., approximately 2 g / L to 100 g / L) or 0.08 g / in 3 Up to 0.82g / in 3 (i.e., an inorganic particle layer of approximately 5 g / L to 50 g / L).

[0079] Inorganic particle layers can be applied to the surface of a porous wall substrate using any known process, such as dry coating and washcoating.

[0080] Dry coating processes are well-known and generally involve blowing inorganic particles, in particulate form or suitable precursors, into channels of a substrate from an open end via a carrier gas flow, and optionally drying and calcining the coated substrate. This process eliminates the use of liquid carriers. The inorganic particles are typically distributed in the form of a particle bed on the surface of the porous walls of the channels.

[0081] It should be understood that after calcination of the coated substrate, the applied inorganic particles or their suitable precursors will retain their crystalline morphology. In other words, calcination (if performed) will not cause a change in the crystalline morphology of the inorganic particles.

[0082] In some implementations, inorganic particles or suitable precursors may be blown into the inlet channel from the open end toward the closed end. The particle bed formed in the inlet channel may be located on the porous wall of the inlet channel and also opposite a plunger blocking the channel. The particle bed, i.e., the layer of inorganic particles, is permeable, which may help capture particulate matter (PM) in the exhaust gas stream and allow gaseous pollutants in the exhaust gas stream to permeate through.

[0083] The inorganic particle layer in the form of a particle bed can extend along the porous wall of the channel that loads the inorganic particles. It should be understood that the particle bed can extend along the entire length of the porous wall of the channel, or only along a portion of the length of the porous wall of the channel.

[0084] Wash-coating is also well known and is generally performed by applying a slurry containing inorganic particles or suitable precursors thereof and optional additives in a liquid solvent (e.g., water) from an open end into a channel of a substrate, followed by drying and optionally calcining the coated substrate. The inorganic particle layer applied by wash-coating can be in the form of a porous coating that can extend along the porous walls of the channel carrying the inorganic particles. Alternatively, the porous coating can extend along the entire length of the porous walls of the channel or only along a portion of the length of the porous walls of the channel.

[0085] The particulate filter according to the invention may optionally, but preferably, include a TWC coating in the inlet and / or outlet channels of the substrate. In particular, the TWC coating is present in both the inlet and outlet channels of the substrate.

[0086] TWC coatings are typically in the form of wash-out coatings containing a TWC composition, also known as "in-wall" coatings. TWC coatings may extend along the entire length of the porous wall of the channel, or only along a portion of the length of the porous wall of the channel.

[0087] It should be understood that the TWC coating is intended to be loaded into the pores of the porous walls of the channel, while a considerable amount of TWC composition can also be found on the surface of the porous walls in the coated channel.

[0088] There are no particular limitations on the TWC compositions that can be used for TWC coatings contained in particulate filters. Typically, TWC compositions contain a platinum group metal component as the catalytically active material, such as a rhodium component supported on a support particle, and one or both of a platinum and palladium component. Available materials used as the support can be refractory metal oxides, oxygen storage components, and any combination thereof.

[0089] Examples of refractory metal oxides may include, but are not limited to, aluminum oxide, lanthanum oxide-doped aluminum oxide, barium oxide-doped aluminum oxide, cerium dioxide-doped aluminum oxide, zirconium oxide-doped aluminum oxide, cerium dioxide-zirconia oxide-doped aluminum oxide, lanthanum oxide-zirconia oxide-doped aluminum oxide, barium oxide-lanthanum oxide-doped aluminum oxide, barium oxide-cerium dioxide-doped aluminum oxide, barium oxide-zirconia oxide-doped aluminum oxide, barium oxide-lanthanum oxide-neodymium oxide-doped aluminum oxide, lanthanum oxide-cerium dioxide-doped aluminum oxide, and any combination thereof.

[0090] Examples of oxygen storage components (OSCs) may include, but are not limited to, reducible rare earth metal oxides, such as cerium dioxide. The oxygen storage component may also comprise one or more of lanthanum oxide, praseodymium oxide, neodymium oxide, europium oxide, samarium oxide, ytterbium oxide, yttrium oxide, zirconium oxide, and hafnium oxide to form a composite oxide with cerium dioxide. In particular, the oxygen storage component is selected from cerium dioxide-zirconia composite oxides and stable cerium dioxide-zirconia composite oxides.

[0091] The particulate filter according to the present invention may include a loading capacity of 0.1 g / in. 3 Up to 5.0g / in 3 (i.e., 6.1 g / L to 305.1 g / L) or 0.5 g / in 3 Up to 3.0g / in 3 (i.e., 30.5 g / L to 183.1 g / L) or 0.8 g / in 3 Up to 2g / in 3 (i.e., 49 g / L to 122 g / L) of TWC coating.

[0092] Based on the corresponding PGM elements, the TWC coating can contain a total loading of 1.0 g / ft. 3 Up to 50.0 g / ft 3 (i.e., 0.04 g / L to 1.8 g / L) or 5.0 g / ft 3 Up to 20.0 g / ft 3 (i.e., 0.18 g / L to 0.71 g / L) of PGM components.

[0093] TWC coatings can be applied to a substrate using any known process (typically a wash-coating process). A wash-coating process generally involves coating the substrate with a slurry containing TWC catalyst particles with supported PGM components and optional additives in a solvent (e.g., water), drying, and calcining the coated substrate.

[0094] When present, the TWC coating is applied to the substrate prior to the loaded inorganic particle layer as described above. When present, the TWC coating can also be referred to as the undercoat, i.e., it lies beneath the inorganic particle layer.

[0095] In some exemplary embodiments, the particulate filter according to the invention comprises:

[0096] - A substrate comprising a plurality of longitudinally extending porous walls forming a plurality of parallel channels extending from an inlet end to an outlet end, wherein a plurality of channels are inlet channels that are open at the inlet end and closed at the outlet end, and a plurality of channels are outlet channels that are closed at the inlet end and open at the outlet end; and

[0097] - An inorganic particle layer, which is loaded on the surface of the porous wall in at least the inlet channel, and

[0098] - Optional TWC coating, preferably a wash-out coating comprising a TWC composition,

[0099] The inorganic particle layer contains plate-shaped crystalline inorganic particles.

[0100] In a further exemplary embodiment, the particulate filter according to the invention comprises:

[0101] - A substrate comprising a plurality of longitudinally extending porous walls forming a plurality of parallel channels extending from an inlet end to an outlet end, wherein a plurality of channels are inlet channels that are open at the inlet end and closed at the outlet end, and a plurality of channels are outlet channels that are closed at the inlet end and open at the outlet end; and

[0102] - An inorganic particle layer, which is loaded on the surface of the porous wall in at least the inlet channel, and

[0103] -Optional wash coating containing TWC composition,

[0104] The inorganic particle layer contains plate-shaped crystalline inorganic particles in amounts of 75% or higher, 85% or higher, 90% or higher, or even 95% or higher of the total volume of all inorganic particles in the inorganic particle layer.

[0105] In some other exemplary embodiments, the particulate filter according to the invention comprises:

[0106] - A substrate comprising a plurality of longitudinally extending porous walls to form a plurality of parallel channels extending from an inlet end to an outlet end, wherein a plurality of channels are inlet channels that are open at the inlet end and closed at the outlet end, and a plurality of channels are outlet channels that are closed at the inlet end and open at the outlet end; and

[0107] - An inorganic particle layer, which is loaded on the surface of the porous wall in at least the inlet channel, and

[0108] -Optional wash coating containing TWC composition,

[0109] The inorganic particle layer is basically composed of plate-shaped crystalline inorganic particles of non-PGM inorganic materials.

[0110] In some other exemplary embodiments, the particulate filter according to the invention comprises:

[0111] - A substrate comprising a plurality of longitudinally extending porous walls to form a plurality of parallel channels extending from an inlet end to an outlet end, wherein a plurality of channels are inlet channels that are open at the inlet end and closed at the outlet end, and a plurality of channels are outlet channels that are closed at the inlet end and open at the outlet end; and

[0112] - An inorganic particle layer, which is loaded on the surface of the porous wall in at least the inlet channel, and

[0113] -Optional wash coating containing TWC composition,

[0114] The inorganic particle layer is mainly or essentially composed of plate-shaped crystalline inorganic particles of non-PGM inorganic materials selected from alumina, hydrated alumina, boehmite, silica, zinc oxide, zirconium oxide, or any combination thereof.

[0115] In some specific embodiments, the particulate filter according to the present invention comprises:

[0116] - A substrate comprising a plurality of longitudinally extending porous walls to form a plurality of parallel channels extending from an inlet end to an outlet end, wherein a plurality of channels are inlet channels that are open at the inlet end and closed at the outlet end, and a plurality of channels are outlet channels that are closed at the inlet end and open at the outlet end; and

[0117] - An inorganic particle layer, which is loaded on the surface of the porous wall in at least the inlet channel, and

[0118] -Optional wash coating containing TWC composition,

[0119] The inorganic particle layer is mainly or substantially composed of inorganic particles of non-PGM inorganic materials selected from alumina, hydrated alumina, boehmite, silica, zinc oxide, zirconium oxide or any combination thereof, and wherein the plate-like crystals have an aspect ratio in the range of 5 to 50, 5 to 30 or 5 to 20, particularly 5 to 15.

[0120] In some preferred embodiments, the particulate filter according to the invention comprises:

[0121] - A substrate comprising a plurality of longitudinally extending porous walls to form a plurality of parallel channels extending from an inlet end to an outlet end, wherein a plurality of channels are inlet channels that are open at the inlet end and closed at the outlet end, and a plurality of channels are outlet channels that are closed at the inlet end and open at the outlet end; and

[0122] - An inorganic particle layer, which is loaded on the surface of the porous wall in at least the inlet channel, and

[0123] -Optional wash coating containing TWC composition,

[0124] The inorganic particle layer is mainly or substantially composed of inorganic particles of non-PGM inorganic materials selected from alumina, hydrated alumina, boehmite, silica, or any combination thereof, and wherein the plate-like crystals have an aspect ratio in the range of 5 to 20 or 5 to 15.

[0125] In each of the exemplary and specific embodiments described above, it is preferred that the plate-like crystal has an average crystal diameter of no more than 10 µm and an average crystal thickness of no more than 1000 nm, preferably no more than 5 µm and no more than 500 nm, and more preferably no more than 3 µm and no more than 300 nm.

[0126] In each of the exemplary and specific embodiments described above, it is preferred that the inorganic particles consist essentially of plate-like crystalline inorganic particles having at least one, preferably all, of the following particle size characteristics.

[0127] - D not greater than 15μm 90 ,

[0128] D from -1μm to 10μm 50 ,and

[0129] - D not greater than 5μm 10 .

[0130] More preferably, the inorganic particles are essentially composed of plate-shaped crystalline inorganic particles having at least one of the following particle size characteristics, preferably all of them.

[0131] - D not greater than 10μm 90 ,

[0132] D from -1μm to 5μm 50 ,and

[0133] - D not greater than 2μm 10 .

[0134] In the exemplary and specific embodiments described above, it is preferred that the inorganic particle layer does not contain PGM components.

[0135] In the exemplary and specific embodiments described above, it is preferred that the particulate filter includes a wash coating comprising a TWC composition.

[0136] The particulate filter can be housed in a housing having an inlet and an outlet for exhaust gas flow, which can be operationally associated with and in fluid communication with other parts of the engine's exhaust system.

[0137] According to a second aspect of the present invention, a method for producing a particulate filter is provided, the method comprising:

[0138] - A substrate is provided comprising a plurality of longitudinally extending porous walls to form a plurality of parallel channels extending from an inlet end to an outlet end, wherein a plurality of channels are inlet channels that are open at the inlet end and closed at the outlet end, and a plurality of channels are outlet channels that are closed at the inlet end and open at the outlet end.

[0139] - Applying inorganic particles or their precursors to the surface of porous walls in inlet and / or outlet channels, wherein at least a portion of the inorganic particles or their precursors are plate-like crystal particles, and

[0140] -Optionally, dry and / or calcinate.

[0141] Inorganic particles can be applied to the surface of porous walls by a dry coating or wash-coating process (preferably a dry coating process) as described in the first aspect above.

[0142] In some embodiments, the method for producing a particulate filter further includes applying a TWC coating to the porous walls of the substrate in the inlet and / or outlet channels before applying inorganic particles to the surface of the porous walls. The TWC coating can be applied by a wash-coating process as described above.

[0143] Any general description and preferred requirements of the inorganic particle layer and TWC coating in the first aspect above may be applied herein by reference.

[0144] In some embodiments, the applied inorganic particles, greater than 50% by volume, such as 75% by volume or higher, 85% by volume or higher, 90% by volume or higher, or even 95% by volume or higher, are the plate-like crystalline inorganic particles specified herein. In particular, the applied inorganic particles consist essentially of plate-like crystalline inorganic particles.

[0145] According to a third aspect, an exhaust gas treatment system is provided, the exhaust gas treatment system including the particulate filter described in the first aspect or the particulate filter that can be obtained or acquired from the method described in the second aspect, the particulate filter being located downstream of a gasoline engine.

[0146] According to a fourth aspect, a method for treating exhaust gas from a gasoline engine is provided, the method comprising contacting the exhaust gas with a particulate filter as described in the first aspect, a particulate filter available or obtainable from the method described in the second aspect, or an exhaust gas treatment system as described in the third aspect.

[0147] Implementation Plan

[0148] Various embodiments are listed below. It should be understood that the embodiments listed below can be combined with all aspects of the invention and other embodiments.

[0149] Implementation Scheme 1. A particulate filter, the particulate filter comprising

[0150] - A substrate comprising a plurality of longitudinally extending porous walls to form a plurality of parallel channels extending from an inlet end to an outlet end, wherein a plurality of the channels are inlet channels that are open at the inlet end and closed at the outlet end, and a plurality of the channels are outlet channels that are closed at the inlet end and open at the outlet end; and

[0151] - An inorganic particle layer, said inorganic particle layer being loaded in the inlet channel and / or the outlet channel, preferably on the surface of the porous wall in at least the inlet channel.

[0152] The inorganic particle layer contains plate-shaped crystalline inorganic particles.

[0153] Implementation Scheme 2. The particulate filter according to Implementation Scheme 1, wherein the inorganic particle layer comprises 50% or more, 75% or more, 85% or more, 90% or more, or even 95% or more of the plate-shaped crystalline inorganic particles.

[0154] Implementation Scheme 3. The particulate filter according to Implementation Scheme 2, wherein the inorganic particle layer is substantially composed of the plate-shaped crystalline inorganic particles.

[0155] Implementation Scheme 4. The particulate filter according to any one of the foregoing implementation schemes, wherein the inorganic particle layer exhibits no ternary conversion catalytic activity.

[0156] Implementation Scheme 5. The particulate filter according to any one of the foregoing embodiments, wherein the inorganic particle layer does not contain PGM components.

[0157] Implementation Scheme 6. The particulate filter according to any one of the foregoing embodiments, wherein the inorganic particles, particularly the plate-like crystalline inorganic particles, are particles specifically selected from the following non-PGM inorganic materials: alumina, hydrated alumina, boehmite, zirconium oxide, cerium dioxide, silicon dioxide, titanium dioxide, magnesium oxide, zinc oxide, zinc carbonate, calcium oxide, calcium carbonate, silicate zeolite, aluminosilicate zeolite, or any combination thereof.

[0158] Implementation Scheme 7. The particulate filter according to Implementation Scheme 6, wherein the non-PGM inorganic material is selected from alumina, hydrated alumina, boehmite, silica, zinc oxide, zirconium oxide or any combination thereof, preferably alumina, boehmite or a combination thereof.

[0159] Implementation Scheme 8. The particulate filter according to any one of the preceding embodiments, wherein, as measured by scanning electron microscopy (SEM), the plate-like crystals have an average crystal diameter of not more than 20 μm, not more than 10 μm, not more than 5 μm, or not more than 3 μm.

[0160] Implementation Scheme 9. The particulate filter according to any one of the preceding embodiments, wherein, as measured by scanning electron microscopy (SEM), the plate-like crystals have an average crystal thickness of not more than 1000 nm, not more than 500 nm, or not more than 300 nm.

[0161] Implementation Scheme 10. The particulate filter according to any one of the preceding embodiments, wherein the plate-like crystals have an aspect ratio of at least 3, for example, at least 5.

[0162] Implementation Scheme 11. The particulate filter according to any one of the preceding implementation schemes, wherein the plate-shaped crystals have an aspect ratio of not more than 100, for example not more than 50, not more than 30, not more than 20 or not more than 15.

[0163] Implementation Scheme 12. The particulate filter according to any one of the foregoing embodiments, the particulate filter further comprising a ternary conversion catalyst (TWC) coating, preferably a wash-out coating comprising a TWC composition.

[0164] Implementation Scheme 13. The particulate filter according to Implementation Scheme 12, wherein the ternary conversion catalyst coating is located in the inlet channel and / or the outlet channel of the substrate.

[0165] Implementation Scheme 14. The particulate filter according to any one of the preceding embodiments, the particulate filter comprising the inorganic particle layer with a loading of 1 g / L to 200 g / L, 2 g / L to 100 g / L, or 5 g / L to 50 g / L.

[0166] Implementation Scheme 15. The particulate filter according to any one of the foregoing implementation schemes, wherein the particulate filter is a gasoline particulate filter.

[0167] Implementation Scheme 16. A method for producing a particulate filter according to any one of Implementation Schemes 1 to 15, the method comprising:

[0168] - A substrate is provided, the substrate comprising a plurality of longitudinally extending porous walls to form a plurality of parallel channels extending from an inlet end to an outlet end, wherein a plurality of the channels are inlet channels that are open at the inlet end and closed at the outlet end, and a plurality of the channels are outlet channels that are closed at the inlet end and open at the outlet end.

[0169] Optionally, a ternary conversion catalyst (TWC) coating is applied to the porous walls of the inlet channel and / or outlet channel of the substrate.

[0170] - Applying inorganic particles or their precursors to the surface of the porous walls in the inlet channel and / or the outlet channel, wherein at least a portion of the inorganic particles or their precursors are plate-like crystal particles, and

[0171] -Optionally, dry and / or calcinate.

[0172] Implementation Scheme 17. The method according to Implementation Scheme 16, wherein the inorganic particles are applied by a dry coating or wash-coating process, preferably by a dry coating process.

[0173] Implementation Scheme 18. An exhaust gas treatment system comprising a particulate filter according to any one of embodiments 1 to 15 or a particulate filter obtainable or acquireable from the method according to any one of embodiments 16 to 17, and located downstream of a gasoline engine.

[0174] Implementation Scheme 19. A method for treating exhaust gas from a gasoline engine, the method comprising contacting the exhaust gas with a particulate filter according to any one of embodiments 1 to 15, a particulate filter available or obtainable from the method according to any one of embodiments 16 to 17, or an exhaust gas treatment system according to embodiment 18.

[0175] Example

[0176] The invention is illustrated more fully by way of the following examples, which are set forth in order to illustrate certain aspects of the invention and should not be construed as limiting the invention.

[0177] I. Materials and Characterization

[0178] Materials A through D, the powders used in the examples to prepare the inorganic particle layer in the particulate filter, are summarized in Table 1.

[0179] Particle size was measured using a Malvern 3000 laser diffraction particle size analyzer.

[0180] Surface area and pore volume were measured using a Micromeritics ASAP 2420 surface area and porosity analyzer with a BET model at 77 K nitrogen adsorption.

[0181] X-ray diffraction (XRD) scans were performed using a Bruker D8 Advance. The XRD patterns of materials A through D are shown in [the diagram / image / etc.]. Figures 3A to 3DThe study confirmed that materials A and C are alumina, while materials B and D are boehmite.

[0182] SEM images of the material are shown in Figure 4 The study confirmed that materials A and B are aggregates of non-plate-shaped small particles, while materials C and D are particles of plate-shaped crystals.

[0183] Table 1

[0184]

[0185] II. Preparation of Particulate Filters

[0186] Example R1

[0187] A cordierite substrate for a gasoline particulate filter was used as a reference filter (blank filter), measuring 132.1 mm (D) × 101.6 mm (L) with a volume of 1.4 L (approximately 85.4 in). 3 The pore density is 300 pores per square inch (cpsi), the wall thickness is 8 mils, and the porosity is 65%, as determined by mercury porosimetry.

[0188] Example R2

[0189] Provide blank filters after water treatment.

[0190] The blank filter, identical to that in Example R1, was placed horizontally in water at a depth of 2 cm for 10 minutes. Then, the blank filter was dried at 200°C for 4 hours.

[0191] Example R3

[0192] A particulate filter with a TWC coating was prepared from the same filter substrate as the blank filter of Example R1 by applying a TWC coating to both the inlet and outlet channels of the blank filter.

[0193] In a planetary mixer (P-mixer), 14.05 g of a 9.67 wt% rhodium nitrate aqueous solution was impregnated onto 594 g of high surface area γ-alumina powder to form a wet powder, simultaneously achieving initial moisture content. Also in a planetary mixer (P-mixer), 27.61 g of a 16.39 wt% diethanolamine hexahydroxyplatinate aqueous solution was impregnated onto 1609 g of cerium dioxide / zirconium oxide (40% cerium dioxide) composite powder to form a wet powder, simultaneously achieving initial moisture content. An aqueous slurry was formed by mixing the two wet powders with 2086 g of deionized water, to which 181 g of barium nitrate and 151 g of a 21.6 wt% zirconium nitrate aqueous solution were added. The pH of the slurry was adjusted to 3.6 with nitric acid. The slurry was then ground to a particle size D.90 The coating thickness was 4.5 μm. Then, a 50% wash coating load was applied to the inlet and outlet channels of the blank filter, and the remaining 50% wash coating load was applied to the outlet channel of the blank filter. The coated substrate was then dried at 150°C for 1 hour, and then calcined at 550°C for 1 hour.

[0194] The obtained in-wall TWC coating has a content of approximately 1.47 g / in. 3 (90 g / L) of wash coating loading and approximately 6.5 g / ft 3 The total PGM load is 0.23 g / L, and the Pt / Rh ratio is 5 / 1.5.

[0195] Example R4

[0196] We provide particulate filters with a TWC coating after water treatment.

[0197] The same particulate filter as in Example R3 is subjected to water treatment as described in Example R2.

[0198] Example C1

[0199] Prepare a particulate filter with a TWC coating and an inorganic particle layer.

[0200] First, a particulate filter with a TWC coating was prepared using the same process as in Example R3. Then, material A (non-plate-shaped alumina particles) was mixed with a carrier gas and subjected to a reaction at 600 m³ / h at room temperature. 3 A flow rate of 3 g / L (0.049 g / in) is blown into the inlet channel of the filter. The loading of material A is 3 g / L (0.049 g / in). 3 ).

[0201] Example C2

[0202] Provides particulate filters with TWC coating and inorganic particle layer after water treatment.

[0203] The same particulate filter as in Example C1 is subjected to water treatment as described in Example R2.

[0204] Example C3

[0205] Prepare a particulate filter with a TWC coating and an inorganic particle layer.

[0206] The particulate filter was prepared using the same process as in Example C1, except that the loading of material A was 5 g / L (0.082 g / in). 3 ).

[0207] Example C4

[0208] Provides particulate filters with TWC coating and inorganic particle layer after water treatment.

[0209] The same particulate filter as in Example C3 was subjected to water treatment as described in Example R2.

[0210] Example C5

[0211] Prepare a particulate filter with a TWC coating and an inorganic particle layer.

[0212] The particulate filter was prepared using the same process as in Example C1, except that the loading of material A powder was 7 g / L (0.115 g / in). 3 ).

[0213] Example C6

[0214] Provides particulate filters with TWC coating and inorganic particle layer after water treatment.

[0215] The same particulate filter as that prepared in Example C5 was subjected to water treatment as described in Example R2.

[0216] Example C7

[0217] Prepare a particulate filter with a TWC coating and an inorganic particle layer.

[0218] First, a particulate filter with a TWC coating was prepared using the same process as in Example R3. Then, material B (non-plate-like boehmite particles) was mixed with a carrier gas and discharged at 600 m at room temperature. 3 A flow rate of 1 g / L is blown into the inlet channel of the filter. The loading of material B is 1 g / L (0.016 g / in). 3 ).

[0219] Example C8

[0220] Provides particulate filters with TWC coating and inorganic particle layer after water treatment.

[0221] The same particulate filter as in Example C7 is subjected to water treatment as described in Example R2.

[0222] Example C9

[0223] Prepare a particulate filter with a TWC coating and an inorganic particle layer.

[0224] The particulate filter was prepared using the same process as in Example C7, except that the loading of material B was 3 g / L (0.049 g / in).3 ).

[0225] Example C10

[0226] Provides particulate filters with TWC coating and inorganic particle layer after water treatment.

[0227] The same particulate filter as in Example C9 is subjected to water treatment as described in Example R2.

[0228] Example C11

[0229] Prepare a particulate filter with a TWC coating and an inorganic particle layer.

[0230] The particulate filter was prepared using the same process as in Example C7, except that the loading of material B powder was 5 g / L (0.082 g / in). 3 ).

[0231] Example C12

[0232] Provides particulate filters with TWC coating and inorganic particle layer after water treatment.

[0233] The same particulate filter as that prepared in Example C11 was subjected to water treatment as described in Example R2.

[0234] Example E1

[0235] Prepare a particulate filter with a TWC coating and an inorganic particle layer.

[0236] First, a particulate filter with a TWC coating was prepared using the same process as in Example R3. Then, material C (plate-like crystalline alumina particles) was mixed with a carrier gas and heated at 600 m³ / h at room temperature. 3 A flow rate of 10 g / L (0.164 g / in) is blown into the inlet channel of the filter. The loading of material C is 10 g / L (0.164 g / in). 3 ).

[0237] Example E2

[0238] Provides particulate filters with TWC coating and inorganic particle layer after water treatment.

[0239] The same particulate filter as in Example E1 is subjected to water treatment as described in Example R2.

[0240] Example E3

[0241] Prepare a particulate filter with a TWC coating and an inorganic particle layer.

[0242] The particulate filter was prepared using the same process as in Example E1, except that the loading of material C was 15 g / L (0.246 g / in3).

[0243] Example E4

[0244] Provides particulate filters with TWC coating and inorganic particle layer after water treatment.

[0245] The same particulate filter as in Example E3 is subjected to water treatment as described in Example R2.

[0246] Example E5

[0247] Prepare a particulate filter with a TWC coating and an inorganic particle layer.

[0248] The particulate filter was prepared using the same process as in Example E1, except that the loading of material C was 20 g / L (0.328 g / in). 3 ).

[0249] Example E6

[0250] Provides particulate filters with TWC coating and inorganic particle layer after water treatment.

[0251] The same particulate filter as in Example E5 is subjected to water treatment as described in Example R2.

[0252] Example E7

[0253] Prepare a particulate filter with a TWC coating and an inorganic particle layer.

[0254] First, a particulate filter with a TWC coating was prepared using the same process as in Example R3. Then, material D (plate-like boehmite particles) was mixed with a carrier gas and heated at 600 m at room temperature. 3 A flow rate of 10 g / L (0.164 g / in) is blown into the inlet channel of the filter. The loading of material D powder is 10 g / L (0.164 g / in). 3 ).

[0255] Example E8

[0256] Provides particulate filters with TWC coating and inorganic particle layer after water treatment.

[0257] The same particulate filter as in Example E7 is subjected to water treatment as described in Example R2.

[0258] Example E9

[0259] Prepare a particulate filter with a TWC coating and an inorganic particle layer.

[0260] The particulate filter was prepared using the same process as in Example E7, except that the loading of material D powder was 15 g / L (0.246 g / in). 3 ).

[0261] Example E10

[0262] Provides particulate filters with TWC coating and inorganic particle layer after water treatment.

[0263] The same particulate filter as in Example E9 is subjected to water treatment as described in Example R2.

[0264] Example E11

[0265] Prepare a particulate filter with a TWC coating and an inorganic particle layer.

[0266] The particulate filter was prepared using the same process as in Example E7, except that the loading of material D powder was 20 g / L (0.328 g / in). 3 ).

[0267] Example E12

[0268] Provides particulate filters with TWC coating and inorganic particle layer after water treatment.

[0269] The same particulate filter as in Example E11 is subjected to water treatment as described in Example R2.

[0270] III. Filtration performance

[0271] III.1 Back Pressure (BP)

[0272] Back pressure (BP) studies were conducted on the particulate filters of all embodiments, such as using a SuperFlow SF-1020 Flowbench at 600m. 3 The measurement was taken under a cold air flow of / h.

[0273] III.2 Fresh Filtration Efficiency (FFE)

[0274] According to the standard procedure defined in "ВS ENISО 29463-5:2018 – Part 5: Test method for filter elements", in a 600m 3On a fixed air filter performance test bench with a cold air flow of / h, using aerosol di(2-ethylhexyl) sebacate as particles, the filtration efficiency of the particulate filters of all embodiments was measured in a fresh state (0km or open box state). The particle number (PN) of particles ranging from 0.10µm to 0.15µm was recorded by PN counters both upstream and downstream of the test filter. The fresh filtration efficiency (FFE) was calculated according to the following equation.

[0275]

[0276] The test results for each particulate filter are summarized in Table 2 below.

[0277] Table 2

[0278]

[0279] To better understand the benefits of the inorganic particle layer of plate-like crystals to filter performance, the particulate filters of all embodiments will be divided into three groups.

[0280] Group I

[0281] This group includes the particulate filters of embodiments R1, R2, R3, and R4. The back pressure (BP) and fresh filtration efficiency (FFE) of these particulate filters are shown in [the table / formula]. Figure 5 and Figure 6 middle.

[0282] The back pressure (BP) of the blank filter and the TWC-coated particle filter was found to be stable before and after water treatment, while the fresh filtration efficiency (FFE) of the blank filter decreased from 70% to 62% after water treatment, and the FFE of the TWC-coated particle filter decreased from 62% to 59% (R1 vs. R2, and R3 vs. R4).

[0283] Group II

[0284] This group includes particulate filters of embodiments R1, R3, C1, C3, C5, C7, C9, C11, E1, E3, E5, E7, E9, and E11. The back pressure (BP) and fresh filtration efficiency (FFE) of these particulate filters are shown in [the table / formula missing]. Figure 7 and Figure 8 middle.

[0285] A comparison between Example R1 and Example R3 shows that the particulate filter with the TWC coating has a higher back pressure (BP) and a lower fresh filtration efficiency (FFE) compared to the blank filter. This is likely because the TWC component penetrates into the porous walls of the particulate filter substrate. By applying an inorganic particle layer to the porous walls of the inlet channel of the substrate, the fresh filtration efficiency of the particulate filter is improved, while the increase in back pressure is acceptable, as shown by the comparison between Example R3 and Examples C1, C3, C5, C7, C9, C11, E1, E3, E5, E7, E9, and E11.

[0286] Group III

[0287] This group includes examples R2, R4, C2, C4, C6, C8, C10, C12, E2, E4, E6, E8, E10, and E12. The back pressure (BP) and fresh filtration efficiency (FFE) of these particulate filters are shown in [the table / formula missing]. Figure 9 and Figure 10 middle.

[0288] It was found that the FFE of all particulate filters with a TWC coating and an inorganic material A or B (i.e., non-plate-like particles) layer decreased to about 60% after water treatment, returning to the same level as the particulate filter with only a TWC coating (Example R4). The beneficial effect of the inorganic particle layer on the FFE of the particulate filter was completely lost.

[0289] Surprisingly, all particulate filters with a TWC coating and an inorganic material C or D (i.e., plate-like crystalline particle) layer maintained a relatively high FFE (at least 72%). Notably, the beneficial effects of the inorganic particle layer on the particulate filter's FFE were partially retained. With the plate-like crystalline inorganic particle layer, the particulate filter exhibited significantly improved fresh filtration efficiency and acceptable back pressure after water treatment.

[0290] Although the invention has been described herein with reference to specific 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 methods and apparatus of the invention without departing from the spirit and scope of the invention. Therefore, the invention is intended to include modifications and variations within the scope of the appended claims and their equivalents.

Claims

1. A particulate filter, the particulate filter comprising: - A substrate comprising a plurality of longitudinally extending porous walls to form a plurality of parallel channels extending from an inlet end to an outlet end, wherein a plurality of the channels are inlet channels that are open at the inlet end and closed at the outlet end, and a plurality of the channels are outlet channels that are closed at the inlet end and open at the outlet end; and - An inorganic particle layer, said inorganic particle layer being loaded in the inlet channel and / or the outlet channel, preferably on the surface of the porous wall in at least the inlet channel. The inorganic particle layer comprises plate-shaped crystalline inorganic particles.

2. The particulate filter of claim 1, wherein the inorganic particle layer comprises 50% or more, 75% or more, 85% or more, 90% or more, or even 95% or more of the plate-like crystalline inorganic particles.

3. The particulate filter according to claim 2, wherein the inorganic particle layer is substantially composed of the plate-like crystalline inorganic particles.

4. The particulate filter according to any one of the preceding claims, wherein the inorganic particle layer exhibits no ternary conversion catalytic activity.

5. The particulate filter according to any one of the preceding claims, wherein the inorganic particle layer does not contain PGM components.

6. The particulate filter according to any one of the preceding claims, wherein the inorganic particles, particularly the plate-like crystalline inorganic particles, are particles specifically selected from the following non-PGM inorganic materials: alumina, hydrated alumina, boehmite, zirconium oxide, cerium dioxide, silicon dioxide, titanium dioxide, magnesium oxide, zinc oxide, zinc carbonate, calcium oxide, calcium carbonate, silicate zeolite, aluminosilicate zeolite, or any combination thereof.

7. The particulate filter according to claim 6, wherein the non-PGM inorganic material is selected from alumina, hydrated alumina, boehmite, silica, zinc oxide, zirconium oxide, or any combination thereof, preferably alumina, boehmite, or a combination thereof.

8. The particulate filter according to any one of the preceding claims, wherein the plate-like crystals have an average crystal diameter of not more than 20 μm, not more than 10 μm, not more than 5 μm, or not more than 3 μm, as measured by scanning electron microscopy (SEM).

9. The particulate filter according to any one of the preceding claims, wherein, as measured by scanning electron microscopy (SEM), the plate-like crystals have an average crystal thickness of not more than 1000 nm, not more than 500 nm, or not more than 300 nm.

10. The particulate filter according to any one of the preceding claims, wherein the plate-like crystals have an aspect ratio of at least 3, for example, at least 5.

11. The particulate filter according to any one of the preceding claims, wherein the plate-like crystals have an aspect ratio of not more than 100, for example not more than 50, not more than 30, not more than 20 or not more than 15.

12. The particulate filter according to any one of the preceding claims, wherein the particulate filter further comprises a ternary conversion catalyst (TWC) coating, preferably comprising a wash-out coating of a TWC composition.

13. The particulate filter of claim 12, wherein the ternary conversion catalyst coating is located in the inlet channel and / or the outlet channel of the substrate.

14. The particulate filter according to any one of the preceding claims, wherein the particulate filter comprises the inorganic particle layer having a loading of 1 g / L to 200 g / L, 2 g / L to 100 g / L, or 5 g / L to 50 g / L.

15. The particulate filter according to any one of the preceding claims, wherein the particulate filter is a gasoline particulate filter.

16. A method for producing a particulate filter according to any one of claims 1 to 15, the method comprising: - A substrate is provided, the substrate comprising a plurality of longitudinally extending porous walls to form a plurality of parallel channels extending from an inlet end to an outlet end, wherein a plurality of the channels are inlet channels that are open at the inlet end and closed at the outlet end, and a plurality of the channels are outlet channels that are closed at the inlet end and open at the outlet end. Optionally, a ternary conversion catalyst (TWC) coating is applied to the porous walls of the inlet channel and / or outlet channel of the substrate. - Applying inorganic particles or their precursors to the surface of the porous walls in the inlet channel and / or the outlet channel, wherein at least a portion of the inorganic particles or their precursors are plate-like crystal particles, and -Optionally, dry and / or calcinate.

17. The method of claim 16, wherein the inorganic particles are applied by a dry coating or wash-coating process, preferably by a dry coating process.

18. An exhaust gas treatment system comprising a particulate filter according to any one of claims 1 to 15 or a particulate filter obtainable or acquireable by the method according to any one of claims 16 to 17, and located downstream of a gasoline engine.

19. A method for treating exhaust gas from a gasoline engine, the method comprising contacting the exhaust gas with a particulate filter according to any one of claims 1 to 15, a particulate filter available or obtainable by the method according to any one of claims 16 to 17, or an exhaust gas treatment system according to claim 18.

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