Catalytic particulate filter

Abstract

The present invention relates to a 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 number of channels are inlet channels open at the inlet end and closed at the outlet end, the inlet ends of the outlet channels are closed, and the outlet ends of the outlet channels are open; and an in-wall TWC coating in the inlet channel and the outlet channel, the in-wall TWC coating comprising a platinum group metal component, an alumina-based refractory metal oxide, and an oxygen storage component wherein the weight ratio of the alumina-based refractory metal oxide to the oxygen storage component of the in-wall TWC coating is in the range of from 1: 20 to 1: 3, and wherein the in-wall TWC coating does not contain any separate zirconium and barium species. The invention also relates to a gasoline engine emission treatment system comprising the catalytic particulate filter and a method for treating exhaust gas from a gasoline engine.

Description

Technical Field

[0001] The present invention relates to a catalyzed particulate filter for treating exhaust gas from a gasoline engine, the catalyzed particulate filter comprising an in-wall TWC coating. The present invention also relates to a gasoline engine emission treatment system comprising a catalyzed particulate filter and a method for treating exhaust gas from a gasoline engine. Background Art

[0002] Engine exhaust gas is basically composed of gaseous pollutants (such as unburned hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx)) and particles. For gasoline engines, a three-way conversion catalyst (hereinafter interchangeably referred to as a TWC catalyst or TWC) for gaseous pollutants and a filter for particles are well-known post-treatment means to ensure that exhaust emissions comply with regulations.

[0003] As is known in the art, particles generated by gasoline engines (such as direct injection engines) tend to be finer and less numerous than particles generated by diesel lean-burn engines. This is because the combustion conditions of gasoline engines are different from those of diesel engines. Particle filters (also called gasoline particulate filters) for treating exhaust gas from gasoline engines have been developed for decades to effectively treat exhaust gas, and among these particulate filters, catalytic gasoline particulate filters having a combined catalytic activity and filtering function have attracted high interest.

[0004] WO 2018 / 024547A1 describes a catalytic particle filter comprising a three-way conversion (TWC) catalytic material that penetrates the particle filter wall. Coating the TWC catalytic material on or in the filter may result in back pressure effects. A special coating scheme is proposed in this patent application to avoid excessive increase in back pressure while providing full three-way conversion functionality. The coated porosity of the catalytic particle filter is required to be less than the uncoated porosity of the particle filter.

[0005] WO 2017 / 109514A1 describes a catalytic wall-flow monolith for use in an emission treatment system, wherein the monolith comprises a porous substrate and a TWC catalyst, wherein the TWC catalyst is substantially distributed throughout the porous substrate, and wherein the TWC catalyst comprises (i) alumina; (ii) one or more platinum group metals; and (iii) an oxygen storage component (OSC), wherein the OSC comprises ceria or one or more mixed oxides comprising cerium and is present in a weight ratio of OSC to alumina of 65:35 to 85:15.

[0006] WO 2020 / 200394 A1 describes a particle filter comprising a wall flow filter of length L and two catalytically active coatings Y and Z, wherein the wall flow filter comprises channels E and A, which extend in parallel between a first end and a second end of the wall flow filter and are formed into surfaces O, respectively. E and O A The particle filter is characterized in that the coating Y is located on the surface O E The coating Z is located on the surface O in the channel E and extends from the first end of the wall flow filter over 55% to 90% of the length L. A The invention relates to a wall-flow filter having a plurality of coatings Y and Z. The plurality of coatings Y and Z are provided in a channel A on the wall-flow filter and extend from the second end of the wall-flow filter over 55% to 90% of the length L, and the coatings Y and Z contain alumina in an amount of 20% to 70% by weight relative to the total weight of the coating Y or Z, rhodium, palladium, or palladium and rhodium in an amount of 30% to 80% by weight relative to the total weight of the coating Y or Z, and one or more oxygen storage components.

[0007] WO2020 / 200398A1 describes a particulate filter for removing particles, carbon monoxide, hydrocarbons and nitrogen oxides from the exhaust gas of an internal combustion engine operating with a stoichiometric air / fuel mixture, the particulate filter comprising a wall flow filter of length L and two different coatings Y and Z, wherein the wall flow filter comprises channels E and A, channels E and A extend in parallel between a first end and a second end of the wall flow filter and are separated by a porous wall forming a surface OE or OA, and wherein channel E is closed at the second end and channel A is closed at the first end, characterized in that the two coatings Y and Z are located in the porous wall and extend from the first end of the wall flow filter over the entire length L and both comprise activated alumina, at least one oxygen storage material and at least one platinum group metal.

[0008] As gaseous and particulate emissions from gasoline engines become more strictly regulated (eg, Euro 6 and China 6), vehicle manufacturers, ie, original equipment manufacturers (OEMs), require catalyzed gasoline particulate filters that have high catalytic activity at low back pressure.

[0009] It would be desirable to provide an improved catalyzed gasoline particulate filter having higher catalytic activity and exhibiting lower back pressure. Summary of the invention

[0010] An object of the present invention is to provide a catalyzed particulate filter for treating exhaust gases from a gasoline engine, the catalyzed particulate filter having improved catalytic performance. Another object of the present invention is to provide a particulate filter for treating exhaust gases from a gasoline engine, the catalyzed particulate filter having improved catalytic performance and exhibiting lower back pressure.

[0011] It has surprisingly been found that the objects of the present invention are achieved by a particle filter comprising an intra-wall TWC coating containing a platinum group metal component and an alumina-based refractory metal oxide and an OSC at a low alumina / oxygen storage component (OSC) ratio and being free of separate zirconium and barium species.

[0012] Therefore, in a first aspect, the present invention provides a particle 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 number of the channels are inlet channels open at the inlet end and closed at the outlet end, and a number of the channels are outlet channels closed at the inlet end and open at the outlet end; and

[0014] - an in-wall ternary conversion (TWC) coating in the inlet and outlet channels, the coating comprising a platinum group metal component, a refractory metal oxide based on alumina and an oxygen storage component (OSC),

[0015] wherein the weight ratio of the alumina-based refractory metal oxide to the oxygen storage component of the in-wall TWC coating is in the range of 1:20 to 1:3, and

[0016] The TWC coating inside the wall does not contain any separate zirconium or barium substance.

[0017] In a second aspect, the present invention provides a method for producing a particle filter as described herein, the method comprising the steps of:

[0018] - providing a slurry, comprising mixing a platinum group metal component or a precursor thereof, an alumina-based refractory metal oxide and an oxygen storage component in a solvent, wherein the platinum group metal is not pre-fixed on the alumina-based refractory metal oxide and the oxygen storage component prior to the mixing,

[0019] as well as

[0020] - Apply the slurry into the inlet and outlet channels of the substrate

[0021] To form a TWC coating inside the wall.

[0022] In a third aspect, the invention provides an exhaust gas treatment system comprising a particle filter as described in the first aspect, preferably a particle filter obtainable from or obtainable by the method as described in the second aspect, the particle filter being located downstream of a gasoline engine.

[0023] In a fourth aspect, the present invention provides a method for treating exhaust gas from a gasoline engine, the method comprising contacting the exhaust gas with a particulate filter as described in the first aspect, preferably a particulate filter obtainable from or obtained by the method as described in the second aspect, or an exhaust gas treatment system as described in the third aspect.

[0024] It has been found that the particle filter according to the present invention can provide improved catalytic performance compared to prior art counterparts.In addition, improved back pressure characteristics are observed for gasoline particle filters. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 An exterior view of an exemplary wall flow substrate having an inlet end and an outlet end is schematically depicted.

[0026] Figure 2 A longitudinal cross-sectional view of an exemplary wall-flow substrate having a plurality of porous walls extending longitudinally from an inlet end to an outlet end of the substrate is schematically depicted.

[0027] Figure 3 A longitudinal cross-sectional view of an exemplary in-wall TWC coating configuration of a gasoline particulate filter according to the present invention is schematically depicted. DETAILED DESCRIPTION

[0028] The present invention is described in detail 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.

[0029] The singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. The terms "comprising", "including", and the like are used interchangeably with "containing", and are to be interpreted in a non-limiting, open-ended manner. That is, for example, additional components or elements may be present. The expression "consisting of" or cognates may be encompassed by "comprising" or cognates.

[0030] In this context, reference to "free of" is intended to mean that the substances mentioned in its context are not intentionally added or used. However, it will be understood by those skilled in the art that trace amounts of substances may be present as impurities derived from those components intentionally used.

[0031] In this document, the term "intra-wall" in the context of a TWC coating is intended to mean a TWC coating in which the TWC component is intentionally loaded into the pores of the porous wall of the substrate, but a small amount, e.g., less than 50 wt%, preferably less than 30 wt%, more preferably less than 10 wt%, of the TWC component may be present on the surface of the porous wall in the coating channel. The meaning of the term "intra-wall" is known in the art, e.g., as described in WO2017 / 109514A.

[0032] Terms of platinum group metal component, such as "palladium component", "platinum component" and "rhodium component" are intended to describe the presence of the corresponding platinum group metal in any possible valence state, which may be, for example, the metal or metal oxide as a catalytically active form.

[0033] In this article, any reference to "g / ft 3” or g" / in 3 Any reference to loading in units of "is intended to mean the weight of a particular component, coating or layer per unit volume of the substrate that carries the particular component, coating or layer.

[0034] According to a first aspect of the present invention, there is provided a particle filter, the particle filter comprising:

[0035] - 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 number of the channels are inlet channels open at the inlet end and closed at the outlet end, and a number of the channels are outlet channels closed at the inlet end and open at the outlet end; and

[0036] - an in-wall ternary conversion (TWC) coating in the inlet and outlet channels, the coating comprising a platinum group metal component, a refractory metal oxide based on alumina and an oxygen storage component (OSC),

[0037] wherein the weight ratio of the alumina-based refractory metal oxide to the oxygen storage component of the in-wall TWC coating is in the range of 1:20 to 1:3, and

[0038] The TWC coating inside the wall does not contain any separate zirconium or barium substance.

[0039] As used herein, a substrate refers to a structure suitable for withstanding the conditions encountered in the exhaust flow of an internal combustion engine and can function alone as a particulate filter, on which one or more functional coatings, such as a catalytically active coating (such as a TWC coating as described herein) and any other coatings can be carried.

[0040] The substrate includes 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 number of the channels are inlet channels that are open at the inlet end and closed at the outlet end, and a number of the channels other than the inlet channels are outlet channels that are closed at the inlet end and open at the outlet end. The configuration of the substrate requires that the engine exhaust gas in the inlet channel flows through the porous walls into the outlet channel to the outlet end of the substrate, which is also referred to as a "wall flow" substrate.

[0041] Generally speaking, the substrate may have a honeycomb structure with alternating channels plugged with plugs at opposite ends.

[0042] The porous wall of the substrate is generally made of ceramic material or metal material.

[0043] Suitable ceramic materials that can be used to construct the substrate can include any suitable refractory material, such as cordierite, mullite, cordierite-alumina, silicon carbide, silicon nitride, zirconium oxide, mullite, spodumene, alumina-silicon dioxide-magnesia, zirconium silicate, magnesium silicate, sillimanite, petalite, alumina, aluminum titanate and aluminosilicate. Typically, the porous wall of the substrate is made of cordierite or silicon carbide.

[0044] Suitable metal materials that can be used to construct substrates can include heat-resistant metals and metal alloys, such as titanium and stainless steel and other alloys with iron as the basic or main component. Such alloys can contain one or more of nickel, chromium and / or aluminum, and the total amount of these metals can advantageously include at least 15% by weight of the alloy, such as 10% by weight to 25% by weight of chromium, 3% by weight to 8% by weight of aluminum and up to 20% by weight of nickel. The alloy may also contain a small amount or trace of one or more metals, such as manganese, copper, vanadium, titanium, etc. The surface of the metal substrate can 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.

[0045] The channel is closed at the closed end with a plug of sealing material. Any suitable sealing material may be used without any particular limitation.

[0046] The channels of the substrate can have any suitable cross-sectional shape and size, such as circular, elliptical, sinusoidal, triangular, rectangular, square, hexagonal, trapezoidal or other polygonal shapes. The substrate can have up to 700 channels (i.e., holes) / square inch of cross section. For example, the substrate can have 100 holes / square inch to 500 holes / square inch ("cpsi"), typically with 200cpsi to 400cpsi. The walls of the substrate can have different thicknesses, with a typical range of 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 evenly distributed throughout the substrate.

[0047] Typically, the porous walls of the substrate may have an average pore size in the range of 10 to 30 micrometers (μm), for example 13 to 25 μm or 15 to 21 μm.

[0048] Figure 1 and Figure 2 A typical wall-flow substrate comprising a plurality of inlet channels and outlet channels is illustrated.

[0049] Figure 1 Schematically depicts an external view of a wall-flow substrate having an inlet end (01) from which an exhaust gas stream (13) enters the substrate and an outlet end (02) from which a treated exhaust gas stream (14) exits. Alternating channels are plugged with plungers to form a checkerboard pattern at the inlet end (01) shown and an opposing checkerboard pattern at the outlet end (02) not shown.

[0050] Figure 2 A longitudinal cross-sectional view of a wall-flow substrate is schematically depicted, the wall-flow substrate comprising a first plurality of channels (11) opening at an inlet end (01) and closed at an outlet end (02) and a second plurality of channels (12) opening at the outlet end (02) and closed at the inlet end (01). The channels are preferably parallel to each other to form a constant wall thickness between the channels. The exhaust gas flow (13) entering the first plurality of channels (11) from the inlet end must diffuse through the porous wall (10) into the second plurality of channels to exit the substrate as a treated flow (14).

[0051] The in-wall TWC coating exists in both the inlet channel and the outlet channel, which may also be referred to as the in-wall TWC coating in the inlet channel and the in-wall TWC coating in the outlet channel.

[0052] In some embodiments, the in-wall TWC coating in the inlet channel extends from the inlet end of the channel along 50% to 100% of the axial length of the inlet channel; and the in-wall TWC coating in the outlet channel extends from the outlet end of the channel along 50% to 100% of the axial length of the outlet channel.

[0053] Preferably, the in-wall TWC coating in the inlet channel and the in-wall TWC coating in the outlet channel each extend along 50% to 75%, more preferably 50% to 60%, most preferably 50% to 55% of the axial length of the respective channel.

[0054] It should be understood that the inner wall TWC coating in the inlet channel and the inner wall TWC coating in the outlet channel may overlap each other in length. Figure 3 Schematically depicts the Figure 1 and Figure 2A longitudinal cross-section of such an in-wall TWC coating configuration on a substrate is shown, wherein the in-wall TWC coating (15) in the inlet channel and the in-wall TWC coating (16) in the outlet channel extend with a certain overlapping length.

[0055] In some specific embodiments, the inner wall TWC coating in the inlet channel and the inner wall TWC coating in the outlet channel extend over respective lengths, with the overlap length not exceeding 10 mm.

[0056] Preferably, there are no layers of TWC components on the surface of the substrate wall, except for those optionally present in the overlapping regions of the TWC coating within the walls in the inlet and outlet channels.

[0057] For the purposes of the present invention, the wall-inside TWC coating in the inlet channel and the wall-inside TWC coating in the outlet channel preferably have the same composition. More preferably, the wall-inside TWC coating in the inlet channel and the wall-inside TWC coating in the outlet channel are contained in the particle filter at the same or substantially the same loading. In this context, the term "substantially the same loading" is intended to mean that the difference between the loading of the wall-inside TWC coating in the inlet channel and the loading of the wall-inside TWC coating in the outlet channel is less than 20%, in particular less than 10%, preferably less than 5%, more preferably 1%, as calculated based on the lower of the two loadings.

[0058] There is no particular limitation on the platinum group metal (PGM) component contained in the in-wall TWC coating. Generally, the PGM component may be a platinum (Pt) component, a palladium (Pd) component, a rhodium (Rh) component, a ruthenium (Ru) component, an osmium (Os) component, an iridium (Ir) component, or any combination thereof, wherein the Pt component, the Pd component, the Rh component, or any combination thereof is particularly useful.

[0059] In some embodiments, the in-wall TWC coating comprises a combination of a Rh component, a Pt component, and an optional Pd component as a PGM component. In particular, the in-wall TWC coating comprises a combination of a Rh component and a Pt component as a PGM component.

[0060] In-wall TWC coatings can contain a total loading of 1.0 g / ft 3 Up to 50.0g / ft 3 (i.e. about 0.04 g / L to 1.8 g / L) or 5.0 g / ft 3 Up to 20.0g / ft 3 (i.e., about 0.18 g / L to 0.71 g / L) of PGM components, calculated as the corresponding PGM elements.

[0061] Preferably, the Rh component is present in the intra-wall TWC coating in an amount of 5% to 70%, preferably 10% to 60%, more preferably 20% to 50%, relative to the total loading of the PGM component.

[0062] As used herein, the term "alumina-based refractory metal oxide" refers to an oxide material comprising optionally doped alumina, and encompasses alumina itself and doped alumina.

[0063] Suitable examples of alumina-based refractory metal oxides include, but are not limited to, high surface area aluminas such as gamma alumina or a mixture of gamma and delta aluminas which may also contain significant amounts of η, κ, and θ alumina phases; and doped aluminas such as lanthanum oxide doped aluminas, barium oxide doped aluminas, ceria doped aluminas, zirconia doped aluminas, ceria-zirconia doped aluminas, lanthanum oxide-zirconia doped aluminas, barium oxide-lanthanum oxide doped aluminas, barium oxide-lanthanum oxide-neodymium oxide doped aluminas, and any combination thereof.

[0064] In some embodiments, the alumina-based refractory metal oxide in the in-wall TWC coating is selected from alumina, lanthanum oxide-doped alumina, lanthanum oxide-doped alumina, ceria-doped alumina, zirconia-doped alumina, ceria-doped alumina, or any combination thereof, more preferably alumina, lanthanum oxide-doped alumina, or a combination thereof.

[0065] As is well known, an oxygen storage component (OSC) refers to an entity that has multiple valence states and can react actively with an oxidant (such as oxygen or nitrogen oxides) under oxidizing conditions or with a reducing agent (such as carbon monoxide (CO) or hydrogen) under reducing conditions. Typically, the OSC can be a reducible rare earth metal oxide such as ceria, or a composite oxide of ceria with one or more of lanthanum oxide, praseodymium oxide, neodymium oxide, europium oxide, samarium oxide, ytterbium oxide, yttrium oxide, zirconium oxide and hafnium oxide, preferably a composite oxide of ceria with one or more of lanthanum oxide, praseodymium oxide, neodymium oxide, yttrium oxide and zirconium oxide. Preferably, the oxygen storage component is selected from ceria, ceria-zirconia composite oxides and rare earth stabilized ceria-zirconia composite oxides. It should be understood that the term "composite oxide" in the context of OSC does not cover physical mixtures of ceria with one or more other oxides.

[0066] In the inner wall TWC coating, the weight ratio of the alumina-based refractory metal oxide to the oxygen storage component is in the range of 1:20 to 1:3, preferably 1:15 to 1:4, more preferably 1:10 to 1:5, most preferably 1:10 to 1:7, for example 1:9 and 1:8 or any ratio therebetween. The inventors have surprisingly found that the ratio of the alumina-based refractory metal oxide to the oxygen storage component in the inner wall TWC coating in the above range contributes to the excellent catalytic performance of the particle filter according to the present invention. If the ratio is lower than 1:20 or higher than 1:3, the catalytic performance of the particle filter will deteriorate.

[0067] The inventors have also surprisingly found that the absence of any separate zirconium species and barium species in the in-wall TWC coating can contribute to the excellent catalytic performance of the particulate filter according to the present invention. In this context, separate zirconium species and barium species refer to zirconium species and barium species that are present as separate components, as can be determined by scanning electron microscope-energy dispersive spectrometer (SEM-EDS) analysis. In other words, the in-wall TWC coating does not contain any zirconium species and barium species, except for those optionally contained in the alumina-based refractory metal oxide or the oxygen storage component.

[0068] The zirconium material may be any zirconium compound, such as zirconium oxide, a zirconium salt, or a combination thereof. The barium material may be any barium compound, such as barium oxide, a barium salt, or a combination thereof.

[0069] In some exemplary embodiments, the particle filter according to the present invention comprises:

[0070] - 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 number of the channels are inlet channels open at the inlet end and closed at the outlet end, and a number of the channels are outlet channels closed at the inlet end and open at the outlet end; and

[0071] - an in-wall ternary conversion (TWC) coating in the inlet and outlet channels, the coating comprising a platinum group metal component, a refractory metal oxide based on alumina and an oxygen storage component (OSC),

[0072] wherein the alumina-based refractory metal oxide is selected from alumina, alumina doped with lanthanum oxide, alumina doped with lanthanum oxide-zirconia, alumina doped with ceria, alumina doped with zirconia, alumina doped with ceria-zirconia, or any combination thereof, and the oxygen storage component is selected from ceria or a composite oxide of ceria with one or more of lanthanum oxide, praseodymium oxide, neodymium oxide, europium oxide, samarium oxide, ytterbium oxide, yttrium oxide, zirconium oxide, and hafnium oxide,

[0073] wherein the weight ratio of the alumina-based refractory metal oxide to the oxygen storage component of the in-wall TWC coating is in the range of 1:15 to 1:4, and

[0074] The TWC coating inside the wall does not contain any separate zirconium or barium substance.

[0075] In the above exemplary embodiments, the weight ratio of the alumina-based refractory metal oxide to the oxygen storage component is preferably in the range of 1:10 to 1:5, more preferably 1:10 to 1:7.

[0076] In some other exemplary embodiments, the particle filter according to the present invention comprises:

[0077] - 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 number of the channels are inlet channels open at the inlet end and closed at the outlet end, and a number of the channels are outlet channels closed at the inlet end and open at the outlet end; and

[0078] - an in-wall ternary conversion (TWC) coating in the inlet and outlet channels, the coating comprising a platinum group metal component, a refractory metal oxide based on alumina and an oxygen storage component (OSC),

[0079] The alumina-based refractory metal oxide is selected from alumina, alumina doped with lanthanum oxide or a combination thereof, and the oxygen storage component is selected from a composite oxide of cerium dioxide and one or more of lanthanum oxide, praseodymium oxide, neodymium oxide, yttrium oxide and zirconium oxide.

[0080] wherein the weight ratio of the alumina-based refractory metal oxide to the oxygen storage component of the in-wall TWC coating is in the range of 1:15 to 1:4, and

[0081] The TWC coating inside the wall does not contain any separate zirconium or barium substance.

[0082] Preferably, the particle filter according to the present invention comprises:

[0083] - 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 number of the channels are inlet channels open at the inlet end and closed at the outlet end, and a number of the channels are outlet channels closed at the inlet end and open at the outlet end; and

[0084] - an in-wall ternary conversion (TWC) coating in the inlet and outlet channels, the coating comprising a platinum group metal component, a refractory metal oxide based on alumina and an oxygen storage component (OSC),

[0085] The alumina-based refractory metal oxide is selected from alumina, alumina doped with lanthanum oxide or a combination thereof, and the oxygen storage component is selected from a composite oxide of cerium dioxide and one or more of lanthanum oxide, praseodymium oxide, neodymium oxide, yttrium oxide and zirconium oxide.

[0086] wherein the weight ratio of the alumina-based refractory metal oxide to the oxygen storage component of the in-wall TWC coating is in the range of 1:10 to 1:5, and

[0087] The TWC coating inside the wall does not contain any separate zirconium or barium substance.

[0088] More preferably, the particle filter according to the present invention comprises:

[0089] - 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 number of the channels are inlet channels open at the inlet end and closed at the outlet end, and a number of the channels are outlet channels closed at the inlet end and open at the outlet end; and

[0090] - an in-wall ternary conversion (TWC) coating in the inlet and outlet channels, the coating comprising a platinum group metal component, a refractory metal oxide based on alumina and an oxygen storage component (OSC),

[0091] The alumina-based refractory metal oxide is selected from alumina, alumina doped with lanthanum oxide or a combination thereof, and the oxygen storage component is selected from a composite oxide of cerium dioxide and one or more of lanthanum oxide, praseodymium oxide, neodymium oxide, yttrium oxide and zirconium oxide.

[0092] wherein the weight ratio of the alumina-based refractory metal oxide to the oxygen storage component of the in-wall TWC coating is in the range of 1:10 to 1:7, and

[0093] The TWC coating inside the wall does not contain any separate zirconium or barium substance.

[0094] The particle filter according to the present invention may include a particle loading of 0.1 g / in 3 Up to 5.0g / in 3 (i.e. about 6.1 g / L to 305.1 g / L), or 0.5 g / in 3 Up to 3.0g / in 3 (i.e. about 30.5 g / L to 183.1 g / L), or 0.8 g / in 3 Up to 2g / in 3 (ie, about 49 g / L to 122 g / L) of TWC coating within the wall.

[0095] The particulate filter may be housed within a housing having an inlet and an outlet for exhaust flow, which housing may be operatively associated with and in fluid communication with the rest of the engine's exhaust system.

[0096] The in-wall TWC coating can be applied to the substrate by any known process, for example by a conventional washcoating process, which includes applying a slurry of the TWC components into the channels of the substrate. The PGM components are usually pre-fixed to support particles such as alumina-based refractory metal oxides by impregnation and / or heat treatment and then formulated into a solvent. It is believed that pre-fixation can prevent some deactivation of the PGM components, which can be observed when in contact with alumina-based refractory metal oxides.

[0097] However, the inventors surprisingly discovered that a particulate filter comprising an intra-wall TWC coating (applied by washcoating a slurry prepared without pre-fixing the PGM component on a support) can provide significantly reduced exhaust emissions compared to a particulate filter comprising an intra-wall TWC coating (applied by washcoating a slurry prepared by pre-fixing the PGM component on a support).

[0098] Therefore, in a second aspect, the present invention provides a method for producing a particle filter according to the first aspect of the present invention, the method comprising:

[0099] - providing a slurry, comprising mixing a platinum group metal component or a precursor thereof, an alumina-based refractory metal oxide and an oxygen storage component in a solvent, wherein the platinum group metal is not pre-fixed on the alumina-based refractory metal oxide and the oxygen storage component prior to the mixing,

[0100] as well as

[0101] - Apply the slurry into the inlet and outlet channels of the substrate

[0102] To form a TWC coating inside the wall.

[0103] As used herein, the terms "pre-fixed" and "pre-fixing" in the context of platinum group metals (PGMs) are intended to refer to PGMs that have been attached to a support (such as an alumina-based refractory metal oxide or an oxygen storage component), for example, by impregnation (e.g., incipient wetness impregnation) and / or heat treatment.

[0104] Typically, the slurry may be provided by mixing a platinum group metal component or a precursor thereof, an alumina-based refractory metal oxide, and an oxygen storage component in a suitable solvent, such as water, to which additives such as promoters, binders, stabilizers, viscosity modifiers, pH modifiers, surfactants, or any combination thereof may be added. Prior to mixing the platinum group metal component or a precursor thereof, the alumina-based refractory metal oxide, and the oxygen storage component, the platinum group metal is not pre-fixed on the alumina-based refractory metal oxide and the oxygen storage component. This method for providing the slurry may also be referred to as a one-pot process.

[0105] In some specific embodiments of the method for producing a particulate filter, a slurry may be provided by mixing a Pt component or a precursor thereof and an oxygen storage component in a solvent, to which an alumina-based refractory metal oxide is added, and then an Rh component or a precursor thereof is added. Alternatively, a slurry may be provided by mixing an Rh component or a precursor thereof with an alumina-based refractory metal oxide in a solvent, to which an oxygen storage component is added, and then a Pt component or a precursor thereof is added. In those embodiments, there is no particular limitation on the timing of mixing the additives (if used).

[0106] Suitable precursors of the platinum group metal component are, for example, soluble salts and / or complexes of platinum group metals, such as ammine complex salts, hydroxyl salts, nitrates, carboxylates and ammonium salts, oxides and colloids of platinum group metals.

[0107] The components used to provide the slurry can be used in conventional forms, such as powders, sols or solutions or suspensions in solvents. The solvent can be the same solvent as the solvent of the slurry, in particular water. The slurry applied to the substrate can have a conventional solids content, such as 15% to 60% by weight.

[0108] It should be understood that if an additive is used in the slurry, the additive will not be any zirconium-containing material or barium-containing material. By avoiding the use of such zirconium-containing materials or barium-containing materials in the slurry, an in-wall TWC coating without any separate zirconium and barium materials as described in the first aspect of the present invention can be provided.

[0109] If necessary, the slurry may be crushed / milled before application to the substrate to provide a suitable particle size for the wall coating. For example, the slurry may have a D of less than 10 micrometers (μm), such as 7 μm or less, preferably 5 μm or less. 90 Preferably, the slurry has a D greater than 0.4 micrometers (μm), for example 1 μm or greater, preferably 2 μm or greater. 90 The comminution / grinding can be accomplished in any conventional equipment, such as a ball mill, a continuous Eiger mill, and the like.

[0110] The slurry generally has a pH of 2 to less than 9. If necessary, an inorganic or organic acid and / or base may be used as a pH adjuster.

[0111] The slurry can be applied to the substrate by immersing the substrate in the slurry, or by coating it on the substrate in other ways, so that the desired loading amount of the coating will be deposited on the substrate wall. If necessary, conventional means such as blowing, applying vacuum, etc., can be used to remove excess slurry from the substrate (especially the slurry remaining on the wall surface). Thereafter, the coated substrate can be dried at a temperature in the range of 100°C to 300°C and / or calcined at a temperature in the range of 350°C to 650°C for a period of time, for example, 1 hour to 3 hours. Drying and calcining are usually carried out in air. If necessary, the coating process, drying process and calcining process can be repeated to achieve the final desired weight amount of the TWC coating on the substrate. The loading amount of the TWC coating can be determined by calculating the weight difference between the substrate before coating and the substrate coated after calcination.

[0112] It will be appreciated that any features generally or preferably described above for the in-wall TWC coating of the particle filter of the first aspect are applicable herein to the method according to the second aspect.

[0113] The particle filter according to the first aspect or produced by the method according to the second aspect is particularly suitable for treating exhaust gases from gasoline engines.

[0114] Thus, in a third aspect, the invention provides an exhaust gas treatment system comprising a particle filter as described in the first aspect, preferably a particle filter obtainable or obtainable by the method as described in the second aspect, the particle filter being located downstream of a gasoline engine.

[0115] In a fourth aspect, the present invention provides a method for treating exhaust gas from a gasoline engine, the method comprising contacting the exhaust gas with a particulate filter as described in the first aspect, a particulate filter obtainable from or obtained by the method as described in the second aspect, or an exhaust gas treatment system as described in the third aspect.

[0116] Implementation

[0117] Various embodiments are listed below. It should be understood that the embodiments listed below can be combined with all aspects of the scope of the present invention and other embodiments.

[0118] 1. A particle filter, comprising:

[0119] - 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 number of the channels are inlet channels open at the inlet end and closed at the outlet end, and a number of the channels are outlet channels closed at the inlet end and open at the outlet end; and

[0120] - an in-wall TWC coating in the inlet channel and the outlet channel, the in-wall TWC coating comprising a platinum group metal component, an alumina-based refractory metal oxide and an oxygen storage component, wherein the weight ratio of the alumina-based refractory metal oxide to the oxygen storage component of the in-wall TWC coating is in the range of 1:20 to 1:3, and

[0121] The TWC coating inside the wall does not contain any separate zirconium or barium substance.

[0122] 2. The particulate filter according to embodiment 1, wherein the weight ratio of the alumina-based refractory metal oxide to the oxygen storage component is from 1:15 to 1:4, more preferably from 1:10 to

[0123] 1:5, most preferably in the range of 1:10 to 1:7.

[0124] 3. A particulate filter according to embodiment 1 or 2, wherein the alumina-based refractory metal oxide is selected from alumina, lanthanum oxide-doped alumina, lanthanum oxide-doped zirconia alumina, ceria-doped alumina, zirconia-doped alumina, ceria-zirconia-doped alumina, or any combination thereof, more preferably alumina, lanthanum oxide-doped alumina, or a combination thereof.

[0125] 4. A particulate filter according to any one of the preceding embodiments, wherein the oxygen storage component is selected from cerium dioxide, or a composite oxide of cerium dioxide and one or more of lanthanum oxide, praseodymium oxide, neodymium oxide, europium oxide, samarium oxide, ytterbium oxide, yttrium oxide, zirconium oxide and hafnium oxide, preferably a composite oxide of cerium dioxide and one or more of lanthanum oxide, praseodymium oxide, neodymium oxide, yttrium oxide and zirconium oxide.

[0126] 5. A particulate filter according to any one of the preceding embodiments, wherein the wall TWC coating in the inlet channel extends from the inlet end of the channel along 50% to 100% of the axial length of the inlet channel, and the wall TWC coating in the outlet channel extends from the inlet end of the channel along 50% to 100% of the axial length of the inlet channel.

[0127] The TWC coating extends from the outlet end of the channel along 50% to 100% of the axial length of the outlet channel.

[0128] 6. A particulate filter according to embodiment 5, wherein the in-wall TWC coating in the inlet channel and the in-wall TWC coating in the outlet channel extend along 50% to 75%, more preferably 50% to 60%, and most preferably 50% to 55% of the axial length of the corresponding channel.

[0129] 7. The particulate filter according to any one of the preceding embodiments, wherein the in-wall TWC coating in the inlet channel and the in-wall TWC coating in the outlet channel have the same composition.

[0130] 8. The particulate filter according to any one of the preceding embodiments, wherein the platinum group metal component is a Pt component, a Pd component, a Rh component, or any combination thereof.

[0131] 9. The particulate filter according to any one of the preceding embodiments, wherein the platinum group metal component is a combination of an Rh component, a Pt component and optionally a Pd component.

[0132] 10. A method for producing a particle filter according to any one of the preceding embodiments

[0133] The method comprises the following steps:

[0134] - providing a slurry comprising mixing a platinum group metal component or a precursor thereof, an alumina-based refractory metal oxide and an oxygen storage component in a solvent, wherein the platinum group metal is not pre-fixed on the alumina-based refractory metal oxide and the oxygen storage component prior to said mixing, and

[0135] - applying the slurry into the inlet and outlet channels of the substrate,

[0136] To form a TWC coating inside the wall.

[0137] 11. The method according to embodiment 10, wherein the slurry comprises additives such as accelerators, binders, stabilizers, viscosity modifiers, pH modifiers, surfactants, or any combination thereof.

[0138] 12. The method according to embodiment 10 or 11, wherein the precursor of the platinum group metal component is selected from the group consisting of soluble salts, complexes, oxides and colloids of the platinum group metal.

[0139] 13. The method according to any one of embodiments 10 to 12, comprising drying and calcining after applying the slurry.

[0140] 14. The method of any one of embodiments 10 to 13, wherein the solvent is water.

[0141] 15. A method according to any one of embodiments 10 to 14, wherein the slurry is provided by mixing a Pt component or a precursor thereof and an oxygen storage component in a solvent, to which an alumina-based refractory metal oxide is added, and then the Rh component or a precursor thereof is added.

[0142] 16. The method according to any one of embodiments 10 to 14, wherein the slurry is provided by mixing the Rh component or a precursor thereof with an alumina-based refractory metal oxide in a solvent, an oxygen storage component is added to the solvent, and then the Pt component or a precursor thereof is added.

[0143] 17. An exhaust gas treatment system comprising a particle filter according to any one of embodiments 1 to 9, preferably a particle filter obtainable from or obtained from a method according to any one of embodiments 10 to 16, the particle filter being located downstream of a gasoline engine.

[0144] 18. A method for treating exhaust gases from a gasoline engine, the method comprising contacting the exhaust gases with a particle filter according to any one of embodiments 1 to 9, preferably a particle filter obtainable from or obtained from a method according to any one of embodiments 10 to 16, or an exhaust gas treatment system according to embodiment 17.

[0145] Example

[0146] Various aspects of the present invention are more fully illustrated by the following examples, which are set forth for the purpose of illustrating certain aspects of the present invention and should not be construed as limiting the present invention.

[0147] I. Preparation of Catalytic Gasoline Particulate Filter

[0148] Example 1 (E1, containing Ba / Zr, pre-fixed, alumina / OSC ratio of 0.37)

[0149] By applying the TWC washcoat slurry to a blank filter substrate ( The blank filter substrate has a size of 118.4 mm (D) × 127 mm (L) and a volume of 1.4 L (about 85.4 in). 3 ), a hole density of 300 holes per square inch (cpsi) and a wall thickness of 8 mils.

[0150] 23.93 g of a 16.39 wt% aqueous solution of hexahydroxyplatinic acid diethanolamine salt was mixed with 277 g of deionized water and impregnated in a planetary mixer (P-mixer) onto 693 g of La / Y-doped ceria-zirconia composite oxide (OSC, 40% ceria, 5% lanthanum oxide, 5% yttrium oxide, and the balance zirconium oxide) to form a wet Pt / OSC powder while achieving initial wetness. The wet Pt / OSC powder was mixed with 752 g of deionized water, 55 g of barium nitrate, and 39 g of a 21.6 wt% aqueous solution of zirconium nitrate to form a Pt / OSC slurry. The slurry was adjusted to pH 3.5 with nitric acid and ground to a particle size D 90 is 4.5μm.

[0151] 20.29 g of a 9.67 wt % aqueous rhodium nitrate solution was mixed with 179 g of deionized water and impregnated onto 256 g of gamma alumina powder in a planetary mixer (P-mixer) to form a wet Rh / alumina powder while achieving initial wetness. The wet Rh / alumina powder was mixed with 160 g of deionized water, 23 g of barium nitrate and 26 g of a 21.6 wt % aqueous zirconium nitrate solution to form a Rh / alumina slurry. The slurry was adjusted to pH 3.5 with nitric acid and ground to a particle size D 90 is 4.5μm.

[0152] The Pt / OSC slurry and the Rh / alumina slurry were combined into a final slurry and then coated from the inlet end of the filter substrate along 52% of the axial length of the filter using 50% of the target washcoat loading, and from the outlet end of the filter substrate using the remaining 50% of the target washcoat loading along up to about 52% of the axial length of the filter. The coated substrate was then dried at 150° C. for 1 h and then calcined at 550° C. for 1 h.

[0153] The obtained inner wall TWC coating has a thermal conductivity of 1.48 g / in 3 Washcoat loading and 15.0 g / ft 3 The total PGM loading was 100%, with a Pt / Rh ratio of 10 / 5.

[0154] Example 2 (E2, containing Ba / Zr, pre-fixed, alumina / OSC ratio of 0.30)

[0155] A particulate filter with an in-wall TWC coating was prepared from a blank filter substrate identical to the filter substrate of Example 1 by applying the TWC washcoat slurry into both the inlet and outlet channels of the blank filter.

[0156] 23.93 g of a 16.39 wt% aqueous solution of hexahydroxyplatinic acid diethanolamine salt was mixed with 292 g of deionized water and impregnated onto 730 g of La / Y doped ceria-zirconia composite oxide (OSC, 40% ceria, 5% lanthanum oxide, 5% yttrium oxide and the balance zirconium oxide) in a planetary mixer (P-mixer) to form a wet Pt / OSC powder while achieving initial wetness. The wet Pt / OSC powder was mixed with 792 g of deionized water, 55 g of barium nitrate and 39 g of a 21.6 wt% aqueous solution of zirconium nitrate to form a Pt / OSC slurry. The slurry was adjusted to pH 3.5 with nitric acid and ground to a particle size D 90 is 4.5μm.

[0157] 20.29 g of a 9.67 wt % aqueous rhodium nitrate solution was mixed with 153 g of deionized water and impregnated onto 219 g of gamma alumina powder in a planetary mixer (P-mixer) to form a wet Rh / alumina powder while achieving initial wetness. The wet Rh / alumina powder was mixed with 120 g of deionized water, 23 g of barium nitrate and 26 g of a 21.6 wt % aqueous zirconium nitrate solution to form a Rh / alumina slurry. The slurry was adjusted to pH 3.5 with nitric acid and ground to a particle size D 90 is 4.5μm.

[0158] The Pt / OSC slurry and the Rh / alumina slurry were combined into a final slurry and then coated from the inlet end of the filter substrate along 52% of the axial length of the filter using 50% of the target washcoat loading, and from the outlet end of the filter substrate using the remaining 50% of the target washcoat loading along up to about 52% of the axial length of the filter. The coated substrate was then dried at 150° C. for 1 h and then calcined at 550° C. for 1 h.

[0159] The obtained inner wall TWC coating has a thermal conductivity of 1.48 g / in 3 Washcoat loading and 15.0 g / ft 3 The total PGM loading was 100%, with a Pt / Rh ratio of 10 / 5.

[0160] Example 3 (E3, containing Ba / Zr, pre-fixed, alumina / OSC ratio of 0.20)

[0161] A particulate filter with an in-wall TWC coating was prepared from a blank filter substrate identical to the filter substrate of Example 1 by applying the TWC washcoat slurry into both the inlet and outlet channels of the blank filter.

[0162] 23.93 g of a 16.39 wt% aqueous solution of hexahydroxyplatinic acid diethanolamine salt was mixed with 316 g of deionized water and impregnated in a planetary mixer (P-mixer) onto 791 g of La / Y-doped ceria-zirconia composite oxide (OSC, 40% ceria, 5% lanthanum oxide, 5% yttrium oxide, and the balance zirconium oxide) to form a wet Pt / OSC powder while achieving initial wetness. The wet Pt / OSC powder was mixed with 858 g of deionized water, 55 g of barium nitrate, and 39 g of a 21.6 wt% aqueous solution of zirconium nitrate to form a Pt / OSC slurry. The slurry was adjusted to pH 3.5 with nitric acid and ground to a particle size D 90 is 4.5μm.

[0163] 20.29 g of a 9.67 wt % aqueous rhodium nitrate solution was mixed with 111 g of deionized water and impregnated onto 158 g of gamma alumina powder in a planetary mixer (P-mixer) to form a wet Rh / alumina powder while achieving initial wetness. The wet Rh / alumina powder was mixed with 99 g of deionized water, 23 g of barium nitrate and 26 g of a 21.6 wt % aqueous zirconium nitrate solution to form a Rh / alumina slurry. The slurry was adjusted to pH 3.5 with nitric acid and ground to a particle size D 90 is 4.5μm.

[0164] The Pt / OSC slurry and the Rh / alumina slurry were combined into a final slurry and then coated from the inlet end of the filter substrate along 52% of the axial length of the filter using 50% of the target washcoat loading, and from the outlet end of the filter substrate using the remaining 50% of the target washcoat loading along up to about 52% of the axial length of the filter. The coated substrate was then dried at 150° C. for 1 h and then calcined at 550° C. for 1 h.

[0165] The obtained inner wall TWC coating has a thermal conductivity of 1.48 g / in 3 Washcoat loading and 15.0 g / ft 3 The total PGM loading was 100%, with a Pt / Rh ratio of 10 / 5.

[0166] Example 4 (E4, containing Ba / Zr, pre-fixed, alumina / OSC ratio of 0.12)

[0167] A particulate filter with an in-wall TWC coating was prepared from a blank filter substrate identical to the filter substrate of Example 1 by applying the TWC washcoat slurry into both the inlet and outlet channels of the blank filter.

[0168] 23.93 g of a 16.39 wt% aqueous solution of hexahydroxyplatinic acid diethanolamine salt was mixed with 338 g of deionized water and impregnated in a planetary mixer (P-mixer) onto 846 g of La / Y-doped ceria-zirconia composite oxide (OSC, 40% ceria, 5% lanthanum oxide, 5% yttrium oxide and the balance zirconium oxide) to form a wet Pt / OSC powder while achieving initial wetness. The wet Pt / OSC powder was mixed with 912 g of deionized water, 55 g of barium nitrate and 39 g of a 21.6 wt% aqueous solution of zirconium nitrate to form a Pt / OSC slurry. The slurry was adjusted to pH 3.5 with nitric acid and ground to a particle size D 90 is 4.5μm.

[0169] 20.29 g of a 9.67 wt % aqueous rhodium nitrate solution was mixed with 72 g of deionized water and impregnated onto 103 g of gamma alumina powder in a planetary mixer (P-mixer) to form a wet Rh / alumina powder while achieving initial wetness. The wet Rh / alumina powder was mixed with 68 g of deionized water, 23 g of barium nitrate and 26 g of a 21.6 wt % aqueous zirconium nitrate solution to form a Rh / alumina slurry. The slurry was adjusted to pH 3.5 with nitric acid and ground to a particle size D 90 is 4.5μm.

[0170] The Pt / OSC slurry and the Rh / alumina slurry were combined into a final slurry and then coated from the inlet end of the filter substrate along 52% of the axial length of the filter using 50% of the target washcoat loading, and from the outlet end of the filter substrate using the remaining 50% of the target washcoat loading along up to about 52% of the axial length of the filter. The coated substrate was then dried at 150° C. for 1 h and then calcined at 550° C. for 1 h.

[0171] The obtained inner wall TWC coating has a thermal conductivity of 1.48 g / in 3 Washcoat loading and 15.0 g / ft 3 The total PGM loading was 100%, with a Pt / Rh ratio of 10 / 5.

[0172] Example 5 (E5, containing Ba / Zr, pre-fixed, alumina / OSC ratio of 0.12)

[0173] A particulate filter with an in-wall TWC coating was prepared from a blank filter substrate identical to the filter substrate of Example 1 by applying the TWC washcoat slurry into both the inlet and outlet channels of the blank filter.

[0174] 11.99 g of a 16.39 wt% aqueous solution of hexahydroxyplatinic acid diethanolamine salt was mixed with 338 g of deionized water and impregnated in a planetary mixer (P-mixer) onto 846 g of La / Y-doped ceria-zirconia composite oxide (OSC, 40% ceria, 5% lanthanum oxide, 5% yttrium oxide and the balance zirconium oxide) to form a wet Pt / OSC powder while achieving initial wetness. The wet Pt / OSC powder was mixed with 912 g of deionized water, 55 g of barium nitrate and 39 g of a 21.6 wt% aqueous solution of zirconium nitrate to form a Pt / OSC slurry. The slurry was adjusted to pH 3.5 with nitric acid and ground to a particle size D 90 is 4.5μm.

[0175] 20.33 g of a 9.67 wt % aqueous rhodium nitrate solution was mixed with 72 g of deionized water and impregnated onto 103 g of gamma alumina powder in a planetary mixer (P-mixer) to form a wet Rh / alumina powder while achieving initial wetness. The wet Rh / alumina powder was mixed with 68 g of deionized water, 23 g of barium nitrate and 26 g of a 21.6 wt % aqueous zirconium nitrate solution to form a Rh / alumina slurry. The slurry was adjusted to pH 3.5 with nitric acid and ground to a particle size D 90 is 4.5μm.

[0176] The Pt / OSC slurry and the Rh / alumina slurry were combined into a final slurry and then coated from the inlet end of the filter substrate along 52% of the axial length of the filter using 50% of the target washcoat loading, and from the outlet end of the filter substrate using the remaining 50% of the target washcoat loading along up to about 52% of the axial length of the filter. The coated substrate was then dried at 150° C. for 1 h and then calcined at 550° C. for 1 h.

[0177] The obtained inner wall TWC coating has a thermal conductivity of 1.48 g / in 3 Washcoat loading and 10.0 g / ft 3 The total PGM loading was 500 wt % with a Pt / Rh ratio of 5 / 5.

[0178] Example 6 (E6, containing Ba / Zr, pre-fixed, alumina / OSC ratio of 0.05)

[0179] A particulate filter with an in-wall TWC coating was prepared from a blank filter substrate identical to the filter substrate of Example 1 by applying the TWC washcoat slurry into both the inlet and outlet channels of the blank filter.

[0180] 11.99 g of a 16.39 wt% aqueous solution of hexahydroxyplatinic acid diethanolamine salt was mixed with 357 g of deionized water and impregnated in a planetary mixer (P-mixer) onto 892 g of La / Y-doped ceria-zirconia composite oxide (OSC, 40% ceria, 5% lanthanum oxide, 5% yttrium oxide and the balance zirconium oxide) to form a wet Pt / OSC powder while achieving initial wetness. The wet Pt / OSC powder was mixed with 875 g of deionized water, 55 g of barium nitrate and 39 g of a 21.6 wt% aqueous solution of zirconium nitrate to form a Pt / OSC slurry. The slurry was adjusted to pH 3.5 with nitric acid and ground to a particle size D 90 is 4.5μm.

[0181] 20.33 g of a 9.67 wt % aqueous rhodium nitrate solution was mixed with 32 g of deionized water and impregnated onto 45 g of gamma alumina powder in a planetary mixer (P-mixer) to form a wet Rh / alumina powder while achieving initial wetness. The wet Rh / alumina powder was mixed with 22 g of deionized water, 23 g of barium nitrate and 26 g of a 21.6 wt % aqueous zirconium nitrate solution to form a Rh / alumina slurry. The slurry was adjusted to pH 3.5 with nitric acid and ground to a particle size D 90 is 4.5μm.

[0182] The Pt / OSC slurry and the Rh / alumina slurry were combined into a final slurry and then coated from the inlet end of the filter substrate along 52% of the axial length of the filter using 50% of the target washcoat loading, and from the outlet end of the filter substrate using the remaining 50% of the target washcoat loading along up to about 52% of the axial length of the filter. The coated substrate was then dried at 150° C. for 1 h and then calcined at 550° C. for 1 h.

[0183] The obtained inner wall TWC coating has a thermal conductivity of 1.48 g / in 3 Washcoat loading and 10.0 g / ft 3 The total PGM loading was 500 wt % with a Pt / Rh ratio of 5 / 5.

[0184] Example 7 (E7, containing Ba / Zr, pre-fixed, without aluminum oxide)

[0185] A particulate filter with an in-wall TWC coating was prepared from a blank filter substrate identical to the filter substrate of Example 1 by applying the TWC washcoat slurry into both the inlet and outlet channels of the blank filter.

[0186] 11.99 g of a 16.39 wt% aqueous solution of hexahydroxyplatinic acid diethanolamine salt was mixed with 338 g of deionized water and impregnated in a planetary mixer (P-mixer) onto 846 g of La / Y-doped ceria-zirconia composite oxide (OSC, 40% ceria, 5% lanthanum oxide, 5% yttrium oxide and the balance zirconium oxide) to form a wet Pt / OSC powder while achieving initial wetness. The wet Pt / OSC powder was mixed with 912 g of deionized water, 55 g of barium nitrate and 39 g of a 21.6 wt% aqueous solution of zirconium nitrate to form a Pt / OSC slurry. The slurry was adjusted to pH 3.5 with nitric acid and ground to a particle size D 90 is 4.5μm.

[0187] 20.29 g of a 9.67 wt % aqueous rhodium nitrate solution was mixed with 41 g of deionized water and impregnated in a planetary mixer (P-mixer) onto 103 g of La / Y-doped ceria-zirconia composite oxide (OSC, 40% ceria, 5% lanthanum oxide, 5% yttrium oxide and the balance zirconium oxide) to form a wet Rh / OSC powder while achieving initial wetness. The wet Rh / OSC powder was mixed with 68 g of deionized water, 23 g of barium nitrate and 26 g of a 21.6 wt % aqueous zirconium nitrate solution to form a Rh / OSC slurry. The slurry was adjusted to pH 3.5 with nitric acid and ground to a particle size D 90 is 4.5μm.

[0188] The Pt / OSC slurry and the Rh / OSC slurry were combined into a final slurry and then coated from the inlet end of the filter substrate along 52% of the axial length of the filter using 50% of the target washcoat loading, and from the outlet end of the filter substrate using the remaining 50% of the target washcoat loading along up to about 52% of the axial length of the filter. The coated substrate was then dried at 150°C for 1 h and then calcined at 550°C for 1 h.

[0189] The obtained inner wall TWC coating has a thermal conductivity of 1.48 g / in 3 Washcoat loading and 10.0 g / ft 3 The total PGM loading was 500 wt % with a Pt / Rh ratio of 5 / 5.

[0190] Example 8 (E8, containing Zr, without Ba, pre-fixed, alumina / OSC ratio 0.12)

[0191] A particulate filter with an in-wall TWC coating was prepared from a blank filter substrate identical to the filter substrate of Example 1 by applying the TWC washcoat slurry into both the inlet and outlet channels of the blank filter.

[0192] 11.99 g of a 16.39 wt% aqueous solution of hexahydroxyplatinic acid diethanolamine salt was mixed with 338 g of deionized water and impregnated onto 846 g of La / Y doped ceria-zirconia composite oxide (OSC, 40% ceria, 5% lanthanum oxide, 5% yttrium oxide and the balance zirconium oxide) in a planetary mixer (P-mixer) to form a wet Pt / OSC powder while achieving initial wetness. The wet Pt / OSC powder was mixed with 912 g of deionized water, 39 g of a 21.6 wt% aqueous solution of zirconium nitrate to form a Pt / OSC slurry. The slurry was adjusted to pH 3.5 with nitric acid and ground to a particle size D 90 is 4.5μm.

[0193] 20.33 g of a 9.67 wt % aqueous rhodium nitrate solution was mixed with 72 g of deionized water and impregnated onto 103 g of gamma alumina powder in a planetary mixer (P-mixer) to form a wet Rh / alumina powder while achieving initial wetness. The wet Rh / alumina powder was mixed with 68 g of deionized water, 26 g of a 21.6 wt % aqueous zirconium nitrate solution to form a Rh / alumina slurry. The slurry was adjusted to pH 3.5 with nitric acid and ground to a particle size D 90 is 4.5μm.

[0194] The Pt / OSC slurry and the Rh / alumina slurry were combined into a final slurry and then coated from the inlet end of the filter substrate along 52% of the axial length of the filter using 50% of the target washcoat loading, and from the outlet end of the filter substrate using the remaining 50% of the target washcoat loading along up to about 52% of the axial length of the filter. The coated substrate was then dried at 150° C. for 1 h and then calcined at 550° C. for 1 h.

[0195] The obtained inner wall TWC coating has a thermal conductivity of 1.48 g / in 3 Washcoat loading and 10.0 g / ft 3 The total PGM loading was 500 wt % with a Pt / Rh ratio of 5 / 5.

[0196] Example 9 (E9, without Ba and Zr, pre-fixed, alumina / OSC ratio of 0.12)

[0197] A particulate filter with an in-wall TWC coating was prepared from a blank filter substrate identical to the filter substrate of Example 1 by applying the TWC washcoat slurry into both the inlet and outlet channels of the blank filter.

[0198] 11.99 g of a 16.39 wt% aqueous solution of hexahydroxyplatinic acid diethanolamine salt was mixed with 338 g of deionized water and impregnated in a planetary mixer (P-mixer) onto 846 g of La / Y-doped ceria-zirconia composite oxide (OSC, 40% ceria, 5% lanthanum oxide, 5% yttrium oxide, and the balance zirconium oxide) to form a wet Pt / OSC powder while achieving initial wetness. The wet Pt / OSC powder was mixed with 912 g of deionized water to form a Pt / OSC slurry. The slurry was adjusted to pH 3.5 with nitric acid and ground to a particle size D 90 is 4.5μm.

[0199] 20.33 g of a 9.67 wt % aqueous rhodium nitrate solution was mixed with 72 g of deionized water and impregnated onto 103 g of gamma alumina powder in a planetary mixer (P-mixer) to form a wet Rh / alumina powder while achieving initial wetness. The wet Rh / alumina powder was mixed with 68 g of deionized water to form a Rh / alumina slurry. The slurry was adjusted to pH 3.5 with nitric acid and ground to a particle size D 90 is 4.5μm.

[0200] The Pt / OSC slurry and the Rh / alumina slurry were combined into a final slurry and then coated from the inlet end of the filter substrate along 52% of the axial length of the filter using 50% of the target washcoat loading, and from the outlet end of the filter substrate using the remaining 50% of the target washcoat loading along up to about 52% of the axial length of the filter. The coated substrate was then dried at 150° C. for 1 h and then calcined at 550° C. for 1 h.

[0201] The obtained inner wall TWC coating has a thermal conductivity of 1.48 g / in 3 Washcoat loading and 10.0 g / ft 3 The total PGM loading was 500 wt % with a Pt / Rh ratio of 5 / 5.

[0202] Example 10 (E10, containing Ba / Zr, pre-fixed, alumina / OSC ratio of 0.12)

[0203] A particulate filter with an in-wall TWC coating was prepared from a blank filter substrate identical to the filter substrate of Example 1 by applying the TWC washcoat slurry into both the inlet and outlet channels of the blank filter.

[0204] 26.80 g of a 16.39 wt% aqueous solution of hexahydroxyplatinic acid diethanolamine salt was mixed with 338 g of deionized water and impregnated in a planetary mixer (P-mixer) onto 846 g of La / Y-doped ceria-zirconia composite oxide (OSC, 40% ceria, 5% lanthanum oxide, 5% yttrium oxide and the balance zirconium oxide) to form a wet Pt / OSC powder while achieving initial wetness. The wet Pt / OSC powder was mixed with 912 g of deionized water, 55 g of barium nitrate and 39 g of a 21.6 wt% aqueous solution of zirconium nitrate to form a Pt / OSC slurry. The slurry was adjusted to pH 3.5 with nitric acid and ground to a particle size D 90 is 4.5μm.

[0205] 15.10 g of a 9.67 wt % aqueous rhodium nitrate solution was mixed with 72 g of deionized water and impregnated onto 103 g of gamma alumina powder in a planetary mixer (P-mixer) to form a wet Rh / alumina powder while achieving initial wetness. The wet Rh / alumina powder was mixed with 68 g of deionized water, 23 g of barium nitrate and 26 g of a 21.6 wt % aqueous zirconium nitrate solution to form a Rh / alumina slurry. The slurry was adjusted to pH 3.5 with nitric acid and ground to a particle size D 90 is 4.5μm.

[0206] The Pt / OSC slurry and the Rh / alumina slurry were combined into a final slurry and then coated from the inlet end of the filter substrate along 52% of the axial length of the filter using 50% of the target washcoat loading, and from the outlet end of the filter substrate using the remaining 50% of the target washcoat loading along up to about 52% of the axial length of the filter. The coated substrate was then dried at 150° C. for 1 h and then calcined at 550° C. for 1 h.

[0207] The obtained inner wall TWC coating has a thermal conductivity of 1.98 g / in 3 Washcoat loading and 20.0 g / ft 3 The total PGM loading was 15:5, with a Pt / Rh ratio of 15:5.

[0208] Example 11 (E11, containing Ba / Zr, one-pot process, alumina / OSC ratio of 0.12)

[0209] A particulate filter with an in-wall TWC coating was prepared from a blank filter substrate identical to the filter substrate of Example 1 by applying the TWC washcoat slurry into both the inlet and outlet channels of the blank filter.

[0210] 26.80 g of a 16.39 wt% aqueous solution of hexahydroxyplatinic acid diethanolamine salt was mixed with 1360 g of deionized water, and then 846 g of La / Y-doped ceria-zirconia composite oxide (OSC, 40% ceria, 5% lanthanum oxide, 5% yttrium oxide and the balance of zirconium oxide), 78 g of barium nitrate, 65 g of a 21.6 wt% aqueous solution of zirconium nitrate, 103 g of gamma alumina powder, and 15.10 g of a 9.67 wt% aqueous solution of rhodium nitrate were added to form a slurry. The slurry was adjusted to pH 3.5 with nitric acid and ground to a particle size D 90 is 4.5μm.

[0211] The slurry was then coated from the inlet end of the filter substrate along 52% of the axial length of the filter using 50% of the target washcoat loading, and the remaining 50% of the target washcoat loading was coated from the outlet end of the filter substrate along up to about 52% of the axial length of the filter. The coated substrate was then dried at 150°C for 1 hour and then calcined at 550°C for 1 hour.

[0212] The obtained inner wall TWC coating has a thermal conductivity of 1.98 g / in 3 Washcoat loading and 20.0 g / ft 3 The total PGM loading was 15:5, with a Pt / Rh ratio of 15:5.

[0213] Example 12 (E12, containing Ba / Zr, pre-fixed, alumina / OSC ratio of 0.37)

[0214] A particulate filter with an in-wall TWC coating was prepared by applying a TWC washcoat slurry to both the inlet and outlet channels of a blank filter substrate. The dimensions of the blank filter substrate were 118.4 mm (D) (127 mm (L) and a volume of 1.4 L (approximately 85.4 in 3 ), a hole density of 300 holes per square inch (cpsi) and a wall thickness of 8 mils.

[0215] 47.60 g of a 16.39 wt% aqueous solution of hexahydroxyplatinic acid diethanolamine salt was mixed with 277 g of deionized water and impregnated in a planetary mixer (P-mixer) onto 693 g of La / Y-doped ceria-zirconia composite oxide (OSC, 40% ceria, 5% lanthanum oxide, 5% yttrium oxide and the balance zirconium oxide) to form a wet Pt / OSC powder while achieving initial wetness. The wet Pt / OSC powder was mixed with 752 g of deionized water, 55 g of barium nitrate and 39 g of a 21.6 wt% aqueous solution of zirconium nitrate to form a Pt / OSC slurry. The slurry was adjusted to pH 3.5 with nitric acid and ground to a particle size D 90 is 4.5μm.

[0216] 40.30 g of a 9.67 wt % aqueous rhodium nitrate solution was mixed with 180 g of deionized water and impregnated onto 256 g of gamma alumina powder in a planetary mixer (P-mixer) to form a wet Rh / alumina powder while achieving initial wetness. The wet Rh / alumina powder was mixed with 160 g of deionized water, 23 g of barium nitrate and 26 g of a 21.6 wt % aqueous zirconium nitrate solution to form a Rh / alumina slurry. The slurry was adjusted to pH 3.5 with nitric acid and ground to a particle size D 90 is 4.5μm.

[0217] The Pt / OSC slurry and the Rh / alumina slurry were combined into a final slurry and then coated from the inlet end of the filter substrate along 52% of the axial length of the filter using 50% of the target washcoat loading, and from the outlet end of the filter substrate using the remaining 50% of the target washcoat loading along up to about 52% of the axial length of the filter. The coated substrate was then dried at 150° C. for 1 h and then calcined at 550° C. for 1 h.

[0218] The obtained inner wall TWC coating has a thermal conductivity of 1.48 g / in 3 Washcoat loading and 30.0 g / ft 3 The total PGM loading was 20:1 with a Pt / Rh ratio of 20:10.

[0219] Example 13 (E13, without Ba and Zr, one-pot process, alumina / OSC ratio of 0.12)

[0220] A particulate filter with an in-wall TWC coating was prepared from a blank filter substrate identical to the filter substrate of Example 1 by applying the TWC washcoat slurry into both the inlet and outlet channels of the blank filter.

[0221] 47.60 g of a 16.39 wt% aqueous solution of hexahydroxyplatinic acid diethanolamine salt was mixed with 1534 g of deionized water, and then 896 g of La / Y-doped ceria-zirconia composite oxide (OSC, 40% ceria, 5% lanthanum oxide, 5% yttrium oxide and the balance of zirconium oxide) 111 g of γ-alumina powder and 40.30 g of a 9.67 wt% aqueous solution of rhodium nitrate were added to form a slurry. The slurry was adjusted to pH 3.5 with nitric acid and ground to a particle size D 90 is 4.5μm.

[0222] The slurry was then coated from the inlet end of the filter substrate along 52% of the axial length of the filter using 50% of the target washcoat loading, and the remaining 50% of the target washcoat loading was coated from the outlet end of the filter substrate along up to about 52% of the axial length of the filter. The coated substrate was then dried at 150°C for 1 hour and then calcined at 550°C for 1 hour.

[0223] The obtained inner wall TWC coating has a thermal conductivity of 1.48 g / in 3 Washcoat loading and 30.0 g / ft 3 The total PGM loading was 20:1 with a Pt / Rh ratio of 20:10.

[0224] II. Performance Evaluation

[0225] II.1 Oxygen storage capacity and catalytic activity

[0226] The oxygen storage capacity and gas emissions of particulate filters E1 to E13 were studied. Before evaluation, the samples were exotherm aged for 100 hours at an inlet temperature of 875°C on a GM 8.1LV8 engine. The same samples as E12 and E13 were also tested in a fresh, unaged state. The fixed oxygen storage capacity (SOSC) value of each sample was measured in a closed couple position on an Audi 2.0L turbocharged engine, with an inlet temperature of 580°C and a flow rate of 50kg / h. Under the WLTC scheme, the gas emissions of each sample were measured in a closed couple position on a Daimler 2.0L engine, and THC, CO and NOx emissions were measured downstream of each sample. Lower emission values ​​indicate that the catalytic activity of the filter is higher. The results of SOSC values ​​and gas emissions are shown in Tables 1 to 4.

[0227] Table 1

[0228]

[0229] From the comparison between E1 and E2 to E4, it can be seen that the catalyzed particulate filters with inner-wall TWC coatings having alumina / OSC ratios of 0.12, 0.20 and 0.30 exhibit significantly higher SOSC values ​​and lower gas emissions (THC, CO and NOx) compared to the catalyzed particulate filter with an inner-wall TWC coating having an alumina / OSC ratio of 0.37.

[0230] It can also be seen from the comparison between E5 or E6 and E7 that the catalyzed particulate filters with inner-wall TWC coatings with alumina / OSC ratios of 0.12 and 0.05 exhibit significantly higher SOSC values ​​and lower gas emissions (THC, CO and NOx) than the catalyzed particulate filter with an inner-wall TWC coating with alumina / OSC ratios of 0, which is unexpected because the catalyzed particulate filters with inner-wall TWC coatings with alumina / OSC ratios of 0.12 and 0.05 even exhibit higher SOSC values ​​than their counterparts containing a single oxygen storage component.

[0231] Table 2

[0232]

[0233] From the comparison between E5 and E8 and the comparison between E8 and E9, it can be seen that the absence of either barium oxide or zirconium oxide alone in the TWC coating inside the wall of the catalytic particulate filter can lead to improvements in oxygen storage capacity and catalytic activity. In addition, it can be seen that the absence of both barium oxide and zirconium oxide alone in the TWC coating inside the wall can lead to the highest SOSC value and the highest catalytic activity.

[0234] Table 3

[0235]

[0236] Catalyzed particulate filter E10 was obtained from a slurry prepared via a conventional method including pre-fixing PGM onto a support, whereas catalyzed particulate filter E11 was obtained from a slurry prepared via a one-pot method. Surprisingly, catalyzed particulate filter E11 showed higher SOSC values ​​and higher catalytic activity than catalyzed particulate filter E10.

[0237] Table 4

[0238]

[0239] Table 4 (continued)

[0240]

[0241] As can be seen from the comparison between E12 and E13, in both the fresh and aged states, the catalyzed particulate filter with a reduced alumina / OSC ratio made from a slurry from a one-pot process in the absence of separate barium and zirconium species shows significantly improved oxygen storage capacity and catalytic activity compared to the catalyzed particulate filter with a conventional alumina / OSC ratio made from a slurry from a pre-fixation process in the presence of separate barium and zirconium species.

[0242] II.2 Increased back pressure contributed by the TWC coating inside the wall

[0243] The back pressure (BP) of the particle filters E12 and E13 was investigated, for example, by using a SuperFlow SF-1020 Flowbench at 600 m 3 The back pressure of the blank filter substrate before coating was also measured under the same conditions. The back pressure increase (ΔP) contributed by the TWC coating inside the wall was calculated according to the following equation:

[0244] ΔP = BP (coated) - BP (blank)

[0245] The results are shown in Table 5.

[0246] Table 5

[0247]

[0248] Compared to the conventional catalyzed particulate filter (E12), the catalyzed particulate filter (E13) according to the present invention exhibits a much lower ΔP contributed by the in-wall TWC coating.

[0249] Although the present 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 present invention. It will be apparent to those skilled in the art that various modifications and variations may be made to the methods and apparatus of the present invention without departing from the spirit and scope of the present invention. Therefore, the present invention is intended to include modifications and variations within the scope of the appended claims and their equivalents.

Claims

1. A particle 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 number of the channels are inlet channels open at the inlet end and closed at the outlet end, and a number of the channels are outlet channels closed at the inlet end and open at the outlet end; and - an in-wall TWC coating in the inlet channel and the outlet channel, the in-wall TWC coating comprising a platinum group metal component, an alumina-based refractory metal oxide and an oxygen storage component, wherein the weight ratio of the alumina-based refractory metal oxide to the oxygen storage component of the in-wall TWC coating is in the range of 1:20 to 1:3, and The in-wall TWC coating does not contain any separate zirconium species and barium species.

2. The particulate filter according to claim 1, wherein the weight ratio of the alumina-based refractory metal oxide to the oxygen storage component is in the range of 1:15 to 1:4, more preferably 1:10 to 1:5, most preferably 1:10 to 1:

7.

3. The particulate filter according to claim 1 or 2, wherein the alumina-based refractory metal oxide is selected from alumina, lanthanum oxide-doped alumina, lanthanum oxide-doped zirconia alumina, ceria-doped alumina, zirconia-doped alumina, ceria-zirconia-doped alumina or any combination thereof, more preferably alumina, lanthanum oxide-doped alumina or a combination thereof.

4. The particulate filter according to any one of the preceding claims, wherein the oxygen storage component is selected from cerium dioxide, or a composite oxide of cerium dioxide and one or more of lanthanum oxide, praseodymium oxide, neodymium oxide, europium oxide, samarium oxide, ytterbium oxide, yttrium oxide, zirconium oxide and hafnium oxide, preferably a composite oxide of cerium dioxide and one or more of lanthanum oxide, praseodymium oxide, neodymium oxide, yttrium oxide and zirconium oxide.

5. A particulate filter according to any one of the preceding claims, wherein the wall TWC coating in the inlet channel extends from the inlet end of the channel along 50% to 100% of the axial length of the inlet channel, and the wall TWC coating in the outlet channel extends from the inlet end of the channel along 50% to 100% of the axial length of the inlet channel. The TWC coating extends from the outlet end of the channel along 50% to 100% of the axial length of the outlet channel.

6. The particle filter according to claim 5, wherein the wall of the inlet channel The TWC coating and the in-wall TWC coating in the outlet channels extend along 50% to 75%, more preferably 50% to 60%, most preferably 50% to 55% of the axial length of the respective channels.

7. The particle filter according to any one of the preceding claims, wherein the inner-wall TWC coating in the inlet channel and the inner-wall TWC coating in the outlet channel have the same composition.

8. The particulate filter according to any one of the preceding claims, wherein the platinum group metal component is a Pt component, a Pd component, a Rh component or any combination thereof.

9. The particulate filter according to any one of the preceding claims, wherein the platinum group metal component is a combination of an Rh component, a Pt component and optionally a Pd component.

10. A method for producing a particle filter according to any one of the preceding claims, the method comprising the steps of: - providing a slurry comprising mixing a platinum group metal component or a precursor thereof, an alumina-based refractory metal oxide and an oxygen storage component in a solvent, wherein the platinum group metal is not pre-fixed on the alumina-based refractory metal oxide and the oxygen storage component prior to said mixing, and - applying the slurry into the inlet and outlet channels of the substrate, To form a TWC coating inside the wall.

11. The method of claim 10, wherein the slurry comprises additives such as accelerators, binders, stabilizers, viscosity modifiers, pH modifiers, surfactants, or any combination thereof.

12. The method according to claim 10 or 11, wherein the precursor of the platinum group metal component is selected from the group consisting of soluble salts, complexes, oxides and colloids of the platinum group metal.

13. A method according to any one of claims 10 to 12, comprising drying and calcining after applying the slurry.

14. The method according to any one of claims 10 to 13, wherein the solvent is water.

15. The method according to any one of claims 10 to 14, wherein the slurry is provided by mixing a Pt component or a precursor thereof and an oxygen storage component in a solvent, to which an alumina-based refractory metal oxide is added, and then a Rh component or a precursor thereof is added.

16. The method according to any one of claims 10 to 14, wherein the slurry is provided by mixing a Rh component or a precursor thereof with an alumina-based refractory metal oxide in a solvent, to which an oxygen storage component is added, and then a Pt component or a precursor thereof is added.

17. An exhaust gas treatment system comprising a particle filter according to any one of claims 1 to 9, preferably a particle filter obtainable or obtainable from a method according to any one of claims 10 to 16, the particle filter being located downstream of a gasoline engine.

18. A method for treating exhaust gases from a gasoline engine, the method comprising contacting the exhaust gases with a particle filter according to any one of claims 1 to 9, preferably a particle filter obtainable or obtainable from a method according to any one of claims 10 to 16, or an exhaust gas treatment system according to claim 17.

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