Method of forming an inorganic oxide coating on a monolith article

Abstract

A method of forming an inorganic oxide coating on a monolithic article is disclosed. The coated monolithic article is suitable for treating exhaust gas. The method includes spraying a dry particulate aerosol of inorganic particles and a silicone resin to form the coating. The invention also provides an uncalcined porous monolithic article for forming a monolithic article for treating exhaust gas. The uncalcined monolithic article includes a dry particulate composition including inorganic particles and a silicone resin.

Description

Technical Field

[0001] This invention relates to a method for forming an inorganic oxide coating on a monolithic article. In particular, the coated monolithic article is suitable for treating waste gas. More specifically, the method includes spraying inorganic particles and an organosilicon resin as a dry particulate aerosol to form the coating. The invention also relates to an uncalcined porous monolithic article for forming monolithic articles for treating waste gas. In particular, the uncalcined monolithic article comprises a dry particulate composition containing inorganic particles and an organosilicon resin. Background Technology

[0002] There are concerns about particulate matter (PM) emissions (commonly known as soot) from internal combustion engines, particularly diesel and gasoline engines used in automotive applications. The main concern is related to potential health effects, especially the presence of very small particles in the nanometer range.

[0003] Diesel particulate filters (DPFs) and gasoline particulate filters (GPFs) are manufactured using a variety of materials, including sintered metals, ceramics, or metal fibers. The most common type in actual mass production is the wall-flow type, made of porous ceramic materials, which are manufactured as a monolithic array of numerous small channels extending along the length of the body. Alternating channels are blocked at one end, thus forcing exhaust gas through the porous ceramic channel walls, which prevent most particles from passing through, allowing only filtered gas to enter the environment. Commercially produced ceramic wall-flow filters include those made of cordierite, various forms of silicon carbide, and aluminum titanate. The actual shape and size of the filters used in vehicles, as well as characteristics such as channel wall thickness and porosity, depend on the application of interest. The average pore size in the filter channel walls of ceramic wall-flow filters through which gas passes is typically in the range of 5 μm to 50 μm, and is usually around 20 μm. In stark contrast, most diesel particulate matter from modern passenger car high-speed diesel engines is much, much smaller, ranging from 10 nm to 200 nm.

[0004] Some particulate matter (PM) may remain within the pore structure of the filter wall, and in some applications this can gradually accumulate until the pores are bridged by a network of PM, which then allows for the easy formation of a particulate cake on the inner wall of the filter channels. The particulate cake is an excellent filter medium, and its presence provides very high filtration efficiency. In some applications, soot is continuously burned on the filter during deposition, which prevents the accumulation of particulate cake on the filter.

[0005] For some filters, such as light-duty diesel particulate filters, it is necessary to periodically remove captured PM from the filter to prevent the buildup of excessive back pressure, which is detrimental to engine performance and can lead to poor fuel economy. Therefore, in diesel applications, the retained PM is removed from the filter by burning it in air during a process in which the amount of available air and excess fuel required to reach the high temperature needed to ignite the retained PM is carefully controlled. At the end of this process, commonly known as regeneration, removing the last remaining particles from the filter can result in a significant decrease in filtration efficiency and a burst of release of many small particles into the environment. Therefore, the filter may have low filtration efficiency during initial use and subsequently after each regeneration event and also during the latter part of each regeneration process.

[0006] Therefore, it is desirable to improve and / or maintain filtration efficiency at any time—for example, during the early lifespan of the filter when it is first used, and / or during and immediately after regeneration, and / or when the filter is loaded with soot.

[0007] WO 2011 / 151711 (the entire contents of which are incorporated herein by reference) describes a method for manufacturing a filter for filtering particulate matter from exhaust gases emitted from a lean-burn internal combustion engine. The filter includes a porous substrate having an inlet surface and an outlet surface, wherein the inlet surface is separated from the outlet surface by a porous structure containing pores of a first average pore size. The inlet surface includes a bridging network comprising interconnected refractory material particles on the pores of the porous structure. The method includes the step of contacting the inlet surface of the filter substrate with an aerosol comprising a refractory material in the form of dry powder.

[0008] WO 2021 / 028692 (the entire contents of which are incorporated herein by reference) describes a vehicle exhaust filter comprising a porous substrate having an inlet face and an outlet face, the porous substrate including an inlet channel extending from the inlet face and an outlet channel extending from the outlet face; the inlet channel and the outlet channel are separated by a plurality of filter walls having a porous structure; the vehicle exhaust filter is loaded with refractory powder having a tapped density of less than 0.10 g / cm³ prior to loading. 3 The vehicle exhaust filter has a mass loading of less than 10 g / L of refractory powder; and wherein more than 40% of the refractory powder is located within the porous structure of multiple filter walls, and less than 60% of the refractory powder is coated on the outer surface of the multiple filter walls. WO 2021 / 028692 also describes suitable methods and apparatus for spraying dry refractory powder, such as dry particulate aerosol, onto channels of a porous substrate, preferably wherein more than 50% of the refractory powder, optionally up to 100% of the refractory powder, may be positioned together with the porous structure of the multiple filter walls.

[0009] WO 2020 / 047708 discloses articles comprising porous bodies such as porous ceramic honeycombs, and methods for manufacturing such articles and porous bodies, the porous body comprising a material such as a filter material, for example, a porous inorganic layer disposed on at least a portion of the porous body. The method includes contacting an inorganic material in a suspension with a gaseous carrier liquid, the suspension being water-based or organic-based, such as an alcohol such as ethanol or methanol.

[0010] The inventors have discovered that porous filter substrates treated with refractory powder materials as described in WO 2021 / 028692 exhibit poor water resistance and adhesion. For example, pyrolytic alumina (e.g., The porous filter substrate treated with Alu130 failed to provide the water resistance required for use under certain engine conditions, particularly during continuous engine cold starts. As mentioned above, for example, for heavy-duty diesel (HDD) catalytic dust filter (CSF) applications, the filter must be able to withstand several dust cleaning cycles.

[0011] The inventors developed this invention to mitigate and / or overcome problems observed in the prior art. This invention provides an improved method for producing more efficient coated monolithic articles that advantageously exhibit higher water resistance and improved filtration efficiency. Summary of the Invention

[0012] According to a first aspect of the present invention, a method for forming an inorganic oxide coating on a monolithic article for treating waste gas is provided, the method comprising:

[0013] A porous monolithic article is provided, comprising multiple channels for the passage of exhaust gas, each channel having a gas contact surface;

[0014] Inorganic particles and organosilicon resin are sprayed as dry particulate aerosols onto the gas contact surface to form a coating; and

[0015] The coating is calcined to provide coated monolithic articles.

[0016] In another aspect, an uncalcined porous monolithic article is provided for forming a monolithic article for treating waste gas, the monolithic article being obtainable by a method comprising the following steps:

[0017] A porous monolithic article is provided, comprising multiple channels for the passage of exhaust gas, each channel having a gas contact surface;

[0018] Inorganic particles and organosilicon resin are sprayed as dry particulate aerosols onto the gas contact surface to form a coating.

[0019] In another aspect, a coated monolithic article is provided for treating exhaust gases that can be obtained by the methods described herein with respect to the first aspect. The coated monolithic article has enhanced water resistance compared to known coated monolithic articles, and as described herein, the article is preferably a catalytic article and / or a wall-flow filter. This article is particularly suitable for treating exhaust gases, especially vehicle exhaust gases. The inventors have discovered that the highly cross-linked silica present in the coated monolithic article is very effective in binding inorganic particles to the gas contact surface of the channels of the porous monolithic article.

[0020] In another aspect of the invention, a vehicle exhaust system comprising a coated monolithic article is provided. Attached Figure Description

[0021] Figure 1 The filtration efficiency data of control sample C-1, fresh sample C-1, and sample C-1 after water immersion treatment were compared.

[0022] Figure 2 The filtration efficiency data of control sample C-1, fresh sample C-2, and sample C-2 after water immersion were compared.

[0023] Figure 3 The filtration efficiency data of fresh sample C-5 and worn sample C-5 were compared. Detailed Implementation

[0024] According to a first aspect of the present invention, a method for forming an inorganic oxide coating on a monolithic article for treating waste gas is provided, the method comprising:

[0025] A porous monolithic article is provided, comprising multiple channels for the passage of exhaust gas, each channel having a gas contact surface;

[0026] Inorganic particles and organosilicon resin are sprayed as dry particulate aerosols onto the gas contact surface to form a coating; and

[0027] The coating is calcined to provide coated monolithic articles.

[0028] This disclosure will now be described further. In the following paragraphs, different aspects / implementations of this disclosure are defined in more detail. Unless expressly stated to the contrary, each aspect / implementation so defined may be combined with any other aspect / implementation or multiple aspects / implementations. Specifically, any feature indicated as preferred or advantageous may be combined with any other feature indicated as preferred or advantageous, or one or more other features.

[0029] The method of the present invention forms an inorganic oxide coating on a monolithic article, thereby forming a coated monolithic article. The monolithic article with the inorganic oxide coating is then suitable for treating exhaust gases. The exhaust gases may preferably be lean-burn exhaust gases from a vehicle engine, and the exhaust gases are treated by passing them through channels in the monolithic article, thereby bringing the exhaust gases into contact with the gas contact surfaces of multiple channels.

[0030] The method includes providing a porous monolithic article comprising a plurality of channels for the passage of exhaust gas, each channel having a gas contact surface. Porous monolithic articles are well known in the art. Porous monolithic articles are sometimes referred to as substrates, preferably honeycomb substrates, and preferably ceramic honeycomb substrates. Such substrates include a plurality of channels suitable for the passage of exhaust gas. The channels are parallel and extend from an inlet end (or a first end) to an outlet end (or a second end), i.e., the channels extend axially through the article. Typically, the channels have a square cross-section, but any known monolithic design can be used.

[0031] Porous monolithic articles / substrates can be formed, for example, from sintered metals, ceramics, or metal fibers. For instance, the article can be formed from cordierite, various forms of silicon carbide, or aluminum titanate.

[0032] In some embodiments, the integral material article is an integral material filter. Particularly preferred is that the integral material filter is a wall-flow filter (also referred to as a wall-flow integral material article). Wall-flow filters are well known, and typically, adjacent channels are alternately blocked at each end of the integral material article, such that during use, exhaust gas passes through the inlet channel (i.e., the channel that opens at the inlet end of the integral material article to receive exhaust gas) and is forced through the channel wall into the adjacent outlet channel (i.e., the channel that opens at the outlet end of the integral material article).

[0033] The channel walls have a fine pore distribution that provides the required porosity for the integral material. The average size of the pores in the channel walls (e.g., filter walls) is typically in the range of 5 μm to 50 μm. Each channel has a gas contact surface. That is, each channel has a surface suitable for contact with exhaust gases during use, for example. This surface may be provided by the channel wall surface and / or the pores contained therein.

[0034] In another particularly preferred embodiment, the porous monolithic article is a catalyst article (i.e., a catalytic article). Catalytic porous monolithic articles are well known and exhibit properties such as oxidation, NO... xCatalytic function with trapping or selective catalytic reduction activity. Porous monolithic articles may include one or more support coatings, preferably catalytic support coatings. The support coating is a composition that coats and permeates the porous structure of the article. The article including the one or more support coatings is then preferably calcined before spraying inorganic particles and organosilicon resin onto the channels as described herein. Therefore, the catalyst article may be selected from, for example, three-way catalysts (TWC), NO... x Adsorbents, oxidation catalysts, selective reduction catalysts (SCR), hydrocarbon traps, and dilute NO x Catalysts. Catalyst products may contain one or more platinum group metals, particularly those selected from the group consisting of platinum, palladium, and rhodium.

[0035] In a particularly preferred embodiment, the porous monolithic article is a catalyst wall-flow filter. Therefore, this article can be, for example, a catalytic dust filter (CSF), a selective catalytic reduction filter (SCRF), or a dilute NO filter. x A trap filter (LNTF), a gasoline particulate filter (GPF), an ammonia leak catalyst filter (ASCF), or a combination of two or more of them (e.g., a filter including a selective catalytic reduction (SCR) catalyst and an ammonia leak catalyst (ASC).

[0036] The shape and dimensions of a filter (e.g., characteristics such as channel wall thickness and porosity) can vary depending on the intended application of the filter. A filter can be configured for use with an internal combustion engine to filter exhaust gases emitted by that engine. The internal combustion engine can be a gasoline spark-ignition engine. However, when configured for use with an internal combustion engine in the form of a diesel or gasoline engine, the filter has a specific application.

[0037] Wall-flow filters can be asymmetric wall-flow filters. An asymmetric wall-flow filter design is known, for example, from WO2005 / 030365, which discloses a honeycomb filter comprising an array of interconnected porous walls defining an array of first and second channels. The first channel is defined on its sides by the second channel and has a larger hydraulic diameter than the second channel. The first channel has a square cross-section, wherein the corners of the first channel have a shape such that the thickness of the porous wall adjacent to the corner of the first channel is comparable to the thickness of the porous wall adjacent to the edges of the first and second channels. In use, the first channel with the larger hydraulic diameter is oriented to the upstream side. SAE Technical Paper Series 2007-01-0656 explains: “For ACT designs, there is a pressure drop loss in the clean state due to the contraction and expansion of the gas at the filter channel inlet and outlet [for catalytically asymmetric channel technology (ACT) wall-flow filters]. However, when operating in a vehicle, the time the filter is in a completely clean (fully regenerated) state is very short.” WO2005 / 030365 also explains the advantages of asymmetric filter designs, including the increased effective surface area available for collecting soot and ash particles in the inlet section of the cellular filter, thereby increasing the total storage capacity of the cellular filter. The general knowledge textbook "Catalytic Air Pollution Control—Commercial Technology," 3rd edition, by Ronald M. Heck et al., John Wiley Corporation, Hoboken, NJ (2009), pp. 338-340, explains: "This type of [asymmetric filter] channel design achieves a combination of higher ash storage capacity and lower ash loading back pressure due to a larger hydraulic diameter and higher open volume at the inlet. The ACT design also helps maintain the mechanical and thermal durability of the filter."

[0038] The method further includes spraying inorganic particles and silicone resin as dry particulate aerosols onto the gas contact surface to form a coating. Therefore, the method includes spraying dry powder (i.e., dry particles) suspended in a gas (i.e., as an aerosol) onto the gas contact surface of a multi-channel integral article. Spraying dry powder onto an integral article is known in the art. Suitable methods and apparatus are described, for example, in WO 2011 / 151711 and WO 2021 / 028692.

[0039] The inventors have surprisingly discovered that by including a silicone resin in the dry powder used to form the dry particulate aerosol, the resulting article exhibits significantly improved water resistance, and that the silicone resin facilitates the adhesion of inorganic particles to the surface of the channel wall. It has been found that the improved retention of inorganic particles increases the filtration efficiency of the article, making the bulk filter article a particularly preferred embodiment for utilizing the benefits derived from including a silicone resin.

[0040] A key advantage of this invention is that monolithic articles (such as filters containing catalyst in the filter walls) can be processed after the catalyst is carried on the filter, and the inorganic coating does not interfere with the catalyst in and / or on the filter walls. Furthermore, the inventors have discovered that the silicone resin described herein does not require potentially harmful high-temperature treatments to the catalyst, and allows the inorganic particles to be more effectively retained and adhered to the article channels.

[0041] Organosilicon resins are known to be branched cage-like oligomeric siloxanes and polysiloxanes. The branching in organosilicon resins is due to the presence of so-called "T" and / or "Q" units in the resin, referring to RSiO3 and SiO4 units respectively (R being alkyl or aryl), where additional silicon units are bonded to oxygen atoms. "M" units (i.e., R3SiO units) are terminal units, where oxygen atoms provide the connection to the resin backbone. Similarly, "D" units (i.e., R2SiO2 units) provide a linear connection across two oxygen atoms. A well-known unbranched and linear polysiloxane is polydimethylsiloxane (PDMS; i.e., (Me2SiO)). n ).

[0042] As will be understood, the requirement to spray inorganic particles and silicone resins as dry particulate aerosols necessitates that the silicone resin be a solid particulate. Therefore, silicone resin may be referred to herein as silicone resin particles. Preferably, the silicone resin is a solid at room temperature (e.g., about 25°C). Therefore, the silicone resin preferably has a melting point greater than 25°C, preferably greater than 30°C, more preferably greater than 35°C. Preferably, the silicone resin has a melting point less than 100°C, preferably less than 95°C, less than 90°C, less than 85°C, or less than 80°C. Unbranched polysiloxanes such as PDMS typically have lower melting points than branched silicone resins. For example, PDMS has a melting point of about -40°C. WO2011 / 151711 discloses treating powders bonded at appropriate locations with polydimethylsiloxane, which hydrolyzes at sufficiently high temperatures to form silica.

[0043] Similarly, the inventors have found that it is preferable for the silicone resin to have a glass transition temperature (Tg) greater than 30°C, preferably greater than 35°C, and / or less than 100°C, preferably less than 80°C. Without wishing to be bound by theory, the inventors believe that silicone resins with such melting points and / or glass transition temperatures are particularly suitable for powder coating processes, i.e., for the effective dispersion of microparticles together with inorganic particles on a monolithic article, but with a melting point and / or glass transition temperature low enough to allow for low-temperature calcination, thereby effectively and efficiently adhering inorganic particles to the gas contact surface of the channel wall.

[0044] Preferably, the inorganic particles are selected from the group consisting of zeolites, refractory oxides, and mixtures thereof. Examples of suitable zeolites include silicate zeolites, aluminosilicate zeolites, metal-substituted aluminosilicate zeolites, AlPO, MeAlPO, SAPO, MeAPSO, etc. In some embodiments, the first and second zeolites are independently selected from aluminosilicate zeolites, borosilicate zeolites, gallium silicate zeolites, SAPO zeolites, AlPO zeolites, MeAPSO zeolites, and MeAPO zeolites. In some embodiments, the zeolite has a framework type selected from the following: ABW, ACO, AEI, AEL, AEN, AET, AFG, AFI, AFN, AFO, AFR, AFS, AFT, AFX, AFY, AHT, ANA, APC, APD, AST, ASV, ATN, ATO, ATS, ATT, ATV, AVL, AWO, AWW, BCT, BEA, BEC, BIK, BOG, BPH, BRE, CAN, CAS, SCO, C FI, SGF, CGS, CHA, CHI, CLO, CON, CZP, DAC, DDR, DFO, DFT, DOH, DON, EAB, EDI, EEI, EMT, EON, EPI, ERI, ESV, ETR, EUO, FAU, FER, FRA, GIS, GIU, GME, GON, GOO, HEU, IFR, IFY, IHW, IRN, ISV, ITE, ITH, ITW, IWR, IWW, JBW, KFI, LAU , LEV, LIO, LIT, LOS, LOV, LTA, LTL, LTN, MAR, MAZ, MEI, MEL, MEP, MER, MFI, MFS, MON, MOR, MOZ, MSO, MTF, MTN, M TT, MTW, MWF, MWW, NAB, NAT, NES, NON, NPO, NPT, NSI, OBW, OFF, OSI, OSO, OWE, PAR, PAU, PHI, PON, RHO, RON, RRO, RSN, RTE, RTH, RUT, RWR, RWY, SAO, SAS, SAT, SAV, SBE, SBS, SBT, SFE, SFF, SFG, SFH, SFN, SFO, SFW, SGT, SOD, SOS , SSY, STF, STI, STT, TER, THO, TON, TSC, UEI, UFI, UOZ, USI, UTL, VET, WI, VNI, VSV, WIE, WEN, YUG, ZON, or their combination.In some embodiments, the zeolite has a framework type selected from the following: AEI, AFT, AFV, AFX, AVL, BEA, CHA, DDR, EAB, EEI, ERI, FAU, FER, IFY, IRN, KFI, LEV, LTA, LTN, MER, MOR, MWF, MFI, NPT, PAU, RHO, RIE, RTH, SAS, SAT, SAV, SFW, TSC, and UFI.

[0045] In another preferred embodiment, the inorganic particles are refractory oxide particles, which may be based on oxides selected from the group consisting of: alumina, silica, zirconium oxide, cerium dioxide, chromium oxide, magnesium oxide, calcium oxide, titanium dioxide, and any mixtures of two or more of these. Preferably, the refractory oxide particles include calcium aluminate, pyrolytic alumina, pyrolytic silica, pyrolytic titanium dioxide, pyrolytic zirconium oxide, pyrolytic cerium dioxide, alumina aerogel, silica aerogel, titanium dioxide aerogel, zirconium oxide aerogel, cerium dioxide aerogel, or mixtures thereof. The one or more refractory powders (refractory oxide particles) can be produced by a pyrochemical process, such as flame pyrolysis.

[0046] An example of inorganic particles is silicic acid.

[0047] Preferably, the inorganic particles and / or organosilicon resin particles have a d-size of greater than 0.2 μm, preferably greater than 0.5 μm, and / or less than 50 μm, preferably less than 25 μm, preferably less than 20 μm, preferably less than 15 μm, and preferably less than 10 μm by volume. 50 .

[0048] Preferably, the dry particulate aerosol has a tapped density of less than 1.5 g / cm³. 3 A dry microparticle composition is formed. This dry microparticle composition may be referred to as dry microparticle powder. The dry microparticle composition preferably consists of inorganic particles and / or organosilicon resin. In some preferred embodiments, the inorganic particles have a content of less than 0.1 g / cm³. 3 (Typically for gas-phase refractory oxides) tap density. In other preferred embodiments, the inorganic particles have a tap density greater than 0.1 g / cm³. 3 Preferably, it is greater than 0.2 g / cm³. 3 The tap density. For example, zeolite particles such as Cu-substituted zeolites may preferably have a tap density of about 0.25 g / cm³. 3 The tap density. In other preferred embodiments, inorganic particles, such as refractory oxide particles, may have a tap density of less than 1.4 g / cm³. 3 Preferably less than 1.3 g / cm³ 3 Preferably less than 1.2 g / cm³ 3The tap density. By way of example only, calcium aluminate can have a tap density of approximately 1 g / cm³. 3 The tap density is [value missing]. Therefore, the inorganic particles can preferably have a tap density of 0.1 g / cm³. 3 Up to 1.4 g / cm 3 Preferably 0.2 g / cm 3 Up to 1.2 g / cm 3 The tap density. Organosilicon resin particles can have a tap density of 0.3 g / cm³. 3 Up to 0.9 g / cm 3 Preferably 0.5 g / cm 3 Up to 0.7 g / cm 3 The tap density. A dry particulate composition consisting of a mixture of inorganic particles and silicone resin may preferably have the same tap density as described individually for either the inorganic particles or the silicone resin. In some preferred embodiments, the tap density of the dry particulate composition is 0.5 g / cm³. 3 Up to 1.4 g / cm 3 Preferably 0.7 g / cm 3 Up to 1.2 g / cm 3 .

[0049] In a preferred embodiment, the spraying step includes a first spraying step in which the inorganic particles are sprayed as a first dry particulate aerosol onto the gas contact surface to form an inorganic particle layer, and then in a second spraying step, the silicone resin is sprayed as a second dry particulate aerosol onto the inorganic particle layer to form the coating. Thus, the inorganic particle layer is sprayed onto the channels of the monolithic article, and then the silicone resin is separately sprayed onto the channels coated with the inorganic particles.

[0050] Even more preferably, the mixture of the inorganic particles and the silicone resin is sprayed as a dry particulate aerosol onto the gas contact surface to form the coating. Thus, a tight mixture of inorganic particles and silicone resin is coated onto the gas contact surface of the channel, and the adhesion of the inorganic particles to the channel wall is enhanced during the calcination of the silicone resin.

[0051] When a mixture of inorganic particles and silicone resin is sprayed as a dry particulate aerosol onto a gas-contact surface to form a coating (preferably, wherein the dry particulate composition consists of inorganic particles and silicone resin), the weight ratio of inorganic particles to silicone resin in the mixture is preferably greater than 0.5 (in other words, greater than 0.5:1), preferably greater than 0.7, preferably greater than 0.9, and / or less than 4, preferably less than 3, preferably less than 2.5. For example, this ratio may preferably be about 1 or about 2. Preferably, the ratio is 0.5 to 4, preferably 0.7 to 3, preferably 0.9 to 2.5, preferably 1 to 2.

[0052] Preferably, the silicone resin has a molecular weight greater than 1,000, preferably greater than 2,000, preferably greater than 5,000, preferably greater than 10,000, and / or less than 500,000, preferably less than 200,000.

[0053] As used in this article, molecular weight refers to weight-average molecular weight (M). W The molecular weight can be measured using any conventional apparatus in the art. In some embodiments, particularly those described herein in which the silicone resin contains hydroxyl functional groups, the molecular weight may be relatively low because the hydrogen bonds provided by the hydroxyl functional groups provide the silicone resin with a sufficiently high melting point and / or glass transition temperature. Thus, in some embodiments, the molecular weight of the silicone resin may be from 1,000 to 10,000, preferably from 1,000 to 5,000, preferably from 1,200 to 3,500, such as from 1,500 to 2,000. Silicone resins with a molecular weight below 1,000 are less preferred because these silicone resins are typically liquids and are not suitable for dry spraying, or do not have as much branching as larger molecules, which are considered to enhance the bonding of inorganic particles to monolithic articles.

[0054] However, the molecular weight of the silicone resin is preferably from 15,000 to 150,000, preferably from 20,000 to 120,000, and preferably from 60,000 to 100,000. Some preferred resins have a molecular weight of 8,000 to 15,000, some resins have a molecular weight of 20,000 to 60,000, and others have a molecular weight of 80,000 to 120,000.

[0055] Particularly preferred is that the organosilicon resin has the formula [R] x SiX y O z ] n Where R is an alkyl or aryl group, X is a functional group bonded to silicon, and z is greater than 1 and less than 2. As will be understood, n is large in order to provide the desired oligomers or polymers of silicone resins, particularly resins that are solid at room temperature. Although dependent on the molecular weight of the R and X groups, when n is greater than 10, M > 1,000 can be obtained. W When n is greater than 100, an M greater than 10,000 can be obtained. W Furthermore, when n is greater than 1,000, an M greater than 100,000 can be obtained. W Therefore, n can preferably be greater than 10, greater than 100, or greater than 1,000.

[0056] As will be understood, R is an alkyl or aryl group bonded to silicon, and X is a non-hydrocarbon functional group bonded to silicon. Likewise, since silicon is a tetravalent atom, it is understood that x+y+2z=4. z is less than 2, because when z=2 and x and y=0, silica is obtained (i.e., silicon dioxide; (SiO2) n ). Similarly, z is greater than 1, because when z=1 and x+y=2, substituted polysiloxanes consisting of "D" units are obtained, for example (RXSiO) n ), resulting in linear resins (e.g., –O–(SiRX)–O–(SiRX)–O–). One example is polydimethylsiloxane. Therefore, O refers to oxygen that bridges two silicon atoms in the polymer backbone of the silicone resin.

[0057] Preferably, 0<x+y<2, preferably 0<x+y≤1.5, preferably 0<x+y≤1. Preferably, x, y and / or x+y is greater than 0.1, preferably greater than 0.2. In a preferred embodiment, x+y is 1, resulting in a silicone resin generally known as polysilsesquioxane. Preferably, y is less than 1 and / or y is less than x. Even more preferably, 2y≤x, preferably 5y≤x, preferably 10y≤x. In one embodiment, y is 0. For example, y is 0, wherein the polysilsesquioxane is a polyalkylsilsesquioxane, for example polymethylsilsesquioxane (MeSiO 3 / 2 ) n .

[0058] Generally, when present, X is one or more of H, a hydroxyl group (OH), Cl and C1–C6 alkoxy, preferably one or more of OH and C1–C6 alkoxy, preferably wherein the C1–C6 alkoxy is selected from methoxy (OCH3) and ethoxy (OCH2CH3). In a particularly preferred embodiment, X is one or both of OH and ethoxy. However, X is a functional group, which can also be a reactive functional group such as an amine group (NH2, NR2), an epoxy group, an acrylate group and a vinyl group, but these functional groups are less preferred because the presence of hydroxyl or alkoxy groups is believed to provide more efficient crosslinking during calcination. As mentioned above, any oxygen present in terminal functional groups does not contribute to "O" in the above formula z ", and the "O z " refers to silicon that bridges oxygen atoms.

[0059] The inventors have discovered that the silicone resins described herein provide coated monolithic articles with the advantageous benefit of enhanced water resistance. Silicone resins have been found to be particularly advantageous in bonding inorganic particles to monolithic articles. Without wishing to be bound by theory, the inventors believe that the branched structure and physical properties of silicone resins allow the resin to first melt in the calcination step as described herein, and then begin to cure after bonding (tightly bonding or depositing) with inorganic particles on the gas contact surface of the channel. As the resin cures, additional –Si–O–Si–O–Si– bridges / bonds are formed, further increasing its branched structure. Additionally, the inventors believe that this bonding can also be formed, for example, by forming –Si–O–Al– bonds together with the gas contact surface (i.e., the monolithic article itself) and the inorganic particles, further bonding the particles to appropriate locations within the article. As the temperature continues to rise during calcination, the R and X groups are oxidized, leaving behind a silica (SiO2) framework. Therefore, inorganic particles containing silicon and / or aluminum may be preferred, such as zeolites, calcium aluminate, alumina, and / or silica.

[0060] Preferably, the silicone resin has a crosslinking degree of greater than 55%, more preferably greater than 60%, more preferably greater than 65%, and / or less than 85%, preferably less than 80%.

[0061] As discussed in this paper, given the tetravalent nature of silicon, such as formula [R] x SiX y O z ] n The silicon atoms in the described silicone resin can be located in one of four coordination environments: SiO(R / X)3, SiO2(R / X)2, SiO3(R / X), or SiO4, referred to in the art as “M”, “D”, “T”, and “Q”, respectively. Therefore, the above formula can be described by aMbDcTdQ, where a+b+c+d=1, and the degree of crosslinking is defined by [(a+2b+3c+4d) / 4]*100. The relative ratio of the number of silicon atoms in each coordination environment can be determined using standard spectroscopic techniques (e.g., multinuclear NMR spectroscopy, especially...). 29 The degree of crosslinking is determined by Si NMR spectroscopy. Alternatively, for commercially available silicone resins, the degree of crosslinking can be provided in the technical data sheet.

[0062] In other words, silica (SiO2) is entirely formed from “Q”SiO4 units, where each silicon atom is bonded to four linked oxygen atoms. Therefore, with d=1, this results in silica having 100% crosslinking. On the other hand, by way of example, PDMS is entirely formed from “D”Si(Me)2O2. Therefore, with b=1, this results in polydimethylsiloxane having 50% crosslinking. Therefore, silicone resins preferably have a crosslinking degree between these two extremes and include mixtures of such units. Thus, silicone resins may preferably consist of MDT units, MTQ units, DTQ units, or DT units.

[0063] Preferably, R is one or more of C1-C6 alkyl or phenyl groups. Due to the oligomerizing or polymerizing nature of silicone resins, the number of monomer units is usually large. There are many cases where there are two groups, R and X, such that a silicone resin described as being composed of a single monomer unit can contain multiple different groups. As stated above regarding the functional group X, X can preferably be both OH and ethoxy. Similarly, R can include more than one C1-C6 alkyl and / or phenyl group. Therefore, when R is described by more than one group (such as R' and R''), the formula of the silicone resin can be [R' ... x’ R” x” SiX y O z ] n , where x'+x”=x. This also applies to functional group X.

[0064] Preferably, R is one or more of a straight-chain or branched alkyl group and a phenyl group, one or more of a straight-chain alkyl group and a phenyl group, and more preferably one or more of a methyl group and a phenyl group. In some preferred embodiments, R is simultaneously methyl and phenyl, and the ratio of phenyl to methyl is less than 2, preferably less than 1.5, preferably less than 1, and preferably less than 0.5. In some embodiments, R is phenyl. More preferably, R is methyl (i.e., the ratio is 0).

[0065] For the R and X groups, smaller organic groups such as methyl, methoxy, and ethoxy are particularly preferred because this increases the SiO2 content of the starting silicone resin, thereby reducing weight loss during calcination. Additionally, it reduces smoke and loss of volatiles (such as H2O, CO2, and other volatile organic compounds) during calcination.

[0066] Therefore, preferably, the silica content of the silicone resin is greater than 50% by weight, preferably greater than 60% by weight, preferably greater than 70% by weight, and preferably greater than 80% by weight. Silica content, also referred to as ash content, is the weight of the product remaining after complete oxidation (in this case, the product is silica), based on the weight of the starting silicone resin. For example, oxidation can be performed at approximately 1000°C. Alternatively, the silica content can be obtained from the technical data sheet of a suitable commercially available silicone resin. Alternatively, the silica content can be calculated based on the complete oxidation of silicon to silica and the resin's chemical formula. By way of example only, based on the weight of a silicone resin with a formula weight of 66.1 and a silicon atomic weight of 28.1, polymethylsilsesquioxane (MeSiO2)... 3 / 2 ) n It contains approximately 42.7% silicon by weight. Silica has a molecular weight of 60.1, which is approximately 2.1 times the molecular weight of silicon. Therefore, the silica content of polymethylsilsesquioxane is 2.1 * 42.7 = 89.7% by weight (i.e., based on the weight of the silicone resin).

[0067] A particularly preferred silicone resin for use in the method of the present invention is a highly cross-linked ethoxylated poly(dimethylsiloxane) having a silica content of about 82% by weight and a melting point of 35°C to 55°C.

[0068] The method also includes calcining the coating to provide a coated monolithic article. Specifically, the method includes calcining a porous monolithic article having inorganic particles and silicone resin sprayed onto a gas contact surface of multiple channels.

[0069] Preferably, the calcination step includes heating to a temperature of at least 200°C, preferably at least 300°C, more preferably at least 400°C, and / or at most 600°C, preferably at most 550°C, more preferably at most 530°C. Therefore, calcination preferably includes heating to a temperature of 200°C to 600°C, preferably 300°C to 550°C, preferably 400°C to 530°C, more preferably 400°C to 500°C, and even more preferably 400°C to 450°C.

[0070] Such temperatures have been found to be optimal for forming an effective binder that provides favorable water resistance to the coated monolithic article. These temperatures are particularly advantageous when the porous monolithic article is a catalytic article, such as a catalytic wall-flow filter, because they allow the silicone resin to be calcined into cross-linked silica without negatively impacting catalytic efficiency (i.e., without degrading the catalytic article). It is believed that linear siloxanes such as PDMS not only fail to provide the necessary branching for effective binding of inorganic particles and adhesion to the article, but also require temperatures exceeding 550°C or even 600°C for complete degradation into SiO2. Ideally, the calcination temperature should be kept as low as possible to minimize the possibility of affecting the catalytic activity of any catalyst present in the monolithic article.

[0071] In another aspect of the invention, an uncalcined porous monolithic article is provided for forming a monolithic article for treating waste gas, the uncalcined porous monolithic article comprising a plurality of channels and containing a dry particulate composition comprising inorganic particles and an organosilicon resin located within the channels and / or pores of the uncalcined porous monolithic article.

[0072] Therefore, uncalcined porous monolithic articles are suitable for forming monolithic articles that can be used for waste gas treatment. Preferably, the uncalcined porous monolithic article is used to form a monolithic article, preferably wherein the monolithic article will be used to treat waste gas. As described herein with respect to a first aspect, the uncalcined porous monolithic article includes a plurality of channels and comprises a dry particulate composition containing inorganic particles and organosilicon resin. The dry particulate composition is located within the channels and / or pores of the uncalcined porous monolithic article, that is, the composition coats the gas contact surfaces of the channels.

[0073] Uncalcined porous monolithic articles comprising dry particulate compositions can be formed by calcination, preferably by heating to the temperature described herein, thereby decomposing the silicone resin of the dry particulate composition into silicon dioxide.

[0074] Preferably, the mass loading of the dry particulate composition is less than 50 g / L, more preferably less than 30 g / L. Preferably, the mass loading of the inorganic particles is at least 5 g / L and / or less than 25 g / L. Preferably, the mass loading of the silicone resin is at least 5 g / L and / or less than 25 g / L. In a preferred embodiment, the mass loading of the inorganic particles is from 5 g / L to 15 g / L and / or the mass loading of the silicone resin is from 5 g / L to 15 g / L. By way of example, when the weight ratio of inorganic particles to silicone resin is 1:1, the loading of the inorganic particles can be 10 g / L, and the loading of the silicone resin can be 10 g / L, resulting in a total loading of 20 g / L for the dry particulate composition. By way of example, when the ratio is 2:1, the loading of the inorganic particles can be 10 g / L, and the loading of the silicone resin can be 5 g / L, resulting in a total loading of 15 g / L.

[0075] In another aspect, an uncalcined porous monolithic article is provided for forming a monolithic article for treating waste gas, the monolithic article being obtainable by a method comprising the following steps:

[0076] A porous monolithic article is provided, comprising multiple channels for the passage of exhaust gas, each channel having a gas contact surface;

[0077] Inorganic particles and organosilicon resin are sprayed as dry particulate aerosols onto the gas contact surface to form a coating.

[0078] In another aspect, a coated monolithic article is provided for treating exhaust gases obtainable by methods as described herein with respect to the first aspect. The coated monolithic article has enhanced water resistance compared to known coated monolithic articles, and as described herein, the article is preferably a catalytic article and / or a wall-flow filter. This article is particularly suitable for treating exhaust gases, especially vehicle exhaust gases. The inventors have discovered that the highly cross-linked silica present in the coated monolithic article is very effective in binding inorganic particles to the gas contact surface of the channels of the porous monolithic article.

[0079] In another aspect of the invention, a vehicle exhaust system comprising a coated monolithic article is provided.

[0080] Example A

[0081] Comparison sample A-1

[0082] GPF filters with a 50 g / L carrier coating were prepared from a 300 / 8, 1.3L cordierite substrate according to the procedure of Example 1 of US20200306692A1.

[0083] Comparison sample A-2

[0084] GPF filters were prepared in the same manner as control sample A-1.

[0085] Then, using the method and apparatus described in WO 2021 / 028692, 0.5 g / L pyrolytic alumina powder (d) was loaded into the prepared GPF filter. 50 =6μm, d 90 =12μm). The diameter of the flow duct is the same as the inlet face of the filter. A downstream regeneration blower is used to pump 550m... 3 The primary airflow of / h is drawn through the filter. The airflow is located below the filter. A P30 pressure transmitter was used to monitor the back pressure. Refractory powder was dispersed into the primary gas stream using a STAR Professional gravity feed nozzle (1.4mm part number STA2591100C). The 15 STAR Professional gravity feed nozzle was installed 100mm from the filter inlet. The back pressure was used to determine the point at which to stop spraying the refractory powder. After loading, the filter was calcined at 500°C for 1 hour.

[0086] Sample A-1

[0087] Sample A-1 was prepared in the same manner as control sample A-2, except that the latter was loaded with chabazite powder at a weight ratio of 2:1 (d 50 =2.4μm, d 90 =4.1μm) and highly cross-linked ethoxylated poly(dimethylsiloxane) powder (silica content of 82% by weight, melting point of 35°C to 55°C, d 50 =34μm, d 90 A mixture of particles with a diameter of 115 μm. The powder loading before calcination was 8 g / L.

[0088] Sample A-2

[0089] Following the procedure of Example 1 in US20200306692A1, a GPF filter with a 100 g / L carrier coating was prepared from a 300 / 8, 1.3L type cordierite substrate.

[0090] Following the loading procedure of comparative sample A-2, calcium aluminate powder (d) was loaded with a weight ratio of 1:1. 50 =53μm, d 90 =118μm) and highly cross-linked ethoxylated poly(dimethylsiloxane) powder (silica content 82% by weight, melting point 35°C to 55°C, d 50 =34μm, d 90 Sample A-2 was prepared using a mixture of powders with a particle size of 115 μm. The powder loading before calcination was 13.8 g / L.

[0091] Sample A-3

[0092] Sample A-3 was prepared in the same manner as control sample A-2, except that the latter was loaded with β-zeolite powder at a weight ratio of 1:1 (d 50 =6.4μm, d 90 =41μm) and highly cross-linked ethoxylated poly(dimethylsiloxane) powder (silica content 82% by weight, melting point 35°C to 55°C, d 50 =34μm, d 90A mixture of particles with a diameter of 115 μm. The powder loading before calcination was 20.7 g / L.

[0093] Filtering test

[0094] The filtration efficiency of samples (fresh and subjected to a series of cold start / idle tests) was tested on an engine bench during the RDE cycle, where the filter samples were subjected to 50 repeated cold start / idle cycles, during which water accumulated on the filters. The test results are listed in Table 1. The filtration efficiencies in Table 1 are the particulate matter removed over the entire driving cycle.

[0095] Table 1

[0096]

[0097] The results showed that, compared with the comparison sample A-2, the filtration efficiency of samples A-1, A-2 and A-3 decreased more from fresh to 50x cold start.

[0098] Example B

[0099] Comparison sample B-1

[0100] Following the procedure of Example 1 in US 8,789,356, SCRF filters with a 116 g / L carrier coating were prepared from an NGK MSC-18 300 / 12, 3L type silicon carbide (SiC) substrate. The carrier coating contained copper-loaded AEI zeolite, zirconium acetate, and alumina binder from Valiant (zeolite to alumina weight ratio = 90:10, zirconium = 40 g / ft). 3 The inlet coating length is approximately 20% of the substrate length; the outlet coating length is approximately 80% of the substrate length. The coated filter is dried at 110°C and calcined at 500°C for 1 hour.

[0101] Comparison sample B-2

[0102] SCRF filters were prepared in the same manner as control sample B-1. Then, using the method and apparatus of WO2021 / 028692, the prepared SCRF filters were loaded with pyrolytic alumina powder (d... 50 =6μm, d 90 =12μm). The diameter of the flow duct is the same as the inlet face of the filter. A downstream regeneration blower is used to pump 300m... 3 The primary airflow of / h is drawn through the filter. The airflow is located below the filter. A P30 pressure transmitter was used to monitor the back pressure. Powder was dispersed into the primary gas stream using a STAR Professional gravity feed nozzle (1.4mm part number STA2591100C). A 15-inch STAR Professional gravity feed nozzle was installed 100mm from the filter inlet. The point at which to stop spraying the refractory powder was determined using the back pressure parameters. The powder loading before calcination was 4 g / L. After loading, the filter was calcined at 500°C for 1 hour.

[0103] Sample B-1

[0104] Sample B-1 was prepared in the same manner as control sample B-2, except that the latter was loaded with spray-dried Cu chabazite (3.3 wt% Cu, d) at a weight ratio of 1:1. 90 =10μm-12μm) and highly cross-linked ethoxylated poly(dimethylsiloxane) powder (silica content of 82% by weight, melting point of 35°C to 55°C, d 50 =34μm, d 90 A mixture of particles with a diameter of 115 μm. The powder loading before calcination was 15 g / L.

[0105] Sample B-2

[0106] Sample B-2 was prepared in the same manner as control sample B-2. 15 g / L of spray-dried Cu chabazite (3.3 wt% Cu, d) was loaded into the sample at a weight ratio of 1:1. 90 =10μm-12μm) and highly cross-linked ethoxylated poly(dimethylsiloxane) powder (silica content of 82% by weight, melting point of 35°C to 55°C, d 50 =34μm, d 90 A mixture of 115 μm and other particles was placed in an oven at 110 °C for 15 minutes, then cooled to room temperature. Then, 5 g / L of chabazite (d) at a weight ratio of 1:1 was loaded into the sample. 90 =4.9μm) and a mixture of the same silicone resin powder. The total powder loading before calcination was 20 g / L.

[0107] Filtration efficiency

[0108] Use available from Cambustion Ltd., Cambridge, UK. The diesel particulate filter testing system tests filter samples under the following test conditions:

[0109] a) Stable flow rate—250 kg / h, 50°C, 5 minutes

[0110] b) Heating up – 250 kg / h mass flow rate, 240°C, 5 minutes

[0111] c) Weighing—Remove the filter from the test bench and weigh.

[0112] d) Heating—Filter returned to test bench; 250 kg / h mass flow rate, 240°C, 5 minutes

[0113] e) Loading stage—250 kg / h mass flow rate, 240℃, loading rate: 2 g / h until 2 g / L dust is reached.

[0114] f) Weighing — Remove the filter from the test bench and weigh.

[0115] The fuel used during the test was: Carcal RF-06-08B5.

[0116] During testing, the particle counter continuously samples downstream of the filter. Before and after testing a batch of filters, an "upstream" test is run immediately on the test bench to allow the particle counter to sample the raw dust generated from the test bench. The upstream test lasts 20 minutes and uses the same conditions as the loading phase described above. The filtration efficiency is obtained by comparing the average of the two upstream tests (before and after filter testing) with data from the loading phase of the filter test.

[0117] Fresh and water-immersion treated filter samples. In the water immersion treatment, the filters were submerged in water for 30 seconds, followed by drying at 110°C for 0.5 hours.

[0118] The filtration efficiency data collected 50 seconds after the start of the test are summarized in Table 2. The results show that samples B-1 and B-2, prepared by loading a mixture of zeolite powder and silicone resin, exhibit significantly improved water resistance compared to control sample 2.

[0119] Table 2

[0120]

[0121] Example C

[0122] Comparison sample C-1

[0123] CSF filters were prepared from a 300 / 6, 2.44L type silicon carbide filter substrate. The substrate was washed with a CSF catalyst composition with an alumina support, the catalyst composition having a PGM loading of 3 g / ft. 3 The Pt:Pd weight ratio is 2:1, and the carrier coating loading is 0.2 g / in. 3 .

[0124] Sample C-1

[0125] The CSF filter was prepared in the same manner as the control sample C-1.

[0126] Apply a 1:1 weight ratio of alumina (d) to the CSF filter using the method and apparatus described in WO 2021 / 028692. 50 =30μm, density =200g / L) and highly cross-linked ethoxylated poly(dimethylsiloxane) powder (silica content 82% by weight, melting point 35℃ to 55℃, d 50 =34μm, d 90 A mixture of powders with a diameter of 115 μm was applied. The diameter of the flow conduit was the same as the inlet face of the filter. The mixed powder was applied under continuous vacuum, generating an airflow of approximately 13 m / s. The powder was then placed below the filter. A P30 pressure transmitter was used to monitor the back pressure. Powder was dispersed into the primary gas stream using a STAR Professional gravity feed nozzle (1.4mm part number STA2591100C). A 15-inch STAR Professional gravity feed nozzle was installed 100mm from the filter inlet. The point at which to stop spraying the refractory powder was determined using the back pressure. 20 g / L of powder was loaded into the filter. The prepared filter was then calcined in air at 500°C for 1 hour.

[0127] Sample C-2

[0128] Sample C-2 was prepared in the same manner as sample C-1, except that boehmite (d) was applied to the filter at a weight ratio of 1:1. 50 =30μm, density =500g / L) and highly cross-linked ethoxylated poly(dimethylsiloxane) powder (silica content 82% by weight, melting point 35℃ to 55℃, d 50 =34μm, d 90 A mixture of powders (particles with a diameter of 115 μm) was used. 20 g / L of powder was loaded into a filter. The resulting filter was then calcined in air at 500 °C for 1 h.

[0129] Sample C-3

[0130] Sample C-3 was prepared in the same manner as control sample C-1.

[0131] Sample C-4

[0132] Sample C-4 was prepared in the same manner as control sample C-2.

[0133] Sample C-5

[0134] Sample C-5 was prepared in the same manner as sample C-1, except that a 1:1 mixture of silica (80 mesh) and highly cross-linked ethoxylated poly(dimethylsiloxane) powder (silica content 82% by weight, melting point 35°C to 55°C) was applied to the filter. 50 =34μm, d 90 A mixture of powders (particles with a diameter of 115 μm) was used. 20 g / L of powder was loaded into a filter. The resulting filter was then calcined in air at 500 °C for 1 h.

[0135] back pressure

[0136] Completely immerse samples C-1 and C-2 in a container of approximately 6 L of deionized water for about 10 seconds, then remove them from the water, shake the portion to remove excess water, and dry it in an oven at 115 °C for about 45 minutes.

[0137] At 600m 3 Cold flow back pressure tests were performed on samples C-1 and C-2 before and after water immersion treatment at a flow rate of / h. The test results are shown in Table 3.

[0138] Table 3

[0139]

[0140] Table 3 shows that water immersion only caused slight changes in the back pressure of samples C1 and C-2.

[0141] Filtration efficiency

[0142] The filtration test is performed using a commercially available Cambustion diesel particulate generator (DPG) test bench with an upstream PN baseline followed by downstream CSF measurements during the test (as described in Example B), thereby enabling the calculation of the filtration efficiency for each example.

[0143] Figure 1 The filtration efficiency data of control sample C-1, fresh sample C-1, and sample C-1 after water immersion treatment were compared.

[0144] Figure 2 The filtration efficiency data of control sample C-1, fresh sample C-2, and sample C-2 after water immersion were compared.

[0145] Figure 1 and Figure 2 The results show that a significantly higher filtration efficiency was achieved by adding refractory oxide powder to the CSF filter. Only a slight decrease in filtration efficiency was observed after samples C-1 and C-2 were immersed in water.

[0146] Gas wear test

[0147] Gas abrasion tests were performed on samples C-3, C-4, and C-5, which moved across the entire filter surface at a speed of 6.7 mm / s in a zigzag pattern, using a high-pressure air nozzle operating at a flow rate of 425 L / min, at a distance of 0.5 inches from the filter surface. Abrasion treatment was also performed from both the inlet and outlet faces of the filter. The samples were weighed before and after abrasion treatment, after drying in an oven at 115°C for 30 minutes.

[0148] At 600m 3 The flow rate was measured at / h during cold flow back pressure tests of samples C-3 and C-4 before and after water immersion treatment. The test results are shown in Table 4.

[0149] Table 4

[0150]

[0151] Figure 3 The filtration efficiency data of fresh sample C-5 and abrasion-treated sample C-5 were compared. After abrasion treatment, only a slight decrease in filtration efficiency was observed in sample C-5.

[0152] In this specification, the term "dry powder" refers to a particulate composition that is not suspended or dissolved in a liquid. This does not necessarily mean the complete absence of all water molecules. The dry powder is preferably free-flowing.

[0153] In this specification, the term "tap density" refers to the tap density of a powder measured by 1250 taps according to Method 1 of Section 2.9.35 of the European Pharmacopoeia 7.0.

[0154] In this specification, the term "g / L" (grams per liter) refers to the mass of the dry powder divided by the volume of the filter.

[0155] In this specification, when referring to the amount of powder, the terms "load" and "mass load" refer to the mass of powder added to the filter, and can be measured by weighing the filter before and after the powder is applied to it.

[0156] In this specification, the term "d" 50 "(by volume)" refers to Malvern products with Aero s dispersion units available from Malvern Panalytical Ltd., Malvern, UK. 3000 measured d 50(By volume) Measurement results. Dispersion conditions: air pressure = 2 bar, feed rate = 65%, hopper gap = 1.2 mm. According to Malvern The instructions in the 3000 user manual provide settings for the refractive index and absorption parameters.

[0157] As used herein, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” include plural references. The use of the term “comprising” is intended to be interpreted as including such features but not excluding other features, and also to include feature options that must be limited to those features described. In other words, the term also includes the limitations “consistently made of” (intended to indicate that certain additional components may be present, provided that they do not substantially affect the essential characteristics of the described feature) and “consisting of” (intended to indicate that other features may be excluded such that if these components were expressed as percentages of their proportions, they would total 100%, taking into account any unavoidable impurities), unless the context clearly indicates otherwise.

[0158] The detailed description above has been provided by way of explanation and illustration and is not intended to limit the scope of the appended claims. Many variations of the presently preferred embodiments shown herein will be apparent to those skilled in the art and remain within the scope of the appended claims and their equivalents.

Claims

1. A method for forming an inorganic oxide coating on a solid article used for treating waste gas, the method comprising: A porous monolithic article is provided, the porous monolithic article comprising a plurality of channels for the passage of exhaust gas, each channel having a gas contact surface; Inorganic particles and organosilicon resin are sprayed as dry particulate aerosols onto the gas contact surface to form a coating. as well as The coating is calcined to provide a coated monolithic article. The organosilicon resin described herein has the formula [R] x SiX y O z ] n , where R is an alkyl or aryl group, X is a functional group bonded to silicon, and z is greater than 1 and less than 2.

2. The method according to claim 1, wherein the bulk material product is a bulk filter and / or a catalyst product.

3. The method according to claim 1, wherein the integral material product is a wall-flow filter.

4. The method according to claim 1, wherein the integral product is a catalyst wall-flow filter.

5. The method according to any one of claims 1 to 4, comprising any one of the following: (i) The inorganic particles are sprayed as a first dry particulate aerosol onto the gas contact surface to form an inorganic particle layer, and then the organosilicon resin is sprayed as a second dry particulate aerosol onto the inorganic particle layer to form the coating; or (ii) The mixture of the inorganic particles and the organosilicon resin is sprayed as a dry particulate aerosol onto the gas contact surface to form the coating.

6. The method according to any one of claims 1 to 4, wherein the silicone resin has a molecular weight greater than 1,000 and / or less than 500,000.

7. The method according to any one of claims 1 to 4, wherein the silicone resin has a molecular weight greater than 2,000 and / or less than 500,000.

8. The method according to any one of claims 1 to 4, wherein the silicone resin has a molecular weight greater than 5,000 and / or less than 500,000.

9. The method according to any one of claims 1 to 4, wherein the silicone resin has a molecular weight greater than 10,000 and / or less than 500,000.

10. The method according to any one of claims 1 to 4, wherein the silicone resin has a molecular weight greater than 1,000 and / or less than 200,000.

11. The method according to any one of claims 1 to 4, wherein the silicone resin has a molecular weight greater than 2,000 and / or less than 200,000.

12. The method according to any one of claims 1 to 4, wherein the silicone resin has a molecular weight greater than 5,000 and / or less than 200,000.

13. The method according to any one of claims 1 to 4, wherein the silicone resin has a molecular weight greater than 10,000 and / or less than 200,000.

14. The method according to any one of claims 1 to 4, wherein the silicone resin has a glass transition temperature (Tg) greater than 30°C and / or less than 100°C.

15. The method according to any one of claims 1 to 4, wherein the silicone resin has a glass transition temperature (Tg) greater than 35°C and / or less than 100°C.

16. The method according to any one of claims 1 to 4, wherein the silicone resin has a glass transition temperature (Tg) greater than 30°C and / or less than 80°C.

17. The method according to any one of claims 1 to 4, wherein the silicone resin has a glass transition temperature (Tg) greater than 35°C and / or less than 80°C.

18. The method of claim 1, wherein y is less than 1, and / or wherein y is less than x.

19. The method according to any one of claims 1 to 4 and 6, wherein the silicone resin has a crosslinking degree of greater than 55% and / or less than 85%.

20. The method according to any one of claims 1 to 4 and 6, wherein the silicone resin has a crosslinking degree of greater than 60% and / or less than 85%.

21. The method according to any one of claims 1 to 4 and 6, wherein the silicone resin has a crosslinking degree of greater than 65% and / or less than 85%.

22. The method according to any one of claims 1 to 4 and 6, wherein the silicone resin has a crosslinking degree of greater than 55% and / or less than 80%.

23. The method according to any one of claims 1 to 4 and 6, wherein the silicone resin has a crosslinking degree of greater than 60% and / or less than 80%.

24. The method according to any one of claims 1 to 4 and 6, wherein the silicone resin has a crosslinking degree of greater than 65% and / or less than 80%.

25. The method according to any one of claims 1 to 4 and 18, wherein R is one or more of C1-C6 alkyl and phenyl.

26. The method according to any one of claims 1 to 4 and 18, wherein R is one or more of a straight-chain C1-C6 alkyl group and a phenyl group.

27. The method according to any one of claims 1 to 4 and 18, wherein R is one or both of methyl and phenyl.

28. The method according to any one of claims 1 to 4 and 18, wherein R is methyl.

29. The method according to any one of claims 1 to 4 and 18, wherein X is one or more of H, OH, Cl and C1-C6 alkoxy groups.

30. The method according to any one of claims 1 to 4 and 18, wherein X is one or more of OH and C1-C6 alkoxy groups.

31. The method according to any one of claims 1 to 4 and 18, wherein X is one or both of OH and ethoxy.

32. The method according to any one of claims 1 to 4, wherein the silica content of the organosilicon resin is greater than 50% by weight.

33. The method according to any one of claims 1 to 4, wherein the silica content of the organosilicon resin is greater than 60% by weight.

34. The method according to any one of claims 1 to 4, wherein the silica content of the organosilicon resin is greater than 70% by weight.

35. The method according to any one of claims 1 to 4, wherein the silica content of the organosilicon resin is greater than 80% by weight.

36. The method according to any one of claims 1 to 4, wherein the inorganic particles are selected from the group consisting of zeolites, refractory oxides, and mixtures thereof.

37. The method according to claim 36, wherein the inorganic particles are refractory oxide particles, the refractory oxide particles comprising calcium aluminate, pyrolytic alumina, pyrolytic silica, pyrolytic titanium dioxide, pyrolytic zirconium oxide, pyrolytic cerium dioxide, alumina aerogel, silica aerogel, titanium dioxide aerogel, zirconium oxide aerogel, cerium dioxide aerogel, or mixtures thereof.

38. The method according to any one of claims 1 to 4, wherein the inorganic particles have a di of greater than 0.2 µm and / or less than 50 µm by volume. 50 .

39. The method according to any one of claims 1 to 4, wherein the inorganic particles have a di of greater than 0.2 µm and / or less than 25 µm by volume. 50 .

40. The method according to any one of claims 1 to 4, wherein calcination comprises heating to a temperature of at least 200°C and / or at most 600°C.

41. The method according to any one of claims 1 to 4, wherein calcination comprises heating to a temperature of at least 300°C and / or at most 600°C.

42. The method according to any one of claims 1 to 4, wherein calcination comprises heating to a temperature of at least 400°C and / or at most 600°C.

43. The method according to any one of claims 1 to 4, wherein calcination comprises heating to a temperature of at least 200°C and / or at most 550°C.

44. The method according to any one of claims 1 to 4, wherein calcination comprises heating to a temperature of at least 300°C and / or at most 550°C.

45. The method according to any one of claims 1 to 4, wherein calcination comprises heating to a temperature of at least 400°C and / or at most 550°C.

46. ​​The method according to any one of claims 1 to 4, wherein calcination comprises heating to a temperature of at least 200°C and / or at a temperature of up to 530°C.

47. The method according to any one of claims 1 to 4, wherein calcination comprises heating to a temperature of at least 300°C and / or at most 530°C.

48. The method according to any one of claims 1 to 4, wherein calcination comprises heating to a temperature of at least 400°C and / or at most 530°C.

49. The method according to any one of claims 1 to 4, wherein the monolithic article comprises one or more platinum group metals.

50. The method according to any one of claims 1 to 4, wherein the dry particulate aerosol has a tapped density of less than 1.5 g / cm³. 3 The dry microparticle composition is formed.

51. The method according to any one of claims 1 to 4, wherein the mixture of the inorganic particles and the silicone resin is sprayed as a dry particulate aerosol onto the gas contact surface to form the coating, and wherein in the mixture, the weight ratio of the inorganic particles to the silicone resin is greater than 0.5 and / or less than 4.

52. The method according to any one of claims 1 to 4, wherein the mixture of the inorganic particles and the silicone resin is sprayed as a dry particulate aerosol onto the gas contact surface to form the coating, and wherein in the mixture, the weight ratio of the inorganic particles to the silicone resin is greater than 0.7 and / or less than 4.

53. The method according to any one of claims 1 to 4, wherein the mixture of the inorganic particles and the silicone resin is sprayed as a dry particulate aerosol onto the gas contact surface to form the coating, and wherein in the mixture, the weight ratio of the inorganic particles to the silicone resin is greater than 0.9 and / or less than 4.

54. The method according to any one of claims 1 to 4, wherein the mixture of the inorganic particles and the silicone resin is sprayed as a dry particulate aerosol onto the gas contact surface to form the coating, and wherein in the mixture, the weight ratio of the inorganic particles to the silicone resin is greater than 0.5 and / or less than 3.

55. The method according to any one of claims 1 to 4, wherein the mixture of the inorganic particles and the silicone resin is sprayed as a dry particulate aerosol onto the gas contact surface to form the coating, and wherein in the mixture, the weight ratio of the inorganic particles to the silicone resin is greater than 0.7 and / or less than 3.

56. The method according to any one of claims 1 to 4, wherein the mixture of the inorganic particles and the silicone resin is sprayed as a dry particulate aerosol onto the gas contact surface to form the coating, and wherein in the mixture, the weight ratio of the inorganic particles to the silicone resin is greater than 0.9 and / or less than 3.

57. The method according to any one of claims 1 to 4, wherein the mixture of the inorganic particles and the silicone resin is sprayed as a dry particulate aerosol onto the gas contact surface to form the coating, and wherein the weight ratio of the inorganic particles to the silicone resin in the mixture is greater than 0.5 and / or less than 2.

5.

58. The method according to any one of claims 1 to 4, wherein the mixture of the inorganic particles and the silicone resin is sprayed as a dry particulate aerosol onto the gas contact surface to form the coating, and wherein the weight ratio of the inorganic particles to the silicone resin in the mixture is greater than 0.7 and / or less than 2.

5.

59. The method according to any one of claims 1 to 4, wherein the mixture of the inorganic particles and the silicone resin is sprayed as a dry particulate aerosol onto the gas contact surface to form the coating, and wherein in the mixture, the weight ratio of the inorganic particles to the silicone resin is greater than 0.9 and / or less than 2.

5.

60. An uncalcined porous monolithic article for forming a monolithic article for treating waste gas, the uncalcined porous monolithic article comprising a plurality of channels and containing a dry particulate composition comprising inorganic particles and an organosilicon resin, the dry particulate composition being located within the channels and / or pores of the uncalcined porous monolithic article, wherein the organosilicon resin has the formula [R x SiX y O z ] n , where R is an alkyl or aryl group, X is a functional group bonded to silicon, and z is greater than 1 and less than 2.

61. The uncalcined porous monolithic article according to claim 60, wherein the mass loading of the dry particulate composition is less than 50 g / L.

62. The uncalcined porous monolithic article according to claim 60, wherein the mass loading of the dry particulate composition is less than 30 g / L.

63. An uncalcined porous monolithic article for forming a monolithic article for treating waste gas, said monolithic article being obtainable by a method comprising the following steps: A porous monolithic article is provided, the porous monolithic article comprising a plurality of channels for the passage of exhaust gas, each channel having a gas contact surface; Inorganic particles and organosilicon resin are sprayed as dry particulate aerosols onto the gas contact surface to form a coating. The organosilicon resin described herein has the formula [R] x SiX y O z ] n , where R is an alkyl or aryl group, X is a functional group bonded to silicon, and z is greater than 1 and less than 2.

64. A coated monolithic article for treating waste gas, said coated monolithic article being obtainable by the method according to any one of claims 1 to 51.

65. A vehicle exhaust system comprising a coated monolithic article as described in claim 64.

Images