Coatings on monolithic articles

Abstract

The present disclosure relates to coated monolith articles for filtering particulate matter from exhaust gases. The monolith article has an inlet end and an outlet end and includes a coating. The article includes an inorganic oxide applied to the inlet end of the article and a washcoat coating applied to the outlet end of the article. The present disclosure also relates to methods of forming the coated monolith articles described herein, and to exhaust systems having the coated monolith articles described herein.

Description

[Technical Field]

[0001] The present disclosure relates to a coated monolith article for filtering particulate matter from exhaust gases. The monolith article has an inlet end and an outlet end and includes a coating. The article includes an inorganic oxide applied to the inlet end of the article and a washcoat coating applied to the outlet end of the article. The present disclosure also relates to methods of forming the coated monolith articles described herein, and to exhaust systems having the coated monolith articles described herein. [Background technology]

[0002] There are concerns regarding emissions of particulate matter (PM), commonly referred to as soot, from internal combustion engines, particularly diesel and gasoline engines for automotive applications. The main concerns relate to potential health effects, specifically those related to very small particles with sizes in the nanometer range.

[0003] Diesel particulate filters (DPFs) and gasoline particulate filters (GPFs) are fabricated using a variety of materials, including sintered metal, ceramic, or metal fiber. However, the most common type in practical mass production is the wall-flow variety, made from porous ceramic materials fabricated in the form of a monolithic array of many small channels extending along the length of the body. The alternating channels are plugged at one end, forcing exhaust gases through the porous ceramic channel walls, which prevent the majority of particulates from passing through, allowing only filtered gases to enter the environment. Commercially produced ceramic wall-flow filters include those made from cordierite, various forms of silicon carbide, and aluminum titanate. The actual shape and dimensions of practical filters on vehicles, as well as characteristics such as the thickness and porosity of the channel walls, depend on the application involved. The average size of the pores in the filter channel walls through which gases pass is typically in the range of 5 to 50 μm, usually around 15 μm. In sharp contrast, most diesel exhaust particulate matter from modern passenger car high speed diesel engines is very small in size, eg, 10-200 nm.

[0004] Some PM may be retained within the pore structure within the filter wall, which in some applications may gradually build up until the pores are bridged by a network of PM, which then allows a cake of particulates to readily form on the inner walls of the filter channels. The particulate cake is an excellent filter medium, and its presence results in very high filtration efficiency. In some applications, soot is continuously burned on the filter as it is deposited, which prevents the particulate cake from building up on the filter.

[0005] Some filters, such as light-duty diesel particulate filters, require periodic removal of trapped PM from the filter to prevent excessive backpressure buildup, which can be detrimental to engine performance and cause poor fuel economy. In diesel applications, retained PM is removed from the filter by burning it in air during a process during which the amount of available air and the amount of excess fuel used to achieve the high temperatures necessary to ignite the retained PM are very carefully controlled. Toward the end of this process, typically called regeneration, removal of the last remaining particulates in the filter can significantly reduce filtration efficiency and lead to the burst release of many small particles into the environment. Thus, filters can have low filtration efficiency when they are first used, after each subsequent regeneration event, and during the latter part of each regeneration process.

[0006] It is therefore desirable to constantly improve and / or maintain filtration efficiency, for example during the initial life of the filter when first used, and / or during and immediately after regeneration, and / or when soot builds up on the filter.

[0007] WO 2021 / 028691 describes a method for coating a filter comprising a porous substrate having an inlet surface and an outlet surface, the inlet surface being separated from the outlet surface by a porous structure, the filter being coated with a dry powder that is applied through the inlet surface of the filter.

[0008] WO 2021 / 165658 describes an apparatus and method for coating a filter comprising a porous substrate having an inlet surface and an outlet surface, the filter being coated through the inlet surface of the filter with a dry powder, the dry powder comprising a metal compound for forming a metal oxide by pyrolysis.

[0009] WO 2011 / 151711 describes a method for making a filter comprising a porous substrate having an inlet surface and an outlet surface, the inlet surface being separated from the outlet surface by a porous structure comprising pores of a first average pore size. The inlet surface comprises a crosslinked network comprising interconnected particles of a refractory material spanning the pores of the porous structure. The method includes contacting the inlet surface of the filter substrate with an aerosol comprising the refractory material in dry powder form. Summary of the Invention

[0010] In a first aspect, the present disclosure provides a coated monolith article for filtering particulate matter from exhaust gases.

[0011] The monolith article includes an inlet end and an outlet end and a coating, the coating comprising: a) an inorganic oxide coating applied to the inlet end of the article; b) a washcoat coating applied to the outlet end of the article.

[0012] In a further aspect, a method of forming a monolithic article (e.g., a monolithic article described herein) includes: i) providing a monolithic article having an inlet end and an outlet end; ii) applying an inorganic oxide coating to the inlet end; iii) optionally drying and / or calcining the inorganic coating; iv) applying a washcoat coating to the outlet end; v) optionally drying / firing the resulting article.

[0013] In a further aspect, an exhaust gas system is provided comprising a coated monolith article (e.g., a coated monolith article described herein or made by a method described herein) and, optionally, a combustion engine.

[0014] In a further aspect, a method for treating an exhaust gas is provided, the method comprising contacting the exhaust gas with a coated monolith article (e.g., a coated monolith article described herein or made by a method described herein).

[0015] Applying an inorganic coating as a first step and then using a washcoat was not thought possible at the time of this invention because the inorganic coating would not be stable during the application of the subsequent washcoat. It has been found that applying an inorganic coating as a first step provides less control over the final backpressure and less control over the washcoat location, even when the inorganic coating is tailored to be stable during the application of the washcoat. The inventors have surprisingly found that by tailoring the composition of the inorganic coating, the final backpressure and washcoat location can be controlled, and the inorganic coating is stable to the application of the subsequent washcoat.

[0016] The coated monolith articles described herein (or made by the methods described herein) have improved properties over coated monolith articles of the prior art. For example, coated monolith articles according to the present invention have improved filtration efficiency without experiencing the increased backpressure typically associated with improved filtration efficiency. The coated monolith articles of the present invention have low backpressure and high filtration efficiency. [Brief explanation of the drawings]

[0017] [Figure 1] 1 shows a coated monolith article according to the present invention. [Figure 2] The filtration efficiencies of Comparative Examples 1 and 2 and Sample 3 are shown. [Figure 3] shows the mass loading and cold flow back pressure for Comparative Examples 1 and 2, and Sample 3. [Figure 4] The filtration efficiencies of Comparative Examples 1 and 2 and Sample 3 are shown. DETAILED DESCRIPTION OF THE INVENTION

[0018] In a first aspect, the present disclosure provides a coated monolith article for filtering particulate matter from exhaust gases.

[0019] The monolith article includes an inlet end and an outlet end and a coating, the coating comprising: a) an inorganic oxide coating applied to the inlet end of the article; b) a washcoat coating applied to the outlet end of the article.

[0020] Monolithic Objects The monolithic articles described herein may comprise a plurality of channels for the passage of exhaust gases, each channel having a gas contact surface. Monolithic articles are well known in the art.

[0021] The monolith article may sometimes be referred to as a substrate, preferably a honeycomb substrate, more preferably a ceramic honeycomb substrate. Such a substrate includes a plurality of channels suitable for the passage of exhaust gases. The channels are parallel and extend from an inlet end (or first end) to an outlet end (or second end), i.e., the channels extend axially through the article. Typically, the channels have a square cross-section, although any known monolith design may be used.

[0022] The monolithic article / substrate may be formed from, for example, sintered metal, ceramic, or metal fibers, etc. For example, the article may be formed from cordierite, various forms of silicon carbide, or aluminum titanate.

[0023] In some embodiments, the monolith article is a monolith filter. It is particularly preferred that the monolith filter is a wall-flow filter (which may also be known as a wall-flow monolith article). Wall-flow filters are well known and typically have adjacent channels alternately blocked at each end of the monolith article, such that in use, exhaust gas passes along the inlet channel (i.e., the channel that is open at the inlet end of the monolith article to receive the exhaust gas) and passes through the channel wall into the adjacent outlet channel (i.e., the channel that is open at the outlet end of the monolith article).

[0024] The channel walls may have a distribution of pores that provides the required porosity to the monolith article, with the average size of the pores in the channel walls, e.g., filter walls, typically being in the range of 5 to 50 μm. Each channel may have a gas-contacting surface, i.e., a surface suitable for contact with, for example, exhaust gases, in use. The surface may be provided by the channel wall surface and / or the pores contained therein.

[0025] In another particularly preferred embodiment, the monolith article is a catalytic article (i.e., a catalytic filter). Catalytic porous monolith articles are well known and are used for the oxidation, NO x The catalytic article also exhibits catalytic functionality, such as scavenging or selective catalytic reduction activity. x Absorbents, oxidation catalysts, selective reduction catalysts (SCR), hydrocarbon traps, and lean NO x The catalyst may be selected from:

[0026] In another particularly preferred embodiment, the monolith article is a catalytic wall-flow filter. As a result, the article can be used in a variety of applications, such as, for example, a catalyzed soot filter (CSF), a selective catalytic reduction filter (SCRF), a lean NO filter, or a catalyzed wall-flow filter. xTrap filter (lean NO x The filter may be a selective catalytic reduction (SCR) catalyst and an ammonia slip catalyst (ASC) filter, or a combination of two or more thereof (e.g., a filter including a selective catalytic reduction (SCR) catalyst and an ammonia slip catalyst (ASC)).

[0027] In another particularly preferred embodiment, the monolith article is a gasoline particulate filter that is a catalytic wall-flow filter comprising a TWC catalyst. Generally, gasoline particulate filters comprise a platinum group metal selected from the group consisting of Pt, Pd, Rh and mixtures thereof, an oxygen storage capacity (OSC) material, and optionally an inorganic support material.

[0028] The shape and dimensions of the filter, such as its channel wall thickness and its porosity, may vary depending on the intended use of the filter. The filter may be configured for use with an internal combustion engine to filter exhaust gases emitted by the internal combustion engine. The internal combustion engine may be a gasoline spark-ignition engine. However, the filter finds particular application when configured for use with internal combustion engines in the form of diesel or gasoline engines.

[0029] The wall-flow filter may be an asymmetric wall-flow filter. Asymmetric wall-flow filter designs are known, for example, from WO 2005 / 030365, which discloses a honeycomb filter including an array of interconnected porous walls defining an array of first and second channels. The first channels are adjacent to the second channels on their sides and have a larger hydraulic diameter than the second channels. The first channels have a square cross-section, and the corners of the first channels are shaped such that the thickness of the porous walls adjacent the corners of the first channels is comparable to the thickness of the porous walls adjacent the edges of the first and second channels. In use, the first channel with the larger hydraulic diameter is positioned upstream. Society of Automotive Engineers SAE Technical Paper Series 2007-01-0656 explains that "there is a pressure loss penalty in the clean state of ACT designs [in catalyzed asymmetric cell technology (ACT) wall-flow filters] due to gas contraction and expansion at the inlet and outlet of the filter channels. However, the filter can only remain completely clean (fully regenerated) for a short period of time during on-vehicle operation." WO 2005 / 030365 also explains that advantages of the asymmetric filter design include an increase in the effective surface area available for collecting soot and ash particles at the inlet section of the honeycomb filter, thus increasing the overall storage capacity of the honeycomb filter. The common general knowledge textbook "Catalytic Air Pollution Control - Commercial Technology", 3rd Edition, Ronald M. Heck et al., John Wiley & Sons, Inc., Hoboken, NJ, USA (2009) pp. 338-340 explains that "Such [asymmetric filter] channel designs allow for higher ash storage capacity combined with lower back pressure after ash loading due to the larger hydraulic diameter and larger inlet open volume. The ACT design also helps maintain the mechanical and thermal durability of the filter."

[0030] Inorganic Oxide Coating The inorganic oxide coatings described herein may include inorganic particles, including aluminosilicate zeolites, and a silicone resin.

[0031] The inorganic particles may comprise an aluminosilicate zeolite having a SAR greater than 10:1, greater than 20:1, greater than 50:1, greater than 75:1, or greater than 100:1. The aluminosilicate zeolite preferably has a SAR greater than 200:1, more preferably greater than 300:1, even more preferably greater than 400:1, and most preferably greater than 500:1. In some embodiments, the aluminosilicate zeolite has a SAR greater than 1000:1.

[0032] ABW, ACO, AEI, AEL, AEN, AET, AFG, AFI, AFN, AFO, AFG R, 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. CFI, SGF, CGS, CHA, CHI, CLO, CON, CZP, DAC, DDR, DFO, DFT, DOH, DON, EA B, 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, M EL, MEP, MER, MFI, MFS, MON, MOR, MOZ, MSO, MTF, MTN, MTT, 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, S AV, SBE, SBS, SBT, SFE, SFF, SFG, SFH, SFN, SFO, SFW, SGT, SOD, SOS, SS Y, STF, STI, STT, TER, THO, TON, TSC, UEI, UFI, UOZ, USI, UTL, VET, WI, V NI, VSV, WIE, WEN, YUG, ZON This is a very nice and relaxed scent AEI, AFT, AFV, AFX, AVL, BEA, CHA, DDR, EAB, EE I、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 have a slightly larger range.In some embodiments, the aluminosilicate zeolite can have a framework type selected from the group including (or consisting of): AEI, BEA, CHA, FAU (e.g., zeolite Y), and MFI. In some embodiments, the aluminosilicate zeolite has a BEA framework type. In some embodiments, the aluminosilicate zeolite has an MFI framework type. In some embodiments, the aluminosilicate has an FAU framework type. In some embodiments, the zeolite is zeolite Y.

[0033] In addition to the aluminosilicate zeolite, the inorganic particles may include a second zeolite material. Examples of suitable second zeolite materials include silicate zeolites, aluminosilicate zeolites, metal-substituted aluminosilicate zeolites, AlPO, MeAlPO, SAPO, MeAPSO, etc. The second zeolite material may be selected from the group consisting of 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, CFI, SGF, CGS, CHA, etc. , 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, MTT, MTW, MWF, MWW, NA B, NAT, NES, NON, NPO, NPT, NSI, OBW, OFF, OSI, OSO, OWE, PAR, PAU, PHI, PON, RHO, RON, RRO, RSN, RTE, RTH, RUT, RW The skeletal type may be selected from R, 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 a combination thereof.

[0034] The inorganic particles may include refractory oxide particles that may be based on an oxide selected from the group including (or consisting of) alumina, silica, zirconia, ceria, chromia, magnesia, calcia, titania, and mixed oxides of any two or more thereof. Preferably, the refractory oxide particles include calcium aluminate, fumed alumina, fumed silica, fumed titania, fumed zirconia, fumed ceria, alumina aerogel, silica aerogel, titania aerogel, zirconia aerogel, ceria aerogel, or mixtures thereof. One or more fumed refractory powders (refractory oxide particles) may be produced by an exothermic process, such as flame pyrolysis.

[0035] The amount of aluminosilicate zeolite present in the inorganic particles can be 10 to 99 wt%, preferably 50 to 99 wt%, more preferably 80 to 99 wt%, and most preferably 90 to 99 wt%. In some embodiments, the inorganic particles comprise (or consist of) an aluminosilicate zeolite. In some embodiments, the inorganic particles comprise (or consist of) an aluminosilicate zeolite having an SAR greater than 100:1. In some embodiments, the inorganic particles comprise (or consist of) an aluminosilicate zeolite having an SAR greater than 200:1. In some embodiments, the inorganic particles comprise (or consist of) an aluminosilicate zeolite having an SAR greater than 300:1. In some embodiments, the inorganic particles comprise (or consist of) an aluminosilicate zeolite having an SAR greater than 400:1. In some embodiments, the inorganic particles comprise (or consist of) an aluminosilicate zeolite having an SAR greater than 500:1. In some embodiments, the inorganic particles comprise (or consist of) an aluminosilicate zeolite having an SAR greater than 1000:1.

[0036] Silicone resins are known and are branched, cage-like oligosiloxanes and polysiloxanes. Branching in silicone resins arises from the presence of so-called "T" and / or "Q" units in the resin, which refer to RSiO3 and SiO4 units, respectively (R is an alkyl or aryl group), with additional silicon units bonded to oxygen atoms. "M" units, i.e., R3SiO units, are terminal units where the oxygen atom provides the bond to the resin backbone. Similarly, "D" units, i.e., R2SiO2 units, provide linear connectivity across two oxygen atoms. One well-known unbranched and linear polysiloxane is polydimethylsiloxane (PDMS, i.e., (Me2SiO) n )

[0037] Preferably, the silicone resin is solid at room temperature (e.g., about 25°C). Thus, the silicone resin preferably has a melting point above 25°C, preferably above 30°C, more preferably above 35°C. Preferably, the melting point of the silicone resin is 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, the melting point of PDMS is about -40°C. WO 2011 / 151711 discloses binding powders in place by treating them with polydimethylsiloxane, which forms silica when hydrolyzed at a sufficiently high temperature.

[0038] Similarly, the inventors have found that it is preferred that the silicone resin 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 being bound by theory, the inventors believe that silicone resins having such melting points and / or glass transition temperatures are particularly suitable for powder coating processes, i.e., for effectively dispersing particulates onto the monolith article together with inorganic particles, yet are low enough to allow low temperature firing, thereby effectively and efficiently adhering the inorganic particles to the gas-contacting surfaces of the channel walls.

[0039] Preferably, the silicone resin has a molecular weight of more than 1,000, preferably more than 2,000, preferably more than 5,000, preferably more than 10,000, and / or a molecular weight of less than 500,000, preferably less than 200,000.

[0040] As used herein, molecular weight refers to the weight average molecular weight (M), which can be measured using any conventional means in the art. W ) refers to a silicone resin having a molecular weight of 1,000 to 10,000, preferably 1,000 to 5,000, preferably 1,200 to 3,500, e.g., 1,500 to 2,000. In some embodiments, particularly those described herein in which the silicone resin includes hydroxy functional groups, the molecular weight can be relatively low because the hydrogen bonding provided by the hydroxy functional groups provides 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 can be 1,000 to 10,000, preferably 1,000 to 5,000, preferably 1,200 to 3,500, e.g., 1,500 to 2,000. Silicone resins having a molecular weight of less than 1,000 are typically liquids and are less preferred because they are not suitable for dry spraying or do not have as much branching as larger molecules, which are believed to provide enhanced bonding of inorganic particles to monolithic articles.

[0041] Nevertheless, the molecular weight of the silicone resin may preferably be 15,000 to 150,000, preferably 20,000 to 120,000, preferably 60,000 to 100,000. Some preferred resins have Mw of 8,000 to 15,000, some of 20,000 to 60,000, and others of 80,000 to 120,000.

[0042] The silicone resin has the formula [R x Six y O z ] nwhere R is an alkyl or aryl group, X is a silicon-bonded functional group, and z is greater than 1 and less than 2. As will be appreciated, n is large enough to provide the necessary oligomers or polymers for silicone resins, especially resins that are solid at room temperature. Depending on the molecular weight of the R and X groups, n greater than 10 will provide for M greater than 1,000. W can be achieved, and when n is greater than 100, M greater than 10,000 W can be obtained, and when n is greater than 1,000, M can be obtained W can be achieved. Thus, n may preferably be greater than 10, greater than 100, or greater than 1,000.

[0043] As will be understood, R is an alkyl or aryl bonded to silicon, and X is a non-hydrocarbon functional group bonded to silicon. Similarly, since silicon is a tetravalent atom, it will be understood that x + y + 2z = 4. Since z = 2, x and y = 0, z is less than 2, and silica (i.e., silicon dioxide, (SiO2) n Similarly, where z=1 and x+y=2, z is greater than 1, providing a substituted polysiloxane (e.g., (RXSiO)) composed of "D" units that provide a linear resin (e.g., -O-(SiRX)-O-(SiRX)-O-). n ) provides. An example is polydimethylsiloxane. Thus, O refers to the oxygen that bridges two silicon atoms in the polymer backbone of the silicone resin.

[0044] Preferably, 0 < x + y < 2, preferably 0 < x + y ≤ 1.5, preferably 0 < x + y ≤ 1. In a preferred embodiment, x + y is 1, providing 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, when the polysilsesquioxane is a polyalkylsilsesquioxane such as polymethylsilsesquioxane (MeSiO 3 / 2 ) n etc., y is 0.

[0045] Typically, when present, X is one or more of H, hydroxy (OH), Cl, and C1-C6 alkoxy, preferably one or more of OH and C1-C6 alkoxy, and preferably, 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 can be a functional group that can be a reactive functional group such as aminyl (NH2, NR2), epoxy, acrylate, and vinyl, but these are less preferred because the presence of a hydroxy group or an alkoxy group is considered to provide more effective cross-linking during firing. As described above, any oxygen present in the terminal functional group does not contribute to the "O z " in the above formula that refers to the silicon cross-linking oxygen atom.

[0046] The inventors have found that the silicone resins described herein provide coated monolithic articles with the advantageous benefits of enhanced water resistance and improved thermal stability. Silicone resins have been found to be particularly advantageous for bonding inorganic particles to monolithic articles. Without being bound by theory, the inventors believe that the branched structure and physical properties of silicone resins allow the resin to initially melt during the firing process described herein, bond with the inorganic particles on the gas-contacting surfaces of the channels (either intimately or deposited thereon), and then begin to harden. As the resin hardens, it forms additional -Si-O-Si-O-Si- bridges / bonds, further increasing its branched structure. Additionally, the inventors believe that such bonds may also form with the gas-contacting surface (i.e., the monolithic article itself) along with the inorganic particles, further bonding the particles in place in the article, for example, by forming -Si-O-Al- bonds. As the temperature continues to increase during firing, the R and X groups are oxidized, leaving behind a silica (SiO) framework. Therefore, silicon and / or aluminum containing inorganic particles, such as zeolites, calcium aluminate, alumina and / or silica, may be preferred.

[0047] Preferably, the silicone resin has a degree of cross-linking greater than 55%, preferably greater than 60%, more preferably greater than 65%, and / or a degree of cross-linking less than 85%, preferably less than 80%.

[0048] As described herein, a compound of the formula [R x Six y O z ] n The silicon atoms of silicone resins, such as those described by the formula (I), can be in one of four coordination environments, namely, SiO(R / X)3, SiO2(R / X)2, SiO3(R / X), or SiO4, known in the art as "M," "D," "T," and "Q," respectively, given the tetravalent nature of silicon. Thus, the above formula can be expressed as aMbDcTdQ, where a+b+c+d=1 and the degree of crosslinking is [(a+2b+3c+4d) / 4]. *The relative ratio of the number of silicon atoms in each coordination environment can be described by standard spectroscopic techniques, such as multinuclear NMR spectroscopy, particularly 29 It can be determined using Si NMR spectroscopy. Alternatively, for commercially available silicone resins, the degree of crosslinking can be provided in the technical data sheet.

[0049] In other words, silicon dioxide (SiO2) is formed entirely from "Q" SiO4 units, in which each silicon atom is bonded to four connecting oxygen atoms. Thus, when d is 1, this gives silicon dioxide a 100% degree of crosslinking. On the other hand, as an example, PDMS is formed entirely from "D" Si(Me)2O2. Thus, when b is 1, this gives polydimethylsiloxane a 50% degree of crosslinking. Consequently, the silicone resin preferably has a degree of crosslinking between these two extremes and includes a mixture of such units. Thus, the silicone resin may preferably include (or consist of) MDT units, MTQ units, DTQ units, or DT units.

[0050] Preferably, R is one or more C1-C6 alkyl or phenyl groups. Due to the oligomeric or polymeric nature of silicone resins, the number of monomer units is typically large. There can be many instances of both the R and X groups, so that a silicone resin described by a single monomer unit can contain multiple different groups. As explained above with respect to the functional group X, X can preferably be both OH and ethoxy. Similarly, R can contain two or more C1-C6 alkyl and / or phenyl groups. Thus, when R is described by two or more groups, such as R' and R'', the formula of the silicone resin can be written as [R' x’ R'' x’’ Six y O z ] n where x'+x''=x. This applies equally to the functional group X.

[0051] Preferably, R is one or more of a linear or branched alkyl and a phenyl, one or more of a linear alkyl and a phenyl, more preferably one or both of a methyl and a phenyl. In some preferred embodiments where R is both a methyl and a phenyl, the phenyl to methyl ratio is less than 2, preferably less than 1.5, preferably less than 1, preferably less than 0.5. In some embodiments, R is a phenyl. More preferably, R is a methyl (i.e., the ratio is 0).

[0052] Smaller organic groups such as methyl, methoxy, and ethoxy for the R and X groups are particularly preferred because they increase the SiO content of the starting silicone resin and reduce weight loss during baking. Additionally, smoke and volatile material (such as H2O, CO2, and other volatile organics) loss during baking is reduced.

[0053] Thus, it is preferred that the silicon dioxide content of the silicone resin is greater than 50% by weight, preferably greater than 60% by weight, preferably greater than 70% by weight, preferably greater than 80% by weight. Silicon dioxide content can also be referred to as ash content, which is the weight of the product remaining after complete oxidation (in this case, the product is silicon dioxide) by weight of the starting silicone resin. For example, oxidation can be carried out at 1000°C. Alternatively, the silicon dioxide content can be obtained from the technical data sheet of a suitable commercially available silicone resin. Alternatively, the silicon dioxide content can be calculated based on the complete oxidation of silicon to silicon dioxide and the chemical formula of the resin. By way of example only, polymethylsilsesquioxane (MeSiO 3 / 2 ) n is about 42.7% by weight of silicon, based on the weight of the silicone resin having a formula weight of 66.1 and an atomic weight of silicon of 28.1. The silicon dioxide has a formula weight of 60.1, which is about 2.1 times greater than the formula weight of silicon. Therefore, the silicon dioxide content of the polymethylsilsesquioxane is 2.1 * 42.7=89.7% by weight (i.e., by weight of the silicone resin).

[0054] One particularly preferred silicone resin for use in the method of the present invention is a highly crosslinked ethoxylated poly(dimethylsiloxane) having a silicon dioxide content of about 82% by weight and a melting point of 35°C to 55°C.

[0055] Preferably, the inorganic particles and / or silicone resin particles have a d by volume of more than 0.2 μm, preferably more 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, preferably less than 10 μm. 50 It has.

[0056] Preferably, the total inorganic oxide coating can be applied to the monolith article at a mass loading of less than 50 g / L, preferably less than 30 g / L. In a preferred embodiment, the total mass loading of the inorganic oxide coating is between 1 g / L and 25 g / L, for example, between 2 and 20 g / L, or preferably between 3 and 15 g / L. Preferably, the mass loading of the inorganic particles is at least 1 g / L and / or less than 25 g / L. Preferably, the mass loading of the silicone resin is at least 1 g / L and / or less than 25 g / L. In a preferred embodiment, the mass loading of the inorganic particles is between 1 g / L and 15 g / L and / or the mass loading of the silicone resin is between 1 g / L and 15 g / L. As an example, if the weight ratio of inorganic particles to silicone resin is 1:1, the loading of the inorganic particles can be 5 g / L and the loading of the silicone resin can be 5 g / L, giving a total loading of the inorganic oxide coating of 10 g / L. As an example, if the ratio is 2:1, the inorganic particle loading may be 10 g / L and the silicone resin loading may be 5 g / L, giving a total loading of 15 g / L.

[0057] In some embodiments, the ratio of inorganic particles to silicone resin in the inorganic oxide coating is from 0.5:1 to 5:1, preferably from 1:1 to 4:1, for example, about 2:1 or 3:1.

[0058] Wash Coat Coating The washcoat coatings described herein may include an oxygen storage capacity (OSC) material, an inorganic oxide support, a precious metal, and / or a rheology modifier.

[0059] "Oxygen storage capacity" refers to the ability of a material used as an oxygen storage material in a catalyst to store oxygen under lean conditions and release oxygen under rich conditions.

[0060] Examples of OSC materials that can be used in washcoat coatings include Al2O3, SiO2, TiO2, CeO2, ZrO2, V2O5, La2O3, Nd2O3, and Pr6O 11 , HfO, and zeolites (e.g., zeolites described herein). In preferred embodiments, the OSC material present in the washcoat coating comprises one or more mixed oxides, such as a mixed oxide of cerium and zirconium, a mixed oxide of cerium, zirconium, and aluminum, a mixed oxide of cerium, zirconium, and neodymium, a mixed oxide of cerium, zirconium, and praseodymium, or a mixed oxide of cerium, zirconium, lanthanum, and neodymium. The term "mixed oxide," as used herein, generally refers to a mixture of oxides in a single phase, as conventionally known in the art. In further preferred embodiments, the washcoat coating comprises one or more OSC materials selected from a mixed oxide of cerium and zirconium, a mixed oxide of cerium, zirconium, and neodymium, a mixed oxide of cerium, zirconium, lanthanum, and neodymium, or a mixed oxide of cerium, zirconium, lanthanum, hafnium, and neodymium.

[0061] The amount of OSC material in the washcoat coating can be 5-50 wt %, preferably 10-30 wt %, based on the total weight of the washcoat coating.

[0062] Examples of inorganic oxide supports can be oxides of elements from Groups 2, 3, 4, 5, 13, and 14. The inorganic oxide support is preferably a refractory oxide that exhibits chemical and physical stability at high temperatures, such as temperatures associated with the exhaust of a gasoline engine. The inorganic oxide support can be selected from the group consisting of alumina, silica, titania, and mixed or composite oxides thereof. More preferably, the inorganic oxide support is alumina. In one embodiment, the inorganic oxide support is γ-alumina. The γ-alumina used as the inorganic oxide support preferably has an average particle size of 1 to 10 μm, more preferably 2 to 8 μm. In another embodiment, the inorganic oxide support is nano-alumina. The nano-alumina used as the inorganic oxide support preferably has an average particle size of less than 1 μm.

[0063] The inorganic oxide support may be doped with a dopant. The dopant may be selected from the group consisting of La, Sr, Si, Ba, Y, Pr, Nd, Ce, and mixtures thereof. Preferably, the dopant is La, Ba, Nd, or Ce. Most preferably, the dopant is La or Nd. The dopant content in the inorganic oxide support may be 1 to 30% by weight, preferably 2 to 25% by weight, and more preferably 3 to 20% by weight.

[0064] The amount of inorganic oxide support in the washcoat coating can be 2 to 30 wt %, preferably 5 to 20 wt %, based on the total weight of the washcoat coating.

[0065] Examples of noble metals that can be used in the washcoat coating include platinum group metals (such as Ru, Rh, Pt, Os, Ir, and Pd), Ag, Au, In, Re, Ge, Be, Ga, Te, Bi, and Hg. In a preferred embodiment, the noble metal that can be used in the washcoat coating is selected from the group including Pt, Pd, and Rh.

[0066] The amount of total precious metals in the washcoat coating can be 0.005 to 10 wt %, preferably 0.001 to 5 wt %, and more preferably 0.05 to 3.0 wt %, based on the total weight of the washcoat coating.

[0067] Examples of rheology modifiers that can be used in the washcoat coating include silanes, amines, acids, polysaccharides (such as starch, cellulose, galactomannan gum, xanthan gum, and curdlan), dispersible cellulose (e.g., Natrosol), TEAOH (tetraethylammonium hydroxide), Dispex, amino acids, beta-alanine, and ammonia. In a preferred embodiment, the rheology modifier used in the washcoat coating is selected from polysaccharides and amino acids, such as Natrosol and beta-alanine.

[0068] The washcoat coating can further comprise a C2-C6 aliphatic amino acid. Suitable C2-C6 aliphatic amino acids include 3-amino-propionic acid, L-alanine, glycine, serine, L-valine, and the like. Preferably, the C2-C6 aliphatic amino acid has the formula HO2C-(CH2) n An amino acid having -NH2, where n is 1 to 5, preferably 1 to 3. One preferred amino acid is 3-amino-propionic acid (n=2).

[0069] The amount of C2-C6 aliphatic amino acid in the washcoat coating can be 1-50 wt %, preferably 2-40 wt %, more preferably 3-30 wt %, or 5-25 wt %, based on the mass of solids in the washcoat coating.

[0070] The washcoat coating may further comprise additional components such as a metal hydroxide, a metal phosphate, a metal carbonate, or a mixture thereof. The metal hydroxide may be selected from magnesium hydroxide, calcium hydroxide, strontium hydroxide, and barium hydroxide. The metal phosphate may be selected from magnesium phosphate, calcium phosphate, strontium phosphate, and barium phosphate. The metal carbonate may be selected from magnesium carbonate, calcium carbonate, strontium carbonate, and barium carbonate. In a preferred embodiment, the washcoat coating comprises barium hydroxide.

[0071] In a preferred embodiment, the washcoat coating comprises ceria zirconia, alumina, a precious metal selected from Pd, Pt, or Rh, barium hydroxide, a rheology modifier, and a C2-C6 aliphatic amino acid (e.g., 3-amino-propionic acid). The washcoat coating can optionally additionally comprise lanthanum oxide and / or neodymium oxide.

[0072] Preferably, the total washcoat loading is 35-150 g / L, preferably 40-125 g / L, e.g., 50-100 g / L, 60-90 g / L, or 65-85 g / L. In alternative embodiments, the total washcoat loading is about 70, about 75, or about 80 g / L.

[0073] The washcoat coating may have a pH of 4-7, for example, 4.5-6.5, preferably 5-6.

[0074] The washcoat coating can have a conductivity of 1 to 100 mS, e.g., 2 to 50 mS, 3 to 30 mS, 5 to 25 mS, or 10 to 20 mS. In a preferred embodiment, the conductivity is 1 to 30 mS, e.g., 5 to 25 mS, 8 to 22 mS, 10 to 20 mS, or 12 to 18 mS.

[0075] Conductivity can be measured using a Cole Parmer conductivity meter at 20°C.

[0076] The washcoat coating can have a viscosity of 0 to 5,000 cPs, e.g., 1 to 3,000 cPs, 2 to 2,000 cPs, 3 to 1,000 cPs, 4 to 500 cPs, or 5 to 300 cPs. In preferred embodiments, the viscosity is 5 to 250 cPs, 10 to 200 cPs, 15 to 180 cPs, 25 to 150 cPs, 50 to 120 cPs, or 60 to 100 cPs. In more preferred embodiments, the washcoat coating has a viscosity of 5 to 200 cPs, even more preferably 25 to 120 cPs, e.g., 50 to 100 cPs.

[0077] Viscosity may be measured at 20° C. on a Brookfield RV DVII+Extra Pro viscometer using an SC4-27 spindle at a spindle speed of 50 rpm.

[0078] The total washcoat coating has a thickness of 0.1 μm to 100 μm, preferably 0.2 μm to 50 μm, 0.5 to 40 μm, 1 μm to 30 μm, 1.5 μm to 20 μm, 2 μm to 10 μm, 3 μm to 8 μm 90 In preferred embodiments, the total washcoat coating may have a d of 0.1 to 10 μm, 0.5 to 9 μm, 1 μm to 8 μm, 1.5 μm to 7.5 μm, 2 μm to 7 μm, 2.5 μm to 6 μm, 3 μm to 5.9 μm. 90 In a more preferred embodiment, the zeolite has a d of 4 to 5.8 μm, e.g., about 5.5 μm. 90 (by volume).

[0079] As used herein, "d 90 The term "(by volume)" refers to the amount of water measured by a Malvern Mastersizer® 3000 equipped with an Aero s dispersion unit available from Malvern Panalytical Ltd (Malvern, UK). 90Refers to measurements (by volume). Dispersion conditions: air pressure = 2 barg, feed rate = 65%, hopper gap = 1.2 mm. Refractive index and absorptivity parameters are set according to the instructions provided in the Malvern Mastersizer® 3000 user manual.

[0080] Coated monolithic article The monolithic article may include multiple different coating layers, which are different from one another. The monolithic article may include two or more layers (e.g., two or more different layers).

[0081] In one embodiment, the monolith article comprises two coatings: one inorganic coating layer (e.g., an inorganic coating layer described herein) and one washcoat coating layer (e.g., a washcoat coating layer described herein). In a preferred embodiment, the inorganic coating layer (e.g., an inorganic coating layer described herein) is coated directly onto the monolith article on the inlet end of the article (i.e., there is no intervening layer between the monolith article and the inorganic oxide coating). In a preferred embodiment, the washcoat coating layer (e.g., a washcoat coating layer described herein) is coated directly onto the monolith article on the outlet end of the article (i.e., there is no intervening layer between the monolith article and the washcoat coating layer).

[0082] FIG. 1 illustrates one embodiment of the present invention. The article is made of multiple channels and has an inlet end (1) and an outlet end (2). An inorganic oxide coating (3) is applied to the inlet end, and a washcoat coating (4) is applied to the outlet end. While the inorganic oxide coating and washcoat coating are shown in FIG. 1 as covering 100% of the length of the article, one skilled in the art will understand that the inorganic coating may be applied to extend from the inlet end for 80-100% of the length of the article (preferably, 90-100%, or about 100% of the length of the article from the inlet end). In an additional or alternative embodiment, the washcoat coating may be applied to extend from the outlet end for 60-100% of the length of the article (preferably, 65-95%, e.g., 70-90% or 75-80% of the length of the article from the outlet end).

[0083] In an alternative embodiment, an inorganic coating layer (e.g., an inorganic coating layer described herein) is coated directly onto the monolith article (i.e., there is no intervening layer between the monolith article and the inorganic oxide coating), and a washcoat coating layer (e.g., a washcoat coating layer described herein) is coated directly onto the inorganic coating layer (i.e., there is no intervening layer between the inorganic coating layer and the washcoat coating layer).

[0084] entrance end The inlet end of the monolith article (eg, the inlet end described herein) comprises (eg, consists of) an inorganic oxide coating.

[0085] In a preferred embodiment, the inorganic oxide coating at the inlet end is coated directly onto the monolith article (ie, there is no intervening layer between the monolith article and the inorganic oxide coating).

[0086] outlet end The outlet end of the monolith article (eg, the outlet end described herein) comprises (eg, consists of) a washcoat coating.

[0087] In a preferred embodiment, the outlet end washcoat coating is coated directly onto the monolith article (ie, there is no intervening layer between the monolith article and the washcoat coating).

[0088] Method for forming a coated monolithic article The present invention also relates to a method of forming a coated monolith article (e.g., a coated monolith article described herein), the method comprising: i) providing a monolithic article having an inlet end and an outlet end; ii) applying an inorganic oxide coating to the inlet end; iii) optionally drying and / or calcining the inorganic coating; iv) applying a washcoat coating to the outlet end; v) optionally drying and / or firing the resulting article.

[0089] An inorganic oxide coating (e.g., the inorganic oxide coating of step ii) is applied to the monolith article. In a preferred embodiment, the inorganic oxide coating is applied in a spraying process. In a particularly preferred embodiment, the inorganic coating is applied only from the inlet end in a spraying process.

[0090] In one embodiment, the inorganic oxide coating is applied in a spraying process, which comprises a first spraying step in which inorganic particles are sprayed as a first dry particle aerosol to form an inorganic particle layer, and then in a second spraying step, a silicone resin is sprayed as a second dry particle aerosol onto the inorganic particle layer.Therefore, the inorganic particles are sprayed before the silicone resin is separately sprayed onto the article coated with the inorganic particles.In a particularly preferred embodiment, the inorganic particles and the silicone resin are applied only from the inlet end in the spraying step.

[0091] Even more preferably, the mixture of inorganic particles and silicone resin is sprayed as a dry particle aerosol to form the inorganic oxide coating layer. Thus, a homogeneous mixture of inorganic particles and silicone resin is applied to provide enhanced adhesion of the inorganic particles to the monolith article upon baking of the silicone resin. In a particularly preferred embodiment, the mixture of inorganic particles and silicone resin is sprayed as a dry particle aerosol from only the inlet end.

[0092] When a mixture of inorganic particles and a silicone resin is sprayed as a dry particle aerosol to form an inorganic oxide coating layer (preferably, the dry particle composition consists of inorganic particles and a 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 10, preferably less than 8, preferably less than 5. For example, this ratio may preferably be about 2 or about 3. Preferably, this ratio is 1 to 4, preferably 2 to 4.5, preferably 2.5 to 4, preferably 2.5 to 3.5, for example, about 3.

[0093] The method can further include calcining the inorganic oxide coating layer before applying the washcoat coating. That is, the method includes calcining a monolithic article having inorganic particles and silicone resin sprayed onto the gas-contacting surfaces of the plurality of channels. Preferably, the calcining step includes heating to a temperature of at least 200°C, preferably at least 300°C, more preferably at least 400°C, and / or to a temperature of up to 600°C, preferably up to 550°C, more preferably up to 530°C. Thus, 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.

[0094] In a preferred embodiment, the inorganic oxide coating layer is dried but not calcined before application of the washcoat coating. The inventors have surprisingly found that it is not essential to calcinate the inorganic oxide coating layer before application of the washcoat coating. This can reduce the amount of energy required to produce the product of the present invention. Therefore, in a preferred embodiment, the inorganic oxide coating layer is not calcined before application of the washcoat coating.

[0095] The inorganic oxide coating layer can be applied so as to extend 80-100% of the length of the substrate from the inlet end. In a preferred embodiment, the inorganic oxide coating layer extends 90-99%, more preferably 95-98%, e.g., about 100%, about 95%, or about 90% of the length of the substrate from the inlet end.

[0096] A washcoat coating (e.g., a washcoat coating described herein, particularly the washcoat coating of step iv)) is applied to the monolith article at the outlet end of the monolith article. The washcoat coating can be applied to the outlet end of the monolith article in a single dose or multiple doses (e.g., two, three, four, or five doses). In a preferred embodiment, the washcoat coating is applied to the monolith article in a single dose or two doses, most preferably a single dose. When multiple doses of washcoat are applied to the monolith article, the same or a different washcoat can be applied each time, and preferably the same washcoat is applied to the monolith article.

[0097] The washcoat coating (e.g., the washcoat coating of step ii) may be applied to extend 60-100% of the length of the article from the exit end. In preferred embodiments, the washcoat coating extends 65-95%, more preferably 70-90%, 75-80%, e.g., about 80%, about 75%, or about 70% of the length of the substrate from the exit end.

[0098] The washcoat coating (e.g., the washcoat coating of step iv)) can be applied using any conventional method, such as an Automated Inversion Depositor (AID) process or a Precision Coating (PC) process. The AID process involves using a piston to force the washcoat into the filter, flipping the part over, and then allowing the washcoat to soak into the walls of the substrate. The PC process involves applying a precise dose using a showerhead, where the washcoat is drawn into the part by gravity and / or vacuum, allowing the washcoat to soak into the walls of the substrate. In a preferred embodiment, the washcoat is applied to the substrate using a PC process. The washcoat coating is performed by dispensing the washcoat through an outlet end and i) applying a vacuum to the washcoat; and / or ii) applying positive pressure to the washcoat; and / or iii) allowing the washcoat to deposit by capillary action; The washcoat can be applied to at least a portion of the channel, allowing the washcoat to coat at least a portion of the channel.

[0099] Preferably, the calcination step comprises heating to a temperature of at least 200°C, preferably at least 300°C, more preferably at least 400°C, and / or to a temperature of up to 600°C, preferably up to 550°C, more preferably up to 530°C. Calcination therefore preferably comprises 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, even more preferably 400°C to 450°C.

[0100] Such temperatures have been found to be optimal for forming an effective binder that imparts its advantageous water resistance to the coated monolith article. Such temperatures are particularly advantageous when the monolith article is a catalytic article, such as a catalytic wall-flow filter, because they allow the silicone resin to be calcined into crosslinked silicon dioxide without adversely affecting catalytic efficiency (i.e., without degrading the catalytic article). Linear siloxanes, such as PDMS, not only do not provide the branching necessary to effectively bind inorganic particles and adhere to the article, but complete decomposition to SiO2 is believed to require temperatures above 550°C, or even above 600°C. Ideally, the calcination temperature is kept as low as possible to reduce the possibility of affecting the catalytic activity of any catalyst present in the monolith article.

[0101] Exhaust gas system and method According to a further aspect, there is provided an exhaust gas system comprising a coated monolith article as described herein or made by a method as described herein, and optionally an internal combustion engine. The internal combustion engine may be a diesel engine, a lean-burn gasoline engine, or an engine powered by liquefied petroleum gas or natural gas. Preferably, the internal combustion engine is a diesel engine. The coated monolith article may be positioned downstream of the engine to treat exhaust gases emitted by the engine.

[0102] According to yet a further aspect of the present invention, there is provided a method for the treatment of an exhaust gas, the method comprising contacting the exhaust gas with a monolith article described herein, or a coated monolith article made by a method described herein.

[0103] Although preferred embodiments of the present invention have been described in detail herein, those skilled in the art will recognize that variations can be made without departing from the scope of the invention or the appended claims.

[0104] The invention will now be further described with reference to the following non-limiting examples and figures.

[0105] As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Use of the term "comprising" is intended to be interpreted as including such features but not excluding other features, and is intended to include options of features necessarily limited to those recited. In other words, unless the context clearly dictates otherwise, this term also includes the limitations "consisting essentially of" (intended to mean that certain additional components may be present provided they do not materially affect the essential properties of the recited feature) and "consisting of" (intended to mean that when components are expressed as percentages by their proportions, these add up to 100%, while accounting for any unavoidable impurities, but that other features may not be included).

[0106] As used herein, the term "g / L" (grams per liter) refers to the mass of the powder divided by the volume of the filter.

[0107] The foregoing detailed description has been provided for purposes of illustration and example, and is not intended to limit the scope of the appended claims. Many variations of the presently preferred embodiments illustrated herein will be apparent to those skilled in the art and remain within the scope of the appended claims and their equivalents. [Example]

[0108] Example 1 Preparation of Comparative Example 1 A monolithic article having an inlet end and an outlet end was prepared. 100% of the washcoat coating was applied through a depositor to the outlet end, and the article was dried in a dynamic drying oven at 115°C and then calcined at 500°C. An inorganic oxide coating layer was applied to the inlet, and the resulting coated article was calcined at 500°C.

[0109] Preparation of Comparative Example 2 A monolithic article having an inlet end and an outlet end was prepared. 50% of the washcoat coating was dispensed through a depositor into the outlet end, the article was dried in a dynamic drying oven at 115°C, and then another 50% of the washcoat coating was dispensed through a depositor into the outlet end. The article was then dried in a dynamic drying oven at 115°C and then calcined at 500°C. An inorganic oxide coating layer was applied to the inlet, and the resulting coated article was calcined at 500°C.

[0110] Preparation of Sample 3 according to the present invention A monolithic article having an inlet end and an outlet end was prepared. An inorganic oxide coating layer was applied to the inlet end, and the article was dried in a dynamic drying oven at 115°C. 50% of the washcoat coating was applied through a depositor from the outlet end, the article was dried in the dynamic drying oven at 115°C, and then another 50% of the washcoat coating was applied through a depositor from the outlet end. The article was then dried in the dynamic drying oven at 115°C and calcined at 500°C.

[0111] Example 2 The filtration efficiency was calculated for Comparative Examples 1 and 2, and Sample 3. The soot was measured before and after the filter on a DPG (diesel particulate generator), and the filtration efficiency was calculated using the following formula: Filtration efficiency = 1-(soot after filter / soot before filter)

[0112] The results are shown in Figure 2.

[0113] FIG. 2 shows that the results of Sample 3 according to the present invention have essentially the same filtration efficiency as Comparative Examples 1 and 2, demonstrating that the present invention exhibits comparable filtration efficiency to Comparative Examples 1 and 2 and can be used as a viable substitute for Comparative Examples 1 and 2.

[0114] Example 3 Mass loading and cold flow back pressure were calculated for Comparative Examples 1 and 2, and Sample 3. Mass loading is measured before and after loading onto the balance. Cold flow back pressure is measured at 600 m 3 The pressure drop is measured in mbar / hour and the results are shown in Figure 3.

[0115] 3 shows that Sample 3 according to the present invention has essentially the same cold stream backpressure as Comparative Examples 1 and 2, demonstrating that the present invention exhibits comparable cold stream backpressures and can be used as a viable replacement for Comparative Examples 1 and 2. Furthermore, essentially the same inorganic coating as Comparative Examples 1 and 2 could be loaded onto Sample 3, resulting in similar catalyst mass loadings for similar cold stream backpressures.

[0116] Example 4 Samples were newly evaluated for filtration efficiency on the engine using a VW RDE Max drive cycle evaluation. Samples were tested after a reference flow through the catalyst. Filtration efficiency is calculated using the following formula:

[0117]

number

[0118] The results are shown in Figure 4. Measurements were performed on particulate matter larger than 10 nm (left) and on particulate matter larger than 23 nm (right).

[0119] FIG. 4 shows that the sample according to the present invention has essentially equivalent filtration efficiency compared to Comparative Examples 1 and 2, demonstrating that the present invention exhibits equivalent filtration efficiency to Comparative Examples 1 and 2 and can be used as a viable substitute for Comparative Examples 1 and 2.

Claims

1. 1. A monolithic article comprising an inlet end and an outlet end and a coating, the coating comprising: a) an inorganic oxide coating applied to the inlet end of the article; b) a washcoat coating applied to said outlet end of said article.

2. The monolithic article of claim 1 , wherein the monolithic article is a monolithic filter, preferably a wall-flow filter, and / or a catalytic article, preferably a catalytic wall-flow filter.

3. the inorganic oxide coating comprises inorganic particles (e.g., inorganic particles comprising an aluminosilicate zeolite) and a silicone resin; Preferably, the inorganic particles comprise an aluminosilicate zeolite selected from the group comprising AEI, BEA, CHA, FAU (e.g., zeolite Y), and MFI; and / or 3. The monolithic article of claim 1 or 2, wherein the total inorganic oxide coating is present at a mass loading of 1 to 25 g / L, such as 2 to 20 g / L, preferably 3 to 15 g / L.

4. 4. The monolithic article of claim 3, wherein the ratio of inorganic particles to silicone resin in the inorganic oxide coating is from 0.5:1 to 5:1, preferably from 1:1 to 4:1, for example, about 2:1 or 3:

1.

5. The washcoat coating comprises ceria zirconia, alumina, a noble metal selected from Pd, Pt, or Rh, barium hydroxide, a rheology modifier, and C ２ ~C ６ 5. The monolith article of any one of claims 1 to 4, comprising an aliphatic amino acid (e.g., 3-amino-propionic acid) and / or having a total washcoat loading of 35 to 150 g / L, preferably 40 to 125 g / L, e.g., 50 to 100 g / L, 60 to 90 g / L, or 65 to 85 g / L.

6. 1. A method of forming a coated monolith article (e.g., the coated monolith article of any one of claims 1-5), the method comprising: i) providing a monolithic article having an inlet end and an outlet end; ii) applying an inorganic oxide coating to said inlet end; iii) optionally drying and / or calcining the inorganic coating; iv) applying a washcoat coating to said outlet end; v) optionally drying and / or firing the resulting article.

7. 7. The method of claim 6, wherein the washcoat coating is applied to extend from 60 to 100% of the length of the article from the outlet end, preferably from 65 to 95%, for example from 70 to 90% or from 75 to 80% of the length of the article from the outlet end.

8. 8. The method of claim 6 or 7, wherein the washcoat loading is applied to the monolith article at the outlet end of the monolith article in a single dose or multiple doses, preferably in a single dose or two doses.

9. The method of any one of claims 6 to 8, wherein the mixture of inorganic particles and silicone resin is sprayed onto the inorganic oxide coating as a dry particle aerosol.

10. 10. The method of any one of claims 6 to 9, wherein the inorganic oxide coating comprises inorganic particles (e.g., inorganic particles comprising an aluminosilicate zeolite) and a silicone resin, preferably wherein the inorganic particles comprise an aluminosilicate zeolite selected from the group comprising AEI, BEA, CHA, FAU (e.g., zeolite Y), and MFI.

11. 11. The method according to any one of claims 6 to 10, wherein the silicone resin has a molecular weight of more than 1,000, preferably more than 2,000, preferably more than 5,000, preferably more than 10,000, and / or a molecular weight of less than 500,000, preferably less than 200,000.

12. The silicone resin has the formula [R ｘ Six ｙ O ｚ ] ｎ wherein R is alkyl or aryl, X is a silicon-bonded functional group, and z is greater than 1 and less than 2, preferably The method of any one of claims 6 to 11, wherein y is less than 1 and / or y is less than x.

13. 13. The method according to any one of claims 6 to 12, wherein the silicone resin has a degree of crosslinking of more than 55%, preferably more than 60%, more preferably more than 65%, and / or a degree of crosslinking of less than 85%, preferably less than 80%.

14. An exhaust gas system comprising a coated monolith article according to any one of claims 1 to 5 or made by the method according to any one of claims 6 to 13, and optionally a combustion engine.

15. 14. A method for the treatment of exhaust gases, the method comprising contacting the exhaust gases with a coated monolith article according to any one of claims 1 to 5 or made by the method according to any one of claims 6 to 13.

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