Processing of particulate filters

Abstract

A method and apparatus for applying a dry powder to a porous substrate (10), a) Position the porous substrate (10) within the holder (2) such that the inlet surface (11) communicates with the inlet chamber (15) and the outlet surface (12) communicates with the vacuum generator, b) Establishing a primary gas flow through the porous substrate (10) using a vacuum generator to apply reduced pressure to the outlet surface (12), c) Spraying the dry powder into or into the inlet chamber (15) such that the dry powder is entrained by the primary gas flow, passes through the inlet surface (11) of the porous substrate (10) and comes into contact with the porous structure (13) of the porous substrate (10), d) Directing the secondary gas flow to be on and / or across the inlet surface of the porous substrate (10) during the spraying of the dry powder, e) Using the pressure and / or flow rate of the secondary gas flow to control the axial distribution of the dry powder deposited on the porous structure (13) of the porous substrate (10), Methods and apparatus including

Description

[Technical Field]

[0001] This disclosure relates to a method and apparatus for coating a dry powder onto a porous substrate. In some embodiments, the present invention relates to an improvement of a method and apparatus for coating a filter having 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. The filter may be a wall-flow filter. [Background technology]

[0002] European Patent Application Publication No. 4013954(A1) describes a method and apparatus for processing a filter for filtering particulate matter from exhaust gas, the method comprising: a) a step of containing dry powder in a reservoir; b) a step of placing a filter in a filter holder, the filter comprising a porous substrate having an inlet surface and an outlet surface, the inlet surface and the outlet surface separated by a porous structure; c) a step of establishing a primary gas flow through the porous structure of the filter by applying a reduced pressure to the outlet surface of the filter; d) a step of transferring the dry powder from the reservoir to a spraying device located upstream of the inlet surface of the filter; and e) a step of spraying the dry powder toward the inlet surface of the filter using a spraying device such that the dry powder is carried by the primary gas flow, passes through the inlet surface of the filter, and comes into contact with the porous structure.

[0003] Although this method and apparatus have proven effective for packing dry powder into porous structures, optimizing the packing of dry powder into such porous structures remains necessary. For example, the amount and location of dry powder within the porous structure can affect back pressure, the location of soot during operation, and potentially the filtration efficiency of the porous substrate. [Overview of the project]

[0004] In a first aspect, the present disclosure is a method for coating a dry powder onto a porous substrate, wherein the porous substrate has an inlet surface at an inlet end and an outlet surface at an outlet end, and the inlet surface and the outlet surface are separated by a porous structure, and the method is a) A step of positioning a porous substrate within a holder such that the inlet surface communicates with the inlet chamber and the outlet surface communicates with the vacuum generator, b) A step of establishing a primary gas flow through the porous substrate from the inlet surface to the outlet surface by applying a reduced pressure to the outlet surface of the porous substrate using a vacuum generator, c) A step of spraying dry powder into or into the inlet chamber such that the dry powder is entrained by the primary gas flow, passes through the inlet surface of the porous substrate, and comes into contact with the porous structure, d) A step of directing a secondary gas flow onto and / or across the inlet surface of a porous substrate while spraying dry powder, e) A step of controlling the axial distribution of dry powder deposited within the porous structure of a porous substrate using the pressure and / or flow rate of a secondary gas flow, The present invention provides a method that includes [a specific method].

[0005] Controlling the axial distribution of dry powder is -In order to deflect the axial distribution of the dry powder deposited within the porous structure toward the inlet end of the porous substrate, a secondary gas flow with relatively high pressure and / or flow rate is selected, - In order to deflect the axial distribution of the dry powder deposited within the porous structure toward the outlet end of the porous substrate, select a secondary gas flow with relatively low pressure and / or flow rate, or stop the operation of the secondary gas flow. -In order to obtain the intermediate axial distribution of the dry powder deposited within the porous structure, a secondary gas flow with relatively intermediate pressure and / or flow rate is selected, It may include.

[0006] While not bound by theory, it is thought that the momentum of dry powder particles imparted by the primary gas flow (and potentially by the spraying means) tends to preferentially transport the dry powder toward the outlet end of the porous substrate. The secondary gas flow is thought to create a localized turbulent zone on or above the inlet surface that imparts a lateral component to the momentum, which has the effect of reducing this momentum and / or deflecting the axial distribution of the dry powder that accumulates toward the inlet end of the porous substrate.

[0007] Advantageously, this method allows for direct and repeatable control of the axial deposition of the dry powder. In this way, back pressure, the position of soot during operation, and, in some cases, the filtration efficiency of porous substrates can be more controllable than with conventional solutions.

[0008] The secondary gas flow is For the entire duration of spraying the dry powder, or Part of the period of spraying dry powder It may operate over a period of time.

[0009] The duration and timing of the secondary gas flow can be used to fine-tune the position of the dry powder deposition.

[0010] The secondary gas flow may remain active to blow away any dry powder accumulated on the inlet surface of the porous substrate, or it may be activated after the spraying of the dry powder has stopped. The vacuum generator may remain active while the secondary gas flow is operating after the spraying of the dry powder has stopped, so that the dry powder blown away from the inlet surface is carried by the primary gas flow and passes through the inlet surface of the porous substrate.

[0011] Advantageously, the use of a secondary gas stream provides a practical, easy-to-operate, and low-maintenance means of cleaning the inlet surface of porous substrates. The secondary gas stream requires no power during operation and does not cause any obstruction to the gas stream as it approaches the inlet surface. Beneficially, by keeping the vacuum generator operational during the operation of the secondary gas stream, the utilization of dry powder is increased as the dry powder enters the porous structure through the inlet surface. Beneficially, the secondary gas stream from the same source can be used to both control the location of dry powder deposition within the porous substrate and to clean the inlet surface.

[0012] The secondary gas flow may be configured to be a 360° or substantially 360° gas flow.

[0013] The secondary gas flow may be configured to be directed at a downward angle above the inlet surface.

[0014] The method may further include using a ring airblade to generate a secondary gas flow. The ring airblade may be oriented to direct the gas flow at a downward angle over the inlet surface of a porous substrate. For example, the ring airblade may have a molded outlet that uses the Coanda effect to deflect radially inward gas flow downward, generating a conical gas flow that can be directed toward the inlet surface. The ring airblade may discharge a gas flow of 360° or substantially 360°. In some embodiments, the ring airblade may comprise two semicircular elements, each supplied by a gas inlet. When the two elements are joined, a complete ring surrounding the inlet surface may be formed. When two elements are used, the presence of end walls may mean that the outlet opening does not extend completely over 360°. However, it will be understood that the discharged gas flow still extends substantially over 360°.

[0015] A source of secondary gas flow, for example a ring air blade, may be located within the inlet chamber or between the inlet chamber and the inlet face of the porous substrate, or may be arranged in series between a portion of the inlet chamber. In some embodiments, the source may have a smaller outer diameter than the inlet chamber and be located concentrically within the inlet chamber. In other embodiments, the source may have an outer diameter size similar to that of the inlet chamber, and may be stacked in series between the inlet chamber and the inlet face of the porous substrate.

[0016] The inlet chamber may for example optionally be a tube having an open upper end. The lower end of the tube may be in fluid communication with the inlet face of the porous substrate.

[0017] The secondary gas flow may be supplied at a pressure of up to 8 bar, optionally 1 to 8 bar, optionally 1 to 6 bar, optionally 1, 2, 3, 4, 5, 6, 7, or 8 bar.

[0018] A source of secondary gas flow, for example a ring air blade, may discharge gas at a flow rate of up to 150 liters per minute, optionally up to 200 liters per minute, optionally up to 250 liters per minute.

[0019] The dry powder may be sprayed into or within the inlet chamber using a spraying device, optionally a spray nozzle. The spray nozzle may use a gas flow to entrain the dry powder during spraying. For example, the spraying device may comprise a compressed air gun. A non-limiting example of a suitable compressed air gun is the STAR Professional gravity feed spray gun 1.4mm, part number STA 2591100C.

[0020] When the pressure and / or flow rate of the secondary gas flow is used to control the axial distribution of the dry powder, the spatial separation of the spraying device, e.g., the spray nozzle, from the inlet face may remain fixed. Advantageously, the method enables the use of a fixed spraying device, e.g., a fixed spray nozzle, while at the same time allowing the position of the dry powder deposition to be varied. This avoids the time delays and costs required to modify the apparatus to change the position of the spraying device when changing the size or type of porous substrate to be treated.

[0021] The spraying device may be positioned at a distance of 100 cm or more from the inlet face, optionally 150 cm or more, optionally 200 cm or more from the inlet face. Advantageously, positioning the spraying device at such a distance enables coating of the dry powder onto a porous substrate having a relatively large diameter inlet face, which is not possible when the spraying device is positioned too close to the inlet face. According to the method, a relatively large spacing of the spraying device from the inlet face, which may result in a relatively high momentum of the dry powder particles, can be adapted by controlling the pressure and / or flow rate of the secondary gas flow such that the axial distribution of the deposited dry powder can still be deflected towards the inlet end.

[0022] The gas flow generated by the vacuum generator may be a flow of air or other suitable gas. The secondary gas flow may be a pressurized flow of air or other suitable gas.

[0023] This method may further include continuously coating a dry powder onto multiple porous substrates, wherein for each of the multiple porous substrates, the pressure and / or flow rate of the secondary gas flow is selected to control the axial distribution of the dry powder deposited within the porous structure of the porous substrate. Advantageously, by selecting an appropriate pressure and / or flow rate for the secondary gas flow, multiple porous substrates (which may be of different types and sizes) can be easily adapted. In particular, it may be possible to process different porous substrates without the need to individualize the primary gas flow for each porous substrate or to spatially separate the spraying device from the inlet surface. This can result in simpler and faster processing cycles.

[0024] The spatial separation between the spray nozzle for spraying the dry powder and the inlet surfaces of the multiple porous substrates may remain fixed.

[0025] In a second aspect, the present disclosure relates to an apparatus for coating a dry powder onto a porous substrate, wherein the porous substrate has an inlet surface at an inlet end and an outlet surface at an outlet end, and the inlet surface and the outlet surface are separated by a porous structure, and the apparatus is a) A holder for holding a porous substrate, b) An inlet chamber communicating with the inlet surface, c) A vacuum generator communicating with the outlet surface to establish a primary gas flow through a porous substrate from the inlet surface to the outlet surface, d) A spraying device for spraying dry powder into or inside the inlet chamber, e) A secondary gas source for establishing a secondary gas flow onto and / or across the inlet surface of a porous substrate, f) A controller for selecting the pressure and / or flow rate of the secondary gas flow to control the axial distribution of dry powder deposited within the porous structure of the porous substrate, To provide an apparatus that includes the following features.

[0026] As described above, the secondary gas source may be oriented to direct the gas flow at a downward angle onto the inlet surface of the porous substrate. The secondary gas source may be configured to discharge a 360° or substantially 360° gas flow. The secondary gas source may be a ring air blade. The gas outlet plane of the ring air blade may be positioned 1 to 10 cm above the plane of the inlet surface. The ring air blade may be located inside the inlet chamber or between the inlet chamber and the inlet surface of the porous substrate.

[0027] 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 that all water molecules are completely absent. Dry powder is preferably free-flowing.

[0028] In some embodiments, the dry powder may contain or consist of a silicone resin. The silicone resins are known and include branched cage oligosiloxanes and polysiloxanes. The branching in the silicone resin arises from the presence of so-called "T" and / or "Q" units in the resin, referring to RSiO3 and SiO4 units, respectively (where R is an alkyl or aryl group), with further silicon units bonded to oxygen atoms. "M" units, i.e., R3SiO units, are terminal units where the oxygen atom provides bonding to the resin backbone. Similarly, "D" units, i.e., R2SiO2 units, provide linear bonding across two oxygen atoms. One well-known unbranched and linear polysiloxane is polydimethylsiloxane (PDMS, i.e., (Me2SiO) n )

[0029] Preferably, the silicone resin is solid at room temperature (e.g., about 25°C). Therefore, the silicone resin preferably has a melting point above 25°C, preferably above 30°C, and more preferably above 35°C. Preferably, the melting point of the silicone resin is less than 100°C, preferably below 95°C, below 90°C, below 85°C, or below 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. International Publication WO2011 / 151711 discloses the bonding of powders in place by treatment with polydimethylsiloxane, which forms silica when hydrolyzed at a sufficiently high temperature.

[0030] Similarly, silicone resins have a glass transition temperature (T) above 30°C, preferably above 35°C, and / or below 100°C, preferably below 80°C. g It may be preferable to have a melting point and / or glass transition temperature. Although not bound by theory, silicone resins having such a melting point and / or glass transition temperature are particularly suitable for powder coating processes, i.e., for effectively dispersing fine particles throughout a porous substrate, but low enough to allow for low temperatures or firing, thereby effectively and efficiently adhering inorganic particles to the gas-contacting surface of the channel walls of the porous substrate.

[0031] 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 less than 500,000, preferably less than 200,000.

[0032] As used herein, molecular weight is the weight-average molecular weight (M) which can be measured using any conventional means in the art. Wrefers to). In some embodiments, the hydrogen bonding provided by the hydroxy functional groups provides a silicone resin having a sufficiently high melting point and / or glass transition temperature, so the molecular weight can be relatively low. Accordingly, in some embodiments, the molecular weight of the silicone resin can be 1,000 to 10,000, preferably 1,000 to 5,000, more preferably 1,200 to 3,500, for example 1,500 to 2,000. Silicone resins having a molecular weight of less than 1,000 are typically liquid, and are less preferred because they are either not suitable for dry spraying, or do not have as many branches as larger molecules that are believed to provide enhanced binding of inorganic particles to a porous substrate.

[0033] Nevertheless, the molecular weight of the silicone resin can preferably be 15,000 to 150,000, preferably 20,000 to 120,000, more preferably 60,000 to 100,000. Some preferred resins have an Mw of 8,000 to 15,000, some have an Mw of 20,000 to 60,000, and others have an Mw of 80,000 to 120,000.

[0034] It is particularly preferred that the silicone resin has the formula [R x SiX y O z n , wherein R is an alkyl group or an 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 enough to provide the required oligomers or polymers for the silicone resin, particularly a resin that is solid at room temperature. Depending on the molecular weight of the R groups and X groups, when n is greater than 10, an M W greater than 1,000 can be achieved, when n is greater than 100, an M W greater than 10,000 can be achieved, and when n is greater than 1,000, an M W greater than 100,000 can be achieved. Accordingly, n can preferably be greater than 10, greater than 100, or greater than 1,000.

[0035] ​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. When z=2, x and y are 0, thus giving silica (i.e., silicon dioxide, (SiO₂ n ), therefore z is less than 2. Similarly, when z=1, x+y=2, thus providing a linear resin (e.g., -O-(SiRX)-O-(SiRX)-O-), which is a substituted polysiloxane composed of "D" units (e.g., (RXSiO n ), therefore z is greater than 1. An example is polydimethylsiloxane. Accordingly, O refers to oxygen that crosslinks two silicon atoms in the polymer backbone of the silicone resin.

[0036] Preferably, 0<x+y<2, more preferably 0<x+y≦1.5, further preferably 0<x+y≦1. Preferably, x, y and / or x+y is greater than 0.1, more preferably greater than 0.2. In one preferred embodiment, x+y is 1, which provides 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, more preferably 5y≦x, further preferably 10y≦x. In one embodiment, y is 0. For example, when polysilsesquioxane is polymethylsilsesquioxane (MeSiO 3 / 2 ) n or other polyalkylsilsesquioxanes, y is 0.

[0037] Typically, if present, X is one or more of H, hydroxy(OH), Cl, and C1-C6 alkoxys, preferably OH and one or more of C1-C6 alkoxys, and preferably the C1-C6 alkoxys are selected from methoxy(OCH3) and ethoxy(OCH2CH3). In a particularly preferred embodiment, X is one or both of OH and ethoxy. However, X may be a reactive functional group such as aminyl(NH2,NR2), epoxy, acrylate, and vinyl, but these are less preferred because the presence of a hydroxyl group or an alkoxy group is considered to provide more effective crosslinking during calcination. As described above, any oxygen present in the terminal functional group refers to the silicon-bridged oxygen atom in the above formula. z It does not contribute to ".

[0038] In some embodiments, the dry powder may contain or consist of zeolite. The zeolite is a structure formed from alumina and silica, and SAR determines the reaction sites within the zeolite structure. The zeolite may be a small-pore zeolite (e.g., a zeolite with a maximum ring size of 8 tetrahedral atoms), a medium-pore zeolite (e.g., a zeolite with a maximum ring size of 10 tetrahedral atoms), or a large-pore zeolite (e.g., a zeolite with a maximum ring size of 12 tetrahedral atoms), or a combination of two or more of these.

[0039] Suitable examples of zeolites include silicate zeolites, aluminosilicate zeolites, metal-substituted aluminosilicate zeolites, AlPO, MeAlPO, SAPO, and MeAPSO. In some embodiments, the zeolite is selected from aluminosilicate, borosilicate, gallosilicate, SAPO, AlPO, MeAPSO, and MeAPSO zeolites.

[0040] If the zeolite is a microporous zeolite, it may have a skeletal structure represented by a Framework Type Code (FTC) selected from the group including ACO, AEI, AEN, AFN, AFT, AFX, ANA, APC, APD, ATT, CDO, CHA, DDR, DFT, EAB, EDI, EPI, ERI, GIS, GOO, IHW, ITE, ITW, LEV, LTA, KFI, MER, MON, NSI, OWE, PAU, PHI, RHO, RTH, SAT, SAV, SFW, SIV, THO, TSC, UEI, UFI, VNI, YUG, and ZON, or mixtures and / or combinations and / or intergrowths of two or more of these (for example, consisting of...). In some embodiments, the microporous zeolite has a skeletal structure selected from the group including CHA, LEV, AEI, AFX, ERI, LTA, SFW, KFI, DDR, and ITE (for example). In some embodiments, the microporous zeolite has a skeletal structure selected from the group including CHA and AEI (for example). The microporous zeolite may have a CHA skeletal structure.

[0041] If the zeolite is a medium-pore zeolite, it may have a skeletal structure represented by a skeletal type code (FTC) selected from the group including AEL, AFO, AHT, BOF, BOZ, CGF, CGS, CHI, DAC, EUO, FER, HEU, IMF, ITH, ITR, JRY, JSR, JST, LAU, LOV, MEL, MFI, MFS, MRE, MTT, MVY, MWW, NAB, NAT, NES, OBW, PAR, PCR, PON, PUN, RRO, RSN, SFF, SFG, STF, STI, STT, STW, SVR, SZR, TER, TON, TUN, UOS, VSV, WEI, and WEN, or mixtures of two or more of these and / or intergrowth (e.g., consisting of ). In some embodiments, the medium-pore zeolite has a skeletal structure selected from the group including FER, MEL, MFI, and STT (e.g., consisting of ). In some embodiments, the medium-pore zeolite has a skeletal structure selected from the group including FER and MFI (e.g., consisting of ), particularly MFI. When the medium-pore molecular sieve has an FER or MFI skeleton, the zeolite may be ferrielite, silicalite, or ZSM-5.

[0042] If the zeolite is a large-pore zeolite, it may have a skeletal structure represented by a skeletal type code (FTC) selected from the group including AFI, AFR, AFS, AFY, ASV, ATO, ATS, BEA, BEC, BOG, BPH, BSV, CAN, CON, CZP, DFO, EMT, EON, EZT, FAU, GME, GON, IFR, ISV, ITG, IWR, IWS, IWV, IWW, JSR, LTF, LTL, MAZ, MEI, MOR, MOZ, MSE, MTW, NPO, OFF, OKO, OSI, RON, RWY, SAF, SAO, SBE, SBS, SBT, SEW, SFE, SFO, SFS, SFV, SOF, SOS, STO, SSF, SSY, USI, UWY, and VET, or mixtures of two or more of these and / or intergrowth (for example, consisting of...). In some embodiments, the large-pore zeolite has a skeletal structure selected from the group including AFI, BEA, MAZ, MOR, and OFF (for example, consisting of ). In some embodiments, the large-pore zeolite has a skeletal structure selected from the group including BEA, MOR, and FAU (for example, consisting of ). When the large-pore molecule has a skeletal structure of FTC, BEA, FAU, or MOR, the zeolite may be beta-zeolite, faujasite, zeolite Y, zeolite X, or mordenite.

[0043] The following are ABW, ACO, AEI, AEL, AEN, AET, AFG, AFI, AFN, A FO, AFR, AFS, AFT, AFX, AFY, AHT, ANA, APC, APD, AST, ASV, ATN, ATO, AT S, 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、EAB、EDI、EEI、EMT、EON、EPI、ERI、ESV、ETR、EUO、FAU、FER、FRA、G IS, GIU, GME, GON, GOO, HEU, IFR, IFY, IHW, IRN, ISV, ITE, ITH, ITW, IW R, 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、NAB、NAT、NES、NON、NPO、NPT、NSI、OBW、OFF、OSI、OSO、OWE、P AR, PAU, PHI, PON, RHO, RON, RRO, RSN, RTE, RTH, RUT, RWR, RWY, SAO, SA S, 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, Z ON, this is a smooth and smooth process. 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 wide range.

[0044] In another embodiment, the inorganic particles are refractory oxide particles that can be based on oxides selected from the group consisting of alumina, silica, zirconia, ceria, chromia, magnesia, calcia, titania, and any two or more mixed oxides 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) can be produced by an exothermic process, such as flame decomposition.

[0045] In some embodiments, the dry powder may contain or consist of a metal compound for forming a metal oxide by thermal decomposition. The dry powder may consist of a single metal compound, or a mixture, blend, or continuous dosing of two or more metal compounds. The metal compound, or each metal compound, may contain one or more metal cations. If multiple metal cations are present, they may be the same metal or different metals. The metal compound may contain or consist of a metal hydroxide, metal phosphate, metal carbonate, metal sulfate, metal perchlorate, metal iodide, metal oxalate, metal acetate, metal chlorate, or a mixture thereof. The metal in the metal compound may contain or consist of one or more of magnesium, calcium, strontium, barium, aluminum, zirconium, manganese, lithium, iron, cobalt, nickel, copper, or gallium. The dry powder may further contain a metal oxide or a mixture of metal oxides. Optionally, the dry powder may contain 90% by weight or more of a metal compound for forming a metal oxide by thermal decomposition and 10% by weight or less of a metal oxide or mixed metal oxide. Optionally, the dry powder may contain 95% by weight or more of a metal compound for forming a metal oxide by thermal decomposition and 5% by weight or less of a metal oxide or mixed metal oxide. Optionally, the dry powder may contain 99% by weight or more of a metal compound for forming a metal oxide by thermal decomposition and 1% by weight or less of a metal oxide or mixed metal oxide. The metal in the metal oxide or mixed metal oxide may contain or consist of one or more of aluminum, magnesium, calcium, strontium, barium, aluminum, zirconium, manganese, lithium, iron, cobalt, nickel, copper, or gallium. Optionally, the dry powder may contain or consist of a metal hydroxide, metal phosphate, metal carbonate, or a mixture thereof. The metal hydroxide may be selected from the group consisting of magnesium hydroxide, calcium hydroxide, strontium hydroxide, and barium hydroxide. Metallic phosphates may be selected from the group consisting of magnesium phosphate, calcium phosphate, strontium phosphate, and barium phosphate.The metal carbonate may be selected from the group consisting of magnesium carbonate, calcium carbonate, strontium carbonate, and barium carbonate.

[0046] The dry powder may consist of a single powder type or a mixture of powder types. For example, the dry powder may contain, or consist of, a mixture of zeolite and silicone resin.

[0047] The porous substrate may be, for example, a through-flow monolith or a filter. In this specification, the term “filter” refers to a porous substrate having a porous structure suitable for filtering particulate matter from exhaust gases. The porous substrate may be formed from, for example, sintered metal, ceramic, or metal fibers. The filter may be a wall-flow type filter made from a porous material, such as ceramic, in the form of a monolithic array of numerous small channels extending along the length of the body. For example, the filter may be formed from cordierite, various forms of silicon carbide, or aluminum titanate.

[0048] The filter may be a "bare" filter, or alternatively, it may have incorporated catalytic functionality such as oxidation, NOx trapping, or selective catalytic reduction activity. The porous substrate may include a composition (known as a washcoat) that coats the porous structure of the filter. The washcoat may be a catalytic washcoat. The catalytic washcoat may include a catalyst selected from the group consisting of hydrocarbon traps, three-way catalysts (TWCs), NOx absorbents, oxidation catalysts, selective catalytic reduction (SCR) catalysts, lean NOx catalysts, and any combination of two or more thereof. The catalysts, e.g., TWCs, NOx absorbents, oxidation catalysts, hydrocarbon traps, and lean NOx catalysts, may contain one or more platinum group metals, particularly selected from the group consisting of platinum, palladium, and rhodium.

[0049] The filters may include, for example, diesel exhaust particulate filters (DPFs), catalytic soot filters (CSFs), selective catalytic reduction filters (SCRFs), lean NOx trap filters (LNTFs), gasoline particulate filters (GPFs), ammonia slip catalyst filters (ASCFs), or combinations of two or more of these (for example, filters comprising a selective catalytic reduction (SCR) catalyst and an ammonia slip catalyst (ASC)).

[0050] The shape and dimensions of a filter, such as channel wall thickness and its porosity, may vary depending on the intended use of the filter. A filter may be configured for use with an internal combustion engine to filter exhaust gases emitted by the engine. The internal combustion engine may be a gasoline spark-ignition engine. However, when configured for use with internal combustion engines in the form of diesel or gasoline engines, the filter finds specific applications.

[0051] In this specification, the terms “inlet” and “outlet” refer to the orientation of the porous substrate when exposed to the primary gas flow generated by a vacuum generator, with the gas flow from the inlet surface or inlet end to the outlet surface or outlet end. It will be understood that the porous substrate may adopt other orientations in subsequent processing steps or uses, for example, when used in a vehicle to treat exhaust gases. For example, the exhaust gas flow through the porous substrate during use may be from the “inlet” to the “outlet” or vice versa.

[0052] In this specification, the term “vacuum generator” refers to a device or combination of devices that functions to generate a reduced pressure. Non-limiting examples of suitable devices include vacuum generators operating on the Venturi principle, vacuum pumps such as rotary-blade and liquid-filled vacuum pumps, and vortex blowers.

[0053] In this specification, the term “controller” may refer to a function that may include hardware and / or software. A controller may comprise a control unit or a computer program running on dedicated or shared computing resources. A controller may comprise a single unit or consist of multiple operablely connected subunits. A controller may reside on a single processing resource or be distributed across spatially separated processing resources. A controller may include a microcontroller, one or more processors (such as one or more microprocessors), memory, configurable logic, firmware, and the like. [Brief explanation of the drawing]

[0054] From here on, aspects and embodiments of this disclosure will be described simply as examples with reference to the attached drawings. [Figure 1] This is a schematic diagram of the apparatus according to this disclosure. [Figure 2] This is a schematic view from above of the ring air blade and the inlet surface of the porous substrate of the apparatus shown in Figure 1. [Figure 3] Figure 2 is a schematic side view of the ring airblade and porous substrate. [Figure 4] This graph shows the relative mass of deposited dry powder as a function of distance from the inlet surface for an exemplary porous substrate. [Figure 5] This graph shows the powder deposition ratio against secondary gas flow pressure. [Figure 6] This is a photograph of the entrance surface of a porous substrate after spraying it with dried powder. [Figure 7]Figure 6 is a photograph of the porous substrate after operation of the ring air blade. [Modes for carrying out the invention]

[0055] Those skilled in the art will recognize that one or more features of one aspect or embodiment of the present disclosure may be combined with one or more features of any other aspect or embodiment of the present disclosure, unless the immediate context teaches otherwise.

[0056] Next, an example of the apparatus according to this disclosure will be described with reference to Figure 1, which shows a schematic diagram of an apparatus 1 for processing a porous substrate 10 for filtering particulate matter from exhaust gas. The porous substrate 10 is of a type having an inlet surface 11 and an outlet surface 12, and the inlet surface 11 and the outlet surface 12 are separated by a porous structure 13.

[0057] The apparatus 1 comprises a holder 2 for holding a porous substrate 10, an inlet chamber 15 communicating with an inlet surface 11, a vacuum generator communicating with the outlet surface 12 for establishing a primary gas flow through the porous substrate 10 from the inlet surface 11 to the outlet surface 12, a spraying device for spraying dry powder into or into the inlet chamber 15, and a secondary gas supply source for generating a secondary gas flow, shown as an example in the form of a ring air blade 30.

[0058] The holder 2 may be provided with means for securely holding the porous substrate 10. The holder 2 may include an inflatable upper collar 3 supplied by an expansion line 5 and an inflatable lower collar 4 supplied by an expansion line 6.

[0059] The vacuum generator may include a vacuum cone 17 connected via line 16 to, for example, a regenerative blower.

[0060] The spraying device may include a spray nozzle 20 to which dry powder is supplied along a powder supply line 21, for example by gravity. A gas supply line 22 can supply compressed gas, such as compressed air, to the spray nozzle 20 to carry and move the dry powder and spray it out of the spray nozzle 20. The spray nozzle 20 may be located inside the inlet chamber 15, as shown in Figure 1, or it may be located outside the inlet chamber 15 but directed to spray the dry powder into the inlet chamber 15.

[0061] The spraying device may be located at a distance h of 100 cm or more from the inlet surface 11, optionally at a distance of 150 cm or more, or optionally at a distance of 200 cm or more. The distance h may be fixed for a specific device 1.

[0062] The inlet chamber 15 may optionally include a tube 15 having an open upper end. The tube 15 may have a shape that conforms to the shape of the inlet surface 11 and a size equal to or larger than the inlet surface 11.

[0063] The secondary gas supply source, for example, the ring air blade 30, may be located inside the inlet chamber 15, or in series with one or more parts of the inlet chamber 15, or between the inlet chamber 15 and the inlet surface 11, as shown in Figure 1. The gas supply unit 31 supplies pressurized gas, for example, air, to the ring air blade 30.

[0064] A controller may be provided for selecting the pressure and / or flow rate of the secondary gas flow generated by the secondary gas source. For example, the controller may be electronic and / or software controlled and operably connected to a valve and / or pump. Alternatively, the controller may be a manual control for setting the pressure and / or flow rate of the secondary gas flow, for example, by manually adjusting valve or pump settings, thereby controlling the pressure and / or flow rate of the secondary gas flow released by the ring air blade 30.

[0065] As shown in Figures 2 and 3, the ring air blade 30 may comprise two semicircular elements 32, 33 that together form a ring shape extending 360° around the inlet surface 11 of the porous substrate 10. Each semicircular element 32, 33 may have its own gas inlets 31a, 31b that can be supplied from a common gas supply unit 31.

[0066] The ring air blade 30 may have gas outlets 35 that extend around the inner circumferential walls of each semicircular element 32, 33 and are directed substantially radially inward, as shown in Figure 3. Thus, as indicated by the arrows in Figure 2, the gas that enters each semicircular element 32, 33 is guided around that element 32, 33 and exits substantially radially so that the gas is released around all or substantially all of the 360° of the ring air blade 30.

[0067] The lower surface 36 of the gas outlet 35 may be rounded, as shown in Figure 3, so as to deflect the gas exiting the gas outlet 35 downward toward the inlet surface 11 due to the Coanda effect. Therefore, a substantially conical airflow can be obtained.

[0068] The plane of the gas outlet 35 of the ring air blade 30 may be positioned 1 to 10 cm above the plane of the inlet surface 11, as schematically shown in Figure 3 using reference numeral d.

[0069] When in use, the porous substrate 10 is initially positioned within the holder 2 such that its inlet surface 11 communicates with the inlet chamber 15 and its outlet surface 12 communicates with a vacuum generator, such as a vacuum cone 17. The upper and lower inflatable collars 3 and 4 can be inflated to secure the porous substrate 10.

[0070] Next, by applying reduced pressure to the outlet surface 12 of the porous substrate 10 using a vacuum generator, a primary gas flow is established through the porous substrate 10 from the inlet surface 11 to the outlet surface 12.

[0071] Furthermore, the ring air blade 30 operates to generate a secondary gas flow downward on the inlet surface 11 at a secondary gas flow pressure and / or flow rate set to a desired level.

[0072] The pressure and / or flow rate of the secondary gas flow may remain constant throughout the processing of the particular porous substrate 10, or it may change during the processing of the particular porous substrate 10.

[0073] The dry powder is carried along by the primary gas flow, passes through the turbulent zone generated by the secondary gas flow along the inlet chamber 15, and is then sprayed into or into the inlet chamber 15, for example, using a spray nozzle 20, so that it passes through the inlet surface 11 of the porous substrate 10 and comes into contact with the porous structure.

[0074] The secondary gas flow may be active for the entire duration of the dry powder spraying, or for part of the duration of the dry powder spraying.

[0075] In the above example, the secondary airflow is described as being generated by the ring air blade 30, but it is within the scope of this disclosure to use alternative arrangements to generate the secondary airflow on or across the inlet surface 11 and to generate a turbulent zone on or above the inlet surface 11. [Examples]

[0076] Figure 4 shows a graph plotting the relative mass of the deposited dry powder against the distance from the inlet surface for a porous substrate sample.

[0077] The porous substrate was an aluminum titanate filter substrate supplied by Corning. Diameter = 171.9 mm, length = 152.4 mm.

[0078] A washcoat was applied to the filter substrate. The washcoat contained a 9:1 ratio of Cu-exchanged zeolite (CHA, SAR=18.5, supplied by Tosoh, Cu content=3.3 wt%) suspended in water and stabilized gamma alumina (supplied by PIDC). The washcoat had a d90 of 4-5 μm. The surface of the zeolite was modified using aminosilane (see U.S. Patent No. 11192793(B2)).

[0079] The application of the wash coat was carried out in accordance with European Patent No. 3122458. The wash coat was applied to the outlet end of the filter substrate, coating 80% of the filter volume, with a fill amount of 1.58 g / in of the filter volume. -3 An additional wash coat was applied to the inlet end of the filter substrate, coating 35% of the filter volume, and the baking filling amount was 0.52 g / in of the filter volume. -3 The filter substrate was baked at 500°C for 1 hour.

[0080] The dry powder was a mixture of zeolite (chabasite zeolite with 4 μm d90 and 23 SAR, available from Tosoh) and Silres MK powder (methyl silicone resin with 9 μm d90, available from Wacker), prepared in a zeolite:silicone resin ratio of 3:1. The resulting mixed powder was sprayed onto a wash-coated filter substrate from the inlet end under a constant airflow. The airflow forming the primary gas flow was 300 m 3 It was [time]. Next, the coated portion was baked at 500°C for 1 hour.

[0081] The particle size measurements required to obtain the d90 of solid particles (e.g., zeolite or Silres MK powder) can be obtained by laser diffraction particle size analysis using a Malvern Mastersizer 3000, a volume-based method (i.e., d90 can also be referred to as d(v,0.90)), and the particle size distribution is determined by applying a mathematical Mie theory model. The laser diffraction system works by determining the particle diameter based on the spherical approximation. For particle size measurements by laser diffraction particle size analysis, diluted samples were prepared by sonication in surfactant-free distilled water at 35 watts for 30 seconds.

[0082] A ring air blade 30 was used as the source of the secondary gas flow. The spray nozzle height h was fixed at 200 cm throughout. Samples of the filter substrate were treated with the secondary gas flow turned off (marked "none" in Figure 4), as well as with secondary gas flows at pressures of 2 bar, 3.5 bar, and 5 bar (for clarity, the 3.5 bar result is omitted from Figure 4).

[0083] Figure 4 is a graph showing the relative mass of the deposited dry powder as a function of distance from the inlet surface of the filter substrate. The results were obtained by X-ray scanning the filter substrate before and after coating with the dry powder. In each scan, the radially averaged X-ray absorption was measured every 0.5 mm along the axis of the filter substrate. The pre-coating measurement was then subtracted from the post-coating measurement, and the results were then normalized.

[0084] As can be seen in Figure 4, when the secondary gas flow is turned off, the accumulation of dry powder is deflected towards the outlet end of the filter substrate, with a peak approximately 120 cm from the inlet surface. When the secondary gas flow was set to 2 bar, under otherwise the same processing conditions, an intermediate distribution of dry powder was obtained along the length of the filter structure. When the secondary gas flow was set to 5 bar, under otherwise the same processing conditions, an accumulation of dry powder occurred that was deflected towards the inlet end of the filter substrate, with a peak approximately 5 cm from the inlet surface and a secondary peak approximately 55 cm from the inlet surface.

[0085] Figure 5 shows graphs of the powder deposition ratio against secondary gas flow pressure for filter substrates tested as described above at secondary gas flow pressures of 0, 2, 3.5, and 5 bar. The powder deposition ratio was calculated by dividing the normalized absorption value at 60 mm from the inlet surface by the normalized absorption value at 120 mm from the inlet surface.

[0086] As can be seen in Figure 5, a strong linear relationship is observed between the secondary gas flow pressure and the powder deposition ratio, demonstrating that the use of secondary gas flow pressure provides a reliable and controllable means for controlling the deposition location of dry powder within a porous substrate.

[0087] As shown in Figure 6, when the porous substrate 10 is treated with dry powder, dry powder may accumulate on the inlet surface 11, particularly on the ends of the walls separating the inlet channels and / or on any channel where the inlet end is blocked.

[0088] Therefore, the ring air blade 30 can be operated to direct a gas flow downward onto the inlet surface 11 of the porous substrate 10 in order to blow away any dry powder accumulated on the inlet surface 11. The vacuum generator may remain activated while the ring air blade 30 is operating so that the dry powder blown off from the inlet surface 11 is carried by the gas flow and passes through the inlet surface 11 of the porous substrate 10.

[0089] As shown in Figure 7, this effectively cleans away the accumulation of dry powder from the inlet surface 11.

[0090] The ring air blade 30 may be operated to blow away dry powder after the spraying of dry powder into or into the inlet chamber 15 has stopped (but while the vacuum generator is still operating). Additionally or alternatively, the ring air blade 30 can be operated while the dry powder is being sprayed into or into the inlet chamber 15.

Claims

1. A method for coating a dry powder onto a porous substrate, wherein the porous substrate has an inlet surface at an inlet end and an outlet surface at an outlet end, and the inlet surface and the outlet surface are separated by a porous structure, and the method is a) The step of positioning the porous substrate within the holder such that the inlet surface communicates with the inlet chamber and the outlet surface communicates with the vacuum generator, b) The step of establishing a primary gas flow through the porous substrate from the inlet surface toward the outlet surface by applying a reduced pressure to the outlet surface of the porous substrate using the vacuum generator, c) A step of spraying the dry powder into or into the inlet chamber such that the dry powder is carried by the primary gas flow, passes through the inlet surface of the porous substrate, and comes into contact with the porous structure, d) A step of directing a secondary gas flow onto and / or across the inlet surface of the porous substrate while spraying the dry powder, e) Using the pressure and / or flow rate of the secondary gas flow to control the axial distribution of the dry powder deposited within the porous structure of the porous substrate, Methods that include...

2. Controlling the axial distribution of the dried powder is - Selecting a secondary gas flow with relatively high pressure and / or flow rate in order to deflect the axial distribution of the dry powder deposited within the porous structure toward the inlet end of the porous substrate, - In order to deflect the axial distribution of the dry powder deposited within the porous structure toward the outlet end of the porous substrate, select a secondary gas flow with a relatively low pressure and / or flow rate, or stop the operation of the secondary gas flow. - In order to obtain the intermediate axial distribution of the dry powder deposited within the porous structure, a secondary gas flow with a relatively intermediate pressure and / or flow rate is selected, The method according to claim 1, including the method described in claim 1.

3. The aforementioned secondary gas flow For the entire duration of the spraying of the dry powder, or Part of the spraying period of the aforementioned dried powder The method according to claim 1 or 2, which operates over a period of time.

4. The method according to any one of claims 1 to 3, wherein the secondary gas flow is maintained in operation or operates after the spraying of the dry powder has stopped in order to blow away the dry powder accumulated on the inlet surface of the porous substrate.

5. The method according to claim 4, wherein the vacuum generator maintains an operating state during the operation of the secondary gas flow after the spraying of the dry powder has stopped, such that the dry powder blown out from the inlet surface is carried along with the primary gas flow and passes through the inlet surface of the porous substrate.

6. The method according to any one of claims 1 to 5, wherein the secondary gas flow is configured to be a 360° or substantially 360° gas flow.

7. The method according to any one of claims 1 to 6, wherein the secondary gas flow is configured to be directed at a downward angle onto the inlet surface.

8. The method according to any one of claims 1 to 7, further comprising using a ring air blade to generate the secondary gas flow.

9. The method according to any one of claims 1 to 8, wherein the dry powder is sprayed into or into the inlet chamber using a spray nozzle, and the axial distribution of the dry powder is controlled using the pressure and / or flow rate of the secondary gas flow, while the spatial separation of the spray nozzle from the inlet surface remains fixed.

10. The method according to any one of claims 1 to 9, further comprising continuously coating a plurality of porous substrates with a dry powder, wherein for each of the plurality of porous substrates, the pressure and / or flow rate of the secondary gas flow is selected to control the axial distribution of the dry powder deposited within the porous structure of the porous substrate.

11. The method according to claim 10, wherein the spatial separation between the spray nozzle for spraying the dry powder and the inlet surfaces of the plurality of porous substrates remains fixed.

12. An apparatus for coating a dry powder onto a porous substrate, wherein the porous substrate has an inlet surface at the inlet end and an outlet surface at the outlet end, and the inlet surface and the outlet surface are separated by a porous structure, and the apparatus is a) A holder for holding the porous substrate, b) An inlet chamber communicating with the inlet surface, c) A vacuum generator communicating with the outlet surface to establish a primary gas flow through the porous substrate from the inlet surface toward the outlet surface, d) A spraying device for spraying the dried powder into or inside the inlet chamber, e) A secondary gas supply source for establishing a secondary gas flow onto and / or across the inlet surface of the porous substrate, f) A controller for selecting the pressure and / or flow rate of the secondary gas flow to control the axial distribution of the dry powder deposited within the porous structure of the porous substrate, A device equipped with the following features.

13. The apparatus according to claim 12, wherein the secondary gas supply source is oriented so as to direct the gas flow at a downward angle onto the inlet surface of the porous substrate.

14. The apparatus according to claim 12 or 13, wherein the secondary gas supply source is configured to discharge a gas flow of 360° or substantially 360°.

15. The apparatus according to any one of claims 12 to 14, wherein the secondary gas supply source is a ring air blade.

16. The apparatus according to claim 15, wherein the plane of the gas outlet of the ring air blade is positioned 1 to 10 cm above the plane of the inlet surface.

17. The apparatus according to claim 15 or claim 16, wherein the ring air blade is located inside the inlet chamber or between the inlet chamber and the inlet surface of the porous substrate.

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