Treatment of particle filters

Abstract

A method and apparatus for applying dry powder to a porous substrate (10), the method comprising: a) positioning the porous substrate (10) in a holder (2) such that an inlet face (11) is in communication with an inlet chamber (15) and an outlet face (12) is in communication with a vacuum generator; b) applying reduced pressure to the outlet face (12) using a vacuum generator, establishing a primary gas flow through the porous substrate (10); c) spraying dry powder into or within the inlet chamber (15) such that the dry powder is entrained in the main gas stream and passes through the inlet face (11) of the porous substrate (10) to contact the porous structure (13) of the porous substrate (10); d) during spraying of the dry powder, directing a secondary gas stream onto and / or across the inlet face of the porous substrate (10); and e) using the pressure and / or flow rate of the secondary gas stream to control the axial distribution of the dry powder deposited in the porous structure (13) of the porous substrate (10).

Description

[0001] This disclosure relates to methods and apparatus for applying dry powder to a porous substrate. In some embodiments, the invention relates to improvements in methods and apparatus for coating filters, the filters comprising a porous substrate having an inlet face and an outlet face, wherein the inlet face is separated from the outlet face by a porous structure. The filter may be a wall-flow filter. Background Technology

[0002] EP 4013954 A1 describes a method and apparatus for treating a filter used to filter particulate matter from exhaust gas, the method comprising the steps of: a) containing dry powder in a reservoir; b) positioning a filter in a filter holder, the filter comprising a porous substrate having an inlet face and an outlet face separated by a porous structure; c) establishing a main gas flow through the porous structure of the filter by applying a pressure reduction to the outlet face of the filter; d) transferring the dry powder from the reservoir to a spraying device located upstream of the inlet face of the filter; and e) spraying the dry powder toward the inlet face of the filter using the spraying device such that the dry powder is entrained in the main gas flow and passes through the inlet face of the filter to contact the porous structure.

[0003] While the method and apparatus have proven effective in loading dry powder into porous structures, optimization of the loading process is still needed. For example, the amount and location of the dry powder within the porous structure can affect back pressure, soot location during operation, and in some cases, the filtration efficiency of the porous substrate. Summary of the Invention

[0004] In a first aspect, this disclosure provides a method for applying dry powder to a porous substrate having an inlet face at an inlet end and an outlet face at an outlet end, wherein the inlet face and the outlet face are separated by a porous structure, the method comprising the following steps:

[0005] a) Position the porous substrate in the retainer such that the inlet surface is in communication with the inlet chamber and the outlet surface is in communication with the vacuum generator;

[0006] b) By using a vacuum generator to apply pressure to the outlet surface of the porous substrate, a main gas flow is established from the inlet surface to the outlet surface through the porous substrate;

[0007] c) Spraying dry powder into the inlet chamber or spraying dry powder into the inlet chamber, so that the dry powder is entrained in the main gas flow and passes through the inlet surface of the porous substrate to contact the porous structure.

[0008] d) During dry powder coating, the secondary gas flow is directed to and / or across the inlet face of the porous substrate; and

[0009] e) Use the pressure and / or flow rate of the secondary gas stream to control the axial distribution of dry powder deposited in the porous structure of the porous substrate.

[0010] Controlling the axial distribution of the dry powder may include:

[0011] - Select a relatively high pressure and / or flow rate of the secondary gas flow to deflect the axial distribution of the dry powder deposited in the porous structure toward the inlet end of the porous substrate.

[0012] - Select a relatively low pressure and / or flow rate of the secondary gas flow or disable the secondary gas flow to deflect the axial distribution of the dry powder deposited in the porous structure toward the outlet end of the porous substrate; and

[0013] - Select a relatively intermediate pressure and / or flow rate for the secondary gas flow to obtain an intermediate axial distribution of the dry powder deposited in the porous structure.

[0014] Without being bound by theory, it is believed that the momentum imparted to the dry powder particles by the main gas flow (and potentially by means of spraying) tends to preferentially carry the dry powder toward the outlet end of the porous substrate. It is believed that the secondary gas flow generates a localized turbulence zone at or above the inlet face, which reduces the momentum and / or imparts a lateral component to the momentum, having the effect of deflecting the axial distribution of the dry powder deposited toward the inlet end of the porous substrate.

[0015] Advantageously, this method allows for simple and repeatable control of the axial deposition of the dry powder. In this way, back pressure, soot location during operation, and in some cases the filtration efficiency of the porous substrate can be more controllable compared to prior art solutions.

[0016] The secondary gas flow can be active for the following:

[0017] The entire duration of dry powder spraying; or

[0018] Part of the duration of dry powder coating.

[0019] The duration and timing of this activation of the secondary gas flow can be used to fine-tune the deposition location of the dry powder.

[0020] After the spraying of the dry powder has stopped, the secondary gas flow may remain active or be activated to blow away the dry powder accumulated on the inlet surface of the porous substrate. After the spraying of the dry powder has stopped, the vacuum generator may remain active during the activation of the secondary gas flow, such that the dry powder blown away from the inlet surface is entrained in the main gas flow and passes through the inlet surface of the porous substrate.

[0021] Advantageously, the use of the secondary gas flow provides a practical, easy-to-operate, and low-maintenance means for cleaning the inlet face of the porous substrate. The secondary gas flow may not require any electricity during use and does not obstruct the gas flow when it approaches the inlet face. Advantageously, keeping the vacuum generator active during the operation of the secondary gas flow increases the utilization rate of the dry powder by allowing it to enter the porous structure through the inlet face. Advantageously, the same source of the secondary gas flow can be used to control the deposition location of the dry powder within the porous substrate and for cleaning the inlet face.

[0022] The secondary gas flow can be configured as a 360° or substantially 360° gas flow.

[0023] The secondary gas flow can be configured to be directed onto the inlet surface at a downward angle.

[0024] The method may also include using an annular air vane to generate the secondary gas flow. The annular air vane may be oriented to guide the gas flow at a downward angle to the inlet face of the porous substrate. For example, the annular air vane may include a shaped outlet that uses the Coanda effect to deflect the radially inward gas flow downward to generate a tapered gas flow that can be guided toward the inlet face. The annular air vane may emit a gas flow of 360° or substantially 360°. In some embodiments, the annular air vane may include two semi-circular elements, each supplied from a gas inlet. When these two elements are combined, a complete ring surrounding the inlet face can be formed. With two elements, the outlet opening may not extend a full 360° due to the presence of end walls. However, it will be understood that the emitted gas flow will still extend around approximately 360°.

[0025] The source of the secondary gas flow (e.g., the annular air blade) may be located within the inlet chamber or between the inlet chamber and the inlet face of the porous substrate, or arranged in series between portions of the inlet chamber. In some embodiments, the outer diameter of the source may be smaller than that of the inlet chamber and concentrically located within the inlet chamber. In other embodiments, the source may have an outer diameter 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.

[0026] The inlet chamber may be, for example, a tube, optionally having an open upper end. The lower end of the tube may be in fluid communication with the inlet surface of the porous substrate.

[0027] The secondary gas flow can be supplied at pressures up to 8 bar, optionally at pressures from 1 bar to 8 bar, optionally at pressures from 1 bar to 6 bar, optionally at pressures of 1 bar, 2 bar, 3 bar, 4 bar, 5 bar, 6 bar, 7 bar, or 8 bar.

[0028] The source of this secondary gas flow (e.g., the annular air blade) can emit 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.

[0029] The dry powder can be sprayed into the inlet chamber using a spraying device, or optionally using a nozzle, or sprayed into the inlet chamber. The nozzle can use a gas flow to entrain the dry powder during spraying. For example, the spraying device includes 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 STA2591100C.

[0030] When the pressure and / or flow rate of the secondary gas stream are used to control the axial distribution of the dry powder, the spatial distance between the spraying device (e.g., nozzle) and the inlet face can remain constant. Advantageously, this method allows for the use of a fixed spraying device (e.g., a fixed nozzle) while permitting variation in the deposition location of the dry powder. This avoids the time delays and costs associated with modifying the equipment to change the position of the spraying device when the size or type of the porous substrate being treated is changed.

[0031] The spraying device can be located at a distance of 100 cm or more, optionally 150 cm or more, or optionally 200 cm or more from the inlet surface. Advantageously, positioning the spraying device at such a distance allows the dry powder to be coated onto a porous substrate with a relatively large diameter inlet surface, which would be impossible if the spraying device were positioned too close to the inlet surface. According to this method, the relatively large distance between the spraying device and the inlet surface (which may result in relatively high momentum of the dry powder particles) can be accommodated by controlling the pressure and / or flow rate of the secondary gas flow, so as to still allow for an axially skewed distribution of the deposited dry powder at the inlet end.

[0032] The gas stream generated by the vacuum generator can be an air stream or other suitable gas stream. The secondary gas stream can be a pressurized air stream or other suitable gas.

[0033] The method may further include continuously applying dry powder to a plurality of porous substrates, 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 in the porous structure of the porous substrate. Advantageously, the plurality of porous substrates (which may have different types and sizes) can be accommodated simply by selecting appropriate pressure and / or flow rate of the secondary gas flow. In particular, different porous substrates can be processed without having to individualize the main gas flow or without the spatial separation between the spraying device and the inlet face of each porous substrate. This results in simpler and faster processing cycles.

[0034] The spatial distance between the nozzle used for spraying the dry powder and the inlet surface of the plurality of porous substrates can be kept fixed.

[0035] In a second aspect, this disclosure provides an apparatus for applying dry powder to a porous substrate having an inlet face at an inlet end and an outlet face at an outlet end, wherein the inlet face and the outlet face are separated by a porous structure, the apparatus comprising:

[0036] a) A retainer for holding a porous substrate;

[0037] b) An entrance chamber that is connected to the entrance facade;

[0038] c) A vacuum generator connected to the outlet surface and used to establish a main gas flow from the inlet surface to the outlet surface through the porous substrate;

[0039] d) A spraying apparatus for spraying dry powder into or within the inlet chamber; and

[0040] e) A secondary gas source for establishing a secondary gas flow at and / or across the inlet face of the porous substrate; and

[0041] f) A controller for selecting the pressure and / or flow rate of the secondary gas stream to control the axial distribution of dry powder deposited in the porous structure of the porous substrate.

[0042] As indicated above, the secondary gas source can be oriented to guide the gas flow at a downward angle to the inlet surface of the porous substrate. The secondary gas source can be configured to emit a gas flow of 360° or substantially 360°. The second gas source can be an annular air vane. The plane of the gas outlet of the annular air vane can be positioned between 1 cm and 10 cm above the plane of the inlet surface. The annular air vane can be located within the inlet chamber or between the inlet chamber and the inlet surface of the porous substrate.

[0043] In this specification, the term "dry powder" refers to a particulate composition that is not suspended or dissolved in a liquid. This does not necessarily mean the complete absence of all water molecules. The dry powder is preferably free-flowing.

[0044] In some embodiments, the dry powder may contain or be composed of silicone resin. Silicone resins are known and are branched cage-like oligomeric siloxanes and polysiloxanes. The branching in silicone resins is due to the presence of so-called "T" and / or "Q" units in the resin, which refer to RSiO3 and SiO4 units respectively (R being an alkyl or aryl group), where additional silicon units are bonded to oxygen atoms. "M" units (i.e., R3SiO units) are terminal units where oxygen atoms provide a connection to the resin backbone. Similarly, "D" units (i.e., R2SiO2 units) provide a linear connection across two oxygen atoms. A well-known unbranched and linear polysiloxane is polydimethylsiloxane (PDMS; i.e., (Me2SiO)). n ).

[0045] Preferably, the silicone resin is solid at room temperature (e.g., about 25°C). Therefore, the silicone resin preferably has a melting point greater than 25°C, more preferably greater than 30°C, and more preferably greater than 35°C. Preferably, the silicone resin has a melting point less than 100°C, more 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. WO2011 / 151711 discloses treating a powder bonded at the appropriate location with a polydimethylsiloxane, which hydrolyzes at a sufficiently high temperature to form silica.

[0046] Similarly, it is preferable that the silicone resin has a glass transition temperature (T0) greater than 30°C, preferably greater than 35°C, and / or less than 100°C, preferably less than 80°C. g Without being bound by theory, silicone resins believed to have such melting points and / or glass transition temperatures are particularly suitable for powder coating processes, i.e., for effective particle dispersion across porous substrates, but with melting points and / or glass transition temperatures low enough to allow for low-temperature calcination, thereby effectively and efficiently adhering inorganic particles to the gas contact surfaces of the channel walls of porous substrates.

[0047] Preferably, the silicone resin has a molecular weight greater than 1,000, preferably greater than 2,000, preferably greater than 5,000, preferably greater than 10,000, and / or less than 500,000, preferably less than 200,000.

[0048] As used in this article, molecular weight refers to weight-average molecular weight (M). WThe molecular weight can be measured using any conventional component in the art. In some embodiments, the molecular weight may be relatively low because the hydrogen bonding provided by the hydroxyl functional groups gives the silicone resin 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, such as 1,500 to 2,000. Silicone resins with a molecular weight below 1,000 are less preferred because these silicone resins are typically liquid and not suitable for dry spraying, or do not have as much branching as larger molecules, which are believed to enhance the bonding of inorganic particles to porous substrates.

[0049] However, the molecular weight of the silicone resin can preferably be from 15,000 to 150,000, preferably from 20,000 to 120,000, and preferably from 60,000 to 100,000. Some preferred resins have an M value of 8,000 to 15,000. w Some resins have a value of 20,000 to 60,000, while others have a value of 80,000 to 120,000.

[0050] Particularly preferred is that the organosilicon resin has the formula [R] x SiX y O z ] n Where R is an alkyl or aryl group, X is a functional group bonded to silicon, and z is greater than 1 and less than 2. As will be understood, n is large in order to provide the desired oligomers or polymers of silicone resins, particularly resins that are solid at room temperature. Although depending on the molecular weight of the R and X groups, when n is greater than 10, M > 1,000 can be obtained. W When n is greater than 100, an M greater than 10,000 can be obtained. W Furthermore, when n is greater than 1,000, an M greater than 100,000 can be obtained. W Therefore, n can preferably be greater than 10, greater than 100, or greater than 1,000.

[0051] As will be understood, R is an alkyl or aryl group bonded to silicon, and X is a non-hydrocarbon functional group bonded to silicon. Similarly, since silicon is a tetravalent atom, it should be understood that x + y + 2z = 4. z is less than 2 because where z = 2, x and y = 0, providing silicon dioxide (i.e., silicon dioxide; (SiO2)). n Similarly, z is greater than 1 because where z=1 and x+y=2, we obtain substituted polysiloxanes (e.g., (RXSiO) composed of "D" units. n), a linear resin (e.g., –O–(SiRX)–O–(SiRX)–O–) is obtained. An example is polydimethylsiloxane. Thus, O refers to the oxygen that bridges two silicon atoms in the polymer backbone of the silicone resin.

[0052] Preferably, 0 < x + y < 2, preferably 0 < x + y ≤ 1.5, preferably 0 < x + y ≤ 1. Preferably, x, y, and / or x + y are greater than 0.1, preferably greater than 0.2. In a preferred embodiment, x + y is 1, resulting in a silicone resin commonly referred to as polysilsesquioxane. Preferably, y is less than 1 and / or y is less than x. Even more preferably, 2y ≤ x, preferably 5y ≤ x, preferably 10y ≤ x. In one embodiment, y is 0. For example, y is 0, where the polysilsesquioxane is polyalkylsilsesquioxane, such as polymethylsilsesquioxane (MeSiO 3 / 2 ) n .

[0053] Generally, when present, X is one or more of H, hydroxyl (OH), Cl, and C1–C6 alkoxy groups, preferably one or more of OH and C1–C6 alkoxy groups, preferably where the C1–C6 alkoxy group is selected from methoxy (OCH3) and ethoxy (OCH2CH3). In a particularly preferred embodiment, X is one or both of OH and ethoxy. However, X is a functional group, which can also be a reactive functional group, such as an amino group (NH2, NR2), epoxy group, acrylate group, and vinyl group, but these functional groups are less preferred because the presence of hydroxyl groups or alkoxy groups is considered to provide more effective crosslinking during calcination. As described above, any oxygen present in the terminal functional group does not contribute to the "O z " in the above formula, and this "O z " refers to the silicon-bridged oxygen atom.

[0054] In some embodiments, the dry powder may contain zeolite or consist of zeolite. Zeolite is a structure formed by alumina and silica, and the SAR determines the reactive sites within the zeolite structure. Zeolite can be a small-pore zeolite (e.g., zeolite with a maximum ring size of eight tetrahedral atoms), a mesopore zeolite (e.g., zeolite with a maximum ring size of ten tetrahedral atoms), or a large-pore zeolite (e.g., zeolite with a maximum ring size of twelve tetrahedral atoms) or a combination of two or more of them.

[0055] Examples of suitable zeolites include silicate zeolites, aluminosilicate zeolites, metal-substituted aluminosilicate zeolites, AlPO, MeAlPO, SAPO, MeAPSO, etc. In some embodiments, the zeolite is selected from aluminosilicate zeolites, borosilicate zeolites, gallosilicate zeolites, SAPO zeolites, AlPO zeolites, MeAPSO zeolites, and MeAPO zeolites.

[0056] When the zeolite is a microporous zeolite, it may have a skeletal structure represented by a skeletal type code (FTC) selected from the group consisting of: 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 commensal forms of two or more of these. In some embodiments, the microporous zeolite has a skeletal structure selected from the group consisting of: CHA, LEV, AEI, AFX, ERI, LTA, SFW, KFI, DDR, and ITE. In some embodiments, the pore zeolite has a framework structure selected from the group consisting of (e.g., composed of) the following: CHA and AEI. The pore zeolite may have a CHA framework structure.

[0057] In the case of mesoporous zeolite, the mesoporous zeolite may have a skeletal structure represented by a skeletal type code (FTC) selected from the group consisting of (e.g., composed of) the following: 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 a mixture of two or more of them and / or commensal organisms. In some embodiments, the mesoporous zeolite has a framework structure selected from the group consisting of (e.g., composed of) FER, MEL, MFI, and STT. In some embodiments, the mesoporous zeolite has a framework structure selected from the group consisting of (e.g., composed of) FER and MFI, specifically MFI. When the mesoporous molecular sieve has an FER or MFI framework, the zeolite can be magnesium alkali zeolite, silica rock, or ZSM-5.

[0058] In the case of macroporous zeolite, macroporous zeolite may have a skeletal structure represented by a skeletal type code (FTC) selected from the group consisting of (e.g., composed of) the following: 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 and / or commensal forms of two or more of these. In some embodiments, the macroporous zeolite has a framework structure selected from the group consisting of (e.g., composed of) the following: AFI, BEA, MAZ, MOR, and OFF. In some embodiments, the macroporous zeolite has a framework structure selected from the group consisting of (e.g., composed of) the following: BEA, MOR, and FAU. When the macroporous molecules have a framework structure of FTC BEA, FAU, or MOR, the zeolite can be a β-zeolite, octahedral zeolite, Y-type zeolite, X-type zeolite, or mordenite.

[0059] In some embodiments, the zeolite has a framework type selected from the following: ABW, ACO, AEI, AEL, AEN, AET, AFG, AFI, AFN, AFO, AFR, AFS, AFT, AFX, AFY, AHT, ANA, APC, APD, AST, ASV, ATN, ATO, ATS, ATT, ATV, AVL, AWO, AWW, BCT, BEA, BEC, BIK, BOG, BPH, BRE, CAN, CAS, SCO. 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, GIS, GIU, GME, GON, GOO, HEU, IFR, IFY, IHW, IRN, ISV, ITE, ITH, ITW, IWR, IWW, JBW, KFI, LA U, LEV, LIO, LIT, LOS, LOV, LTA, LTL, LTN, MAR, MAZ, MEI, MEL, MEP, MER, MFI, MFS, MON, MOR, MOZ, MSO, MTF, MTN, M TT, MTW, MWF, MWW, NAB, NAT, NES, NON, NPO, NPT, NSI, OBW, OFF, OSI, OSO, OWE, PAR, PAU, PHI, PON, RHO, RON, RRO, RSN, RTE, RTH, RUT, RWR, RWY, SAO, SAS, SAT, SAV, SBE, SBS, SBT, SFE, SFF, SFG, SFH, SFN, SFO, SFW, SGT, SOD, SOS , SSY, STF, STI, STT, TER, THO, TON, TSC, UEI, UFI, UOZ, USI, UTL, VET, WI, VNI, VSV, WIE, WEN, YUG, ZON, or their combination. In some implementations, the zeolite has a framework type selected from the following: AEI, AFT, AFV, AFX, AVL, BEA, CHA, DDR, EAB, EEI, ERI, FAU, FER, IFY, IRN, KFI, LEV, LTA, LTN, MER, MOR, MWF, MFI, NPT, PAU, RHO, RIE, RTH, SAS, SAT, SAV, SFW, TSC, and UFI.

[0060] In another embodiment, the inorganic particles are refractory oxide particles, which may be based on oxides selected from the group consisting of: alumina, silica, zirconium oxide, cerium dioxide, chromium oxide, magnesium oxide, calcium oxide, titanium dioxide, and any two or more mixed oxides thereof. Preferably, the refractory oxide particles include calcium aluminate, pyrolytic alumina, pyrolytic silica, pyrolytic titanium dioxide, pyrolytic zirconium oxide, pyrolytic cerium dioxide, alumina aerogel, silica aerogel, titanium dioxide aerogel, zirconium oxide aerogel, cerium dioxide aerogel, or mixtures thereof. The one or more refractory powders (refractory oxide particles) can be produced by a pyrochemical process, such as flame pyrolysis.

[0061] In some embodiments, the dry powder may contain or consist of a metal compound for forming a metal oxide through thermal decomposition. The dry powder may consist of a single metal compound, or may consist of a mixture or blend, or a continuous dose of two or more metal compounds. The metal compound, or each metal compound, may contain one or more metal cations. In the presence of multiple metal cations, these metal compounds may use the same or different metals. The metal compound may contain or consist of: metal hydroxides, metal phosphates, metal carbonates, metal sulfates, metal perchlorates, metal iodides, metal oxalates, metal acetates, metal chlorates, or mixtures thereof. The metal of 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 also contain metal oxides or mixed metal oxides. Optionally, the dry powder contains 90% by weight or more of a metal compound for forming a metal oxide through thermal decomposition, and 10% by weight or less of a metal oxide or mixed metal oxide. Optionally, the dry powder contains 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 contains 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 include or consist of one or more of the following: aluminum, magnesium, calcium, strontium, barium, aluminum, zirconium, manganese, lithium, iron, cobalt, nickel, copper, or gallium. Optionally, the dry powder contains or consists of the following: metal hydroxides, metal phosphates, metal carbonates, or mixtures thereof. Metal hydroxides may be selected from the group consisting of: magnesium hydroxide, calcium hydroxide, strontium hydroxide, and barium hydroxide. Metal phosphates may be selected from the group consisting of: magnesium phosphate, calcium phosphate, strontium phosphate, and barium phosphate. Metal carbonates may be selected from the group consisting of: magnesium carbonate, calcium carbonate, strontium carbonate, and barium carbonate.

[0062] Dry powder can consist of a single powder type or a mixture of powder types. For example, dry powder may contain or consist of a mixture of zeolite and silicone resin.

[0063] The porous substrate can be, for example, a flow-through monolithic material 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 can be formed, for example, from sintered metal, ceramic, or metal fibers. Filters can be of the wall-flow type made of porous materials (e.g., ceramics), manufactured as a monolithic array of numerous small channels extending along the length of the substrate. For example, filters can be formed from cordierite, various forms of silicon carbide, or aluminum titanate.

[0064] The filter can be a "bare" filter or alternatively a filter with incorporated catalytic capabilities, such as oxidation, NOx capture, or selective catalytic reduction activity. The porous substrate can include a composition of porous structures coated on the filter (referred to as a support coating). The support coating can be a catalytic support coating. The catalytic support coating can include catalysts selected from the group consisting of: hydrocarbon traps, three-way catalysts (TWCs), NOx absorbers, oxidation catalysts, selective catalytic reduction (SCR) catalysts, lean NOx catalysts, and any combination of two or more of these. The catalyst (e.g., TWCs, NOx absorbers, oxidation catalysts, hydrocarbon traps, and lean NOx catalysts) may contain one or more platinum group metals, particularly those selected from the group consisting of platinum, palladium, and rhodium.

[0065] The filter may be, for example, a diesel particulate filter (DPF), a catalytic soot filter (CSF), a selective catalytic reduction filter (SCRF), a lean NOx trap filter (LNTF), a gasoline particulate filter (GPF), an ammonia leak catalyst filter (ASCF), or a combination of two or more of these (e.g., a filter that includes a selective catalytic reduction (SCR) catalyst and an ammonia leak catalyst (ASC).

[0066] The shape and dimensions of a filter (e.g., characteristics such as channel wall thickness and porosity) can vary depending on the intended application of the filter. A filter can be configured for use with an internal combustion engine to filter exhaust gases emitted by that engine. The internal combustion engine can be a gasoline spark-ignition engine. However, when configured for use with an internal combustion engine in the form of a diesel or gasoline engine, the filter has a specific application.

[0067] In this specification, the terms "inlet" and "outlet" refer to the orientation of the porous substrate when subjected to a main gas flow generated by a vacuum generator, wherein the gas flow is from the inlet face or inlet end toward the outlet face or outlet end. It should be understood that the porous substrate may employ other orientations in subsequent processing steps or applications, such as when used in vehicles 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.

[0068] In this specification, the term "vacuum generator" refers to a device or combination of devices used to generate a reduced pressure. Non-limiting examples of suitable devices include vacuum generators operating according to the Venturi principle, vacuum pumps such as rotary vane and liquid ring vacuum pumps, and regenerative blowers.

[0069] In this specification, the term "controller" can refer to a function that may include hardware and / or software. A controller may include a control unit or a computer program that runs on dedicated or shared computing resources. A controller may include a single unit or may consist of multiple subunits operatively connected. A controller may reside on a single processing resource or may 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, etc. Attached Figure Description

[0070] Aspects and embodiments of this disclosure will now be described by way of example only with reference to the accompanying drawings, in which:

[0071] Figure 1 This is a schematic diagram of the device according to this disclosure;

[0072] Figure 2 yes Figure 1 A schematic diagram of the annular air blades and the inlet surface of the porous substrate of the device;

[0073] Figure 3 From Figure 2 A schematic diagram of the side of the annular air blade and the porous substrate;

[0074] Figure 4 This is a graph showing the relative mass of dry powder deposited on an example porous substrate relative to the distance from the inlet surface;

[0075] Figure 5 It is a graph showing the powder deposition ratio relative to the secondary gas flow pressure;

[0076] Figure 6 This is a photograph of the inlet surface of the porous substrate after the dry powder coating has been applied; and

[0077] Figure 7 After the operation of the annular air blades Figure 6 Photographs of porous substrates. Detailed Implementation

[0078] Readers in the art will recognize that, unless the present context otherwise teaches, one or more features of one aspect or embodiment of this disclosure may be combined with one or more features of any other aspect or embodiment of this disclosure.

[0079] Now refer to Figure 1 The illustration describes an example of an apparatus according to the present disclosure, showing 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 the type having an inlet surface 11 and an outlet surface 12, which are separated by a porous structure 13.

[0080] Device 1 includes: a retainer 2 for holding a porous substrate 10; an inlet chamber 15 communicating with an inlet surface 11; a vacuum generator communicating with an outlet surface 12 and for establishing a main gas flow from the inlet surface 11 to the outlet surface 12 through the porous substrate 10; a spraying device for spraying dry powder into or within the inlet chamber 15; and a secondary gas source for generating a secondary gas flow, exemplified by an annular air blade 30.

[0081] The retainer 2 may include components for securely holding the porous substrate 10. The retainer 2 may include an upper inflatable collar 3 supplied by an inflation line 5 and a lower inflatable collar 4 supplied by an inflation line 6.

[0082] The vacuum generator may include a vacuum cone 17 connected via a line 16 to, for example, a regenerative blower.

[0083] The spraying apparatus may include a nozzle 20, which supplies dry powder, for example, by gravity supply along a powder supply line 21. A gas feed line 22 may supply compressed gas (e.g., compressed air) to the nozzle 20 for entraining, moving, and expelling the dry powder from the nozzle 20. The nozzle 20 may be as follows: Figure 1 The powder is located inside the entrance chamber 15, or alternatively outside the entrance chamber 15, but is oriented to spray dry powder into the entrance chamber 15.

[0084] The spraying device can be located at a distance h from the inlet surface of 11,100 cm or more, optionally at a distance of 150 cm or more, optionally at a distance of 200 cm or more. The distance h can be fixed for a specific device 1.

[0085] The entrance chamber 15 may include a pipe 15, which optionally has an open upper end. The pipe 15 may have a shape conforming to the shape of the entrance surface 11 and a size equal to or greater than that of the entrance surface 11.

[0086] The secondary gas source (e.g., annular air blade 30) can be as follows: Figure 1 The annular air vane 30 is located within the inlet chamber 15, or may be arranged in series with one or more portions of the inlet chamber 15, or is located between the inlet chamber 15 and the inlet surface 11. The gas supply source 31 supplies pressurized gas (e.g., air) to the annular air vane 30.

[0087] A controller may be provided for selecting the pressure and / or flow rate of the secondary gas stream generated by the secondary gas source. For example, the controller may be an electronic and / or software control operatively 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 stream, for example, by manually adjusting valve or pump settings, thereby controlling the pressure and / or flow rate of the secondary gas stream (e.g., a gas stream emitted by the annular air vane 30).

[0088] like Figure 2 and Figure 3 As shown, the annular air blade 30 may include two semi-circular elements 32 and 33, which together form an annulus extending 360° around the inlet surface 11 of the porous substrate 10. Each semi-circular element 32 and 33 may have its own gas inlet 31a and 31b, which can be supplied from a common gas supply source 31.

[0089] The annular air blade 30 may have a gas outlet 35 that extends around the inner peripheral wall of each semicircular element 32, 33 and is as follows: Figure 3 As shown, it is oriented approximately radially inward. Therefore, as... Figure 2 As indicated by the arrows, the gas entering each semicircular element 32, 33 is guided around its element 32, 33 and exits approximately radially, such that the gas is emitted around all or substantially all 360° of the annular air blade 30.

[0090] The lower surface 36 of the gas outlet 35 can be circular so that, due to the Coanda effect, the gas leaving the gas outlet 35 is deflected downwards toward the inlet surface 11, such as... Figure 3 As shown. Therefore, a roughly conical airflow can be obtained.

[0091] The plane of the gas outlet 35 of the annular air blade 30 can be positioned between 1 cm and 10 cm above the plane of the inlet surface 11, such as... Figure 3 The figure is schematically illustrated using the reference numeral d.

[0092] In use, the porous substrate 10 is initially positioned in the retainer 2, such that the inlet surface 11 communicates with the inlet chamber 15 and the outlet surface 12 communicates with the vacuum generator (e.g., vacuum cone 17). The upper inflatable collar 3 and the lower inflatable collar 4 can be inflated to secure the porous substrate 10.

[0093] Next, by using a vacuum generator to apply pressure to the outlet surface 12 of the porous substrate 10, a main gas flow is established from the inlet surface 11 to the outlet surface 12 through the porous substrate 10.

[0094] In addition, the annular air blade 30 is activated to generate a secondary gas flow downward onto the inlet surface 11, wherein the pressure and / or flow rate of the secondary gas flow has been set to a desired level.

[0095] The pressure and / or flow rate of the secondary gas stream can be constant throughout the processing of a particular porous substrate 10, or it can vary during the processing of the particular porous substrate 10.

[0096] For example, dry powder is sprayed into the inlet chamber 15 using nozzle 20 or sprayed into the inlet chamber, such that the dry powder is entrained in the main gas flow, passes through the turbulent zone generated by the secondary gas flow along the inlet chamber 15, and then passes through the inlet surface 11 of the porous substrate 10 to contact the porous structure.

[0097] The secondary gas stream can be active for the entire duration of dry powder spraying or for a portion of the dry powder spraying duration.

[0098] Although in the above example the secondary gas flow has been described as being generated by the annular air blade 30, alternative arrangements for generating a secondary gas flow on or across the inlet face 11 to create a turbulent zone at or above the inlet face 11 are also within the scope of this disclosure. Example

[0099] Figure 4 A graph showing the relative mass of the deposited dry powder as a function of the distance from the inlet surface of the porous substrate sample is presented.

[0100] The porous substrate is an aluminum titanate filter substrate supplied by Corning Incorporated. Diameter = 171.9 mm, Length = 152.4 mm.

[0101] A carrier coating was applied to a filter substrate. The carrier coating contained Cu-exchanged zeolite (CHA, SAR=18.5, supplied by Tosoh, Cu loading=3.3 wt%) suspended in water at a 9:1 ratio and stabilized γ-alumina (supplied by PIDC). The carrier coating had a d90 of 4 µm to 5 µm. The surface of the zeolite was modified using an aminosilane (see US11192793B2).

[0102] The carrier coating was applied according to EP3122458. The carrier coating was applied to the outlet end of the filter substrate to coat 80% of the filter volume, with a calcination loading of 1.58 g / in relative to the filter volume. -3 An additional carrier coating was applied to the inlet end of the filter substrate to coat 35% of the filter volume, with a calcination loading of 0.52 g / in relative to the filter volume. -3 The filter substrate was calcined at 500°C for 1 hour.

[0103] The dry powder was a mixture of zeolite (4µm d90 and SAR 23, purchased from Tosoh Corporation) and Silres MK powder (9µm d90 methyl silicone resin, purchased from Wacker), prepared at a 3:1 zeolite:silicone ratio. Under a constant airflow, the resulting mixed powder was sprayed from the inlet end onto a filter substrate coated with a carrier coating. The airflow forming the main gas flow was 300m. 3 / hr. Then the coated parts are calcined at 500°C for 1 hour.

[0104] The particle size measurements necessary to obtain the d90 of solid particles (e.g., zeolite or Silres MK powder) can be obtained through laser diffraction particle size analysis using a Malvern Mastersizer 3000, a volume-based technique (i.e., d90 can also be referred to as d(v, 0.90)) and applying a mathematical Mie theory model to determine the particle size distribution. The laser diffraction system works by determining the particle diameter based on a spherical approximation. For particle size measurements performed via laser diffraction particle size analysis, a diluted sample is prepared by sonicating in surfactant-free distilled water at 35 watts for 30 seconds.

[0105] The annular air vane 30 serves as the source of the secondary gas flow. The nozzle height h is always fixed at 200 cm. When the secondary gas flow is shut off (in... Figure 4 In the case marked "none", and at secondary gas flow pressures of 2 bar, 3.5 bar and 5 bar (for clarity only), Figure 4 (The result of 3.5 bar is omitted in the text) The sample of the filter substrate was processed.

[0106] Figure 4 This is a graph showing the relative mass of the deposited dry powder relative to the distance from the inlet surface of the filter substrate. The results were obtained by X-ray scanning the filter substrate before and after the application of the dry powder. In each scan, the radial average X-ray absorption was measured every 0.5 mm along the axis of the filter substrate. The pre-application measurements were then subtracted from the post-application measurements, and the results were normalized.

[0107] As from Figure 4 It can be seen that with the secondary gas flow closed, the deposition of dry powder shows a skewed distribution at the outlet end of the filter substrate, with the peak approximately 120 cm from the inlet surface. With the secondary gas flow set to 2 bar, other identical processing conditions result in the dry powder being distributed along the middle of the filter structure's length. With the secondary gas flow set to 5 bar, other identical processing conditions result in the deposition of dry powder, showing a skewed distribution towards the inlet end of the filter substrate, with the peak approximately 5 cm from the inlet surface, and secondary peeling approximately 55 cm.

[0108] Figure 5 The graphs showing the powder deposition ratio of the filter substrate tested at 0 bar, 2 bar, 3.5 bar, and 5 bar as a function of the secondary gas flow pressure are presented above. The powder deposition ratio was calculated as the normalized absorbance at 60 mm from the inlet surface divided by the normalized absorbance at 120 mm from the inlet surface.

[0109] As from Figure 5 It can be seen that there is a strong linear relationship between the pressure of the secondary gas flow and the powder deposition ratio, indicating that using the pressure of the secondary gas flow provides a reliable and controllable means of controlling the deposition location of dry powder in porous substrates.

[0110] like Figure 6 As shown, treating the porous substrate 10 with dry powder can lead to the accumulation of dry powder on the inlet surface 11, particularly on the ends of the walls that separate the inlet channels and / or on any channels that are blocked at their inlet ends.

[0111] Therefore, the annular air vane 30 can be activated to direct the gas flow downwards onto the inlet face 11 to blow away the dry powder accumulated on the inlet face 11 of the porous substrate 10. The vacuum generator can remain active during the activation of the annular air vane 30, such that the dry powder blown away from the inlet face 11 is entrained in the gas flow and passes through the inlet face 11 of the porous substrate 10.

[0112] like Figure 7 As shown, the result is that the inlet surface 11 can effectively remove the accumulation of dry powder.

[0113] After the dry powder has been sprayed into the inlet chamber 15 or after the spraying of dry powder into the inlet chamber has stopped (but the vacuum generator is still running), the annular air vane 30 may be activated to blow away the dry powder. Alternatively or additionally, the annular air vane 30 may be activated during the spraying of dry powder into the inlet chamber 15 or during the spraying of dry powder into the inlet chamber.

Claims

1. A method of applying a dry powder to a porous substrate having an inlet face at an inlet end and an outlet face at an outlet end, wherein the inlet face and the outlet face are separated by a porous structure, the method comprising the steps of: a) positioning the porous substrate in a holder such that the inlet face is in communication with an inlet chamber and the outlet face is in communication with a vacuum generator; b) establishing a primary gas flow through the porous substrate from the inlet face to the outlet face by applying a reduced pressure to the outlet face of the porous substrate using the vacuum generator; c) spraying the dry powder into or within the inlet chamber such that the dry powder is entrained in the primary gas flow and passes through the inlet face of the porous substrate to contact the porous structure; d) during the spraying of the dry powder, directing a secondary gas flow onto and / or across the inlet face of the porous substrate; and e) using the pressure and / or flow of the secondary gas flow to control the axial distribution of the dry powder deposited in the porous structure of the porous substrate.

2. The method of claim 1, wherein controlling the axial distribution of the dry powder comprises: - selecting a relatively high pressure and / or flow of the secondary gas flow to skew the axial distribution of the dry powder deposited in the porous structure towards the inlet end of the porous substrate; - selecting a relatively low pressure and / or flow of the secondary gas flow or deactivating the secondary gas flow to skew the axial distribution of the dry powder deposited in the porous structure towards the outlet end of the porous substrate; and - selecting a relatively intermediate pressure and / or flow of the secondary gas flow to obtain an intermediate axial distribution of the dry powder deposited in the porous structure.

3. The method of any preceding claim, wherein the secondary gas flow is active for: the entire duration of the spraying of the dry powder; or a portion of the duration of the spraying of the dry powder.

4. The method of any preceding claim, wherein the secondary gas flow remains active or is activated after the spraying of the dry powder has ceased in order to blow off dry powder accumulated on the inlet face of the porous substrate.

5. The method of claim 4, wherein the vacuum generator remains active during the activation of the secondary gas flow such that the dry powder blown off from the inlet face is entrained in the primary gas flow and passes through the inlet face of the porous substrate after the spraying of the dry powder has ceased.

6. The method of any preceding claim, wherein the secondary gas flow is configured as a 360° or substantially 360° gas flow.

7. The method of any preceding claim, wherein the secondary gas flow is configured to be directed onto the inlet face at a downward angle.

8. The method of any preceding claim, further comprising using an annular air blade to generate the secondary gas flow. ​ 9. The method of any preceding claim, wherein the dry powder is sprayed into or within the inlet chamber using a nozzle, and the spatial separation of the nozzle from the inlet face is held fixed when the pressure and / or the flow rate of the secondary gas stream is used to control the axial distribution of the dry powder.

10. The method of any preceding claim, further comprising continuously applying dry powder to a plurality of porous substrates, wherein for each porous substrate of the plurality of porous substrates, the pressure and / or the flow rate of the secondary gas stream is selected so as to control the axial distribution of the dry powder deposited in the porous structure of the porous substrate.

11. The method of claim 10, wherein the nozzle used to spray the dry powder is held at a fixed spatial separation from the inlet face of the plurality of porous substrates.

12. An apparatus for applying dry powder to a porous substrate, the porous substrate having an inlet face at an inlet end and an outlet face at an outlet end, wherein the inlet face and the outlet face are separated by a porous structure, the apparatus comprising: a) a holder for holding the porous substrate; b) an inlet chamber in communication with the inlet face; c) a vacuum generator in communication with the outlet face and for establishing a primary gas stream through the porous substrate from the inlet face to the outlet face; d) a spraying device for spraying the dry powder into or within the inlet chamber; and e) a secondary gas source for establishing a secondary gas stream on and / or across the inlet face of the porous substrate; and f) a controller for selecting a pressure and / or a flow rate of the secondary gas stream to control an axial distribution of the dry powder deposited in the porous structure of the porous substrate.

13. The apparatus of claim 12, wherein the secondary gas source is oriented to direct a gas stream at a downward angle onto the inlet face of the porous substrate.

14. The apparatus of claim 12 or claim 13, wherein the secondary gas source is configured to emit a 360° or substantially 360° gas stream.

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

16. The apparatus of claim 15, wherein a plane of a gas outlet of the ring air blade is positioned between 1 cm and 10 cm above a plane of the inlet face.

17. The apparatus of claim 15 or claim 16, wherein the ring air blade is located within the inlet chamber or between the inlet chamber and the inlet face of the porous substrate.

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