WO2024072765A1

WO2024072765A1 - Particulate filter articles with fumed silica deposits and methods thereof

Info

Publication number: WO2024072765A1
Application number: PCT/US2023/033655
Authority: WO
Inventors: Hannah Diane ALEXANDER; Jia Liu; Dale Robert Powers
Original assignee: Corning Incorporated
Priority date: 2022-09-30
Filing date: 2023-09-26
Publication date: 2024-04-04

Abstract

Filtration articles, and methods for making filtration articles, include particles of inorganic material, which include fumed silica particles, deposited onto porous cell walls inside a honeycomb structure of a filter body for improved filtration performance.

Description

PARTICULATE FILTER ARTICLES WITH FUMED SILICA DEPOSITS AND METHODS THEREOF

Cross Reference to Related Application

[0001] This application claims the benefit of priority under 35 U.S.C. §119 of U.S. Provisional Application Serial No. 63/412049, filed on September 30, 2022, the content of which is relied upon and incorporated herein by reference in its entirety.

BACKGROUND

Field

[0002] The present specification relates to articles for emissions treatment, the articles comprising porous ceramic walls, such as plugged honeycomb filter bodies, comprising inorganic deposits comprising fumed silica particles disposed on walls defining inlet channels of the plugged honeycomb filter bodies, and methods of making and using such articles.

Technical Background

[0003] Wall flow filters are employed to remove particulates from fluid exhaust streams, such as from combustion engine exhaust. Examples include ceramic soot filters used to remove particulates from diesel engine exhaust gases; and gasoline particulate filters (GPF) used to remove particulates from gasoline engine exhaust gases. For wall flow filters, exhaust gas to be filtered enters inlet cells and passes through the cell walls to exit the filter via outlet channels, with the particulates being trapped on or within the inlet cell walls as the gas traverses and then exits the filter.

[0004] GPFs can be used in conjunction with multiport injection engines or gasoline direct injection (GDI) engines, which emit more particulates than conventional gasoline engines. [0005] Emissions treatment articles that utilize an aftertreatment component, such as a GPF, seek to provide high filtration efficiency (FE) without impacting pressure drop penalties from the exhaust line.

SUMMARY

[0006] Aspects of the disclosure pertain to porous filter bodies and methods for their manufacture and use.

[0007] In one aspect, a method is disclosed herein for making a filtration article, the method comprising depositing particles comprised of inorganic material comprising fumed silica particles onto porous cell walls inside a honeycomb structure of a filter body, the cell walls defining a plurality of axial channels, wherein a first subset of channels is sealed at a first end and second subset of channels is sealed at a second end opposite the first end.

[0008] In embodiments, the inorganic deposits extend over all of the pores that extend to the surface of the walls. In embodiments, some of the inorganic deposits penetrate into the walls to a penetration depth of less than 1/10 of an average thickness of the wall. In embodiments, some of the inorganic deposits penetrate into the walls to a penetration depth of 1/1000 to 1/10 of an average thickness of the wall.

[0009] In another aspect, a filtration article is disclosed herein comprising: a plugged honeycomb filter body comprising intersecting porous ceramic walls defining a plurality of channels comprised of inlet channels, which are plugged at a distal end of the plugged honeycomb filter body, and outlet channels, which are plugged at a proximal end of the plugged honeycomb filter body, wherein the porous ceramic walls comprise a plurality of pores, wherein some of the pores extend to surfaces of the walls which define the inlet channels; and fumed silica deposits disposed on surfaces of the walls which define the inlet channels of the plugged honeycomb filter body.

[0010] In another aspect, a filtration article is disclosed herein comprising a plugged honeycomb filter body comprising: porous ceramic walls; a first set of channels which are plugged at a distal end of the plugged honeycomb filter body; and a second set of channels which are plugged at a proximal end of the plugged honeycomb filter body; and inorganic deposits comprising fumed silica particles disposed on walls defining a first subset of channels of the plug honeycomb filter body at a loading of less than or equal to 20 grams of the inorganic deposits per liter of the plugged honeycomb filter body, wherein a clean filtration efficiency of the filtration article is greater than or equal to 90% as measured by a clean filtration efficiency test.

[0011] In embodiments, the inorganic deposits are positioned on the walls to a wall depth of less than or equal to 40 micrometers. In embodiments, a loading of the inorganic deposits disposed within the plugged honeycomb filter body is less than or equal to 20 grams of the inorganic deposits per liter of the plugged honeycomb filter body. In embodiments, the inorganic deposits comprise a median pore size in a range of greater than or equal to 0.1 micrometers to less than or equal to 5 micrometers. In embodiments, the porous ceramic walls comprise a porosity of greater than or equal to 40% to less than or equal to 70%. In embodiments, the inorganic deposits are comprised of nanoparticles present in the form of agglomerates.

[0012] In another aspect, a filtration article is disclosed herein comprising: a plugged honeycomb filter body comprising: porous ceramic walls which form channels, wherein some of the channels are plugged at a distal end of the plugged honeycomb filter body, and other channels are plugged at a proximal end of the plugged honeycomb filter body; and, inorganic deposits comprising fumed silica disposed on walls defining a subset of channels of the plugged honeycomb filter body.

[0013] In embodiments, a loading of the inorganic deposits disposed within the plugged honeycomb filter body is less than or equal to 20 grams of the inorganic deposits per liter of the plugged honeycomb filter body. In embodiments, the inorganic deposits comprise a median pore size in a range of greater than or equal to 0.1 micrometers to less than or equal to 5 micrometers. In embodiments, the porous ceramic walls comprise a porosity of greater than or equal to 40% to less than or equal to 70%. In embodiments, the inorganic deposits are comprised of nanoparticles present in the form of agglomerates.

[0014] Additional features and advantages will be set forth in the detailed description, which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, comprising the detailed description, which follows, the claims, as well as the appended drawings. [0015] It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate the various embodiments described herein, and together with the description serve to explain the principles and operations of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIGS. 1 A-1D show SEM images of four different fumed silica materials.

[0017] FIG. 2A schematically depicts settling volume ratios of various fumed silica dispersions after 5, 7 and 13 days.

[0018] FIG. 2B shows a photograph of a dispersion which settled into a distinct interface, and a photograph of a dispersion which retained a diffused interface.

[0019] FIG. 3A schematically shows filtration efficiency for various loading of as- deposited alumina material.

[0020] FIG. 3B graphically shows the change in filtration efficiency for the examples of FIG. 3 A after exposure to a water durability test.

[0021] FIG. 4A shows filtration performance of four exemplary GPF filter bodies in which high surface area (>100 m²/g) fumed silica-based formulations were used to deliver various loadings of fumed silica deposits.

[0022] FIG. 4B graphically shows the change in filtration efficiency for the examples of FIG. 4 A after exposure to a water durability test.

[0023] FIG. 5A shows filtration performance of two exemplary GPF filter bodies treated with fumed silica-based formulations, one with 1% TEA added, the other with no TEA added, to deliver various loadings of fumed silica deposits.

[0024] FIG. 5B graphically shows the change in filtration efficiency for the examples of FIG. 5 A after exposure to a water durability test. [0025] FIGS. 6A-6B graphically show filtration efficiency and change in filter efficiency after a water exposure durability test for an alumina example and two fumed silica examples at various inorganic loadings.

[0026] FIG. 6C shows as-deposited FE vs. deposition time of the aerosol of the formulation directed at the filter bodies of FIGS. 6A-6B.

[0027] FIG. 6D shows FE vs. dP after the subject filter bodies of FIGS. 6A-6C were cured at 200 °C.

[0028] FIGS. 7A-7C are SEM images of internal cell wall surfaces of the GPF filter body coated with exemplary fumed silica deposits.

[0029] FIG. 8 schematically depicts a plugged honeycomb filter body in the form of a wall-flow particulate filter according to embodiments disclosed and described herein;

[0030] FIG. 9 is a cross-sectional longitudinal view (in the axial direction) of a portion of the filter body shown in FIG. 8.

[0031] FIG. 10 is a flowchart depicting an exemplary embodiment of a process of forming deposits of inorganic material on a substrate according to embodiments disclosed herein.

DETAILED DESCRIPTION

[0032] Reference will now be made in detail to embodiments of articles for emissions treatment, for example, filtration articles, comprising a plugged honeycomb filter body comprising inorganic deposits disposed on walls defining inlet channels of the plugged honeycomb filter body, the inorganic deposits comprising fumed silica particles, embodiments of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts.

[0033] Aspects herein relate to articles, emissions treatment articles, in particular filtration articles, which are effective for filtration of particulates from gaseous streams. Aspects also relate to manufacture of such articles and their use.

[0034] Advantageously, articles disclosed herein including inorganic deposits disposed on walls defining inlet channels of a plugged honeycomb filter bodies, the inorganic deposits comprising fumed silica particles, which provide high filtration efficiency. [0035] The “inorganic deposits” of the honeycomb filter body are non-engine inorganic deposits. That is, the inorganic deposits of the honeycomb filter body are not soot or metals or the like coming from the engine exhaust itself. Rather, the inorganic deposits of the honeycomb filter body are present from manufacture of the articles itself. The inorganic deposits comprise fumed silica particles. In one or more embodiments the inorganic deposits of the honeycomb body are free from rare earth oxides such as ceria, lanthana, and yttria. In one or more embodiments, the inorganic deposits are free from catalyst, for example, an oxidation catalyst such as a platinum group metal (e.g., platinum, palladium and rhodium) or a selective catalytic reduction catalyst such as a copper, a nickel or an iron promoted molecular sieve (e.g., a zeolite). In other embodiments, the filter body further comprises one or more catalytic materials disposed in or on the porous walls of the honeycomb body, and/or in or on the inorganic deposits.

[0036] Disclosed herein are methods for making a filtration article, the method comprising: depositing particles comprised of inorganic material comprising fumed silica particles onto porous cell walls inside a honeycomb structure of a filter body, the cell walls defining a plurality of axial channels, wherein a first subset of channels is sealed at a first end and second subset of channels is sealed at a second end opposite the first end.

[0037] In embodiments, the fumed silica particles are deposited as aggregates of fumed silica primary particles, the primary particles having a particle size of 5 nm to 250 nm, and in some embodiments, 5 nm to 150 nm.

[0038] In embodiments, the fumed silica particles are deposited as aggregates of fumed silica primary particles, the primary particles having a BET surface area of 5 to 500 m²/g, in some embodiments a BET surface area in a range of 10 to 400 m²/g, and in some embodiments a BET surface area in a range of 20 to 400 m²/g.

[0039] In some of these embodiments, the fumed silica particles are deposited as aggregates of fumed silica primary particles, the primary particles having a BET surface area of 20 m²/gto 400 m²/g. In some of these embodiments, the fumed silica particles are deposited as aggregates of fumed silica primary particles, the primary particles having a BET surface area of 23 m²/gto 380 m²/g. [0040] In embodiments, the fumed silica particles are deposited as aggregates of fumed silica primary particles, the primary particles having a particle size of 7 nm to 124 nm.

[0041] In embodiments, the particles further comprise a binder material. In some of these embodiments, the binder material is present at a loading of 10 to 60 %, in some embodiments 10 to 29 %, and in some embodiments 30 to 60 %, by weight of the inorganic material in the particles.

[0042] In some of these embodiments, the methods further comprise heating the filter body sufficient to cause the binder to fuse at least some of the particles to each other, to the porous cell walls, or both.

[0043] In embodiments, less than or equal to 3.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 90%.

[0044] In embodiments, less than or equal to 2.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 90%.

[0045] In embodiments, less than or equal to 1.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 90%.

[0046] In embodiments, less than or equal to 0.5 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 90%.

[0047] In embodiments, 0.5 to 3.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 90%.

[0048] In embodiments, 0.5 to 2.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 90%.

[0049] In embodiments, 0.5 to 1.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 90%. [0050] In embodiments, less than or equal to 0.5 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 90%.

[0051] In embodiments, less than or equal to 4.5 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 95%.

[0052] In embodiments, less than or equal to 4.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 95%.

[0053] In embodiments, less than or equal to 3.5 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 95%.

[0054] In embodiments, less than or equal to 3.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 95%.

[0055] In embodiments, less than or equal to 2.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 95%.

[0056] In embodiments, less than or equal to 1.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 95%.

[0057] In embodiments, 0.75 to 4.5 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 95%.

[0058] In embodiments, 0.75 to 4.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 95%.

[0059] In embodiments, 0.75 to 3.5 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 95%. [0060] In embodiments, 0.75 to 3.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 95%.

[0061] In embodiments, 0.75 to 2.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 95%.

[0062] In embodiments, less than or equal to 6.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 98%.

[0063] In embodiments, less than or equal to 5.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 98%.

[0064] In embodiments, less than or equal to 4.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 98%.

[0065] In embodiments, less than or equal to 3.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 98%.

[0066] In embodiments, less than or equal to 2.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 98%.

[0067] In embodiments, less than or equal to 2.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 98%.

[0068] In embodiments, 1.0 to 6.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 98%.

[0069] In embodiments, 1.0 to 5.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 98%. [0070] In embodiments, 1.0 to 4.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 98%.

[0071] In embodiments, 1.0 to 3.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 98%.

[0072] In embodiments, 1.0 to 2.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 98%.

[0073] In embodiments, less than 8.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 99.0%.

[0074] In embodiments, less than or equal to 7.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 99.0%.

[0075] In embodiments, less than or equal to 6.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 99.0%.

[0076] In embodiments, less than or equal to 5.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 99.0%.

[0077] In embodiments, less than or equal to 4.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 99.0%.

[0078] In embodiments, less than or equal to 3.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 99.0%.

[0079] In embodiments, 2.0 to 8.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 99.0%. [0080] In embodiments, 2.0 to 7.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 99.0%.

[0081] In embodiments, 5.0 to 7.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 99.0%.

[0082] In embodiments, 7.0 to 8.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 99.0%.

[0083] In embodiments, 2.0 to 3.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 99.0%.

[0084] In another aspect, a filtration article is disclosed herein comprising a plugged honeycomb filter body comprising intersecting porous ceramic walls defining a plurality of channels comprised of inlet channels, which are plugged at a distal end of the plugged honeycomb filter body, and outlet channels, which are plugged at a proximal end of the plugged honeycomb filter body, wherein the porous ceramic walls comprise a plurality of pores, wherein some of the pores extend to surfaces of the walls which define the inlet channels; and fumed silica deposits disposed on surfaces of the walls which define the inlet channels of the plugged honeycomb filter body.

[0085] In embodiments, the inorganic deposits extend over a majority of the pores that extend to the surface of the walls.

[0086] In embodiments, the inorganic deposits extend over all of the pores that extend to the surface of the walls.

[0087] In embodiments, some of the inorganic deposits penetrate into the walls to a penetration depth of less than 1/10 of an average thickness of the wall.

[0088] In embodiments, some of the inorganic deposits penetrate into the walls to a penetration depth of 1/1000 to 1/10 of an average thickness of the wall.

[0089] In another aspect, a filtration article is disclosed herein comprising: a plugged honeycomb filter body comprising porous ceramic walls; channels which are plugged at a distal end of the plugged honeycomb filter body; and channels which are plugged at a proximal end of the plugged honeycomb filter body; and inorganic deposits comprising fumed silica disposed on walls defining a subset of channels of the plugged honeycomb filter body.

[0090] In embodiments, the inorganic deposits are positioned on the walls to a wall depth of less than or equal to 40 micrometers.

[0091] In embodiments, a loading of the inorganic deposits disposed within the plugged honeycomb filter body is less than or equal to 20 grams of the inorganic deposits per liter of the plugged honeycomb filter body.

[0092] In embodiments, the inorganic deposits comprise a median pore size in a range of greater than or equal to 0.1 micrometers to less than or equal to 5 micrometers.

[0093] In embodiments, the porous ceramic walls comprise a porosity of greater than or equal to 40% to less than or equal to 70%.

[0094] In embodiments, the inorganic deposits are comprised of nanoparticles present in the form of agglomerates.

[0095] In another aspect, a filtration article is disclosed herein comprising: a plugged honeycomb filter body comprising: porous ceramic walls, channels which are plugged at a distal end of the plugged honeycomb filter body, and channels which are plugged at a proximal end of the plugged honeycomb filter body; and inorganic deposits comprising fumed silica particles disposed on walls defining a first subset of channels of the plugged honeycomb filter body at a loading of less than or equal to 20 grams of the inorganic deposits per liter of the plugged honeycomb filter body; wherein a clean filtration efficiency of the filtration article is greater than or equal to 90% as measured by a clean filtration efficiency test.

[0096] In embodiments, a loading of the inorganic deposits disposed within the plugged honeycomb filter body is less than or equal to 20 grams of the inorganic deposits per liter of the plugged honeycomb filter body.

[0097] In embodiments, the inorganic deposits comprise a median pore size in a range of greater than or equal to 0.1 micrometers to less than or equal to 5 micrometers.

[0098] In embodiments, the porous ceramic walls comprise a porosity of greater than or equal to 40% to less than or equal to 70%. [0099] In embodiments, the inorganic deposits are comprised of nanoparticles present in the form of agglomerates.

[00100] Fumed silica materials of various types and/or sources were evaluated, as shown in Table 1. FIGS. 1 A-1D show SEM images of fumed silica materials M-5, PL22, OF Precursor Soot 1, and OF Precursor Soot 2, respectively. OF Precursor Soot 1 and 2 were obtained from two separate optical fiber production plants.

[00101] The stability of dispersions made with fumed silica was evaluated are summarized in FIG. 2Ai, wherein each of the dispersions was prepared using the following procedure: (1) Mix fumed silica with 200-proof ethanol at 11 wt% or 5 wt%, according to weight percentages specified for each condition in the chart in FIG. 2A; for higher surface area silica, the concentration was limited to 5% to prevent gelling; (2) For half of the conditions, add 1% of triethanolamine (TEA) and 1% of Pluronic L-121 triblock copolymer, based on the combined weight of fumed silica and ethanol; for the other half, skip this step; (3) Add 15% of Dowsil® 2405 binder to each dispersion, based on the weight of fumed silica in the dispersion. The dispersions were allowed to sit undisturbed and the amount of settling of silica solid was recorded over time. [00102] FIG. 2A shows “settling volume ratio” which is defined as the ratio of the volume of the translucent liquid at the bottom containing silica to the total volume of the dispersion. As seen in FIG. 2B, in some cases the solid settled to create a “distinct” interface in some cases while in other cases, the interface remained “diffused” and the settled volume was estimated. In FIG. 2A, solid bars indicate a “distinct” interface and diffused bars indicate a “diffused” interface. The preferred performance is to not settle and to remain near 1.0. Most of the dispersions exhibited excellent stability over 13 days of observation. The dispersion with 11% BF26, 1% TEA and 1% triblock showed significant settling, but the dispersion with 11% BF26 and without TEA or triblock showed good stability, suggesting that silica-based dispersions may be more stable without adding dispersants currently which may be used in inorganic material dispersions wherein all or a majority portion of the inorganic material particles in the dispersion are alumina particles.

[00103] As used herein, “fumed silica” refers to nanoparticles of amorphous silica produced pyrogenically (pyrogenic silica), as well as branched or chainlike three-dimensional secondary particles comprised of fused amorphous silica nanoparticles (primary particles), as well as tertiary particles comprised of agglomerates of the secondary particles and/or nanoparticles. Fumed silica is typically in the form of a powder of extremely low bulk density and high surface area. The primary particle size is 5 nm to 250 nm, and in some embodiments, 5-150 nm, with a BET surface area of 20-600 m²/g. The nanoparticles are non-porous, and in one or more embodiments have a volumetric (or bulk) density of 160-190 kg/m³. Fumed silica comprises finely divided amorphous silicon dioxide particles which may be produced by high temperature in an oxygen-hydrogen flame, such as via flame pyrolysis of silicon tetrachloride (SiC14), or from quartz sand vaporized in a 3000 °C electric arc. Fumed silica may be obtained from producers such as Dow Corning, Cabot Corporation, and Wacker Chemie.

[00104] Various inorganic materials were deposited on various gasoline particulate filter (GPF) bodies (plugged honeycomb bodies) and then cured at 200° C for one hour. The coated and cured parts were tested. The gasoline particulate filter bodies were 200/8 plugged honeycomb bodies having a porosity of 55% and measured by mercury intrusion, with a diameter of 4.252 inches and an axial length of 4.724 inches. [00105] As a baseline case for reference, an alumina-based formulation (with no fumed silica) was deposited onto surfaces of the cell walls of the inlet channels of GPF parts via atomization of the dispersion, transport to the filter body via carrier gas, and filtration deposition as the filter traps solid particles from the dispersion being transported thereto, wherein the porous honeycomb walls allow the carrier gas to pass through the cell walls and out of the filter body. The formulation contained 11% of alumina (the alumina particles having a median particle size d50 between 0.4-0.5 pm) in ethanol, along with 1% of TEA, 1% of Pluronic® L-121, and 15% Dowsil® 2405 (based on alumina weight). The naming convention of the dispersion formulations is presented herein in the format of “Inorganic Material Type, Inorganic Material wt%” - TEA wt% - Pluronic L-121 wt% - Dowsil 2405 wt%”, where the Dowsil wt% is “ratio” to the weight of the inorganic material: for example, “AL30, 11-1-1- 40”, wherein the amount of Dowsil 2405 in this sample is 40% of that of the inorganic material, i.e. approximately 0.4 * 11% or about 4.4%.

[00106] As shown in FIG. 3A, 8 g/L or more of inorganic material loading (grams of inorganic material / overall outer dimension volume of the GPF filter body part) was required o reach a “clean” filtration efficiency (without engine-generated soot or other particles) or “as- deposited FE” of 99% or higher.

[00107] As shown in FIG. 3B, 7 g/L of inorganic material loading was required to maintain a clean filtration efficiency of a loaded gasoline particulate filter body which has been subjected to a durability test that involves saturation of the filter body by water to within 1% of the filtration efficiency value before being subjected to water saturation (i.e. <1% water saturation FE loss).

[00108] Table 2 lists various fumed silica dispersions which w atomized and delivered to various GPF filter bodies in a similar manner to the GPF bodies that were loaded with alumina. [00109] Table 2

[00110] FIG. 4A shows filtration performance of four exemplary GPF filter bodies in which high surface area (>100 m²/g) fumed silica-based formulations were used to deliver fumed silica deposits inside the honeycomb cells. With three fumed silica materials (EH-5, M- 5, and LM-150) having the highest surface areas, an as-deposited (“clean”) FE of greater than 99% (>99%) was achieved for the GPF filter bodies with a deposited inorganic loading of fumed silica as little as 2 g/L or even less, which is very desirable, although as seen in FIG. 4B the water saturation FE loss was relatively high, possibly due to the high surface area requiring more of the current binder.

[00111] FIGS. 5 A and 5B show filtration performance of two exemplary GPF filter bodies in which two formulations (FS1 and FS7) based on PL22 silica were used to deliver fumed silica deposits inside the honeycomb cells of the GPF filter bodies. The two formulations were the same except that, as seen in Table 2, 1% TEA was added in FS1 and no TEA was added in FS7.

[00112] As seen in FIGS. 5A and 5B, GPF filter bodies treated with FS7 exhibited significantly better FE-loading efficiency and water resistance: loading to attain >99% as- deposited FE was 6-7 g/L for FS1 and about 10 g/L for FS7 and loading to maintain <1% water saturation FE loss was about 7 g/L for FS7 and 10-11 g/L for FS1. For these relatively larger size silica particles with lower BET surface area, the absence of TEA from the formulation was advantageous for filtration performance; such embodiments are suitable in a manufacturing environment in the sense that TEA could volatize during the inorganic material deposition process and could potentially increase the risk of safety and environmental issues downstream in the exhaust system and/or ducting of the deposition apparatus.

[00113] With three fumed silica materials (EH-5, M-5, and LM-150) having the highest surface areas, an as-deposited (“clean”) filtration efficiency (FE) of greater than 99% (>99%) was achieved for the GPF filter bodies having a deposited inorganic loading of fumed silica as little as 2 g/L or even less, which is very desirable, although as seen in FIG. 5B the water saturation FE loss was relatively high, possibly due to the high surface area requiring more of the current binder. FIGS. 6A-6D show filtration performance of two exemplary GPF filter bodies in which two formulations (FS9 and FS10) based on OF Precursor Soot 1 silica were used to deliver fumed silica deposits inside the honeycomb cells of the GPF filter bodies. The two formulations were the same except for different silica wt%: 11% and 6%, respectively. For these two examples, 40% binder was used in each formulation to match with the OF Precursor Soot 1 silica soot having a much higher surface area (24.6 m²/g) than the alumina (9- 10 m²/g) described above.

[00114] FIGS. 6A-6D also include filtration performance of the baseline alumina-based formulation (AL-B1) for comparison.

[00115] As seen in FIG. 6A, the two silica soot based formulations attained much higher as-deposited FE than the alumina-based formulation at loadings lower than 6 g/L/.

[00116] FIG. 6B shows any FE changes after water saturation, wherein the following were observed: (1) FS10 with 6% (OF Precursor Soot 1) silica showed substantially less FE loss after water saturation than FS9 with 11% (OF Precursor Soot 1) silica; (2) The two formulations reached <5% water saturation FE loss at about 3.5 g/L and about 5 g/L loadings, respectively; (3) FS10 attained 1.5% loss at 6.2 g/L loading, similar to the alumina baseline; (4) although FS9 showed slightly more FE loss than the alumina baseline at all loadings >6 g/L, it eventually reached <1% loss at higher loading, for example about 10 g/L loading.

[00117] FIG. 6C shows as-deposited FE vs. deposition time of the aerosol of the formulation directed at the filter bodies. The same liquid flow rate (12 g/min) (of formulation delivered to the aerosol stream) was used for all three formulations; for FS10, even though the solid concentration was only 6% (vs. 11% for FS9), there was no deposition time required (no deposition time penalty).

[00118] FIG. 6D shows FE vs. dP after the subject filter bodies were cured at 200 °C. FS9 and FS10 exhibited higher FE than the alumina baseline at for the same dP in the range where there is overlap. For example, in FIG. 6D at dP of about 220 Pa, the alumina filtration material (A130) had an FE of about 97.2% whereas the fumed silica materials (N6) had FEs of about 98%. In other words, the red and green curves are above the blue curve in most cases, specifically in these embodiments for pressure drop across the filter body of 245 Pa and lower. FIGS. 7A-7C are SEM images of internal cell wall surfaces of the GPF filter body coated with FS10 (99.4% as-deposited FE). FIG. 7B shows that spherical or nearly spherical agglomerates were formed from the silica soot and as seen in FIGS. 7A and 7C the agglomerates were deposited on the GPF cell walls, serving to block pore entrances at the cell wall surfaces, which without having the need to be bound by theory, is believed to provide high filtration efficiency. Furthermore, two GPF filter body parts coated with FS10 were exposed to thermal aging (heat up to 1050 °C, held at about 1050 °C for 6 hours, cooled or allowed to cool down to 200 °C; repeat cycle one more time) . As reflected in Table 3, 210729-22 was provided with fumed silica deposits, cured at 200 C for 1 hour, and thermally aged at 1050 C which yielded a final FE which was 1.20% lower than the as-deposited FE for the same formulation. 210729-24 was provided with fumed silica deposits, cured at 200 C for 1 hour, then water saturation tested (which included 650 C heat treatment, water saturation, and subsequent drying at 200 C), and thermal aging at 1050 C, which yielded a final FE which was 2.64% lower than the as-deposited FE for the same formulation. As a reference, alumina-based deposits were imparted to a GPF filter body which was also similarly tested, which exhibited 3.24% FE loss after thermal aging.

[00119] Table 3. Inorganic deposit formulations based on various fumed silica materials

[00120] According to an aspect, at least a portion of the inorganic deposits which are comprised of fumed silica particles, and in one or more embodiments consist essentially of fumed silica particles, and a clean filtration efficiency of the filtration article is greater than or equal to 90% as measured by a clean filtration efficiency test.

[00121] The porous ceramic walls having an average wall thickness. In one or more embodiments, some of the inorganic deposits penetrate into the walls to a penetration depth of less than 1/10 of an average thickness of the wall. In one or more embodiments, some of the inorganic deposits penetrate into the walls to a penetration depth of 1/1000 to 1/10 of an average thickness of the wall.

[00122] In embodiments, the inorganic deposits comprise fumed silica particles, either alone or optionally in combination with one or more other inorganic materials, such as one or more ceramic or refractory materials. In embodiments, the inorganic deposits is disposed on the walls to provide enhanced filtration efficiency, both locally through and at the wall and globally through the honeycomb body, at least in the initial use of the honeycomb body as a filter following a clean state, or regenerated state, of the honeycomb body, for example such as before a substantial accumulation of ash and/or soot occurs inside the honeycomb body after extended use of the honeycomb body as a filter.

[00123] In one aspect, the filtration material is present as a layer disposed on the surface of one or more of the walls of the honeycomb structure. The layer in embodiments is porous to allow the gas flow through the wall. In embodiments, the layer is present as a continuous coating over at least part of the, or over the entire, surface of the one or more walls. In embodiments of this aspect, the filtration material is flame-deposited filtration material. [00124] In another aspect, the filtration material is present as a plurality of discrete regions of filtration material disposed on the surface of one or more of the walls of the honeycomb structure. The filtration material may partially block a portion of some of the pores of the porous walls, while still allowing gas flow through the wall. In embodiments of this aspect, the filtration material is aerosol-deposited filtration material. In some preferred embodiments, the filtration material comprises a plurality of inorganic particle agglomerates, wherein the agglomerates are comprised of inorganic or ceramic or refractory material. In embodiments, the agglomerates are porous, thereby allowing gas to flow through the agglomerates. The agglomerates preferably comprise fumed silica nanoparticles, and in one or more embodiments consist essentially of fumed silica nanoparticles.

[00125] In embodiments, a honeycomb body comprises a porous ceramic honeycomb body comprising a first end, a second end, and a plurality of walls having wall surfaces defining a plurality of inner channels. A deposited material such as a filtration material, such as inorganic deposits, which may be a porous inorganic layer, is disposed on one or more of the wall surfaces of the honeycomb body. The inorganic deposits, which may be a continuous porous inorganic layer, has a porosity in a range of from about 20% to about 95%, or from about 25% to about 95%, or from about 30% to about 95%, or from about 40% to about 95%, or from about 45% to about 95%, or from about 50% to about 95%, or from about 55% to about 95%, or from about 60% to about 95%, or from about 65% to about 95%, or from about 70% to about 95%, or from about 75% to about 95%, or from about 80% to about 95%, or from about 85% to about 95%, from about 30% to about 95%, or from about 40% to about 95%, or from about 45% to about 95%, or from about 50% to about 95%, or from about 55% to about 95%, or from about 60% to about 95%, or from about 65% to about 95%, or from about 70% to about 95%, or from about 75% to about 95%, or from about 80% to about 95%, or from about 85% to about 95%, or from about 20% to about 90%, or from about 25% to about 90%, or from about 30% to about 90%, or from about 40% to about 90%, or from about 45% to about 90%, or from about 50% to about 90%, or from about 55% to about 90%, or from about 60% to about 90%, or from about 65% to about 90%, or from about 70% to about 90%, or from about 75% to about 90%, or from about 80% to about 90%, or from about 85% to about 90%, or from about 20% to about 85%, or from about 25% to about 85%, or from about 30% to about 85%, or from about 40% to about 85%, or from about 45% to about 85%, or from about 50% to about 85%, or from about 55% to about 85%, or from about 60% to about 85%, or from about 65% to about 85%, or from about 70% to about 85%, or from about 75% to about 85%, or from about 80% to about 85%, or from about 20% to about 80%, or from about 25% to about 80%, or from about 30% to about 80%, or from about 40% to about 80%, or from about 45% to about 80%, or from about 50% to about 80%, or from about 55% to about 80%, or from about 60% to about 80%, or from about 65% to about 80%, or from about 70% to about 80%, or from about 75% to about 80%, and a continuous layer of the inorganic deposits has an average thickness of greater than or equal to 0.5 pm and less than or equal to 50 pm, or greater than or equal to 0.5 pm and less than or equal to 45 pm, greater than or equal to 0.5 pm and less than or equal to 40 pm, or greater than or equal to 0.5 pm and less than or equal to 35 pm, or greater than or equal to 0.5 pm and less than or equal to 30 pm, greater than or equal to 0.5 pm and less than or equal to 25 pm, or greater than or equal to 0.5 pm and less than or equal to 20 pm, or greater than or equal to 0.5 pm and less than or equal to 15 pm, greater than or equal to 0.5 pm and less than or equal to 10 pm. Average thickness may be determined by an overall average thickness (all channels in the honeycomb body) along entire axial length from inlet to outlet. Various embodiments of honeycomb bodies and methods for forming such honeycomb bodies will be described herein with specific reference to the appended drawings. [00126] The material in embodiments comprises a filtration material comprising fumed silica, and in embodiments comprises an inorganic layer comprising fused silica. According to one or more embodiments, the inorganic layer provided herein comprises a discontinuous layer formed from the inlet end to the outlet end comprising discrete and disconnected patches of material or filtration material and binder comprised of aggregates primary particles, secondary particles, and/or tertiary particles of fumed silica, and may comprise agglomerates of such aggregates, and in one or more embodiments the aggregates are substantially spherical. In one or more embodiments, the primary particles are non- spherical. In one or more embodiments, "substantially spherical" refers to an agglomerate having a circularity in cross section in a range of from about 0.8 to about 1 or from about 0.9 to about 1, with 1 representing a perfect circle. In one or more embodiments, 75% of the primary particles deposited on the honeycomb body have a circularity of less than 0.8. In one or more embodiments, the aggregate particles or agglomerates deposited on the honeycomb body have an average circularity greater than 0.9, greater than 0.95, greater than 0.96, greater than 0.97, greater than 0.98, or greater than 0.99.

[00127] Circularity can be measured using a scanning electron microscope (SEM). The term "circularity of the cross-section (or simply circularity)" is a value expressed using the equation shown below. A circle having a circularity of 1 is a perfect circle. Circularity=(47t><cross-sectional area)/(length of circumference of the cross-section)².

[00128] In one or more embodiments, the "filtration material" provides enhanced filtration efficiency to the honeycomb body, both locally through and at the wall and globally through the honeycomb body. In one or more embodiments, "filtration material" is not by itself considered to be catalytically active in that it does not react with components of a gaseous mixture of an exhaust stream. In one or more embodiments, the filtration material is coated with catalytic material.

[00129] As used in this specification and the appended claims, the singular forms "a", "an", and "the" encompass embodiments having plural referents, unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise. [00130] As used herein, "have", "having", "include", "including", "comprise", "comprising" or the like are used in their open ended sense, and generally mean "including, but not limited to".

[00131] A "honeycomb body," as referred to herein, comprises a ceramic honeycomb structure of a matrix of intersecting walls that form cells which define channels. The ceramic honeycomb structure can be formed, extruded, or molded from a plasticized ceramic or ceramic-forming batch mixture or paste. A honeycomb body may comprise an outer peripheral wall, or skin, which was either extruded along with the matrix of walls or applied after the extrusion of the matrix. A filter body comprise an unplugged honeycomb structure or a plugged honeycomb structure. For example, a honeycomb body can be a plugged ceramic honeycomb structure which forms a filter body comprised of cordierite or other suitable ceramic material. A plugged honeycomb body has one or more channels plugged at one, or both ends of the body. [00132] A honeycomb body of one or more embodiments may comprise a honeycomb structure and deposited material such as a filtration material, which may be a porous inorganic layer disposed on one or more walls of the honeycomb structure. In embodiments, the deposited material such as a filtration material, which may be a porous inorganic layer is applied to surfaces of walls present within honeycomb structure, where the walls have surfaces that define a plurality of inner channels.

[00133] The inner channels, when present, may have various cross-sectional shapes, such as circles, ovals, triangles, squares, pentagons, hexagons, or tessellated combinations or any of these, for example, and may be arranged in any suitable geometric configuration. The inner channels, when present, may be discrete or intersecting and may extend through the honeycomb body from a first end thereof to a second end thereof, which is opposite the first end.

[00134] A honeycomb body disclosed herein comprises a ceramic honeycomb structure comprising at least one wall supporting one or more particulate deposits for example which may be configured to filter particulate matter from a gas stream. The deposits can be in discrete regions or in some portions or some embodiments can form one or more layers of deposit material at a given location on the wall of the honeycomb body. The deposits according to some embodiments comprise inorganic material, in some embodiments organic material, and in some embodiments both inorganic material and organic material. For example, a honeycomb structure of a honeycomb body may, in one or more embodiments, be formed from cordierite or other porous ceramic material and further comprise material deposits disposed on or below wall surfaces of the cordierite honeycomb structure.

[00135] In one or more embodiments, the honeycomb body may be formed from cordierite, aluminum titanate, enstatite, mullite, forsterite, corundum (SiC), spinel, sapphirine, and periclase. In general, cordierite is a solid solution having a composition according to the formula (Mg,Fe)2Ah(Si5A10is). In embodiments, the pore size of the ceramic material may be controlled, the porosity of the ceramic material may be controlled, and the pore size distribution of the ceramic material may be controlled, for example by varying the particle sizes of the ceramic raw materials. In addition, pore formers may be included in ceramic batches used to form the honeycomb body.

[00136] In embodiments, walls of the honeycomb body may have an average thickness from greater than or equal to 25 pm to less than or equal to 250 pm, such as from greater than or equal to 45 pm to less than or equal to 230 pm, greater than or equal to 65 pm to less than or equal to 210 pm, greater than or equal to 65 pm to less than or equal to 190 pm, or greater than or equal to 85 pm to less than or equal to 170 pm. The walls of the honeycomb body can be described to have a base portion comprised of a bulk portion (also referred to herein as the bulk), and surface portions (also referred to herein as the surface). The surface portion of the walls extends from a surface of a wall of the honeycomb body into the wall toward the bulk portion of the honeycomb body. The surface portion may extend from 0 (zero) to a depth of about 10 pm into the base portion of the wall of the honeycomb body. In embodiments, the surface portion may extend about 5 pm, about 7 pm, or about 9 pm (/.< ., a depth of 0 (zero)) into the base portion of the wall. The bulk portion of the honeycomb body constitutes the thickness of wall minus the surface portions. Thus, the bulk portion of the honeycomb body may be determined by the following equation: [00137] ^total ~ ^surface

[00138] where ttotai is the total thickness of the wall and tsurface is the thickness of the wall surface.

[00139] In one or more embodiments, the bulk of the honeycomb body (prior to applying any material or filtration material or layer) has a bulk median pore size from greater than or equal to 7 pm to less than or equal to 25 pm, such as from greater than or equal to 12 pm to less than or equal to 22 pm, or from greater than or equal to 12 pm to less than or equal to 18 pm. For example, in embodiments, the bulk of the honeycomb body may have bulk median pore sizes of about 10 pm, about 11 pm, about 12 pm, about 13 pm, about 14 pm, about 15 pm, about 16 pm, about 17 pm, about 18 pm, about 19 pm, or about 20 pm. Generally, pore sizes of any given material exist in a statistical distribution. Thus, the term "median pore size" or "dso" (prior to applying any material or filtration material or layer) refers to a length measurement, above which the pore sizes of 50% of the pores lie and below which the pore sizes of the remaining 50% of the pores lie, based on the statistical distribution of all the pores. Pores in ceramic bodies can be manufactured by at least one of: (1) inorganic batch material particle size and size distributions; (2) furnace/heat treatment firing time and temperature schedules; (3) furnace atmosphere (e.g., low or high oxygen and/or water content), as well as; (4) pore formers, such as, for example, polymers and polymer particles, starches, wood flour, hollow inorganic particles and/or graphite/ carb on particles.

[00140] In specific embodiments, the median pore size (dso) of the bulk of the honeycomb body (prior to applying any material or filtration material or layer) is in a range of from 10 pm to about 16 pm, for example 13-14 pm, and the dio refers to a length measurement, above which the pore sizes of 90% of the pores lie and below which the pore sizes of the remaining 10% of the pores lie, based on the statistical distribution of all the pores is about 7 pm. In specific embodiments, the dw refers to a length measurement, above which the pore sizes of 10% of the pores of the bulk of the honeycomb body (prior to applying any material or filtration material or layer) lie and below which the pore sizes of the remaining 90% of the pores lie, based on the statistical distribution of all the pores is about 30 pm. micrometer [00141] In embodiments, the bulk of the honeycomb body may have bulk porosities, not counting a coating, of from greater than or equal to 50% to less than or equal to 75% as measured by mercury intrusion porosimetry. Other methods for measuring porosity include scanning electron microscopy (SEM) and X-ray tomography, these two methods in particular are valuable for measuring surface porosity and bulk porosity independent from one another. In one or more embodiments, the bulk porosity of the honeycomb body may be in a range of from about 50% to about 75%, in a range of from about 50% to about 70%, in a range of from about 50% to about 65%, in a range of from about 50% to about 60%, in a range of from about 60% to about 70%, for example.

[00142] In one or more embodiments, the surface portion of the honeycomb body has a surface median pore size from greater than or equal to 7 pm to less than or equal to 20 pm, such as from greater than or equal to 8 pm to less than or equal to 15 pm, or from greater than or equal to 10 pm to less than or equal to 14 pm. For example, in embodiments, the surface of the honeycomb body may have surface median pore sizes of about 8 pm, about 9 pm, about 10 pm, about 11 pm, about 12 pm, about 13 pm, about 14 pm, or about 15 pm.

[00143] In embodiments, the surface of the honeycomb body may have surface porosities, prior to application of a layer, of from greater than or equal to 35% to less than or equal to 75% as measured by mercury intrusion porosimetry, SEM, or X-ray tomography. In one or more embodiments, the surface porosity of the honeycomb body may be less than 65%, such as less than 60%, less than 55%, less than 50%, less than 48%, less than 46%, less than 44%, less than 42%, less than 40%, less than 48%, or less than 36% for example.

[00144] Referring now to FIGS. 8-9, a honeycomb body in the form of a particulate filter

200 is schematically depicted. The particulate filter 200 may be used as a wall-flow filter to filter particulate matter from an exhaust gas stream 250, such as an exhaust gas stream emitted from a gasoline engine, in which case the particulate filter 200 is a gasoline particulate filter. The particulate filter 200 generally comprises a honeycomb body having a plurality of channels

201 or cells which extend between an inlet end 202 and an outlet end 204, defining an overall length L_a (shown in FIG. 9). The channels 201 of the particulate filter 200 are formed by, and at least partially defined by a plurality of intersecting channel walls 206 that extend from the inlet end 202 to the outlet end 204. The particulate filter 200 may also include a skin layer 205 surrounding the plurality of channels 201. This skin layer 205 may be extruded during the formation of the channel walls 206 or formed in later processing as an after-applied skin layer, such as by applying a skinning cement to the outer peripheral portion of the channels.

[00145] In embodiments, certain channels are designated as inlet channels 208 and certain other channels are designated as outlet channels 210. In embodiments of the particulate filter 200, at least a first set of channels may be plugged with plugs 212. Generally, the plugs 212 are arranged proximate the ends (i.e., the inlet end or the outlet end) of the channels 201. The plugs are generally arranged in a pre-defined pattern, such as in the checkerboard pattern shown in FIG. 8, with every other channel being plugged at an end. The inlet channels 208 may be plugged at or near the outlet end 204, and the outlet channels 210 may be plugged at or near the inlet end 202 on channels not corresponding to the inlet channels, as depicted in FIG. 9. Accordingly, each cell may be plugged at or near one end of the particulate filter only. The intersecting channel walls 206 are porous such that the gas stream 250 flows through a thickness of the walls, as well as in an axial direction, and overall in a direction of the arrows, from inlet channels 208 to the outlet channels 210. The porous ceramic walls have an average wall thickness. A midpoint 206m is one-half of the average wall thickness.

[00146] Although FIG. 8 depicts a checkerboard plugging pattern, alternative plugging patterns may be used in the porous ceramic honeycomb article. In the embodiments described herein, the particulate filter 200 may be formed with a channel density of up to about 600 channels per square inch (cpsi). For example, in embodiments, the particulate filter 100 may have a channel density in a range from about 100 cpsi to about 600 cpsi. In some other embodiments, the particulate filter 100 may have a channel density in a range from about 100 cpsi to about 400 cpsi or even from about 200 cpsi to about 300 cpsi.

[00147] In the embodiments described herein, the channel walls 206 of the particulate filter 200 may have a thickness of greater than about 4 mils (101.6 micrometers). For example, in embodiments, the thickness of the channel walls 206 may be in a range from about 4 mils up to about 30 mils (762 micrometers). In some other embodiments, the thickness of the channel walls 206 may be in a range from about 7 mils (177.8 micrometers) to about 20 mils (508 micrometers).

[00148] In embodiments of the particulate filter 200 described herein the channel walls 206 of the particulate filter 200 may have a bare open porosity (i.e., the porosity before any coating is applied to the honeycomb body) % P^35% prior to the application of any coating to the particulate filter 200. In embodiments the bare open porosity of the channel walls 206 may be such that 40%^% P^75%. In other embodiments, the bare open porosity of the channel walls 206 may be such that 45%i% Pi75%, 50%i% Pi75%, 55%i% Pi75%, 60%i% Pi 75%, 45%i% Pi 70%, 50%i% Pi70%, 55%i% Pi70%, or 60%i% Pi70%.

[00149] Further, in embodiments, the channel walls 206 of the particulate filter 200 are formed such that the pore distribution in the channel walls 206 has a median pore size of i 30 micrometers prior to the application of any coatings (i.e., bare). For example, in embodiments, the median pore size may be

8 micrometers and less than or i 30 micrometers. In other embodiments, the median pore size may be

10 micrometers and less than or i 30 micrometers. In other embodiments, the median pore size may be

10 micrometers and less than or i 25 micrometers. In embodiments, particulate filters produced with a median pore size greater than about 30 micrometers have reduced filtration efficiency while with particulate filters produced with a median pore size less than about 8 micrometers may be difficult to infiltrate the pores with a washcoat containing a catalyst. Accordingly, in embodiments, it is desirable to maintain the median pore size of the channel wall in a range of from about 8 micrometers to about 30 micrometers, for example, in a range of rom 10 micrometers to about 20 micrometers. [00150] In one or more embodiments described herein, the honeycomb body of the particulate filter 200 is formed from a metal or ceramic material such as, for example, cordierite, silicon carbide, aluminum oxide, aluminum titanate or any other ceramic material suitable for use in elevated temperature particulate filtration applications. For example, the particulate filter 200 may be formed from cordierite by mixing a batch of ceramic precursor materials which may include constituent materials suitable for producing a ceramic article which predominately comprises a cordierite crystalline phase. In general, the constituent materials suitable for cordierite formation include a combination of inorganic components including talc, a silica-forming source, and an alumina-forming source. The batch composition may additionally comprise clay, such as, for example, kaolin clay. The cordierite precursor batch composition may also contain organic components, such as organic pore formers, which are added to the batch mixture to achieve the desired pore size distribution. For example, the batch composition may comprise a starch which is suitable for use as a pore former and/or other processing aids. Alternatively, the constituent materials may comprise one or more cordierite powders suitable for forming a sintered cordierite honeycomb structure upon firing as well as an organic pore former material.

[00151] In various embodiments the honeycomb body is configured to filter particulate matter from a gas stream, for example, an exhaust gas stream from a gasoline engine. Accordingly, the median pore size, porosity, geometry and other design aspects of both the bulk and the surface of the honeycomb body are selected taking into account these filtration requirements of the honeycomb body. As an example, and as shown in the embodiment of FIG. 10, a wall 310 of the honeycomb body 300, which can be in the form of the particulate filter as shown in FIGS. 8 and 9, has layer 320 disposed thereon, which in embodiments is sintered or otherwise bonded by heat treatment. The layer 320 may comprise particles 325 that are deposited on the wall 310 of the honeycomb body 300 and help prevent particulate matter from exiting the honeycomb body along with the gas stream 330, such as, for example, soot and ash, and to help prevent the particulate matter from clogging the base portion of the walls 310 of the honeycomb body 300. In this way, and according to embodiments, the layer 320 can serve as the primary filtration component while the base portion of the honeycomb body can be configured to otherwise minimize pressure drop for example as compared to conventional honeycomb bodies without such layer. As will be described in further detail herein, the layer may be formed by a suitable method, such as, for example, an aerosol deposition method. Aerosol deposition enables the formation of a thin, porous layer at least some surfaces of the walls of the honeycomb body. An advantage of the aerosol deposition method according to one or more embodiments is that honeycomb bodies can be produced more economically than in other techniques such as flame deposition processes. According to one or more embodiments, the aerosol deposition processes produce a unique primary particle morphology. [00152] In various embodiments, the inorganic material in the form of deposits is effective to filter particulate matter from a gas stream, for example, an exhaust gas stream from a gasoline engine. Accordingly, the median pore size, porosity, geometry and other design aspects of both the bulk and the surface of the honeycomb body are selected taking into account these filtration requirements of the honeycomb body. Particles of the inorganic material that are deposited on the wall of the honeycomb body and help prevent particulate matter, such as, for example, soot and ash, from exiting the honeycomb body and to help prevent the particulate matter from clogging the base portion of the walls of the honeycomb body. In this way, and according to embodiments, the inorganic deposits can serve as a primary filtration component while the porous ceramic walls of the honeycomb body can be configured to otherwise minimize pressure drop for example as compared to conventional honeycomb bodies without such layer. As will be described in further detail herein, the layer may be formed by a suitable method, such as, for example, an aerosol deposition method. Aerosol deposition enables the formation of a thin, porous layer at least some surfaces of the walls of the honeycomb body.

[00153] According to one or more embodiments, a process is provided which includes forming an aerosol with a binder process, which is deposited on a honeycomb body to provide a high filtration efficiency material, which may be an inorganic layer, on the honeycomb body to provide a gasoline particulate filter. According to one or more embodiments, the process can include the steps of mixture preparation, atomization, drying, and deposition of material on the walls of a wall flow filter and curing. Deposits of inorganic deposits having a high mechanical integrity can be formed without any sintering steps (e.g., heating to temperatures in excess of 1000 °C) by aerosol deposition with binder. [00154] According to one or more embodiments, an exemplary process flow 400 according to FIG. 10 for coating particles of an inorganic material on one or more portions of porous ceramic walls of a honeycomb body includes: mixture preparation 405, atomizing to form droplets 410, intermixing droplets and a gaseous carrier stream 415; evaporating liquid vehicle to form agglomerates 420, depositing of material, e.g., agglomerates, on the walls of a wall-flow filter 425, and optional post-treatment 430 to, for example, bind the material on, or in, or both on and in, the porous walls of the honeycomb body. Aerosol deposition methods form of agglomerates comprising a binder can provide a high mechanical integrity even without any high temperature curing steps (e.g., heating to temperatures in excess of 1000°C), and in embodiments even higher mechanical integrity after a curing step such as a high temperature (e.g., heating to temperatures in excess of 1000°C) curing step.

[00155] Inorganic particles may be supplied as a raw material suspended in a liquid vehicle to which a further liquid vehicle is optionally added.

[00156] In embodiments, the suspension is aqueous-based, and in other embodiments, the suspension is organic-based, for example, an alcohol such as ethanol or methanol.

[00157] The solution is formed using a solvent which is added to dilute the suspension if needed. Decreasing the solids content in the solution could reduce the aggregate size proportionally if the droplet generated by atomizing has similar size. The solvent should be miscible with suspension mentioned above, and be a solvent for binder and other ingredients.

[00158] A binder is optionally added to reinforce the material, which comprise inorganic binder, to provide mechanical integrity to deposited material. The binder provides binding strength between particles at elevated temperature (>500° C). The starting material can be organic. After exposure to high temperature in excess of about 150 °C, the organic will decompose or react with moisture and oxygen in the air. Suitable binders include but are not limited to alkoxy-siloxane resins. In one or more embodiments, the alkoxy-siloxane resins are reactive during processing. An exemplary reactive alkoxy-siloxane resin (methoxy functional) prior to processing has a specific gravity of 1.1 at 25°C. Another exemplary reactive alkoxysiloxane resin (methyl-methoxy functional) prior to processing has a specific gravity of 1.155 at 25°C. [00159] Catalyst can be added to accelerate the cure reaction of binder. A catalyst that can be used to accelerate the cure reaction of reactive alkoxy-siloxane resins is titanium butoxide.

[00160] The mixture is atomized into fine droplets by high pressure gas through a nozzle. The atomizing gas can contribute to breaking up the liquid-particulate-binder stream into the droplets. The droplet size can be adjusted by adjusting the surface tension of the solution, viscosity of the solution, density of the solution, gas flow rate, gas pressure, liquid flow rate, liquid pressure, and nozzle design. In one or more embodiments, the atomizing gas comprises air, nitrogen or mixture thereof. In specific embodiments, the atomizing gas and the apparatus does not comprise air.

[00161] The droplets are conveyed toward the honeycomb body by a gaseous carrier stream. In one or more embodiments, the gaseous carrier stream comprises a carrier gas and the atomizing gas. In one or more embodiments, at least a portion of the carrier gas contacts the atomizing nozzle. In one or more embodiments, substantially all of the liquid vehicle is evaporated from the droplets to form agglomerates comprised of the particles and the binder material.

[00162] In one or more embodiments, the gaseous carrier stream is heated prior to being mixed with the droplets. In one or more embodiments, the gaseous carrier stream is at a temperature in the range of from greater than or equal to 50°C to less than or equal to 500°C, including all greater than or equal to 80°C to less than or equal to 300°C, greater than or equal to 50°C to less than or equal to 150°C, and all values and subranges therebetween. Operationally, temperature can be chosen to at least evaporate solvent of the mixture or suspension so long as the final temperature is above the dew point. As non-limiting example, ethanol can be evaporated at a low temperature. Without being held to theory, it is believed that an advantage of a higher temperature is that the droplets evaporate faster and when the liquid is largely evaporated, they are less likely to stick when they collide. In certain embodiments, smaller agglomerates contribute to better filtration material deposits formation. Furthermore, it is believed that if droplets collide but contain only a small amount of liquid (such as only internally), the droplets may not coalesce to a spherical shape. In embodiments, non-spherical agglomerates may provide desirable filtration performance. [00163] Preferably the droplets are dried in an evaporation section of the apparatus, forming dry solid agglomerates, which may be referred to as "microparticles" which are comprised of fumed silica and binder-type material. The liquid vehicle, or solvent, is evaporated and passes through the honeycomb body in a gaseous or vapor phase so that liquid solvent residual or condensation is minimized during material deposition. When the agglomerate is carried into the honeycomb body by gas flow, the residual liquid in the inorganic material should be less than 10 wt%. All liquid is preferably evaporated as a result of the drying and are converted into a gas or vapor phase. The liquid residual could include solvent in the mixture (such as ethanol in the examples), or water condensed from the gas phase. Binder is not considered as liquid residual, even if some or all of the binder may be in liquid or otherwise non-solid state before cure.

[00164] The fumed silica particles/agglomerates are carried in gas flow, and the fumed silica particles or agglomerates, and/or aggregates thereof, are deposited on inlet wall surfaces of the honeycomb body when the gas passes through the honeycomb body. In one or more embodiments, the fumed silica agglomerates and/or aggregates thereof are deposited onto the porous walls of the plugged honeycomb body. The deposited fumed silica may be disposed on, or in, or both on and in, the porous walls. In one or more embodiments, the plugged honeycomb body comprises inlet channels which are plugged at a distal end of the honeycomb body, and outlet channels which are plugged at a proximal end of the honeycomb body. In one or more embodiments, the fumed silica particles are deposited on, or in, or both on and in, the walls defining the inlet channels.

[00165] The flow can be driven by a fan, a blower or a vacuum pump. Additional air can be drawn into the system to achieve a desired flow rate.

[00166] In one or more embodiments, the average diameter of the fumed silica agglomerates is in a range of from 300 nm to 10 micrometers, 300 nm to 8 micrometers, 300 nm to 7 micrometers, 300 nm to 6 micrometers, 300 nm micrometer to 5 micrometers, 300 nm micrometer to 4 micrometers, or 300 nm to 3 micrometers. In specific embodiments, the average diameter of the agglomerates is in the range of 0.4 micrometers to 2 micrometers, including about 1 micrometer. The average diameter of the agglomerates can be measured by a scanning electron microscope. [00167] In one or more embodiments, the average diameter of the fumed silica agglomerates is in a range of from 300 nm to 10 micrometers, 300 nm to 8 micrometers, 300 nm to 7 micrometers, 300 nm to 6 micrometers, 300 nm to 5 micrometers, 300 nm to 4 micrometers, or 300 nm to 3 micrometers, including the range of 1.5 micrometers to 3 micrometers, and including about 2 micrometers.

[00168] In one or more embodiments, the depositing of the fumed silica agglomerates onto the porous walls further comprises passing the gaseous carrier stream through the porous walls of the honeycomb body, wherein the walls of the honeycomb body filter out at least some of the agglomerates by trapping the filtered agglomerates on or in the walls of the honeycomb body. In one or more embodiments, the depositing of the fumed silica agglomerates onto the porous walls comprises filtering the agglomerates from the gaseous carrier stream with the porous walls of the plugged honeycomb body.

[00169] A post-treatment may optionally be used to adhere the fumed silica agglomerates to the honeycomb body, and/or to each other. That is, in one or more embodiments, at least some of the agglomerates adhere to the porous walls. In one or more embodiments, the post-treatment comprises heating and/or curing the binder when present according to one or more embodiments. In one or more embodiments, the binder material causes the agglomerates to adhere or stick to the walls of the honeycomb body. In one or more embodiments, the binder material tackifies the agglomerates.

[00170] Depending on the binder composition, the curing conditions are varied. According to embodiments, a low temperature cure reaction is utilized, for example, at a temperature of < 100°C. In embodiments, the curing can be completed in the vehicle exhaust gas with a temperature < 950° C. A calcination treatment is optional, which can be performed at a temperature <650° C. Exemplary curing conditions are: a temperature range of from 40 °C to 200 °C for 10 minutes to 48 hours.

[00171] As mentioned above, the filtration enhancing material, which may be an inorganic layer, on walls of the honeycomb body is in various embodiments very thin compared to thickness of the base portion of the walls of the honeycomb body. In embodiments, the average thickness of the material, which may be an inorganic layer, on the base portion of the walls of the honeycomb body is greater than or equal to 0.1 pm and less than or equal to 50 qm, or greater than or equal to 0.5 qm and less than or equal to 45 qm, greater than or equal to 0.5 qm and less than or equal to 40 qm, or greater than or equal to 0.5 qm and less than or equal to 35 qm, or greater than or equal to 0.5 qm and less than or equal to 30 qm, greater than or equal to 0.5 qm and less than or equal to 25 qm, or greater than or equal to 0.5 qm and less than or equal to 20 qm, or greater than or equal to 0.5 qm and less than or equal to 15 qm, greater than or equal to 0.5 qm and less than or equal to 10 qm.

[00172] As discussed above, the material, which may be an inorganic layer, can be applied to the walls of the honeycomb body by methods that permit the inorganic material, which may be an inorganic layer, to have a small median pore size. This small median pore size allows the material, which may be an inorganic layer, to filter a high percentage of particulate and prevents particulate from penetrating honeycomb and settling into the pores of the honeycomb. The small median pore size of material, which may be an inorganic layer, according to embodiments increases the filtration efficiency of the honeycomb body. In one or more embodiments, the material, which may be an inorganic layer, on the walls of the honeycomb body has a median pore size from greater than or equal to 0.1 pm to less than or equal to 5 pm, such as from greater than or equal to 0.5 qm to less than or equal to 4 qm, or from greater than or equal to 0.6 qm to less than or equal to 3 qm. For example, in embodiments, the material, which may be an inorganic layer, on the walls of the honeycomb body may have median pore sizes of about 0.5 qm, about 0.6 qm, about 0.7 qm, about 0.8 qm, about 0.9 qm, about 1 qm, about 2 qm, about 3 qm, or about 4 qm.

[00173] As stated above, and without being bound by any particular theory, it is believed that a low pressure drop is achieved by honeycomb bodies of embodiments because the material, which may be an inorganic layer, on the honeycomb body is a primary filtration component of the honeycomb body, which allows for more flexibility in designing a honeycomb body. The selection of a honeycomb body having a low pressure drop in combination with the low thickness and porosity of the layer on the honeycomb body according to embodiments allows a honeycomb body of embodiments to have a low pressure drop when compared to conventional honeycomb bodies. In embodiments, a loading of the inorganic deposits is between 0.3 to 30 g/L on the honeycomb body, such as between 1 to 30 g/L on the honeycomb body, or between 3 to 30 g/L on the honeycomb body. In other embodiments, the layer is between 1 to 20 g/1 on the honeycomb body, such as between 1 to 10 g/1 on the honeycomb body. In specific embodiments, the loading of the inorganic material is in a range of from 1 to 9 g/L, 1 to 8 g/L, 1 to 7 g/L, 1 to 8 g/L, 1 to 5 g/L, 1 to 4 g/L, 1 to 3 g/L, 2 to 10 g/L, 2 to 9 g/L, 2 to 8 g/L, 2 to 7 g/L, 2 to 6 g/L, 2 to 5 g/L, 2 to 4 g/L, 3 to 10 g/L, 3 to 9 g/L, 3 to 8 g/L, 3 to 7 g/L, 3 to 6 g/L, 3 to 5 g/L, 4 to 10 g/L, 4 to 9 g/L 4 to 8 g/L, 4 to 7 g/L, or 4 to 6 g/L on the honeycomb body. Loading of the inorganic material is weight of added material in grams divided by the geometric part volume in liters. The geometric part volume is based on outer dimensions of the honeycomb filter body (or plugged honeycomb body). In embodiments, the pressure drop (i.e., a clean pressure drop without soot or ash) across the honeycomb body compared to a honeycomb without a thin porous inorganic material, which may be an inorganic layer, is less than or equal to 20%, such as less than or equal to 9%, or less than or equal to 8%. In other embodiments, the pressure drop across the honeycomb body is less than or equal to 7%, such as less than or equal to 6%. In still other embodiments, the pressure drop across the honeycomb body is less than or equal to 5%, such as less than or equal to 4%, or less than or equal to 3%.

[00174] As stated above, and without being bound to any particular theory, small pore sizes in the layer on the walls of the honeycomb body allow the honeycomb body to have good filtration efficiency even before ash or soot build-up occurs in the honeycomb body. The filtration efficiency of honeycomb bodies may be measured using the protocol outlined in Tandon et al., 65 CHEMICAL ENGINEERING SCIENCE 4751-60 (2010). As used herein, the initial filtration efficiency of a honeycomb body refers to a new or regenerated honeycomb body that does not comprise any measurable soot loading. In embodiments, the initial filtration efficiency (i.e., clean filtration efficiency) of the honeycomb body is greater than or equal to 70%, such as greater than or equal to 80%, or greater than or equal to 85%. In yet other embodiments, the initial filtration efficiency of the honeycomb body is greater than 90%, such as greater than or equal to 93%, or greater than or equal to 95%, or greater than or equal to 98% or greater than or equal to 99.0%.

[00175] The material, which may be an inorganic layer, on the walls of the honeycomb body according to embodiments is thin and has a porosity, and in embodiments the layer on walls of the honeycomb body also has good chemical durability and physical stability. The chemical durability and physical stability of the material, which may be an inorganic layer, on the honeycomb body can be determined, in embodiments, by subjecting the honeycomb body to test cycles comprising bum out cycles and an aging test and measuring the initial filtration efficiency before and after the test cycles. For instance, one exemplary method for measuring the chemical durability and the physical stability of the honeycomb body comprises measuring the initial filtration efficiency of a honeycomb body; loading soot onto the honeycomb body under simulated operating conditions; burning out the built up soot at about 650 °C; subjecting the honeycomb body to an aging test at 1050 °C and 10% humidity for 12 hours; and measuring the filtration efficiency of the honeycomb body. Multiple soot build up and burnout cycles may be conducted. A small change in filtration efficiency (AFE) from before the test cycles to after the test cycles indicates better chemical durability and physical stability of the material, which may be an inorganic layer, on the honeycomb body. In embodiments, the AFE is less than or equal to 5%, such as less than or equal to 4%, or less than or equal to 3%. In other embodiments, the AFE is less than or equal to 2%, or less than or equal to 1%.

[00176] In embodiments, the material, which may be an inorganic layer, on the walls of the honeycomb body comprises fumed silica, and in one or more embodiments consists essentially of fumed silica, and in other embodiments may be further comprised of one or a mixture of ceramic components, such as, for example, ceramic components selected from the group consisting of (non-fumed) SiCh, AI2O3, MgO, ZrCh, CaO, TiCh, CeCh, Na2O, Pt, Pd, Ag, Cu, Fe, Ni, and mixtures thereof. Thus, the material, which may be an inorganic layer, on the walls of the honeycomb body may comprise an oxide ceramic. In embodiments, the material, which may be an inorganic layer, on the walls of the honeycomb body may further comprise cordierite, aluminum titanate, enstatite, mullite, forsterite, corundum (SiC), spinel, sapphirine, and periclase.

[00177] In embodiments, the method of forming a honeycomb body comprises forming or obtaining an aerosol that comprises fumed silica particles.

[00178] In one or more embodiments, the aerosol, which is well-dispersed in a carrier fluid, is directed to a honeycomb body, and the aerosol particles are deposited on the honeycomb body. In embodiments, the honeycomb body may have one or more of the channels plugged on one end, such as, for example, the first end 105 of the honeycomb body during the deposition of the aerosol to the honeycomb body. The plugged channels may, in embodiments, be removed after deposition of the aerosol particles. But, in other embodiments, the channels may remain plugged even after deposition. The pattern of plugging channels of the honeycomb body is not limited, and in embodiments all the channels of the honeycomb body may be plugged at one end. In other embodiments, only a portion of the channels of the honeycomb body may be plugged at one end. In such embodiments, the pattern of plugged and unplugged channels at one end of the honeycomb body is not limited and may be, for example, a checkerboard pattern where alternating channels of one end of the honeycomb body are plugged. By plugging all or a portion of the channels at one end of the honeycomb body during deposition of the aerosol, the contents of the aerosol flow may be evenly distributed within the channels 110 of the honeycomb body 100.

[00179] Embodiments of honeycomb bodies and methods for forming the same as disclosed and described herein are now provided.

[00180] According to one or more embodiments, binders with high temperature (e.g., greater than 400° C) resistance are included in the inorganic deposits, which may be an inorganic layer, to enhance integrity of the material at high temperatures encountered in automobile exhaust gas emissions treatment systems. In embodiments, the binder material is present at a loading of 5 to 60 %, in some of these embodiments 10 to 60 %, in some of these embodiments 10 to 29 %, and in some of these embodiments 30 to 60 %, by weight of the inorganic material in the particles. In some of these embodiments, the inorganic deposits comprise a binder in an amount of 5 to 50 wt%. In one or more embodiments, the binder is an alkoxy-siloxane resin. According to one or more embodiments, other potential inorganic and organic binders such as silicate (e.g. ISfeSiCh), phosphate (e.g. AIPO4, AlEkCPO^), hydraulic cement (e.g. calcium aluminate), sol (e.g. mSiCh nEEO, A1(OH)_X (H2O)e-_x) and metal alkoxides, could also be utilized in the inorganic deposits to increase mechanical strength by an appropriate curing process.

EXAMPLES

[00181] Embodiments will be further understood by the following non-limiting examples. [00182] Pressure drop (dP) of various plugged honeycomb bodies was measured by a rig, which allows a controlled amount of air flow across a test article. A difference in pressure as measured by an upstream senor as compared to a downstream sensor is the reported pressure drop. In a typical measurement, an article is cleaned with compressed air and loaded in the rig. An air flowrate of 210 SCFM (standard ft³/min) was used, with the standard condition defined at 21.1°C and 1 ATM.

[00183] A pressure drop measurement without any soot is called clean dP or clean pressure drop, and is referred to as “dPO”. A pressure drop measured with soot is called soot loaded dP or soot loaded pressure drop, and is referred to as “SLdP”. To load a test article with soot, the test article is loaded with an amount of soot in a separate apparatus. Artificial soot is deposited into the test article using compressed nitrogen (N2) as a carrier gas. Each apparatus has a designated soot feeder which is connected to a funnel. Once soot is delivered to the funnel by an auger screw, it is pulled into the main exhaust pipe by a venture system. Incremental soot loads are generated in the test article with corresponding weight and pressure drop measured at each level to generate the SLdP profile. The flowrate of nitrogen used to load the soot in the data reported here is 16 ft³/min.

[00184] Filtration efficiency (FE) of various plugged honeycomb bodies was measured as follows.

[00185] It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Thus, it is intended that the specification cover the modifications and variations of the various embodiments described herein provided such modification and variations come within the scope of the appended claims and their equivalents.

Claims

What is claimed is:

1. A method for making a filtration article, the method comprising: depositing particles comprised of inorganic material comprising fumed silica particles onto porous cell walls inside a honeycomb structure of a filter body, the cell walls defining a plurality of axial channels, wherein a first subset of channels is sealed at a first end and second subset of channels is sealed at a second end opposite the first end.

2. The method of Claim 1 wherein the fumed silica particles are deposited as aggregates of fumed silica primary particles, the primary particles having a particle size of 5 nm to 250 nm.

3. The method of Claim 1 wherein the fumed silica particles are deposited as aggregates of fumed silica primary particles, the primary particles having a particle size of 5 nm to 150 nm.

4. The method of Claim 1 wherein the primary particles have a BET surface area of 5 to 500 m²/g.

5. The method of Claim 4 wherein the BET surface area is in a range of 10 to 400 m²/g.

6. The method of Claim 4 wherein g the BET surface area in a range of 20 to 400 m²/g.

7. The method of Claim 1 wherein the fumed silica particles are deposited as aggregates of fumed silica primary particles, the primary particles having a BET surface area of 5 to 500 m²/g.

8. The method of Claim 7 wherein the fumed silica particles are deposited as aggregates of fumed silica primary particles, the primary particles having a BET surface area of 10 to 400 m²/g.

9. The method of Claim 8 wherein the fumed silica particles are deposited as aggregates of fumed silica primary particles, the primary particles having a BET surface area of 23 m²/g to 380 m²/g.

10. The method of Claim 1 wherein the fumed silica particles are deposited as aggregates of fumed silica primary particles, the primary particles having a particle size of 7 nm to 124 nm.

11. The method of Claim 1 wherein the particles further comprise a binder material.

12. The method of Claim 11 wherein the binder material is present at a loading of 10 to 60 % by weight of the inorganic material in the particles.

13. The method of Claim 11 wherein the binder material is present at a loading of 10 to 29 % by weight of the inorganic material in the particles.

14. The method of Claim 1 wherein the binder material is present at a loading of 30 to 60 % by weight of the inorganic material in the particles.

15. The method of Claim 1 further comprising heating the filter body sufficient to cause the binder to fuse at least some of the particles to each other, to the porous cell walls, or both.

16. The method of Claim 1 wherein less than or equal to 3.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 90%.

17. The method of Claim 1 wherein less than or equal to 2.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 90%.

18. The method of Claim 1 wherein less than or equal to 1.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 90%.

19. The method of Claim 1 wherein less than or equal to 0.5 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 90%.

20. The method of Claim 1 wherein 0.5 to 3.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 90%.

21. The method of Claim 1 wherein 0.5 to 2.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 90%.

22. The method of Claim 1 wherein 0.5 to 1.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 90%.

23. The method of Claim 1 wherein less than or equal to 0.5 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 90%.

24. The method of Claim 1 wherein less than or equal to 4.5 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 95%.

25. The method of Claim 1 wherein less than or equal to 4.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 95%.

26. The method of Claim 1 wherein less than or equal to 3.5 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 95%.

27. The method of Claim 1 wherein less than or equal to 3.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 95%.

28. The method of Claim 1 wherein less than or equal to 2.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 95%.

29. The method of Claim 1 wherein less than or equal to 1.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 95%.

30. The method of Claim 1 wherein 0.75 to 4.5 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 95%.

31. The method of Claim 1 wherein 0.75 to 4.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 95%.

32. The method of Claim 1 wherein 0.75 to 3.5 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 95%.

33. The method of Claim 1 wherein 0.75 to 3.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 95%.

34. The method of Claim 1 wherein 0.75 to 2.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 95%.

35. The method of Claim 1 wherein less than or equal to 6.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 98%.

36. The method of Claim 1 wherein less than or equal to 5.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 98%.

37. The method of Claim 1 wherein less than or equal to 4.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 98%.

38. The method of Claim 1 wherein less than or equal to 3.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 98%.

39. The method of Claim 1 wherein less than or equal to 2.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 98%.

40. The method of Claim 1 wherein less than or equal to 2.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 98%.

41. The method of Claim 1 wherein 1.0 to 6.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 98%.

42. The method of Claim 1 wherein 1.0 to 5.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 98%.

43. The method of Claim 1 wherein 1.0 to 4.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 98%.

44. The method of Claim 1 wherein 1.0 to 3.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 98%.

45. The method of Claim 1 wherein 1.0 to 2.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 98%.

46. The method of Claim 1 wherein less than 8.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 99.0%.

47. The method of Claim 1 wherein less than or equal to 7.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 99.0%.

48. The method of Claim 1 wherein less than or equal to 6.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 99.0%.

49. The method of Claim 1 wherein less than or equal to 5.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 99.0%.

50. The method of Claim 1 wherein less than or equal to 4.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 99.0%.

51. The method of Claim 1 wherein less than or equal to 3.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 99.0%.

52. The method of Claim 1 wherein 2.0 to 8.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 99.0%.

53. The method of Claim 1 wherein 2.0 to 7.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 99.0%.

54. The method of Claim 1 wherein 5.0 to 7.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 99.0%.

55. The method of Claim 1 wherein 7.0 to 8.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 99.0%.

56. The method of Claim 1 wherein 2.0 to 3.0 grams of fumed silica per liter of filtration article is present in the honeycomb structure, and the filtration article exhibits a clean filtration efficiency of greater than or equal to 99.0%.

57. A filtration article comprising: a plugged honeycomb filter body comprising intersecting porous ceramic walls defining a plurality of channels comprised of inlet channels, which are plugged at a distal end of the plugged honeycomb filter body, and outlet channels, which are plugged at a proximal end of the plugged honeycomb filter body, wherein the porous ceramic walls comprise a plurality of pores, wherein some of the pores extend to surfaces of the walls which define the inlet channels; and fumed silica deposits disposed on surfaces of the walls which define the inlet channels of the plugged honeycomb filter body.

58. The filtration article of claim 57 wherein the inorganic deposits extend over a majority of the pores that extend to the surface of the walls.

59. The filtration article of claim 57 wherein the inorganic deposits extend over all of the pores that extend to the surface of the walls.

60. The filtration article of claim 57 wherein some of the inorganic deposits penetrate into the walls to a penetration depth of less than 1/10 of an average thickness of the wall.

61. The filtration article of claim 57 wherein some of the inorganic deposits penetrate into the walls to a penetration depth of 1/1000 to 1/10 of an average thickness of the wall.

62. A filtration article comprising: a plugged honeycomb filter body comprising: porous ceramic walls; channels which are plugged at a distal end of the plugged honeycomb filter body; and channels which are plugged at a proximal end of the plugged honeycomb filter body; inorganic deposits comprising fumed silica disposed on walls defining a subset of channels of the plugged honeycomb filter body

63. The filtration article of claim 62 wherein the inorganic deposits are positioned on the walls to a wall depth of less than or equal to 40 micrometers.

64. The filtration article of claim 62 wherein a loading of the inorganic deposits disposed within the plugged honeycomb filter body is less than or equal to 20 grams of the inorganic deposits per liter of the plugged honeycomb filter body.

65. The filtration article of claim 62 wherein the inorganic deposits comprise a median pore size in a range of greater than or equal to 0.1 micrometers to less than or equal to 5 micrometers.

66. The filtration article of claim 62 wherein the porous ceramic walls comprise a porosity of greater than or equal to 40% to less than or equal to 70%.

67. The filtration article of claim 62 wherein the inorganic deposits are comprised of nanoparticles present in the form of agglomerates.

68. A filtration article comprising: a plugged honeycomb filter body comprising: porous ceramic walls; channels which are plugged at a distal end of the plugged honeycomb filter body; and channels which are plugged at a proximal end of the plugged honeycomb filter body; inorganic deposits comprising fumed silica particles disposed on walls defining a first subset of channels of the plugged honeycomb filter body at a loading of less than or equal to 20 grams of the inorganic deposits per liter of the plugged honeycomb filter body; wherein a clean filtration efficiency of the filtration article is greater than or equal to 90% as measured by a clean filtration efficiency test.

69. The filtration article of claim 68 wherein a loading of the inorganic deposits disposed within the plugged honeycomb filter body is less than or equal to 20 grams of the inorganic deposits per liter of the plugged honeycomb filter body.

70. The filtration article of claim 68 wherein the inorganic deposits comprise a median pore size in a range of greater than or equal to 0.1 micrometers to less than or equal to 5 micrometers.

71. The filtration article of claim 68 wherein the porous ceramic walls comprise a porosity of greater than or equal to 40% to less than or equal to 70%.

72. The filtration article of claim 68 wherein the inorganic deposits are comprised of nanoparticles present in the form of agglomerates.