Sorbent materials for reducing hydrocarbon bleed emissions in evaporative emission control systems - Patents.com

Abstract

A hydrocarbon adsorbent and an evaporative emission control system incorporating the same are disclosed in certain embodiments for reducing hydrocarbon bleed emissions from a fuel system. In one embodiment, the hydrocarbon adsorbent structure comprises a zeolite having a silica-to-alumina ratio of at least 20.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority to U.S. Provisional Patent Application No. 62 / 836,121, filed April 19, 2019, the disclosure of which is incorporated herein by reference in its entirety.

[0002] The present disclosure relates generally to hydrocarbon emission control systems, devices, and compositions for use therein. More specifically, the present disclosure relates to substrates coated with a hydrocarbon adsorbing coating composition, evaporative emission control system components, and evaporative emission control systems for controlling evaporative emissions of hydrocarbons from automotive vehicle engines and fuel systems. [Background technology]

[0003] Evaporative losses of gasoline fuel from the fuel systems of motor vehicles powered by internal combustion engines are the primary potential source of hydrocarbon air pollution. Evaporative emissions are defined as emissions that do not originate from the vehicle's exhaust system. The primary source of a vehicle's overall evaporative emissions are hydrocarbon fuel vapors that originate from the fuel system and the intake system. Canister systems that use activated carbon to adsorb fuel vapors emitted from the fuel system are used to limit such evaporative emissions. Currently, all vehicles have a fuel vapor canister to control evaporative emissions. Activated carbon is the standard sorbent material used in automotive evaporative emission control technology, which typically utilize activated carbon as the sorbent material to temporarily adsorb hydrocarbons.

[0004] Many fuel vapor canisters also include an additional control device to capture fuel vapors that escape from the carbon bed during the hot side of the diurnal temperature cycle. Current control devices for such emissions include only a carbon-containing honeycomb sorbent, for pressure drop reasons. In such systems, the adsorbed fuel vapors are periodically removed from the activated carbon by purging the canister system with fresh ambient air and desorbing the fuel vapors from the activated carbon, thereby regenerating the carbon for further adsorption of fuel vapors.

[0005] The establishment of strict regulations regarding allowable amounts of hydrocarbon emissions requires increasingly strict controls on hydrocarbon emissions from motor vehicles, even during periods of non-use. During such periods (i.e., when parked), the vehicle's fuel system may be exposed to a warm environment, which may result in increased vapor pressure within the fuel tank and, as a result, fuel may be lost through evaporation to the atmosphere.

[0006] The aforementioned canister systems have certain limitations with respect to capacity and performance. For example, the purge air does not desorb all of the fuel vapors adsorbed in the sorbent volume, resulting in residual hydrocarbons ("heel") that can be vented to the atmosphere. As used herein, the term "heel" refers to residual hydrocarbons that are typically present on the sorbent material when the canister is in a purged or "clean" state, which can result in a reduction in the adsorption capacity of the sorbent.

[0007] Bleed emissions, on the other hand, refer to emissions that escape from the sorbent material. Bleeding can occur, for example, when the equilibrium between adsorption and desorption significantly favors desorption over adsorption. Such emissions can occur when a vehicle is exposed to diurnal temperature changes over a period of several days, and are commonly referred to as "diurnal breathing losses." Certain regulations require that these diurnal breathing loss (DBL) emissions from canister systems be kept at very low levels. For example, as of March 22, 2012, California's Low Emission Vehicle Regulation (LEV-III) requires that for 2001 and newer model motor vehicles, canister DBL emissions not exceed 20 mg per the Bleed Emissions Test Procedure (BETP).

[0008] Stricter regulations regarding DBL emissions continue to spur the development of improved evaporative emission control systems, especially for use in vehicles with reduced purge volumes (i.e., hybrid vehicles). Such vehicles may otherwise generate high DBL emissions due to less frequent purging, which equates to lower total purge volumes and higher residual hydrocarbon heels. It is therefore desirable to have an evaporative emission control system that has low DBL emissions despite low volume and / or less frequent purge cycles. Additionally, there is a need for highly efficient evaporative emission control systems to reduce required space and weight while further reducing potential evaporative emissions under a variety of conditions. Summary of the Invention

[0009] The following presents a simplified summary of various aspects of the present disclosure to provide a basic understanding of such aspects. This summary is not an extensive overview of the disclosure. It is not intended to identify key or critical elements of the disclosure, nor to delineate the full scope of particular embodiments of the disclosure or the full scope of the claims. Its sole purpose is to present some concepts of the disclosure in a simplified form as a prelude to the more detailed description that is presented later.

[0010] In one aspect of the disclosure, a hydrocarbon adsorbent structure (e.g., that may be adapted to reduce evaporative emissions in a vehicle) includes a zeolite having a silica to alumina ratio of at least 20. The repeatable TGA butane adsorption of the zeolite is greater than 2 wt.%.

[0011] In some embodiments, the silica to alumina ratio is at least 30, at least 50, at least 100, at least 150, at least 200, at least 250, at least 300, at least 350, at least 400, at least 450, or at least 500. In some embodiments, the silica to alumina ratio ranges from 20 to 600. In some embodiments, the repeatable TGA butane adsorption of the zeolite is greater than 3 wt%, greater than 4 wt%, or greater than 5 wt%. In some embodiments, the average pore width of the micropores of the zeolite is less than 20 Å. In some embodiments, the average pore width of the zeolite is between 2.0 and 6.7 Å. In some embodiments, the zeolite is in a form characterized by an average d90 particle size of about 5 micrometers to about 50 micrometers, about 10 micrometers to about 25 micrometers, or about 15 micrometers to about 20 micrometers.

[0012] In some embodiments, the zeolite comprises a zeolite selected from the group consisting of AEI, BEA, BEC, CHA, EMT, FAU, FER, MFI, and combinations thereof. In some embodiments, the zeolite comprises a BEA zeolite. In some embodiments, the zeolite comprises an MFI zeolite.

[0013] In some embodiments, the hydrocarbon adsorbent structure comprises a substrate and a hydrocarbon adsorbent coating formed thereon, the hydrocarbon adsorbent coating comprising a zeolite. In some embodiments, the substrate comprises a ceramic monolith. In some embodiments, the loading of the hydrocarbon adsorbent coating on the substrate is about 0.5 g / in 3 ~ approx. 2.0g / in 3 , 0.5g / in 3~Approx. 1g / in 3 , or about 1 g / in 3 ~about 2g / in 3 In some embodiments, the thickness of the hydrocarbon adsorbent coating is less than about 500 micrometers. In some embodiments, the hydrocarbon adsorbent coating comprises a binder. In some embodiments, the binder comprises a styrene / acrylic copolymer. In some embodiments, the binder is present in an amount of about 5% to about 50% by weight, about 5% to about 30% by weight, or about 5% to about 15% by weight, based on the total weight of the hydrocarbon adsorbent coating. In some embodiments, the hydrocarbon adsorbent coating further comprises activated carbon.

[0014] In some embodiments, the hydrocarbon adsorbent structure is in the form of a monolithic body, with at least 50%, at least 60%, at least 70%, at least 80%, or at least 90% of the zeolite forming the monolithic body.

[0015] In another aspect of the disclosure, a bleed exhaust scrubber (e.g., which may be adapted for use in an evaporative emission control canister system) comprises adsorbent volumes, at least one of the adsorbent volumes comprising at least one hydrocarbon adsorbent structure described herein.

[0016] In another aspect of the disclosure, an air intake system (eg, which may be adapted to reduce evaporative emissions within a vehicle) comprises at least one hydrocarbon adsorbent structure described herein.

[0017] In another aspect of the disclosure, a cabin air purification system (eg, which may be adapted to reduce evaporative emissions within a vehicle) comprises at least one hydrocarbon adsorbent structure described herein.

[0018] In another aspect of the disclosure, an evaporative emission control canister comprises one or more sorbent volumes disposed within or external to the evaporative emission control canister and at least one bleed discharge scrubber contained within and fluidly coupled to the sorbent volume of the evaporative emission control canister, each bleed discharge scrubber comprising at least one hydrocarbon sorbent structure described herein. In some embodiments, the evaporative emission control canister comprises a plurality of bleed discharge scrubbers, each of which comprises at least one hydrocarbon sorbent structure described herein. One or more of the bleed discharge scrubbers may be contained within a respective sorbent volume of the evaporative emission control canister. In some embodiments, each of the plurality of bleed discharge scrubbers is fluidly arranged with other bleed discharge scrubbers or other sorbent volumes within the evaporative emission control canister in a series configuration, a parallel configuration, or a combination thereof. In some embodiments, the one or more bleed discharge scrubbers are adapted for use with or incorporated into an evaporative emission control canister system having a canister volume of 3.5 L or less, 3.0 L or less, 2.5 L or less, or 2.0 L or less. In some embodiments, the volume of the bleed discharge scrubber or the hydrocarbon adsorbent structure is less than 4 dL. In some embodiments, at least a portion of the micropores of the zeolite exhibit a pore volume of greater than 0.01 mL / g.

[0019] In another aspect of the disclosure, an evaporative emission control system includes a fuel tank for storing fuel, an engine adapted to receive and consume fuel from the fuel tank, and an evaporative emission control canister system fluidly coupled to the engine, the evaporative emission control canister system including at least one bleed exhaust scrubber fluidly coupled to the evaporative emission control, the at least one bleed exhaust scrubber including a sorbent volume, the sorbent volume including at least one hydrocarbon sorbent structure described herein. In some embodiments, the evaporative emission control system further includes a plurality of bleed exhaust scrubbers, each of the plurality of bleed exhaust scrubbers being fluidly arranged with other bleed exhaust scrubbers or other sorbent volumes in the evaporative emission control canister system in a series configuration, a parallel configuration, or a combination thereof.

[0020] In another aspect of the disclosure, an evaporative emission control system includes a fuel tank for storing fuel, an engine adapted to receive and consume fuel from the fuel tank, and an evaporative emission control canister system fluidly coupled to the engine, the evaporative emission control canister system including at least one bleed discharge scrubber fluidly coupled to the evaporative emission control canister, the bleed discharge scrubber including an adsorbent volume, the adsorbent volume including at least one hydrocarbon adsorbent structure including a zeolite having a silica to alumina ratio of at least 20, the zeolite having a repeatable TGA butane adsorption of greater than 2 wt.%.

[0021] In some embodiments, the evaporative emission control system further comprises a plurality of bleed discharge scrubbers, each of the plurality of bleed discharge scrubbers being in fluid arrangement with other bleed discharge scrubbers or other sorbent volumes in the evaporative emission control canister system in a series configuration, a parallel configuration, or a combination thereof.

[0022] In another embodiment of the present disclosure, the zeolite comprises micropores that account for at least about 90% of the total pore volume of the zeolite. The micropores have a pore width of less than 20 Å and are capable of transporting hydrogen (H + ) or ammonium (NH4 + ) ion exchanged and having a silica to alumina ratio of the zeolite that is greater than about 100, greater than about 150, or greater than about 200. In some embodiments, the zeolite is in the form of zeolite particles characterized by an average d90 particle size of about 5 micrometers to about 50 micrometers. In some embodiments, the zeolite comprises a zeolite selected from the group consisting of AEI, BEA, BEC, CHA, EMT, FAU, FER, MFI, and combinations thereof. In some embodiments, the zeolite comprises a BEA zeolite. In some embodiments, the zeolite comprises an MFI zeolite.

[0023] In another aspect of the disclosure, a slurry comprises a binder and a zeolite as described herein.

[0024] In another aspect of the disclosure, the adsorbent bed comprises adsorbent particles comprising the zeolites described herein.

[0025] In another aspect of the disclosure, a bleed exhaust scrubber adapted for use with or incorporated into an evaporative emission control canister system comprises an adsorbent volume. In some embodiments, the adsorbent volume comprises at least one hydrocarbon adsorbent structure comprising a zeolite having a silica to alumina ratio of at least 20, the zeolite having a repeatable TGA butane adsorption of greater than 2 wt.%.

[0026] In some embodiments, the bleed exhaust scrubber is adapted for use in or incorporated into an evaporative emission control canister system having a canister volume of 3.5 L or less, 3.0 L or less, 2.5 L or less, or 2.0 L or less.

[0027] In some embodiments, the zeolite comprises micropores having a pore width of less than 20 Å, at least a portion of the micropores exhibiting a pore volume of greater than 0.01 mL / g. In some embodiments, the zeolite has an average pore width of between 2.0 and 6.7 Å.

[0028] In some embodiments, the hydrocarbon adsorbent structure comprises a hydrocarbon adsorbent coating formed on a substrate, hi some embodiments, the substrate is a ceramic monolith.

[0029] As used herein, the terms "adsorbent" and "adsorbent material" refer to a material that can attach to gas molecules, ions, or other species within its structure. Particular materials include, but are not limited to, clays, metal-organic frameworks, activated alumina, silica gel, activated carbon, molecular sieve carbon, zeolites (e.g., molecular sieve zeolites), polymers, resins, and any of these or other components on which a gas adsorbent material is supported (e.g., various embodiments of the adsorbent materials described herein, etc.). Certain adsorbent materials can preferentially or selectively attach to particular species.

[0030] As used herein, the term "adsorption capacity" refers to the working capacity of the amount of a chemical species that an adsorbent material can adsorb under specific operating conditions (e.g., temperature and pressure). Units of adsorption capacity, when given in mg / g, correspond to milligrams of gas adsorbed per gram of adsorbent material.

[0031] Also, as used herein, the term "particle" refers to a collection of discrete portions of material each having a maximum dimension in the range of 0.1 μm to 50 mm. The morphology of the particles may be crystalline, semi-crystalline, or amorphous. The size ranges disclosed herein may be mean / average or median sizes unless otherwise specified. It is also noted that the particles need not be spherical, but may be in the form of cubes, cylinders, disks, or any other suitable shape as would be understood by one of ordinary skill in the art. The types of particles may be "powdered" and "granular".

[0032] Also, as used herein, the term "substrate" refers to a material (e.g., ceramic, metal, semi-metal, semi-metal oxide, metal oxide, polymer, paper-based, pulp / semi-pulp product-based, etc.) on or within which an adsorbent material is formed, deposited, or placed (e.g., in the form of a washcoat).

[0033] Also as used herein, the term "washcoat" refers to a thin, adherent coating of material applied to a substrate. A washcoat may be formed by preparing a slurry containing adsorbent particles at a particular solids content (e.g., 10-50% by weight), which is then coated onto the substrate and allowed to dry. In certain embodiments, the substrate may be porous, and the washcoat may be deposited on the outside and / or inside of the pores.

[0034] Also, as used herein, the term "monolith" refers to a single unitary block of a particular material. The single unitary block may be in the form of, for example, a brick, disk, or rod, and may include channels for increased gas flow / distribution. In certain embodiments, multiple monoliths may be deployed together to form a desired shape. In certain embodiments, the monolith may have a honeycomb structure with multiple parallel channels, each having a square, hexagonal, or other shape. In certain embodiments, multiple monoliths having honeycomb structures may be stacked together. The monolith may be used as a substrate on which the adsorbent material is formed.

[0035] Also, as used herein, the term "dispersant" refers to a compound that helps maintain solid particles in suspension in a fluid medium and inhibits or reduces the aggregation or settling of the particles in the fluid medium.

[0036] Also, as used herein, the term "binder" refers to a material that, when included in a coating, layer, or film, promotes the formation of a continuous or substantially continuous structure from one exterior surface of the coating, layer, or film to the opposing exterior surface, is uniformly or semi-uniformly distributed within the coating, layer, or film, and promotes adhesion to and cohesion between the surface and the coating, layer, or film on which it is formed.

[0037] Also, as used herein, the terms "stream" or "flow" refer broadly to any flowing gas that may contain solids (e.g., particulate matter), liquids (e.g., vapors), and / or gas mixtures.

[0038] As discussed herein, the surface area is determined by the Brunauer-Emmett-Teller (BET) method, referred to as "BET surface area", according to DIN ISO 9277:2003-05, which is a revision of DIN 66131. ​​The specific surface area is determined by multipoint BET measurements in the relative pressure range of 0.05 to 0.3 p / p0.

[0039] Also, as used herein, the term "about" when used in connection with a measurand refers to normal variations in that measurand, as would be expected by one of ordinary skill in the art making the measurement and exercising a reasonable level of care for the purpose of the measurement and the precision of the measuring device. For example, when "about" modifies a value, it may be interpreted to mean that the value may vary by ±1%.

[0040] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. [Brief description of the drawings]

[0041] The present disclosure is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings.

[0042] [Figure 1A] FIG. 2 is a cross-sectional view of a bleed discharge scrubber provided in accordance with a first embodiment. [Figure 1B] FIG. 4 is a cross-sectional view of a bleed discharge scrubber provided in accordance with a second embodiment. [Figure 1C] FIG. 11 is a cross-sectional view of a bleed discharge scrubber provided in accordance with a third embodiment. [Diagram 2] FIG. 1 is a schematic diagram of an evaporative emission control system including an evaporative emission control canister and a bleed exhaust scrubber provided in accordance with one embodiment. [Diagram 3] 1 illustrates a fluidly coupled arrangement of a bleed exhaust scrubber, according to certain embodiments. [Figure 4A] 1 is a plot illustrating pore volume as a function of pore width for different adsorbent materials considered herein. [Figure 4B] 1 is a plot illustrating cumulative pore volume as a function of pore width for different adsorbent materials considered herein. [Diagram 5] 1 is a plot illustrating the amount of butane adsorbed as a function of partial pressure for different adsorbent materials considered herein. [Figure 6]1 is a plot illustrating butane adsorption performance of various zeolites compared to a carbon adsorbent. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0043] FIELD OF THE DISCLOSURE Embodiments described herein relate to hydrocarbon adsorbents and bleed exhaust scrubbers incorporating same that may be utilized in hydrocarbon emission control systems. Certain embodiments relate to the use of zeolite-based hydrocarbon adsorbents.

[0044] It has been found that canisters equipped with hydrocarbon scrubbers with a g-total butane working capacity (BWC) of less than 2 grams may pass the CARB LEV III Bleed Emissions Test Procedure (BETP test) in some circumstances. The g-total BWC of the scrubber is measured at a butane concentration of 50% while the concentration of fuel vapors (e.g. butane) to which the scrubber is exposed during the BETP test is as low as 0.5%. Therefore, a sorbent with a relatively high butane adsorption capacity at 0.5% butane can be used to meet this regulation when compared to standard activated carbon sorbent materials used in evaporative emission control applications. This can be confirmed by measuring the butane isotherm of the sorbent material, which quantifies the butane adsorption capacity of the material as a function of butane partial pressure.

[0045] Certain embodiments of the present disclosure relate to adsorbent materials that improve BETP test performance. Such materials contain mesopores and micropores, but differ from standard materials in that there is a significant amount of micropores of small size (e.g., widths less than 20 Å) that adsorb butane at low concentrations. Thus, such materials will have high butane adsorption capacity at the concentrations to which the scrubber is exposed during the BETP test. The measured butane isotherm of this material will rise sharply to butane partial pressures <0.5%, then plateau, and become completely flat thereafter. Zeolite materials with micropores inherently present in the crystalline structure are one possible example category of such materials. Additionally, the pores of zeolites can be chemically modified (e.g., with silanes or alkyl groups) to increase their hydrophobicity, which will increase their preferential adsorption to aliphatic hydrocarbons found in fuel vapors in the presence of more polar species such as water.

[0046] Bleed discharge scrubber embodiment Certain embodiments of the present disclosure relate to a bleed drain scrubber adapted for use in an evaporative emission control canister system. A bleed drain scrubber (also referred to herein as a "scrubber") according to certain embodiments may comprise a sorbent volume comprising a hydrocarbon sorbent structure, such as a coated substrate as described herein. FIG. 1A illustrates an embodiment of a bleed drain scrubber 1, where the coated substrate 2a is a pleated structured media having a hydrocarbon sorbent coating formed thereon. In some embodiments, the coated substrate 2a is a coated monolith. FIG. 1B illustrates an embodiment where the coated substrate 2b is a foam having a hydrocarbon sorbent coating formed thereon. In one embodiment, the foam has more than about 10 pores per inch. In some embodiments, the foam 2b has more than about 20 pores per inch. In some embodiments, the foam has from about 15 to about 40 pores per inch. In one embodiment, the foam is comprised of polyurethane. In some embodiments, the foam comprises reticulated polyurethane. In some embodiments, the polyurethane is a polyether or polyester polyurethane. In some embodiments, the coated substrate may comprise a substrate having multiple stacked coatings formed thereon. For example, in some embodiments, the coatings may be of the same type of adsorbent material, different adsorbent materials, or alternating adsorbent materials. In some embodiments, the substrate may be at least partially formed from the same hydrocarbon adsorbent contained in the coating (e.g., a partially zeolite substrate or a complete zeolite substrate with one or more zeolite coatings formed thereon).

[0047] FIG. 1C illustrates an embodiment in which the coated substrate 2c is an extruded media on which a hydrocarbon adsorbent coating is formed. In some embodiments, the extruded media is a honeycomb (e.g., a monolithic honeycomb structure). The overall shape of the honeycomb can be any suitable geometric shape, including but not limited to circular, cylindrical, or square. Furthermore, the cells of the honeycomb adsorbent can be any geometric shape. A honeycomb with a uniform cross-sectional area for the flow-through passages, such as a square honeycomb with square cross-sectional cells, or a corrugated spirally wound honeycomb, may perform better than a circular honeycomb with square cross-sectional cells in an orthogonal matrix that provides adjacent passages with a range of cross-sectional areas, and thus equally unpurged passages. Without being bound by any theory, it is believed that the more uniform the cell cross-sectional area across the honeycomb face, the lower the diurnal breathing loss (DBL) emissions from the scrubber, due to a more uniform distribution of flow within the scrubber during both the adsorption cycle and the purge cycle.

[0048] Surprisingly, it has been found that bleed exhaust scrubbers incorporating the coated monoliths disclosed herein, in some embodiments, may have a lower butane working capacity (BWC) than competitive monoliths, yet still effectively control hydrocarbon emissions from evaporative emission control canisters under low purge conditions.

[0049] In some embodiments, the bleed discharge scrubber has a g-total butane working capacity (BWC) of less than 2 grams. In some embodiments, the bleed discharge scrubber has a g-total BWC of about 0.1 grams to 1.999 grams. In some embodiments, the bleed discharge scrubber has a g-total BWC of about 0.3 grams to 1.999 grams. In some embodiments, the bleed discharge scrubber has a g-total BWC of about 0.2 grams to 1.999 grams. In some embodiments, the bleed discharge scrubber has a g-total BWC of about 0.4 grams to 1.999 grams. In some embodiments, the bleed discharge scrubber has a g-total BWC of about 0.5 grams to 1.999 grams. In some embodiments, the bleed discharge scrubber has a g-total BWC of about 0.75 grams to 1.999 grams. In some embodiments, the bleed discharge scrubber has a g-total BWC of about 1.0 grams to 1.999 grams. In some embodiments, the bleed discharge scrubber has a g-total BWC of about 1.25 grams to 1.999 grams. In some embodiments, the bleed discharge scrubber has a g-total BWC of about 1.5 grams to 1.999 grams. In some embodiments, the bleed discharge scrubber has a g-total BWC of about 1.75 grams to 1.999 grams. In some embodiments, the bleed discharge scrubber has a g-total BWC of about 1.9 grams to 1.999 grams. In some embodiments, the bleed discharge scrubber has a g-total BWC of about 1.95 grams to 1.999 grams. In some embodiments, the bleed discharge scrubber has a g-total BWC of about 0.1 grams to about 1.9 grams. In some embodiments, the bleed discharge scrubber has a g-total BWC of about 0.1 grams to about 1.75 grams. In some embodiments, the bleed discharge scrubber has a g-total BWC of about 0.1 grams to about 1.5 grams. In some embodiments, the bleed discharge scrubber has a g-total BWC of about 0.1 grams to about 1.25 grams. In some embodiments, the bleed discharge scrubber has a g-total BWC of about 0.1 grams to about 1.0 grams. In some embodiments, the bleed discharge scrubber has a g-total BWC of about 0.1 grams to about 0.75 grams.In some embodiments, the bleed discharge scrubber has a g-total BWC of about 0.1 grams to about 0.5 grams. In some embodiments, the bleed discharge scrubber has a g-total BWC of about 0.1 grams to about 0.3 grams. In some embodiments, the bleed discharge scrubber has a g-total BWC of about 0.75 grams to about 1.5 grams. In some embodiments, the bleed discharge scrubber has a g-total BWC of about 0.75 grams to about 1.25 grams. In some embodiments, the bleed discharge scrubber has a g-total BWC of about 0.75 grams to about 1.0 grams. As used herein, "g-total BWC" refers to the total mass of butane adsorbed under standard test conditions (e.g., ASTM D5228).

[0050] In some embodiments, the bleed discharge scrubber has an effective butane working capacity (BWC) of less than 3 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 0.1 g / dL to less than 3 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 0.25 g / dL to less than 3 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 0.5 g / dL to less than 3 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 0.75 g / dL to less than 3 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 1 g / dL to less than 3 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 1.25 g / dL to less than 3 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 1.5 dL to less than 3 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 1.75 g / dL to less than 3 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 1.5 g / dL to less than 3 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 1.75 g / dL to less than 3 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 2 dL to less than 3 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 2.25 g / dL to less than 3 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 2.5 g / dL to less than 3 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 2.75 g / dL to less than 3 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 1.0 g / dL to about 2.5 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 1.0 g / dL to about 2.25 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 1.5 g / dL to about 2 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 1.5 g / dL to about 1.75 g / dL.In some embodiments, the bleed discharge scrubber has an effective BWC of about 1.25 g / dL to less than 3 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 1.25 g / dL to about 2.5 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 1.25 g / dL to about 2.25 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 1.5 g / dL to about 2.5 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 1.5 g / dL to about 2.25 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 1.75 g / dL to about 2.5 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 1.75 g / dL to about 2.25 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 2 g / dL to about 2.5 g / dL. In some embodiments, the bleed discharge scrubber has an effective BWC of about 2 g / dL to about 2.25 g / dL.

[0051] As used herein, "effective butane working capacity" refers to the g-total BWC divided by the effective adsorbent volume, which corrects for voids, air gaps, and other non-adsorbent volume.

[0052] Canister embodiment In certain embodiments, the coated substrates and / or scrubbers disclosed herein may be used as components of an evaporative emission control canister. In one embodiment, the evaporative emission control canister comprises a sorbent volume, a fuel vapor purge tube for connecting the evaporative emission control canister to an engine, a fuel vapor inlet conduit for venting the fuel tank to the evaporative emission control canister, a vent conduit for venting the evaporative emission control canister to atmosphere and for purging air into the evaporative emission control canister, and a bleed exhaust scrubber as described herein. The bleed exhaust scrubber may be in fluid communication with the evaporative emission control canister. In some embodiments, the evaporative emission control canister may be used as a component of an evaporative emission control system. Accordingly, further non-limiting embodiments of evaporative emission control canisters and scrubbers are described herein with reference to such evaporative emission control systems.

[0053] In certain embodiments, a canister can include multiple sorbent volumes, each of which may contain a different sorbent or device containing a sorbent therein. More than one of the sorbent volumes may be fluidly coupled to one another such that one or more sorbent materials contained therein are fluidly coupled in parallel, in series, or a combination of both.

[0054] Evaporative Emission Control System Embodiments In certain embodiments, the evaporative emission control system includes a fuel tank for storing fuel, an engine (e.g., an internal combustion engine or a hybrid engine) adapted to consume the fuel, an evaporative emission control canister with a sorbent volume, a fuel vapor purge line connecting the evaporative emission control canister to the engine, a fuel vapor inlet conduit for venting the fuel tank to the evaporative emission control canister, a vent conduit for venting the evaporative emission control canister to atmosphere and for allowing purge air into the evaporative emission control canister system, and a bleed exhaust scrubber as described herein. The bleed exhaust scrubber may be in fluid communication with the evaporative emission control canister.

[0055] In some embodiments, the evaporative emission control system may be configured to allow continuous contact of the sorbent volume with the fuel vapor. In some embodiments, the evaporative emission control system may be defined by a fuel vapor flow path from a fuel vapor inlet conduit through an evaporative emission control canister to a bleed exhaust scrubber to a vent conduit, and a reciprocal air flow path from the vent conduit through the bleed exhaust scrubber to the evaporative emission control canister and to a fuel vapor purge tube.

[0056] In some embodiments, evaporative emissions from the fuel tank are adsorbed by the evaporative emission control system during engine shutdown. Fuel vapors that bleed from the fuel tank can be removed by an adsorbent in the canister system, thereby reducing the amount of fuel vapors released into the atmosphere. During engine operation, ambient air is introduced into the canister system and the bleed exhaust scrubber as a purge stream. Hydrocarbons previously adsorbed by the hydrocarbon adsorbent can then be desorbed and recirculated to the engine for combustion via a purge line.

[0057] In some embodiments, the evaporative emission control canister of the evaporative emission control system comprises a three-dimensional hollow interior space or chamber defined at least in part by a shaped planar material, such as a molded thermoplastic olefin. In some embodiments, the bleed discharge scrubber is disposed within the sorbent volume of the evaporative emission control canister. In other embodiments, the bleed discharge scrubber is disposed in a separate canister in fluid communication with the evaporative emission control canister. In some embodiments, an evaporative emission control system according to an embodiment in which the bleed discharge scrubber is disposed in a separate canister is illustrated in FIG. 2.

[0058] FIG. 2 illustrates diagrammatically an evaporative emission control system 30 according to certain embodiments of the present disclosure. The evaporative emission control system 30 comprises a fuel tank 38 for storing fuel (having a fuel inlet 44), an engine 32 (which may be an internal combustion engine or a hybrid engine) adapted to consume fuel and coupled to the fuel tank 38 via a fuel line 40, an evaporative emission control canister 46, and a bleed exhaust scrubber 1. The engine 32 may be, for example, an engine controlled by a controller 34 via a signal lead 36. In some embodiments, the engine 32 burns gasoline, ethanol, and / or other volatile hydrocarbon-based fuels. The controller 34 may be a separate controller or may form part of an engine control module (ECM), a powertrain control module (PCM), or any other vehicle control device.

[0059] In some embodiments, the evaporative emission control canister 46 includes a sorbent volume 48, a fuel vapor purge line 66 connecting the evaporative emission control canister 46 to the engine 32, a fuel vapor inlet conduit 42 for venting the fuel tank 38 to the evaporative emission control canister 46, and vent conduits 56, 59, 60 for venting the evaporative emission control canister 46 to atmosphere and for allowing purge air to enter the evaporative emission control system 30.

[0060] The evaporative emission control system 30 is further defined by a fuel vapor flow path from the fuel vapor inlet conduit 42 through the sorbent volume 48 through a vent conduit 56 to the bleed discharge scrubber 1 to vent conduits 59, 60, and by a reciprocal air flow path from the vent conduits 60, 59 through the bleed discharge scrubber 58 through vent conduit 56 to the sorbent volume 48 and to a fuel vapor purge tube 66. The bleed discharge scrubber 1 comprises one or more sorbent volumes, some or all of which include any of the coated substrates adapted for hydrocarbon adsorption described herein.

[0061] Fuel vapors containing evaporated hydrocarbons from the fuel tank 38 may pass from the fuel tank 38 through the evaporated vapor inlet conduit 42 to a sorbent volume 48 in the canister 46. In some embodiments, there may be sorbent volumes in addition to the sorbent volume 48, which may be connected in series or parallel with the sorbent volume 48. The evaporative emission control canister 46 may be formed from any suitable material, for example, a molded thermoplastic polymer such as nylon is typically used.

[0062] As the temperature of the gasoline in the fuel tank 38 increases, the fuel vapor pressure increases. Without the evaporative emission control system 30, the fuel vapors would be released untreated into the atmosphere. However, in accordance with the present disclosure, the fuel vapors are treated by the evaporative emission control canister 46 and by the bleed exhaust scrubber 1 (or in some embodiments, an additional bleed exhaust scrubber) located downstream of the evaporative emission control canister 46.

[0063] When vent valve 62 is open and purge valve 68 is closed, fuel vapors flow under pressure from fuel tank 38 through evaporative vapor inlet conduit 42, canister vapor inlet 50, and sequentially through sorbent volume 48 contained within evaporative emission control canister 46. Fuel vapors not adsorbed by sorbent volume 48 subsequently exit evaporative emission control canister 46 via vent conduit opening 54 and vent conduit 56. The fuel vapors then enter bleed discharge scrubber 1 for further adsorption. After passing through bleed discharge scrubber 1, any remaining fuel vapors exit bleed discharge scrubber 1 via conduit 59, vent valve 62, and vent conduit 60.

[0064] Gradually, the hydrocarbon sorbent material contained in both the evaporative emission control canister 46 and the sorbent volume of the bleed exhaust scrubber 1 becomes laden with hydrocarbons adsorbed from the fuel vapors. When the hydrocarbon sorbent material becomes saturated with hydrocarbons, the hydrocarbons must be desorbed in order to continue using the hydrocarbon sorbent to control fuel vapors exhausted from the fuel tank 38. During engine operation, the engine controller 34 commands the valves 62 and 68 to open via signal leads 64 and 70, respectively, to create an air flow pathway between the atmosphere and the engine 32. Opening the purge valve 68 allows clean air to be drawn into the bleed exhaust scrubber 1 and subsequently from the atmosphere via vent conduits 60, 59, and 56 into the evaporative emission control canister 46. The clean air, or purge air, flows through the clean air vent conduit 60, through the bleed exhaust scrubber 1, through vent conduit 56, through vent conduit opening 54, and into the evaporative emission control canister 46. The clean air flows past and / or through the bleed exhaust scrubber 1 and the hydrocarbon adsorbents contained within the emission control canister 46 to desorb the hydrocarbons from the saturated hydrocarbon adsorbents within each volume. The purge air and hydrocarbon stream then exits the evaporative emission control canister 46 through the purge opening outlet 52, the purge line 66, and the purge valve 68. The purge air and hydrocarbons flow through a purge line 72 to the engine 32 where the hydrocarbons are subsequently combusted.

[0065] 2 illustrates the bleed discharge scrubber 1 disposed external to the evaporative emission control canister 46. In other embodiments, the bleed discharge scrubber 1 may be disposed within the evaporative emission control canister 46, for example, within the sorbent volume 48. In other embodiments, the evaporative emission control system 30 may include multiple bleed discharge scrubbers that may be included within one or more sorbent volumes of the evaporative emission control canister 46, outside of but in fluid communication with the evaporative emission control canister 46, or a combination of both.

[0066] In some embodiments, the sorbent volume of the bleed discharge scrubber 1 (and any additional sorbent volumes) may include a volumetric diluent. Non-limiting examples of volumetric diluents may include, but are not limited to, spacers, inert gaps, foams, fibers, springs, channels in the monolith, structural non-sorbent material in the monolith, or combinations thereof. Additionally, the evaporative emission control canister 46 may include empty volume anywhere in the system. As used herein, the term "empty volume" refers to a volume that does not contain any sorbent. Such volumes may include any non-sorbent material, including, but not limited to, air gaps, foam spacers, screens, or combinations thereof.

[0067] 3 illustrates a fluid coupling arrangement for bleed discharge scrubbers, according to certain embodiments. Each of the evaporative emission control canisters 302, 312, and 322 includes a plurality of adsorbent volumes 304, 314, and 324, respectively. The bleed discharge scrubbers 304, 314, and 324 are disposed within the adsorbent volumes 304, 314, and 324, respectively. The bleed discharge scrubbers 304 are fluidly coupled in a series arrangement. The bleed discharge scrubbers 314 are fluidly coupled in a parallel arrangement. The bleed discharge scrubbers 324 are fluidly coupled in a series and parallel combination, with the parallel coupling of bleed discharge scrubbers 324A and 324B being in series with bleed discharge scrubber 324C.

[0068] In some embodiments, one or more of the bleed exhaust scrubbers may be located external to their respective evaporative emission control canisters, but may be fluidly coupled to one or more of the bleed exhaust scrubbers disposed therein, or to another device or sorbent volume disposed therein. In some embodiments, one or more bleed exhaust scrubbers may be disposed within a single sorbent volume (e.g., in series with one another).

[0069] Base material In certain embodiments, the hydrocarbon adsorbent is disposed on a substrate. An article including a coated substrate, such as a bleed exhaust scrubber, may be part of an evaporative emission control system in some embodiments. In general, the substrate is three-dimensional, having a length and diameter and volume similar to a cylinder. The shape does not necessarily conform to a cylinder. The length is the axial length defined by the inlet and outlet ends. The diameter is the maximum cross-sectional length, e.g., if the shape does not conform exactly to a cylinder, the maximum cross-section. In one or more embodiments, the substrate is a monolith, as described herein below.

[0070] In some embodiments, the monolith may be of the type having fine parallel gas flow passages extending therethrough from the inlet or outlet faces of the substrate such that the passages are open to fluid flow therethrough. The passages, which may be essentially straight-line paths or may be patterned paths (e.g., zigzag, herringbone, etc.) from their fluid inlets to their fluid outlets, are defined by walls onto which the adsorbent material is coated as a washcoat such that gas flowing through the passages contacts the adsorbent material. The flow passages of the monolith are thin-walled channels, which may be of any suitable cross-sectional shape and size, such as trapezoidal, rectangular, square, triangular, sinusoidal, hexagonal, elliptical, circular, etc. Such structures may include from about 60 to about 900 or more gas inlet openings per square inch of cross section (i.e., cells per square inch). The monolithic substrate may be constructed of, for example, metal, ceramic, plastic, paper, impregnated paper, etc. In some embodiments, the substrate is a ceramic monolith.

[0071] In some embodiments, the substrate is selected from the group consisting of foams, monolithic materials, nonwovens, woven fabrics, sheets, papers, twisted helices, ribbons, extruded structural media, rolled structural media, folded structural media, pleated structural media, corrugated structural media, poured structural media, bonded structural media, and combinations thereof.

[0072] In one embodiment, the substrate is an extrusion media. In some embodiments, the extrusion media is a honeycomb. The honeycomb can be of any geometric shape, including but not limited to circular, cylindrical, or square. Additionally, the cells of the honeycomb substrate can be of any geometric shape.

[0073] In one embodiment, the substrate is a foam. In some embodiments, the foam has more than about 10 pores per inch. In some embodiments, the foam has more than about 20 pores per inch. In some embodiments, the foam has from about 15 to about 40 pores per inch. In some embodiments, the foam is a polyurethane. In some embodiments, the foam is a reticulated polyurethane. In some embodiments, the polyurethane is a polyether or polyester. In some embodiments, the substrate is a nonwoven fabric.

[0074] In some embodiments, the substrate is a plastic. In some embodiments, the substrate is a thermoplastic polyolefin. In some embodiments, the substrate is a thermoplastic polyolefin containing glass or inorganic fillers. In some embodiments, the substrate is a plastic selected from the group consisting of polypropylene, nylon-6, nylon-6,6, aromatic nylon, polysulfone, polyethersulfone, polybutylene terephthalate, polyphthalamide, polyoxymethylene, polycarbonate, polyvinyl chloride, polyester, and polyurethane.

[0075] Hydrocarbon Adsorbent Coating In certain embodiments, the hydrocarbon adsorbent comprises a material capable of reversibly adsorbing hydrocarbons, which may include, for example, activated carbon, zeolites, metal organic frameworks, metal oxides, and combinations thereof.

[0076] In some embodiments, the hydrocarbon adsorbent comprises a zeolite. In some embodiments, the zeolite can be an aluminosilicate material or a silica-aluminophosphate material. The zeolite can be identified by a three-letter code designated by the International Zeolite Association. In some embodiments, the zeolite can include, for example, AEI, AFT, AFX, BEA, BEC, CHA, DDR, EMT, ERI, EUO, FAU, FER, GME, HEU, KFI, LEV, LTA, LTL, MAZ, MEL, MFI, MFS, MOR, MTN, MTT, MTW, MWW, NES, OFF, PAU, RHO, SFW, TON, UFI, or combinations thereof. In some embodiments, the zeolite can include, for example, zeolite X, zeolite Y, ultrastable zeolite Y, ZSM-5 zeolite, offretite, beta zeolite, ferrierite, faujasite, chabazite, mordenite, clinoptilolite, silicalite, or combinations thereof, In some embodiments, the zeolite is a beta zeolite having a high silica to alumina ratio.

[0077] In certain embodiments, the hydrocarbon adsorbent comprises a combination of adsorbent materials, such as, for example, zeolite particles mixed with activated carbon particles. The activated carbon can be synthetic activated carbon or can be based on or derived from wood, peat, coconut shells, lignite, petroleum pitch, petroleum coke, coal tar pitch, fruit pits, nuts, shells, sawdust, wood flour, synthetic polymers, natural polymers, and combinations thereof.

[0078] In certain embodiments, the zeolite comprises micropores and mesopores. Micropores correspond to pores having a width of less than 20 Å. In some embodiments, the pores have a width of 2.0 Å to 6.7 Å, or 4.0 Å to 6.5 Å. In some embodiments, the micropores occupy 70%, 80%, 90% or more of the total pore volume of the zeolite.

[0079] In some embodiments, the zeolite has a silica to alumina ratio of greater than about 100, greater than about 150, greater than about 200, or greater than about 250.

[0080] In some embodiments, the zeolite is in the form of zeolite particles. The zeolite particles may be characterized by an average d90 particle size of about 5 micrometers to about 50 micrometers, about 10 micrometers to about 25 micrometers, or about 15 micrometers to about 20 micrometers.

[0081] In certain embodiments, the BET surface area of ​​the adsorbent is about 20 m 2 / g ~ approx. 5,000m 2 / g, or more. In certain embodiments, the BET surface area of ​​the adsorbent is about 20 m 2 / g ~ approx. 4,000m 2 / g, about 20m 2 / g ~ approx. 3,000m 2 / g, about 20m 2 / g ~ approx. 2,500m 2 / g, about 20m 2 / g ~ approx. 2,000m 2 / g, about 20m 2 / g ~ approx. 1,000m 2 / g, about 20m 2 / g~about 500m 2 / g, about 20m 2 / g~about 300m 2 / g, about 100m 2 / g ~ approx. 5,000m 2 / g, about 100m 2 / g ~ approx. 4,000m 2 / g, about 100m 2 / g ~ approx. 3,000m 2 / g, about 100m 2 / g ~ approx. 2,500m 2 / g, about 100m 2 / g ~ approx. 2,000m 2 / g, about 100m 2 / g ~ approx. 1,000m 2 / g, about 100m 2 / g~about 500m 2 / g, about 100m 2 / g~about 300m2 / g, about 300 m 2 / g to about 5,000 m 2 / g, about 300 m 2 / g to about 4,000 m 2 / g, about 300 m 2 / g to about 3,000 m 2 / g, about 300 m 2 / g to about 2,500 m 2 / g, about 300 m 2 / g to about 2,000 m 2 / g, about 300 m 2 / g to about 1,000 m 2 / g, about 300 m 2 / g to about 500 m 2 / g, about 750 m 2 / g to about 5,000 m 2 / g, about 750 m 2 / g to about 4,000 m 2 / g, about 750 m 2 / g to about 3,000 m 2 / g, about 750 m 2 / g to about 2,500 m 2 / g, about 750 m 2 / g to about 2,000 m 2 / g, about 750 m 2 / g to about 1,000 m 2 / g, about 1,200 m 2 / g to about 5,000 m 2 / g, about 1,200 m 2 / g to about 4,000 m 2 / g, about 1,200 m 2 / g to about 3,000 m 2 / g, about 1,200 m 2 / g to about 2,500 m 2 / g, about 1,500 m 2 / g to about 5,000 m 2 / g, about 1,750 m 2 / g to about 5,000 m 2 / g, about 2,000 m 2 / g to about 5,000 m 2 / g, about 2,500 m 2 / g to about 5,000 m 2 / g, about 3,000 m 2 / g to about 5,000 m 2 / g, approx. 3,500m 2 / g ~ approx. 5,000m 2 / g, or approximately 4,000m 2 / g ~ approx. 5,000m 2 / g.

[0082] In some embodiments, the hydrocarbon adsorbent is prepared as a slurry that is washcoated onto the substrate. In some embodiments, the loading of the hydrocarbon adsorbent on the substrate is greater than 1 g / in 3 In some embodiments, the loading is less than 0.5 g / in 3 ~1g / in 3 , or 0.75 g / in 3 ~1g / in 3である In some embodiments, the loading is 1 g / in 3 In some embodiments, the loading is greater than 1 g / in 3 ~1.25g / in 3 , 1.25g / in 3 ~1.5g / in 3 , 1.5g / in 3 ~1.75g / in 3 , or 1.75 g / in 3 ~2g / in 3 It is.

[0083] In some embodiments, the coating thickness of the hydrocarbon adsorbent is greater than 50 micrometers and less than about 500 micrometers, less than 400 micrometers, less than 300 micrometers, less than 200 micrometers, or less than 100 micrometers.

[0084] In some embodiments, the coated substrate has dimensions that accommodate use in a vapor canister having a volume of 2.0 L or less (e.g., a 1.9 L vapor canister). In some embodiments, the coated substrate has dimensions that accommodate use in a canister having a volume of more than 2.0 L (e.g., a 3.5 L vapor canister). Binder

[0085] In some embodiments, the hydrocarbon adsorbent may further include a binder, which may help promote adhesion of the hydrocarbon adsorbent to a substrate. In some embodiments, the binder may crosslink with itself to provide improved adhesion. The presence of the binder may increase the integrity of the hydrocarbon adsorbent, improve adhesion to the substrate, and provide structural stability under vibration conditions experienced in automotive vehicles.

[0086] The binder may also include additives to improve water resistance and improve adhesion. Typical binders for use in the formulation of the slurry include, but are not limited to, the following organic polymers; sols of alumina, silica, or zirconia; inorganic salts, organic salts, and / or hydrolysis products of aluminum, silica, or zirconium; hydroxides of aluminum, silica, or zirconium; organic silicates hydrolyzable to silica; and mixtures thereof. In some embodiments, the binder includes a zirconium salt (e.g., zirconium acetate). In some embodiments, the binder is an organic polymer. The organic polymer may be a thermosetting or thermoplastic polymer and may be a plastic or an elastomer. The binder may be, for example, an acrylic / styrene copolymer latex, a styrene-butadiene copolymer latex, a polyurethane, or any mixture thereof. The polymer binder may contain suitable stabilizers and anti-aging agents known in the art. In some embodiments, the binder is a thermosetting elastomeric polymer that is introduced into the slurry (e.g., the aqueous slurry) as a latex.

[0087] Examples of suitable binders include, but are not limited to, polyethylene, polypropylene, polyolefin copolymers, polyisoprene, polybutadiene, polybutadiene copolymers, chlorinated rubber, nitrile rubber, polychloroprene, ethylene-propylene-diene elastomers, polystyrene, polyacrylates, polymethacrylates, polyacrylonitrile, poly(vinyl esters), poly(vinyl halides), polyamides, cellulosic polymers, polyimides, acrylics, vinyl acrylics, styrene acrylics, polyvinyl alcohols, thermoplastic polyesters, thermoset polyesters, poly(phenylene oxides), poly(phenylene sulfides), fluorinated polymers such as poly(tetrafluoroethylene), polyvinylidene fluoride, poly(vinyl fluoride), chloro / fluoro copolymers such as ethylene chlorotrifluoro-ethylene copolymers, polyamides, phenolic resins, epoxy resins, polyurethanes, acrylic / styrene acrylic copolymer latexes, and silicone polymers.

[0088] In some embodiments, the polymeric binder comprises an acrylic / styrene acrylic copolymer latex, such as a hydrophobic styrene-acrylic emulsion. In some embodiments, the binder is selected from an acrylic / styrene copolymer latex, a styrene-butadiene copolymer latex, a polyurethane, and mixtures thereof. In some embodiments, the binder comprises an acrylic / styrene copolymer latex and a polyurethane dispersion.

[0089] In certain embodiments, the binder, or mixture of binders, is present at about 5% to about 50% by weight based on the total weight of the hydrocarbon adsorbent when dried and deposited on the substrate. In certain embodiments, the polymer binder is present at about 5% to about 30% by weight, about 10% to about 30% by weight, about 15% to about 30% by weight, about 5% to about 25% by weight, about 5% to about 20% by weight, about 5% to about 15% by weight, about 10% to about 20% by weight, or about 15% to about 20% by weight.

[0090] In some embodiments, the organic binder may have a low glass transition temperature. The transition temperature is conventionally measured by differential scanning calorimetry (DSC) by methods known in the art. An exemplary hydrophobic styrene-acrylic emulsion binder with a low transition temperature is RHOPLEX™ P-376. In some embodiments, the binder has a transition temperature below about 0° C. An exemplary binder with a transition temperature below about 0° C. is RHOPLEX™ NW-1715K (RHOPLEX™ brand products are available from Dow). In some embodiments, the binder is an alkylphenol ethoxylate (APEO)-free, ultra-low formaldehyde styrenated acrylic emulsion. One such exemplary binder is Joncryl® 2570. In some embodiments, the binder is an aliphatic polyurethane dispersion. One such exemplary binder is Joncryl® FLX 5200 (Joncryl® brand products are available from BASF).

[0091] Further Exemplary Additives In some embodiments, the hydrocarbon sorbent may contain additional additives, such as thickeners, dispersants, surfactants, biocides, antioxidants, etc., which may be added to the slurry prior to forming the hydrocarbon sorbent on the substrate. The thickener, for example, allows for a sufficient amount of coating to be achieved on a substrate with a relatively low surface area. The thickener may also play a secondary role by increasing the stability of the slurry through steric hindrance of the dispersed particles. It may also promote coating surface bonding. Exemplary thickeners include xanthan gum thickeners or carboxymethyl cellulose thickeners. Kelzan® CC (available from CP Kelco) is one such exemplary xanthan thickener.

[0092] In some embodiments, a dispersant is used in combination with the binder. The dispersant may be anionic, cationic, or nonionic and may be utilized in an amount of about 0.1% to about 10% by weight based on the weight of the hydrocarbon adsorbent. Suitable dispersants may include, but are not limited to, polyacrylates, alkoxylates, carboxylates, phosphate esters, sulfonates, taurates, sulfosuccinates, stearates, laurates, amines, amides, imidazolines, sodium dodecylbenzenesulfonate, sodium dioctyl sulfosuccinate, and mixtures thereof. In some embodiments, the dispersant is a low molecular weight polyacrylic acid in which many of the protons on the acid are replaced with sodium. In some embodiments, the dispersant is an ammonium polycarboxylate salt. In some embodiments, the dispersant is a hydrophobic copolymer pigment dispersant. An exemplary dispersant is Tamol™ 165A (a trademark of Dow Chemical). Increasing the pH of the slurry or adding an anionic dispersant alone can provide sufficient stability to the slurry mixture, but improved results can be obtained by using both an increased pH and an anionic dispersant. In some embodiments, the dispersant is a non-ionic surfactant such as Surfynol® 420 (Air Products and Chemicals, Inc.). In some embodiments, the dispersant is an acrylic block copolymer such as Dispex® Ultra PX 4575 (BASF).

[0093] In some embodiments, it is preferred to use a surfactant that can act as an antifoaming agent. In some embodiments, the surfactant is a low molecular weight non-anionic dispersant. An exemplary oil- and silicone-free antifoaming surfactant is Rhodoline® 999 (Solvay). Another exemplary surfactant is a blend of hydrocarbons and non-ionic surfactants such as Foammaster® NXZ (BASF).

[0094] Illustrative Examples The following examples are provided to aid in the understanding of the present disclosure and should not be construed as specifically limiting the embodiments described and claimed herein. Such variations of the embodiments, including the substitution of all currently known or later developed equivalents that would be within the understanding of a person skilled in the art, and slight changes in formulation or experimental design should be considered within the scope of the embodiments incorporated herein.

[0095] Example 1: Preparation of zeolite-coated monoliths 298.8 g of water was mixed with Zeolite 3 from Example 5 (below) and the combination was thoroughly mixed in a Ross high shear mixer. The resulting suspension was then milled in an Eiger continuous mill until the d90 particle size was 17.8 microns. 50.59 g of a 30% zirconium acetate solution and 2 drops of octanol were then mixed to form the final slurry.

[0096] A cylindrical ceramic monolith substrate (230 cells per square inch) measuring 29 x 100 mm (cylinder width x length) was immersed in the slurry. Excess slurry was removed by clearing the channels using an air knife operating at a pressure of 55 psig. The substrate was dried at 110 °C for 1 hour and then calcined in air at 300 °C for 3 hours. The final loading of the coating on the substrate was 1.76 g / in 3 It was.

[0097] Comparative Example 1 A commercially available extruded carbon-based bleed exhaust trap of 29x100mm (cylinder diameter x length) and 200 cells per square inch was tested as described below. The carbon content was determined to be 31.8 wt% by loss on ignition (LOI). The total weight of the monolith was approximately 28g. This carbon content was used to plot the measured pore volume in Example 2 below.

[0098] Example 2: Measurement of pore size distribution Nitrogen pore size distribution and surface area analysis was performed on a Micromeritics TriStar 3000 series instrument. The material to be tested was degassed in a Micromeritics SmartPrep degasser for a total of 6 hours (2 hour ramp to 300°C under a flow of dry nitrogen, then held at 300°C for 4 hours). Nitrogen BET surface area was determined using 5 partial pressure points from .08 to 0.20. Nitrogen pore size was determined using BJH calculations and 33 desorption points.

[0099] Figure 4A shows the pore size distribution of beta zeolite (Zeolite 3 from Example 5) versus a commercial monolithic carbon, and Figure 4B shows the corresponding cumulative pore size distribution. In this graph, one can see the relatively small amount of mesopores present in Zeolite 3, but still has a significant amount of micropores.

[0100] Example 3: Measurement of butane isotherm Butane isotherm measurements measure the amount of butane adsorbed in a sample material as a function of butane partial pressure. Butane is slowly introduced into the evacuated sample, allowed to reach equilibrium, and the mass adsorbed is measured. The procedure used for this example is as follows: Approximately 0.1 g of material sample is degassed under vacuum at 120° C. for 960 minutes and the butane isotherm measured using the 3Flex high resolution high throughput surface characterization instrument. The adsorptive test gas used is butane and the backfill gas used is nitrogen. A temperature of 298 K was maintained during the analysis with a circulating bath of water and antifreeze mixture. The low pressure dose is 0.5 cc / g up to 0.000000100 p / p0 and 3.0 cc / g up to 0.001 p / p0. An equilibration interval of 30 seconds is used up to 0.001 p / p0 and 10 seconds for the remaining isotherms.

[0101] FIG. 5 shows the butane isotherms for Zeolite 3 versus commercial monolithic carbon. In this plot, both materials are sized to show the total amount of butane adsorbed in both scrubbers of size 29x100mm and 35x150mm (diameter x length of cylinder) (Curve 510: Commercial 29x100mm scrubber, Curve 520: Zeolite 3 29x100mm scrubber, Curve 530: Commercial 35x150mm scrubber, Curve 540: Zeolite 3 29x100mm scrubber). This plot shows that even the 35x150mm scrubber coated with Zeolite 3 has a much lower butane adsorption capacity at high butane concentrations than the commercial monolithic carbon, yet still has a relatively high butane adsorption capacity at low concentrations typically experienced during BETP testing compared to the comparative examples.

[0102] At low butane concentrations, butane only adsorbs into the very small micropores of the adsorbent material. At higher butane concentrations, butane also adsorbs into the larger mesopores. Without wishing to be bound by theory, it is believed that adsorption into the larger mesopores explains why the butane isotherm rises continuously from low to high concentrations of butane in the material, since these materials contain a significant amount of both micropores and mesopores.

[0103] Example 4: Measurement of butane adsorption capacity A cylindrical sample of 29 x 100 mm (cylinder diameter x length) was placed in a vertically oriented cylindrical sample cell. The sample cell was then loaded with a 1:1 butane / N2 test gas flow rate of 134 mL / min (10 g / hr butane flow) for 45 min. The flow direction was upward from the bottom to the top of the sample cell. The gas composition of the exit flow from the sample cell was monitored by an FID (Flame Ionization Detector).

[0104] After the 45 min butane adsorption step, the sample cell was purged with N2 at 100 mL / min for 10 min in the same flow direction. The sample was then desorbed with 10 L / min air flow in the opposite direction (top to bottom) for 15 min. In the next step, the gas composition was switched to a mixture of 0.5% butane / N2 (0.1 g butane per hour) at 134 mL / min and the loading step was repeated. The breakthrough curve was recorded using the FID described above, and the signal was plotted against the cumulative mass of butane flowing.

[0105] The relative effective butane adsorption capacity can be correlated to the time at which butane breakthrough occurs through the sample. The butane breakthrough point was arbitrarily defined as the point at which the butane outlet concentration from the sample cell reached 25% of the saturation concentration. Table 1 compares the amount of butane adsorbed at the butane breakthrough point for Example 1 versus Comparative Example 1 at both 50% butane and 0.5% butane. The amount of butane adsorbed is calculated based on the butane flow rate. This test shows that Example 1 has only 19.3% of the relative butane adsorption capacity at 50% butane compared to Comparative Example 1, but 70.5% of the relative butane adsorption capacity at 0.5% butane, demonstrating its relatively high adsorption capacity at low concentrations. [Table 1]

[0106] Example 5: Measurement of butane adsorption in the presence of moisture This test protocol measures the amount of butane that a sample material will repeatedly adsorb and desorb in the presence of moisture. The results of this test can be used to predict the relative performance of sorbent materials used in canister scrubbers for evaporative emission control applications, as these materials must repeatedly adsorb and desorb primarily low concentrations of light hydrocarbon vapors and are exposed to ambient conditions in the presence of moisture. Without wishing to be bound by any particular theory, it is believed that the water molecules present will compete with butane for the adsorption sites of the zeolite, thus reducing the adsorption capacity of the material compared to its performance under dry conditions.

[0107] The procedure used in this example is as follows: A sample of approximately 15 mg of test material is loaded into a TA Instruments Q50 Thermogravimetric Analysis (TGA) unit and purged with wet nitrogen for 2 hours at 42° C. A gas flow of 50 mL / min is provided by a gas mixer that combines two separate gas flows into a single controlled stream, then limited to 50 mL / min by the instrument. The first nitrogen flow stream flows at 43 mL / min through a water bubbler held at 20° C., finally delivering a constant humidity level of 27% at 42° C. to the sample at a flow rate of 50 mL / min. The second flow stream delivers dry nitrogen at 7 mL / min. After 2 hours of purging, a valve is switched so that the second flow at 7 mL / min delivers a stream of 3.5% butane in dry nitrogen that is mixed with the wet nitrogen flow of 43 mL / min before reaching the sample and then diluted to 0.5% butane at 50 mL / min. The sample is loaded with 0.5% butane flow for 3 hours, then the butane-free wet nitrogen flow is restored to allow the sample to desorb for 25 minutes. In this way, the sample is loaded with butane and purged for a total of 3 cycles. The sample temperature is kept constant at 42°C, and the mass of the sample is measured throughout the test.

[0108] In a typical test of a zeolite adsorbent material, the amount of butane adsorbed, given as the weight percent increase (wt%) in the mass of the sample due to butane adsorption, is higher during the first adsorption cycle than during the second and third adsorption cycles. The mass increase during the second and third adsorption cycles is typically similar. This is because the 25 minute desorption step desorbs a relatively constant amount of butane and is not long enough to completely desorb the butane material. In some cases, the sample is not fully saturated with butane after the first adsorption cycle due to slow adsorption rates.

[0109] Using this procedure, 15 samples of zeolites were tested. Two comparative carbon samples were also tested and included for reference. Both comparative carbons are activated carbon materials used in hydrocarbon sorbent coatings. The bar graph in FIG. 6 and Table 2 below show the results, as well as some important physical properties of the tested zeolites, which can be correlated to butane adsorption performance. The bar graph shows (a) the relative amount of butane adsorbed during the first adsorption cycle, and (b) the average of the second and third adsorption cycles, which were within a few percentage points of each other in all cases. This value is referred to herein as "repeatable TGA butane adsorption." The most important indicator of good performance of materials tested by this method in canister scrubber applications is a high value of repeatable TGA butane adsorption. This value takes into account both high adsorption capacity, as well as efficient loading and purging rates. From the physical material properties of these materials listed, it can be seen that several physical properties can be correlated to high performance by this metric, including a high silica-to-alumina ratio (SAR). Without wishing to be bound by any particular theory, this is because butane prefers to adsorb on silicone adsorption sites in the crystalline matrix of the zeolite structure. The zeolite must also have a three-dimensional pore network with a pore size large enough to adsorb butane. For reference, the kinetic diameter of butane is 4.5 Å. Small pore size does not make it easy for butane to enter and desorb.

[0110] Without wishing to be bound by any particular theory, the uniform pore size of zeolites may also represent an advantage in canister scrubber applications in terms of heel build, as they do not allow for the adsorption of the more volatile components of fuel vapors (e.g., isooctane, xylene), which are believed to be the primary cause of heel build-up as a result of fuel vapor aging due to this same size exclusion principle. Also, the ionic form of the zeolite is preferably the proton (H+) form rather than the ammonium (NH+) form. Without wishing to be bound by any particular theory, this is because protons take up less space in the zeolite pores than ammonium ions. The ammonium form of zeolite can be converted to the proton form by calcining the material in air at 550° C. for 6 hours.

[0111] Based on these results, it can be seen that Zeolite 3 is predicted to be an exemplary performance material in canister scrubber applications, which is also the zeolite material used in the previous example above. [Table 2] [Table 3]

[0112] In the preceding description, numerous specific details are set forth, such as specific materials, dimensions, process parameters, etc., to provide a thorough understanding of the embodiments of the present disclosure. Particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments. As used herein, the word "example" or "exemplary" means to serve as an example, illustration, or illustration. Any aspect or design described herein as "example" or "exemplary" should not necessarily be construed as preferred or advantageous over other aspects or designs. Rather, use of the word "example" or "exemplary" is intended to present a concept in a concrete manner. As used in this application, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or." That is, unless otherwise specified or clear from the context, "X includes A or B" is intended to mean any of the natural inclusive combinations. That is, if X includes A, X includes B, or X includes both A and B, then "X includes A or B" is satisfied in any of the above examples. Moreover, in the context of describing the materials and methods discussed herein (particularly in the context of the claims which follow), use of the terms "a," "an," "the," and similar directives should be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context.

[0113] Recitation of ranges of values ​​herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated herein as if it were individually set forth herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context.

[0114] References throughout this specification to "one embodiment," "a particular embodiment," "one or more embodiments," "embodiments," or "some embodiments" mean that a particular feature, structure, material, or characteristic described in connection with an embodiment is included in at least one embodiment of the disclosure. Thus, the appearances of phrases such as "in one or more embodiments," "in a particular embodiment," "in one embodiment," or "in an embodiment" in various places throughout this specification do not necessarily refer to the same embodiment of the disclosure. Furthermore, particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

[0115] It should be understood that the above description is intended to be illustrative, not limiting. Many other embodiments will become apparent to those skilled in the art upon reading and understanding the above description. Therefore, the scope of the present disclosure should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The use of any and all examples or exemplary language (e.g., "etc.") provided herein is intended only to better describe the materials and methods, and does not limit the scope unless otherwise claimed. No language in this specification should be construed as indicating any unclaimed element as essential to the practice of the disclosed materials and methods.

[0116] Although the embodiments disclosed herein are described with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the present disclosure. It will be apparent to those skilled in the art that various modifications and changes can be made to the disclosed method and apparatus without departing from the spirit and scope of the present disclosure. Therefore, the present disclosure is intended to include modifications and changes that fall within the scope of the appended claims and their equivalents, and the above embodiments are presented for the purpose of illustration and not limitation.

Claims

1. 1. A hydrocarbon adsorbent structure comprising: comprising a zeolite having a silica to alumina ratio in the range of 20 to 600; The zeolite has a three-dimensional pore network, The average pore width of the micropores of the zeolite is 4.5 to 6.7 Å; Hydrocarbon adsorbent structures.

2. 2. The hydrocarbon adsorbent structure of claim 1, wherein the silica to alumina ratio is at least 30, at least 50, at least 100, at least 150, at least 200, at least 250, at least 300, at least 350, at least 400, at least 450, or at least 500.

3. 10. The hydrocarbon adsorbent structure of claim 1, wherein the zeolite is in a morphology characterized by an average d90 particle size of from 5 micrometers to 50 micrometers, from 10 micrometers to 25 micrometers, or from 15 micrometers to 20 micrometers.

4. 2. The hydrocarbon adsorbent structure of claim 1, wherein the zeolite comprises a zeolite selected from the group consisting of AEI, BEA, BEC, CHA, EMT, FAU, FER, MFI, and combinations thereof.

5. 10. The hydrocarbon adsorbent structure of claim 1, wherein said zeolite comprises a BEA zeolite.

6. 10. The hydrocarbon adsorbent structure of claim 1, wherein said zeolite comprises an MFI zeolite.

7. 10. The hydrocarbon adsorbent structure of claim 1, wherein the hydrocarbon adsorbent structure comprises a substrate and a hydrocarbon adsorbent coating formed thereon, the hydrocarbon adsorbent coating comprising the zeolite.

8. The hydrocarbon adsorbent structure of claim 7 , wherein the substrate comprises a ceramic monolith.

9. The loading of the hydrocarbon adsorbent coating on the substrate is 0.5 g / in ３ ~2.0g / in ３ , 0.5 g / in ３ ~1g / in ３ , or 1 g / in ３ ~2g / in ３ 8. The hydrocarbon adsorbent structure of claim 7, wherein the molecular weight of the hydrocarbon adsorbent structure is in the range of

10. 8. The hydrocarbon adsorbent structure of claim 7, wherein the hydrocarbon adsorbent coating has a thickness of less than 500 micrometers.

11. The hydrocarbon adsorbent structure of claim 7 , wherein the hydrocarbon adsorbent coating comprises a binder.

12. 12. The hydrocarbon adsorbent structure of claim 11, wherein said binder comprises a styrene / acrylic copolymer.

13. 13. The hydrocarbon adsorbent structure of claim 12, wherein the binder is present in an amount of 5% to 50%, 5% to 30%, or 5% to 15% by weight based on the total weight of the hydrocarbon adsorbent coating.

14. The hydrocarbon adsorbent structure of claim 7 , wherein the hydrocarbon adsorbent coating further comprises activated carbon.

15. 10. The hydrocarbon adsorbent structure of claim 1, wherein the hydrocarbon adsorbent structure is in the form of a monolithic body, and at least 50%, at least 60%, at least 70%, at least 80%, or at least 90% of the zeolite forms the monolithic body.

16. A bleed discharge scrubber comprising adsorbent volumes, at least one adsorbent volume comprising at least one hydrocarbon adsorbent structure according to any one of claims 1 to 15.

17. An air intake system comprising at least one hydrocarbon adsorbent structure according to any one of the preceding claims.

18. A cabin air purification system comprising at least one hydrocarbon adsorbent structure according to any one of claims 1 to 15.

19. 1. An evaporative emission control canister comprising: one or more sorbent volumes disposed within or external to the evaporative emission control canister; and at least one bleed exhaust scrubber contained within and fluidly coupled to the adsorbent volume of the evaporative emission control canister, each bleed exhaust scrubber comprising at least one hydrocarbon adsorbent structure according to any one of claims 1 to 15.

20. 20. The evaporative emission control canister of claim 19, comprising a plurality of bleed discharge scrubbers each comprising at least one hydrocarbon adsorbent structure according to any one of claims 1 to 15, one or more of said bleed discharge scrubbers being contained within a respective adsorbent volume of said evaporative emission control canister.

21. 21. The evaporative emission control canister of claim 20, wherein each of the plurality of bleed discharge scrubbers is in fluid arrangement with other bleed discharge scrubbers or other sorbent volumes within the evaporative emission control canister in a series configuration, a parallel configuration, or a combination thereof.

22. 20. The evaporative emission control canister of claim 19, wherein the bleed drain scrubber is incorporated into an evaporative emission control canister system having a canister volume of 3.5 L or less, 3.0 L or less, 2.5 L or less, or 2.0 L or less.

23. 23. The evaporative emission control canister of claim 22, wherein the volume of the bleed exhaust scrubber or the hydrocarbon adsorber structure is less than 4 dL.

24. 23. The evaporative emission control canister of claim 22, wherein at least a portion of the micropores of the zeolite exhibit a pore volume greater than 0.01 mL / g.

25. 1. An evaporative emissions control system comprising: A fuel tank for storing fuel; an engine adapted to receive and consume fuel from the fuel tank; an evaporative emission control canister system fluidly coupled to the engine, an evaporative emission control canister system comprising at least one bleed discharge scrubber fluidly coupled to an evaporative emission control canister, said at least one bleed discharge scrubber comprising an adsorbent volume, said adsorbent volume comprising at least one hydrocarbon adsorbent structure according to any one of claims 1 to 15.

26. 26. The evaporative emission control system of claim 25, further comprising a plurality of bleed discharge scrubbers, each of the plurality of bleed discharge scrubbers being in fluid arrangement with other bleed discharge scrubbers or other sorbent volumes in the evaporative emission control canister system in a series configuration, a parallel configuration, or a combination thereof.

27. 1. An evaporative emissions control system comprising: A fuel tank for storing fuel; an engine adapted to receive and consume fuel from the fuel tank; an evaporative emission control canister system fluidly coupled to the engine, an evaporative emission control canister system comprising at least one bleed discharge scrubber fluidly coupled to an evaporative emission control canister, said bleed discharge scrubber comprising an adsorbent volume, said adsorbent volume comprising at least one hydrocarbon adsorbent structure comprising a zeolite having a silica to alumina ratio in the range of 20 to 600; The zeolite has a three-dimensional pore network, The evaporative emission control system wherein the average pore width of the zeolite micropores is between 4.5 and 6.7 Å.

28. 28. The evaporative emission control system of claim 27, further comprising a plurality of bleed discharge scrubbers, each of the plurality of bleed discharge scrubbers being in fluid arrangement with other bleed discharge scrubbers or other sorbent volumes in the evaporative emission control canister system in a series configuration, a parallel configuration, or a combination thereof.

29. A zeolite comprising micropores that account for at least 90% of the total pore volume of the zeolite; The zeolite has a three-dimensional pore network, the micropores are 4.5 to 6.7 Å; The zeolite is a hydrogen (H ＋ ) or ammonium (NH ４ ＋ ) is ion-exchanged, The zeolite has a silica to alumina ratio of the zeolite that is greater than 100, greater than 150, or greater than 200.

30. 30. The zeolite of claim 29, wherein the zeolite is in the form of zeolite particles characterized by an average d90 particle size of from 5 micrometers to 50 micrometers.

31. 30. The zeolite of claim 29, wherein the zeolite comprises a zeolite selected from the group consisting of AEI, BEA, BEC, CHA, EMT, FAU, FER, MFI, and combinations thereof.

32. 30. The zeolite of claim 29, wherein the zeolite comprises a BEA zeolite.

33. 30. The zeolite of claim 29, wherein the zeolite comprises an MFI zeolite.

34. A slurry comprising: A binder; A slurry comprising the zeolite according to any one of claims 29 to 33.

35. An adsorbent bed comprising adsorbent particles comprising the zeolite of any one of claims 29 to 33.

Images