Exhaust gas treatment system for dual fuel engines

Abstract

Disclosed herein are emission treatment systems comprising an oxidation catalyst composition in fluid communication with an exhaust gas stream emitted from an engine burning both a hydrocarbon fuel and hydrogen, and optionally at least one selective catalytic reduction (SCR) composition and / or at least one three-way conversion (TWC) catalyst composition, combustion systems comprising all three of the above, and methods of using all three to treat an exhaust gas stream, e.g., produced by burning a hydrogen fuel during a cold start period, etc.

Description

Technical Field

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 039,633, filed June 16, 2020, the contents of which are incorporated herein by reference in their entirety.

[0002] This disclosure generally relates to the field of enhancing the cold start performance of emission treatment systems employing selective catalytic reduction catalysts and oxidation catalysts. Background Technology

[0003] Environmental regulations governing emissions from internal combustion engines are becoming increasingly stringent worldwide. For example, lean-burn engines like diesel engines offer excellent fuel economy due to their high air / fuel ratio operation under low-fuel conditions. However, diesel engines also emit particulate matter (PM), unburned hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx). x The exhaust emissions of NO x This describes various chemical substances containing nitrogen oxides, including nitric oxide and nitrogen dioxide, etc. The two main components of particulate matter in exhaust gases are the soluble organic fraction (SOF) and the soot fraction. SOF condenses on the soot in the form of a layer and typically originates from unburned diesel fuel and lubricating oil. Depending on the exhaust gas temperature, SOF can exist in diesel exhaust gases as vapor or aerosol (i.e., fine droplets of liquid condensate). Soot is primarily composed of carbon particles.

[0004] Platinum group metal (PGM) oxidation catalysts, comprising platinum group metals (PGMs) dispersed on a refractory metal oxide support such as alumina, are known to be used to treat diesel engine exhaust gases in order to convert these pollutants into carbon dioxide and water by catalytic oxidation of both gaseous hydrocarbons and carbon monoxide. Such catalysts are typically contained in a unit called a diesel oxidation catalyst (DOC), which is placed in the exhaust gas flow path from the diesel engine power system to treat the exhaust gases before they are released into the atmosphere. Typically, diesel oxidation catalysts are formed on a ceramic or metal substrate on which one or more catalyst coating compositions are deposited. In addition to converting gaseous HC and CO emissions and particulate matter (SOF portion), PGM-containing oxidation catalysts also promote the oxidation of NO to NO2. Catalysts are typically categorized by their ignition temperature or the temperature at which 50% conversion is achieved (also known as T). 50 Defined by ).

[0005] A method for reducing NO from the exhaust gas of lean-burn engines x An effective method requires reducing NO under lean-burn engine operating conditions. xIt reacts with suitable reducing agents such as ammonia or hydrocarbons in the presence of a selective catalytic reduction (SCR) catalyst. Suitable SCR catalysts contain, for example, metal-containing molecular sieves, such as metal-containing zeolites. Useful SCR catalyst compositions can efficiently catalyze NO at temperatures below 600°C. x The reduction of exhaust gas components to enable the reduction of NO even under low load conditions typically associated with lower exhaust gas temperatures. x content.

[0006] Catalysts used to treat internal combustion engine exhaust gases are less efficient during relatively low-temperature operating cycles, such as the initial cold start cycle of engine operation, because the engine exhaust gases are not at a sufficiently high temperature to effectively catalyze the conversion of harmful components in the exhaust gases. To address this, adsorbent materials, such as zeolites, are known in the art as part of a catalytic treatment system to adsorb and / or absorb gaseous pollutants, such as hydrocarbons, and retain these pollutants during the initial cold start cycle. As the exhaust gas temperature increases, the stored hydrocarbons are expelled from the adsorbent and undergo catalytic treatment at a higher temperature.

[0007] Increasingly stringent emission regulations have driven the need to develop exhaust gas treatment systems with improved CO, HC, and NO oxidation capabilities to manage CO, HC, and NO emissions at low engine exhaust temperatures. For example, PCT International Publication No. WO2018 / 185665 discloses an exhaust gas treatment system that injects hydrogen upstream of the catalyst product to improve low-temperature performance during cold start cycles. Further technological exploration is needed in this field to improve emission treatment systems at low engine exhaust temperatures. Summary of the Invention

[0008] This disclosure provides an emission treatment system comprising: an oxidation catalyst composition disposed on a substrate in fluid communication with an exhaust gas stream from an engine burning both hydrocarbon fuel and hydrogen; and optionally, at least one selective catalytic reduction (SCR) composition disposed downstream of the oxidation catalyst composition on the substrate. In some alternative embodiments, this disclosure provides an emission treatment system comprising: a TWC catalyst composition disposed on a substrate in fluid communication with an exhaust gas stream from an engine burning both hydrocarbon fuel and hydrogen; and optionally, at least one selective catalytic reduction (SCR) composition disposed downstream of the oxidation catalyst composition on the substrate. In addition to the disclosed emission treatment system, this disclosure also provides a combustion system comprising an engine suitable for burning both hydrocarbon fuel and hydrogen fuel and generating an exhaust gas stream, a hydrocarbon fuel source and a hydrogen fuel source in fluid communication with the engine. This disclosure further provides a method for treating an exhaust gas stream, the method comprising receiving the exhaust gas stream from the engine, which includes intermittently receiving exhaust gas generated by burning hydrogen fuel, for example, during a cold start cycle. The performance of the emission treatment system can be enhanced by burning hydrogen in the engine during cycles with low exhaust gas temperatures.

[0009] This disclosure includes, but is not limited to, the following exemplary embodiments:

[0010] Example 1: An emission treatment system for treating exhaust gas from an engine burning both hydrocarbon fuel and hydrogen, the emission treatment system comprising:

[0011] An oxidation catalyst composition disposed on a substrate in fluid communication with an exhaust gas stream from an engine burning both hydrocarbon fuel and hydrogen; and

[0012] Optionally, at least one selective catalytic reduction (SCR) composition is disposed downstream of the oxidation catalyst composition on a substrate; and

[0013] Optionally, at least one ternary conversion (TWC) catalyst composition is disposed on a substrate in fluid communication with the exhaust gas stream emitted from the engine that burns both hydrocarbon fuel and hydrogen.

[0014] Example 2: The emission treatment system according to Example 1, wherein the engine is configured for intermittent combustion of hydrogen.

[0015] Example 3: An emission treatment system according to Example 1 or 2, wherein the engine is configured to burn hydrogen during a cold start cycle.

[0016] Example 4: The emission treatment system according to Example 3, wherein the cold start cycle is:

[0017] (i) up to approximately 300 seconds after engine start; or

[0018] (ii) The time during which the exhaust gas temperature from the engine (i.e., the exhaust gas temperature upstream of any catalyst component of the emission treatment system) is below 300°C.

[0019] Example 5: An emission treatment system according to any one of Examples 1 to 4, wherein the engine is in fluid communication with a hydrocarbon fuel source and a hydrogen fuel source.

[0020] Example 6: An emission treatment system according to any one of Examples 1 to 5, wherein the hydrocarbon fuel source is selected from the group consisting of gasoline, diesel and compressed natural gas.

[0021] Example 7: An emission treatment system according to any one of Examples 1 to 6, wherein the hydrogen fuel source includes a hydrogen storage product, wherein the hydrogen storage product is optionally in fluid communication with a water electrolyzer.

[0022] Example 8: An emission treatment system according to any one of Examples 1 to 7, wherein at least one of the oxidation catalyst composition and the at least one TWC catalyst composition comprises a platinum group metal component dispersed on a refractory metal oxide support.

[0023] Example 9: An emission treatment system according to any one of Examples 1 to 8, wherein at least one of the oxidation catalyst composition and the at least one TWC catalyst composition comprises approximately 5 g / ft based on the volume of the substrate on which the composition is loaded. 3 Approximately 250g / ft 3 At least one platinum group metal component within the range.

[0024] Example 10: An emission treatment system according to any one of Examples 1 to 9, wherein the substrate on which the oxidation catalyst composition or at least one TWC catalyst composition is loaded is a flow-through monomer or a single-piece wall flow filter.

[0025] Example 11: An emission treatment system according to any one of Examples 1 to 10, wherein the flow-through monomer comprises ceramic, metal, composite material, fiber, or a combination thereof.

[0026] Example 12: An emission treatment system according to any one of Examples 1 to 11, wherein the substrate on which the at least one SCR composition is loaded is a flow-through monomer or single-panel wall flow filter.

[0027] Example 13: An emission treatment system according to any one of Examples 1 to 12, wherein the at least one SCR composition is selected from the group consisting of molecular sieves containing base metals, platinum group metal components dispersed on a refractory metal oxide support, and combinations thereof.

[0028] Example 14: The emission treatment system according to Example 13, wherein the base metal includes copper and / or iron.

[0029] Example 15: The emission treatment system according to Example 13 or 14, wherein the molecular sieve is an 8-membered ring or 10-membered ring small-pore molecular sieve.

[0030] Example 16: An emission treatment system according to any one of Examples 13 to 15, wherein the molecular sieve is a zeolite having a structure selected from the group consisting of AEI, AFT, AFX, CHA, EAB, ERI, FER, KFI, LEV, SAS, SAT and SAV.

[0031] Example 17: An emission treatment system according to any one of Examples 1 to 16, wherein the molecular sieve is an aluminosilicate zeolite having a CHA crystal structure and a silicon-to-aluminum ratio of about 1 to about 1000.

[0032] Example 18: An emission treatment system according to any one of Examples 13 to 17, wherein the base metal is present in the molecular sieve at a rate of about 0.1 wt.% to about 10 wt.% based on the total weight of the molecular sieve containing the base metal.

[0033] Example 19: An emission treatment system according to any one of Examples 1 to 18, wherein the at least one SCR catalyst composition comprises about 5 g / ft based on the volume of the substrate on which the at least one SCR catalyst composition is loaded. 3 Approximately 250g / ft 3 The platinum group metals components.

[0034] Example 20: An emission treatment system according to any one of Examples 1 to 19, wherein the system does not include any other emission treatment unit besides the oxidation catalyst composition disposed on the substrate and the optional at least one SCR composition disposed on the substrate.

[0035] Example 21: An emission treatment system according to any one of Examples 1 to 20, further comprising an injector upstream of and in fluid communication with the at least one SCR composition, and said injector being configured to introduce ammonia or an ammonia precursor upstream of the at least one SCR composition.

[0036] Example 22: A combustion system for generating treated waste gas stream, comprising:

[0037] An engine that is suitable for burning both hydrocarbon fuels and hydrogen fuels and producing exhaust gas;

[0038] A hydrocarbon fuel source, which is in fluid communication with the engine;

[0039] A hydrogen fuel source, which is in fluid communication with the engine;

[0040] An oxidation catalyst composition disposed on a substrate in fluid communication with the exhaust gas stream emitted from the engine; and

[0041] Optionally, at least one selective catalytic reduction (SCR) composition is disposed downstream of the oxidation catalyst composition on a substrate; and

[0042] Optionally, at least one ternary conversion (TWC) catalyst composition is disposed on a substrate in fluid communication with the exhaust gas stream emitted from the engine.

[0043] Example 23: The combustion system according to Example 22, wherein the engine is configured for intermittent combustion of hydrogen.

[0044] Example 24: The combustion system according to Example 22 or 23, wherein the engine is configured to burn hydrogen during a cold start cycle.

[0045] Example 25: The combustion system according to Example 24, wherein the cold start cycle is:

[0046] (i) up to approximately 300 seconds after engine start; or

[0047] (ii) The time during which the exhaust gas temperature of the engine is below 300°C.

[0048] Example 26: A combustion system according to any one of Examples 22 to 25, wherein the hydrocarbon fuel source is selected from the group consisting of gasoline, diesel and compressed natural gas.

[0049] Example 27: A combustion system according to any one of Examples 22 to 26, wherein the hydrogen fuel source includes one or more of a hydrogen storage product and a water electrolyzer.

[0050] Example 28: A combustion system according to any one of Examples 22 to 27, further comprising an injector upstream of and in fluid communication with the at least one SCR composition, and the injector being configured to introduce ammonia or an ammonia precursor upstream of the at least one SCR composition.

[0051] Example 29: A method for treating waste gas flow, the method comprising:

[0052] Receive exhaust gas stream from an engine suitable for burning both hydrocarbon fuels and hydrogen fuel, wherein the receiving step includes intermittently receiving exhaust gas generated by burning the hydrogen fuel;

[0053] The waste gas stream is passed through an oxidation catalyst article comprising an oxidation catalyst composition disposed on a substrate and in fluid communication with the waste gas stream to produce a first effluent; and

[0054] Optionally, the first effluent is received into a selective catalytic reduction (SCR) article, the article comprising at least one SCR composition disposed on a substrate downstream of the oxidation catalyst article; and

[0055] Optionally, the waste gas stream is passed through at least one ternary conversion (TWC) catalyst article, the catalyst article comprising a ternary conversion catalyst composition disposed on a substrate and in fluid communication with the waste gas stream.

[0056] Example 30: The method according to Example 29, wherein intermittently receiving exhaust gas generated by burning the hydrogen fuel includes receiving exhaust gas generated by burning the hydrogen fuel during a cold start cycle.

[0057] Example 31: According to the method described in Example 30, the cold start cycle is:

[0058] (i) up to approximately 300 seconds after engine start; or

[0059] (ii) The time during which the exhaust gas temperature of the engine is below 300°C.

[0060] Example 32: The method according to any one of Examples 29 to 31, wherein the engine is in fluid communication with a hydrocarbon fuel source and a hydrogen fuel source.

[0061] Example 33: The method according to any one of Examples 29 to 32, wherein the hydrocarbon fuel source is selected from the group consisting of gasoline, diesel and compressed natural gas.

[0062] Example 34: The method according to any one of Examples 29 to 33, wherein the hydrogen fuel source includes a hydrogen storage product, wherein the hydrogen storage product is optionally in fluid communication with a water electrolyzer.

[0063] Example 35: The method according to any one of Examples 29 to 34, wherein the method further comprises forming hydrogen fuel by water electrolysis.

[0064] In some alternative embodiments of this disclosure, the oxidation catalyst composition disposed on a substrate in fluid communication with the exhaust gas stream from an engine burning both hydrocarbon fuels and hydrogen can be replaced by a TWC catalyst composition disposed on a substrate in fluid communication with the exhaust gas stream from an engine burning both hydrocarbon fuels and hydrogen. As a non-limiting example, in some alternative embodiments, this disclosure provides an emission treatment system for treating exhaust gas streams from an engine burning both hydrocarbon fuels and hydrogen, the emission treatment system comprising:

[0065] A TWC catalyst composition disposed on a substrate in fluid communication with an exhaust gas stream from an engine burning both hydrocarbon fuel and hydrogen; and

[0066] Optionally, at least one selective catalytic reduction (SCR) composition is disposed on a substrate downstream of the TWC catalyst composition.

[0067] These and other features, aspects, and advantages of this disclosure will be understood by reading the following detailed description together with the accompanying drawings, which are briefly described below. This disclosure includes any combination of two, three, four, or more of the above embodiments, and any combination of two, three, four, or more features or elements set forth in this disclosure, regardless of whether such features or elements are explicitly combined in the specific embodiments described herein. This disclosure is intended to be understood holistically such that, unless the context clearly indicates otherwise, any separable features or elements of this disclosure in any of its aspects and embodiments should be considered composable. Attached Figure Description

[0068] To provide an understanding of non-limiting embodiments of this disclosure, reference is made to the accompanying drawings, which are not necessarily drawn to scale, and the reference numerals in the drawings refer to components of exemplary embodiments of this disclosure. The drawings are merely illustrative and should not be construed as limiting.

[0069] Figure 1 This is a schematic diagram of a combustion system according to an embodiment of the present disclosure.

[0070] Figure 2A This is a perspective view of a honeycomb substrate that may include a catalyst support coating composition according to the present disclosure.

[0071] Figure 2B It is relative to Figure 2A Magnify and along parallel Figure 2A A partial cross-sectional view taken from the plane of an end face of the substrate, illustrating an embodiment in which the substrate is a flow-through substrate. Figure 2A An enlarged view of the multiple airflow channels shown in the image.

[0072] Figure 3 It is relative to Figure 2A Enlarged sectional view of the section, in which Figure 2A The honeycomb substrate in the image represents a wall-flow filter.

[0073] Figure 4 The emissions results associated with each experimental run described in Example 1 after the DOC catalyst are graphically shown, comparing the injection of hydrogen into the emissions treatment system with the use of hydrogen as fuel during the cold start cycle.

[0074] Figure 5 The SCR inlet temperature for each experimental run described in Example 1 is shown graphically.

[0075] Figure 6 The additional emissions results associated with each experimental run described in Example 1 following the DOC+SCR catalyst system are graphically shown, comparing the injection of hydrogen into the emissions treatment system with the use of hydrogen as fuel during the cold start cycle.

[0076] Figure 7 The inlet temperature of the emission treatment system used for a conventional engine (without hydrogen fuel or hydrogen injection) is compared graphically with two instances of using hydrogen as fuel during a cold start cycle.

[0077] Figure 8 The SCR inlet temperature for a conventional engine (without hydrogen fuel or with hydrogen injection) is compared graphically with two instances of using hydrogen as fuel during a cold start cycle.

[0078] Figure 9 The emissions results associated with each experimental run described in Example 2 are illustrated graphically, comparing the use of hydrogen as fuel under two different exhaust gas temperature conditions during the cold start cycle. Detailed Implementation

[0079] Non-limiting embodiments of this disclosure will be described more fully below. However, the disclosed subject matter may be implemented in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to make this disclosure thorough and complete, and to fully convey the scope of this disclosure to those skilled in the art. Unless the context clearly requires otherwise, the singular forms “a / an” and “the” as used in this specification and claims include plural indicators.

[0080] The articles, systems, and methods described herein are suitable for treating exhaust gas streams from mobile emission sources, such as vehicles. They are also suitable for treating exhaust gas streams from stationary sources, such as power plants.

[0081] definition:

[0082] In the waste gas treatment method described herein, the waste gas flows through the product or treatment system by entering at an upstream end and exiting at a downstream end. As used herein, the “inlet” end of the substrate is synonymous with the “upstream” end or “front” end. As used herein, the “outlet” end is synonymous with the “downstream” end or “rear” end. The substrate will have length and diameter.

[0083] As used herein, the term "vehicle" means, for example, any vehicle having an internal combustion engine (e.g., the combustion system of this disclosure), such as a passenger car, sport utility vehicle, van, minivan, truck, bus, garbage truck, freight truck, engineering vehicle, heavy equipment, military vehicle, or tractor.

[0084] Generally, as used herein, the term “effective” means, for example, about 35% to 100% effective, such as about 40%, about 45%, about 50%, about 55% to about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, or about 95% effective, with respect to the defined catalytic activity or storage / release activity, by weight or molar.

[0085] As used herein, the term "exhaust stream" or "exhaust gas stream" refers to any combination of flowing gases that may contain solid or liquid particulate matter. The stream includes gaseous components and is, for example, the exhaust gas of a lean-burn engine, which may contain certain non-gaseous components such as droplets, solid particles, etc. For example, the exhaust gas stream of a lean-burn engine typically further includes combustion products, products of incomplete combustion, nitrogen oxides, combustible and / or carbonaceous particulate matter (soot), and unreacted oxygen and / or nitrogen.

[0086] As used herein, the term "substrate" refers to a monolithic material on which a catalyst composition, such as a catalytic coating, is disposed. In some embodiments, the substrate is a flow-through monomer or a monolithic wall-flow filter.

[0087] As used herein, the term "catalyst" refers to a material that facilitates a chemical reaction. A catalyst comprises a "catalytically active material" and a "support" on which the active material is carried or loaded. For example, molecular sieves containing zeolites are used as supports for, for example, copper-active catalysts. Similarly, refractory metal oxide particles can be used as supports for, for example, platinum group metal catalysts.

[0088] As used herein, the term "adsorbent" refers to the substance desired for adsorption and / or absorption, i.e., NO. xMaterials containing CO and / or HC and / or NH3. The adsorbent can advantageously adsorb and / or absorb (store) substances at a certain temperature and desorb (release) said substances at a higher temperature.

[0089] As used herein, the term "functional article" means an article comprising a substrate on which a functional coating composition, particularly a catalyst and / or adsorbent coating composition, is disposed.

[0090] Catalytically active substances are also referred to as "promoters" in this paper because they promote chemical reactions. For example, the copper-containing molecular sieves in this paper may be referred to as copper-promoted molecular sieves. "Promoted molecular sieves" refer to molecular sieves in which catalytically active substances are intentionally added.

[0091] As used herein, “platinum group metal composition” refers to one of the platinum group metals (PGMs) or their oxides. The platinum group metals (PGMs) are the six metals in groups 9, 10, and 11 of the periodic table, including Rh, Pd, Ag, Ir, Pt, and Au. “Rare earth metal composition” refers to one or more oxides of the lanthanides as defined in the periodic table, including lanthanum, cerium, praseodymium, and neodymium.

[0092] Any ranges listed in this document include end values. The term “approximately” used throughout the document is used to describe and explain small fluctuations. For example, “approximately” may mean that a value can be modified by ±5%, ±4%, ±3%, ±2%, ±1%, ±0.5%, ±0.4%, ±0.3%, ±0.2%, ±0.1%, or ±0.05%. All numerical values ​​are modified by the term “approximately”, whether explicitly stated or not. Numerical values ​​modified by the term “approximately” contain a specific identifying value. For example, “approximately 5.0” contains 5.0.

[0093] Unless otherwise indicated, all parts and percentages are by weight. If not otherwise indicated, weight percentages (wt.%) are based on the whole composition free of any volatiles, that is, on the dry solids content.

[0094] All U.S. patent applications, published patent applications, and patents cited in this article are incorporated herein by reference in their entirety.

[0095] This disclosure provides an emission treatment system suitable for use with a dual-fuel engine, and a related method for treating exhaust gases from such engines. This document also provides a combustion system comprising a dual-fuel engine operating using both hydrocarbon and hydrogen fuels. In some embodiments, this disclosure provides a combustion system for generating a treated exhaust gas stream, comprising:

[0096] An engine that is designed to burn fuel sources including hydrocarbon fuels and hydrogen fuels and produce exhaust gas streams;

[0097] A hydrocarbon fuel source, which is in fluid communication with the engine;

[0098] A hydrogen fuel source, which is in fluid communication with the engine;

[0099] An oxidation catalyst composition disposed on a substrate in fluid communication with the exhaust gas stream emitted from the engine; and

[0100] Optionally, at least one selective catalytic reduction (SCR) composition is disposed downstream of the oxidation catalyst composition on a substrate; and

[0101] Optionally, at least one ternary conversion (TWC) catalyst composition is disposed on a substrate in fluid communication with the exhaust gas stream emitted from the engine.

[0102] The emission treatment system includes an oxidation catalyst downstream of an exhaust gas source, such as an engine, and in fluid communication with the exhaust gas stream, and optionally further includes a selective catalytic reduction (SCR) catalyst downstream of the oxidation catalyst. In some embodiments, the performance of the emission treatment system is improved by intermittently burning hydrogen fuel in a dual-fuel engine, particularly during cycles with low exhaust gas temperatures (e.g., during cold start cycles). When hydrogen is burned as fuel during cold start cycles (H2 + O2 → H2O), the heat of combustion can be used to increase the exhaust gas temperature without significantly increasing pollutant emissions. In some alternative embodiments, the oxidation catalyst is replaced by a TWC catalyst.

[0103] Certain embodiments of this disclosure enable vehicle manufacturers to meet stringent emission control regulations, such as Euro-7. Furthermore, in some embodiments, it is possible to improve catalyst ignition during cold start cycles by using fewer PGMs compared to conventional emission treatment system designs that rely on higher PGM content. In some embodiments of this disclosure, it is possible to reduce the size and / or complexity of emission treatment systems without sacrificing emission treatment performance. Moreover, in some embodiments of this disclosure, the use of hydrogen fuel may generate trace amounts of hydrogen in the exhaust gas, which may help maintain PGM components in an active state (e.g., a reduced state), thereby enhancing ignition properties during cold start cycles.

[0104] Therefore, in some embodiments, this disclosure provides a combustion system for generating a treated exhaust gas stream. Non-limiting exemplary embodiments of such combustion systems are provided below. Figure 1As shown, combustion system 20 may include an engine 22 suitable for burning both hydrocarbon fuels and hydrogen fuels and producing an exhaust gas stream. Engine 22 is in fluid communication with hydrocarbon fuel source 24 and hydrogen fuel source 26. Engine 22 produces an exhaust gas stream 28 fed into an exhaust treatment system 30, which typically includes an oxidation catalyst composition disposed on a substrate 32 in fluid communication with the exhaust gas stream 28 emitted from the engine, and optionally, at least one selective catalytic reduction (SCR) composition disposed downstream of the oxidation catalyst composition on the substrate. Figure 1 The non-limiting exemplary embodiment illustrates two SCR catalyst articles. An upstream SCR catalyst article 34 comprises an SCR composition (i.e., an SCRofF component) disposed on a wall-flow filter, and a downstream SCR catalyst article 36 comprises an SCR composition disposed on a flow-through substrate. This is merely one configuration of an optional SCR catalyst portion of the system, and this disclosure covers systems without an SCR catalyst component or a single SCR catalyst component disposed on any type of substrate. As shown, the emissions treatment system 30 may also include a reducing agent injector 38 (e.g., an ammonia or ammonia precursor injector) upstream of the SCR portion of the emissions treatment system. Although not shown, the emissions treatment system may also include a TWC catalyst article, which is typically upstream of any optional SCR catalyst article and optionally serves as a replacement for the oxidation catalyst article 32.

[0105] In operation, the dual-fuel engine is configured for intermittent combustion of hydrogen. For example, the engine may be configured to burn hydrogen during a cold start cycle. The cold start cycle is defined as the period from engine ignition / start until the exhaust gases from the engine reach a temperature conducive to catalyst activity, such as about 200°C. In some cases, the cold start cycle is up to about 300 seconds after engine start (e.g., up to about 275 seconds, or up to about 250 seconds, or up to about 200 seconds, or up to about 150 seconds, or up to about 120 seconds).

[0106] Hydrocarbon fuel sources can be provided in any manner commonly used to store and deliver hydrocarbon fuels to the engine. Hydrocarbon fuel sources will typically include refillable tanks in fluid communication with the engine. Non-limiting exemplary hydrocarbon fuels include gasoline, diesel, and compressed natural gas.

[0107] Hydrogen fuel sources can be carried onto the plate in replaceable or refillable hydrogen storage products, or they can be generated on the plate via water splitting or ammonia splitting. For example, hydrogen can be stored in storage tanks or reservoirs. Hydrogen can be stored in a solid state, for example, in silicon or hydrogen storage alloys. For example, solid-state hydrogen storage is taught in U.S. Pre-license Publications Nos. 2004 / 0241507, 2008 / 0003470, 2008 / 0274873, 2010 / 0024542, and 2011 / 0236790, which are incorporated herein by reference in their entirety. Hydrogen storage alloys reversibly store hydrogen and are disclosed, for example, in U.S. Patent Nos. 5,407,761 and 6,193,929 and U.S. Pre-Publication Publication No. 2016 / 0230255, which are incorporated herein by reference in their entirety. The hydrogen storage alloy is, for example, a modified AB alloy. x Type A metal hydride (MH) alloys, in which A is generally a hydride-forming element and B is a weak or non-hydride-forming element. A is typically a larger metal atom with 4 or fewer valence electrons, and B is typically a smaller metal atom with 5 or more valence electrons. Suitable AB... x The alloys include those in which x is from about 0.5 to about 5. The alloys described herein are capable of reversibly absorbing (charging) and desorbing (discharging) hydrogen gas. AB x Type alloys include, for example, the following categories (simple examples in parentheses): AB (HfNi, TiFe, TiNi), AB2 (ZrMn2, TiFe2), A2B (Hf2Fe, Mg2Ni), AB3 (NdCo3, GdFe3), A2B7 (Pr2Ni7, Ce2Co7) and AB5 (LaNi5, CeNi5).

[0108] In some embodiments, the hydrogen fuel source may comprise the generation of hydrogen on a plate using a water electrolyzer. Such a system would typically include a replaceable or refillable water tank, optionally equipped with a membrane filter to remove cations. Water from the tank is fed into the water electrolysis system to be split into H2 and O2. An onboard battery (e.g., a 48V battery) may be used to provide the necessary power to the electrolysis. A non-limiting exemplary electrolysis system suitable for this application is the S-Series proton PEM electrolyzer, available from NEL ASA. (See also the electrolyzer systems set forth in U.S. Pre-license Publications 2013 / 0263818, 2018 / 0297841, and 2019 / 0390354, which are incorporated herein by reference.) The electrolyzer may utilize, for example, a magnetic field generated by a magnet to enhance water splitting. (See Garcés-Pineda, FA; Blasco-Ahicart, M.; Nieto-Castro, D. et al., “Direct magnetic enhancement of electrocatalytic water oxidation in alkaline media,” *Nat Energy* 4, 519-525 (2019).) A non-limiting, exemplary electrolyzer system can produce hydrogen under atmospheric conditions (e.g., 5°C to 40°C) and deliver a hydrogen pressure flow of up to 200 psig. During normal driving conditions, the engine generates sufficient electricity to recharge the battery and decompose water to produce hydrogen.

[0109] Figure 1 The reducing agent injector 38 shown can be, for example, a urea or ammonia injection product in fluid communication with the treatment system, and may include a storage tank, pump, nozzle, valve, mixing tank, etc. For example, an aqueous urea solution (or other suitable reducing agent, such as ammonia or other ammonia precursor) can be mixed with air in the mixing tank. Valves can be used to meter a precise amount of the aqueous urea solution entering the waste gas stream. The urea is converted to ammonia, which acts as a reducing agent in the SCR catalyst unit.

[0110] The SCR catalyst (typically in the form of an SCR catalyst coated on a flow-through monomer or wall-flow filter) and the oxidation catalyst (typically in the form of an oxidation catalyst coated on a flow-through monomer) are each functional articles and together comprise an exhaust gas treatment system. The treatment system is typically downstream of and in fluid communication with an internal combustion engine or other exhaust gas source. The SCR catalyst is downstream of and in fluid communication with the oxidation catalyst. For example, in some embodiments, the treatment system described herein contains only one or two functional articles; that is, a separate oxidation catalyst (e.g., for certain gasoline engine applications), and an SCR catalyst (optionally comprising a combination of two SCR catalysts) and an oxidation catalyst (e.g., for certain diesel engine applications).

[0111] Coating compositions are typically added to a substrate by forming a carrier coating. The carrier coating is formed by preparing a slurry containing a specified solid content (e.g., about 10% to about 60% by weight) of a carrier in a liquid medium, then applying the slurry to the substrate and drying and calcining it to provide a coating. If multiple coatings are applied, the substrate is dried and calcined after each layer is applied and / or after applying a large number of desired layers.

[0112] Catalyst and / or adsorbent compositions can be prepared using a binder, said binder being, for example, a ZrO2 binder derived from a suitable precursor such as zirconium oxyacetate or any other suitable zirconium precursor such as zirconium oxynitrate. The zirconium oxyacetate binder provides a coating that remains uniform and intact after thermal aging, for example, when the catalyst is exposed to temperatures of at least about 600°C, such as about 800°C and higher, and to a high water vapor environment of about 5% or higher. Other potentially suitable binders include, but are not limited to, alumina and / or silica. Alumina binders include, but are not limited to, alumina, aluminum hydroxide, and alumina hydroxyaluminate. Colloidal forms of aluminum salts and alumina may also be used. Silica binders include, but are not limited to, various forms of SiO2, including silicates and silica gel. In some embodiments, the binder composition may comprise any combination of zirconium oxide, alumina, and silica.

[0113] Oxidation catalyst composition

[0114] Oxidation catalysts are suitable for oxidizing NO in waste gas. x And / or CO and / or HC components, for example at relatively low temperatures <250°C. Suitable oxidation catalysts may include platinum group metals (PGMs) dispersed on a refractory metal oxide support.

[0115] The carrier material on which the catalytically active PGM is deposited includes, for example, refractory metal oxides that exhibit chemical and physical stability at high temperatures, such as those associated with gasoline or diesel engine exhaust gases. Exemplary metal oxides include, but are not limited to, alumina, silicon dioxide, zirconium oxide, titanium dioxide, cerium dioxide, praseodymium oxide, tin oxide, and physical mixtures or chemical combinations thereof, including atomically doped combinations and containing high surface area or active compounds, such as active alumina.

[0116] Exemplary combinations of metal oxides include, but are not limited to, silica-alumina, cerium dioxide-zirconia, praseodymium oxide-cerium dioxide, alumina-zirconia, alumina-cerium dioxide-zirconia, lanthanum oxide-alumina, lanthanum oxide-zirconia-alumina, barium oxide-alumina, barium oxide-lanthanum oxide-alumina, barium oxide-lanthanum oxide-neodymium oxide-alumina, and alumina-cerium dioxide. Exemplary aluminas include, but are not limited to, macroporous boehmite, γ-alumina, and δ / θ alumina. Useful commercial aluminas used as starting materials in exemplary processes include, but are not limited to, active aluminas, such as high-bulk-density γ-alumina, low- or medium-bulk-density macroporous γ-alumina, and low-bulk-density macroporous boehmite and γ-alumina.

[0117] High surface area metal oxide supports, such as alumina support materials, also known as "gamma alumina" or "active alumina," typically exhibit surface areas exceeding 60 μm. 2 / g, often up to about 200m 2 / g or higher BET surface area. Exemplary refractory metal oxides include those with a specific surface area of ​​about 50 to about 300 m². 2 High surface area γ-alumina per g. This type of activated alumina is typically a mixture of γ and δ phases of alumina, but may also contain significant amounts of η, κ, and θ alumina phases. As used herein, “BET surface area” generally refers to the Brunauer, Emmett, Teller method for determining surface area by N₂ adsorption. In some embodiments, the specific surface area of ​​the activated alumina is from about 60 to about 350 m² / g. 2 / g, for example, about 90 to about 250m 2 / g.

[0118] In some embodiments, the metal oxide support that can be used in the catalyst composition disclosed herein is, for example, a doped alumina material such as Si-doped alumina material (including but not limited to 1% to 10% SiO2-Al2O3), a doped titanium dioxide material such as Si-doped titanium dioxide material (including but not limited to 1% to 10% SiO2-TiO2), or a doped zirconium oxide material such as Si-doped ZrO2 (including but not limited to 5% to 30% SiO2-ZrO2).

[0119] In some embodiments, the refractory metal oxide may be doped with one or more additional basic metal oxide materials, such as lanthanum oxide, barium oxide, strontium oxide, calcium oxide, magnesium oxide, or combinations thereof. The metal oxide dopant is typically present in an amount from about 1% to about 20% by weight of the catalyst composition. The dopant oxide material can be used to improve the high-temperature stability of the refractory metal oxide support or as an adsorbent for acidic gases such as NO2, SO2, or SO3.

[0120] Dopant metal oxides can be introduced using initial wet impregnation techniques or by adding colloidal mixed oxide particles. Doped metal oxides include, but are not limited to, barium oxide-aluminum oxide, barium oxide-zirconia, barium oxide-titanium dioxide, barium oxide-zirconia-aluminum oxide, lanthanum oxide-zirconia, etc.

[0121] Therefore, the refractory metal oxides or refractory mixed metal oxides in the catalyst composition are typically selected from (e.g., from the group consisting of): alumina, zirconium oxide, silica, titanium dioxide, cerium dioxide (e.g., bulk cerium dioxide), manganese oxide, zirconium oxide-alumina, cerium dioxide-zirconia, cerium dioxide-alumina, lanthanum oxide-alumina, barium oxide-alumina, silica, silica-alumina, and combinations thereof. Further doping with alkaline metal oxides provides additional useful refractory oxide supports, including, but not limited to, barium oxide-alumina, barium oxide-zirconia, barium oxide-titanium dioxide, barium oxide-zirconia-alumina, lanthanum oxide-zirconia, etc.

[0122] The oxidation catalyst composition may include any and any amount of the refractory metal oxides described above. For example, the refractory metal oxide in the catalyst composition may include at least about 15, at least about 20, at least about 25, at least about 30, or at least about 35 wt.% of alumina, where wt.% is based on the total dry weight of the catalyst composition. The catalyst composition may, for example, include about 10 to about 99 wt.% of alumina, about 15 to about 95 wt.% of alumina, or about 20 to about 85 wt.% of alumina.

[0123] The oxidation catalyst composition comprises, for example, about 15 wt.%, about 20 wt.%, about 25 wt.%, about 30 wt.%, about 35 wt.% to about 50 wt.%, about 55 wt.%, about 60 wt.%, about 65 wt.% or about 70 wt.% of alumina, based on the weight of the catalytic composition.

[0124] In some embodiments, the oxidation catalyst composition may include cerium dioxide, aluminum oxide, and zirconium oxide, or a doped composition thereof.

[0125] Based on the weight of the dried composition, the oxidation catalyst composition coated onto the substrate may include about 0.1 wt.%, about 0.5 wt.%, about 1.0 wt.%, about 1.5 wt.%, about 2.0 wt.% to about 3 wt.%, about 5 wt.%, about 7 wt.%, about 9 wt.%, about 10 wt.%, about 12 wt.%, about 15 wt.%, about 16 wt.%, about 17 wt.%, about 18 wt.%, about 19 wt.%, or about 20 wt.% of the PGM component.

[0126] Based on the volume of the substrate, the PGM component of the oxidation catalyst composition is, for example, about 5 g / ft. 3 Approximately 10g / ft 3 Approximately 15g / ft 3 Approximately 20g / ft 3 Approximately 40g / ft 3 Approximately 50g / ft 3 Approximately 70g / ft 3 Approximately 90g / ft 3 Approximately 100g / ft 3 Approximately 120g / ft 3 Approximately 130g / ft 3 Approximately 140g / ft 3 Approximately 150g / ft 3 Approximately 160g / ft 3 Approximately 170g / ft 3 Approximately 180g / ft 3 Approximately 190g / ft 3 Approximately 200g / ft 3 Approximately 210g / ft 3 Approximately 220g / ft 3 Approximately 230g / ft 3 Approximately 240g / ft 3 or approximately 250g / ft 3 exist.

[0127] In addition to the refractory metal oxide support and the catalytically active metal, the oxidation catalyst composition may further include any or a combination of oxides of lanthanum, barium, praseodymium, neodymium, samarium, strontium, calcium, magnesium, niobium, hafnium, gadolinium, terbium, dysprosium, erbium, ytterbium, manganese, iron, chromium, tin, zinc, nickel, cobalt, or copper.

[0128] Optionally, the oxidation catalyst unit may further include, as a separate composition layer or as part of a homogeneous mixture with the oxidation catalyst composition, NO suitable for adsorbing and / or absorbing waste gas. xAdsorbent compositions comprising CO and / or HC components. Suitable adsorbents include, but are not limited to, materials such as alkaline earth metal oxides, alkaline earth metal carbonates, rare earth oxides, and molecular sieves. Includes, for example, oxides or carbonates of Mg, Ca, Sr, or Ba and / or oxides of Ce, La, Pr, or Nd. Adsorbent molecular sieves include, but are not limited to, zeolites.

[0129] In some embodiments, the adsorbent comprises a molecular sieve. The molecular sieves described herein include microporous, mesoporous, and macroporous molecular sieves, or combinations thereof. Microporous molecular sieves contain channels defined by up to eight tetrahedral atoms. Mesoporous molecular sieves contain channels defined by ten-membered rings. Macroporous molecular sieves contain channels defined by twelve-membered rings. In some embodiments, these molecular sieves are selected from H… + Macroporous molecular sieves in various forms, such as β-zeolite or clinoptilolite, are also suitable. Base metal-containing molecular sieves, including, for example, FeBeta and CuCHA, are also suitable. Other non-limiting examples of macroporous molecular sieves are those listed above, as well as ZSM-12, SAPO-37, etc.

[0130] In some embodiments, the small-pore molecular sieve is selected from (e.g., from the group consisting of): aluminosilicate molecular sieves, metal-containing aluminosilicate molecular sieves, aluminophosphate (AlPO) molecular sieves, metal-containing aluminophosphate (MeAlPO) molecular sieves, aluminosilicate (SAPO) molecular sieves, and metal-containing aluminosilicate (MeSAPO) molecular sieves, and mixtures thereof. For example, the small-pore molecular sieve is selected from (e.g., from the group consisting of): framework types ACO, AEI, AEN, AFN, AFT, AFX, ANA, APC, APD, ATT, CDO, CHA, DDR, DFT, EAB, EDI, EPI, ERI, GIS, GOO, IHW, ITE, ITW, LEV, KFI, MER, MON, NSI, OWE, PAU, PHI, RHO, RTH, SAT, SAV, SIV, THO, TSC, UEI, UFI, VNI, YUG, ZON, and mixtures or symbionts thereof. For example, small-pore molecules are screened from backbone types CHA, LEV, AEI, AFX, ERI, SFW, KFI, DDR, and ITE.

[0131] In some embodiments, mesoporous molecules are screened from (e.g., selected from the group consisting of): backbone types AEL, AFO, AHT, BOF, BOZ, CGF, CGS, CHI, DAC, EUO, FER, HEU, IMF, ITH, ITR, JRY, JSR, JST, LAU, LOV, MEL, MFI, MFS, MRE, MTT, MVY, MWW, NAB, NAT, NES, OBW, PAR, PCR, PON, PUN, RRO, RSN, SFF, SFG, STF, STI, STT, STW, SVR, SZR, TER, TON, TUN, UOS, VSV, WEI, WEN, and mixtures or symbionts thereof. For example, mesoporous molecules are screened from (e.g., selected from the group consisting of): backbone types FER, MEL, MFI, and STT.

[0132] In some embodiments, macroporous molecules are screened from (e.g., selected from the group consisting of): framework types AFI, AFR, AFS, AFY, ASV, ATO, ATS, BEA, BEC, BOG, BPH, BSV, CAN, CON, CZP, DFO, EMT, EON, EZT, FAU, GME, GON, IFR, ISV, ITG, IWR, IWS, IWV, IWW, JSR, LTF, LTL, MAZ, MEI, MOR, MOZ, MSE, MTW, NPO, OFF, OKO, OSI, RON, RWY, SAF, SAO, SBE, SBS, SBT, SEW, SFE, SFO, SFS, SFV, SOF, SOS, STO, SSF, SSY, USI, UWY, VET, and mixtures or symbionts thereof. For example, macroporous molecules are screened from (e.g., selected from groups consisting of the following): backbone types AFI, BEA, MAZ, MOR, and OFF.

[0133] For example, molecular sieves may include framework types selected from the following (e.g., from the group consisting of): AEI, β-zeolite (BEA), chabazite (CHA), zeolite Y (FAU), magnesium alkali zeolite (FER), ZSM-5 (MFI), and mordenite (MOR). Non-limiting examples of zeolites having these structures include chabazite, octahedral zeolite, zeolite Y, ultrastable zeolite Y, β-zeolite, mordenite, siliceous rock, zeolite X, and ZSM-5.

[0134] Useful molecular sieves can have octagonal pore openings and double hexacyclic secondary structural units, such as those with structural types AEI, AFT, AFX, CHA, EAB, ERI, KFI, LEV, SAS, SAT, or SAV. This includes any and all isotopic framework materials, such as SAPO, AlPO, and MeAlPO materials with the same structural types.

[0135] The 8-ring microporous molecular sieve comprises, but is not limited to, aluminosilicates, borosilicates, gallium silicates, MeAPSO, and MeAlPO. These include, for example, SSZ-13, SSZ-62, natural chalcogenide, zeolite KG, Linde D, Linde R, LZ-218, LZ-235, LZ-236, ZK-14, SAPO-34, SAPO-44, SAPO-47, ZYT-6, CuSAPO-34, CuSAPO-44, and CuSAPO-47. In some embodiments, the 8-ring microporous molecular sieve will have an aluminosilicate composition, such as SSZ-13 and SSZ-62.

[0136] In some embodiments, the 8-ring microporous molecular sieve has a CHA crystal structure and is selected from (e.g., from the group consisting of) aluminosilicate zeolites, SAPO, AlPO, and MeAlPO with a CHA crystal structure. For example, the 8-ring microporous molecular sieve with a CHA crystal structure is an aluminosilicate zeolite with a CHA crystal structure. In some embodiments, the 8-ring microporous molecular sieve with a CHA crystal structure will have an aluminosilicate composition, such as SSZ-13 or SSZ-62.

[0137] Molecular sieves can be zeolite-based or non-zeolite-based. Both zeolite and non-zeolite molecular sieves can possess a chabazite crystal structure, which is also referred to as the CHA structure by the International Zeolite Association. Chabazite-based zeolites comprise naturally occurring framework silicate minerals of the zeolite group, with an approximate molecular formula of (Ca,Na2,K2,Mg)Al2Si4O. 12.6H2O (i.e., hydrated calcium aluminum silicate). Three synthetic forms of zeolite chalcogenide are described in D.W. Breck's *Zeolite Molecular Sieves*, published in 1973 by John Wiley & Sons, which is incorporated herein by reference. The three synthetic forms reported by Breck are: zeolite KG, described by Barrer et al. in *Journal of the Chemical Society* (J. Chem. Soc.), p. 2822 (1956); zeolite D, described in British Patent No. 868,846 (1961); and zeolite R, described in U.S. Patent No. 3,030,181, all of which are incorporated herein by reference in their entirety. The synthesis of another synthetic form, zeolite chalcogenide SSZ-13, is described in U.S. Patent No. 4,544,538, which is incorporated herein by reference in its entirety. The synthesis of a synthetic form of non-zeolite molecular sieve, aluminosilicate phosphate 34 (SAPO-34), having a chabazite crystal structure, is described in U.S. Patent Nos. 4,440,871 and 7,264,789, which are incorporated herein by reference in their entirety. A method for preparing another synthetic non-zeolite molecular sieve, SAPO-44, having a chabazite structure, is described, for example, in U.S. Patent No. 6,162,415, which is incorporated herein by reference in its entirety.

[0138] The synthesized 8-ring microporous molecular sieve (e.g., having a CHA structure) can be prepared by mixing a silica source, an alumina source, and a structure-directing agent under alkaline aqueous conditions. Non-limiting examples of silica sources include various types of fumed silica, precipitated silica, and colloidal silica, as well as silanolates. Non-limiting examples of alumina sources include boehmite, pseudoboehmite, aluminum hydroxide, aluminum salts such as aluminum sulfite or sodium aluminate, and aluminum alkoxides. Sodium hydroxide is typically added to the reaction mixture. A typical structure-directing agent used in this synthesis is adamantyltrimethylammonium hydroxide, although other amines and / or quaternary ammonium salts may be substituted or added. The reaction mixture is heated in a pressure vessel under stirring to produce a crystalline product. Typical reaction temperatures are in the range of about 100°C to about 200°C, for example, about 135°C to about 170°C. Typical reaction times are from 1 hour to 30 days, and in some embodiments from 10 hours to 3 days. At the end of the reaction, the pH is optionally adjusted to 6 to 10, for example, 7 to 7.5, and the product is filtered and washed with water. Any acid can be used for pH adjustment, such as nitric acid. Optionally, the product can be centrifuged. Organic additives can be used to aid in the treatment and separation of the solid product. Spray drying is an optional step in product processing. The solid product is heat-treated in air or nitrogen. Alternatively, each gas treatment can be applied in various sequences, or a mixture of gases can be applied. Typical calcination temperatures are from about 400°C to about 850°C.

[0139] Molecular sieves having a CHA structure can be prepared, for example, according to the methods disclosed in U.S. Patent Nos. 4,544,538 and 6,709,644, which are incorporated herein by reference in their entirety.

[0140] In some embodiments, the silica-alumina ratio (SAR) of the molecular sieve may be about 1, about 2, about 5, about 8, about 10, about 15, about 20, about 25 to about 30, about 35, about 40, about 45, about 50, about 60, about 70, about 80, about 90, about 100, about 150, about 200, about 260, about 300, about 400, about 500, about 750, or about 1000.

[0141] For example, the SAR of the molecular sieves described herein may be about 5 to about 250, about 10 to about 200, about 2 to about 300, about 5 to about 250, about 10 to about 200, about 10 to about 100, about 10 to about 75, about 10 to about 60, about 10 to about 50, about 15 to about 100, about 15 to about 75, about 15 to about 60, about 15 to about 50, about 20 to about 100, about 20 to about 75, about 20 to about 60, or about 20 to about 50.

[0142] In some embodiments, the molecular sieve is, for example, porous molecular sieve particles, wherein more than 90% of the molecular sieve particles have a particle size greater than 1 μm. In some embodiments, the molecular sieve particle size has a dm of less than 80 micrometers. 50 In some embodiments, the molecular sieve particles have a di of less than 80, 70, 60, 55, 50, 45, 40, 35, 30, 25, 20, 15, or 10 micrometers. 50 In some embodiments, the molecular sieve particle size has a di of less than 50 micrometers. 50 In some embodiments, more than 95% of the molecular sieve particles have a particle size greater than 1 μm, and in more specific embodiments, more than 96% of the molecular sieve particles have a particle size greater than 1 μm, and in even more specific embodiments, the molecular sieve particle composition comprises about 96% of particles larger than 1 μm and about 85% of particles larger than 2 μm, and in highly specific embodiments, the molecular sieve particle composition comprises about 96% of particles with an average particle size within 5 μm and an average particle size greater than about 5 μm. In some embodiments, the molecular sieve particle composition comprises 96% of particles in the range of about 1 μm to 10 μm. Molecular sieves suitable for adsorption are disclosed, for example, in U.S. Pre-Publication Publication No. 2016 / 0136626 and U.S. Patent No. 9,321,042, which are incorporated herein by reference in their entirety.

[0143] Molecular sieves can exhibit high surface areas; for example, the BET surface area, as determined by DIN 66131, is at least about 400 m². 2 / g, at least about 550m 2 / g or at least about 650mg 2 / g, for example, about 400 to about 750m 2 / g or approximately 500 to approximately 750m 2 / g. The molecular sieves described in this article may have an average crystal size of about 10 nanometers to about 10 micrometers, about 50 nanometers to about 5 micrometers, or about 0.1 micrometers to about 0.5 micrometers, as determined by SEM. For example, molecular sieve crystallites may have a crystal size greater than 0.1 micrometers or 1 micrometer and less than 5 micrometers.

[0144] In some embodiments, the adsorbent is a zeolite. The zeolite may be a natural or synthetic zeolite, such as octahedral zeolite, chalcogenide, clinoptilolite, mordenite, siliceous rock, zeolite X, zeolite Y, ultrastable zeolite Y, ZSM-5 zeolite, potassium chalcogenide, or β-zeolite. The zeolite adsorbent material may have a high silica-to-alumina ratio. The zeolite may have a silica-to-alumina molar ratio of at least about 5:1, for example at least about 50:1, for example from about 5:1 to 1000:1, 50:1 to 500:1, and about 25:1 to 300:1. Suitable zeolites include, but are not limited to, ZSM, Y, and β-zeolite. HC adsorbents may include β-zeolite of the type disclosed in U.S. Patent No. 6,171,556.

[0145] The structure of aluminosilicate zeolites does not contain isomorphously substituted phosphorus or other metals in the framework. That is, "aluminosilicate zeolite" does not include aluminophosphate materials such as SAPO, AlPO, and MeAlPO, while the broader term "zeolite" includes both aluminosilicates and aluminophosphates. For the purposes of this disclosure, SAPO, AlPO, and MeAlPO materials are considered non-zeolite molecular sieves.

[0146] The functional coating providing the oxidation catalyst composition may include more than one thin adhesive layer, said layers adhering to each other and the coating adhering to a substrate.

[0147] In some embodiments, the entire coating comprises individual “coatings.” The functional coating may be “zonal,” comprising zoned functional layers. This may also be described as “lateral zoning.” For example, one layer may extend from the inlet end to the outlet end, extending approximately 10%, approximately 20%, approximately 30%, approximately 40%, approximately 50%, approximately 60%, approximately 70%, approximately 80%, or approximately 90% of the substrate length. Another layer may extend from the outlet end to the inlet end, extending approximately 10%, approximately 20%, approximately 30%, approximately 40%, approximately 50%, approximately 60%, approximately 70%, approximately 80%, or approximately 90% of the substrate length. Different coatings may be adjacent to each other and not overlap. Alternatively, different layers may overlap a portion of each other, thereby providing a third “intermediate” zone. The intermediate zone may, for example, extend from approximately 5% to approximately 80% of the substrate length, such as approximately 5%, approximately 10%, approximately 20%, approximately 30%, approximately 40%, approximately 50%, approximately 60%, or approximately 70% of the substrate length.

[0148] Different layers may extend the entire length of the substrate, or may extend a portion of the substrate, and may partially or completely cover or pad each other. Each different layer may extend from either the inlet or outlet end.

[0149] Different functional compositions may be present in each individual coating. For example, one coating may include an oxidation catalyst composition without any optional adsorbent composition, and a second layer may contain one or more optional adsorbent compositions (or consist entirely of them). Thus, discussions of different layers may correspond to any of these layers. The coating composition may include one, two, or three or more coatings. In some embodiments, one or more coatings together comprise three functional compositions.

[0150] In some embodiments, the oxidation catalyst unit is in a close-coupled position. The close-coupled position is, for example, within about 12 inches (in) from where the individual cylinder exhaust pipes are joined together (i.e., the exhaust manifold), such as about 0.5 in, about 1 in, about 2 in, about 3 in, about 4 in, about 5 in to about 6 in, about 7 in, about 8 in, about 9 in, about 10 in, about 11 in, or about 12 in.

[0151] SCR Composition

[0152] The SCR composition used in SCR articles may include one or more SCR catalyst compositions as described herein. In some embodiments, the SCR composition may be effectively operated in two different temperature ranges, for example, at a low temperature of <250°C and at a high temperature of about 250°C to about 550°C. For example, in some embodiments, the SCR coating composition includes a first SCR catalyst and a second base metal-containing molecular sieve SCR catalyst, the first SCR catalyst comprising a PGM component disposed on a refractory metal oxide.

[0153] Non-limiting exemplary SCR compositions include one or more platinum group metals disposed on a high-surface-area refractory metal oxide support, such as a high-surface-area alumina support. The PGM in the SCR composition is, for example, rhodium. In some embodiments, the PGM-based SCR catalyst is effective at temperatures ≤250°C.

[0154] Based on the weight of the dried catalyst, the SCR catalyst may comprise about 0.1 wt.%, about 0.5 wt.%, about 1.0 wt.%, about 1.5 wt.%, or about 2.0 wt.% to about 3 wt.%, about 5 wt.%, about 7 wt.%, about 9 wt.%, about 10 wt.%, about 12 wt.%, about 15 wt.%, about 16 wt.%, about 17 wt.%, about 18 wt.%, about 19 wt.%, or about 20 wt.% of PGM components.

[0155] Based on the volume of the substrate, the PGM component of the catalyst is, for example, about 5 g / ft. 3 10g / ft 3 Approximately 15g / ft 3 Approximately 20g / ft 3 Approximately 40g / ft 3 or about 50g / ft 3 Approximately 70g / ft 3 Approximately 90g / ft 3 Approximately 100g / ft 3 Approximately 120g / ft 3 Approximately 130g / ft 3 Approximately 140g / ft3 Approximately 150g / ft 3 Approximately 160g / ft 3 Approximately 170g / ft 3 Approximately 180g / ft 3 Approximately 190g / ft 3 Approximately 200g / ft 3 Approximately 210g / ft 3 Approximately 220g / ft 3 Approximately 230g / ft 3 Approximately 240g / ft 3 or approximately 250g / ft 3 exist.

[0156] The SCR composition may also include a molecular sieve catalyst composition containing base metals, which is effective at higher temperatures of about 250°C to about 550°C. This catalyst will typically use injected urea as an ammonia precursor, where ammonia is the active reducing agent. In operation, urea is periodically metered into the exhaust gas stream from a location upstream of the SCR product. The injector is in fluid communication with and upstream of the SCR product. The injector is also typically associated with a reducing agent (or reducing agent precursor) storage tank and a pump.

[0157] Suitable molecular sieves are described herein with reference to the oxidation catalyst compositions. Non-limiting examples of molecular sieves have, for example, octagonal pore openings and bihexacyclic secondary structural units, such as those having the following structural types: AEI, AFT, AFX, CHA, EAB, ERI, KFI, LEV, SAS, SAT, or SAV. Included are any and all isotopic framework materials, such as SAPO, AlPO, and MeAlPO materials having the same structural type. For example, the molecular sieves described herein may each have an SAR of about 5 to about 50, for example, about 10 to about 30.

[0158] In some embodiments, the 8-ring microporous molecular sieve has a CHA crystal structure and is selected from (e.g., from the group consisting of) aluminosilicate zeolites, SAPO, AlPO, and MeAlPO with a CHA crystal structure. In some embodiments, the 8-ring microporous molecular sieve with a CHA crystal structure is an aluminosilicate zeolite with a CHA crystal structure. In some embodiments, the 8-ring microporous molecular sieve with a CHA crystal structure will have an aluminosilicate composition, such as SSZ-13 or SSZ-62.

[0159] The base metals contained in the molecular sieve catalyst compositions of this article are, for example, copper or iron, or mixtures thereof. The copper- and iron-containing chalcogenides are referred to herein as CuCHA and FeCHA.

[0160] Copper or iron is present in the ion exchange sites (pores) of the molecular sieve and may also bind to the molecular sieve, but not "in" the pores. For example, during calcination, unexchanged copper salts are decomposed into CuO, also referred to herein as "free copper" or "soluble copper." In some embodiments, free copper may be as disclosed in U.S. Patent No. 8,404,203, which is incorporated herein by reference in its entirety. The amount of free copper may be less than, equal to, or greater than the amount of ion-exchanged copper.

[0161] Copper- or iron-containing molecular sieves are, for example, obtained from, Na-containing molecules via ion exchange. + Molecular sieves (Na + Preparation (in form). Na + The "form" typically refers to the calcined form without any ion exchange. In this form, the molecular sieve usually contains Na at the exchange sites. + and H + A mixture of cations. Na + The fraction of sites occupied by cations varies depending on the specific zeolite batch and formulation. Optionally, the alkali metal molecular sieve is passed through NH4... + Exchange and NH4 + This form is used for ion exchange with copper or iron. Optionally, NH4+ is used. + The exchanged molecular sieve was calcined into H + In this form, it can also be used for ion exchange with copper or iron cations.

[0162] In some embodiments, copper or iron undergoes ion exchange with copper or iron salts to form a compound containing alkali metals and NH4. + or H + Molecular sieves in the form of copper acetate, copper sulfate, ferric chloride, ferric acetate, ferric nitrate, ferric sulfate, etc., are disclosed, for example, in U.S. Patent No. 9,242,238, which is incorporated herein by reference in its entirety. For example, Na... + NH4 + or H + Molecular sieves are mixed with a brine solution and stirred at an elevated temperature for a suitable time. The slurry is filtered, and the filter cake is washed and dried.

[0163] Iron addition includes, for example, ion exchange processes, iron salt impregnation, or mixing of molecular sieves with iron oxide. Suitable iron-containing molecular sieves are disclosed, for example, in U.S. Patent No. 9,011,807, which is incorporated herein by reference in its entirety.

[0164] The amount of base metal in the molecular sieve, based on the total weight of the metal-containing molecular sieve, is, for example, about 0.1, about 0.3, about 0.5, about 0.7, about 1.0 or about 1.5 to about 3.0, about 4.0, about 5.0, about 6.0, about 7.0, about 8.0, about 9.0 or about 10 wt.%. The amount of base metal is measured and reported as oxides.

[0165] In some embodiments, the base metal-containing molecular sieve is present on the substrate at, for example, the following loading (concentration): about 0.3 g / in. 3 Approximately 4.5 g / in 3 or approximately 0.4 g / in 3 Approximately 0.5g / in 3 Approximately 0.6g / in 3 Approximately 0.7g / in 3 Approximately 0.8g / in 3 Approximately 0.9g / in 3 Or approximately 1.0 g / in 3 Approximately 1.5 g / in 3 Approximately 2.0g / in 3 Approximately 2.5g / in 3 Approximately 3.0g / in 3 Approximately 3.5g / in 3 or approximately 4.0 g / in 3 This refers to the dry solids weight per volume of the substrate, such as the dry solids weight per volume of honeycomb monomers. The amount of base metal per volume will be, for example, from about 0.2% to about 10% of the values ​​mentioned above. The amount of base metal per volume is the base metal concentration. The amount of base metal-containing molecular sieve per volume is the molecular sieve concentration. The concentration is calculated based on the cross-section of the substrate or on the entire substrate.

[0166] A method for activating an iron-containing molecular sieve includes adding iron to the molecular sieve and then steam-calcining the resulting iron-containing molecular sieve powder in the presence of steam at a temperature of about 500°C to about 800°C for a period of about 20 minutes to about 12 hours, or steam-calcining in the presence of steam at a temperature of about 650°C to about 750°C for a period of about 20 minutes to about 2 hours. The steam calcination time is, for example, about 20 minutes to about 1 hour or 1.5 hours. The resulting steam-activated iron-containing molecular sieve powder can be spray-dried or air-dried.

[0167] If more than one type of SCR coating composition is used in the system, such compositions can be partitioned and have optional undercoat and / or outer coating. The configuration of the coatings is not limited. For example, two different SCR catalyst compositions can each be in a separate coating, wherein the coatings are configured in a front-to-back zone configuration or in a configuration from the proximal side of the substrate to the distal side of the substrate, or a combination thereof. Alternatively, functional compositions can be together in one coating or dispersed in some combination over two coatings.

[0168] As noted above, in some embodiments, the SCR functional coating may be "zonal," comprising zoned functional layers. This can also be described as "lateral zoning." For example, one layer may extend from the inlet end to the outlet end, extending approximately 10%, approximately 20%, approximately 30%, approximately 40%, approximately 50%, approximately 60%, approximately 70%, approximately 80%, or approximately 90% of the substrate length. Another layer may extend from the outlet end to the inlet end, extending approximately 10%, approximately 20%, approximately 30%, approximately 40%, approximately 50%, approximately 60%, approximately 70%, approximately 80%, or approximately 90% of the substrate length. Different coatings may be adjacent to each other and not overlap. Alternatively, different layers may overlap a portion of each other, thereby providing a third "intermediate" zone. The intermediate zone may, for example, extend from approximately 5% to approximately 80% of the substrate length, such as approximately 5%, approximately 10%, approximately 20%, approximately 30%, approximately 40%, approximately 50%, approximately 60%, or approximately 70% of the substrate length.

[0169] As noted above, the different layers may each extend the entire length of the substrate, or each may each extend a portion of the substrate's length, and may partially or completely cover or pad each other. Each different layer may extend from either an inlet or an outlet end. The coating composition may include one, two, or three or more coatings.

[0170] Different coatings may be in direct contact with the substrate. Alternatively, one or more "primer coatings" may be present such that at least a portion of the one or more functional coatings is not in direct contact with the substrate (but is in contact with the primer coating). One or more "outer coatings" may also be present such that at least a portion of the one or more functional coatings is not directly exposed to gas streams or the atmosphere (but is in contact with the outer coating).

[0171] Different coatings can be in direct contact with each other without an "intermediate" overlapping area. Alternatively, different coatings may not be in direct contact, with a "gap" between the two areas. In the case of a "base coat" or "top coat," the gap between the different layers is called an "intermediate layer." The base coat is the layer "below" the coatings, the top coat is the layer "above" the coatings, and the intermediate layer is the layer "between" the two coatings. The intermediate layer, base coat, and top coat may contain one or more functional compositions or may not contain any functional compositions.

[0172] TWC Composition

[0173] Exhaust gases from vehicles powered by gasoline engines operating under or near-stoichiometric air / fuel conditions are typically treated with a three-way catalytic converter (TWC), which effectively reduces nitrogen oxides (NOx) in the exhaust gases. x It removes pollutants such as carbon monoxide (CO) and hydrocarbons (HC). Typically, TWC catalysts comprise one or more platinum group metals, such as palladium and / or rhodium and optionally platinum, as well as an oxygen storage component. In some embodiments, the amount of the PGM component used in the TWC catalyst composition may be substantially the same as described above regarding oxidation catalysts.

[0174] In some embodiments, the TWC composition includes a PGM component, such as platinum (Pt), palladium (Pd), and rhodium (Rh), impregnated onto a porous support material. Pt and Pd are typically used for HC and CO conversion, while Rh is used for NO conversion. x The reduction is more efficient. Optionally, TWC may contain an oxygen storage component (OSC).

[0175] As used herein, “OSC” refers to a compound oxidation state that can react with, for example, oxygen (O2) or nitrogen oxides (NO) under oxidizing conditions. x Cerium dioxide (CeO2) is an entity that actively reacts with oxidizing agents such as carbon monoxide (CO), hydrocarbons (HC), or reducing agents such as hydrogen (H2) under reducing conditions. +4 The cerium in the sample may contain Ce when subjected to reducing conditions. +3 A portion of the valence state of a cerium atom. Certain non-restrictive exemplary OSCs are rare earth metal oxides, which refer to one or more oxides of scandium, yttrium, and the lanthanides as defined in the periodic table.

[0176] In some embodiments, the OSC consists of a single rare earth metal oxide or may include a mixture of more than one rare earth metal oxide. For example, cerium dioxide may be delivered as a mixed oxide of cerium and zirconium and / or a mixed oxide of cerium, zirconium, and neodymium. For example, praseodymium oxide may be delivered as a mixed oxide of praseodymium and zirconium, and / or a mixed oxide of praseodymium, cerium, lanthanum, yttrium, zirconium, and neodymium. In some embodiments, the OSC includes cerium dioxide, zirconium oxide, aluminum oxide, silicon dioxide, titanium dioxide, lanthanum oxide, barium oxide, praseodymium oxide, yttrium oxide, samarium oxide, gadolinium oxide, or combinations thereof. In some embodiments, the OSC includes cerium dioxide. In some embodiments, the OSC includes cerium dioxide and at least one additional rare earth metal oxide. In some embodiments, both the OSC and the PGM component are loaded on the same carrier material.

[0177] Substrate

[0178] In some embodiments, the useful substrate is three-dimensional, having a length, diameter, and volume similar to a cylinder. The shape need not conform to a cylinder. The length is an axial length defined by an inlet end and an outlet end. According to one or more embodiments, the substrate for the disclosed composition can be made of any material commonly used in the preparation of automotive catalysts and will typically include a metal or ceramic honeycomb structure. The substrate typically provides multiple wall surfaces on which a carrier coating composition is applied and adhered, thereby serving as a substrate for the catalyst composition.

[0179] The ceramic substrate can be made of any suitable refractory material, such as cordierite, cordierite-α-alumina, aluminum titanate, silicon titanate, silicon carbide, silicon nitride, zircon mullite, spodumene, alumina-silica-magnesium oxide, zirconium silicate, sillimanite, magnesium silicate, zircon, selenite, α-alumina, aluminosilicates, etc.

[0180] The substrate may also be metallic, including one or more metals or metal alloys. Metallic substrates may comprise any metallic substrate, such as those with openings or "perforations" in the channel walls. Metallic substrates can be used in various shapes, such as granules, corrugated sheets, or monolithic foams. Specific non-limiting examples of metallic substrates include heat-resistant base metal alloys, particularly those in which iron is a basic or major component. Such alloys may contain one or more of nickel, chromium, and aluminum, and the total amount of these metals may, for example, constitute at least about 15 wt% of the alloy, such as about 10 to about 25 wt% of chromium, about 1 to about 8 wt% of aluminum, and 0 to about 20 wt% of nickel, in each case by weight of the substrate. Non-limiting examples of metallic substrates include substrates having straight channels; substrates having protruding blades along axial channels to interrupt gas flow and open airflow communication between channels; and substrates having blades and perforations to enhance gas transport between channels, thereby allowing radial gas transport throughout the monomer. In particular, the metal substrate may be used in a closely coupled position in some embodiments, thereby allowing rapid heating of the substrate and correspondingly rapid heating of the catalyst composition coated therein (e.g., LT-CO oxidation catalyst composition).

[0181] Any suitable substrate for the catalysts disclosed herein can be used, such as a monolithic substrate type having fine, parallel airflow channels extending from the inlet or outlet face of the substrate through the airflow channels such that the channels are open to fluid flow (“flow-through substrate”). Another suitable substrate is of the type having a plurality of fine, generally parallel airflow channels extending along the longitudinal axis of the substrate, wherein typically each channel is blocked at one end of the substrate body, while alternating channels are blocked at opposite end faces (“wall-flow filter”).

[0182] Flow-through substrate

[0183] In some embodiments, the substrate is a flow-through substrate (e.g., a monolithic substrate comprising a flow-through honeycomb monolithic substrate). The flow-through substrate has narrow, parallel airflow channels extending from an inlet end to an outlet end of the substrate, such that the channels are open to fluid flow. The channels, following a substantially straight path from their fluid inlet to their fluid outlet, are defined by walls on which a catalytic coating is disposed, so that the gas flowing through the channels contacts the catalytic material. The airflow channels of the flow-through substrate are thin-walled channels, which can be of any suitable cross-sectional shape and size, such as trapezoidal, rectangular, square, sinusoidal, hexagonal, elliptical, circular, etc. As described above, the flow-through substrate can be ceramic or metallic.

[0184] The volume of the flow-through substrate can be, for example, about 50 inches. 3 Approximately 1200 inches 3 The cell density (inlet opening) is about 60 cells per square inch (cpsi) to about 500 cpsi or up to about 900 cpsi, for example about 200 to about 400 cpsi, and the wall thickness is about 50 to about 200 micrometers or about 400 micrometers.

[0185] Catalytic articles can be provided by applying a catalytic coating (e.g., as disclosed herein) as a carrier coating onto a substrate. Figure 2A and 2B An exemplary substrate 2 is shown in the form of a flow-through substrate coated with a catalyst composition as described herein. Reference Figure 2A The exemplary substrate 2 has a cylindrical shape and a cylindrical outer surface 4, an upstream end face 6, and a corresponding downstream end face 8, the downstream end face being identical to end face 6. A plurality of fine, parallel airflow channels 10 are formed therein in the substrate 2. Figure 2B As seen, the airflow channel 10 is formed by the wall 12 and extends from the upstream end face 6 to the downstream end face 8 through the carrier 2. The channel 10 is unobstructed to allow fluids, such as airflow, to flow longitudinally through the carrier 2 via its airflow channel 10. As in Figure 2B As can be more readily seen, the wall 12 is sized and configured such that the airflow channel 10 has a generally regular polygonal shape. As shown, the catalyst composition can be applied in multiple different layers if desired. In the illustrated embodiment, the catalyst composition consists of both a discrete underlayer 14 adhered to the wall 12 of the carrier member and a second discrete top layer 16 coated over the underlayer 14. Embodiments of this disclosure can be practiced with one or more (e.g., two, three, or four or more) layers of catalyst composition, and are not limited to this method. Figure 2B The two-layer embodiment is shown. Other non-limiting coating configurations are disclosed below, for example.

[0186] Wall-flow filter substrate

[0187] In some embodiments, the substrate is a wall-flow filter, which typically has a plurality of thin, generally parallel airflow channels extending along the longitudinal axis of the substrate. Typically, each channel is blocked at one end of the substrate body, with alternating channels blocked at opposite end faces. Such a monolithic wall-flow filter substrate may contain up to about 900 or more airflow channels (or “cells”) per square inch of cross-section, but much fewer airflow channels may be used. For example, the cell count per square inch (“cpsi”) of the substrate may be about 7 to 600, such as about 100 to 400. The cells may have rectangular, square, circular, elliptical, triangular, hexagonal, or other polygonal cross-sections.

[0188] Figure 3 This is a cross-sectional view of a section of the substrate of an exemplary monolithic wall-flow filter, showing alternating blocked and open channels (cells). Blocked or clogged ends 100 alternate with open channels 101, each opposite end being open and blocked, respectively. The filter has an inlet end 102 and an outlet end 103. Arrows passing through the porous cell wall 104 indicate that exhaust gas flows into the open cell end, diffuses through the porous cell wall 104, and exits at the open outlet cell end. The clogged end 100 impedes gas flow and promotes diffusion through the cell wall. Each cell wall will have an inlet side 104a and an outlet side 104b. The channels are surrounded by the cell walls.

[0189] The substrate of wall-flow filter products can have, for example, about 50 cm. 3 Approximately 100cm 3 Approximately 200cm 3 Approximately 300cm 3 Approximately 400cm 3 Approximately 500cm 3 Approximately 600cm 3 Approximately 700cm 3 Approximately 800cm 3 Approximately 900cm 3 or about 1000cm 3 Approximately 1500cm 3 Approximately 2000cm 3 Approximately 2500cm 3 Approximately 3000cm 3 Approximately 3500cm 3 Approximately 4000cm 3 Approximately 4500cm 3 or about 5000cm 3 The volume. Wall flow filter substrates typically have a wall thickness of about 50 micrometers to about 2000 micrometers, for example, about 50 micrometers to about 450 micrometers or about 150 micrometers to about 400 micrometers.

[0190] The walls of wall-flow filters are porous and typically have a wall porosity of at least about 50% or at least about 60% prior to the application of a functional coating, wherein the average pore size is at least about 5 micrometers. For example, in some embodiments, the wall-flow filter article substrate will have a porosity of ≥50%, ≥60%, ≥65%, or ≥70%. For example, in some embodiments, the wall-flow filter article substrate will have a wall porosity of about 50%, about 60%, about 65%, or about 70% to about 75%, about 80%, or about 85%, and an average pore size of about 5 micrometers, about 10, about 20, about 30, about 40, or about 50 micrometers to about 60 micrometers, about 70, about 80, about 90, or about 100 micrometers prior to the application of a catalytic coating. The terms "wall porosity" and "substrate porosity" have the same meaning and are interchangeable. Porosity is the ratio of pore volume to the total volume of the substrate. Pore ​​size can be determined using the ISO 15901-2 (static volume) procedure for nitrogen pore size analysis. Nitrogen pore size can be determined on a Micromeritics TRISTAR 3000 series instrument. Nitrogen pore size can also be determined using Barrett-Joyner-Halenda (BJH) calculations and 33 desorption points. Useful wall-flow filters have high porosity, allowing for high loadings of the catalyst composition during operation without excessive back pressure.

[0191] Catalytic wall-flow filters are disclosed, for example, in U.S. Patent No. 7,229,597, which is incorporated herein by reference in its entirety. This reference teaches a method for applying a catalytic coating such that the coating penetrates a porous wall, i.e., is dispersed throughout the wall. Flow-through and wall-flow substrates are also taught, for example, in PCT International Publication No. WO2016 / 070090, which is incorporated herein by reference in its entirety.

[0192] The functional coating may be on the surface of the substrate wall and / or in the pores of the filter wall, i.e., "in" and / or "on" the filter wall. Therefore, the phrase "catalytic coating disposed on the substrate" means on any surface, such as on the wall surface and / or on the pore surface. The functional coating may be on and / or in only one side of the cell wall, i.e., only on or in the inlet or outlet side. Alternatively, the functional coating may be disposed on both the inlet and outlet sides of the wall.

[0193] This article also provides a method for processing NO-containing... xA method for receiving an exhaust gas stream of CO and / or HC and / or soot, the method comprising receiving an exhaust gas stream from a dual-fuel engine into the exhaust gas treatment system described herein. In some embodiments, the exhaust gas stream is received from an upstream end into the article or system and exits from a downstream end. In some embodiments, the emission treatment system described herein can provide enhanced performance at low engine exhaust gas temperatures by using intermittent combustion of hydrogen in the engine. In particular, hydrogen combustion during cold start cycles is considered to improve the overall performance of the emission treatment system.

[0194] In some embodiments, this disclosure provides a method for treating an exhaust gas stream, the method comprising receiving an exhaust gas stream from an engine suitable for burning both hydrocarbon fuels and hydrogen fuels. The intermittently received exhaust gas comprises exhaust gas generated by burning hydrogen fuel. The exhaust gas stream is passed through an oxidation catalyst article comprising an oxidation catalyst composition disposed on a substrate in fluid communication with the exhaust gas stream, thereby producing a first effluent. Optionally, the first effluent is then received into a selective catalytic reduction (SCR) article comprising at least one SCR composition disposed on a substrate downstream of the oxidation catalyst article. As noted above, in some embodiments, this is advantageous for receiving exhaust gas generated by burning hydrogen fuel during a cold start cycle, for example, up to about 300 seconds after engine start.

[0195] The method of controlling hydrogen combustion can vary. In some embodiments, an onboard controller can simply switch the engine to hydrogen combustion during a defined period of time at engine start-up, such as the first 200 or 300 seconds (i.e., the cold start cycle). Alternatively, the controller receives certain data from a processing system used to determine the timing of hydrogen combustion. For example, one control system embodiment may receive inlet and outlet temperature data of the oxidation catalyst unit and control hydrogen combustion based on said temperature data. In some embodiments, hydrogen combustion will operate when the oxidation catalyst unit inlet temperature (i.e., the exhaust gas temperature from the engine) is less than about 300°C (e.g., less than about 275°C, less than about 250°C, or less than about 200°C) and will stop when the oxidation catalyst unit outlet temperature is above about 300°C.

[0196] Example

[0197] The use of hydrogen as fuel during the cold start cycle was compared with the use of hydrogen injection during the cold start cycle as described in PCT International Application WO2018 / 185665. The comparison was conducted using a diesel vehicle simulator equipped with a DOC+SCR emission treatment system comprising a DOC catalyst and an SCR flow-through catalyst. Each catalyst component of the tested system is described below.

[0198] DOC products

[0199] The DOC catalyst product is formed as follows. A bottom coating catalyst slurry containing milled alumina powder impregnated with Pd (0.5 wt.%), Ba (0.8 wt.%), and Pt (0.3 wt.%) is prepared, and its pH is adjusted to 4.5 to 5.0 with nitric acid. The bottom coating slurry has a solids content of 38 wt.%. A top coating slurry containing alumina / 5 wt.% Mn and Pt amine (3.3 wt.%) is prepared and milled, and its pH is adjusted to 4.5 to 5.0 with nitric acid. The top coating slurry has a solids concentration of 37 wt.%. Zeolite β (0.35 g / in) is added... 3 Add to the topcoat slurry.

[0200] A base coat slurry was applied to the entire core length of a 1"×3" honeycomb substrate with 400 cells per square inch (cpsi) using a carrier coating technique. The coated substrate was then air-dried at 120°C and calcined at 500°C for 1 hour, resulting in a yield of 1.6 g / in. 3 The topcoat slurry was applied over the entire undercoat and dried and calcined to provide a basecoat load of 2.5 g / in. 3 The total coating load and the 3 / 1 Pt / Pd weight ratio.

[0201] SCR products

[0202] A catalyst slurry containing milled CuCHA (3.3 wt.% Cu) and 5 wt.% zirconium acetate binder was prepared and applied to a substrate with a diameter of 64.4 cm using a carrier coating technique. 3 A 400 cpsi, 1" x 5" flow-through honeycomb substrate. The coated core is dried at 130°C and calcined at 550°C for 1 hour to provide 2.85 g / in. 3 Coating load.

[0203] Example 1: H2 fuel used during cold start cycles (0 to 200 and 0 to 300 seconds)

[0204] Samples were evaluated in a laboratory reactor equipped with a separate feed line for H2 / N2, acting as an H2 pulse source just before the DOC, to simulate the New European Driving Cycle (NEDC). During the first 200 or 300 seconds, a hydrogen pulse was introduced into the exhaust gas, with a hydrogen concentration of 1% in the feed gas. Hydrogen injection was performed in the H2 / N2 feed gas via a separate (non-preheated) line. The NH3 / NO2 ratio was 1% before the SCR catalyst. xNH3 was injected at a rate per second. The system was tested with 200 or 300 seconds of H2 injection before the DOC. The system was also tested for 200 and 300 seconds using an engine fueled with H2 before switching to diesel (without H2 injection in the emissions treatment system). To simplify comparisons between using H2 as fuel and injecting H2 before the DOC, the performance benefits are rooted in a reference (i.e., compared to the case without H2, i.e., 0%). Under each test condition, total hydrocarbon (THC) and carbon monoxide (CO) emissions were measured at the DOC product outlet.

[0205] The result is Figure 4 The results demonstrate that using H2 as fuel or as a cold-start performance enhancer is beneficial, and that using H2 as fuel yields a greater advantage than injecting H2 before the DOC. For example, using H2 as fuel for 200 seconds during a cold-start cycle produces a conversion benefit of over 50% on HC / CO performance compared to a reference using the same aged catalyst but without any H2. This 50% conversion benefit is approximately twice the amount that can be obtained from injecting H2 onto the DOC for the same time period (23% and 26% for HC and CO, respectively).

[0206] Given the substantial benefits observed from using H2 as fuel, an additional run should be performed during the cold start cycle using a shorter timeframe: 120 seconds instead of 200 seconds. Figure 4 As shown in the study, even when using only H2 as fuel for 120 seconds, a reduction of more than 40% in HC / CO emissions can be observed compared to the reference, indicating that less H2 fuel can be used and still helps to comply with more stringent regulations (e.g., Euro-7).

[0207] When H2 is used as fuel, no exothermic reaction is observed as in the case of direct H2 injection into the DOC. Therefore, the SCR inlet temperature will be the same for those operations using H2 as fuel and the reference (i.e., without any H2 involvement), as... Figure 5 As shown in the image.

[0208] NO was also measured from the SCR outlet for each run. x Emissions. Since the CO / HC conversion in the exhaust gas is not exothermic when using H2 fuel, the downstream SCR function has no warming benefit. However, as... Figure 6 The figure shows the total NO when using H2 as fuel. x The performance remains superior to the system using H2 injection preceding the DOC approach, indicating that residual CO / HC from the DOC reduces NO in downstream SCR. x performance.

[0209] Similarly, when using H2 fuel, NO from the DOC+SCR system x The conversion rate is almost twice as efficient as the system using H2 injection (24% vs. 13% at 200 seconds and 32% vs. 22% at 300 seconds), and both systems outperform the reference. Even with a shorter cycle time (120 seconds) when using H2 fuel, NO x The conversion rate is still 16% better than the reference and 3% better (16% to 13%) than the same system when the H2 injection duration is 200 seconds, which is more than 50% longer than the cycle when using H2 fuel.

[0210] Example 2: H2 fuel used during the cold start cycle at engine exhaust temperatures below those of a conventional engine.

[0211] Because H2 fuel has a lower latent heat energy than diesel, the DOC inlet temperature may not be the same as that of a conventional diesel engine (i.e., it should be lower) unless additional H2 fuel is used (e.g., compressed H2 feed). Assuming that no additional H2 fuel will be used during cold starts, then operation with a lower DOC inlet temperature is performed to simulate the difference in latent heat between diesel and H2.

[0212] Based on the volumetric calorific value of the hydrogen-air mixture (2.9 kJ / L) compared to conventional fuel (3.9 kJ / L), the exhaust gas temperature trajectory of the DOC inlet temperature was modified accordingly. The obtained DOC and SCR inlet temperature trajectories for the 200-second and 300-second hydrogen fuel scenarios are shown in [the table / image / image]. Figure 7 and 8 middle.

[0213] The same H2 fuel operation was performed at a lower inlet temperature, and the results compared to H2 fuel operation at a conventional engine exhaust temperature are presented in... Figure 9 The results indicate lower benefits observed compared to operation with the same EO temperature trajectory as a conventional engine. For example, using H2 fuel for 120 seconds at lower EO temperatures resulted in a 2% and 4% decrease in HC / CO conversion benefits, respectively. The largest decrease in benefits was in NO reduction during SCR (from 31% to 10%), indicating the need for rapid heating of the SCR catalyst.

[0214] Although a reduction in conversion efficiency was observed due to the lower EO temperature, a conversion efficiency comparable to the reference case was still noted. Figure 9 The absolute value shown is still higher than the case of using H2 injection before DOC (see [reference]). Figure 6For example, in a 200-second cold start cycle, at a lower EO temperature, the HC / CO / NO conversion efficiency is 55%, 55%, and 37%, respectively, while for H2 as fuel, with H2 injected before DOC, the efficiency is 30%, 34%, and 13%, respectively. Figure 6 ).

Claims

1. An emission treatment system for treating exhaust gas streams emitted from an engine burning both hydrocarbon fuel and hydrogen, said emission treatment system comprising: An oxidation catalyst composition disposed on a substrate in fluid communication with an exhaust gas stream from an engine that burns both hydrocarbon fuel and hydrogen. At least one selective catalytic reduction (SCR) composition disposed on a substrate downstream of the oxidation catalyst composition; as well as At least one ternary conversion (TWC) catalyst composition disposed on a substrate in fluid communication with the exhaust gas stream emitted from the engine burning both hydrocarbon fuel and hydrogen. The engine is configured to burn hydrogen and no hydrocarbon fuel during the cold start cycle, and no H2 is injected into the emission treatment system during the cold start cycle.

2. The emission treatment system according to claim 1, wherein the cold start cycle is: (i) at most 300 seconds after engine start; or (ii) The time during which the exhaust gas temperature of the engine is below 300°C.

3. The emission treatment system according to claim 1 or 2, wherein the engine is in fluid communication with a hydrocarbon fuel source and a hydrogen fuel source.

4. The emission treatment system according to claim 3, wherein the hydrocarbon fuel source comprises fuel selected from gasoline, diesel and compressed natural gas.

5. The emission treatment system according to claim 3, wherein the hydrogen fuel source includes a hydrogen storage product, wherein the hydrogen storage product is in fluid communication with a water electrolyzer.

6. The emission treatment system according to claim 1, wherein at least one of the oxidation catalyst composition and the at least one ternary conversion (TWC) catalyst composition comprises at least one platinum group metal component dispersed on a refractory metal oxide support.

7. The emission treatment system of claim 6, wherein at least one of the oxidation catalyst composition and the at least one ternary conversion (TWC) catalyst composition comprises 5 g / ft based on the volume of the substrate on which the composition is loaded. 3 Up to 250 g / ft 3 At least one platinum group metal component within the range.

8. The emission treatment system of claim 1, wherein the substrate on which the oxidation catalyst composition or the at least one ternary conversion (TWC) catalyst composition is loaded is a flow-through monomer or single-wall flow filter.

9. The emission treatment system of claim 8, wherein the flow-through monomer comprises ceramic, metal, composite material, fiber, or a combination thereof.

10. The emission treatment system of claim 1, wherein the substrate on which the at least one selective catalytic reduction (SCR) composition is loaded is a flow-through monomer or a single-piece wall-flow filter.

11. The emission treatment system according to claim 1, wherein the at least one selective catalytic reduction (SCR) composition is selected from molecular sieves containing base metals, platinum group metal components dispersed on refractory metal oxide supports, and combinations thereof.

12. The emission treatment system of claim 11, wherein the base metal comprises copper and / or iron.

13. The emission treatment system according to claim 11, wherein the molecular sieve is an 8-membered ring or a 10-membered ring small-pore molecular sieve.

14. The emission treatment system of claim 11, wherein the molecular sieve is a zeolite having a structure selected from AEI, AFT, AFX, CHA, EAB, ERI, FER, KFI, LEV, SAS, SAT and SAV.

15. The emission treatment system according to claim 11, wherein the molecular sieve is an aluminosilicate zeolite having a CHA crystal structure and a silicon-to-aluminum ratio of 1 to 1000.

16. The emission treatment system of claim 11, wherein the base metal is present in the molecular sieve at a rate of 0.1 wt.% to 10 wt.% based on the total weight of the molecular sieve containing the base metal.

17. The emission treatment system of claim 11, wherein the at least one selective catalytic reduction (SCR) composition comprises 5 g / ft by volume of the substrate on which the at least one selective catalytic reduction (SCR) composition is loaded. 3 Up to 250 g / ft 3 The platinum group metals components.

18. The emission treatment system of claim 1, wherein the system does not include any other emission treatment units other than the oxidation catalyst composition disposed on the substrate, the at least one selective catalytic reduction (SCR) composition disposed on the substrate, and the at least one ternary conversion (TWC) catalyst composition disposed on the substrate.

19. The emission treatment system of claim 1, further comprising an injector upstream of and in fluid communication with the at least one selective catalytic reduction (SCR) composition, and said injector being configured to introduce ammonia or an ammonia precursor upstream of the at least one selective catalytic reduction (SCR) composition.

20. A combustion system for generating a treated waste gas stream, comprising: An engine that is designed to burn fuel sources including hydrocarbon fuels and hydrogen fuels and produce exhaust gas streams; A hydrocarbon fuel source, which is in fluid communication with the engine; A hydrogen fuel source, which is in fluid communication with the engine; An oxidation catalyst composition disposed on a substrate and in fluid communication with the exhaust gas stream emitted from the engine; At least one selective catalytic reduction (SCR) composition disposed on a substrate downstream of the oxidation catalyst composition; as well as At least one ternary conversion (TWC) catalyst composition disposed on a substrate in fluid communication with the exhaust gas stream emitted from the engine. The engine is configured to burn hydrogen and no hydrocarbon fuel during the cold start cycle, and no H2 is injected into the emission treatment system during the cold start cycle.

21. The combustion system of claim 20, wherein the engine is configured for intermittent combustion of hydrogen.

22. The combustion system according to claim 20, wherein the cold start cycle is: (i) at most 300 seconds after engine start; or (ii) The time during which the exhaust gas temperature of the engine is below 300°C.

23. The combustion system of claim 20, wherein the hydrocarbon fuel source comprises a fuel selected from gasoline, diesel and compressed natural gas.

24. The combustion system of claim 20, wherein the hydrogen fuel source comprises at least one component selected from hydrogen storage products and water electrolyzers.

25. The combustion system of claim 20, further comprising an injector upstream of and in fluid communication with the at least one selective catalytic reduction (SCR) composition, and said injector being configured to introduce ammonia or an ammonia precursor upstream of the at least one selective catalytic reduction (SCR) composition.

26. A method for treating waste gas flow, the method comprising: Receive exhaust gas stream from an engine suitable for burning both hydrocarbon fuels and hydrogen fuel, wherein the receiving step includes intermittently receiving exhaust gas generated by burning the hydrogen fuel; The waste gas stream is passed through an oxidation catalyst article comprising an oxidation catalyst composition disposed on a substrate and in fluid communication with the waste gas stream to produce a first effluent; The first effluent is received into a selective catalytic reduction (SCR) article, the article comprising at least one selective catalytic reduction (SCR) composition disposed on a substrate downstream of the oxidation catalyst article; as well as The waste gas stream is passed through at least one ternary conversion (TWC) catalyst article, the catalyst article comprising a ternary conversion catalyst composition disposed on a substrate and in fluid communication with the waste gas stream. The engine is configured to burn hydrogen and no hydrocarbon fuel during the cold start cycle, and no H2 is injected into the emission treatment system during the cold start cycle.

27. The method of claim 26, wherein intermittently receiving exhaust gas generated by burning the hydrogen fuel includes receiving exhaust gas generated by burning the hydrogen fuel during a cold start cycle.

28. The method according to claim 27, wherein the cold start cycle is: (i) at most 300 seconds after engine start; or (ii) The time during which the exhaust gas temperature of the engine is below 300°C.

29. The method of claim 26, wherein the engine is in fluid communication with a hydrocarbon fuel source and a hydrogen fuel source.

30. The method of claim 29, wherein the hydrocarbon fuel source comprises a fuel selected from gasoline, diesel and compressed natural gas.

31. The method of claim 29, wherein the hydrogen fuel source comprises a hydrogen storage product, wherein the hydrogen storage product is in fluid communication with a water electrolyzer.

32. The method of claim 31, further comprising forming hydrogen fuel by water electrolysis.

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