Low-temperature NOx adsorbent with improved hydrothermal stability

Abstract

The present disclosure relates to a low-temperature NOx-absorbent (LT-NA) catalyst composition, a catalyst article, and an exhaust treatment system for treating exhaust gas, each comprising an LT-NA catalyst composition. A method for reducing NOx levels in an exhaust gas stream using the catalyst article is further provided. In particular, the LT-NA composition comprises a zeolite containing a first metal component comprising palladium, and a second metal component comprising an alkaline earth metal component, an oxide of the alkaline earth metal component, a rare earth metal component, an oxide of the rare earth metal component, or a combination thereof. The LT-NA composition exhibits increased low-temperature NOx adsorption capacity and improved hydrothermal stability.

Description

Technology Field

[0001] Cross-reference of related applications

[0002] This application claims the benefit of priority in its entirety to U.S. Provisional Application No. 62 / 845,359, filed on May 9, 2019.

[0003] Technology field

[0004] The present invention relates to nitrogen oxides (NO x The present invention relates to a composition, article, system, and method suitable for treating the exhaust gas stream of a lean burn internal combustion engine to reduce the emission of ). Background Technology

[0005] Environmental regulations regarding emissions from internal combustion engines are becoming increasingly stringent worldwide. Lean-burning engines, such as diesel engines, provide users with excellent fuel economy because they operate at a high air-to-fuel ratio under fuel-lean conditions. However, diesel engines also emit particulate matter (PM), unburned hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx). x It emits exhaust gas emissions containing ), wherein NO x Above all, it describes various chemical species of nitrogen oxides, including nitric oxide and nitrogen dioxide. NO x NO is a harmful component of air pollution. To reduce air pollution x Various methods have been used for the treatment of contained gas mixtures.

[0006] NO in the exhaust gas of lean combustion engines x An effective method to reduce NO under lean combustion engine operating conditions with an appropriate reducing agent in the presence of Selective Catalytic Reduction (SCR) catalyst components. xIt is necessary to react. The SCR process typically uses ammonia or hydrocarbons as reducing agents in the presence of atmospheric oxygen, and mainly results in the formation of nitrogen and vapor.

[0007] 4NO + 4NH3 + O2 → 4N2 + 6H2O (Standard SCR reaction)

[0008] 2NO2 + 4NH3 + O2 → 3N2 + 6H2O (Slow SCR reaction)

[0009] NO + NO2 + 2NH3 → 2N2 + 3H2O (Fast SCR reaction)

[0010] Catalysts currently used in the SCR process include molecular sieves, such as zeolites, that have been ion-exchanged with catalytic metals like iron or copper. Useful SCR catalyst components are NO at temperatures below 600°C. x It can effectively catalyze the reduction reaction of exhaust components, resulting in reduced NO even under low-load conditions typically associated with low exhaust temperatures. x The level can be achieved.

[0011] A major problem faced in the treatment of automotive exhaust streams is the so-called "cold start" period, which is the duration at the start of the treatment process when the exhaust stream and the exhaust gas treatment system are at a low temperature (i.e., below 150°C). At such low temperatures, the exhaust gas treatment system typically [treats] hydrocarbons (HC) and nitrogen oxides (NO₂). x It does not exhibit sufficient catalytic activity to effectively treat ) and / or carbon monoxide (CO) emissions. Generally, catalytic components, such as SCR catalyst components, produce NO at temperatures above 200°C. xWhile it is highly effective at converting to N2, it does not exhibit sufficient activity in low-temperature regions (<200°C), such as those found during cold starts or prolonged low-speed city driving. Using a catalyst that functions during low-temperature operation (<150°C) can help meet increasingly stringent emission regulations (e.g., Euro-7 regulations). Cold start NO x Since more than 80% of emissions consist of NO, this advanced NO x It is essential that adsorption materials possess high efficiency for NO adsorption. Therefore, such low-temperature NO x There is a significant demand for components capable of capturing and storing emissions and releasing them at high temperatures (>200°C) when downstream catalytic components (e.g., SCR catalyst components) are effective. Consequently, considerable efforts have been made to mitigate these issues.

[0012] NO during cold start x There are several ways to minimize emissions. For example, these exhaust emissions (i.e., HC, CO, and NO x Trapping systems have been developed that can store gases at low temperatures and then release them at higher temperatures once the remaining catalytic components of the treatment system reach sufficient catalytic activity. One such system is a well-known and commercially proven technology called lean NO. x It is a Lean NO Trap (LNT) catalyst. The LNT catalyst [reduces] NO under specific exhaust conditions x NO that captures x It contains adsorbent components. For example, NO x The adsorbent component may include alkaline earth elements, for example, alkaline earth metal oxides and carbonates, such as oxides of Mg, Ca, Sr, and / or Ba. Other LNT catalysts include NO oxides such as oxides of Ce, La, Pr, and / or Nd. xIt may contain rare earth metal oxides as adsorbent components. The LNT catalyst is catalytic NO x It additionally contains platinum group metal components (PGM), such as platinum, dispersed on a refractory metal oxide (e.g., alumina) support for oxidation and reduction. The LNT catalyst operates under cyclic lean (trapping mode) and rich (regeneration mode) exhaust conditions. Under lean conditions, the LNT catalyst produces NO x NO during the reaction ("trapping") x It captures and stores as inorganic nitrates (e.g., NO x If the adsorbent component is BaO or BaCO3, it is converted to Ba(NO3)2). Then NO x The adsorbent component is the captured NO x It emits, and PGM components emit NO under stoichiometric or transient rich engine operating conditions, or under lean engine operating conditions where external fuel is injected into the exhaust gas to induce rich conditions. x Reduce to N2. The transition from NO to NO2 is an efficient NO x Although it is a prerequisite for trapping; the reaction rate is very slow when the temperature is below 200℃, and this is because conventional LNT catalysts low-temperature starting NO x It makes trapping effluent inefficient. Furthermore, regenerating the LNT catalyst requires extensive purging, which reduces fuel economy, albeit minimally. Therefore, a desirable solution is NO that operates only under lean conditions. x It has absorption / release components.

[0013] Other types of NO x The adsorbent is low-temperature NO x It is an adsorbent (LT-NA), which is mainly NO x Pd ion-exchanged in zeolite is used as an adsorbent. In this case, NO xAdsorption and desorption characteristics strongly depend on the type of zeolite. Therefore, hydrothermal stability, enhanced adsorption capacity, and NO₂ are optimized to meet the requirements of specific engine applications. x LT-NA having a detachment profile is highly desirable.

[0014] The present disclosure generally describes enhanced NO under low temperature conditions x The present invention provides a composition, an article, and an exhaust treatment system comprising such articles exhibiting adsorption of NO x NO trapped at high temperatures (>200℃) when adsorbed and downstream catalytic components (i.e., SCR catalysts) become effective x NO suitable for emitting x It includes an adsorbent. NO of the present invention x The adsorption composition is desirable NO under various engine operating conditions x It provides adsorption and desorption characteristics.

[0015] Surprisingly, according to the present disclosure, doping palladium ion-exchanged zeolite with a specific metal component or metal oxide results in improved low-temperature starting NO after hydrothermal aging. x Adsorption capacity, higher NO x It has been found that when combined with a desorption temperature range and a diesel oxidation catalyst (DOC) composition, it leads to improved carbon monoxide (CO) and hydrocarbon (HC) conversion compared to an LT-NA composition that does not contain such metal components.

[0016] Accordingly, in one embodiment, a low-temperature NO comprising a zeolite containing at least a first metal component and a second metal component together. x An adsorbent (LT-NA) composition is provided, wherein the first metal component comprises palladium, and the second metal component is selected from the group consisting of an alkaline earth metal component, an oxide of an alkaline earth metal component, a rare earth metal component, an oxide of a rare earth metal component, and combinations thereof.

[0017] In some embodiments, the second metal component is an alkaline earth metal component or an oxide of an alkaline earth metal component. In some embodiments, the alkaline earth metal component comprises magnesium, calcium, strontium, barium, or oxides of magnesium, calcium, strontium, barium, or a combination thereof. In some embodiments, the second metal component is a rare earth metal component or an oxide of a rare earth metal component. In some embodiments, the rare earth metal component comprises oxides of Ce, La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, or Ce, La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu, or a combination thereof.

[0018] In some embodiments, at least a portion of the palladium is ion-exchanged in the zeolite. In some embodiments, palladium is present in an amount of about 0.01 weight% to about 10 weight% based on the weight of the zeolite and calculated as elemental palladium.

[0019] In some embodiments, the second metal component is present in a weight ratio to the first metal component of about 0.1 to about 2, calculated as metal for the second metal component. In some embodiments, the second metal component is present in an amount of about 0.1 weight% to about 10 weight% based on the total weight of the zeolite and calculated as metal.

[0020] In some embodiments, the zeolite is an aluminosilicate zeolite having a silica-to-alumina ratio (SAR) of about 5 to about 100. In some embodiments, the aluminosilicate zeolite has an SAR of about 10 to about 40.

[0021] 일부 실시형태에서, 제올라이트는 ABW, ACO, AEI, AEL, AEN, AET, , AFI, AFN, AFO, AFR, AFS, AFT, AFX, AFY, AHT, APC, APT, ASV, ASV, ASV ATT, ATV, AVL, AWO, AWW, BCT, BEA, BEC, BIK, BOF, BOG, BOZ, BPH, BRE, BSV, CAN, CAS, CDO, CFI, CGF, CGS, CHA, CHI, CLO, CON, CZP, DAC, DDR, DFO, DFT, DON, EDI, EMT, EPION, EPION, EPION ERI, ESV, ETR, EUO, EZT, FAU, FER, GIS, GME, GON, GOO, HEU, IFR, IFY, IHW, IMF, IRN, ISV, ITE, ITG, ITH, ITW, IWR, IWS, IWV, IWW, JBW, JRY, JSR, JSR, LFI, LAUST, LAUST, LEV, LEV LTF, LTL, LTN, MAZ, MEI, MEL, MER, MFI, MFS, MON, MOR, MOZ, MRE, MSE, , MTF, MTT, MVY, MTW, MWF, MWW, NAB, NAT, NES, NPO, NPT, NSI, OBW, OFF, OKO, OSO, PA, OSI, PAR, OWE, OWE, PPCR PON, PUN, RHO, RON, RRO, RSN, RTE, RTH, RWR, RWY, SAF, SAO, SAS, SAT, SAV, SBE, SBS, SBT, SCO, SEW, SFE, SFF, SFG, SFH, SFN, SFO, SFS, SFS, SFW, SGF, SIV, SOF, SOF, SOS, STF, STF, STO, STO STT, STW, SVR, SZR, TER, THO, TON, TSC, TUN, UEI, UFI, UOS, USI, UTL, UWY, VET, VFI, VNI, VSV, WIE, WEN, YUG, ZONE,It has a skeletal structure type selected from the group consisting of and mixtures or intergrowths thereof. In some embodiments, the zeolite has a skeletal structure type selected from the group consisting of BEA, CHA, FER, MFI, and FAU. In some embodiments, the zeolite is selected from the group consisting of beta zeolite, cabazite, ferrierite, mordenite, ZSM-5, and zeolite Y. In some embodiments, the zeolite is ferrierite.

[0022] In some embodiments, the LT-NA composition removes NO present in the exhaust gas stream from the exhaust gas stream at a temperature of about 30°C to about 200°C. x Based on the total amount of NO x NO in an amount of at least 30 to 100% of the theoretical amount based on a 1:1 molar ratio of / Pd x Adsorbs components.

[0023] In some embodiments, the LT-NA composition contains NO adsorbed on the LT-NA composition at a temperature of about 170°C to about 400°C. x NO in an amount of at least 50 to about 100 weight percent based on the total amount of ingredients x It releases the components back into the exhaust gas stream.

[0024] In some embodiments, the LT-NA composition is the first NO x Having an adsorption capacity value, and after hydrothermal aging at 750℃ for a period of 2 to 80 hours, the second NO x It has an adsorption capacity value; where the second NO x The adsorption capacity value is the first NO x It is equal to or greater than the adsorption capacity value. In some embodiments, the second NO x The adsorption capacity is improved compared to an LT-NA composition containing a zeolite that includes a first metal component and does not include a second metal component.

[0025] In another embodiment, an LT-NA article for treating an exhaust stream of an internal combustion engine is provided, the catalytic article comprising: a substrate having an inlet end and an outlet end defining the entire length; and a first washcoat comprising an LT-NA composition as disclosed herein disposed on at least a portion thereof.

[0026] In some embodiments, the LT-NA article further comprises a second washcoat comprising a diesel oxidation catalyst (DOC) composition disposed on at least a portion of the substrate. In some embodiments, the DOC composition comprises a platinum group metal (PGM) component supported on one or more refractory metal oxide support materials. In some embodiments, the PGM component comprises platinum and palladium. In some embodiments, the refractory metal oxide support material is gamma alumina or alumina doped with about 2% to about 10% SiO2. In some embodiments, the DOC composition further comprises a beta zeolite substantially devoid of any PGM species.

[0027] In some embodiments, the first and second washcoats exist in a layered configuration, wherein the first washcoat is disposed directly on the substrate and the second washcoat is disposed on at least a portion of the first washcoat. In some embodiments, the first and second washcoats exist in a layered configuration, wherein the second washcoat is disposed directly on the substrate and the first washcoat is disposed on at least a portion of the second washcoat. In some embodiments, the first washcoat and the second washcoat are combined and disposed on the substrate as a single homogeneous layer. In some embodiments, the first and second washcoats exist in a zoned configuration, wherein the first washcoat is disposed on the catalyst substrate from the inlet end for a length of about 10% to about 70% of the total length; and the second washcoat is disposed on the catalyst substrate from the outlet end for a length of about 30% to about 90% of the total length.

[0028] In some embodiments, the substrate includes a honeycomb substrate in the form of a wall-flow filter or a flow-through substrate.

[0029] In another embodiment, an exhaust gas treatment system comprising the LT-NA article disclosed herein is provided, which is positioned downstream of an internal combustion engine and fluidly connected thereto.

[0030] In some embodiments, the exhaust gas treatment system is lean NO x Lean Trap (LNT), Selective Catalytic Reduction (SCR) catalyst, ammonia or ammonia precursor injection component, Catalytic Soot Filter (CSF), or Ammonia Oxidation (AMO x It additionally includes one or more of the catalysts.

[0031] In another embodiment, NO in the exhaust gas stream from an internal combustion engine x A method for reducing the level is provided, the method comprising contacting an exhaust gas stream with an LT-NA article as disclosed herein or with an exhaust gas treatment system as disclosed herein. In some embodiments, the contacting step comprises the step of continuously passing the exhaust gas stream to contact the LT-NA article—the exhaust gas stream being at an initial temperature of about 150°C or lower and gradually heated during additional engine operation—; and removing NO from the exhaust gas stream until the exhaust gas stream reaches a predetermined temperature. x Step of adsorbing and storing - where NO x is released into the exhaust gas stream exiting the LT-NA article -; and as the temperature of the exhaust gas stream increases and these downstream catalytic materials are heated to an operating temperature of about 200°C to about 450°C, respectively, No x The method includes the step of continuously passing an exhaust gas stream exiting the LT-NA component to come into contact with at least one downstream catalytic material for the removal of components.

[0032] In another embodiment, NO of the LT-NA composition x Adsorption / Desorption Profiles and NO of LT-NA Composition x A method for controlling one or both of a desorption temperature range is provided, wherein the LT-NA composition comprises a zeolite comprising a first metal component and a second metal component, wherein the first metal component comprises palladium, and the second metal component is selected from the group consisting of an alkaline earth metal component, an oxide of an alkaline earth metal component, a rare earth metal component, an oxide of a rare earth metal component, and combinations thereof, and the method comprises selecting the second metal component and its loading. In some embodiments, NO x The desorption temperature range is about 150, about 175, about 200, about 225, or about 250 to about 275, about 300, about 325, about 350, or about 400°C.

[0033] The above and other features, aspects, and advantages of the present disclosure will become apparent by reading the following detailed description together with the accompanying drawings, which are briefly described below. The present invention includes any combination of two, three, four, or more of the embodiments mentioned above, as well as any combination of two, three, four, or more features or elements presented in the present disclosure, regardless of whether such features or elements are explicitly combined in the description of specific embodiments herein. The present disclosure is intended to be read holistically so that any separable feature or element of the invention disclosed in various aspects and embodiments is intended to be combinable, unless the context clearly indicates otherwise. Other aspects and advantages of the present invention will become apparent from the following. Brief explanation of the drawing

[0034] To provide an understanding of the embodiments of the present invention, reference is made to the accompanying drawings, wherein reference numerals denote components of exemplary embodiments of the present invention. The drawings are merely illustrative and should not be construed as limiting the present invention. The disclosures described herein are illustrated in the accompanying drawings as examples rather than limitations. For the sake of simplicity and clarity of the drawings, the features depicted in the drawings are not necessarily drawn to scale. For example, the dimensions of some features may be exaggerated compared to others for clarity. Additionally, where deemed appropriate, reference labels are repeated in the drawings to indicate corresponding or similar elements. FIG. 1a is a catalyst according to the present disclosure (i.e., low-temperature NO x A perspective view of a honeycomb-shaped substrate that may include an adsorbent washcoat composition; FIG. 1b is a partial cross-sectional view taken along a plane parallel to the end surface of the substrate of FIG. 1a, enlarged compared to FIG. 1a, and shows an enlarged view of a plurality of gas flow passages illustrated in FIG. 1 in an embodiment where the substrate is a perforated substrate; FIG. 2 is a cross-sectional view enlarged compared to FIG. 1a, wherein the honeycomb-shaped substrate of FIG. 1a represents a wall-flow type filter; FIG. 3a is a cross-sectional view of an embodiment of a zoned catalyst article of the present disclosure; FIG. 3b is a cross-sectional view of an embodiment of a stacked catalyst article of the present disclosure; FIG. 3c is a cross-sectional view of another embodiment of a stacked catalyst article of the present disclosure; FIG. 4 is a schematic diagram of an embodiment of an exhaust gas treatment system comprising an LT-NA article of the present disclosure combined with additional exhaust treatment system components; FIG. 5 is a NO for an embodiment of the present disclosure x It is a plot of adsorption and desorption versus time and temperature; FIG. 6 is a NO for an embodiment of the present disclosure xIt is a bar graph illustrating the removal capacity; FIG. 7 is a NO for an embodiment of the present disclosure x It is a plot of adsorption and desorption versus time and temperature; FIG. 8 shows NO during FTP cold-start condition for an embodiment of the present disclosure. x It is a bar graph illustrating adsorption efficiency; FIG. 9 is a plot of total hydrocarbon conversion rate versus time and temperature for an embodiment of the present disclosure; FIG. 10 is a CO-DRIFTS spectrum for an embodiment of the present disclosure; Fig. 11 is NO x It shows the effect of La concentration on the zeolite FER where the optimal effect on adsorption capacity reaches approximately 1.4% La; higher La concentrations desorbed NO for 1200 to 1600 seconds. x Slightly increase the amount of. Specific details for implementing the invention

[0035] The present disclosure generally refers to NO x The present invention provides a composition, an article suitable for the adsorption and subsequent heat release of NO, and an exhaust gas treatment system comprising such article. In particular, such article and system provide NO at low temperatures x NO that adsorbs and is trapped at high temperatures x NO suitable for heat dissipation x It includes an adsorbent composition (LT-NA). This includes, for example, an LT-NA article at a temperature exceeding 200°C NO x It is very effective at converting to N2, but is particularly important when placed upstream of a Selective Catalytic Reduction (SCR) catalyst component that does not exhibit sufficient activity in low-temperature regions (<200°C), such as during cold starts and before urea is injected into the exhaust gas.

[0036] Now, the present invention will be described more fully below. However, the present invention may be embodied in many different forms and should not be interpreted as being limited to the embodiments presented herein; rather, these embodiments are provided so that the present disclosure is thorough and complete and sufficiently conveys the scope of the invention to those skilled in the art.

[0037] definition

[0038] In this document, singular expressions (corresponding to the English articles "a" and "an") refer to one or more than one (e.g., at least one) of grammatical objects. Any range cited herein is inclusive. The term "about" used throughout is used to describe and account for small variations. For example, "about" may mean a numerical value that 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 "about," whether explicitly indicated or not. Numerical values ​​modified by the term "about" include specific identified values. For example, "about 5.0" includes 5.0.

[0039] The term reduction refers to a decrease in quantity caused by any means.

[0040] The term "associated" means, for example, "mounted," "connected," or "communicated," for example, "electrically connected" or "fluidly connected," or otherwise connected in a manner to perform a function. The term "associated" may mean, for example, being directly or indirectly related through one or more other articles or elements.

[0041] "Average particle size" is synonymous with D50, meaning that half of the particle population has a particle size greater than this point and the other half has a particle size less than it. Particle size refers to primary particles. Particle size can be measured by laser light scattering techniques using a dispersion or dry powder, for example, according to ASTM method D4464. A D90 particle size distribution indicates that 90% of the particles (by quantity) have a ferret diameter smaller than a specific size, measured by scanning electron microscopy (SEM) or transmission electron microscopy (TEM) for submicron-sized particles and by a particle size analyzer for support-containing particles (micron-sized).

[0042] The term "catalyst" refers to a substance that promotes a chemical reaction. A catalyst comprises a "catalytically active species" and a "support" that supports or holds this active species. For example, a zeolite may serve as a support for, for instance, a platinum group metal (PGM) or base metal active catalyst species. Similarly, refractory metal oxide particles may serve as a support for platinum group metal catalyst species. Catalytically active species are also referred to as "promoters" because they promote chemical reactions. For example, the present PGM-containing zeolite may be referred to as a PGM-promoted zeolite. "Promoted zeolite" refers to a zeolite to which a catalytically active species has been intentionally added.

[0043] In this disclosure, the term "catalytic article" or "catalytic article" means an article comprising a substrate having a catalytic coating composition.

[0044] As used herein, "crystal size" refers to the length of one edge of a face of a crystal, preferably the longest edge, when the crystal is not needle-shaped. Direct measurement of crystal size can be performed using microscopic methods such as SEM and TEM. For example, measurement by SEM involves examining the morphology of the material at high magnification (typically 1,000x to 10,000x). The SEM method can be performed by distributing a representative portion of the zeolite powder onto a suitable mount and spreading individual particles reasonably evenly across the entire field of view at magnifications of 1,000x to 10,000x. From this population, a statistically significant sample of random individual crystals (e.g., 50 to 200) is examined, and the longest dimension of the individual crystal parallel to the horizontal line of the straight edge is measured and recorded. Particles that are clearly large polycrystalline aggregates are not included in the measurement. Based on these measurements, the arithmetic mean of the sample crystal sizes is calculated.

[0045] "CSF" refers to a catalytic soot filter that is a wall-flow monolith. The wall-flow filter consists of alternating inlet and outlet channels, where the inlet channel is blocked at the outlet end and the outlet channel is blocked at the inlet end. A stream of soot-supported exhaust gas entering the inlet channel is forced to pass through the filter wall before exiting the outlet channel. In addition to soot filtration and regeneration, the CSF can support an oxidation catalyst to oxidize CO and HC to CO2 and H2O or NO to NO2, thereby accelerating downstream SCR catalytic activity or promoting the oxidation of soot particles at lower temperatures. The SCR catalyst composition may also be directly coated onto the wall-flow filter, referred to as SCRoF.

[0046] As used herein, the term "catalytic system" refers to a combination of two or more catalysts or articles, e.g., low-temperature NO xIt refers to a combination of an adsorbent (LT-NA) and a second catalyst, which may be a DOC, LNT, or SCR catalyst article. Alternatively, the catalyst system may be in the form of a washcoat in which the two catalysts are mixed together or coated as separate layers.

[0047] As used in the detailed description and claims, the term "constituting" is intended to be an open-ended term, such as the terms "comprising" or "containing." The term "constituting" is not intended to exclude other possible articles or elements. The term "constituting" may be equivalent to "adapted."

[0048] "DOC" refers to a diesel oxidation catalyst that converts hydrocarbons and carbon monoxide in the exhaust gas of a diesel engine. Typically, a DOC comprises one or more platinum group metals, such as palladium and / or platinum; a support material, such as alumina; a zeolite for HC storage; and optionally an accelerator and / or stabilizer.

[0049] Generally, the term “effective” means, on a weight or molar basis with respect to defined catalytic activity or storage / release activity, being, for example, about 35% to 100% effective, for example, about 40%, about 45%, about 50%, or about 55% to about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, or about 95% effective.

[0050] 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 contains gaseous components, for example, the exhaust of a lean-burn engine, which may contain certain non-gaseous components such as droplets, solid particulates, etc. The exhaust gas stream of a combustion engine typically contains combustion products (CO2 and H2O), incomplete combustion products (carbon monoxide (CO) and hydrocarbons (HC)), and nitrogen oxides (NO2). xIt further comprises ), combustible and / or carbonaceous particulate matter (soot) and unreacted oxygen and nitrogen. As used herein, the terms “upstream” and “downstream” refer to the relative directions in the flow of the engine exhaust gas stream from the engine to the exhaust pipe, where the engine is upstream and the exhaust pipe and any pollution reduction articles, such as filters and catalysts, are downstream of the engine. The inlet end of the material is synonymous with the “upstream” end or “forward” end. The outlet end is synonymous with the “downstream” end or “rear” end. The upstream zone is upstream of the downstream zone. The upstream zone may be closer to the engine or manifold, and the downstream zone may be further from the engine or manifold.

[0051] "High surface area refractory metal oxide supports" specifically refer to support particles having pores greater than 20 Å and a wide pore distribution. High surface area refractory metal oxide supports, such as alumina support materials also called "gamma alumina" or "activated alumina," typically have a surface area of ​​60 square meters / gram ("m²"). 2 Exceeding / g"), often up to about 200 m 2 This represents the BET surface area of ​​the new material being greater than / g. This activated alumina may also be a mixture of the gamma and delta phases of alumina, but may also contain significant amounts of eta, kappa, and theta alumina phases.

[0052] As used herein, "impregnated" or "impregnation" refers to the penetration of a catalytic material into the porous structure of a support material.

[0053] The term "fluid-connected" is used to refer to articles located in the same exhaust line, that is, a common exhaust stream passes through articles fluid-connected to each other. Fluid-connected articles may be adjacent to each other in the exhaust line. Alternatively, fluid-connected articles may be separated by one or more articles, also referred to as "wash-coated monoliths."

[0054] In the present invention, the term "functional article" means an article comprising a substrate having a functional coating composition disposed thereon, in particular a catalyst and / or adsorbent coating composition.

[0055] As used herein, "impregnated" or "impregnation" refers to the penetration of a catalytic material into the porous structure of a support material.

[0056] "LNT" is slim NO x It refers to a trap involving platinum group metals, rare earth metal oxides, and NO during rare conditions. x It is a catalyst containing an alkaline earth metal trapping material (e.g., BaO or MgO) suitable for adsorbing NO. Under enrichment conditions, NO x It is released and reduced to nitrogen.

[0057] As used herein, the term "molecular sieve," e.g., zeolites and other zeolite framework materials (e.g., isomorphically substituted materials), refers to a material capable of supporting catalytic PGMs or other catalytic metals in the form of fine particles. A molecular sieve is a material based on an extensive three-dimensional network of oxygen ions that generally contains tetrahedral regions, has a substantially uniform pore distribution, and has an average pore size of 10 angstroms (Å) or less. Molecular sieves can be distinguished by the geometry of the pores formed primarily by a rigid network of (SiO4) / AlO4 tetrahedra. The pore entrances are formed by 6, 8, 10, or 12 ring atoms relative to the atom forming the entrance opening. A molecular sieve is a crystalline material having a fairly uniform pore size with a diameter ranging from about 3 to 10 Å, depending on the type and amount of cations contained in the molecular sieve lattice and the type of molecular sieve. Molecular sieves include small-pore, medium-pore, and large-pore molecular sieves, or combinations thereof. The pore size is defined by the maximum ring size.

[0058] The terms "nitrogen oxide" or "NO" as used herein x" refers to nitrogen oxides such as NO, NO2, or N2O.

[0059] The terms “on” and “over” in relation to coating layers may be used as synonyms. The term “directly on” means direct contact. The disclosed article is referred to as comprising a coating layer “on” a second coating layer in certain embodiments, and this term is intended to include embodiments having an interposed layer in which direct contact between coating layers is not required (i.e., “on” is not equated with “directly on”).

[0060] The term "selective catalytic reduction" (SCR) as used herein refers to a catalytic process that uses a nitrogen reducing agent to reduce nitrogen oxides to nitrogen (N2).

[0061] “Substantially absent” means “almost none or none at all” or “not intentionally added at all,” and also means having only trace amounts and / or unintended amounts. For example, in certain embodiments, “substantially absent” means less than 2 wt%, less than 1.5 wt%, less than 1.0 wt%, less than 0.5 wt%, 0.25 wt%, or less than 0.01 wt% based on the weight of the total composition indicated.

[0062] As used herein, the term “substrate” refers to a monolithic material in which a catalyst composition, i.e., a catalyst coating, is typically disposed on top in the form of a washcoat. In one or more embodiments, the substrate is a perforated monolith and a monolithic wall-flow type filter. Perforated and wall-flow type substrates are also taught, for example, in International Application Publication WO2016 / 070090, which is incorporated herein by reference. The washcoat is formed by preparing a slurry containing a catalyst with a specific solid content (e.g., 30 to 90 wt%) in a liquid, and then coating this onto a substrate and drying it to provide a washcoat layer. The reference to “monolithic substrate” means a homogeneous and continuous integral structure from inlet to outlet. The washcoat is formed by preparing a slurry containing particles with a specific solid content (e.g., 20 to 90 wt%) in a liquid vehicle, and then coating this onto a substrate and drying it to provide a washcoat layer.

[0063] As used herein, the term "support" refers to any high-surface-area material to which a catalytic precious metal is applied, generally a metal oxide material.

[0064] As used herein, the term “washcoat” has a conventional meaning in the field of thin adhesive coatings of catalytic materials or other materials applied to substrate materials, such as honeycomb substrates, that are porous enough to allow the passage of a gas stream being treated. The washcoat containing the metal-promoted molecular sieve of the present invention may optionally comprise a binder selected from silica, alumina, titania, zirconia, ceria, or combinations thereof. The loading of the binder is about 0.1 to 10 weight percent based on the weight of the washcoat. As used herein and described in the literature [Heck, Ronald and Farrauto, Robert, Catalytic Air Pollution Control, New York: Wiley-Interscience, 2002, pp. 18-19], the washcoat layer comprises a compositionally distinct layer of material disposed on the surface of a monolithic substrate or the underlying washcoat layer. The substrate may include one or more washcoat layers, and each washcoat layer may differ in some way (e.g., its physical properties such as particle size or crystal phase may differ) or its chemical catalytic function may differ.

[0065] "Weight % (wt%)" refers to the total composition free of any volatile substances, i.e., the dry solids content, unless otherwise indicated. Unless otherwise indicated, all parts and percentages are by weight.

[0066] As used herein, the term "zeolite" refers to specific examples of molecular sieves that additionally contain silicon and aluminum atoms. Generally, zeolites are defined as aluminosilicates having an open three-dimensional framework structure composed of corner-shaping TO4 tetrahedra (where T is Al or Si, or optionally P). Cations that balance the charge of the anionic framework are loosely associated with framework oxygens, and the remaining pore volume is filled with water molecules. Non-framework cations are generally exchangeable, and water molecules are removable.

[0067] The aluminosilicate zeolite structure does not contain phosphorus or other metals isomorphically substituted in the framework. That is, "aluminosilicate zeolite" excludes aluminophosphate materials such as SAPO, AlPO, and MeAlPO materials, whereas the term "zeolite" in a broader sense includes aluminosilicates and aluminophosphates. For the purposes of this disclosure, SAPO, AlPO, and MeAlPO materials are considered non-zeolite molecular sieves.

[0068] The zeolite may include SiO4 / AlO4 tetrahedra that are independently bonded by common oxygen atoms to form a three-dimensional network. The molar ratio of silica to alumina ("SAR") of the zeolite may vary over a wide range, but is generally 2 or greater. For example, the zeolite may have a SAR of about 5 to about 1000.

[0069] Zeolites consist of secondary building units (SBUs) and composite building units (CBUs), which appear in many different skeletal structures. Secondary building units contain 16 or fewer tetrahedral atoms and are non-chiral. Composite building units do not need to be achiral and cannot necessarily be used to form the entire skeleton. For example, groups of zeolites have single 4-ring (s4r) composite building units in their skeletal structures. In the 4-ring, "4" indicates the positions of tetrahedral silicon and aluminum atoms, and oxygen atoms are located between the tetrahedral atoms. Other composite building units include, for example, single 6-ring (s6r) units, double 4-ring (d4r) units, and double 6-ring (d6r) units. A d4r unit is created by combining two s4r units. A d6r unit is created by combining two s6r units. There are 12 tetrahedral atoms in the d6r unit.

[0070] Typically, ABW, ACO, AEI, AEL, AEN, AET, AFI, AFN, AFO, AFR, AFS, AFT, AFX, AFY, AHT, APC, APD, ASV, ATN, ATO, ATS, ATT, ATV, AVL, AWO, AWW, BCT, BEA, BEC, BIK, BOG, BPH, BRE, CAN, CAS, SCO, CFI, SGF, CGS, CHA, CHI, CLO, CON, CZP, DAC, DDR, DFO, DFT, DON, EAB, EDI, EEI, EMT, EON, EPI, ERI, ESV, ETR, EUO, FAU, FER, GIS, GME, GON, GOO, HEU, IFR, IFY, IHW, IRN, ISV, ITE, ITH, ITW, IWR, IWW, JBW, KFI, LAU, Any skeletal type such as skeletal types of LEV, LOV, LTA, LTL, LTN, MAZ, MEI, MEL, MER, MFI, MFS, MON, MOR, MOZ, MTF, MTT, MTW, MWF, MWW, NAB, NAT, NES, NPO, NPT, NSI, OBW, OFF, OSI, OSO, OWE, PAR, PAU, PHI, PON, RHO, RON, RRO, RSN, RTE, RTH, RWR, RWY, SAO, SAS, SAT, SAV, SBE, SBS, SBT, SFE, SFF, SFG, SFH, SFN, SFO, SFW, SOS, SSY, STF, STI, STT, TER, THO, TON, TSC, UEI, UFI, USI, UTL, VET, VFI, VNI, VSV, WIE, WEN, YUG, ZON, or combinations thereof Zeolite can be used.

[0071] Zeolites are crystalline materials having a somewhat uniform pore size with a diameter ranging from about 3 to 10 angstroms, depending on the type of zeolite and the type and amount of cations contained within the zeolite lattice. The pore size is defined by the ring size. As used herein, the term “small pore” refers to a pore opening less than about 5 angstroms, for example, about 3.8 angstroms.

[0072] Small pore zeolites contain channels defined by eight or fewer tetrahedral atoms. The term "8-ring" zeolite refers to a zeolite having a cage-like structure created by connecting the double 6-ring building units with 8-ring pore openings and double 6-ring secondary building units by four rings.

[0073] Exemplary small-pore zeolites include 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 combinations thereof.

[0074] Mesoporous zeolites contain channels defined by 10-membered rings. Exemplary mesoporous zeolites include framework 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 combinations thereof.

[0075] Large pore zeolites contain channels defined by 12-membered rings. Exemplary large pore zeolites include 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 combinations thereof.

[0076] Unless otherwise indicated, all parts and percentages are by weight. "Weight % (wt%)" refers to the total composition free of any volatile substances, i.e., the dry solids content, unless otherwise indicated.

[0077] All methods described herein may be performed in any suitable order unless otherwise indicated herein or clearly contradictory in the context. Any and all examples provided herein, or the use of exemplary language (e.g., “like”), are intended merely to better describe the materials and methods and are not limited in scope unless otherwise claimed. No language in this specification shall be interpreted as indicating any unclaimed element as essential to the practice of the disclosed materials and methods.

[0078] All U.S. patent applications, prior grant publications, and patents referred to herein are incorporated herein by reference in their entirety.

[0079] Low temperature NO x Adsorbent (LT-NA) composition

[0080] The present disclosure provides an LT-NA composition comprising a zeolite containing at least a first metal component and a second metal component together, wherein the first metal component comprises palladium, and the second metal component is selected from the group consisting of an alkaline earth metal component, an oxide of an alkaline earth metal component, a rare earth metal component, an oxide of a rare earth metal component, and combinations thereof. Individual components of the LT-NA composition are further described herein below.

[0081] Zeolite

[0082] As mentioned above, the LT-NA composition comprises a zeolite containing at least a first metal component and a second metal component together. As previously stated herein, the term zeolite refers to a specific example of a molecular sieve further comprising silicon and aluminum atoms. According to one or more embodiments, the zeolite may be based on a skeletal topology that identifies the structure. Typically, ABW, ACO, AEI, AEL, AEN, AET, , AFI, AFN, AFO, AFR, AFS, AFT, AFX, AFY, AHT, APC, APD, AST, ASV, ATN, ATO, ATS, ATT, ATV, AVL, AWO, AWW, BCT, BEA, BEC, BIK, BOF, BOG, BOZ, BPH, BRE, BSV, CAN, CAS, CDO, CFI, CGF, CGS, CHA, CHI, CLO, CON, CZP, DAC, DDR, DFO, DFT, DON, EAB, EDI, EEI, EMT, EON, EPI, ERI, ESV, ETR, EUO, EZT, FAU, FER, GIS, GME, GON, GOO, HEU, IFR, IFY, IHW, IMF, IRN, ISV, ITE, ITG, ITH, ITW, IWR, IWS, IWV, IWW, JBW, JRY, JSR, JST, KFI, LAU, LEV, LOV, LTA, LTF, LTL, LTN, MAZ, MEI, MEL, MER, MFI, MFS, MON, MOR, MOZ, MRE, MSE, , MTF, MTT, MVY, MTW, MWF, MWW, NAB, NAT, NES, NPO, NPT, NSI, OBW, OFF, OKO, OSI, OSO, OWE, PAR, PAU, PCR, PHI, PON, PUN, RHO, RON, RRO, RSN, RTE, RTH, RWR, RWY, SAF, SAO, SAS, SAT, SAV, SBE, SBS, SBT, SCO, SEW, SFE, SFF, SFG, SFH, SFN, SFO, SFS,Any skeletal type of zeolite, such as SFW, SGF, SIV, SOF, SOS, SSF, SSY, STF, STI, STO, STT, STW, SVR, SZR, TER, THO, TON, TSC, TUN, UEI, UFI, UOS, USI, UTL, UWY, VET, VFI, VNI, VSV, WIE, WEN, YUG, ZON, and mixtures or combinations thereof, may be used. In some embodiments, the zeolite has a skeletal structure type selected from the group consisting of BEA, CHA, FER, MFI, and FAU.

[0083] In some embodiments, the zeolite has a two-dimensional pore system. In some embodiments, the zeolite having a two-dimensional pore system may have a framework type such as FER, CSV, DAC, HEU, MFS, MWW, NES, RRO, SFG, STI, STT, or TER, but is not limited thereto. Discussion regarding the synthesis and pore geometry of zeolites having an FER structure, for example, in the literature [Weitkamp et al., Chem. Eng. Technol . 25, (2002), 3, 273-275]; literature[Pinar et al., Proceedings of the 5 th Serbian-Croatian-Slovenian Symposium on Zeolites , 32-35]; and literature[Parikh et al., Indian Journal of Chemical Technology [, 18, Sept. 2011, 335-342] are disclosed, and the full text of each of these is incorporated herein by reference.

[0084] In some embodiments, the zeolite is an aluminosilicate zeolite. In some embodiments, the aluminosilicate zeolite crystals have an average crystal size (i.e., the average crystal size of individual crystals including twins) greater than about 0.5 μm, preferably about 0.1 μm to about 15 μm, for example, about 0.5 μm to about 5 μm, about 0.7 μm to about 1.5 μm, about 1 μm to about 5 μm, or about 1 μm to about 10 μm.

[0085] In some embodiments, the zeolite is selected from the group consisting of beta zeolite, cabazite, ferrierite, mordenite, ZSM-5, and zeolite Y. In some embodiments, the zeolite is ferrierite.

[0086] The molar ratio of silica to alumina (“SAR”) of the zeolite may vary over a wide range, but is generally 2 or greater. For example, the zeolite may have an SAR of about 5 to about 1000. In some embodiments, the zeolite has a silica to alumina ratio (SAR) of about 2 to about 300, e.g., about 5 to about 250; about 5 to about 200; about 5 to about 100; and about 5 to about 50. In one or more specific embodiments, the molecular sieve has a ratio of about 10 to about 200, about 10 to about 100, about 10 to about 75, about 10 to about 60, and about 10 to about 50; about 15 to about 100, about 15 to about 75, about 15 to about 60, and about 15 to about 50; The molecular sieve has a SAR molar ratio in the range of about 20 to about 100, about 20 to about 75, about 20 to about 60, and about 20 to about 50. In one or more embodiments, the molecular sieve has a SAR molar ratio in the range of about 1, about 2, about 5, about 8, about 10, about 15, about 20, or 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. In some embodiments, the zeolite is an aluminosilicate zeolite having a SAR of about 5 to about 100. In some embodiments, the aluminosilicate zeolite has a SAR of about 10 to about 40. In some embodiments, the molar ratio of silica to alumina (SiO2:Al2O3) is about 2 to about 50. In some embodiments, the molar ratio of SiO2 to Al2O3 is about 25.

[0087] While we do not wish to be bound by theory, a high sodium content in zeolites can have a negative effect on hydrothermal stability. Therefore, a low content of sodium and alkali metals in zeolites is generally desirable. In certain embodiments, the zeolite has an alkali content of less than 3 wt%, more preferably less than 1 wt%, and even more preferably less than 0.1 wt% based on the total weight of the calcined zeolite (reported as an alkali metal oxide based on non-volatility). In some embodiments, a zeolite with a low alkali content may be provided by ion-exchanging a zeolite in the form of sodium (Na) with an ammonia (NH4). The NH4 ion exchange into the zeolite may be performed at room temperature or at a temperature of about 80°C or lower for about 1 to 24 hours. In some embodiments, the resulting zeolite material may be dried preferably at about 100 to 120°C to provide an NH4-exchanged zeolite. In some embodiments, the NH4-exchanged zeolite may be calcined at a temperature of at least about 450°C to provide an H-exchanged zeolite.

[0088] First metal component

[0089] As mentioned above, the disclosed LT-NA composition comprises a zeolite comprising at least a first metal component and a second metal component together, wherein the first metal component comprises palladium. As used herein, the term “first metal component” refers to the first metal, or an ion or compound of the first metal, e.g., an oxide. In some embodiments, the first metal comprises palladium. As used herein, the term “comprising palladium” means that the metal component comprises or contains palladium, including palladium in a zero-valence state (i.e., palladium metal), palladium ions, or compounds thereof, or is palladium. The disclosed LT-NA composition may be described as comprising a zeolite “comprising” palladium (or comprising palladium “associated” with the zeolite). In such cases, “comprising” (or “associated”) is understood to mean that palladium is present in the ion-exchange sites of the zeolite, on the surface of the zeolite, or on both the ion-exchange sites of the zeolite and the surface of the zeolite.

[0090] The concentration of the first metal component may vary, but will typically be about 0.01 wt% to about 10 wt% with respect to the weight of the zeolite. Palladium may be present in the zeolite in amounts, based on the total weight of the zeolite, for example, about 0.1 wt%, about 0.2 wt%, about 0.5 wt%, about 0.7 wt%, about 0.9 wt%, or about 1.0 wt% to about 1.5 wt%, about 2.0 wt%, about 2.5 wt%, about 3.0 wt%, about 3.5 wt%, about 4.0 wt%, about 4.5 wt%, or about 5.0 wt%. The weight of palladium is measured and reported as metal.

[0091] Second metal component

[0092] As mentioned above, the disclosed LT-NA composition comprises a zeolite containing at least a first metal component and a second metal component together. The second metal component is selected from the group consisting of an alkaline earth metal component, an oxide of an alkaline earth metal component, a rare earth metal component, an oxide of a rare earth metal component, and combinations thereof.

[0093] In some embodiments, the second metal component exists as a metal ion that may exist, for example, within at least a portion of the ion-exchange sites of the zeolite. In some embodiments, the second metal component exists as a metal oxide.

[0094] The amount of the second metal component may vary. For example, the LT-NA composition generally contains about 0.1 wt% to about 10 wt%, or about 0.5 wt% to about 5 wt%, of the second metal component based on the total weight of the zeolite (i.e., the weight of the zeolite including the first metal component, the second metal component, and any additionally added component). In some embodiments, the total amount of the second metal component is less than 10 wt%, less than 9 wt%, less than 8 wt%, less than 7 wt%, less than 6 wt%, less than 5 wt%, less than 4 wt%, less than 3 wt%, less than 2 wt%, less than 1 wt%, or less than 0.5 wt% based on the total weight of the zeolite. In some embodiments, the second metal component is present in an amount of about 0.5 wt% based on the total weight of the zeolite. In some embodiments, the second metal component is present in an amount of about 0.5 wt%, about 1 wt%, about 2 wt%, about 3 wt%, about 4 wt%, or about 5 wt% based on the total weight of the zeolite.

[0095] In some embodiments, the second metal component is present in a weight ratio of about 0.1 to about 2 to the first metal component, calculated as each metal oxide and metal.

[0096] Alkaline earth metal components

[0097] In some embodiments, the second metal component of the LT-NA composition disclosed herein is an alkaline earth metal component. As used herein, the term “alkaline earth metal component” refers to an alkaline earth metal compound, complex, etc., which may decompose upon calcination or use of the catalyst or otherwise be converted into a form such as a corresponding alkaline earth metal oxide. In some embodiments, at least a portion of the alkaline earth metal component exists as an ion of the alkaline earth metal within the ion exchange sites of the zeolite. In some embodiments, at least a portion of the alkaline earth metal component exists as an alkaline earth metal oxide disposed on or within the zeolite. As used herein, the term “alkaline earth metal” refers to a Group II metal such as magnesium, calcium, strontium, and barium. In some embodiments, the alkaline earth metal component comprises barium, calcium, magnesium, strontium, or a mixture thereof. In some embodiments, the alkaline earth metal component is barium. In some embodiments, the alkaline earth metal component is strontium.

[0098] Alkaline earth metal components also contain oxides of alkaline earth metals.

[0099] Rare earth metal components

[0100] In some embodiments, the second metal component of the LT-NA composition disclosed herein is a rare earth metal component. The term “rare earth metal component” refers to a rare earth metal compound, complex, etc., which may decompose upon calcination or use of the catalyst or otherwise be converted into a form such as a corresponding rare earth metal oxide. In some embodiments, at least a portion of the rare earth metal component exists as an ion of the rare earth metal within the ion exchange sites of the zeolite. In some embodiments, at least a portion of the rare earth metal component exists as a rare earth metal oxide disposed on or within the zeolite. These oxides may include various oxidation states of the rare earth metal, such as monooxide, dioxide, trioxide, tetroxide, etc., depending on the valence of the specific transition metal. As used herein, the term “rare earth metal” refers to a metal of the lanthanide series as defined in the periodic table of elements. Lanthanide metals include cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. Particularly suitable rare earth metals include one or more of lanthanum, cerium, neodymium, yttrium, praseodymium, and mixtures thereof. In some embodiments, the rare earth metal component includes Y, Ce, La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, or a combination thereof. In some embodiments, the rare earth metal component is lanthanum.

[0101] While the foregoing description provides several suitable ranges or amounts for the metal components of the LT-NA composition, it should be noted that each disclosed range or amount for any one of these components may be combined with the disclosed range or amount for other components to form new ranges or sub-ranges. Such embodiments are also explicitly taken into account by the present invention.

[0102] Rare earth metal components also include oxides of rare earth metals.

[0103] Diesel Oxidation Catalyst (DOC) Composition

[0104] Generally, DOC compositions comprise one or more platinum group metal (PGM) components dispersed on a support, such as a refractory metal support. Various such DOC compositions are known to be used to treat diesel engine exhaust gases to convert both hydrocarbon (HC) and carbon monoxide (CO) gaseous pollutants into carbon dioxide and water by catalyzing the oxidation of these pollutants.

[0105] The term “PGM component” refers to any component containing PGM (e.g., Ru, Rh, Os, Ir, Pd, Pt, and / or Au). References to “PGM component” allow for the presence of PGM in any valence state. For example, PGM may be in a metallic form with a valence of zero, or PGM may be in an oxide form. Terms such as “platinum (Pt) component,” “rhodium (Rh) component,” “palladium (Pd) component,” “iridium (Ir) component,” “ruthenium (Ru) component,” etc. refer to respective platinum group metal compounds, complexes, etc., that decompose upon calcination or use of the catalyst or otherwise convert into a catalytically active form, largely a metal or a metal oxide. In some embodiments, the PGM component comprises palladium, platinum, rhodium, rhenium, ruthenium, iridium, or a combination thereof. In some embodiments, the PGM component comprises palladium, platinum, or a mixture thereof. In some embodiments, the PGM component is a metal or an oxide thereof (e.g., platinum or an oxide thereof, but not limited thereto).

[0106] The PGM component may be present in an amount ranging from about 0.01 to about 20% based on the metal weight, based on the total weight of the DOC composition. The DOC composition may contain, for example, 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.% based on the weight of the dry DOC composition. In certain embodiments, the PGM of the DOC composition disclosed herein comprises both a platinum component and a palladium component. In some embodiments, the Pt / Pd ratio of the PGM component is about 10:1 to about 1:10. In some embodiments, the Pt / Pd weight ratio is about 2 / 1.

[0107] Typically, the platinum and palladium components of the disclosed DOC composition are both supported on a support material (wherein the support material on which the platinum and palladium components are supported may be the same or different). The support material may be zeolite or non-zeolite. A "non-zeolite support" or "non-zeolite support" in the catalyst layer refers to a material that is not a zeolite but accommodates a precious metal, stabilizer, promoter, binder, etc. through association, dispersion, impregnation, or other suitable methods. Examples of such non-zeolite supports include, but are not limited to, high surface area refractory metal oxides.

[0108] The support material upon which the catalytically active platinum component and the second palladium component are deposited comprises, for example, a refractory metal oxide that exhibits chemical and physical stability at high temperatures, such as those associated with gasoline or diesel engine exhaust gases. Exemplary refractory metal oxides include alumina, silica, zirconia, titania, ceria, praseodymia, tin oxide, etc., as well as physical mixtures or chemical combinations thereof that include atomically doped combinations and high surface area or highly active compounds such as active alumina. Combinations of metal oxides such as silica-alumina, ceria-zirconia, praseodymia-ceria, alumina-zirconia, alumina-ceria-zirconia, lantana-alumina, lantana-zirconia-alumina, baria-alumina, baria-lantana-alumina, baria-lantana-neodymia-alumina, and alumina-ceria are included. Exemplary aluminas include large-pore boehmite, gamma-alumina, and delta / theta alumina. Useful commercial aluminas used as starting materials in exemplary processes include high bulk density gamma-alumina, low or medium bulk density macropore gamma-alumina, and active aluminas such as low bulk density macropore boehmite and gamma-alumina.

[0109] High surface area metal oxide supports, such as alumina support materials also referred to as "gamma alumina" or "activated alumina," are typically 60 m 2 Exceeding / g, usually 200 m 2 It exhibits a BET surface area of ​​less than or greater than / g. An exemplary refractory metal oxide is approximately 50 m² 2 / g to about 300 m 2It comprises high surface area γ-alumina having a specific surface area of ​​1 / g. This activated alumina is generally a mixture of the gamma and delta phases of alumina, but may also contain significant amounts of eta, kappa, and theta alumina phases. "BET surface area" has a general meaning referring to the Brunauer, Emmett, Teller method, which determines the surface area by N2 adsorption. Preferably, the activated alumina is about 60 m² 2 / g to about 350 m 2 / g, for example, about 90 m 2 / g to about 250 m 2 It has a specific surface area of ​​ / g.

[0110] In certain embodiments, a metal oxide support useful for the DOC catalyst composition disclosed herein is a doped alumina material such as a Si-doped alumina material (including but not limited to 1-10% SiO2-Al2O3), a doped titania material such as a Si-doped titania material (including but not limited to 1-10% SiO2-TiO2), or a doped zirconia material such as Si-doped ZrO2 (including but not limited to 5-30% SiO2-ZrO2).

[0111] Accordingly, the refractory metal oxide or refractory mixed metal oxide in the DOC catalyst composition is typically selected from the group consisting of alumina, zirconia, silica, titania, ceria, e.g., bulk ceria, manganese oxide, zirconia-alumina, ceria-zirconia, ceria-alumina, lantana-alumina, baria-alumina, silica, silica-alumina, and combinations thereof.

[0112] The DOC catalyst composition may contain any amount of any of the aforementioned refractory metal oxides. For example, the refractory metal oxide in the catalyst composition may comprise about 15 wt%, about 20 wt%, about 25 wt%, about 30 wt%, or about 35 wt% to about 50 wt%, about 55 wt%, about 60 wt%, about 65 wt%, or about 70 wt% based on the total dry weight of the DOC catalyst composition. The DOC catalyst composition may comprise, for example, about 10 to about 99 wt% alumina, about 15 to about 95 wt% alumina, or about 20 to about 85 wt% alumina.

[0113] In some embodiments, the LT-NA composition as disclosed herein removes NO from an exhaust gas stream at a temperature of about 30°C to about 200°C, e.g., about 30°C, about 40°C, about 50°C, about 75°C, or about 100°C to about 125°C, about 150°C, about 175°C, or about 200°C. x Adsorbs components.

[0114] In some embodiments, the LT-NA composition is derived from the exhaust gas stream from NO present in the exhaust gas stream. x Based on the total amount of NO x At least 30 to 100% of the theoretical amount based on a 1:1 molar ratio of / Pd, for example, in an amount of about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, about 96%, about 97%, about 98%, about 99%, or about 100% of the theoretical amount of NO x Adsorbs components.

[0115] In some embodiments, the LT-NA composition disclosed herein is NO at a temperature of about 170°C to about 300°C, for example, about 170°C, about 180°C, 190°C, about 200°C, or about 225°C to about 250°C, about 275°C, or about 300°C. x It releases the components back into the exhaust gas stream.

[0116] In some embodiments, the LT-NA composition disclosed herein comprises NO adsorbed on the LT-NA composition x NO in an amount of at least 55 to about 100 wt% based on the total amount of the component, for example, about 55 wt%, about 60 wt%, about 65 wt%, about 70 wt%, about 75 wt%, about 80 wt%, about 85 wt%, about 90 wt%, about 95 wt%, or about 100 wt%. x It releases the components back into the exhaust gas stream.

[0117] In some embodiments, the catalyst composition is novel. In other embodiments, the catalyst composition has been aged. "Aging" means that the composition or an article containing such composition has been exposed to an elevated temperature for an extended period of time, simulating the conditions under which the composition is exposed while used in a vehicle exhaust treatment system. Such aging may be referred to as "thermal aging."

[0118] In some embodiments, the LT-NA composition disclosed herein is a first NO x Having an adsorption capacity value, and after hydrothermal aging at 750℃ for a period of 2 to 80 hours, the second NO x It has an adsorption capacity value; where the second NO x The adsorption capacity value is the first NO x It is equal to or greater than the adsorption capacity value. A comparison of the first and second adsorption capacities provides an indication of stability under vehicle application conditions. In some embodiments, the LT-NA composition disclosed herein has improved NO after such hydrothermal aging. xIt has an adsorption capacity (i.e., the second adsorption capacity is greater than the first adsorption capacity). Surprisingly, in some embodiments, the second NO of the LT-NA composition disclosed herein x It was found that the adsorption capacity is improved compared to an LT-NA composition containing a zeolite that includes a first metal component and does not include a second metal component. Although I do not wish to be bound by any theory or principle, the presence of the second metal component is believed to play a role in stabilizing and promoting the activity of the zeolite containing the first metal component.

[0119] Preparation of catalyst composition

[0120] In some embodiments, the disclosed LT-NA catalyst and DOC compositions may be prepared via an initial wet impregnation method. The initial wet impregnation technique, also known as capillary impregnation or dry impregnation, is generally used for the synthesis of heterogeneous materials, namely catalysts. Typically, a metal precursor is dissolved in an aqueous or organic solution, and the metal-containing solution is then added to a catalyst support (e.g., zeolite or refractory metal oxide) containing a pore volume equal to the volume of the added solution. Capillary action draws the solution into the pores of the support. The solution added in excess of the support pore volume causes the solution transport to shift from a capillary action process to a much slower diffusion process. The catalyst is then dried and calcined to remove volatile components in the solution, thereby depositing the metal onto the surface of the catalyst support. The maximum loading is limited by the solubility of the precursor in the solution. The concentration profile of the impregnated material depends on the mass transfer conditions within the pores during impregnation and drying. Those skilled in the art will be aware of other methods of loading metal components into the support of the composition, such as adsorption, ion-exchange, precipitation, etc.

[0121] For example, palladium can be impregnated onto the zeolite during the preparation of the components of the LT-NA catalyst composition. Palladium salts useful for introducing palladium components into the zeolite include, but are not limited to, nitrates.

[0122] In some embodiments, the first metal component, the second metal component, or both are ion-exchanged in the zeolite. Ion exchange is a process commonly used to exchange ions in a porous support with external metal ions of interest. The zeolite framework contains open pores in the form of channels and cages, which are typically occupied by water molecules that can be replaced and extra-framework cations. Aluminum atoms attract the excess negative charge compensated by these cations. The interior of the pore system is marked as the catalytically active surface. The more aluminum and silicon the zeolite contains, the denser the negative charge of the lattice becomes, and the more polar the interior surface is.

[0123] Because divalent or trivalent cations exist as tetrahedral centers in the zeolite framework, the zeolite accommodates a negative charge in the form of so-called anionic sites located near the corresponding cation positions. This negative charge is compensated by incorporating cations, such as metal cations, into the pores of the zeolite material. The cations that balance the charge of the anionic framework are loosely associated with the framework oxygen, and the remaining pore volume is filled with water molecules. Non-framework cations are generally exchangeable, and water molecules can be removed. These pores and channels are characteristic of each zeolite. The term "exchange site" refers to a site available for cations that is primarily occupied by ion-exchanged metal cations intentionally added to the zeolite (e.g., palladium).

[0124] For example, sodium or NH4 present in the pores +Zeolites prepared with ions can be exchanged, for example, with palladium ions to form palladium ion-exchanged zeolites. This is achieved by preparing a slurry of zeolite in a solution containing palladium ions. Heat may be optionally applied during this process. The palladium ions then diffuse into the pores of the zeolite, and the residual ions, namely Na₂ + or NH4 + A palladium ion-exchanged zeolite can be formed by exchanging with. "Palladium ion-exchanged" means that at least a portion of the ion exchange sites is occupied by palladium ions. In particular, it is desirable that more than 50%, preferably more than 70%, of the exchangeable sites be exchanged with palladium.

[0125] Similarly, for the preparation of the DOC composition disclosed herein, a support material (e.g., zeolite or refractory metal oxide) is impregnated using an aqueous solution of a soluble compound or complex of a platinum group metal (PGM). Non-limiting examples of suitable compounds include palladium nitrate, tetraammine palladium nitrate, tetraammine platinum acetate, and platinum nitrate. During the calcination step, or at least during the initial stage of using the complex, these compounds are converted into the catalytically active form of the metal or its compound. A suitable method for preparing the DOC catalyst composition is to prepare a mixture of a solution of the desired PGM compound (e.g., a platinum compound and / or a palladium compound) and at least one support, such as a finely divided high-surface-area refractory metal oxide support, e.g., gamma alumina, which is sufficiently dry to absorb substantially all of the solution and subsequently combine with water to form a wet solid that forms a coatable slurry. In one or more embodiments, the slurry is acidic, for example, having a pH of about 2 or more and less than about 7. The pH of the slurry can be lowered by adding an appropriate amount of inorganic or organic acid to the slurry. A combination of both may be used, considering the compatibility between the acid and the raw material. Inorganic acids include, but are not limited to, nitric acid. Organic acids include, but are not limited to, acetic acid, propionic acid, oxalic acid, malonic acid, succinic acid, glutamic acid, adipic acid, maleic acid, fumaric acid, phthalic acid, tartaric acid, citric acid, etc.

[0126] Catalyst articles

[0127] In one or more embodiments, the LT-NA composition is disposed (coated) on a substrate to form a catalytic article (i.e., a catalytic component or a catalytic article). Such an article is part of an exhaust gas treatment system (e.g., a catalytic article including, but not limited to, an article containing the LT-NA composition disclosed herein). As used herein, the terms “catalytic article,” “catalytic article,” “catalytic component,” “catalytic component,” “article,” and “component” are used interchangeably regardless of any specific catalytic activity. For example, an LT-NA article may be referred to as a catalytic article, but such an article is recognized as having adsorption properties rather than catalytic functions, although no specific theory of operation is desired to be bound by it. Similarly, “composition” and “catalytic composition” are used interchangeably herein regardless of any specific catalytic activity.

[0128] In one aspect of the present disclosure, a catalytic article for treating an exhaust stream of an internal combustion engine is provided, the catalytic article comprises a substrate having an inlet end and an outlet end defining the entire length; and a first washcoat comprising an LT-NA composition as disclosed herein disposed on at least a portion thereof. In some embodiments, the catalytic article disclosed herein further comprises a second washcoat comprising a diesel oxidation catalyst (DOC) composition disposed on at least a portion of the substrate in a layered or zoned configuration.

[0129] To manufacture a catalytic article, a substrate is coated with a catalytic composition disclosed herein (i.e., LT-NA and / or DOC composition). The coating is a “catalytic coating composition” or a “catalytic coating.” The terms “catalytic composition” and “catalytic coating composition” are synonyms.

[0130] Coating composition

[0131] Coating compositions comprising the LT-NA and / or DOC compositions disclosed herein may be prepared using a binder, such as a ZrO2 binder derived from a suitable precursor like zirconyl acetate or any other suitable zirconium precursor like zirconyl nitrate. Zirconyl acetate binders provide a coating that remains homogeneous, undamaged, and intact even after thermal aging, for example, when the catalyst is exposed to a high temperature of at least about 600°C, e.g., about 800°C, and a high-temperature steam environment of about 5% or more. Other potentially suitable binders include, but are not limited to, alumina and silica. Alumina binders include aluminum oxide, aluminum hydroxide, and aluminum oxyhydroxide. Aluminum salts and colloidal forms of alumina are also widely used. Silica binders include various forms of SiO2, including silicates and colloidal silica. The binder composition may include any combination of zirconia, alumina, and silica. Other exemplary binders include boehmite, gamma-alumina, or delta / theta alumina, and silica sol. If present, the binder is typically used in an amount of about 1 to 5 weight percent of the total washcoat loading. Alternatively, the binder may be zirconia-based or silica-based, for example, zirconium acetate, zirconia sol, or silica sol. If present, the alumina binder is typically about 0.05 g / in 3 Up to about 1 g / in 3 It is used in the amount of

[0132] write

[0133] A useful material is a three-dimensional one having length, diameter, and volume similar to a cylinder. The shape does not necessarily have to correspond to a cylinder. The length is the axial length defined by the inlet end and the outlet end.

[0134] According to one or more embodiments, the substrate for the disclosed composition(s) may be composed of any material typically used in manufacturing automotive catalysts and will typically include a metal or ceramic honeycomb structure. The substrate typically provides a plurality of wall surfaces upon which a washcoat composition is applied and adhered, thereby acting as a substrate for the catalyst composition.

[0135] 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-magnesia, zircon silicate, silimanite, magnesium silicate, zircon, petalite, α-alumina, aluminosilicate, etc.

[0136] The substrate may also be a metal comprising one or more metals or metal alloys. The metal substrate may comprise any metal substrate, such as having openings or "punch-outs" in the channel walls. The metal substrate may be used in various shapes, such as pellets, corrugated sheets, or monolithic foams. Specific examples of the metal substrate include heat-resistant non-metallic alloys, in particular those in which iron is a substantial or major component. Such alloys may contain one or more of nickel, chromium, and aluminum, and these metals together may advantageously comprise at least about 15 wt% of the alloy, for example, about 10 to about 25 wt% chromium, about 1 to about 8 wt% aluminum, and 0 to about 20 wt% nickel, based on the weight of the substrate in each case. Examples of the metal substrate include a substrate having straight channels; a substrate having blades protruding along axial channels to obstruct gas flow and open communication of gas flow between channels; It includes a substrate having holes that enable radial gas transport throughout the monolith by improving gas transport between the blades and also between the channels. A metal substrate is advantageously used in certain embodiments that allow rapid heating of the substrate and, correspondingly, rapid heating of the catalyst composition (e.g., LT-CO oxidation catalyst composition) coated therein, particularly at closely coupled locations.

[0137] Any substrate suitable for the catalytic articles disclosed herein may be used, such as a monolithic substrate of the type having fine, parallel gas flow passages extending from an inlet or outlet face of the substrate so as to be open to fluid flow through it ("through-type substrate"). Other suitable substrates are of the type having a plurality of fine, substantially parallel gas flow passages extending along the longitudinal axis of the substrate, typically each passage being blocked at one end of the substrate body and alternating passages being blocked at opposite end faces ("wall-flow type filter"). Through-type and wall-flow type substrates are also taught, for example, in International Application Publication WO2016 / 070090, the entire text of which is incorporated herein by reference.

[0138] In some embodiments, the catalyst substrate comprises a honeycomb substrate in the form of a wall-flow filter or a perforated substrate. In some embodiments, the substrate is a wall-flow filter. Perforated substrates and wall-flow filters will be discussed further below.

[0139] perfusion type device

[0140] In some embodiments, the substrate is a perforated substrate (e.g., a monolithic substrate including a perforated honeycomb monolithic substrate). The perforated substrate has fine, parallel gas flow passages extending from the inlet end to the outlet end of the substrate so that the passages are open to fluid flow. The passages, which are essentially straight paths from the fluid inlet to the fluid outlet, are defined by walls on which a catalyst coating is placed so that the gas flowing through the passages comes into contact with the catalyst material. The flow passages of the perforated substrate are thin-walled channels, which may have any suitable cross-sectional shape and size, such as trapezoidal, rectangular, square, sinusoidal, hexagonal, elliptical, circular, etc. As previously described, the perforated substrate may be ceramic or metal.

[0141] A perfusion-type substrate is, for example, about 50 in 3 to about 1200 in 3 It may have a volume of about 60 cells per square inch (cpsi) to about 500 cpsi or about 900 cpsi or less, for example, a cell density (inlet opening) of about 200 to about 400 cpsi, and a wall thickness of about 50 to about 200 microns or about 400 microns.

[0142] FIGS. 1a and 1b illustrate an exemplary substrate (2) in the form of a perforated substrate coated with the LT-NA composition described herein. Referring to FIG. 1a, 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) identical to the end face (6). The substrate (2) has a plurality of fine, parallel gas flow passages (10) formed therein. As shown in FIG. 1b, the flow passages (10) are formed by walls (12) and extend through the carrier (2) from the upstream end face (6) to the downstream end face (8), and the passages (10) are not obstructed so that the flow of a fluid, for example, a gas stream, can penetrate the carrier (2) longitudinally through its gas flow passages (10). As can be more easily seen in FIG. 1b, the wall (12) is dimensioned and configured so that the gas flow passage (10) has a substantially regular polygonal shape. As illustrated, the LT-NA composition may be applied to a number of distinct layers if desired. In the illustrated embodiment, the LT-NA composition consists of both a distinct lower layer (14) attached to the wall (12) of the carrier member and a second distinct upper layer (16) coated on the lower layer (14). The invention may be implemented with one or more layers of LT-NA composition (e.g., two, three, or four or more) and is not limited to the two-layer embodiment illustrated in FIG. 1b. Additional coating configurations are disclosed below.

[0143] Wall-flow type filter material

[0144] In some embodiments, the substrate is a wall-flow filter having a plurality of fine, substantially parallel gas flow passages that generally extend along the longitudinal axis of the substrate. Typically, each passage is blocked at one end of the substrate body, and alternate passages are blocked at opposite end faces. Such monolithic wall-flow filter substrates may contain about 900 or fewer flow passages (or "cells") per square inch of cross-section, but may be used with much fewer. For example, the substrate may have about 7 to 600, more generally about 100 to 400 cells / square inch ("cpsi"). Cells may have cross-sections of rectangular, square, circular, elliptical, triangular, hexagonal, or other polygonal shapes.

[0145] FIG. 2 is a perspective view of an exemplary wall-flow filter. A cross-sectional view of a section of a monolithic wall-flow filter substrate is illustrated in FIG. 2, showing alternating blocked and open passages (cells). Blocked or blocked ends (100) alternate with open passages (101), and each opposing end is open and blocked, respectively. The filter has an inlet end (102) and an outlet end (103). An arrow across the porous cell wall (104) indicates exhaust gas flow entering the open cell end, diffusing through the porous cell wall (104), and exiting through the open outlet cell end. The blocked end (100) prevents gas flow and facilitates diffusion through the cell wall. Each cell wall will have an inlet side (104a) and an outlet side (104b). The passages are surrounded by cell walls.

[0146] The wall-flow type filter article material is, for example, about 50 cm 3 , about 100 cm 3 , about 200 cm 3 , about 300 cm 3, approximately 400 cm 3 , about 500 cm 3 , approximately 600 cm 3 , approximately 700 cm 3 , approximately 800 cm 3 , approximately 900 cm 3 or about 1000 cm 3 to about 1500 cm 3 , approximately 2000 cm 3 , approximately 2500 cm 3 , approximately 3000 cm 3 , approximately 3500 cm 3 , approximately 4000 cm 3 , approximately 4500 cm 3 or about 5000 cm 3 It may have a volume. The wall-flow filter substrate typically has a wall thickness of about 50 microns to about 2000 microns, for example, about 50 microns to about 450 microns or about 150 microns to about 400 microns.

[0147] The walls of the wall-flow filter are porous and generally have a wall porosity of at least about 50% or at least about 60% and an average pore size of at least about 5 microns prior to the application of a functional coating. For example, the wall-flow filter article substrate will have a porosity of ≥ 50%, ≥ 60%, ≥ 65%, or ≥ 70% in some embodiments. For example, 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 microns, about 10 microns, about 20 microns, about 30 microns, about 40 microns, or about 50 microns to about 60 microns, about 70 microns, about 80 microns, about 90 microns, or about 100 microns prior to the placement of the catalyst coating. The terms "wall porosity" and "substrate porosity" mean the same thing and are interchangeable. Porosity is the ratio of the pore volume of the substrate to the total volume. The pore size can be determined according to the ISO 15901-2 (static volume) procedure for nitrogen pore size analysis. Nitrogen pore size can be measured using a Micromeritics TRISTAR 3000 series instrument. Nitrogen pore size can be determined using BJH (Barrett-Joyner-Halenda) calculations and 33 desorption points. A useful wall-flow filter has a high porosity, allowing for high loading of the catalyst composition without excessive back pressure during operation.

[0148] coating

[0149] An article is formed by coating a substrate with the LT-NA and / or DOC composition disclosed herein. The coating may comprise one or more thin adhesive coating layers disposed on and attached to at least a portion of the substrate. In some embodiments, the article may comprise the use of one or more layers and a combination of one or more layers. The coating composition may be present on the inlet side alone, the outlet side alone, or both the inlet and outlet sides of the substrate wall, or the wall itself may consist of all or part of the catalytic composition. The coating may be on the surface of the substrate wall and / or within the pores of the substrate wall, i.e., "inside" and / or "on" the substrate wall. Thus, the phrase "catalytic coating disposed on the substrate" means on any surface, e.g., on the wall surface and / or on the pore surface. The coating layer(s) may comprise individual functional components, namely the LT-NA composition and / or the DOC catalytic composition as described herein, respectively.

[0150] The catalyst composition may typically be applied in the form of a washcoat containing a support material having a catalytically active species thereon. In some embodiments, the catalyst components may also be combined into a single washcoat. The washcoat is formed by preparing a slurry containing a support with a specified solid content (e.g., 10 wt% to 60 wt%) in a liquid vehicle, then applying this onto a substrate, drying, and calcining to provide a coating layer. When multiple coating layers are applied, the substrate is dried and calcined after each layer is applied and / or after a number of desired multiple layers are applied. In one or more embodiments, the catalyst material(s) are applied to the substrate as a washcoat. A binder may also be used as described above.

[0151] The catalyst composition(s) mentioned above are generally mixed independently of water to form a slurry for the purpose of coating a catalyst substrate, such as a honeycomb substrate. In addition to catalyst particles, the slurry may optionally contain a binder (e.g., alumina, silica), a water-soluble or water-dispersible stabilizer, an accelerator, an associative thickener, and / or a surfactant (including anionic, cationic, nonionic, or amphoteric surfactants). A typical pH range for the slurry is about 3 to about 6. Thus, the pH can be adjusted by adding acidic or basic species to the slurry. For example, in some embodiments, the pH of the slurry is adjusted by adding ammonium hydroxide or aqueous nitric acid.

[0152] The slurry may be milled to improve particle mixing and the formation of a homogeneous material. Milling may be performed in a ball mill, a continuous mill, or other similar equipment, and the solid content of the slurry may be, for example, about 20 wt% to 60 wt%, more specifically about 20 wt% to 40 wt%. In one embodiment, after milling, the slurry is characterized by a D90 particle size of about 10 to about 40 microns, preferably 10 to about 30 microns, more preferably about 10 to about 15 microns.

[0153] Next, the slurry is coated onto a catalyst substrate using any washcoat technique known in the art. In one embodiment, the catalyst substrate is immersed in the slurry one or more times or otherwise coated with the slurry. The coated substrate is then dried at a high temperature (e.g., 100 to 150°C) for a certain period (e.g., 10 minutes to 3 hours), and then calcined by heating, for example, at 400 to 600°C for typically about 10 minutes to about 3 hours. After drying and calcination, the final washcoat coating layer can be considered to be essentially solvent-free.

[0154] After calcination, the catalyst loading obtained by the aforementioned washcoat technique can be determined by calculating the difference between the coated weight and the uncoated weight of the substrate. As is obvious to those skilled in the art, the catalyst loading can be adjusted by changing the slurry rheology. Additionally, the coating / drying / calcination process for producing the washcoat can be repeated as needed to build the coating to a desired loading level or thickness, which means that more than one washcoat may be applied.

[0155] Washcoat(s) may be applied such that different coating layers can come into direct contact with the substrate. Alternatively, one or more "undercoats" may be present so that the catalyst or adsorbent coating layer or at least a portion of the coating layers may not come into direct contact with the substrate (rather, come into contact with the undercoat). One or more "overcoats" may also be present so that the coating layer or at least a portion of the coating layers may not be directly exposed to the gas stream or atmosphere (rather, come into contact with the overcoat).

[0156] Different coating layers may be in direct contact with each other without an "intermediate" overlapping zone. Alternatively, different coating layers may not be in direct contact with a "gap" between the two zones. In the case of an "undercoat" or "overcoat," the gap between the different layers is called an "intermediate layer." The undercoat is the layer "below" the coating layer, the overcoat is the layer "above" the coating layer, and the intermediate layer is the layer "between" the two coating layers. The intermediate layer(s), undercoat(s), and overcoat(s) may contain one or more functional compositions or may not contain functional compositions.

[0157] The catalyst coating may comprise one or more thin adhesive layers, the layers being bonded to each other and the coating being bonded to the substrate. The entire coating comprises individual "coating layers." The catalyst coating may advantageously be "zoned" and may comprise a zoned catalyst layer. This may also be described as "transversely zoned." For example, a layer may extend from the inlet end toward the outlet end by about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, or about 90% of the substrate length. Another layer may extend from the outlet end toward the inlet end by about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, or about 90% of the substrate length. Different coating layers may be adjacent to each other and may not overlap each other. Alternatively, different layers may overlap parts of each other to provide a third "intermediate" zone. The intermediate zone may be extended, for example, by about 5% to about 80% of the substrate length, for example by about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, or about 70% of the substrate length.

[0158] The different layers may each extend the entire length of the substrate or extend a portion of the length of the substrate, and may be placed partially or wholly on top of or below each other. Each of the different layers may extend from an inlet end or an outlet end.

[0159] Different catalyst compositions may be present in separate coating layers. For example, one coating layer may comprise the LT-NA composition disclosed herein, and another coating layer may comprise the DOC composition disclosed herein. Alternatively, in some embodiments, the LT-NA composition and the DOC composition as each disclosed herein may be combined and applied to the substrate as a single homogeneous layer. In further embodiments, the LT-NA composition may be present in one layer, and the DOC composition components may be divided among one or more additional layers.

[0160] Therefore, discussions regarding different layers may apply to any of these layers. The catalyst coating may comprise one, two, or three or more coating layers. One or more coating layers together comprise a catalyst composition.

[0161] The zones of the present disclosure are defined by the relationship of the coating layers. With respect to different coating layers, there are a number of possible zone configurations. For example, there may be an upstream zone and a downstream zone, or there may be an upstream zone, an intermediate zone, and a downstream zone, or there may be four different zones, etc. If two layers are adjacent and do not overlap, there are upstream and downstream zones. If two layers overlap to some extent, there are upstream, downstream, and intermediate zones. For example, if the coating layer extends the entire length of the substrate and different coating layers extend a specific length from the exit end and overlap with a portion of the first coating layer, there are upstream and downstream zones. The catalyst coating may comprise more than one identical layer.

[0162] In some embodiments, the first washcoat is disposed directly on the substrate, and the second washcoat is disposed on at least a portion of the first washcoat. In some embodiments, the second washcoat is disposed directly on the substrate, and the first washcoat is disposed on at least a portion of the second washcoat. In some embodiments, the first and second washcoat compositions are combined and disposed on the substrate as a single homogeneous layer. In some embodiments, the catalyst article has a zoned configuration, wherein the first washcoat is disposed on the catalyst substrate from the inlet end for a length of about 10% to about 70% of the total length; and the second washcoat is disposed on the catalyst substrate from the outlet end for a length of about 30% to about 90% of the total length.

[0163] FIGS. 3A, 3B, and 3C illustrate some possible coating layer configurations having two coating layers. A monolithic wall-flow filter substrate wall (200) on which coating layers (201, 202) are disposed is illustrated. This is a simplified example, and in the case of a porous wall-flow substrate, pores and coatings attached to the pore walls are not illustrated, and blocked ends are not illustrated. In FIG. 3A, the coating layer (201) extends about 50% of the substrate length from the inlet to the outlet; the coating layer (202) extends about 50% of the substrate length from the inlet to the outlet, and the coating layers are adjacent to each other to provide an inlet upstream zone (203) and an outlet downstream zone (204). In FIG. 3B, the coating layer (202) extends about 50% of the substrate length from the outlet; Layer (201) extends more than 50% of the length from the inlet and overlaps a portion of layer (202) to provide an upstream zone (203), an intermediate zone (205), and a downstream zone (204). In FIG. 3c, the coating layers (201, 202) each extend the entire length of the substrate, and layer (201) overlaps with layer (202). The substrate of FIG. 3c does not include a zoned coating composition. FIG. 3a, FIG. 3b, and FIG. 3c may be useful for illustrating a coating composition on a wall-through type substrate. FIG. 3a, FIG. 3b, and FIG. 3c may also be useful for illustrating a coating composition on a permeable type substrate as described below. The composition of such coating layers is not limited.

[0164] In some embodiments, the DOC composition is a zoned configuration with respect to the LT-NA composition layer(s). In some embodiments, the DOC composition may overlap with one or more layers of the LT-NA composition. In some embodiments, the LT-NA catalyst composition and the DOC composition exist on the substrate as a single homogeneous layer. In some embodiments, the LT-NA catalyst composition and the DOC composition exist in separate individual layers. In some embodiments, the LT-NA catalyst composition and the DOC composition exist as a zoned configuration. In some embodiments, another catalyst composition may be included on, under, or between any of the LT-NA and DOC catalyst composition layers referenced herein.

[0165] The loading of the catalyst coating (e.g., LT-NA and / or DOC) on the substrate will depend on substrate characteristics such as porosity and wall thickness. Typically, the catalyst loading on a wall-flow filter will be lower than the catalyst loading on a perforated substrate. Catalytic wall-flow filters are disclosed, for example, in U.S. Patent No. 7,229,597, the entirety of which is incorporated herein by reference. The LT-NA and / or DOC catalyst composition is generally, for example, about 0.3 to 5.5 g / in based on the substrate 3 , or about 0.4 g / in 3 , approximately 0.5 g / in 3 , approximately 0.6 g / in 3 , approximately 0.7 g / in 3 , approximately 0.8 g / in 3 , approximately 0.9 g / in 3 or about 1.0 g / in 3 Up to about 1.5 g / in 3 , approximately 2.0 g / in 3 , approximately 2.5 g / in 3 , approximately 3.0 g / in 3 , approximately 3.5 g / in 3 , approximately 4.0 g / in 3 , Approximately 4.5 g / in 3 , Approx. 5.0 g / in 3 or about 5.5 g / in 3 It is present on the substrate at a concentration. The concentration of the catalyst composition or any other component on the substrate refers to the concentration per any one three-dimensional section or zone, for example, the substrate or the entire substrate.

[0166] In some embodiments, the catalyst article contains about 15 g / ft of the first metal component. 3 Up to about 200 g / ft 3 or about 60 g / ft 3 Up to about 120 g / ft 3 Includes as a loading of. In some embodiments, the LT-NA article is about 1 g / in 3 Up to about 5 g / in 3 or about 2 g / in 3 Up to about 3 g / in 3 It includes a total zeolite loading. In some embodiments, the catalyst article includes a silica-to-alumina ratio (SAR) of about 5 to about 50 or about 10 to about 35.

[0167] In some embodiments, the catalytic article disclosed herein exhibits enhanced oxidation of carbon monoxide (CO), hydrocarbons (HC), or both after the catalytic article is hydrothermally aged at 750°C for a period of 80 hours, compared to oxidation of carbon monoxide (CO), hydrocarbons (HC), or both prior to hydrothermal aging.

[0168] In some embodiments, enhanced oxidation of CO or HC is measured in terms of conversion efficiency. In some embodiments, the conversion efficiency is measured at the light-off temperature (i.e., T 50It is measured as a function of ). The light-off temperature is the temperature at which the catalyst composition can convert 50% of the hydrocarbons into carbon dioxide and water. Typically, the lower the measured light-off temperature for any given catalyst composition, the more efficient the catalyst composition is at performing the catalytic reaction, e.g., hydrocarbon conversion. In some embodiments, the conversion efficiency is measured as a function of the percentage of conversion to CO2 at a specific temperature or over a temperature range.

[0169] Exhaust gas treatment system

[0170] The present disclosure concerns NO in the exhaust gas stream from an internal combustion engine. x An exhaust gas treatment system for reducing the level is further provided, said exhaust gas treatment system comprises the catalytic article disclosed herein. In another aspect of the invention, NO in an exhaust gas stream from an internal combustion engine x A method for reducing the level is provided, comprising bringing an exhaust gas stream into contact with the catalytic article disclosed herein or the exhaust treatment system disclosed herein. Accordingly, the present invention provides an exhaust treatment system comprising the catalytic article described herein, for example, an engine that generally generates an exhaust gas stream and one or more catalytic articles located downstream of the engine that are in fluid communication with the exhaust gas stream. The engine may be, for example, a diesel engine operating under combustion conditions that use an excess amount of air compared to that required for stoichiometric combustion, i.e., lean conditions. In other embodiments, the engine may be an engine associated with a stationary source (e.g., a generator or a pumping station). In some embodiments, the exhaust treatment system further comprises one or more additional catalytic components. The relative arrangement of the various catalytic components present within the exhaust treatment system may vary.

[0171] In the exhaust gas treatment system and method of the present invention, the exhaust gas stream is received within the article(s) or treatment system by entering at an upstream end and exiting at a downstream end. The inlet end of the material or article is synonymous with the "upstream" end or "forward" end. The outlet end is synonymous with the "downstream" end or "rear" end. The treatment system is generally located downstream of the internal combustion engine and is in fluid communication with it.

[0172] The system disclosed herein includes an LT-NA article that may include a perforating or wall-flow filter substrate as disclosed herein. In particular, the system NO at low temperatures x NO that adsorbs and is trapped at high temperatures x It includes an LT-NA catalyst article suitable for emitting NO of the catalyst composition. x The adsorption component is desirable NO under various engine operating conditions x It provides adsorption and desorption characteristics.

[0173] Preferably, the LT-NA catalyst article is a substantial portion of No present in the exhaust gas stream. x It can adsorb. However, more importantly, the LT-NA catalyst article can adsorb No until the exhaust gas stream and / or exhaust gas emission system reaches a temperature high enough for other catalyst components to be activated. x It does not release the species. Only then is the released No x It can be efficiently converted into N2 and exit the exhaust gas treatment system. As such, LT-NA catalyst articles generally reduce the NO emitted from LT-NA x It is located upstream of any catalytic component dedicated to the conversion of. In some embodiments, the LT-NA catalytic article is positioned upstream of any catalytic component dedicated to the conversion of NO present in the exhaust gas stream at low temperatures, which can be optionally treated with at least a DOC and / or CSF component. x It adsorbs species.

[0174] In some embodiments, the LT-NA catalyst article may not be located within separate components (e.g., on separate substrates) but may be included within the same component, such as a diesel oxidation catalyst (DOC), a catalyzed soot filter (CSF), or a catalytic selective reduction (SCR) catalyst component, wherein the catalyst composition for these components is applied to the substrate in a zoned or layered configuration. In some embodiments, the LT-NA and (DOC) are combined in a single catalyst article.

[0175] The system of the present disclosure, in addition to the LT-NA catalyst article, comprises, for example, a DOC, a reducing agent injector, an SCR catalyst component, a soot filter (which may be catalyzed or non-catalyzed) and / or an ammonia oxidation catalyst (AMO). x It may contain ). A DOC suitable for use in an exhaust treatment system can effectively catalyze the oxidation of CO and HC to carbon dioxide (CO2). Preferably, the DOC can convert at least 50% of the CO or HC components present in the exhaust gas. The DOC may be located downstream of, for example, an LT-NA catalyst article. In some embodiments, the DOC is located upstream of an SCR catalyst component and / or a soot filter.

[0176] The exhaust gas treatment system of the present disclosure may further include an SCR catalyst component. The SCR catalyst component may be located upstream or downstream of the DOC and / or soot filter. An SCR catalyst component suitable for use in an exhaust treatment system is NO at temperatures as high as 650°C x It can effectively catalyze the reduction of exhaust components. In addition, SCR catalyst components can reduce NO even under low-load conditions, which are typically associated with lower exhaust temperatures. x It must be active for the reduction of NO. Preferably, the SCR catalyst component depends on the amount of reducing agent added to the system. xIt is possible to convert more than 50% of the (e.g., NO) components into N2. Another desirable property of the SCR catalyst component is that it has the ability to catalyze the reaction of O2 with any excess NH3 to form N2 so that NH3 is not released into the atmosphere. Useful SCR catalyst components used in emission treatment systems must also have heat resistance to temperatures exceeding 650°C. Such high temperatures may be encountered during the regeneration of catalyzed soot filters. Suitable SCR catalyst components are described, for example, in U.S. Patents No. 4,961,917 and No. 5,516,497, the full text of each of which is incorporated herein by reference.

[0177] In some embodiments, the exhaust gas treatment system is lean NO x Lean Trap (LNT), Selective Catalytic Reduction (SCR) catalyst, ammonia or ammonia precursor injection component, Catalytic Soot Filter (CSF), or Ammonia Oxidation (AMO x It additionally includes one or more of the catalysts.

[0178] A specific illustrated exhaust gas treatment system may be more easily understood by referring to FIG. 4, which illustrates a schematic diagram of a non-limiting exhaust gas treatment system (20) according to an embodiment of the present disclosure. Those skilled in the art will recognize that it may be desirable to arrange the relative positions of each article in a different order than illustrated herein, and that such an alternative order is taken into account by the present disclosure. As illustrated, the exhaust treatment system (20) may include a plurality of catalytic components in succession downstream of an engine (22), such as a diesel engine. At least one of the catalytic components will be the LT-NA catalyst of the present invention as described herein. The catalytic composition of the present invention may be combined with a plurality of additional catalytic materials and may be placed in various positions relative to the additional catalytic materials. FIG. 4 illustrates five catalytic components ( 24, 26, 28, 30, 32...is illustrated in succession; however, the total number of catalyst components may vary, and five components are merely one example. Those skilled in the art will recognize that it may be desirable to arrange the relative positions of each article in a different order than that illustrated herein, and that such an alternative order is taken into account by the present disclosure.

[0179] Table 1 presents, without limitation, various exhaust gas treatment system configurations of one or more embodiments. Each catalyst is connected to the next catalyst through an exhaust conduit, so that the engine is upstream of catalyst A, which is upstream of catalyst B, which is upstream of catalyst C, which is upstream of catalyst D, and which is upstream of catalyst E (if present). References to components A through E in the table may be cross-referenced by the same names in FIG. 4.

[0180] In the table, references to SCR indicate SCR catalysts; any suitable SCR catalyst known in the art may be used.

[0181] AMO in the table x Reference to [the term] refers to an ammonia oxidation catalyst, which may be provided downstream of a catalyst of one or more embodiments of the present invention to remove any escaped ammonia from an exhaust gas treatment system. In certain embodiments, AMO x The catalyst may include a PGM component. In one or more embodiments, AMO x The catalyst may include a bottom coat having PGM and an top coat having SCR functionality.

[0182] As recognized by those skilled in the art, in the configurations listed in Table 1, any one or more of components A, B, C, D, or E may be placed in a particulate filter, such as a wall-flow filter, or placed on a perforating honeycomb substrate. In one or more embodiments, the engine exhaust system includes one or more catalytic components mounted at a location near the engine (closely coupled location, CC), and additional catalytic components are located at the lower part of the vehicle body (under-floor location, UF). In one or more embodiments, the exhaust gas treatment system may additionally include a urea injection component.

[0183]

[0184] Any exemplary exhaust gas treatment system illustrated in FIG. 4 uses a selective ammonia oxidation catalyst (AMO) to remove NH3 emitted from SCR catalyst components and selectively oxidize it to N2. x ) may follow.

[0185] Method for treating exhaust gas streams

[0186] An aspect of the present disclosure relates to a method for treating a lean-burning engine exhaust gas stream, the method comprising bringing the exhaust gas stream into contact with the catalytic article of the present disclosure or the exhaust treatment system of the present disclosure.

[0187] In some embodiments, the method comprises the step of continuously passing an exhaust gas stream in contact with an LT-NA catalyst article—said that the exhaust gas stream is at an initial temperature of about 150°C or lower and is gradually heated during additional engine operation—; and removing NO from the exhaust gas stream until the exhaust gas stream reaches a predetermined temperature. x Step of adsorbing and storing - where NO xis released into the exhaust gas stream exiting the LT-NA article -; and as the temperature of the exhaust gas stream increases and these downstream catalytic materials are heated to an operating temperature of about 200°C to about 450°C, respectively, No x The method includes the step of continuously passing an exhaust gas stream exiting the LT-NA component to come into contact with at least one downstream catalytic material for the removal of components.

[0188] LT-NA's NO x Method for controlling adsorption / desorption profiles

[0189] In another embodiment, NO of the LT-NA composition x Adsorption / Desorption Profiles and NO of LT-NA Composition x A method for controlling one or both of a desorption temperature range is provided, wherein the LT-NA composition comprises a zeolite comprising a first metal component and a second metal component, wherein the first metal component comprises palladium, and the second metal component is selected from the group consisting of an alkaline earth metal component, an oxide of an alkaline earth metal component, a rare earth metal component, an oxide of a rare earth metal component, and combinations thereof, and the method comprises selecting the second metal component and its loading. In some embodiments, NO x The desorption temperature range is about 150, about 175, about 200, about 225, or about 250 to about 275, about 300, about 325, about 350, or about 400°C.

[0190] The present article, system, and method are suitable for treating exhaust gas streams from moving emission sources such as trucks and automobiles. The present article, system, and method are also suitable for treating exhaust streams from stationary sources such as power plants.

[0191] It will be apparent to those skilled in the art that appropriate modifications and adaptations to the compositions, methods, and uses described herein may be made without departing from the scope of any of their embodiments or modes. The compositions and methods provided are exemplary and are not intended to limit the scope of the claimed embodiments. All of the various embodiments, modes, and options disclosed herein may be combined in any variation. The scope of compositions, formulations, methods, and processes described herein includes all actual or potential combinations of the embodiments, modes, options, examples, and preferred aspects herein. All patents and publications cited herein are incorporated herein by reference for specific teachings as stated, unless otherwise specifically provided for.

[0192] Examples

[0193] The present invention is more fully illustrated by the following examples, which are presented to illustrate the invention and should not be construed as limiting the invention. Unless otherwise specified, all parts and percentages are by weight, and all weight percentages are expressed on a dry basis excluding moisture content unless otherwise indicated.

[0194] Manufacture of monolithic catalyst products

[0195] Example 1 (Reference Article)

[0196] Zeolite ferrierite material (FER) was initially wet-impregnated with a diluted Pd(NO3)2 solution, dried in air at 110°C for 2 hours, and then calcined in air at 550°C for 1 hour. A diluted Zr acetate solution was prepared, to which the calcined Pd / FER powder was added to form a slurry suspension with a solid content of approximately 50%. The slurry was milled until a final particle size D90 of 10 to 12 μm was reached. Subsequently, the slurry was coated onto a 400 / 4 honeycomb substrate to a solid content of 42 to 46%. After drying, the catalyst was calcined in air at 590°C for 1 hour. The Pd loading was 80 g / ft². 3 was, and the zeolite washcoat loading was 2.5 g / in 3 It was, and the ZrO2 loading generated after calcination was about 5% of the washcoat composition.

[0197] Example 2

[0198] Zeolite ferrierite material (FER) was initially wet-impregnated with a solution of Ba(OAc)2, then dried (110°C / 2h) and calcined in air (590°C / 4h). The weight% of Ba varied in the range of 0.45 to 1.5%. The resulting Ba-FER material was further impregnated with a Pd(NO3)2 solution, then dried in air at 110°C / 2h, and subsequently calcined in air at 550°C for 1 hour. A diluted Zr acetate solution was prepared, to which the calcined Pd / BEA powder was added to form a slurry suspension with a solid content of approximately 50%. The slurry was milled until the final particle size D90 reached 10 to 12 μm. Subsequently, the slurry was coated onto a 400 / 4 honeycomb substrate with a solid content of 42 to 46%. After drying, the catalyst was calcined in air at 590°C for 1 hour. The Pd loading was 80 g / ft². 3 was, and the zeolite washcoat loading was 2.5 g / in3 It was.

[0199] Example 3

[0200] Zeolite ferrierite material (FER) was initially wet-impregnated with a solution of Sr(OAc)2, then dried (110°C / 2h) and calcined in air (590°C / 4h). The weight% of Sr relative to FER was approximately 1%. The resulting Sr-FER material was further impregnated with a Pd(NO3)2 solution, then dried in air at 110°C / 2h, and subsequently calcined in air at 550°C for 1 hour. A diluted Zr acetate solution was prepared, to which calcined Pd / BEA powder was added to form a slurry suspension with a solid content of approximately 50%. The slurry was milled until the final particle size D90 reached 10 to 12 μm. Subsequently, the slurry was coated onto a 400 / 4 honeycomb substrate with a solid content of 42 to 46%. After drying, the catalyst was calcined in air at 590°C for 1 hour. The Pd loading was 80 g / ft². 3 was, and the zeolite washcoat loading was 2.5 g / in 3 It was.

[0201] Example 4

[0202] The zeolite ferrierite material (FER) was initially wet-impregnated with a solution of La(NO3)3, then dried (110°C / 2h) and calcined in air (590°C / 4h). The weight% of La relative to FER was approximately 1.3%. The resulting La-FER material was further impregnated with a Pd(NO3)2 solution, then dried in air at 110°C / 2h, and subsequently calcined in air at 550°C for 1 hour. A diluted Zr acetate solution was prepared, and the calcined Pd / BEA powder was added to it to form a slurry suspension with a solid content of approximately 50%. The slurry was milled until the final particle size D90 reached 10 to 12 μm. Subsequently, the slurry was coated onto a 400 / 4 honeycomb substrate with a solid content of 42 to 46%. After drying, the catalyst was calcined in air at 590°C for 1 hour. The Pd loading was 80 g / ft². 3 was, and the zeolite washcoat loading was 2.5 g / in 3 It was.

[0203] Example 5 (LT-NA / DOC, see reference)

[0204] An LT-NA bottom layer was prepared similarly to Example 1. For the DOC top layer, a 5% SiO2-Al2O3 material was initially wet-impregnated with a diluted Pt-amine complex solution and then added to a diluted Pd nitrate solution to form a slurry suspension. The pH of the slurry suspension was adjusted to 4 to 5 using diluted HNO3. The slurry was milled to D90 = 12–15 μm, and then beta-zeolite and alumina binder materials (3.5% of the total washcoat solids) were added. Subsequently, the slurry was coated onto the LT-NA bottom layer to a solid content of 25 to 30%. After drying, the sample was calcined in air at 590°C for 1 hour. The Si-alumina loading was 0.75 g / in 3 was, and the beta zeolite loading was 0.35 g / in 3 was, and the PGM loading was 36 g / ft3 It was, and the Pt / Pd weight ratio was 1 / 2.

[0205] Example 6 (LT-NA / DOC, having Ba)

[0206] An LT-NA bottom layer was prepared similarly to Example 2. A DOC layer was prepared similarly to Example 5.

[0207] Example 7 (LT-NA / DOC, Si-containing)

[0208] An LT-NA bottom layer was prepared similarly to Example 3. A DOC layer was prepared similarly to Example 5.

[0209] Example 8 (LT-NA / DOC, La-containing)

[0210] An LT-NA bottom layer was prepared similarly to Example 4. A DOC layer was prepared similarly to Example 5.

[0211] Example 9. Evaluation of monolithic catalyst products

[0212] Monolithic catalyst components were tested in a diesel vehicle simulator for both steady-state and transient tests. In the steady-state test, the gas mixture consisted of 100 ppm NO, 250 ppm C2H4, 500 ppm CO, 5% H2O, 10% O2, 5% CO2, and balanced N2. The catalyst dimensions were 1x1x3", and the space velocity was 30,000 h -1 The temperature was maintained constant. The catalyst was first treated at 500°C / 5 min in an O2 / H2O / CO2 / N2 mixture, followed by adsorption at 100°C for 10 min in the entire mixture; desorption was performed at 100°C to 500°C in the O2 / H2O / CO2 / N2 mixture at a ramp rate of 20°C / min. The adsorption-desorption test was performed three times for each article.

[0213] In the case of the transient FTP test, the feed composition originated from a diesel engine, and the inlet NO xOnly NO was used for the supply. Each catalyst was pretreated in situ at 550°C for 5 minutes in 10% O2 / 5% H2O / 5% CO2 / N2, followed by three consecutive FTP cycles. Cold start NO x The adsorption efficiency is the adsorbed NO from startup until the point where the inlet temperature first reaches 200℃. x It was defined as a percentage of.

[0214] Adsorption-desorption profiles for Examples 1 to 4, hydrothermally aged (750°C / 80h), are illustrated in FIG. 5. Examples 2 (+Ba) and 3 (+Sr) are similar to NO of the reference article (Example 1). x Adsorption activity was exhibited. During desorption, Examples 2 and 3 showed initial NO x The desorption was shifted to a higher temperature, and the intensity of the second desorption peak increased at approximately 1400 seconds (365°C). Although we do not wish to be bound by theory, these observations suggest that Ba and Sr NO x It does not significantly affect adsorption, and instead NO x It is suggested to shift the desorption to a higher temperature range. Example 4 (+La) shows higher adsorption and desorption NO compared to Reference Example 1 without significantly changing the desorption temperature. x All capacities were displayed.

[0215] Desorbed NO for all of the degreened (calcined in air at 800°C / 2h) and hydrothermal aged (750°C / 80h) Examples 1 to 4 x The amounts were compared over three consecutive cycles (Fig. 6). Example 4 showed higher NO after both degrading and aging. x The capacity was expressed. While we do not wish to be bound by theory, these observations suggest that La not only increases the number of ion-exchanged Pd sites but also preserves these sites during aging.

[0216] The data in Fig. 7 shows that Ba concentrations in the range of 0.5 to 1.5% are NOx It did not affect adsorption, and an increase in Ba concentration NO x It shows that the detachment was gradually moved to a higher temperature.

[0217] FTP NO during cold start for aged LT-NA single catalysts (Examples 1 to 4) and LT-NA / DOC combination catalysts (Examples 5 to 8) x The adsorption efficiency is provided in Fig. 8. In both cases, the addition of alkaline earth elements (Ba, Sr) or rare earth elements (La) resulted in enhanced NO x Adsorption activity was exhibited. Although I do not wish to be bound by theory, it is believed that the addition of alkaline earth or rare earth elements better preserves ion-exchanged Pd sites after prolonged hydrothermal aging.

[0218] The effect of the second metal additive in the LT-NA / DOC catalyst on THC conversion in the FTP cycle is shown in Fig. 9. The new catalyst exhibited the same THC conversion. After aging, the catalysts of Examples 6 to 8 showed improved THC conversion efficiency in FTP.

[0219] A comparison of the CO-DRIFTS spectra of the degraded and aged Example 4 versus Reference Example 1 is provided in FIG. 10. In both cases, the higher Pd signal, the ion-exchanged Pd 2+ Both single Pd(0) atoms were detected in Example 4, which suggests higher Pd dispersion in the zeolite promoted by the addition of La.

Claims

Claim 1 Low temperature NO comprising a zeolite containing at least a first metal component and a second metal component together x An adsorbent (LT-NA) composition, wherein the first metal component comprises palladium, the second metal component is selected from the group consisting of an alkaline earth metal component, an oxide of an alkaline earth metal component, a rare earth metal component, an oxide of a rare earth metal component, and combinations thereof, and more than 50% of the ion-exchange sites of the zeolite are exchanged with palladium ions. Claim 2 LT-NA composition according to claim 1, wherein the second metal component is an alkaline earth metal component or an oxide of an alkaline earth metal component. Claim 3 LT-NA composition according to paragraph 2, wherein the alkaline earth metal component comprises magnesium, calcium, strontium, barium, or oxides of magnesium, calcium, strontium, barium, or a combination thereof. Claim 4 LT-NA composition according to claim 1, wherein the second metal component is a rare earth metal component or an oxide of a rare earth metal component. Claim 5 ◈Claim 5 was abandoned upon payment of the registration fee.◈ The LT-NA composition according to Claim 4, wherein the rare earth metal component comprises an oxide of Ce, La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, or an oxide of Ce, La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu, or a combination thereof. Claim 6 LT-NA composition according to claim 1, wherein at least a portion of the palladium is ion-exchanged in the zeolite. Claim 7 The LT-NA composition of claim 1, wherein the palladium is present in an amount of 0.01 wt% to 10 wt% based on the weight of the zeolite and calculated as elemental palladium. Claim 8 An LT-NA composition according to claim 1, wherein the second metal component is present in a weight ratio to the first metal component of 0.1 to 2, calculated as the metal for the second metal component. Claim 9 An LT-NA composition according to claim 1, wherein the second metal component is present in an amount of 0.1% to 10% by weight based on the total weight of the zeolite and calculated as a metal. Claim 10 LT-NA composition according to claim 1, wherein the zeolite is an aluminosilicate zeolite having a silica-to-alumina ratio (SAR) of 5 to 100. Claim 11 In claim 10, the aluminosilicate zeolite is an LT-NA composition having a SAR of 10 to 40. Claim 12 ◈청구항 12은(는) 설정등록료 납부시 포기되었습니다.◈ 제1항에 있습니다 제올라이트는 ABW, ACO, AEI, AEL, AEN, AET, AFI, AFN, AFO, AFR, AFS, AFT, AFX, AFY, AHT, APC, APD, ASV, ATN, ATO, ATS, ATT, ATV, AVLAW, AW, BEC, BEC, BEC BOF, BOG, BOZ, BPH, BRE, BSV, CAN, CAS, CDO, CFI, CGF, CGS, CHA, CHI, CLO, CON, CZP, DAC, DDR, DFO, DFT, DON, EAB, EDI, EEI, EMT, EON, EPI, ERI, ESV, ETR, EU, GOS, FIS, FIS, FIS, GME, GME GON, GOO, HEU, IFR, IFY, IHW, IMF, IRN, ISV, ITE, ITG, ITH, ITW, IWR, IWS, IWV, IWW, JBW, JRY, JSR, JST, KFI, LAU, LEV, LOV, LTA, LTF, LTL, LTN, LTN, MAZ, MFI, MFI, MFI, MFI, MFI I, MOR, MOZ, MRE, MSE, MTF, MTT, MVY, MTW, MWF, MWW, NAB, NAT, NES, NPO, NPT, NSI, OBW, OFF, OKO, OSI, OSO, OWE, PAR, PAU, PCR, PHI, PON, PUN, RHO, RON, RON, RTH, RTH, RTH, RTH RWY, SAF, SAO, SAS, SAT, SAV, SBE, SBS, SBT, SCO, SEW, SFE, SFF, SFG, SFH, SFN, SFO, SFS, SFW, SGF, SIV, SOF, SOS, SSF, SSY, STF, STI, STO, STT, STS, SAT, STER, STER, TVR, TVR, TSC TUN, UEI, UFI, UOS, USI, UTL, UWY, VET, VFI, VNI, VSV, WAY, WHEN, YUG, ZONE,LT-NA composition having a skeletal structure type selected from the group consisting of mixtures thereof or intergrowth. Claim 13 The LT-NA composition according to claim 1, wherein the zeolite has a skeletal structure type selected from the group consisting of BEA, CHA, FER, MFI, and FAU. Claim 14 The LT-NA composition according to claim 1, wherein the zeolite is selected from the group consisting of beta zeolite, cabazerite, ferrierite, mordenite, ZSM-5, and zeolite Y. Claim 15 LT-NA composition according to claim 1, wherein the zeolite is ferrierite. Claim 16 ◈Claim 16 was abandoned upon payment of the registration fee.◈ In Claim 1, the LT-NA composition is formed from an exhaust gas stream at a temperature of 30°C to 200°C, wherein NO present in the exhaust gas stream x Based on the total amount of NO x NO in an amount of at least 30 to 100% of the theoretical amount based on a 1:1 molar ratio of / Pd x LT-NA composition that adsorbs components. Claim 17 In claim 1, the LT-NA composition at a temperature of 170°C to 400°C, NO adsorbed on the LT-NA composition x NO in an amount of at least 50 to 100 weight percent based on the total amount of ingredients x LT-NA composition that releases components back into the exhaust gas stream. Claim 18 ◈Claim 18 was abandoned upon payment of the registration fee.◈ In Claim 1, the LT-NA composition is the first NO x Having an adsorption capacity value, and after hydrothermal aging at 750℃ for a period of 2 to 80 hours, the second NO x Having an adsorption capacity value; and the second NO x The adsorption capacity value is the above first NO x LT-NA composition having an adsorption capacity value equal to or greater than that of the adsorption capacity. Claim 19 In Clause 18, the above 2 NO x An LT-NA composition having an improved adsorption capacity compared to an LT-NA composition comprising a zeolite that includes a first metal component and does not include a second metal component. Claim 20 An LT-NA article for treating an exhaust stream of an internal combustion engine, comprising: a substrate having an inlet end and an outlet end defining the entire length; and a first washcoat comprising an LT-NA composition of any one of claims 1 to 19 disposed on at least a portion thereof. Claim 21 An LT-NA article according to claim 20, further comprising a second washcoat comprising a diesel oxidation catalyst (DOC) composition disposed on at least a portion of the above description. Claim 22 In claim 21, the DOC composition comprises a platinum group metal (PGM) component supported on one or more refractory metal oxide support materials, LT-NA article. Claim 23 In paragraph 22, the above PGM component is an LT-NA article comprising platinum and palladium. Claim 24 In paragraph 22, the refractory metal oxide support material is an LT-NA article, which is alumina or gamma alumina doped with 2% to 10% SiO2. Claim 25 In claim 21, the above DOC composition is an LT-NA article further comprising a beta zeolite without any PGM paper. Claim 26 An LT-NA article according to claim 21, wherein the first and second washcoats exist in a layered configuration, the first washcoat is disposed directly on a substrate, and the second washcoat is disposed on at least a portion of the first washcoat. Claim 27 An LT-NA article according to claim 21, wherein the first and second washcoats exist in a layered configuration, the second washcoat is disposed directly on a substrate, and the first washcoat is disposed on at least a portion of the second washcoat. Claim 28 An LT-NA article according to claim 21, wherein the first washcoat and the second washcoat are combined and disposed on a substrate as a single homogeneous layer. Claim 29 An LT-NA article according to claim 21, wherein the first and second washcoats exist in a zoned configuration, the first washcoat is disposed on a catalyst substrate for a length of 10% to 70% of the total length from the inlet end; and the second washcoat is disposed on a catalyst substrate for a length of 30% to 90% of the total length from the outlet end. Claim 30 In claim 20, the above description comprises a honeycomb substrate in the form of a wall-flow filter or a flow-through substrate, an LT-NA article. Claim 31 An exhaust gas treatment system comprising the LT-NA article of claim 20, positioned downstream of an internal combustion engine and fluidly connected thereto. Claim 32 In Clause 31, lean NO x Lean Trap (LNT), Selective Catalytic Reduction (SCR) catalyst, ammonia or ammonia precursor injection component, Catalytic Soot Filter (CSF), or Ammonia Oxidation (AMO x An exhaust gas treatment system comprising one or more additional catalysts. Claim 33 NO in exhaust gas streams from internal combustion engines x A method comprising the step of contacting the exhaust gas stream with the LT-NA article of claim 20 as a method of reducing the level. Claim 34 In paragraph 33, the contacting step is a step of continuously passing the exhaust gas stream to contact the LT-NA article, wherein the exhaust gas stream is at an initial temperature of 150°C or lower and is gradually heated during additional engine operation; NO from the exhaust gas stream until the exhaust gas stream reaches a predetermined temperature x As a step of adsorbing and storing, the NO x The step of discharging into the exhaust gas stream exiting the LT-NA article; and as the temperature of the exhaust gas stream increases and the downstream catalytic material is heated to an operating temperature of 200 to 450°C, NO x A method comprising the step of continuously passing the exhaust gas stream exiting the LT-NA article to contact at least one downstream catalytic material for the removal of components. Claim 35 NO of LT-NA composition x Adsorption / Desorption Profiles and NO of LT-NA Composition x A method for controlling one or both of a desorption temperature range, wherein the LT-NA composition comprises a zeolite comprising a first metal component and a second metal component, wherein the first metal component comprises palladium, and the second metal component is selected from the group consisting of an alkaline earth metal component, an oxide of an alkaline earth metal component, a rare earth metal component, an oxide of a rare earth metal component, and combinations thereof, wherein more than 50% of the ion-exchange sites of the zeolite are exchanged with palladium ions, and the method comprises selecting the second metal component and its loading. Claim 36 In Clause 35, the above NO x A method in which the desorption temperature range is 150, 175, 200, 225, or 250 to 275, 300, 325, 350, or 400°C.

Images