Method for forming a catalyst article

Abstract

The present invention provides a method for forming a catalyst article suitable for use in the selective catalytic reduction of nitrogen oxides in exhaust gas, and also provides a catalyst article. [Solution] This disclosure relates to (a) H + Form or NH4 + The present invention relates to a method for forming a catalyst article, comprising: (a) mixing together crystalline micropore or medium-pore molecular sieves, an insoluble active metal precursor, an inorganic matrix component, an organic additive, an aqueous solvent, and optionally inorganic fibers to form a plastic mixture having a solid content of more than 50% by weight; (b) molding the plastic mixture into a molded article; and (c) firing the molded article to form a solid catalyst. The present disclosure further relates to catalyst articles, in particular catalyst articles suitable for use in the selective catalytic reduction of nitrogen oxides and exhaust systems.

Description

[Technical Field]

[0001] The present invention relates to a method for forming a catalyst article. In particular, the present invention relates to nitrogen oxides (NOx) in exhaust gas. x This relates to a method for forming a catalyst article suitable for use in selective catalytic reduction of ). [Background technology]

[0002] Numerous catalytic converters are manufactured each year for use in treating emissions from mobile and stationary power sources. Catalytic converters for automotive use typically comprise an extruded ceramic honeycomb monolith with channels for exhaust gas flow. The channels in the monolith may be coated with a catalytic activator (known as a “wash coat”). Alternatively, the extruded monolith itself may be formed from a catalytic activator (referred to as a “fully activated extruded product” or “extruded catalyst”).

[0003] To produce fully activated extruded products, the catalytic active component is contained in an extrusion composition whose fluid properties are set to be suitable for the extrusion process. This extrusion composition is highly plastic (i.e., easily moldable) and viscous. To impart the desired fluid properties to the extrusion composition and the mechanical properties to the extruded product, a binder or additive is typically added to the extrusion composition. This plastic composition is then subjected to an extrusion molding process, for example, to produce a honeycomb body. The resulting so-called "green" body is then subjected to high-temperature calcination to form the final extrusion catalyst.

[0004] The fully activated extruded product generally includes a honeycomb-shaped integral structure having parallel channels of uniform size extending from a first end to a second end of the product. Generally, the channels are open at both ends of the first and second ends, forming a so-called "flow-through" structure. Alternatively, the channels may be sealed with suitable ceramic cement at the first upstream end, or they may not be sealed at the first upstream end but sealed at the second downstream end, forming a so-called wall-flow filter.

[0005] Nitrogen oxides (NOx) produced by ammonia (NH3-SCR) x Selective catalytic reduction of NOx is used for vehicles such as automobiles, trucks, locomotives, and ships, and for stationary and mobile engines, primarily diesel engines, to remove exhaust gases. x This is considered the most practical and efficient technique for mitigating [the problem].

[0006] Known SCR (selective catalytic reduction) catalysts include molecular sieves. Useful molecular sieves include crystalline or quasicrystalline materials, such as aluminosilicates (zeolites) or silicoaluminophosphates (SAPO). Such molecular sieves are constructed of, for example, ring-linked repeating SiO4, AlO4, and optionally PO4 tetrahedral units to form a framework with regular intracrystalline cavities and channels of molecular size. The specific arrangement of the tetrahedral units (ring members) gives rise to the molecular sieve framework, and by convention, each unique framework is assigned a unique three-letter code (e.g., "CHA") by the International Zeolite Association (IZA). Examples of molecular sieve skeletons that are known SCR catalysts include the skeleton codes CHA (chabazite), BEA (beta), MOR (mordenite), AEI, MFI, and LTA.

[0007] Molecular sieves (e.g., zeolites) can also be classified by pore size, for example, the maximum number of tetrahedral atoms present in the molecular sieve's framework. As defined herein, “small-pore” molecular sieves, such as CHA, have a maximum ring size of 8 tetrahedral atoms, while “medium-pore” molecular sieves, such as MFI, have a maximum ring size of 10 tetrahedral atoms, and “large-pore” molecular sieves, such as BEA, have a maximum ring size of 12 tetrahedral atoms. Small-pore and medium-pore molecular sieves, in particular small-pore molecular sieves, are preferred for use in SCR catalysts because they can provide, for example, improved SCR performance and / or improved hydrocarbon resistance.

[0008] Molecular sieve catalysts can be enhanced with metals. Examples of metal-enhanced molecular sieve catalysts include iron, copper, and palladium-enhanced molecular sieves, where the metal can be supported within the molecular sieve. In metal-supported molecular sieves, the supported metal is of the "extra-skeleton metal" type, i.e., a metal present within and / or on at least a portion of the molecular sieve surface, and does not contain atoms that constitute the molecular sieve skeleton. For example, iron and copper-supported small-pore and medium-pore zeolites are known to be usable as SCR catalysts.

[0009] Several methods for preparing metal-supported molecular sieves, particularly metal-supported zeolites, have been described in the literature. Direct synthesis of metal-supported zeolites is a complex process and depends on the synthesis conditions (see M. Moliner, ISRN Materials Science, 2012, Article ID 789525). As an alternative, commercially available zeolite supports are used, and then the metal is added by post-synthesis treatment of the zeolite, such as wet impregnation, wet ion exchange, or solid ion exchange.

[0010] In known wet ion exchange methods for adding metals to molecular sieves (e.g., zeolites), soluble metal salts, such as metal acetates, metal sulfates, or metal chlorides, are typically used as active metal precursors, which react with the molecular sieves in aqueous solution. To facilitate ion exchange, these processes typically require a heating step, in which the mixture may be heated to a temperature in the range of 70-80°C for up to several hours. Furthermore, the resulting metal-supported molecular sieves may require additional processing steps (e.g., filtering, evaporation, spray drying, calcination, etc.) before they can be used as an extrusion paste to form fully active extruded products. Furthermore, it became clear that when certain metal acetate salts (e.g., copper acetate) are used in the preparation of metal-supported molecular sieves (e.g., metal-supported zeolites) used as SCR catalysts, any residual metal acetate salts remaining after calcination can have a poisoning effect on ammonia slip catalysts (ASCs) used downstream of or near the SCR catalyst.

[0011] The present invention provides an improved process for producing extruded catalyst articles using metal-supported micropore or medium-pore crystalline molecular sieves as catalyst activators.

[0012] A method for forming a catalyst article according to a first aspect of this disclosure, the method is: (a) At least the following components: (i)H + Form or NH4 + A crystalline molecular sieve with small or medium pores, (ii) an insoluble active metal precursor, (iii) Inorganic matrix component, (iv) Organic additives and, (v) Forming a plastic mixture by mixing an aqueous solvent with the other, The mixture has a solid content of more than 50% by weight (based on the total weight of the mixture), (b) Molding a plastic mixture into a molded article, (c) firing the formed article to produce a solid catalyst body, is provided.

[0013] Advantageously, it has been found that the heat used to fire the formed article can be utilized to promote metal loading onto the molecular sieve. Thereby, no heating step during the wet ion exchange or impregnation process is necessary and no expensive high-temperature heat-resistant equipment may be required. Further, the long reaction times typical of the wet ion exchange or impregnation process and / or energy- and labor-intensive processes such as spray drying can be avoided. Thereby, the method according to the first aspect can be more efficient and economical.

[0014] Furthermore, it has been found that the mixture produced in step (a) of the method according to the first aspect can be used directly as an extrusion paste without any additional processing steps. In particular, the method of the first aspect can reduce the total amount of water consumed in manufacturing an extruded catalyst comprising a metal-loaded microporous or mesoporous molecular sieve. This is because conventionally, the powdery form of the microporous / mesoporous molecular sieve before loading has been used and the powdery form has been produced by a wet process followed by drying and / or firing.

[0015] And further, it has been found that the catalyst produced by the process according to the first aspect can provide at least equivalent SCR activity to a catalyst comprising a metal-loaded microporous / mesoporous molecular sieve (e.g., metal-loaded zeolite) produced by wet ion exchange or impregnation. Moreover, it has also been found that poisoning of the associated ammonia slip catalyst can be reduced as compared to an SCR catalyst comprising a metal-loaded crystalline molecular sieve produced using a metal acetate salt as an active metal precursor.

[0016] According to a second aspect of the present disclosure, a catalyst article obtained or obtainable by the method of the first aspect is provided.

[0017] According to a third aspect of the present disclosure, an exhaust system is provided, the exhaust system comprising a nitrogen-based reducing agent source and an injector for injecting the nitrogen-based reducing agent into the flowing exhaust gas, the injector being disposed upstream of the catalyst article according to the second aspect.

Brief Description of the Drawings

[0018] [Figure 1] A graph showing NOx conversion obtained by a catalyst produced according to a first aspect of the present disclosure, compared with a catalyst produced by a conventional method. [Figure 2] A graph showing N2O selective activity obtained by a catalyst produced according to a first aspect of the present disclosure, compared with a catalyst produced by a conventional method. [Figure 3] A graph showing NOx conversion obtained by a catalyst produced according to a first aspect of the present disclosure, compared with a catalyst produced using a soluble active metal precursor. [Figure 4] A graph showing N2O selective activity obtained by a catalyst produced according to a first aspect of the present disclosure, compared with a catalyst produced using a soluble active metal precursor.

Embodiments for Carrying Out the Invention

[0019] The present disclosure will now be further described. In the following sections, different aspects / embodiments of the present disclosure are more particularly defined. Each such aspect / embodiment, unless otherwise explicitly indicated, can be combined with any other aspect / embodiment or aspects / embodiments. In particular, any feature shown as being preferred or advantageous can be combined with any other feature or features shown as being preferred or advantageous.

[0020] Furthermore, as used herein, the term "comprising" can be exchanged with the definitions "consisting essentially of" or "consisting of". The term "comprising" is intended to mean that the specified elements are essential, but other elements may be added and still form a configuration within the scope of the claims. The term "consisting essentially of" limits the scope of the claims to the specified materials or steps and those that do not substantially affect the basic and novel characteristics of the claimed invention. The term "consisting of" closes the claims against including materials other than those recited, usually excluding impurities associated therewith.

[0021] Crystalline molecular sieves are typically composed of aluminum, silicon, and / or phosphorus. Crystalline molecular sieves generally have a three-dimensional arrangement (e.g., framework) by repeating SiO4, AlO4, and optionally PO4 tetrahedral units bonded by sharing of oxygen atoms. Microporous molecular sieves have a ring size of up to 8 tetrahedral atoms. Mesoporous molecular sieves have a ring size of up to 10 tetrahedral atoms.

[0022] In relation to molecular sieves, the term "H + form" refers to a molecular sieve having an anionic framework in which the charge of the framework is balanced by a proton (i.e., H + cation).

[0023] In relation to molecular sieves, the term "NH4 + form" refers to a molecular sieve having an anionic framework in which the charge of the framework is balanced by an ammonium cation (NH4 + cation).

[0024] When the crystalline molecular sieve has an aluminosilicate skeleton, the molecular sieve is preferably a zeolite.

[0025] When a crystalline molecular sieve is a microporous molecular sieve, the microporous molecular sieve may have a skeleton selected from the group of skeleton types consisting of ACO, AEI, AEN, AFN, AFT, AFX, ANA, APC, APD, ATT, CDO, CHA, DDR, DFT, EAB, EDI, EPI, ERI, GIS, GOO, IHW, ITE, ITW, KFI, LEV, LTA, MER, MON, NSI, OWE, PAU, PHI, RHO, RTH, SAT, SAV, SFW, SIV, THO, TSC, UEI, UFI, VNI, YUG, and ZON, as well as mixtures thereof and / or intercrystals. Preferably, the microporous molecular sieve has a skeleton selected from the group of skeleton types consisting of AEI, AFT, AFX, CHA, DDR, ERI, KFI, LEV, LTA, SFW, and RHO. More preferably, the small-pore crystalline molecular sieve has a skeletal structure that is AEI, AFX, CHA, LTA, ERI, or AEI-CHA intercrystal.

[0026] When the crystalline molecular sieve is a medium-pore molecular sieve, the medium-pore molecular sieve can be selected from the group of skeletal types consisting of AEL, AFO, AHT, BOF, BOZ, CGF, CGS, CHI, DAC, EUO, FER, HEU, IMF, ITH, ITR, JRY, JSR, JST, LAU, LOV, MEL, MFI, MFS, MRE, MTT, MVY, MWW, NAB, NAT, NES, OBW, PAR, PCR, PON, PUN, RRO, RSN, SFF, SFG, STF, STI, STT, STW, -SVR, SZR, TER, TON, TUN, UOS, VSV, WEI, and WEN, as well as mixtures and / or intercrystals thereof. Preferably, the medium-pore crystalline molecular sieve is selected from the group of skeletal types consisting of FER, MEL, MFI, STI, and STT.

[0027] Preferably, the crystalline molecular sieve is a small-pore zeolite having a skeletal structure of CHA, AEI, AFX, LTA, or ERI.

[0028] When the crystalline molecular sieve is a zeolite, the silica-to-alumina ratio (SAR) of the zeolite can be 5 to 200, preferably 5 to 100, and more preferably 10 to 80. For example, the silica-to-alumina ratio (SAR) of the zeolite can be 5 to 30.

[0029] If the crystalline molecular sieve is SAPO, the SAPO may have a silicon content in the range of 5 to 30% by weight, preferably 8 to 16% by weight (based on the total weight of the molecular sieve).

[0030] Crystalline small-pore or medium-pore molecular sieves are preferably powdery crystalline molecular sieves (i.e., particulate), where the particles contain individual crystals, aggregates of crystals, or combinations thereof. When measured by scanning electron microscopy (SEM), crystalline molecular sieves may have an average crystal size of 0.5 μm or more, preferably about 0.5 to about 15 μm, for example, about 0.5 to 10 μm, about 0.5 to about 5 μm, about 1 to about 5 μm, or about 2 to about 5 μm.

[0031] The powdery crystalline molecular sieve preferably has a D90 particle size of less than about 30 μm. The powdery crystalline molecular sieve preferably has a D99 particle size of less than about 50 μm. As used herein, the terms "D90 particle size" and "D99 particle size" refer to the particle size distribution. The D90 particle size value corresponds to the following particle size values ​​in which 90% by volume of the total particles in a particular sample are present. The D99 particle size value corresponds to the following particle size values ​​in which 99% by volume of the total particles in a particular sample are present. The D90 and D99 particle sizes can be determined using laser diffraction (for example, using a Malvern Mastersizer 2000).

[0032] If desired, before forming the plastic mixture in step a) of the method of the first embodiment, the molecular sieve may undergo particle size reduction treatment such as jet grinding, wet grinding, or steam-assisted jet grinding.

[0033] The components mixed together in step (a) of the first embodiment are H + or NH4 + It may contain two or more crystalline micropore or medium-pore molecular sieves of any form. Thus, the solid catalyst formed in step (c) may contain two or more different types of metal-supported molecular sieves.

[0034] As used herein, “active metal precursor” refers to metals capable of supplying extra-skeleton metal to crystalline micropore or medium-pore molecular sieves. As used herein, the term “extra-skeleton metal” refers to metals present within the molecular sieve (i.e., within micropores at either ion-exchange or non-ion-exchange sites) and / or on at least a portion of the molecular sieve surface (e.g., in the form of ions or oxides) and that do not contain metal atoms in the tetrahedral units that form the framework of the molecular sieve. It will be understood that additional metal species may be present in the mixture formed in step (a) that do not themselves participate in metal loading.

[0035] The term "insoluble activated metal precursor" refers to an activated metal precursor that is not water-soluble. In particular, an insoluble activated metal precursor may have water solubility of less than 1 g / 100 mL, for example, less than 0.1 g / 100 mL or less than 0.01 g / 100 mL. Water solubility is a measure of the amount of material that dissolves in a specific volume of water at a given temperature and pressure to form a saturated solution. As used herein, in relation to an insoluble activated metal precursor, the term "water solubility" refers to the amount (in grams) of an insoluble activated metal precursor that dissolves in 100 milliliters of water (g / 100 mL) at a temperature of 20°C and 1 atmospheric pressure.

[0036] Suitable insoluble active metal precursors include certain metal salts. In particular, insoluble active metal precursors may be metal carbonates, metal hydroxides, or metal oxalates.

[0037] The insoluble active metal precursor preferably includes a metal salt that is thermally decomposed by thermal decomposition at a temperature of less than 500°C.

[0038] Insoluble active metal precursors may include transition metal salts, noble metal salts, or rare earth metal salts. For example, insoluble active metal precursors may include one or more salts of copper, manganese, nickel, cobalt, iron, palladium, platinum, cerium, yttrium, niobium, lanthanum, zinc, calcium, and magnesium, or any mixture of two or more of these.

[0039] In particular, the insoluble active metal precursor may be selected from the group consisting of copper carbonate, manganese carbonate, nickel carbonate, cobalt carbonate, iron carbonate, palladium carbonate, platinum carbonate, cerium carbonate, yttrium carbonate, niobium carbonate, lanthanum carbonate, zinc carbonate, zirconium carbonate, calcium carbonate, magnesium carbonate, copper hydroxide, manganese hydroxide, nickel hydroxide, cobalt hydroxide, iron hydroxide, palladium hydroxide, platinum hydroxide, cerium hydroxide, yttrium hydroxide, niobium hydroxide, lanthanum hydroxide, zinc hydroxide, zirconium hydroxide, calcium hydroxide, magnesium hydroxide, copper oxalate, calcium oxalate, iron oxalate, manganese oxalate, cobalt oxalate, cerium oxalate, yttrium oxalate, zinc oxalate, and any mixture of two or more of these.

[0040] Preferably, the insoluble active metal precursor may include one or more of copper(II) carbonate, copper(II) hydroxide, and copper oxalate. More preferably, the insoluble active metal precursor includes copper(II) carbonate. In one example, the insoluble active metal precursor may include a mixture of copper(II) carbonate and cerium carbonate.

[0041] In addition to the insoluble active metal precursor, the components mixed together in step (a) may further include one or more soluble (i.e., water-soluble) active metal precursors. Preferred soluble active metal precursors may include metal acetates or metal nitrates, or any mixture of two or more of these. In one example, the insoluble active metal precursor may include copper carbonate, and the soluble active metal precursor may include cerium acetate.

[0042] The relative amounts of molecular sieves and insoluble active metal precursors used in step (a) depend on the target metal load of the molecular sieves and the amount of any soluble active metal precursor used. The metal-supported molecular sieves present in the solid produced in step (c) may have a metal load of 0.1% to 10% by weight, preferably 0.1% to 7% by weight, and more preferably 0.1% to 5% by weight.

[0043] In particular, when the crystalline micropore or medium-pore molecular sieve is a zeolite, the relative amounts of the molecular sieve, insoluble active metal precursor, and optional soluble active metal precursor used in step (a) can be selected so as to provide a solid catalyst containing a metal-supported zeolite having a metal-alumina ratio in the range of 0.2 to 0.5, preferably in the range of 0.3 to 0.5.

[0044] As used herein, the term “aqueous solvent” refers to a solvent containing water. Preferably, an aqueous solvent consists essentially of water; that is, an aqueous solvent contains water, but may also contain trace amounts of non-aqueous (e.g., organic or inorganic) impurities. The water may be deionized water or desalinated water.

[0045] The solids content of the plastic mixture formed in step (a) is at least 50% by weight, preferably at least 60% by weight. "Solids content" is the proportion of solid material present in the plastic mixture, expressed based on the total weight of the mixture. In particular, the plastic mixture may be paste-like. The solids content of the mixture is preferably in the range of 60-80% by weight, more preferably in the range of 70-80% by weight. For example, the solids content of the mixture may be about 75% by weight.

[0046] The inorganic matrix components may include inert fillers (also called permanent bonders) that provide structural integrity and / or porosity to the final solid catalyst. During the firing process, the inorganic matrix components may form sintered bridges so that the solid catalyst has rigidity and mechanical strength. Some inorganic matrix components may contribute to desirable properties that aid in the manufacturing process. For example, clay, being inherently plastic, can be included in the mixture formed in step (a) to achieve or promote a desired degree of plasticity.

[0047] Preferably, the inorganic matrix component includes an alumina precursor such as boehmite or byelite, which forms alumina during calcination. Preferably, the inorganic matrix component includes boehmite.

[0048] Alternatively, the inorganic matrix component may include silica or a silica precursor, such as colloidal silica, silane, or polysiloxane.

[0049] Alternatively, the inorganic matrix component may include clay. Suitable clays include bentonite, refractory clay, attapulgate, fuller's earth, sepiolite, hectorite, smectite, kaolin, diatomaceous earth, and any two or more mixtures thereof.

[0050] Optionally, the components mixed together in step (a) may further include inorganic fibers. Suitable inorganic fibers may be selected from the group consisting of carbon fibers, glass fibers, metal fibers, boron fibers, alumina fibers, silica fibers, silica-alumina fibers, silicon carbide fibers, potassium titanate fibers, aluminum borate fibers, and ceramic fibers. An advantage is that inorganic fibers can improve the mechanical robustness of the fired product.

[0051] Organic additives are used to improve the process or to introduce desired properties into the final solid catalyst, but they are burned out during the calcination process. These materials can improve the plasticization process and / or introduce porosity into the solid catalyst. Suitable organic additives for use in step (a) of the first embodiment may include at least one of acrylic fibers (extrusion aids and pore-forming agents), cellulose derivatives (plasticizers and / or drying aids), other organic plasticizers (e.g., polyvinyl alcohol (PVA) or polyethylene oxide (PEO)), lubricants (extrusion aids), and water-soluble resins.

[0052] In some embodiments, for example, if it is desirable for the catalyst article to be multifunctional (i.e., to exhibit two or more catalytic functions), additional catalytic activators may be incorporated into the plastic mixture formed in step (a).

[0053] The proportions of the components used in step (a) can be selected such that the plastic mixture has the required solid content and the solid catalyst after the burning of the organic additive contains 55-85% by weight, preferably 60-85% by weight, of metal-supported molecular sieves and 20-40% by weight of inorganic matrix components (based on the total weight of the solid catalyst). The selection of appropriate amounts of starting materials is within the capabilities of those skilled in the art. Preferably, the proportions of the components used in step (a) are selected such that the solid catalyst produced in step (c) contains 60-85% by weight of metal-supported molecular sieves, 20-40% by weight, of inorganic matrix components and 0-10% by weight of inorganic fibers (based on the total weight of the solid catalyst).

[0054] The plastic mixture formed in step (a) is, for example, 25-70% by weight of H (based on the total weight of the plastic mixture). + or NH 4+ It may comprise a crystalline micropore or medium-pore molecular sieve, 0.06 to 8% by weight of an insoluble active metal precursor, 12 to 33% by weight of an inorganic matrix component, 0 to 8% by weight of inorganic fibers, and up to 15% by weight of an organic additive.

[0055] In step (a), the plastic mixture is formed by mixing the components together. Preferably, the mixture is substantially homogeneous, that is, the distribution of components in the mixture is substantially uniform. These components can be mixed by any preferred method. Preferably, the components are mixed by kneading.

[0056] The pH of the plastic mixture may be adjusted as needed by adding an acid or a base.

[0057] Step (a) may be carried out at ambient temperature. Preferably, step (a) is carried out at a temperature in the range of 10 to 35°C, more preferably in the range of 10 to 30°C. For example, step (a) may be carried out at a temperature in the range of 18 to 28°C.

[0058] A notable advantage of the present invention is that the plastic mixture formed in step (a) can be used directly as an extrusion paste. Therefore, the mixture formed in step a) can be used directly in step b) without any additional processing steps.

[0059] In step (b), the mixture may be molded by extrusion molding techniques well known in the art. For example, the mixture may be molded using an extrusion press or an extruder equipped with an extrusion mold.

[0060] Step (b) may be carried out at ambient temperature. Preferably, step (b) is carried out at a temperature in the range of 10 to 35°C, more preferably in the range of 10 to 30°C. For example, step (b) may be carried out at a temperature in the range of 18 to 28°C.

[0061] Most preferably, both steps (a) and (b) are carried out at a temperature in the range of 10 to 35°C, preferably 10 to 30°C, and more preferably 18 to 28°C.

[0062] Preferably, the temperature of the plastic mixture does not exceed 35°C in the step prior to firing in step (c). For example, the temperature of the plastic mixture can be maintained at 30°C or lower, or 28°C or lower, before firing in step (c).

[0063] Preferably, the molded article has a honeycomb monolithic shape. The honeycomb structure may have any size and shape as needed. Alternatively, the molded article may have other shapes, such as plates or pellets.

[0064] Prior to the firing in step (c), the molded article may be subjected to a drying process. Thus, the method of the first embodiment may further include drying the molded article formed in step (b) before carrying out step (c). Drying of the molded article may be carried out by standard techniques, including freeze-drying and microwave drying (see, for example, International Publication No. 2009 / 080155).

[0065] In step (c) of the first embodiment, the molded article formed in step (b) (optionally dried) is calcined to form a solid catalyst. The term "calcination" refers to a heat treatment process. Calcination removes any residual solvent and organic additives (e.g., by burning), thereby solidifying the molded article.

[0066] While we do not wish to be bound by any theory, it is surprising to consider that at least some metal support of small-pore or medium-pore molecular sieves may occur during the firing of molded articles. For example, solid-state ion exchange may occur during firing.

[0067] The firing of molded articles can be carried out by techniques known in the art. In particular, firing can be carried out statically or dynamically (for example, using a belt furnace).

[0068] When the molded article has the shape of a honeycomb monolith, a flow-through firing technique can be employed, in which heated gas is flowed through the channels of the honeycomb.

[0069] Preferably, the firing process (c) is 500-900 o C, preferably 600-800 o It is carried out at temperatures in the range of C.

[0070] Preferably, the molded articles are fired for a maximum of 5 hours, preferably 1 to 3 hours.

[0071] The firing process carried out in step (c) may include multiple heat treatment steps. For example, the molded article may undergo a first heat treatment at a first temperature, and a second heat treatment at a second temperature.

[0072] For example, firing may be carried out in a reducing or oxidizing atmosphere. If multiple heat treatment steps are employed, different steps may be carried out in different atmospheres.

[0073] A catalyst article according to a second aspect of this disclosure may be used for treating combustion exhaust gas flows. That is, the catalyst article can be used to treat exhaust gases from combustion processes such as internal combustion engines (either mobile or stationary), gas turbines, or power plants (e.g., coal or oil-fueled power plants). A preferred application of the catalyst article of this disclosure is in exhaust systems for automobile vehicles. In particular, the catalyst article may be used as an SCR catalyst.

[0074] In some embodiments, for example, when it is desirable for the catalyst article to be multifunctional (i.e., to exhibit two or more catalytic functions simultaneously), the method may include a further step of applying a catalyst washcoat to the catalyst article. Thus, the first embodiment of the method may further include step (d), which coats the solid catalyst produced in step (c) with a composition containing a catalytic activator. For example, this composition may include an SCR catalyst and / or an ammonia slip catalyst (ASC). Such a washcoat step may be carried out by processes well known in the art.

[0075] The catalyst article may be configured as a flow-through honeycomb monolith, where each channel is open at both ends and extends along the entire axial length of the substrate. Alternatively, the catalyst article may be configured as a filter substrate, where some channels are blocked at one end of the article and other channels are blocked at the opposite end. Such a configuration has become known in the art as a wall-flow filter. The formation of a wall-flow filter may be influenced by the preferred setting of the porosity of the catalyst article. The porosity of the final catalyst article can be controlled, for example, by incorporating an organic pore-forming component into the organic additive used in step (a) of the first embodiment.

[0076] The catalyst may be part of the exhaust gas treatment system, and the catalyst is located downstream of the nitrogen-based reducing agent source. [Examples]

[0077] The present disclosure will be further illustrated with reference to the following examples, which are illustrative and not intended to limit the present invention.

[0078] ·Comparative example A Powdered copper-exchanged SSZ-39(AEI) zeolite (pre-prepared by a wet ion exchange process, followed by spray drying and calcination) was mixed with clay minerals, powdered synthetic boehmite alumina (Pural® SB), and glass fibers (CP160, available from MUHLMEIER). This mixture was then mixed at room temperature in an aqueous solution with a pH of 4 with carboxymethylcellulose, a plasticizer / extrusion aid (Zusoplast, a mixture of oleic acid, glycol, acids, and alcohols, a trademark of Zschimmer & Schwarz GmbH & Co KG), and polyethylene oxide (Alkox® PEO). This formed a moldable paste. The moldable paste contained 64 wt% solids. The quantitative proportions of the starting materials were selected so that the final solid catalyst contained 65 wt% copper-exchanged zeolite, 25 wt% γ-Al2O3 and clay minerals, and 10 wt% glass fibers.

[0079] The moldable paste was extruded at 20°C into a flow-through honeycomb with a circular cross-section of 1 inch in diameter and a cell density of 600 cpsi (cells per square inch). The extruded honeycomb was freeze-dried at 2 millibar for several hours according to the method described in International Publication No. 2009 / 080155, and then calcined at a temperature of 600°C in a laboratory-scale muffle furnace to form a solid catalyst.

[0080] • Example 1 In place of the previously replaced copper zeolite, the corresponding H of zeolite and copper carbonate (CuCO3·Cu(OH)2) +A moldable paste was prepared according to the method used in Comparative Example A, except for the use of a specific form. All other components used in the paste preparation were identical. The amount of copper carbonate was selected to yield the same weight percent of copper as provided by the Cu-exchanged zeolite used in Comparative Example A. The proportions of the starting materials were selected to obtain a final solid catalyst containing 65 wt% copper and zeolite, 25 wt% γ-Al2O3 and clay minerals, and 10 wt% glass fibers. Subsequently, the moldable paste was extruded into a flow-through honeycomb having the same shape and dimensions as the comparative example, and then similarly dried and calcined to form a solid catalyst.

[0081] • Example 2 A solid catalyst was prepared according to the method described in Example 1, except that copper hydroxide (Cu(OH)2) was used instead of copper carbonate.

[0082] ·Comparative example B A solid catalyst was prepared according to the method described in Example 1, except that copper nitrate (Cu(NO3)2) (i.e., a soluble active metal precursor) was used instead of copper carbonate.

[0083] • Example 3 H + Except for the use of SSZ-13(CHA) as the zeolite, the solid catalyst was prepared according to the method described in Example 1.

[0084] • Catalyst testing The same volume samples from Comparative Example A and Example 1 were tested using a synthetic catalytic activity test (SCAT) apparatus. The tests involved 300 ppm NO (NO2 0%) and 300 ppm NH3 (ammonia vs. NO2). X Using an inlet gas mixture with an Ammonia to NOx ratio (ANR) of 1.0, consisting of 9.3% O2, 7% H2O, and the remainder N2, at a selected inlet gas temperature, for 120,000 h -1The tests were conducted at the following space velocity (SV). Catalyst samples were tested both in their fresh state and after aging with hot water (10 vol% H2O at 650°C for 50 hours).

[0085] The results are shown in Figures 1 and 2.

[0086] Figure 1 shows the NO obtained by each sample at the selected inlet temperature. X The conversion rate is shown, and Figure 2 shows the N2O selective activity obtained by each sample at the selected inlet temperature.

[0087] As shown in the data in Figures 1 and 2, Example 1 produced equivalent or slightly superior NO compared to Comparative Example A. X It exhibits a conversion rate and equivalent N2O selectivity. Based on the comparative catalyst performance, the catalyst prepared in Example 1 contains Cu-supported zeolite, and the resulting copper-supported zeolite is similar to that of the powdered, pre-replaced zeolite used in Comparative Example A.

[0088] One advantage is that, compared to the overall manufacturing process in Comparative Example A, the manufacturing process in Example 1 requires fewer process steps and consumes less water and energy.

[0089] The same volume of fresh samples from Examples 2 and 3 and Comparative Example B were tested using a synthetic catalyst activity test (SCAT) apparatus under the same conditions as described above.

[0090] The results are shown in Figures 3 and 4. For comparative purposes, the results obtained for Example 1 under fresh conditions were also reproduced in Figures 3 and 4.

[0091] Further aspects and embodiments of this disclosure are described in the following numbered clauses. Clause 1. A method for forming a catalyst article, (a) At least the following components: (i)H + Form or NH4+ A crystalline molecular sieve with small or medium pores, (ii) an insoluble active metal precursor, (iii) Inorganic matrix component, (iv) Organic additives and, (v) Forming a plastic mixture by mixing an aqueous solvent with the other, The mixture has a solid content of more than 50% by weight, (b) Molding a plastic mixture into a molded article, (c) A method comprising firing a molded article to form a solid catalyst. Clause 2. The components to be mixed together in step (a) further include (vi) inorganic fibers, in the manner prescribed in Clause 1. Article 3. A method for forming a catalyst article, (a) The following ingredients: (i)H + Form or NH4 + A crystalline molecular sieve with small or medium pores, (ii) an insoluble active metal precursor, (iii) Inorganic matrix component, (iv) Organic additives and, (v) an aqueous solvent, (vi) Forming a plastic mixture by arbitrarily mixing inorganic fibers together, The mixture has a solid content of more than 50% by weight, (b) Molding a plastic mixture into a molded article, (c) A method comprising firing a molded article to form a solid catalyst. Article 4. A method for forming a catalyst article, (a) The following ingredients: (i) an insoluble active metal precursor, (ii) Inorganic matrix components, (iii) Organic additives and (iv) an aqueous solvent, (v) Forming a plastic mixture by arbitrarily mixing inorganic fibers together, The plastic mixture has a solid content of more than 50% by weight, (b) Molding a plastic mixture into a molded article, (c) The process involves firing a molded article to form a solid catalyst, A method for optionally drying the molded article after step (b) and before step (c). Clause 5. The relative proportions of the components used in step (a) are selected to be in accordance with any one of Clauses 1 to 4, such that the solid catalyst formed in step (c) contains 55 to 85% by weight of metal-supported molecular sieves, 20 to 40% by weight of inorganic matrix components, and 0 to 10% by weight of inorganic fibers. Clause 6. The relative proportions of the components used in step (a) are selected to be in accordance with any one of Clauses 1 to 5, such that the solid catalyst formed in step (c) contains 60 to 85% by weight of metal-supported molecular sieves, 20 to 40% by weight of inorganic matrix components, and 0 to 10% by weight of inorganic fibers. Clause 7. The plastic mixture formed in step (a) shall contain 25-70% by weight of H (based on the total weight of the plastic mixture). + Form or NH4 + A method as specified in any one of Clauses 1 to 6, comprising a crystalline micropore or medium-pore molecular sieve of any form, 0.06 to 8% by weight of an insoluble active metal precursor, 12 to 33% by weight of an inorganic matrix component, 0 to 8% by weight of inorganic fibers, and up to 15% by weight of an organic additive. Clause 8. A crystalline molecular sieve is a small-pore molecular sieve, as specified in any one of Clauses 1 to 7. Clause 9. A small-pore molecular sieve having a skeletal structure selected from AEI, AFT, AFX, CHA, DDR, ERI, KFI, LEV, LTA, SFW, and RHO, as specified in Clause 8. Clause 10. The crystalline molecular sieve is a small-pore zeolite selected from CHA, AEI or AFX, LTA or ERI, preferably having a skeleton selected from CHA or AEI, as specified in any one of Clauses 1 to 9. Clause 11. The crystalline molecular sieve is a zeolite having a silica-alumina ratio (SAR) of 5-200, 5-100, 10-80, or 5-30, as specified in any one of Clauses 1-10. Clause 12. The crystalline molecular sieve is in particulate form and has a D90 particle size of less than 30 μm, as specified in any one of Clauses 1 to 11. Clause 13. The crystalline molecular sieve is in particulate form and has a D99 particle size of less than 50 μm, as specified in any one of Clauses 1 to 12. Clause 14. Component (i) is H + Form or NH4 + A method as defined in any one of clauses 1 to 13, comprising two or more micropore or medium-pore crystalline molecular sieves of any form. Clause 15. The insoluble active metal precursor has water solubility of less than 1 g / 100 mL, less than 0.1 g / 100 mL, or less than 0.01 g / 100 mL, as specified in any one of Clauses 1 to 14. Clause 16. The insoluble active metal precursor is selected from metal carbonates, metal hydroxides, metal oxalates, or any mixture of two or more thereof, by the method specified in any one of Clauses 1 to 15. Clause 17. The insoluble active metal precursor comprises salts of copper, manganese, nickel, cobalt, iron, palladium, platinum, cerium, yttrium, niobium, lanthanum, zinc, calcium, magnesium, or any mixture of two or more of these, as prescribed in any one of Clauses 1 to 16. Clause 18. The insoluble active metal precursor is selected from the group consisting of copper carbonate, manganese carbonate, nickel carbonate, cobalt carbonate, iron carbonate, palladium carbonate, platinum carbonate, cerium carbonate, yttrium carbonate, niobium carbonate, lanthanum carbonate, zinc carbonate, zirconium carbonate, calcium carbonate, magnesium carbonate, copper hydroxide, manganese hydroxide, nickel hydroxide, cobalt hydroxide, iron hydroxide, palladium hydroxide, platinum hydroxide, cerium hydroxide, yttrium hydroxide, niobium hydroxide, lanthanum hydroxide, zinc hydroxide, zirconium hydroxide, calcium hydroxide, magnesium hydroxide, copper oxalate, calcium oxalate, iron oxalate, manganese oxalate, cobalt oxalate, cerium oxalate, yttrium oxalate, zinc oxalate, and any mixture of two or more of these, by the method prescribed in any one of Clauses 1 to 17. Clause 19. The insoluble active metal precursor comprises one or more of copper(II) carbonate, copper(II) hydroxide, and copper oxalate, as prescribed in any one of Clauses 1 to 18. Clause 20. The insoluble active metal precursor comprises copper(II) carbonate, prepared by any one of Clauses 1 to 19. Clause 21. The insoluble active metal precursor comprises a mixture of copper(II) carbonate and cerium carbonate, prepared by any one of Clauses 1 to 20. Article 22. Insoluble active metal precursors are 500 ℃ A method specified in any one of clauses 1 to 21, comprising one or more metal salts that have been thermally decomposed by thermal decomposition at a temperature below a certain temperature. Clause 23. The method specified in any one of Clauses 1 to 22, wherein the components to be mixed together in step (a) further comprises (vii) a soluble active metal precursor. Clause 24. The aqueous solvent is essentially made from water, in the manner prescribed in any one of Clauses 1 to 23. Clause 25. The aqueous solvent is water, as specified in any one of Clauses 1 to 25. Clause 26. The method specified in any one of Clauses 1 to 25, wherein the solid content of the plastic mixture formed in step (a) is at least 60% by weight. Clause 27. The method specified in any one of Clauses 1 to 26, wherein the solid content of the plastic mixture formed in step (a) is in the range of 60 to 80% by weight, more preferably in the range of 70 to 80% by weight. Clause 28. The inorganic matrix component is boehmite and / or byelite, preferably boehmite, in the manner prescribed in any one of Clauses 1 to 27. Clause 29. The inorganic matrix component includes clay, in the manner prescribed in any one of Clauses 1 to 28. Clause 30. The clay is selected from bentonite, refractory clay, attapulgite, fuller's earth, sepiolite, hectorite, smectite, kaolin, diatomaceous earth, and any two or more mixtures thereof, in the manner prescribed in Clause 29. Clause 31. Step (a) further comprises (vi) inorganic fibers, the inorganic fibers comprising one or more of the following: carbon fibers, glass fibers, metal fibers, boron fibers, alumina fibers, silica fibers, silica-alumina fibers, silicon carbide fibers, potassium titanate fibers, aluminum borate fibers, and ceramic fibers, in the manner prescribed in any one of Clauses 1 to 30. Clause 32. The organic additive comprises at least one of acrylic fibers, cellulose derivatives, organic plasticizers, lubricants, and water-soluble resins, as specified in any one of Clauses 1 to 31. Clause 33. In step (a), the components are mixed together by kneading in any one of Clauses 1 to 32. Clause 34. Step (a) shall be carried out at ambient temperature using the method specified in any one of Clauses 1 to 33. Clause 35. Step (a) is carried out in any one of Clauses 1 to 33 by a method specified in any one of Clauses 1 to 33, at a temperature in the range of 10 to 35°C, 10 to 30°C, or 18 to 28°C. Clause 36. The plastic mixture formed in step a) is used directly in step b) by any one of Clauses 1 to 35, without any additional processing steps. Clause 37. Step (b) is carried out by extrusion molding, in any of the methods specified in any one of Clauses 1 to 36. Clause 38. Step (b) shall be carried out at ambient temperature using any one of Clauses 1 to 37. Clause 39. Step (b) is carried out in any one of Clauses 1 to 37 by a method specified in any one of Clauses 1 to 37, at a temperature in the range of 10 to 35°C, 10 to 30°C, or 18 to 28°C. Clause 40. Before firing in step (c), the temperature of the plastic mixture shall not exceed 35°C, preferably not exceeding 30°C, and more preferably not exceeding 28°C, as specified in any one of Clauses 1 to 39. Clause 41. The molded article is a honeycomb monolith, in the manner prescribed in any one of Clauses 1 to 40. Clause 42. The method specified in any one of Clauses 1 to 41, further comprising drying the molded article formed in step (b) before step (c). Clause 43. Process (c) is 500-900 ℃ The range is preferably 600 to 800. ℃ A method specified in any one of clauses 1 to 42, carried out at temperatures within the range of 42. Clause 44. In step (c), the firing is carried out for a maximum of 5 hours, preferably 1 to 3 hours, as specified in any one of Clauses 1 to 43. Clause 45. A method specified in any one of Clauses 1 to 44, wherein the solid catalyst formed in step (c) comprises a metal-supported molecular sieve. Clause 46. A method according to any one of Clauses 1 to 45, comprising a metal-supported molecular sieve, wherein the solid catalyst formed in step (c) is catalytically active for SCR. Clause 47. During process (c), metal loading of at least a portion of the molecular sieve occurs in a manner specified in any one of Clauses 1 to 46. Clause 48. Catalyst articles obtained or obtainable by any one of Clauses 1 to 47. Clause 49. A catalyst article as defined in Clause 48, configured as a flow-through honeycomb monolith or wall-flow filter. Clause 50. A catalyst article as defined in Clause 48 or 49, which is catalytically active for SCR. Clause 51. An exhaust system comprising a nitrogen-based reducing agent source and an injector for injecting the nitrogen-based reducing agent into flowing exhaust gas, wherein the injector is located upstream of the catalyst article specified in Clause 50.

[0092] To avoid any misunderstanding, all documents cited herein and the entire contents of all such documents are incorporated into this application by reference.

Claims

1. A method for forming a catalyst article, (a) at least the following components: (i) H ＋ Form or NH ４ ＋ A crystalline molecular sieve with small or medium pores, (ii) Insoluble active metal precursors, (iii) Inorganic matrix components, (iv) Organic additives and, (v) Forming a plastic mixture by mixing an aqueous solvent with the other, The mixture has a solid content of more than 50% by weight, (b) Molding the plastic mixture into a molded article, (c) A method comprising firing the molded article to form a solid catalyst.

2. The method according to claim 1, wherein the component mixed together in step (a) further comprises (vi) inorganic fibers.

3. The method according to claim 1 or 2, wherein the relative proportions of the components used in step (a) are selected such that the solid catalyst formed in step (c) comprises 60 to 85% by weight of metal-supported molecular sieves, 20 to 40% by weight of matrix components, and 0 to 10% by weight of inorganic fibers.

4. The method according to any one of claims 1 to 3, wherein the crystalline molecular sieve is a small-pore zeolite having a skeletal structure selected from CHA, AEI, or AFX, LTA, or ERI.

5. The method according to any one of claims 1 to 4, wherein the insoluble active metal precursor is selected from the group consisting of copper carbonate, manganese carbonate, nickel carbonate, cobalt carbonate, iron carbonate, palladium carbonate, platinum carbonate, cerium carbonate, yttrium carbonate, niobium carbonate, lanthanum carbonate, zinc carbonate, zirconium carbonate, calcium carbonate, magnesium carbonate, copper hydroxide, manganese hydroxide, nickel hydroxide, cobalt hydroxide, iron hydroxide, palladium hydroxide, platinum hydroxide, cerium hydroxide, yttrium hydroxide, niobium hydroxide, lanthanum hydroxide, zinc hydroxide, zirconium hydroxide, calcium hydroxide, magnesium hydroxide, copper oxalate, calcium oxalate, iron oxalate, manganese oxalate, cobalt oxalate, cerium oxalate, yttrium oxalate, zinc oxalate, and any mixture of two or more of these.

6. The method according to any one of claims 1 to 5, wherein the insoluble active metal precursor comprises one or more of copper(II) carbonate, copper(II) hydroxide, and copper oxalate.

7. The method according to any one of claims 1 to 6, wherein the aqueous solvent is water.

8. The method according to any one of claims 1 to 7, wherein the solid content of the plastic mixture formed in step (a) is at least 60% by weight, preferably in the range of 60 to 80% by weight, and more preferably in the range of 70 to 80% by weight.

9. The method according to any one of claims 1 to 8, wherein the inorganic matrix component comprises an alumina precursor and / or clay.

10. The method according to any one of claims 1 to 9, wherein the organic additive comprises at least one of acrylic fibers, cellulose derivatives, organic plasticizers, lubricants, and water-soluble resins.

11. The method according to any one of claims 1 to 10, wherein step (a) is carried out at a temperature in the range of 10 to 35°C, 10 to 30°C, or 18 to 28°C.

12. Step (b) is carried out at a temperature in the range of 10 to 35°C, 10 to 30°C, or 18 to 28°C, according to any one of claims 1 to 11.

13. A catalyst article obtained or obtainable by the method specified in any one of claims 1 to 12.

14. The catalyst article according to claim 13, which has catalytic activity against SCR.

15. An exhaust system comprising a nitrogen-based reducing agent source and an injector for injecting the nitrogen-based reducing agent into flowing exhaust gas, wherein the injector is disposed upstream of the catalyst article defined in claim 14.

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