Process for producing Fe-doped beta zeolite catalyst monolith

Abstract

A process for producing a three-dimensional porous Fe-doped beta zeolite catalyst monolith of stacked catalyst fibers, the process comprising the steps of: a) preparing a suspended paste in a liquid aqueous diluent of Fe-doped beta zeolite particles, and the suspension further comprises a binder material in a maximum amount of (50) wt%, based on the amount of the Fe-doped beta zeolite particles, and a plasticizer and a pore-forming material in a maximum amount of (10) wt%, each, based on the amount of the Fe-doped beta zeolite particles, and a peptizing agent in a maximum amount of 5 wt%, based on the amount of the Fe-doped beta zeolite particles, all the particles in the suspension have a number average particle size in the range of 0.05 to 700 m, b) extruding the paste of step a) through one or more nozzles to form fibers and depositing the extruded fibers to form a three-dimensional porous catalyst monolith precursor, c) drying the porous catalyst monolith precursor to remove the liquid diluent, d) temperature-treating the dried porous catalyst monolith precursor of step c) at a temperature in the range of 300 DEG C to 600 DEG C to form the Fe-doped beta zeolite catalyst monolith wherein the porous catalyst monolith precursor or porous catalyst monolith is not temperature-treated at a temperature above 600 DEG C, and wherein preferably in addition to copper, the porous catalyst monolith precursor or porous catalyst monolith is not temperature-treated at a temperature above 600 DEG C to form the Fe-doped beta zeolite catalyst monolith. No additional catalytically active metal, metal oxide or metal compound is applied to the surface of the Fe-doped beta zeolite particles, the catalyst monolith precursor or the Fe-doped beta zeolite catalyst monolith.

Description

[0001] This invention relates to a method for producing a three-dimensional porous Fe-doped β-zeolite catalyst bulk material for stacked catalyst fibers, the bulk material obtained therefrom, and its uses.

[0002] Inorganic catalysts are typically produced as powders and molded bodies in the form of extrusions, granules, pellets, spheres, tablets, or extruded monoliths or honeycomb structures.

[0003] Current commercially available catalyst profiles are limited by their size. The smallest commercially available size is approximately 1.2 mm (for extruders). Using smaller diameter extruders has advantages for some catalytic applications due to increased geometric surface area and shorter pore diffusion lengths. However, such smaller extruders cannot be used in commercial reactor settings due to excessively low strength and high pressure drop. For multi-tube reactors, the reactor tubes need to be filled very uniformly with catalyst material. To ensure reactor equilibrium, current catalysts rely on cut extruders or tablets to ensure uniform particle size. Similarly, loading such reactors is time-consuming, labor-intensive, and cost-intensive. There is a desire for packed reactors, especially multi-tube reactors with profiles of uniform size and shape and enhanced mechanical properties. For current Fe-doped β-zeolite catalysts (e.g., for the selective catalytic reduction of NO with NH3), x (or N2O emission reduction), such molded bodies that offer a combination of these advantages are unknown.

[0004] Fe-doped β-zeolite catalysts can be used as extrudates with standard diameters ranging from 1.2 mm to 12.0 mm. Special cross-sections such as star, trefoil, tetralobe, and annular geometries are possible. Alternatively, tablets with diameters between 1.5 and 20.0 mm are used. Different catalyst shapes result in different pressure drops in the reactor.

[0005] Compared to linearly stretched honeycomb structures, alternative processes that allow for a wider variety of shapes can be fabricated, for example, through rapid prototyping processes. For instance, the process described in US 8,119,554 involves producing molded bodies via a powder-based rapid prototyping process, in which a binder material is selectively incorporated into an inorganic catalyst powder to form a three-dimensional structure.

[0006] Another production process, commonly known as robotic casting, can be employed. In this method, a paste of catalyst material particles is extruded into strands, which are then deposited in stacked layers to form the desired three-dimensional structure. The structure is subsequently dried and heat-treated. US 7,527,671 discloses the production of renewable diesel particulate filters using a robotic casting method.

[0007] An extrusion-based 3D printing of molecular sieve zeolites for gas absorption applications is described in a contributing paper in Materials Science and Technology 2018 (MS&T18), October 14-18, 2018, pp. 33-40. Zeolites 13X and 5A, 4A and 3A were mixed with bentonite as a binder, methylcellulose as a plasticizing organic binder, and poly(vinyl) alcohol (PVA) as a co-binder. A homogeneous aqueous slurry with suitable viscosity was obtained and 3D printed to form circular grating disks or square grating designs. The 3D-printed zeolite 3A and 4A monolithic materials contained 90 wt% zeolite, 7 wt% bentonite, 2.0 wt% methylcellulose and 1.0 wt% PVA, or 95 wt% zeolite, 3 wt% bentonite, 1.5 wt% methylcellulose and 0.5 wt% PVA. It is claimed that the increased hardness value after sintering indicates better mechanical strength of the 3D printed zeolite sample, but on the other hand, the increased hardness value after sintering makes it brittle.

[0008] Catalysis Today, 216 (2013), pp. 18-23, discloses a macroporous support with a thin zeolite active layer. Three-dimensional fiber deposition allows for different architectures of the catalyst support. A wash-coating method was optimized for coating ZSM-5 on different types of supports. The fabricated catalyst was evaluated for its conversion of methanol to light olefins.

[0009] Chemical Papers, 68 (9), 1143-1153 (2014), disclosed the conversion of methanol to light olefins (MTO) using a structured catalyst. It highlighted important aspects such as the influence of coating thickness, zeolite crystal size, and support architecture on the mass transfer properties of the final catalyst. Figure 2 The pressure drop as a function of the specific geometric surface area was depicted for different shapes. For the same specific surface area, the samples exhibited varying pressure drops from high to low: spheres (filled bed), foam, three-dimensional fiber deposition (3DFD) 1-3, 3DFD 1-1, and honeycomb. The 3DFD surface was coated with ZSM-5, see Figure 3.

[0010] Int. J. Appl. Ceram. Technol., 9 [5], pp. 902-910 (2012) disclosed ceramic processing techniques for catalyst design: formation, properties and catalytic examples of ZSM-5 on 3D fiber deposition support structures. The (1.1) and (1.3.5) stackings of the 3DFD supports were disclosed.

[0011] US 2007 / 0259770 and US 2009 / 0291824 describe extruded catalyst bodies, such as honeycomb bodies, wherein the extruded paste contains a significant amount of fiber / fiber filler.

[0012] For the selective catalytic reduction of NO using NH3 x Fe-β zeolite is commonly used; see Chinese Journal of Catalysis, 37 (2016), pp. 2069-2078. β zeolite possesses a three-dimensional channel structure with 12-membered rings assembled from 4-, 5-, and 6-membered rings, making it an attractive host material for metal loading. The catalyst is used in tray form, which is pulverized to 20-40 mesh.

[0013] Methods and catalysts for the reduction of nitrogen oxides with ammonia using zeolite catalysts are described in numerous patent applications and patents, such as US 4,961,917, EP 3,708,252 A1, WO 02 / 41991, WO 03 / 022430, WO 2013 / 118064 A1, and US 2013 / 0202524 A1. The catalysts are typically used in the form of molded 1.5 to 3 mm strands, prepared by mixing a metal-loaded β-zeolite material with 20–50 wt% alumina based on 100 wt% of the resulting mixture. The molded mixture is calcined at 450°C for 4 hours to obtain the desired catalyst sample; see examples.

[0014] To achieve a high external surface area of ​​the catalyst in a fixed-bed catalytic reactor, such as for diffusion-limited reactions or high packing densities with low pore volume, the use of smaller catalyst particles is necessary. In mass-transfer-constrained reactions, smaller catalyst particles outperform larger extrusions. However, a drawback is that smaller extrusions exhibit higher pressure drops in packed beds, which limits their application in chemical reactors. Furthermore, the mechanical strength of these small extrusions is typically insufficient for forming packed-bed reactors on a commercial scale.

[0015] Current third-generation N2O emission reduction catalyst technologies utilize catalyst extrusions. Because these extrusions require shapes with high external surface areas (e.g., star-shaped), they are difficult to produce and experience high levels of mechanical wear. Furthermore, to achieve proper gas mixing, a significant portion (up to 60%) of the reactor volume is filled with packing material, allowing for a homogeneous mixture of NOx, N2O, and the reducing agent.

[0016] The object of this invention is to provide an Fe-doped β-zeolite catalyst with a high external surface area or high packing density. The catalyst structure should be mechanically stable enough to allow a packed catalyst bed to form in the reactor, exhibiting low pressure drop and low wear.

[0017] According to the present invention, this objective is achieved by a method for producing a three-dimensional porous Fe-doped β-zeolite catalyst bulk material for stacked catalyst fibers, the method comprising the following steps:

[0018] a) A suspension paste is prepared in a liquid aqueous diluent containing Fe-doped β-zeolite particles, wherein the suspension further comprises a binder material in a maximum amount of 50 wt% based on the amount of Fe-doped β-zeolite particles, a plasticizer and a pore-forming material each in a maximum amount of 10 wt% based on the amount of Fe-doped β-zeolite particles, and a solvent in a maximum amount of 5 wt% based on the amount of Fe-doped β-zeolite particles, wherein all particles in the suspension have a number-average particle size in the range of 0.05 to 700 µm.

[0019] b) Extruding the paste from step a) through one or more nozzles to form fibers, and depositing the extruded fibers to form a three-dimensional porous catalyst monolithic precursor.

[0020] c) Dry the porous catalyst precursor to remove the liquid diluent.

[0021] d) The dried porous catalyst precursor from step c) is subjected to temperature treatment in the range of 300°C to 600°C to form the Fe-doped β-zeolite catalyst precursor.

[0022] The porous catalyst precursor or porous catalyst substrate is not subjected to temperature treatment at a temperature above 600°C, and preferably, no other catalytically active metals, metal oxides or metal compounds other than copper and cobalt are applied to the surface of the Fe-doped β-zeolite particles, the catalyst precursor or the Fe-doped β-zeolite catalyst substrate.

[0023] The technical solutions described herein offer a significantly higher external surface area of ​​the active material due to the narrow diameter of the individual fibers produced by the 3D micro-extrusion shape, while allowing for excellent mixing, thus reducing reactor size requirements. This invention provides catalysts with higher performance than existing extruders, while also challenging competing monolithic coating solutions. The use of 3D micro-extrusion materials allows for the application of catalysts in units with physical limitations associated with waste gas reactor treatment, where conventional catalysts would not function effectively, thus allowing for further reductions in N2O emissions from processes and equipment that currently lack optimal or any N2O reduction units. Furthermore, 3D micro-extrusion materials allow for the application of this catalyst in mobile applications where classic extruders would result in excessively high pressure drops.

[0024] Removal of N2O and / or NO from exhaust gases from chemical plants (e.g., nitric acid or adipic acid plants), stationary generators, and mobile sources (e.g., marine engines). x This makes it possible. Marine applications, as well as nitric acid and adipic acid plants, are preferred application areas.

[0025] Fe-doped β-zeolite particles with a number-average particle size ranging from 0.5 to 500 µm can be obtained using a variety of processes, disclosed for example in US 2013 / 0202524 A1, WO 2013 / 118064, WO 03 / 022430, WO 02 / 41991, EP 3708 252 A1, and US 4,961,917. The desired or required particle size can be obtained by pulverizing or grinding the Fe-doped β-zeolite to the desired size. The particle size can be determined optically using a camsizer.

[0026] A process for producing zeolite materials having a BEA-type framework structure comprising YO2 and X2O3 according to the present invention includes the following steps:

[0027] (1) Prepare a mixture comprising one or more YO2 sources, one or more X2O3 sources, and seed crystals comprising one or more zeolite materials having a BEA-type framework structure;

[0028] (2) Crystallize the mixture obtained in step (1); and

[0029] (3) Subject the zeolite material with a BEA-type framework structure obtained in step (2) to an ion exchange process with Cu and / or Fe; wherein Y is a tetravalent element and X is a trivalent element, wherein the mixture provided in step (1) and crystallized in step (2) does not contain an organic template as a structure-directing agent, and

[0030] The total amount of Cu and / or Fe in the ion exchange material obtained in step (3), calculated based on Fe2O3 and CuO, ranges from 0.1 to 2 wt%.

[0031] Preferably, the zeolite material obtained in step (2) contains one or more alkali metals M, wherein M is selected from the group consisting of Li, Na, K, Cs, and combinations of two or more of them.

[0032] Preferably, Y is selected from the group consisting of Si, Sn, Ti, Zr, Ge, and mixtures of two or more of them.

[0033] Preferably, the one or more YO2 sources provided in step (1) comprise one or more silicates.

[0034] Preferably, in addition to the one or more silicates, the one or more YO2 sources further comprise one or more silicon dioxide.

[0035] Preferably, the mixture provided in step (1) contains water glass.

[0036] Preferably, X is selected from the group consisting of Al, B, In, Ga, and mixtures of two or more of them.

[0037] Preferably, the one or more X2O3 sources comprise one or more aluminates.

[0038] Preferably, the molar ratio of YO2 : X2O3 in the mixture from step (1) is in the range of 1 to 200.

[0039] Preferably, the amount of seed crystals included in the mixture according to step (1) ranges from 0.1 to 30 wt.% of YO2 based on 100 wt.% of one or more YO2 sources.

[0040] Preferably, the mixture according to step (1) further comprises one or more solvents.

[0041] The process for treating a gas stream containing nitrogen oxides according to the present invention includes the following steps:

[0042] (1) Provide an airflow containing one or more nitrogen oxides;

[0043] (2) Contact the gas flow provided in step (1) with a transition metal-containing zeolite material having a BEA-type framework structure to cause one or more of these nitrogen oxides to react.

[0044] The zeolite material can be obtained through a synthesis process without organic templates.

[0045] Preferably, the one or more nitrogen oxides comprise: one or more compounds selected from the group consisting of N2O, NO, NO2, N2O3, N2O4, N2O5, NO3, and mixtures of two or more thereof, preferably one or more.

[0046] A compound selected from the group consisting of N2O, NO, NO2, and mixtures of two or more thereof, wherein even more preferably, one or more nitrogen oxides comprising N2O and / or NO are present in the gas stream provided in step (1). x ,

[0047] Preferably, the gas flow provided in step (1) contains N2O in an amount ranging from 10 to 10,000 ppmv, preferably 50 to 5,000 ppmv, more preferably 100 to 3,000 ppmv, more preferably 500 to 2,000 ppmv, more preferably 700 to 1,500 ppmv, and even more preferably 900 to 1,100 ppmv.

[0048] Preferably, the airflow provided in step (1) contains NO. x The amount includes the range of 0 to 5,000 ppmv, more preferably 50 to 2,000 ppmv, more preferably 100 to 1,000 ppmv, more preferably 150 to 800 ppmv, more preferably 200 to 600 ppmv, and even more preferably 250 to 500 ppmv.

[0049] Preferably, the gas flow provided in step (1) contains N2O and NO. x Its molar ratio of NO x N2O includes a ratio of 1:50 to 5:1, preferably 1:20 to 2:1, more preferably 1:10 to 1:1, more preferably 1:5 to 1:1.5, and even more preferably 1:4 to 1:2.

[0050] Preferably, the gas flow provided in step (1) further comprises one or more reducing agents.

[0051] Preferably, the one or more reducing agents comprise one or more compounds selected from the group consisting of hydrocarbons, carbon monoxide, hydrogen, and combinations of two or more thereof, wherein the one or more reducing agents preferably comprise one or more hydrocarbons, more preferably one or more hydrocarbons selected from the group consisting of C1 to C6 alkanes, preferably C1 to C5 alkanes, wherein more preferably the one or more reducing agents comprise one or more hydrocarbons selected from the group consisting of methane, ethane, propane, and butane, wherein even more preferably the one or more reducing agents comprise methane and / or propane and / or butane, more preferably methane and / or propane, and wherein even more preferably the one or more reducing agents comprise propane.

[0052] Preferably, it is one or more reducing agents, preferably one or more hydrocarbons and one or more nitrogen oxides, preferably with N2O and / or NO. x The stoichiometric ratio is included in the range of 0.05 to 50, preferably 0.1 to 20, more preferably 0.15 to 10, more preferably 0.25 to 5, more preferably 0.35 to 2, more preferably 0.5 to 1.5, more preferably 0.65 to 1.25, and even more preferably 0.75 to 1.1.

[0053] Preferably, the reducing agent does not include ammonia and / or urea, and even more preferably, the reducing agent does not include ammonia, urea, or any derivative thereof. More preferably, the reducing agent does not include nitrogen-containing compounds in which nitrogen exists in a negative oxidation state, and even more preferably, the reducing agent does not include nitrogen-containing compounds.

[0054] Preferably, the airflow provided in step (1) contains 0% to 10% oxygen by volume, more preferably 0.5% to 8% by volume, more preferably 1% to 6% by volume, more preferably 1.5% to 5% by volume, more preferably 2% to 4% by volume, and even more preferably 2.5% to 3.5% by volume.

[0055] Preferably, the airflow provided in step (1) contains 0% to 10% H2O by volume, more preferably 0.05% to 5% by volume, more preferably 1% to 3% by volume, more preferably 0.1% to 2% by volume, more preferably 0.15% to 1% by volume, and even more preferably 0.2% to 0.5% by volume.

[0056] Preferably, the gas stream provided in step (1) comprises one or more waste gases, preferably from one or more industrial processes, and more preferably from one or more waste gases obtained in processes for producing adipic acid, nitric acid, hydroxylamine derivatives, caprolactam, glyoxal, methylglyoxal, glyoxylic acid, or in processes for burning nitrogen-containing materials, including mixtures of two or more waste gas streams from said processes, and even more preferably from one or more waste gas streams obtained in processes for producing adipic acid and / or nitric acid.

[0057] Preferably, the airflow provided in step (1) comprises one or more exhaust gases from an internal combustion engine, preferably from an internal combustion engine operating using C1 to C2. 10 The fuel is a mixture of hydrocarbons or two or more thereof, more preferably a gas containing C1 to C8 hydrocarbons or two or more thereof, more preferably a mixture of C1 to C6 hydrocarbons or two or more thereof, more preferably a mixture of C1 to C5 hydrocarbons or two or more thereof, more preferably a gas containing methane and / or propane, and even more preferably a gas containing methane.

[0058] Preferably, one or more exhaust gases in the gas stream provided in step (1) have not been subjected to prior treatment for reducing N2O and / or NO emissions. x The catalytic treatment process, wherein preferably one or more exhaust gases have not previously undergone a catalytic treatment process for reducing emissions of one or more nitrogen oxides, and more preferably one or more exhaust gases have not previously undergone a catalytic treatment process for reducing emissions of N2O and / or NO. x The treatment process, and even more preferably, one or more exhaust gases have not previously undergone treatment processes for reducing one or more nitrogen oxides.

[0059] Preferably, in step (2), the contact between the airflow and the zeolite material containing the transition metal is carried out at a temperature ranging from 250°C to 550°C, preferably from 300°C to 500°C, more preferably from 325°C to 450°C, more preferably from 350°C to 425°C, more preferably from 380°C to 420°C, and even more preferably from 390°C to 410°C.

[0060] In a preferred step (2), the contact between the airflow and the zeolite material containing the transition metal is carried out at a pressure ranging from 1 to 50 bar, preferably 2 to 30 bar, more preferably 3 to 25 bar, more preferably 4 to 20 bar, more preferably 5 to 15 bar, more preferably 6 to 10 bar, more preferably 7 to 9 bar, and even more preferably 7.5 to 8.5 bar.

[0061] Preferably, the process is a continuous process, and more preferably, in step (2), the gas stream is contacted with the transition metal-containing zeolite material for a period of 1,000 to 100,000 hours. -1 More preferably 2,500 to 50,000 h -1 More preferably 5,000 to 30,000 h -1 More preferably 10,000 to 25,000 h -1 And even more preferably 15,000 to 22,500 h -1 The air space velocity (GHSV) within the range is measured.

[0062] A method for treating nitrogen oxides and

[0063] Preferably containing NO according to the present invention x An apparatus for the flow of N2O and / or N2O, the apparatus comprising:

[0064] (i) A catalyst bed configured to contact a gas stream to be treated; wherein the catalyst bed comprises a transition metal-containing zeolite material having a BEA-type framework structure, the zeolite material being obtainable from an organic template-free synthetic process.

[0065] Preferably, the catalyst bed is a fixed-bed catalyst or a fluidized-bed catalyst, with a fixed-bed catalyst being more preferred.

[0066] The device preferably further includes:

[0067] (ii) One or more devices disposed upstream of a catalyst bed for injecting one or more reducing agents into a gas stream.

[0068] The one or more transition metals included in the zeolite material of the present invention are preferably selected from the group consisting of Co, Ni, Cu, Fe, Ag, Au, Pt, Pd, Rh and combinations of two or more thereof, more preferably from the group consisting of Co, Ni, Cu, Fe and combinations of two or more thereof, even more preferably from the group consisting of Co, Cu, Fe and combinations of two or more thereof, and even more preferably the zeolite material contains Cu and / or Fe, preferably Fe.

[0069] Preferably, one or more transition metals are included in the zeolite material as non-framework elements.

[0070] The preferred zeolite material has a BEA-type framework structure comprising YO2 and X2O3, where Y is a tetravalent element and X is a trivalent element.

[0071] Preferably, Y is selected from the group consisting of Si, Sn, Ti, Zr, Ge, and mixtures of two or more of them, and Y is preferably Si.

[0072] Preferably, X is selected from the group consisting of Al, B, In, Ga, and mixtures of two or more of them, and X is preferably Al.

[0073] The preferred range of the YO2:X2O3 molar ratio is 2 to 100, more preferably 4 to 70, more preferably 5 to 50, more preferably 6 to 30, more preferably 7 to 20, more preferably 8 to 15, more preferably 9 to 13, and even more preferably 10 to 11.

[0074] Preferably, the molar ratio of one or more transition metals to X₂O₃ in the BEA-type framework structure ranges from 0.005 to 10, more preferably from 0.01 to 5, more preferably from 0.05 to 2.5, more preferably from 0.1 to 1.5, more preferably from 0.25 to 1, and even more preferably from 0.3 to 0.7.

[0075] The X-ray diffraction pattern of a preferably BEA-type framework zeolite material includes at least the following reflections:

[0076]

[0077] 100% of this involves the intensity of the largest peak in the X-ray powder diffraction pattern.

[0078] Preferably, the zeolite material with a BEA-type framework structure includes β-zeolite.

[0079] Preferably, zeolite materials containing transition metals are included in the molded article.

[0080] The catalyst composition of this invention may comprise a zeolite having a silica to alumina ratio of at least about 10, and a pore structure interconnected in all three crystal dimensions by pores having an average kinetic pore diameter of at least about 7 angstroms, for example, about 7 to 8 angstroms, and one or both of iron and copper promoters present in the zeolite, for example, in an amount of about 0.1% to 30% by weight, preferably about 1% to 5% by weight, of the total weight of the promoter and the zeolite. In addition to β, the zeolite may also comprise one or more of USY, β, and ZSM-20. A refractory binder may be mixed with the zeolite. Iron-promoted β zeolite is preferred and has been commercially available for the removal of NO by selective catalytic reduction (e.g., from gas turbine exhaust). x .

[0081] The iron-promoted β-zeolite in this invention is already an effective catalyst for the selective reduction of nitrogen oxides (e.g., by reducing nitrogen oxides with ammonia).

[0082] Unfortunately, it has been found that NO reduction from gas turbine exhaust can be difficult under harsh hydrothermal conditions, such as temperatures exceeding 500°C. x Iron-promoted β-zeolite activity begins to decline. This decline is believed to be due to zeolite instability, such as through dealumination and subsequent reduction of the metal-containing catalytic sites within the zeolite. To maintain NO x The overall reduction activity can be improved using stable iron-promoted aluminosilicate zeolite catalysts with iron in the Fe(OH) form.

[0083] Preferably, the iron accelerator is present in an amount of 0.1 to 30% by weight, calculated on a metal basis and based on the total weight of the metal and zeolite.

[0084] Preferably, the iron is present in an amount of 0.5 to 2.5 weight percent based on the metal.

[0085] Preferably, the zeolite has a silica to alumina ratio of at least about 8 and a porous structure interconnected in all three crystal dimensions by pores having an average kinetic diameter of at least about 7 Å.

[0086] Stable iron-promoted aluminosilicate zeolites preferably contain iron-promoted β-zeolites.

[0087] Preferably, the β-zeolite has a Si / Al ratio of not more than 10.

[0088] Stable iron-promoted aluminosilicate zeolites are preferably found at 3680 ± 5 cm⁻¹. -1 It has an FT-IR absorption peak at that location.

[0089] Preferably, the zeolite has a silica to alumina molar ratio of at least about 8 and a pore structure interconnected in all three crystal dimensions by pores having an average kinetic pore diameter of at least about 7 Å.

[0090] The zeolite mentioned therein is β-zeolite.

[0091] Preferably, the iron accelerator is present in an amount of 0.1% to 30% by weight, calculated on a metal basis and based on the total weight of the metal and zeolite.

[0092] Preferably, the iron is present in an amount of 0.5 to 2.5% by weight.

[0093] In this invention, metal-promoted aluminosilicate zeolite with improved stability can be formed by pre-steaming the aluminosilicate zeolite at a temperature of 600°C-800°C for a period of 0.25 to 8 hours. This pre-steaming does not provide significant dealumination of the aluminosilicate zeolite. Subsequently, a metal is added to the pre-steamed zeolite.

[0094] The metal in question is iron.

[0095] Preferably, the metal is added in an amount of 0.1% to 30% by weight based on the total weight of the metal and the aluminosilicate zeolite.

[0096] Preferably, the metal is added in an amount of 0.5 to 2.5% by weight based on the total weight of the metal and zeolite.

[0097] Preferably, the metal is iron, which is present in an amount of 0.7 to 1.5 weight percent based on the total weight of iron and zeolite.

[0098] Preferably, the zeolite has a silica to alumina ratio of at least about 8 and a porous structure interconnected in all three crystal dimensions by pores having an average kinetic pore diameter of at least about 7 Å.

[0099] Stable aluminosilicate zeolites include β-zeolite.

[0100] Stable metal-promoted aluminosilicate zeolites can be prepared by contacting the aluminosilicate zeolite with a lanthanide salt via ion exchange and subsequently with the lanthanide salt, and by adding a metal promoter to the lanthanide-treated aluminosilicate zeolite via ion exchange.

[0101] Preferably, the lanthanide salt is a cerium salt.

[0102] The metal accelerator mentioned above is iron.

[0103] Preferably, the metal accelerator is added in an amount of 0.1% to 30% by weight based on the total weight of the metal and zeolite, calculated on a metal-by-metal basis.

[0104] Preferably, the iron is added in an amount of about 0.5 to 2.5% by weight.

[0105] The zeolite mentioned therein is β-zeolite.

[0106] The stable iron-promoted aluminosilicate zeolite catalyst of this invention has iron in the form of Fe(OH).

[0107] Preferably, the iron accelerator is present in an amount of 0.1 to 30% by weight, calculated on a metal basis and based on the total weight of the metal and zeolite.

[0108] Preferably, the iron is present in an amount of 0.5 to 4 weight percent of the metal, for example, 0.5 to 2.5 weight percent.

[0109] Preferably, the zeolite has a silica to alumina ratio of at least about 8 and a porous structure interconnected in all three crystal dimensions by pores having an average kinetic diameter of at least about 7 Å.

[0110] Stable iron-promoted aluminosilicate zeolites include iron-promoted β-zeolite.

[0111] The β-zeolite preferably has a Si / Al ratio of no more than 10.

[0112] The method for reducing nitrogen oxides with ammonia according to the present invention comprises:

[0113] A gaseous stream containing nitrogen oxides and ammonia is contacted with a catalyst composition at a temperature of about 250°C to 600°C. The catalyst composition comprises: (a) a zeolite having a silica to alumina ratio of at least about 10 and a pore structure interconnected in all three crystal dimensions by pores having an average kinetic pore diameter of at least about 7 angstroms; and (b) a promoter selected from the group consisting of iron and copper, in an amount of about 0.1% to 30% by weight, calculated on a metallic basis and based on the total weight of the metals and zeolite.

[0114] Preferably, the promoter is present in an amount of about 1% to 5% by weight of the total catalytic material, and preferably the promoter contains iron.

[0115] The zeolite selected is from the group consisting of β.

[0116] Preferably, the catalyst composition further comprises a refractory binder mixed with zeolite.

[0117] The temperature treatment in step d) can increase the mechanical strength and cohesion of the bulk material and also helps to remove plasticizers and / or organic binders and pore-forming materials. Therefore, due to the use of transition alumina precursor particles and optionally binders and / or plasticizers, as well as pore-forming materials and / or dopants in step a), the Fe-doped β-zeolite component in the porous catalyst bulk material precursor is converted to form the Fe-doped β-zeolite catalyst bulk material.

[0118] Therefore, in step a), Fe-doped β-zeolite particles are used.

[0119] In this respect, three-dimensional monolithic fabric is a one-piece structure made of at least two stacked fiber layers.

[0120] Step b) is preferably controlled by a control system dataset or CAD file as described below, and is preferably implemented on a computer system.

[0121] According to the present invention, Fe-doped β-zeolite particles have been found to be usable in robotic casting processes, wherein mechanically stable catalytically active Fe-doped β-zeolite structures are obtained without heat treatment at temperatures above 600°C, exhibiting low pressure drop, high packing density, and high compressive strength.

[0122] This invention allows for the synthesis of catalyst profiles based on transition alumina with high external surface area and high strength. The high external surface area is achieved by avoiding high-temperature processing and by producing small fibers with a diameter preferably less than 1.2 mm, which can be stacked into a 3D structure. This 3D structure can be continuous fibers or composed of stacked discontinuous fibers suitable for commercial applications.

[0123] This invention leads to higher conversion and selectivity levels in Fe-doped β-zeolite catalysts, resulting in better product yields. The low pressure drop also enables increased mass flow rates and, again, higher hourly throughput, resulting in even better product and space-time yields. It also allows for NO removal in the NH3-SCR process at lower reaction temperatures. x This reaction facilitates better process economics. Furthermore, it reduces catalyst aging due to the shorter diffusion path and residence time. If coke formation occurs during catalyst operation, it helps to burn off the carbon more quickly, for example, with hot air or steam, and this regeneration requires less time, which is beneficial to process economics. Additionally, a new reactor smaller than the current setup can be designed, thereby reducing investment costs while maintaining current output (process intensification). In the case of multi-tube reactors, faster loading and more reliable process operation are expected.

[0124] Preferably, in the method according to the invention, no temperature or heat treatment is performed at temperatures above 600°C, more preferably above 500°C. Process steps c) and d) are preferably performed at temperatures not exceeding 600°C. Most preferably, the temperature treatment is performed at temperatures in the range of 300°C to 600°C, more preferably 400°C to 500°C.

[0125] The drying in step c) is preferably carried out at a temperature in the range of -100°C to less than 500°C, more preferably 0°C to 300°C, and most preferably 20°C to 150°C.

[0126] Step d) is preferably carried out at a temperature in the range of 400°C to 500°C and for a duration of 5 to 120 minutes.

[0127] The method according to the invention produces a three-dimensional porous transition alumina catalyst monolith, wherein no additional catalytically active metal, metal oxide or metal compound is applied to the surface of the Fe-doped β-zeolite particles, and the catalyst monolith is preferably not present in the suspension paste.

[0128] If intended, a small amount of dopant or mixture of dopant (e.g., compounds selected from Li, Na, K, Ca, Mg, Ba, B, Ga, Si, Ti, Zr, Fe, W, P, or Zn) may be present in the suspension paste in a maximum amount of 10 wt% based on the amount of Fe-doped β-zeolite particles or mixtures thereof (e.g., 0.1 to 10 wt%, preferably 1.0 to 5.0 wt% based on Fe-doped β-zeolite particles). Preferably, no dopant is used or the dopant is added to the suspension.

[0129] The final Fe-doped β-zeolite may also—unintentionally!—contain small amounts of impurities that can act as dopants. In such cases, typical impurities are Li₂O, Na₂O, K₂O, CaO, MgO, BaO, B₂O₃, Ga₂O₃, SiO₂, TiO₂, ZrO₂, ZnO, Fe₂O₃, as well as chlorides, nitrates, and sulfates. If doping is not intended (which is preferred), these amounts should be as low as possible. Typically, for such cases, in Fe-doped β-zeolite, the amount of such impurities is based on no more than 5% Fe-doped β-zeolite in the bulk, more preferably no more than 2.5%, and particularly no more than 0.5 wt%. In preferred specific embodiments, the impurity content will be less than 0.1 wt%, for example in the case of ultrapure or high-purity Fe-doped β-zeolite materials, and no dopant is used or added to the suspension.

[0130] Therefore, apart from Fe, the catalyst pack preferably does not contain any additional catalytically active components (such as catalytically active metals) in the final catalyst pack.

[0131] β-zeolite can be prepared as described in the above patent documents.

[0132] The BET surface area in the bulk catalyst, as determined by single-point adsorption using the BET equation (as described, for example, by G. Sandstede et al., Chem. Ing. Tech. [Chemical Engineering and Technology] 32 (1960), 413), should be at least 10 m² / g.

[0133] The final catalyst bulk preferably has a surface area in the range of 10 to 1000 m² / g, more preferably 25 to 800 m² / g, most preferably 50 to 800 m² / g, for example 50 to 350 m² / g. The surface area is preferably determined by the single-point BET method.

[0134] Pore ​​volume is another important requirement, and it is therefore important that the total pore volume, as determined by mercury porosimetry or nitrogen physisorption, is sufficiently high. In absolute terms, the total pore volume should be at least 0.05 ml / g.

[0135] In specific embodiments, it may be desirable for the pore volume in pores exceeding 50 nm, more preferably exceeding 250 nm, and most preferably exceeding 500 nm to form the majority of the total pore volume.

[0136] In specific embodiments, the ratio of pore volume in pores larger than 50 nm to the total pore volume should preferably be greater than 3%. Fe-doped β-zeolites with these characteristics exhibit good reactant accessibility, making them well-suited for catalytic reactions requiring good diffusion of reactants and products through the Fe-doped β-zeolite catalyst, thereby minimizing diffusion limitations.

[0137] Pore ​​volume and pore size distribution were determined using the Washburn equation via mercury porosimetry, as described by J. Rouquerol et al. in Pure & Applied Chem., 66(8), 1994, pp. 1752-1753. Nitrogen physisorption was described by F. Schüth et al. in Handbook of Porous Solids, Wiley, 2002.

[0138] The pore volume of the final catalyst stock is preferably in the range of 0.05 to 2.0, more preferably 0.1 to 1.5, and most preferably 0.2 to 1.2 ml / g.

[0139] The pore volume of pores larger than 50 nm is preferably in the range of 3% to 50%, more preferably 5% to 40%, and most preferably 10% to 35% of the total pore volume.

[0140] Pore ​​size distribution is another important requirement. In specific embodiments, it is preferable to obtain a transitional alumina catalyst with a multi-peak pore size distribution (e.g., a bi-peak pore size distribution).

[0141] According to this specification, a multi-peaked pore size distribution means a pore size distribution in which, when the incremental pore volume is plotted as a function of pore size, the resulting function exhibits a maximum (or mode) within a first pore size range and a maximum (or mode) within a second pore size range. Typically, the maximum (or mode) is the number that appears most frequently within a specific range of numbers. In terms of pore size distribution, the maximum (or mode) pore size is the pore size corresponding to the highest peak in a graph showing the pore size distribution within a specific pore size range or a subrange falling within this range. Therefore, according to this specification, a multi-peaked pore size distribution means that within the first pore size range, there should be at least one peak in a graph showing the pore size distribution, and within the second pore size range, there should also be at least one peak in a graph showing the pore size distribution. An example is one with EP 2 231 559. Figure 2The multi-peak pore size distribution of the two peaks shown in Figure 3. The pore size can be either the pore diameter or the pore radius.

[0142] Preferably, in the multi-peak pore size distribution, the pore size range includes a first pore size range and a second pore size range, and the pore size in the first pore size range is smaller than the pore size in the second pore size range.

[0143] Preferably, the first pore size range is a pore diameter range of 0.1 to 50 nm (micropores and mesopores), and the second pore size range is a pore diameter range greater than 50 nm, for example, greater than 50 nm to less than 1500 nm (macropores). Preferably, the maximum value (or mode) in the first pore size range is at a pore diameter of 5 to 50 nm, more preferably 10 to 30 nm. Furthermore, preferably, the maximum value (or mode) in the second pore size range is at a pore diameter of 50 to 1500 nm, more preferably 100 to 1250 nm.

[0144] Preferably, the pore diameters corresponding to the maximum value (or mode) in the first pore diameter range and the second pore diameter range are separated by at least 200 nm, more preferably at least 300 nm, and at most 1,500 nm, more preferably at most 1,000 nm.

[0145] The pore size distribution was determined using the well-known mercury porosity method with the Washburn equation, as described by J. Rouquerol et al. in Pure & Applied Chem., 66(8), 1994, pp. 1752-1753.

[0146] Preferably, the catalyst to be used in this invention has a total pore volume of 3% to 50%, more preferably 5% to 40%, and most preferably 10% to 30% in pores with a diameter greater than 50 nm (macros). Furthermore, preferably, the catalyst has a total pore volume of 50% to 97%, more preferably 60% to 95%, and most preferably 70% to 90% in pores with a diameter of 0.1 to 50 nm (micropores and mesopores). Even further, preferably, the catalyst has a total pore volume of less than 3%, more preferably less than 2%, and even more preferably less than 1% in pores with a diameter greater than 1500 nm. Most preferably, the catalyst has essentially no pore volume in pores with a diameter greater than 1500 nm.

[0147] As mentioned above, using monolithic extrusions is important in terms of pressure drop related to the accessibility of the inner surface of transition alumina. This also plays a role in eliminating diffusion problems. Another advantageous characteristic of monolithic extrusions is the fact that the external surface area to volume ratio is more favorable than in the case of conventional molded parts used in catalysis.

[0148] An important aspect of the materials of this invention is their strength characteristics. As mentioned above, a lateral compressive strength of at least 10 N, preferably at least 20 N, more preferably at least 30 N, most preferably at least 50 N, and particularly at least 100 N, and a bulk crushing strength of at least 0.1 MPa are preferred. These parameters form the basis for the suitability of the bulk extrudates for use in large-scale reactors, such as in the chemical and petroleum industries. When bulk extrudates meet these requirements, they can be used in large fixed-bed reactors that require very strong catalysts. The lateral compressive strength and bulk crushing strength are defined as follows:

[0149] According to the present invention, the side compressive strength (SCS) of the catalyst bulk (preferably with dimensions of 1.5 cm x 1.5 cm x 1.2 cm (x, y, z axes, z being the stacking direction)) when pressing the planar side opposite to yz or xy is preferably at least 50 N, more preferably at least 60 N, more preferably at least 100 N, and most preferably at least 300 N.

[0150] The SCS of a molded body is defined as the pressure (in Newtons) at which the molded body is crushed when it is processed under pressure.

[0151] For example, the determination of SCS is disclosed in Oil & Gas Science and Technology – Rev. IFP, Volume 55 (2000), Issue 1, pp. 67–85, particularly Section 3.1.1. An example of determining SCS, including the resistance of a catalyst molded body to compressive forces, is as follows: the molded body is subjected to a compressive load between jaws. The force required to crush the molded body is measured and recorded in Newtons. This operation is performed using a semi-automatic Schleuniger Model 6D hardness tester. When testing the molded body, the YZ or XZ plane is upright between the measuring jaws. The “Start” button on the Schleuniger 6D is pressed. The jaws will slowly approach each other to perform the crushing test. The compressive strength is displayed on the Schleuniger and the computer monitor.

[0152] The maximum SCS depends on the material used to prepare the catalyst substrate, and also on the three-dimensional structure of the catalyst substrate and the fiber diameter. The more contact points between individual fiber layers, the higher the lateral compressive strength. Preferably, adjacent layers have at least 10 contact points with a neighboring layer, more preferably at least 20 contact points, and most preferably at least 30 contact points. Therefore, for a fiber layer with two neighboring layers, the number of contact points is twice the aforementioned number. Due to the contact points, the stack of fiber layers is self-supporting.

[0153] There is no upper limit to the SCS of the catalyst feedstock. Typically, the maximum SCS is 100,000 N, and often it is 10,000 N. Therefore, the SCS of the catalyst feedstock according to the invention is preferably in the range of 60 to 100,000 N, more preferably 100 to 100,000 N, and most preferably 300 to 100,000 N.

[0154] The maximum value can also be the maximum value that the machine used to measure SCS can measure. The maximum value can depend on the size of the whole piece. If the whole piece is larger than the machine allowed to measure it, the whole piece is cut into a suitable size, preferably 1.5 cm x 1.5 cm x 1.2 cm (xyz axis).

[0155] The packing crush strength (BCS) of the catalyst was defined as the pressure (in megapascals) required to form 0.5% fine powder (i.e., particles smaller than 0.425 mm) when processed under a piston in a tube. For this purpose, 17 ml of pre-screened catalyst prototyping on a 0.425 mm sieve was loaded into a cylindrical sample tube (27.3 mm in diameter), with 8 ml of steel balls loaded on top. The prototyping was then processed under varying (increased) pressures for three minutes, after which the fine powder was recovered and its percentage determined. This procedure was repeated until a level of 0.5 wt% fine powder was achieved.

[0156] Another aspect of material strength is abrasion, which is the amount of material that may be shed from the extrudate during use. This abrasion, as determined by ASTM D4058-87, should preferably be less than 10 wt%, more preferably less than 7.5 wt%, and particularly less than 5 wt%.

[0157] Fe-doped β-zeolite extrudates with the above properties can be prepared by mixing Fe-doped β-zeolite particles in the presence of a liquid (usually water) or an aqueous solution of an inorganic acid solvent (such as hydrochloric acid, sulfuric acid, nitric acid, acetic acid, or formic acid), adding a binder and / or a suitable plasticizer pore-forming material to form a paste, and then extruding the paste in the desired form using a suitable die.

[0158] Different types of binder materials can be used, such as those based on silica or clay or mixtures thereof. Binders can also be selected from organic materials. Although mixed oxides may form during calcination, this does not affect the main characteristics or composition of the whole material due to the low amount of binder.

[0159] Suitable hydroxide precursors for use as binders include gibbsite, calcite, gibbsite and doalite.

[0160] Suitable hydroxyl oxide precursors for use as binders include boehmite, boehmite, pseudoboehmite, and hexagonal gibbsite or tohdite.

[0161] Although common transition alumina is often derived from hydroxide or hydroxyl oxide precursors obtained from the Bayer process and has been found to have many catalytic applications, high-purity precursor materials (such as boehmite from the Ziegler process for the production of straight-chain alcohols) are sometimes preferred.

[0162] To synthesize Fe-doped β-zeolite catalysts, mixtures of different hydroxide precursors, mixtures of different hydroxyl oxide precursors, or mixtures of hydroxide and hydroxyl oxide precursors can also be used as binders.

[0163] To modify the surface properties, acidity, and basicity (“doping”) of Fe-doped β-zeolite catalysts, other elemental precursors may be intentionally included in the range of 0.1 wt% to 10.0 wt% based on their content in the final Fe-doped β-zeolite.

[0164] Suitable binders are alumina hydrates, such as boehmite (AlOOH) or galvanite (Al(OH)3), which can act as a pural binder. ® SB was obtained from Sasol.

[0165] The amount of binder material in the suspension paste is based on the amount of Fe-doped β-zeolite particles in the suspension paste not exceeding 50 wt%, preferably 0.1 to 50 wt%, more preferably 30 wt%, even more preferably 0.1 to 20 wt%, for example preferably 0.1 to 15 wt%, more preferably 1 to 10 wt%, and most preferably in the range of 2.5% to 5%.

[0166] In addition, organic plasticizers may be needed to obtain a homogeneous mixture and to convert the mixture into a compound with rheological behavior. Plasticizers can be selected from organic materials, such as waxes. It is preferable to use plasticizers that are removed during calcination, while providing and maintaining the required strength. The amount of plasticizer used in the preparation of the paste to be extruded will vary depending on the type of material and the desired properties. Typically, based on the amount of Fe-doped β-zeolite particles, it will not exceed 10 wt%, preferably not more than 1.5 wt%, and more preferably not more than 2.5 wt%. Preferred plasticizers are polyepoxides, more preferably polyethylene oxides, which can be obtained as Alkox E-160 from Meisei Chemical Works, Ltd.

[0167] Preferably, if applied to a mixture, the amount of plasticizer will not exceed 10 wt% based on the total weight of the suspension paste.

[0168] The pore-forming material is preferably a cellulose material, more preferably a cellulose ether, and most preferably selected from hydroxyethyl methylcellulose (HEMC), methylcellulose (MC), hydroxypropyl methylcellulose (HPMC), or mixtures thereof. The amount of pore-forming material is based on the amount of Fe-doped β-zeolite particles in the suspension paste, not exceeding 30 wt%, preferably from 0.1 to 20 wt%, more preferably from 0.5 to 10 wt%, and most preferably from 1 to 6 wt%.

[0169] The colloidal solvent is preferably an inorganic acid, more preferably nitric acid. The amount of colloidal solvent in the suspension paste is based on the amount of Fe-doped β-zeolite particles in the suspension paste not exceeding 7 wt%, preferably from 0.05 to 5 wt%, more preferably from 0.1 to 3 wt%, and most preferably from 0.2 to 1 wt%.

[0170] In the method according to the invention, the suspension paste in step a) contains no fiber or only a very small amount of fiber. The fiber is selected from organic and inorganic fibers and may be present in a total amount of 0 to 3 wt%, preferably 0 to 0.9 wt%, more preferably 0 to 0.45 wt%, and most preferably 0% based on the suspension paste. The fiber is an elongated solid with a length at least 4 times, more preferably at least 8 times, and most preferably at least 15 times the (maximum) diameter. For fibers with a non-circular cross-section, the maximum cross-sectional diameter is considered here. Therefore, this paste differs from the pastes described in US 2007 / 0259770 and US 2009 / 0291824.

[0171] The final suspension paste preferably has a suitable viscosity for extrusion through a nozzle as described below.

[0172] For Fe-doped β-zeolite catalysts, the preferred number-average particle size in step a) is in the range of 0.05 to 700 µm, more preferably 0.5 to 500 µm, and more preferably 1 to 250 µm.

[0173] In this regard, average particle size can be measured by sieving particles, laser diffraction, or photographic techniques such as camsizers. Average particle size is either exponential average or arithmetic average. For irregular particle shapes, the number-mean maximum particle size is measured.

[0174] The suspension paste prepared in step a) of the process according to the invention preferably has a solid content of 1 to 95 wt%, more preferably 10 to 65 wt%.

[0175] The 3D robotic casting technology used in this invention has been well established and can be performed as described in US 7,527,671, US 6,027,326, US 6,401,795, WO 2019 / 229040, Catalysis Today 273 (2016), pp. 234-243, or Journal of Catalysis 334 (2016), pp. 110-115, or US 6,993,406.

[0176] 3D robotic casting technology can be used with catalyst formulations that are based on pastes currently used in standard extrusion technologies, provided the particle size is small enough to pass through the extrusion nozzle. The extrusion formulation or paste contains transition alumina particles, hydroxide precursor particles, or hydroxyl oxide precursor particles, or mixtures thereof. If desired, binders and / or plasticizers can be added to the extrusion mixture.

[0177] Robotic casting technology means extrusion through one or more nozzles, which preferably have a maximum diameter of less than 5 mm, more preferably less than 1 mm, and most preferably less than 0.8 mm. Specifically, the nozzle diameter should be in the range of 0.05 mm to 0.4 mm, and most preferably 0.2 mm to 0.4 mm. The nozzle can have any desired cross-section, such as circular, elliptical, square, star-shaped, or leaf-shaped. The maximum diameter is the maximum diameter of a non-circular cross-section.

[0178] One of the key criteria for robotic casting is the use of extrudable pastes with the correct rheological properties for robotic casting technology. The aforementioned literature provides detailed recommendations on how to obtain the desired rheological properties.

[0179] If desired, a viscosity modifier may be used in the process according to the invention. A typical viscosity modifier is cellulose, such as carboxymethyl cellulose. Preferably, no (additional) viscosity modifier is used.

[0180] The term "porous" as used herein defines a bulk material that is not a solid block but contains channels or pores. Through channels or pores can be formed by stacking spatially separated catalyst fiber layers in an ABA or ABACA (also known as ABC) configuration. Thus, pathways with or without direct line of sight can be formed.

[0181] The porosity is preferably at least 20%, more preferably at least 30%, and can preferably be in the range of 20% to 90%, and can be determined by nitrogen physical adsorption, Hg-PV, and He density. It can be determined by the following formula: Porosity (%) = 100 - [(total micro-extrusion structure density / fiber material density) x 100]. The total micro-extrusion structure density is determined by dividing its total weight by its total volume. The fiber material density can be determined by measuring the Hg-PV and He densities.

[0182] Because the lattice or scaffold formed by fibers is self-supporting, open spaces are maintained between the fibers, resulting in porosity. Corresponding structures can be seen in the aforementioned literature. When used in reactors, they exhibit low pressure drop.

[0183] The robotic casting process employed according to the present invention can also be described as 3D fiber deposition.

[0184] General description of 3DFD

[0185] 3D fiber deposition (3DFD) is used to shape powders. The 3DFD method is an adaptive manufacturing process in which a high-load paste is extruded through a moving nozzle. By computer-controlled movement of the extruder head in the x, y, and z directions, porous materials can be produced layer by layer from the extruded fibers or strands. After drying, the porous material can be heat-treated.

[0186] The main benefit of this technology is the freedom regarding porous parameters (fiber thickness, inter-fiber spacing, and stacking design).

[0187] A typical flowchart for 3DFD technology includes the following subsequent steps:

[0188] Prepare a high-viscosity paste

[0189] Extrusion through a thin nozzle

[0190] Computer-controlled fiber deposition to form porous periodic structures

[0191] Dry and reduce if necessary

[0192] The first important step is to ensure that there are no large particles in the paste. Therefore, the particle size of the starting material is checked. If there are particles that are too large, the powder is sieved to obtain the desired particle size. As a rule of thumb, the largest particles (indicated by the D 99 value) should preferably be at least five times smaller, more preferably at least ten times smaller than the nozzle size to be used.

[0193] In the next step, the powder is mixed with a solvent / diluent (e.g., water), and binders and additives such as plasticizers are added if necessary to obtain a viscous paste. Good mixing to achieve a homogeneous paste (minimizing agglomerates or incorporated air bubbles) is a prerequisite for a smooth and reproducible process. The powder loading of the functional material depends on the specific surface area, particle size distribution, and powder morphology. Generally, as the particle size of the powder decreases, the viscosity of the paste increases. Therefore, it is necessary to reduce the solids loading of these powders. In addition to one or more organic or preferably inorganic binders, plasticizers can be added to control the rheological behavior of the paste. In some cases, defoamers are also added to avoid air bubbles in the paste.

[0194] After mixing and degassing, the paste is transferred to a paste reservoir and installed on a 3DFD setup. A nozzle, preferably plastic or metal (below 200 µm), is attached to the paste reservoir. Paste extrusion is achieved, for example, by a displacement pump or screw pump. Controlling drying conditions may be necessary during deposition.

[0195] After drying at room temperature (or under controlled atmosphere and temperature), the 3DFD structure is dried and heat-treated (if necessary). Heat treatment at temperatures above 1000°C is not required.

[0196] Experimental procedures for 3DFD process

[0197] Achieving a smooth process and tight control over the extrusion of thin filaments typically requires adjusting both the paste formulation and experimental setup. The key process parameters that must be addressed are listed below.

[0198] parameter

[0199] Particle size distribution of starting materials

[0200] Paste preparation and mixing procedures

[0201] Paste formulation

[0202] Degassing and paste storage filling

[0203] Design of deposition platform

[0204] Nozzle height control

[0205] Programming of turns and transitions between layers

[0206] Adjust extrusion speed and moving speed

[0207] Drying conditions during deposition

[0208] For a further description of this process, please refer to the documents listed above.

[0209] The stacking design is preferably as described in US 7,527,671. Figure 1 and Figure 2 The preferred arrangement is a 1-3-1 pattern or a 3DFD structure 1-3 or 1-1, as shown in Figure 3 of Chemical Papers 68 (9), pp. 1143-1153 (2014), or (1.1) stacking or (1.3.5) stacking, as shown in Int. J. Appl. Ceram. Technol. 9 [5], pp. 902-910 (2012). Figure 1 As shown.

[0210] The liquid diluent used can be selected from water and organic liquid diluents. Preferably, the liquid diluent mainly contains water or water.

[0211] Drying is preferably carried out at a temperature in the range of -100°C to 500°C, more preferably 0°C to 300°C, and most preferably 20°C to 150°C.

[0212] No treatment of porous catalyst precursors or porous catalyst preparations is performed at temperatures above 600°C, preferably above 550°C, and more preferably above 500°C.

[0213] Stacked catalyst fiber monoliths are preferably three-dimensionally structured by depositing extruded fibers in a regular, repeating stacking pattern (periodic structured catalyst) to form a three-dimensionally structured porous catalyst monolith precursor.

[0214] The complete material can be formed from a single continuously extruded fiber or from multiple individually extruded fibers.

[0215] Preferably, the regular, repeating stacked pattern consists of stacked layers of extruded fibers, wherein in each layer at least 50 wt%, more preferably at least 90 wt%, of the extruded fibers or each type of fiber is deposited parallel to each other and spatially separated. The parallel deposition can be in a straight line or a curve. Alternatively, they can be deposited / stacked in a circular pattern with radial interlayers, such as a spider web pattern.

[0216] More preferably, at least 50 wt%, and most preferably at least 90 wt%, of the extruded fibers or each of the fibers is deposited as linear strands parallel to each other and spatially separated, wherein the direction of the strands in each layer is different from that in the adjacent layers, thereby creating a porous structure with contact points of adjacent stacked strands. Alternatively, multiple spider web patterns can be stacked, each pattern layer preferably rotated relative to its adjacent pattern layer.

[0217] US 7,527,671 Figure 1 and Figure 2The image depicts an example of layers stacked at 90° intervals in an alternating direction.

[0218] The fiber or strand preferably has a thickness of 10 to 5000 µm, more preferably 10 to 1000 µm, and most preferably 150 to 500 µm.

[0219] They are preferably spatially separated from each other by 10 to 5000 µm, more preferably by 100 to 1000 µm, and most preferably by 200 to 800 µm.

[0220] One example is a stack of 360 µm strands spaced 650 µm apart.

[0221] Typical bulk material dimensions are 1 mm³ and above, preferably 1 mm. 3 Up to 100 m 3 , more preferably 3 mm 3 Up to 300 m 3 .

[0222] The bulk material can have any desired shape. Preferably, it is in the form of a cylinder, cuboid, sphere, ellipse, tablet, or polygon with a circular or elliptical cross-section.

[0223] In contrast, typical extrusion processes for transition alumina catalyst extrudates produce extrudates with a minimum diameter of 1.2 mm. Depending on the formulation, these extrudates have strengths (lateral compressive strength) of less than 10 N or less than 100 N, as measured by the SCS method.

[0224] Structures made of 360 µm fibers and 650 µm fiber spacing and ABAB or ABC stacking exhibit lateral compressive strength greater than 100 N for 1.5 cm-1.5 cm-1.5 cm structures.

[0225] Therefore, the process according to the present invention produces a catalyst structure that combines high strength with high porosity, high geometric surface area, and high packing density.

[0226] The present invention also relates to a three-dimensional porous catalyst substrate of stacked catalyst fibers that can be obtained through the above process.

[0227] Furthermore, this invention relates to the use of these integral materials as catalysts in selective catalytic reduction reactions. Preferably, the reaction involves a gas phase, a liquid phase, or a mixture of liquid and gas phases. Reference can be made to the patent and non-patent documents discussed above.

[0228] Furthermore, the present invention relates to a control system dataset containing multiple control instructions that, when implemented in an additive manufacturing facility, instruct the additive manufacturing facility to produce the three-dimensional porous catalyst bulk or three-dimensional porous catalyst bulk precursor as described above.

[0229] Additive manufacturing facilities include, for example, 3D fiber deposition (3DFD), 3D printing, stereolithography, fused filament fabrication (FFF), or laser sintering. These facilities or equipment are used to shape powders or pastes to form three-dimensional monolithic catalysts or their precursors. Therefore, an additive manufacturing facility can be a 3D fiber deposition printer, a 3D printer, a stereolithography device, or a laser sintering device. These manufacturing facilities or equipment are typically computer-controlled using CAD files (computer-aided design files). CAD files contain information about the three-dimensional structure of the porous catalyst monolith or its precursors and are required for operating the additive manufacturing facility.

[0230] This CAD file, which can also be described as a control system dataset, contains multiple control instructions that drive an additive manufacturing facility (such as a moving nozzle in a 3D fiber deposition equipment). A control system dataset can also be described as a control system data log or data-driven set. A control system dataset or CAD file contains all the information required to drive the additive manufacturing facility to produce bulk material or bulk precursors. This meaning is covered by the term "hint" as used above. Control system datasets and control instructions are typically electronic data stored on a suitable data storage device, such as a computer's CD, DVD, USB stick, hard drive, or SSD drive, or attached to a computer.

[0231] Control system datasets are typically loaded into the computer controlling the additive manufacturing facility before the 3D structure is printed or extruded. Therefore, the term "implementation" generally refers to loading control system data or control commands into the computer system operating the additive manufacturing facility. Thus, the additive manufacturing facility implements the control commands thereon.

[0232] Compared to normal extrusions, the Fe-doped β-zeolite catalyst of the present invention exhibits lower pressure drop, higher activity, and higher selectivity in bulk. Because more of the catalyst's outer surface faces the reactants, more catalyst is immediately available. Therefore, the residence time of reactants in the catalyst can be shortened due to faster delivery. Consequently, fewer byproducts are formed.

[0233] Robotic casting processes allow for the fabrication of three-dimensional porous monolithic catalyst structures with stacked catalyst fibers, which, compared to normal extrusions, have an increased external surface area of ​​preferably at least 50 N, more preferably at least 60 N, and / or increased lateral compressive strength.

[0234] Furthermore, higher catalyst densities in the reactor can be achieved due to the well-ordered stacking of the fibers. A filling density of up to 70% is possible by using the regularly stacked catalyst fibers prepared according to the present invention.

[0235] Compared to single extrusions, the low pressure drop allows for operation with smaller fiber diameters.

[0236] The invention will be further illustrated by the following examples.

[0237] Examples of 3D micro-extrusion catalysts:

[0238] Fe-doped (templateless) β-zeolite (Fe-TF-β):

[0239] Nitric acid colloid; Pural SB (Al2O3 binder)

[0240] Avoid low pH levels (< 2.9) to prevent dealuminization and damage to the zeolite framework.

[0241] Final calcination temperature < 500°C

[0242] CoA

[0243] - BET ≥ 480 m2 / g

[0244] - 2.8-3.5 wt.% Fe; 34-36 wt.% Si and 6.8-7.2 wt.% Al SAR 9-11; Low Na (≤0.05 wt.% Na, as Na2O)

[0245] - XRD: Relative crystallinity ≥ 95% or 71%-73%

[0246] - LOI: ≤ 10 wt.%

[0247] Target particle sizes: d10 1-2 µm, d50 1-6 µm, d90 2-25 µm

[0248] Walocel ® MW 15000 GB Dow / DuPont

[0249] NaCl (0.5%-3%)

[0250] Hydroxyethyl methylcellulose (CAS: 9032-42-2) HEMC

[0251] Alkox E-160 Kowa Europe GmbH or Meisei Chemical Industry Co., Ltd.

[0252] EO homopolymer

[0253] High viscosity, MW approximately 4,000,000; 0.5 wt.% 100-200 mPa s (aqueous solution)

[0254] First extrudate:

[0255] Piston press; Pural from Sasol ® SB is used as a binder for soluble HNO3; zeolite content: 70, 75, and 80 wt.%.

[0256] Extrusion test

[0257] 3 mm extrusion

[0258] Walocel®, PEO, nitric acid, zeolite binder, water

[0259] Key parameter: HNO3 concentration Less than 1 wt.%, for stable extrusion using a 3.0 mm die, but with a trade-off between mechanical properties and pore volume (Hg-PV < 0.4 ml / g).

[0260] Formulation (total > 100 wt.% and excluding acid or water)

[0261] - Fe-TF-β 200 kg (70 wt.%)

[0262] - Pural SB ® 109 kg (30 wt.%)

[0263] - 58% nitric acid 1.6 kg (HNO3-free)

[0264] Alkox E-160 3.1 kg PEO (1 wt.%)

[0265] - Walocel MW15000 GB 9.3 kg (3 wt.%)

[0266] - 206 kg of water

[0267] Adding order

[0268] - MC + Fe-TF-β + Pural ® SB (dry blend)

[0269] - H2O (activation, mixing DAC)

[0270] - HNO3 solution (colloidal)

[0271] - Fe-TF-β (Solids content adjusted)

[0272] - "Aging" = overnight

[0273] 3D micro-extrusion porous Fe-doped β-zeolite catalyst monolithic material

[0274] The suspension is made from the above components, including Fe-doped β-zeolite particles, water, and acid (HNO3). The components are manually added and mixed to obtain the correct rheological properties for extrusion through a 400 µm nozzle. The particle size of the powder is selected to allow for this extrusion. The suspension is then fed into a dispensing unit consisting of a syringe container and a nozzle. This device is mounted on a micro-extruder. The micro-extruder is a computer numerical control (CNC) machine programmed to move according to a well-defined pattern and within a well-defined form. The CNC machine is programmed to continuously deposit filaments layer by layer in a predefined pattern. Deposition parameters, such as the distance between the nozzle and the surface of the structure, the nozzle movement speed, air pressure, and ambient temperature and airflow, are adjusted. A 3D structure is built in a cassette by depositing filaments layer by layer according to the programmed pattern and the desired size. All 3D structures are then dried at 80°C.

[0275] A) A temperature treatment of 450°C was applied to form a porous Fe-doped β-zeolite catalyst monolith. The dimensions of the monolith after temperature treatment were 1.91 cm x 1.90 cm x 0.74 cm (length, width, height). The porous characteristics of the monolith were found to be: BET surface area 184 m² / g, total pore volume 0.73 mL / g, and SCS > 720 N.

[0276] Go NO x experiment

[0277] NO removal from Fe-doped β-zeolite catalysts in 3D micro-extrusion x The test involved loading 25 cc of catalyst into a 1” OD (0.834” ID) x 4 ft stainless steel fixed-bed downflow reactor.

[0278] The reactor is equipped with a thermocouple sheath that houses five thermocouples.

[0279] The reactor is heated by passing it through a furnace, in which a catalyst is loaded so that it is located in the intermediate section of the furnace.

[0280] The catalyst mass loading is determined by multiplying the catalyst packing density by 25 cc.

[0281] In the case of a cylindrical [Example 1B], a monolithic structure was prepared as shown in Catalysis Today 216 (2013), page 21, Figure 4, where the 3DFD structure has a 1-3 stacked pattern. In each layer, five strands were deposited, each strand having a diameter of 1.5 mm. The spacing between two strands was also 1.5 mm. Compared to the image shown in Catalysis Today 216 (2013), page 21, Figure 4(a), a continuous strand was deposited in each layer in a zick-zack manner, thus providing linear parallel strands connected by their U-shaped connecting portions, resulting in one continuous strand per layer. The resulting cylindrical monolith had the following nominal dimensions: OD = 20.8 mm, height = 17.0 mm, and a nominal particle mass of approximately 3 g. The cylindrical monoliths were formed so that they could be stacked in a single row in the reactor.

[0282] To prepare these cylindrical materials, the nozzle size is adjusted accordingly.

[0283] In the case of the cylinders [Example 1C], the bulk density was determined based on the normal packing density of a cylindrical element with the following nominal dimensions: OD = 20.8 mm, ID = 5.56 mm, h = 16.74 mm, and a nominal particle mass of 2.814 g. These cylinders were formed such that they could be stacked in a single row in the reactor, with thermocouple sheaths protruding through a cut-out central hole.

[0284] In all cases, 1 / 8” Denstone spheres are used as bed carriers and in the preheating zone above the catalyst bed to provide surface area for feedstock evaporation.

[0285] Once loaded, the reactor is purged with 300 sccm N2 for about 30 minutes to remove air, and then heated to 400°C under flowing N2 and held for at least 4 hours.

[0286] Once catalyst pretreatment is complete, cool the reactor to 200°C and pressurize it to 14.5 psig. Once pressure and temperature stabilize, stop the N2 flow and introduce a feed consisting of 100 ppm N2O, 1000 ppm ammonia, and 8 wt.% water in an argon carrier gas at GHSV = 50,000 hr. -1 The rate at which GHSV is introduced into the reactor is defined as the volumetric flow rate of the gas / catalyst volume. The reactor is then maintained under these conditions at up to 500°C for approximately 24 hours.

[0287] Product analysis was performed using an online gas chromatograph equipped with a flame ionization detector (FID), a heated sample injection valve, and an HP-PLOT Q capillary column (30 m x 0.320 mm x 20 µm). The reaction effluent was delivered to the GC via a heated sample line at approximately 180°C–200°C, injected approximately every 15 min.

[0288] Calculate the following quantities and use them to evaluate and compare catalyst performance: N 20 and NO x Conversion rate percentage.

[0289] test

[0290] Test conditions:

[0291] Catalyst B

[0292] M_Kat = 14.5 g

[0293] GHSV = 50,000 hr -1

[0294] Total flow rate: 1816 l / h

[0295] Temperature: 250°C, 290°C, 310°C, 350°C, 410°C, 450°C, 500°C

[0296] Operation 1: 100 ppm N2O, 200 ppm NH3, and 10% O2 in argon carrier gas.

[0297] Operation 2: 100 ppm N2O, 1000 ppm NH3, 1000 ppm No, 10% O2, and 8% H2O in argon carrier gas.

[0298] Figure 1 The experiment demonstrates the operation of 1-N2O emission reduction in the presence of 100 ppm NH3 N2O + 200 ppm NH3.

[0299] In the presence of 200 ppm NH3, the N2O conversion curve shifts to a slightly lower temperature, but 350°C is still required to achieve a significant N2O conversion.

[0300] Figure 2The results show that running 2-SCR + N2O reduces emissions by 100 ppm N2O + 1000 ppm NH3 + 1000 ppm NO + 8 vol.% H2O.

[0301] In the presence of 100 ppm NO and NH3, up to 80% N2O conversion was achieved at 500°C for both fresh and HT-aged Fe BEA catalysts. No NO2 formation was observed at up to 500°C with a stoichiometric feed (NH3 / NO ratio = 1).

Claims

1. A method for producing a three-dimensional porous Fe-doped β-zeolite catalyst bulk material for stacked catalyst fibers, the method comprising the following steps: a) A suspension paste is prepared in a liquid aqueous diluent containing Fe-doped β-zeolite particles, wherein the suspension further comprises a binder material in a maximum amount of 50 wt% based on the amount of Fe-doped β-zeolite particles, a plasticizer and a pore-forming material each in a maximum amount of 10 wt% based on the amount of Fe-doped β-zeolite particles, and a solvent in a maximum amount of 5 wt% based on the amount of Fe-doped β-zeolite particles, wherein all particles in the suspension have a number-average particle size in the range of 0.05 to 700 µm. b) Extruding the paste from step a) through one or more nozzles to form fibers, and depositing the extruded fibers to form a three-dimensional porous catalyst monolithic precursor. c) Dry the porous catalyst precursor to remove the liquid diluent. d) The dried porous catalyst precursor from step c) is subjected to temperature treatment in the range of 300°C to 600°C to form the Fe-doped β-zeolite catalyst precursor. The porous catalyst precursor or porous catalyst substrate is not subjected to temperature treatment at a temperature above 600°C, and preferably, no other catalytically active metal, metal oxide or metal compound other than copper is applied to the surface of the Fe-doped β-zeolite particles, the catalyst precursor or Fe-doped β-zeolite catalyst substrate.

2. The method according to claim 1, wherein, The pore-forming material is a cellulose material, preferably a cellulose ether, more preferably selected from hydroxyethyl methylcellulose, methylcellulose, hydroxypropyl methylcellulose or mixtures thereof.

3. The method according to claim 1 or 2, wherein, This Fe-doped β-zeolite is obtained from a synthesis process without an organic template.

4. The method according to any one of claims 1 to 3, wherein, In step b), these nozzles have a maximum diameter of less than 5 mm, preferably less than 1 mm.

5. The method according to any one of claims 1 to 4, wherein, The stacked catalyst fiber monolith is three-dimensionally structured by depositing the extruded fibers in a regular, repeating stacking pattern to form a three-dimensionally structured porous catalyst monolith precursor. Preferably, the regular, repeating stacking pattern consists of stacked layers of extruded fibers, wherein at least 50 wt% of the extruded fibers in each layer are deposited parallel to each other and spatially separated, or deposited in a spider web pattern, and preferably the monolith is formed from a continuous extruded fiber or from multiple individual extruded fibers.

6. The method according to claim 5, wherein, At least 50 wt% of the extruded fiber is deposited as linear strands that are parallel to each other and spatially separated, or multiple spider web patterns are stacked therein, wherein the direction of the strands in each layer is different from that in the adjacent layers, thereby creating a porous structure with contact points of the strands in the adjacent layers.

7. The method according to any one of claims 1 to 6, wherein, The plasticizer is an organic plasticizer, preferably a polyepoxide, more preferably a polyepoxide, and / or the adhesive solvent is an inorganic acid, preferably nitric acid.

8. The method according to any one of claims 1 to 7, wherein, The adhesive material used is selected from the group consisting of: inorganic adhesives, preferably hydrated alumina, clay, silica or mixtures thereof, more preferably boehmite, calcite or mixtures thereof.

9. The method according to any one of claims 1 to 8, wherein, The Fe-doped β-zeolite catalyst moiety has a BET surface area greater than 50 m² / g, and / or the Fe-doped β-zeolite catalyst moiety has a pore volume greater than 0.25 ml / g, and / or the Fe-doped β-zeolite catalyst moiety has a single-peak or multi-peak pore size distribution.

10. The method according to any one of claims 1 to 9, wherein, The suspension paste in step a) contains fibers selected from organic and inorganic fibers in an amount of 0 to 3 wt%, preferably 0 to 0.9 wt%, more preferably 0 to 0.45 wt%, and most preferably 0% based on the suspension paste, and / or wherein the suspension paste in step a) contains Fe-doped β-zeolite particles in an amount of 60 to 90 wt%, preferably 65 to 85 wt%, and more preferably 70 to 80 wt% based on the suspension paste.

11. A three-dimensional porous catalyst monolith of stacked catalyst fibers, which can be obtained by the method according to any one of claims 1 to 10.

12. The three-dimensional porous Fe-doped β-zeolite catalyst bulk material of stacked catalyst fibers according to claim 11 in NO x Its applications in selective catalytic reduction reactions.

13. The use according to claim 12, wherein, This reaction results in N2O emission reduction.

14. The use according to claim 12 or 13, wherein, The reduction takes place in the presence of ammonia.

Images