Water-resistant manganese-based ultralow-temperature particle denitration catalyst based on hydrophobic flaky base material and preparation method of water-resistant manganese-based ultralow-temperature particle denitration catalyst

Abstract

The invention discloses a water-resistant manganese-based ultralow-temperature particle denitration catalyst based on a hydrophobic flaky base material and a preparation method thereof.The preparation method comprises the steps that a hydrophobic agent and manganese-based catalyst powder are subjected to ball-milling mixing, drying and grinding treatment, and hydrophobic composite powder is obtained; extruding the prepared hydrophobic composite powder into sheets through an internal mixer and / or a high-temperature roller press to form a sheet-shaped catalyst base material; adding a forming aid into the prepared flaky catalyst base material, and uniformly mixing by adopting mechanical stirring equipment; and carrying out extrusion tabletting molding on the prepared mixture through a high-pressure particle tabletting machine to prepare the water-resistant manganese-based ultralow-temperature particle denitration catalyst particles with sheet-shaped base material structural characteristics. According to the preparation method of the water-resistant manganese-based ultralow-temperature particle denitration catalyst based on the hydrophobic flaky base material, disclosed by the embodiment of the invention, the water-resistant manganese-based ultralow-temperature particle denitration catalyst prepared by the preparation method is relatively high in water resistance, relatively high in sulfur resistance and relatively high in mechanical strength.

Description

Technical Field

[0001] This invention relates to the field of flue gas denitrification catalytic materials technology, and in particular to a water-resistant manganese-based ultra-low temperature particulate denitrification catalyst based on a hydrophobic sheet substrate and its preparation method. Background Technology

[0002] Nitrogen oxides (NO) x Flue gas denitrification is one of the main sources of air pollution, and its emission control has become a key focus of environmental protection. Selective catalytic reduction (SCR) technology is currently the most widely used and technologically mature method for flue gas denitrification, but its techno-economic efficiency is highly dependent on catalyst performance.

[0003] In recent years, manganese-based catalysts have been widely recognized as the most promising alternatives to low-temperature SCR systems due to the abundant variable valence states, excellent low-temperature redox capabilities, and plentiful surface oxygen vacancies of manganese oxides. Existing research indicates that MnO x Manganese-based catalysts such as Mn-Ce and Mn-Sm can achieve NO reduction of over 90% in the low-temperature region. x Removal efficiency. However, manganese-based catalysts face three common bottlenecks when applied to industrial applications: poor water resistance, weak sulfur resistance, and low mechanical strength. In particular, in ultra-low temperature and high humidity flue gas (H2O content often reaches 8%–30%), water molecules compete strongly with NH3 and NO for adsorption at active sites, leading to a sharp drop in activity; SO2 not only reacts with active components to form thermally stable MnSO4, causing irreversible deactivation, but also reacts with NH3 to form ammonium bisulfate, covering the catalyst surface and blocking pores; the compressive strength of traditional powder or granular catalysts is generally lower than 40 N / particle, making them prone to breakage and pulverization under high-speed flue gas scouring, which makes it difficult to meet the requirements of long-term stable operation of industrial plants under ultra-low temperature and high humidity conditions.

[0004] Therefore, manganese-based catalysts in related technologies suffer from poor water resistance, weak sulfur resistance, and low mechanical strength, which need to be improved. Summary of the Invention

[0005] The present invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one objective of the present invention is to provide a method for preparing a water-resistant manganese-based ultra-low temperature particulate denitrification catalyst based on a hydrophobic sheet-like substrate. The water-resistant manganese-based ultra-low temperature particulate denitrification catalyst prepared by the method exhibits strong water resistance, strong sulfur resistance, and high mechanical strength.

[0006] The present invention also proposes a water-resistant manganese-based ultra-low temperature particulate denitrification catalyst based on a hydrophobic sheet substrate prepared by the above preparation method.

[0007] A method for preparing a hydrophobic manganese-based ultra-low temperature particulate denitration catalyst based on a hydrophobic sheet substrate according to a first aspect of the present invention is characterized by comprising: Step (1) Preparation of hydrophobic composite powder: The hydrophobic agent and manganese-based catalyst powder are ball-milled, dried and ground to obtain the hydrophobic composite powder; Step (2) Preparation of sheet catalyst substrate: The hydrophobic composite powder obtained in step (1) is extruded into sheets by a mixer and / or a high-temperature roller press to form the sheet catalyst substrate; Step (3) Preparation of the mixture: Add molding aid to the sheet catalyst substrate obtained in step (2) and mix evenly using a mechanical stirring device; Step (4) Preparation of water-resistant manganese-based ultra-low temperature particle denitration catalyst: The mixture obtained in step (3) is extruded and pressed into tablets by a high-pressure particle press to obtain the water-resistant manganese-based ultra-low temperature particle denitration catalyst particles with a sheet-like substrate structure.

[0008] According to the present invention, a method for preparing a hydrophobic manganese-based ultra-low temperature particulate denitrification catalyst based on a hydrophobic sheet substrate is described. This method involves bulk composite of a hydrophobic agent and manganese-based catalyst powder to construct a continuous three-dimensional hydrophobic network on and inside the catalyst surface. This achieves a leap from "surface hydrophobicity" to "overall hydrophobicity" in the manganese-based catalyst, improving the durability of the catalyst's water resistance, reducing the deposition of water-soluble sulfides such as sulfur dioxide on the catalyst surface, reducing the clogging of catalyst pores by ammonium bisulfate, and enhancing the catalyst's sulfur resistance. Furthermore, by first extruding the composite powder into sheet form... A two-step process, namely "first forming, then molding," is used to fabricate water-resistant manganese-based ultra-low temperature particulate denitrification catalyst particles with a sheet-like catalyst substrate. This process involves adding molding aids to multiple sheet-like catalyst substrates to form water-resistant manganese-based particulate denitrification catalyst particles with a sheet-like substrate structure. This process preserves the sheet-like substrate structure relatively intact inside the catalyst particles, forming a regular layered stacked pore system, which improves the hydrophobic and water-resistant capabilities of the catalyst and also enhances its mechanical strength. By adding molding aids and combining them with mechanochemical processes, a high-strength interfacial bond is achieved to the sheet-like substrate structure, enabling the compressive strength of a single catalyst particle to reach over 60 N, further enhancing the mechanical strength of the catalyst.

[0009] According to some embodiments of the present invention, the hydrophobic agent in step (1) includes at least one of fluorinated polymer, silane coupling agent, two-dimensional layered carbon material, graphite and carbon nanotubes; wherein the fluorinated polymer is polytetrafluoroethylene or polyvinylidene fluoride, the two-dimensional layered carbon material is graphene or graphene oxide; and the mass percentage of the hydrophobic agent in the hydrophobic composite powder is 2%–15%.

[0010] According to some embodiments of the present invention, the manganese-based catalyst powder in step (1) is obtained by roasting and pulverizing manganese cerium or manganese samarium as raw materials, and the mass ratio of the manganese-based catalyst powder in the hydrophobic composite powder is 85%–98%.

[0011] According to some embodiments of the present invention, in the grinding process described in step (1), a sand mill or a high-energy nano-grinding mill is used, the grinding medium is zirconia microspheres, and the particle size D50 of the resulting composite powder is 1-10 μm.

[0012] According to some embodiments of the present invention, in the extrusion process of step (2), the temperature is 25℃–450℃, the rotation speed is 50–100 rpm, and the pressure is 5–60 MPa. The hydrophobic composite powder is extruded into the sheet-like catalyst substrate with a thickness of 0.1–2 mm, a length of 5–20 mm, and a width of 5–20 mm by a mixer and / or a high-temperature roller press.

[0013] According to some embodiments of the present invention, the molding aid in step (3) includes glass fiber and / or clay, wherein the glass fiber includes at least one of chopped glass fiber, glass fiber powder and glass mat, and the clay includes at least one of bentonite, kaolin and montmorillonite.

[0014] According to some embodiments of the present invention, in step (3), the mass percentage of the molding aid in the mixture is 1%–10%; the minimum size of the sheet-like structure of the mixed material is not less than 2 mm.

[0015] According to some embodiments of the present invention, the mixing process described in step (3) is carried out in a ball mill under an inert atmosphere and is a mechanochemical composite treatment, wherein the ball milling speed is 300–500 rpm, the mass ratio of grinding balls to materials is (6–15):1, and the treatment time is 2–6 h.

[0016] According to some embodiments of the present invention, the tableting in step (4) is performed by extruding the mixture under a pressure of 10–200 MPa to obtain a water-resistant manganese-based ultra-low temperature particulate denitrification catalyst with a diameter of 5–9 mm, a length of 8–12 mm, and a compressive strength of not less than 60 N / particle.

[0017] According to a second aspect of the present invention, a water-resistant manganese-based ultra-low temperature particle denitration catalyst based on a hydrophobic sheet substrate is prepared by the preparation method described in the first aspect of the present invention.

[0018] According to embodiments of the present invention, a hydrophobic manganese-based ultra-low temperature particulate denitrification catalyst based on a hydrophobic sheet substrate is constructed by combining a hydrophobic agent with the bulk phase of the manganese-based catalyst powder, thereby building a continuous three-dimensional hydrophobic network on the surface and inside of the catalyst. This achieves a leap from "surface hydrophobicity" to "overall hydrophobicity" for the manganese-based catalyst, improving the durability of the catalyst's water resistance performance, reducing the deposition of water-soluble sulfides such as sulfur dioxide on the catalyst surface, reducing the clogging of catalyst pores by ammonium bisulfate, and enhancing the catalyst's sulfur resistance performance. Furthermore, by preserving the sheet substrate structure relatively intact inside the catalyst particles, a regular layered stacked pore system is formed, improving the catalyst's hydrophobic and water-resistant capabilities and enhancing its mechanical strength. By adding molding aids and combining with mechanochemical processes, a high-strength interfacial bond is achieved in the sheet substrate structure, enabling the compressive strength of a single catalyst particle to reach over 60 N, further enhancing the catalyst's mechanical strength.

[0019] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0020] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a method for preparing a water-resistant manganese-based ultra-low temperature particulate denitrification catalyst based on a hydrophobic sheet substrate according to some embodiments of the present invention; Figure 2 This is a schematic diagram of the denitrification efficiency of the water-resistant manganese-based ultra-low temperature particulate denitrification catalyst based on a hydrophobic sheet substrate according to Embodiment 1 of the present invention at different temperatures. Figure 3 This is a schematic diagram illustrating the denitrification efficiency of the water-resistant manganese-based ultra-low temperature particulate denitrification catalyst based on a hydrophobic sheet substrate under water vapor conditions with different moisture contents, according to Embodiment 1 of the present invention. Detailed Implementation

[0021] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0022] The following is for reference. Figure 1 This invention describes a method for preparing a water-resistant manganese-based ultra-low temperature particulate denitrification catalyst based on a hydrophobic sheet substrate according to an embodiment of the present invention.

[0023] refer to Figure 1The method for preparing a hydrophobic manganese-based ultra-low temperature particulate denitration catalyst based on a hydrophobic sheet substrate according to a first aspect of the present invention is characterized by comprising: Step (1) Preparation of hydrophobic composite powder: The hydrophobic agent and manganese-based catalyst powder are ball-milled, dried and ground to obtain hydrophobic composite powder; by obtaining hydrophobic composite powder, it is convenient to shape the catalyst in subsequent steps; Step (2) Preparation of sheet catalyst substrate: The hydrophobic composite powder obtained in step (1) is extruded into sheets by a mixer and / or a high-temperature roller press to form a sheet catalyst substrate; Step (3) Preparation of the mixture: Add molding aid to the sheet catalyst substrate obtained in step (2) and mix evenly using a mechanical stirring device; wherein, during the mixing process, the molding aid adheres to the surface of the sheet catalyst substrate; Step (4) Preparation of water-resistant manganese-based ultra-low temperature particle denitration catalyst: The mixture obtained in step (3) is extruded and pressed into tablets by a high-pressure particle press to obtain water-resistant manganese-based ultra-low temperature particle denitration catalyst particles with sheet-like substrate structure. The water-resistant manganese-based ultra-low temperature particle denitration catalyst particles are formed by stacking multiple sheet-like catalyst substrates in multiple directions.

[0024] By combining hydrophobic agents with manganese-based catalyst powder in bulk phase, a continuous three-dimensional hydrophobic network is constructed on the surface and inside of the catalyst, realizing the leap from "surface hydrophobicity" to "overall hydrophobicity" of the manganese-based catalyst. This improves the durability of the catalyst's water resistance performance, reduces the deposition of easily water-soluble sulfides such as sulfur dioxide on the catalyst surface, reduces the clogging of catalyst pores by ammonium bisulfate, and enhances the catalyst's sulfur resistance performance.

[0025] By first extruding composite powder into sheets to form sheet-like catalyst substrates, and then adding molding aids, multiple sheet-like catalyst substrates are used to prepare water-resistant manganese-based ultra-low temperature particulate denitrification catalyst particles with sheet-like substrate structures. This two-step process of "first forming sheets, then molding" preserves the sheet-like substrate structure relatively intact inside the catalyst particles, forming a regular layered stacked pore system, which improves the hydrophobic and water-resistant ability of the catalyst and also enhances the mechanical strength of the catalyst.

[0026] By adding molding aids and combining with mechanochemical processes, a high-strength interfacial bond is achieved in the sheet-like substrate structure, enabling the compressive strength of a single catalyst particle to reach over 60 N. Compared with the compressive strength of particle catalysts in related technologies, which is generally below 40 N / particle, this further enhances the mechanical strength of the catalyst.

[0027] Furthermore, the preparation process of this application embodiment is simple, the equipment is highly versatile, no complex and expensive special equipment is required, the raw materials are widely available, and it is easy to achieve large-scale industrial production. The catalyst prepared by the preparation method of this application embodiment can exhibit excellent comprehensive performance under complex flue gas conditions of ultra-low temperature, high humidity, sulfur and alkali metals, providing a practical and feasible technical solution for ultra-low temperature flue gas at the end of thermal power plants or ultra-low temperature flue gas in high water conditions in non-electric fields.

[0028] According to the present invention, a method for preparing a hydrophobic manganese-based ultra-low temperature particulate denitrification catalyst based on a hydrophobic sheet substrate is described. This method involves bulk composite of a hydrophobic agent and manganese-based catalyst powder to construct a continuous three-dimensional hydrophobic network on and inside the catalyst surface. This achieves a leap from "surface hydrophobicity" to "overall hydrophobicity" in the manganese-based catalyst, improving the durability of the catalyst's water resistance, reducing the deposition of water-soluble sulfides such as sulfur dioxide on the catalyst surface, reducing the clogging of catalyst pores by ammonium bisulfate, and enhancing the catalyst's sulfur resistance. Furthermore, by first extruding the composite powder into sheet form... A two-step process, namely "first forming, then molding," is used to fabricate water-resistant manganese-based ultra-low temperature particulate denitrification catalyst particles with a sheet-like catalyst substrate. This process involves adding molding aids to multiple sheet-like catalyst substrates to form water-resistant manganese-based particulate denitrification catalyst particles with a sheet-like substrate structure. This process preserves the sheet-like substrate structure relatively intact inside the catalyst particles, forming a regular layered stacked pore system, which improves the hydrophobic and water-resistant capabilities of the catalyst and also enhances its mechanical strength. By adding molding aids and combining them with mechanochemical processes, a high-strength interfacial bond is achieved to the sheet-like substrate structure, enabling the compressive strength of a single catalyst particle to reach over 60 N, further enhancing the mechanical strength of the catalyst.

[0029] According to some embodiments of the present invention, the hydrophobic agent in step (1) includes at least one of fluorinated polymer, silane coupling agent, two-dimensional layered carbon material, graphite and carbon nanotube; wherein, the fluorinated polymer is polytetrafluoroethylene or polyvinylidene fluoride, the two-dimensional layered carbon material is graphene or graphene oxide; the mass percentage of the hydrophobic agent in the hydrophobic composite powder is 2%–15%.

[0030] For example, the hydrophobic agent includes at least one of fluorinated polymers, silane coupling agents, two-dimensional layered carbon materials, graphite, and carbon nanotubes. It can be one of the hydrophobic agents including fluorinated polymers, silane coupling agents, two-dimensional layered carbon materials, graphite, and carbon nanotubes, or it can be multiple of the hydrophobic agents including fluorinated polymers, silane coupling agents, two-dimensional layered carbon materials, graphite, and carbon nanotubes.

[0031] For example, the mass percentage of the hydrophobic agent in the hydrophobic composite powder can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, etc. If the mass percentage of the hydrophobic agent in the hydrophobic composite powder is too high, it may result in low catalytic activity and low denitrification efficiency of the prepared catalyst; if the mass percentage of the hydrophobic agent in the hydrophobic composite powder is too low, the hydrophobic effect will be poor.

[0032] By making the hydrophobic agent account for 2%–15% of the mass of the hydrophobic composite powder, the water-resistant manganese-based ultra-low temperature particulate denitrification catalyst can have both good hydrophobic effect and high catalytic activity.

[0033] According to some embodiments of the present invention, the manganese-based catalyst powder in step (1) is obtained by roasting and pulverizing manganese cerium or manganese samarium as raw materials, and the mass ratio of manganese-based catalyst powder in hydrophobic composite powder is 85%–98%.

[0034] For example, the mass percentage of manganese-based catalyst powder in hydrophobic composite powder can be 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, etc. If the mass percentage of manganese-based catalyst powder in hydrophobic composite powder is too high, the hydrophobic effect may be poor; if the mass percentage of manganese-based catalyst powder in hydrophobic composite powder is too low, the denitrification efficiency of the prepared catalyst may be low.

[0035] By making the mass ratio of manganese-based catalyst powder in hydrophobic composite powder 85%–98%, the hydrophobic manganese-based ultra-low temperature particulate denitrification catalyst can have both good hydrophobic effect and high catalytic activity.

[0036] According to some embodiments of the present invention, in the grinding process of step (1), a sand mill or a high-energy nano-grinding mill is used, the grinding medium is zirconia microspheres, and the particle size D50 of the resulting composite powder is 1-10 μm.

[0037] For example, the particle size D50 of composite powder can be 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, etc.

[0038] By making the particle size D50 of the composite powder 1-10μm, it is beneficial to extrude the composite powder into sheets in subsequent steps, thereby forming a sheet-like catalyst substrate.

[0039] According to some embodiments of the present invention, in the extrusion of step (2), the temperature is 25℃–450℃, the rotation speed is 50–100rpm, and the pressure is 5–60MPa. The hydrophobic composite powder is extruded into a sheet catalyst substrate with a thickness of 0.1–2mm, a length of 5–20mm, and a width of 5–20mm by a mixer and / or a high-temperature roller press.

[0040] For example, in the extrusion of sheets in step (2), the extrusion temperature of the internal mixer and / or the high-temperature roller mill can be 25℃, 50℃, 100℃, 200℃, 300℃, 400℃, 450℃, etc.; the rotation speed of the internal mixer and / or the high-temperature roller mill can be 50rpm, 60rpm, 70rpm, 80rpm, 90rpm, 100rpm, etc.; and the extrusion pressure of the internal mixer and / or the high-temperature roller mill can be 5MPa, 10MPa, 20MPa, 30MPa, 40MPa, 50MPa, 60MPa, etc.

[0041] By extruding hydrophobic composite powder into sheet-like catalyst substrates with a thickness of 0.1–2 mm, a length of 5–20 mm, and a width of 5–20 mm, the thinness of the sheet-like substrate structure and its relatively regular two-dimensional planar structure facilitate the stacking of multi-layer sheet-like substrate structures during the extrusion molding process. By ensuring that the length and width of the sheet-like substrate structure are appropriate, it is easier to ensure that the sheet-like substrate structure is relatively intact during the subsequent uniform mixing process using mechanical stirring equipment. This helps to retain the sheet-like substrate structure relatively intact inside the catalyst particles, forming a regular layered stacked pore system, which improves the hydrophobic and water-resistant capabilities of the catalyst and also enhances the mechanical strength of the catalyst.

[0042] According to some embodiments of the present invention, the molding aid in step (3) includes glass fiber and / or clay, wherein the glass fiber includes at least one of chopped glass fiber, glass fiber powder and glass mat, and the clay includes at least one of bentonite, kaolin and montmorillonite.

[0043] For example, the molding aid in step (3) includes glass fiber and / or clay. It can be that the molding aid includes glass fiber, or it can be that the molding aid includes clay, or it can be that the molding aid includes both glass fiber and clay. The glass fiber includes at least one of chopped glass fiber, glass fiber powder, and glass mat. It can be that the glass fiber includes one of chopped glass fiber, glass fiber powder, and glass mat, or it can be that the glass fiber includes multiple of chopped glass fiber, glass fiber powder, and glass mat. The clay includes at least one of bentonite, kaolin, and montmorillonite. It can be that the clay includes one of bentonite, kaolin, and montmorillonite, or it can be that the clay includes multiple of bentonite, kaolin, and montmorillonite.

[0044] By including glass fiber and / or clay as the molding aid in step (3), a high-strength interfacial bond in the sheet substrate structure can be achieved, which is beneficial to enhancing the mechanical strength of the catalyst.

[0045] According to some embodiments of the present invention, in step (3), the mass percentage of the molding aid in the mixture is 1%–10%; the minimum size of the sheet structure of the mixed material is not less than 2 mm.

[0046] For example, the mass percentage of molding aids in the mixture can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc.; the minimum size of the sheet-like structure of the mixed material can be 2mm, 3mm, 4mm, 5mm, etc.

[0047] By ensuring that the minimum size of the sheet-like structure of the mixed material is not less than 2 mm, the sheet-like substrate structure can be relatively intact inside the catalyst particles, forming a regular sheet-like stacked pore system, which improves the hydrophobic and water-resistant ability of the catalyst and also enhances the mechanical strength of the catalyst.

[0048] According to some embodiments of the present invention, the mixing process in step (3) is carried out in a ball mill and under an inert atmosphere, wherein the ball milling speed is 300–500 rpm, the mass ratio of grinding balls to materials is (6–15):1, and the processing time is 2–6 h.

[0049] For example, the ball milling speed in the composite treatment process can be 300 rpm, 350 rpm, 400 rpm, 450 rpm, 500 rpm, etc.; the mass ratio of grinding balls to materials can be 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, etc.; and the composite treatment time can be 2h, 3h, 4h, 5h, 6h, etc.

[0050] By treating the flake catalyst substrate and the molding aid under the conditions of ball milling speed of 300–500 rpm, mass ratio of grinding balls to materials of (6–15):1, and processing time of 2–6 h, the flake substrate structure can be relatively intact inside the catalyst particles while the molding aid is uniformly attached to the surface of the flake catalyst substrate.

[0051] According to some embodiments of the present invention, the tableting in step (4) is performed by extruding the mixture under a pressure of 10–200 MPa to obtain a water-resistant manganese-based ultra-low temperature particulate denitrification catalyst with a diameter of 5–9 mm, a length of 8–12 mm, and a compressive strength of not less than 60 N / particle.

[0052] For example, the extrusion molding pressure can be 10MPa, 50MPa, 100MPa, 150MPa, 200MPa, etc.

[0053] For example, the diameter of the prepared water-resistant manganese-based ultra-low temperature particulate denitrification catalyst can be 5mm, 6mm, 7mm, 8mm, 9mm, etc., and the length can be 8mm, 9mm, 10mm, 11mm, 12mm, etc.

[0054] By preparing water-resistant manganese-based cryogenic particulate denitrification catalysts with diameters of 5–9 mm and lengths of 8–12 mm, the sheet-like substrate structure can form a regular layered stacked pore system within the denitrification catalyst particles, while also making the catalyst size convenient for use in the denitrification reaction.

[0055] The hydrophobic manganese-based ultra-low temperature particle denitration catalyst based on a hydrophobic sheet substrate according to the second aspect of the present invention is prepared by the preparation method according to the first aspect of the present invention.

[0056] For example, water-resistant manganese-based ultra-low temperature particulate denitrification catalysts based on hydrophobic sheet-like substrates are suitable for SCR denitrification reactions under ultra-low temperature and high humidity flue gas conditions.

[0057] By mixing hydrophobic agents with catalysts and giving the catalysts a unique sheet-like substrate structure, it is beneficial to improve the catalysts' ultra-low temperature water resistance, mechanical strength, and reaction mass transfer efficiency. This is especially suitable for working conditions where traditional manganese catalysts have insufficient ultra-low temperature activity and are easily poisoned and deactivated by water vapor.

[0058] According to embodiments of the present invention, a hydrophobic manganese-based ultra-low temperature particulate denitrification catalyst based on a hydrophobic sheet substrate is constructed by combining a hydrophobic agent with the bulk phase of the manganese-based catalyst powder, thereby building a continuous three-dimensional hydrophobic network on the surface and inside of the catalyst. This achieves a leap from "surface hydrophobicity" to "overall hydrophobicity" for the manganese-based catalyst, improving the durability of the catalyst's water resistance performance, reducing the deposition of water-soluble sulfides such as sulfur dioxide on the catalyst surface, reducing the clogging of catalyst pores by ammonium bisulfate, and enhancing the catalyst's sulfur resistance performance. Furthermore, by preserving the sheet substrate structure relatively intact inside the catalyst particles, a regular layered stacked pore system is formed, improving the catalyst's hydrophobic and water-resistant capabilities and enhancing its mechanical strength. By adding molding aids and combining with mechanochemical processes, a high-strength interfacial bond is achieved in the sheet substrate structure, enabling the compressive strength of a single catalyst particle to reach over 60 N, further enhancing the catalyst's mechanical strength.

[0059] The following is for reference. Figures 1-3 This invention describes a method for preparing a water-resistant manganese-based ultra-low temperature particulate denitrification catalyst based on a hydrophobic sheet substrate according to some embodiments of the present invention.

[0060] Example 1, refer to Figures 1-3 In this embodiment, the specific steps of the preparation method of the hydrophobic manganese-based ultra-low temperature particulate denitrification catalyst based on the hydrophobic sheet substrate are as follows: First, polytetrafluoroethylene (PTFE) as a hydrophobic agent is mixed with manganese cerium (Mn-Ce) catalyst powder at a mass ratio of 5:95, and then ball-milled in a ball mill for composite treatment. The ball milling speed is 400 rpm, the ball-to-material mass ratio is 10:1, and the treatment time is 4 hours. The composite material is dried at 105℃ for 12 hours, and then finely ground using a sand mill with zirconium oxide microspheres as the grinding media. The characteristic particle size D50 of the obtained composite powder is controlled to be 1-10 μm. Subsequently, the obtained hydrophobic composite powder is extruded into sheets using a mixer at a temperature of 250℃, a speed of 80 rpm, and a pressure of 30 MPa, to form sheets with a thickness of 0.5 mm, a length of 10 mm, and a width of 10 mm. The mixture is prepared by first obtaining a regular sheet-like material (mm in diameter); then adding 3% (by weight of the total mass of the sheet-like material and molding aid) of chopped glass fiber to the prepared sheet-like material, and performing a mechanochemical composite treatment in a ball mill under nitrogen as an inert atmosphere. The ball mill speed is 350 rpm, the ball-to-material mass ratio is 8:1, and the treatment time is 3 hours. The minimum size of the sheet-like structure in the mixed material is not less than 2 mm. Finally, the mixed material is directly extruded and pressed into tablets using a high-pressure particle press at a pressure of 50 MPa to obtain catalyst particles with a diameter of 8 mm and a length of 10 mm. The obtained catalyst particles are dried at 120℃ for 2 hours to obtain a water-resistant manganese-based ultra-low temperature particulate denitrification catalyst based on a hydrophobic sheet-like substrate. Figure 2 It can be seen that the catalyst has a denitrification efficiency greater than 95% above 130℃. Figure 3 It can be seen that the denitrification efficiency decreases by less than 6% under 20% water vapor conditions.

[0061] Example 2, refer to Figure 1In this embodiment, the difference between this embodiment and Embodiment 1 is that the hydrophobic agent adopts a composite hydrophobic system of graphene oxide and silane coupling agent. The specific steps of the preparation method of the water-resistant manganese-based ultra-low temperature particulate denitration catalyst based on the hydrophobic sheet substrate are as follows: First, graphene oxide and silane coupling agent are mixed at a mass ratio of 1:1 as a composite hydrophobic agent, and the total addition amount is 8% of the total mass of the hydrophobic agent and the manganese-based catalyst. The composite hydrophobic agent is mixed with manganese cerium catalyst powder, and ball milled for composite treatment. The ball milling speed is 450 rpm, the ball-to-material mass ratio is 12:1, and the treatment time is 5 hours. After drying, it is ground with a sand mill until the D50 is 1-10 μm. Then, the obtained hydrophobic composite powder is extruded into sheets by a high-temperature roller press. The extrusion temperature is 350℃, the speed is 60 rpm, and the pressure is 40 MPa. The sheets are extruded to a thickness of 0.3 mm, a length of 8 mm, and a width of 8 mm. The catalyst was prepared by first obtaining regular flake-shaped material (mm in diameter); then, 5% (by weight of the total mass of the flake material and molding aid) of bentonite was added to the obtained flake material, and the mixture was subjected to mechanochemical compounding treatment in a ball mill under inert atmosphere protection. The ball mill speed was 300 rpm, the ball-to-material mass ratio was 10:1, and the treatment time was 4 hours. Finally, the mixed material was directly extruded and compressed into tablets using a high-pressure granulator at a pressure of 100 MPa to obtain catalyst particles with a diameter of 6 mm and a length of 9 mm. The catalyst exhibits a denitrification efficiency greater than 92% above 130℃, and a denitrification efficiency decrease of less than 5% under 20% water vapor conditions.

[0062] Example 3, refer to Figure 1In this embodiment, the difference between this embodiment and Embodiment 1 is that the manganese-based catalyst powder uses a manganese samarium system. The specific steps of the preparation method of the water-resistant manganese-based ultra-low temperature particulate denitration catalyst based on a hydrophobic sheet substrate are as follows: First, polyvinylidene fluoride (PVDF) is mixed with manganese samarium catalyst powder at a mass ratio of 8:92 as a hydrophobic agent. The ball milling speed is 380 rpm, the ball-to-material mass ratio is 9:1, and the processing time is 5 hours. After drying, it is ground with a sand mill until the D50 is 1-10 μm. Then, the obtained hydrophobic composite powder is extruded into sheets through a mixer at a temperature of 280℃, a speed of 90 rpm, and a pressure of 50 MPa, to form sheets with a thickness of 1.0 mm, a length of 12 mm, and a width of 8 mm. The catalyst was first prepared into regular flake-shaped materials (mm in diameter). Then, a composite molding aid, consisting of chopped glass fiber and kaolin in a 1:2 mass ratio, was added to the prepared flake-shaped materials. This composite molding aid was then subjected to mechanochemical compounding in a ball mill at 320 rpm, a ball-to-material mass ratio of 9:1, and a treatment time of 3.5 hours. Finally, the mixed material was directly extruded and compressed into tablets using a high-pressure granulator at 120 MPa to obtain catalyst particles with a diameter of 9 mm and a length of 12 mm. The catalyst exhibited a denitrification efficiency greater than 94% above 130℃ and a denitrification efficiency decrease of less than 8% under 20% water vapor conditions.

[0063] Example 4, refer to Figure 1 In this embodiment, the difference from Embodiment 1 lies in adjusting the hydrophobic agent content and using graphite as an auxiliary hydrophobic component. The specific steps are as follows: First, polytetrafluoroethylene and graphite are mixed at a mass ratio of 4:1 to form a composite hydrophobic agent, with a total addition amount of 12% of the total mass of the hydrophobic agent and manganese-based catalyst. The composite hydrophobic agent is mixed with manganese-cerium catalyst powder, and the ball milling speed is 500 rpm, the ball-to-material mass ratio is 15:1, and the processing time is 6 hours. After drying, it is ground to a D50 of 1-10 μm. Subsequently, the obtained hydrophobic composite powder is extruded into sheets through a mixer at a temperature of 300℃, a speed of 70 rpm, and a pressure of 60 MPa, forming regular sheet materials with a thickness of 0.8 mm, a length of 15 mm, and a width of 10 mm. Then, montmorillonite (8% of the total mass of the sheet material and molding aid) is added to the obtained sheet material, and a mechanochemical composite treatment is performed in a ball mill at a speed of 400 rpm. The process involved pressing the mixture at 12:1 rpm for 5 hours, using a high-pressure pellet press to form catalyst particles with a diameter of 7 mm and a length of 10 mm. The final product was 180 MPa. The catalyst exhibited a denitrification efficiency greater than 95% at temperatures above 130℃ and a denitrification efficiency decrease of less than 5% under 20% water vapor conditions.

[0064] Comparative Example 1, This comparative example provides a manganese-cerium catalyst particle prepared by a conventional method without the addition of hydrophobic agents and molding aids. The specific steps are as follows: The manganese-cerium catalyst powder used in Example 1 was directly placed in a ball mill and hollow-milled for 4 hours without the addition of hydrophobic agents to serve as a control powder. The control powder was then dry-granulated with a small amount of water added as a binder. After granulation, the powder was extruded and cut into cylindrical particles with a diameter of 8 mm and a length of 10 mm. The resulting particles were dried at 120°C for 12 hours and calcined at 500°C for 4 hours to obtain conventional manganese-cerium catalyst particles. The catalyst exhibits a denitrification efficiency greater than 90% above 130°C, and a denitrification efficiency decrease of greater than 50% under 20% water vapor conditions.

[0065] Comparative Example 2, This comparative example provides manganese-based catalyst particles with a hydrophobic coating to contrast with the advantages of the overall hydrophobic structure of this invention. The specific steps are as follows: The manganese-cerium catalyst powder used in Example 1 was granulated by dry granulation, extrusion molding, and drying and calcining to obtain catalyst particles of the same specifications as in Comparative Example 1. A polytetrafluoroethylene (PTFE) emulsion was diluted to a solid content of 5%, and the catalyst particles were immersed in the emulsion, ultrasonically treated for 30 minutes, and then drained. The impregnated particles were dried at 120°C for 6 hours and calcined at 300°C for 2 hours to obtain catalyst particles with a PTFE hydrophobic coating. The catalyst exhibits a denitrification efficiency greater than 90% above 130°C, and a decrease in denitrification efficiency of approximately 40% under 20% water vapor conditions.

[0066] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0067] In the description of this invention, "first feature" and "second feature" may include one or more of the features.

[0068] In the description of this invention, "a plurality of" means two or more.

[0069] In the description of this invention, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or it may include the first and second features not being in direct contact but being in contact through another feature between them.

[0070] In the description of this invention, the terms "above," "over," and "on top" for the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicating that the first feature is at a higher horizontal level than the second feature.

[0071] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0072] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for preparing a water-resistant manganese-based ultra-low temperature particulate denitration catalyst based on a hydrophobic sheet-like substrate, characterized in that, include: Step (1) Preparation of hydrophobic composite powder: The hydrophobic agent and manganese-based catalyst powder are ball-milled, dried and ground to obtain the hydrophobic composite powder; Step (2) Preparation of sheet catalyst substrate: The hydrophobic composite powder obtained in step (1) is extruded into sheets by a mixer and / or a high-temperature roller press to form the sheet catalyst substrate; Step (3) Preparation of the mixture: Add molding aid to the sheet catalyst substrate obtained in step (2) and mix evenly using a mechanical stirring device; Step (4) Preparation of water-resistant manganese-based ultra-low temperature particle denitration catalyst: The mixture obtained in step (3) is extruded and pressed into tablets by a high-pressure particle press to obtain the water-resistant manganese-based ultra-low temperature particle denitration catalyst particles with a sheet-like substrate structure.

2. The preparation method according to claim 1, characterized in that, The hydrophobic agent in step (1) includes at least one of fluorinated polymer, silane coupling agent, two-dimensional layered carbon material, graphite and carbon nanotubes; wherein the fluorinated polymer is polytetrafluoroethylene or polyvinylidene fluoride, the two-dimensional layered carbon material is graphene or graphene oxide; and the hydrophobic agent accounts for 2%–15% of the mass of the hydrophobic composite powder.

3. The preparation method according to claim 1, characterized in that, The manganese-based catalyst powder in step (1) is obtained by roasting and pulverizing manganese cerium or manganese samarium as raw materials. The mass percentage of the manganese-based catalyst powder in the hydrophobic composite powder is 85%–98%.

4. The preparation method according to claim 1, characterized in that, In the grinding process described in step (1), a sand mill or a high-energy nano-grinding mill is used, the grinding medium is zirconia microspheres, and the resulting composite powder has a particle size D50 of 1-10 μm.

5. The preparation method according to claim 1, characterized in that, In the extrusion process described in step (2), the temperature is 25℃–450℃, the rotation speed is 50–100rpm, and the pressure is 5–60 MPa. The hydrophobic composite powder is extruded into the sheet-like catalyst substrate with a thickness of 0.1–2mm, a length of 5–20mm, and a width of 5–20mm by a mixer and / or a high-temperature roller press.

6. The preparation method according to claim 1, characterized in that, The molding aid in step (3) includes glass fiber and / or clay, wherein the glass fiber includes at least one of chopped glass fiber, glass fiber powder and glass mat, and the clay includes at least one of bentonite, kaolin and montmorillonite.

7. The preparation method according to claim 1, characterized in that, In step (3), the molding aid accounts for 1%–10% of the mass of the mixture; the minimum size of the sheet-like structure of the mixed material is not less than 2 mm.

8. The preparation method according to claim 1, characterized in that, The mixing process described in step (3) is carried out in a ball mill under an inert atmosphere and is a mechanochemical composite treatment. The ball mill speed is 300–500 rpm, the mass ratio of grinding balls to material is (6–15):1, and the treatment time is 2–6 h.

9. The preparation method according to claim 1, characterized in that, The tableting process described in step (4) involves extruding the mixture under a pressure of 10–200 MPa to obtain a water-resistant manganese-based ultra-low temperature particulate denitrification catalyst with a diameter of 5–9 mm, a length of 8–12 mm, and a compressive strength of not less than 60 N / particle.

10. A water-resistant manganese-based ultra-low temperature particulate denitrification catalyst based on a hydrophobic sheet-like substrate, characterized in that, The hydrophobic manganese-based ultra-low temperature particulate denitrification catalyst based on a hydrophobic sheet substrate is prepared by the preparation method according to any one of claims 1-9.

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