Honeycomb vanadium-based denitration catalyst and preparation method thereof

Abstract

The invention discloses a honeycomb vanadium-based denitration catalyst and a preparation method thereof, and belongs to the technical field of denitration catalysts. The catalyst is prepared from the following components in percentage by mass: 0.1%-4% of ammonium metavanadate, 2%-5% of ammonium tungstate, 3%-10% of nanoscale titanium powder, 3%-4.5% of a pore forming agent, 1%-2.5% of a binder and the balance of titanium dioxide, the particle size of the nanoscale titanium powder ranges from 50 nm to 100 nm. The nanoscale titanium powder is introduced, and the oxidation exothermic peak of the nanoscale titanium powder is controlled to be matched with the decomposition temperature of ammonium metavanadate in the calcining process, so that the mechanical strength (the axial compressive strength is greater than or equal to 5.0 MPa) is remarkably improved while the high aperture ratio (greater than or equal to 70%) and the thin-wall structure (0.3-0.8 mm) are maintained, and the problem that an existing catalyst is difficult to consider high aperture ratio, thin wall and high strength at the same time is solved.

Description

Technical Field

[0001] This invention belongs to the field of denitrification catalyst technology, specifically relating to a honeycomb vanadium-based denitrification catalyst and its preparation method. Background Technology

[0002] Selective catalytic reduction (SCR) technology is currently the most widely used and mature process for removing nitrogen oxides (NOx) from industrial flue gas. This technology uses ammonia (NH3) as a reducing agent, and under the action of a specific catalyst, selectively reduces NOx in flue gas to harmless nitrogen (N2). Commercial SCR denitrification catalysts often employ a honeycomb structure to increase the specific surface area, improve denitrification reaction efficiency, and suppress SO2 oxidation side reactions.

[0003] To reduce the energy consumption of SCR systems, catalysts are required to have low pressure drop, which is typically achieved by increasing the catalyst's porosity (e.g., 70%–80%) and reducing its wall thickness (e.g., 0.3–0.8 mm). However, while high porosity and ultra-thin walls increase specific surface area and reduce pressure drop, they also significantly weaken the catalyst's mechanical strength, making it prone to breakage during production, transportation, loading, and operation, thus shortening its service life. Traditional preparation processes use ammonium metavanadate, ammonium tungstate, and titanium dioxide as main raw materials, and construct the porous structure by adding a large amount of pore-forming agents. During calcination… During the process, the pore-forming agent rapidly decomposes, releasing a large amount of heat, leading to an increased temperature difference between the inside and outside of the preform and generating significant thermal stress. Furthermore, the reduction in wall thickness further decreases the preform's inherent strength, making it more prone to cracking under thermal stress, ultimately resulting in deterioration of the catalyst's mechanical properties. In existing technologies, when the porosity is >70%, the axial compressive strength of the catalyst is generally below 3.5 MPa.

[0004] Therefore, there is an inherent contradiction between high porosity and thin-walled structure and high strength and low pressure drop. How to achieve catalyst thinning and high porosity while ensuring that its mechanical strength is not severely compromised has become a key technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a honeycomb vanadium-based denitration catalyst and its preparation method, so as to solve the technical problem that existing catalysts are difficult to achieve thin-walled, high-porosity and good mechanical strength at the same time.

[0006] To achieve the above objectives, the present invention employs the following technical solution: The honeycomb vanadium-based denitrification catalyst disclosed in this invention is composed of the following components by mass percentage: 0.1%~4% ammonium metavanadate, 2%~5% ammonium tungstate, 3%~10% nano-sized titanium powder, 3%~4.5% pore-forming agent, 1%~2.5% binder, and the remainder is titanium dioxide; The nano-sized titanium powder has a particle size of 50~100nm, a specific surface area of ​​10~20m² / g, an oxygen content of ≤0.1%, and a mass ratio of 1:7.5~1:28.3 with titanium dioxide.

[0007] Furthermore, the pore-forming agent is at least one of graphite, graphene precursor, and nutshell powder; the particle size D50 of the pore-forming agent is 10~15μm, and D90≤25μm.

[0008] Furthermore, the binder is at least one of methylcellulose, hydroxypropyl methylcellulose, and carboxymethylcellulose.

[0009] This invention also discloses a method for preparing the above-mentioned honeycomb vanadium-based denitration catalyst, comprising the following steps: Ammonium metavanadate, ammonium tungstate, titanium dioxide, nano-sized titanium powder, pore-forming agent and binder are mixed according to the mass percentage to obtain dry-based powder; Water and lubricant are added to the dry-based powder and kneaded to obtain a plastic slurry; The plastic clay is extruded through a honeycomb mold to obtain a wet blank; The wet blank was sequentially dried and calcined to obtain the honeycomb vanadium-based denitrification catalyst; During the calcination process, the oxidation exothermic peak temperature of the nano-sized titanium powder is 480~530℃, the decomposition temperature range of ammonium metavanadate is 450~550℃, and the temperature difference between the two is ≤30℃.

[0010] Further, the amount of water added is 30% to 35% of the total mass of the dry powder; the amount of lubricant added is 0.5% to 1% of the total mass of the dry powder, and the lubricant is at least one of polyethylene glycol 400 (purity ≥99.0%), rapeseed oil (industrial grade), glycerin (purity ≥99.0%), and stearic acid (industrial grade).

[0011] Furthermore, the honeycomb mold has 18 to 90 holes and a wall thickness of 0.3 to 0.8 mm; the shape of the mold holes in the honeycomb mold is square, hexagonal, or triangular.

[0012] Furthermore, the calcination process is carried out in an air atmosphere at a temperature of 500-600°C and a holding time of 4-8 hours.

[0013] Furthermore, the heating rate of the calcination treatment is 1~5℃ / min.

[0014] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a honeycomb vanadium-based denitration catalyst. By introducing nano-sized titanium to partially replace titanium dioxide in the composition, and utilizing its in-situ oxidation effect during calcination, it matches the decomposition temperature of ammonium metavanadate and ammonium tungstate to form a dense and strong chemical bond and sintering, significantly enhancing the strength of the catalyst skeleton. This successfully solves the contradiction between high porosity, thin walls, and high strength. While maintaining high activity and low pressure drop, this invention significantly improves mechanical strength, has good process compatibility and large-scale production prospects, and solves the technical problem that existing catalysts cannot simultaneously achieve thin walls, high porosity, and good mechanical strength.

[0015] Furthermore, according to relevant experimental results, the honeycomb vanadium-based denitrification catalyst of the present invention has an open porosity of ≥70%, a wall thickness of 0.3-0.8 mm, an axial compressive strength of ≥5.0 MPa, an SO2 oxidation rate of ≤0.8%, and a denitrification efficiency of ≥92%, which is superior to the traditional formulation.

[0016] This invention also discloses a method for preparing the aforementioned honeycomb vanadium-based denitration catalyst. This method utilizes the temperature synergistic effect of the in-situ oxidation process of metallic titanium and the decomposition of the active component to simultaneously ensure high catalytic activity (denitration efficiency ≥92%) and low SO2 oxidation rate (≤0.8%) while strengthening the catalyst framework and significantly improving mechanical strength (axial compressive strength ≥5.0MPa). Based on extrusion molding, this method can be achieved simply by optimizing raw materials and heat treatment regimes, without requiring complex equipment modifications. It also possesses excellent process compatibility and product performance reproducibility, resolving the long-standing technical contradiction between high porosity, thin walls, and high strength. Detailed Implementation

[0017] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0018] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0019] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0020] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0021] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0022] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0023] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" represents weight percentage, "parts" represents parts by weight, and "ratio" represents weight proportion.

[0024] Example 1 Step 1: Take 4% ammonium metavanadate (purity ≥99.0%), 4% ammonium tungstate (purity ≥99.0%), and 75% anatase titanium dioxide (specific surface area 180m²) by mass percentage. 2 / g, content ≥98%), 10% nano-sized titanium powder (particle size 80nm, specific surface area 15m²). 2 / g, oxygen content 0.08%), pore-forming agent 4.5% (graphite, D50 12μm, D90 20μm), binder 2.5% (hydroxypropyl methylcellulose, viscosity 10000mPa) Add the s) to a mixer and mix at 400 r / min for 1.5 h to obtain a uniform dry powder; Step 2: Add 30% water and 1% lubricant (polyethylene glycol 400) by weight of the dry powder to the dry powder and mix to form a plastic slurry; Step 3: Extrude the plastic clay through a square honeycomb mold with 90 holes, a wall thickness of 0.3 mm, to obtain a wet blank; Step 4: After drying the wet blank at 80℃ for 6 hours, it is heated to 500℃ in air at a rate of 2℃ / min and held at that temperature for 8 hours for calcination treatment. After cooling in the furnace, the honeycomb vanadium-based denitrification catalyst product is obtained.

[0025] Example 2 A method for preparing a honeycomb vanadium-based denitration catalyst includes the following steps: Step 1: Take ammonium metavanadate 0.1%, ammonium tungstate 5%, and anatase phase titanium dioxide 84.9% (specific surface area 160m²) according to the following mass percentages. 2 / g, content ≥99%), 3% nano-grade titanium powder (particle size 50nm, specific surface area 20m²). 2 / g, oxygen content 0.05%), pore-forming agent 4.5% (fruit shell powder, D50 10μm, D90 22μm), binder 2.5% (methylcellulose, viscosity 10000mPa) Add the s) to the mixer and mix at 500 r / min for 1 h to obtain a uniform dry powder; Step 2: Add 35% water and 0.5% lubricant (polyethylene glycol 400) by weight of the dry base powder to the dry base powder and mix to form a plastic slurry; Step 3: Extrude the plastic clay through a hexagonal honeycomb mold with 18 holes, a wall thickness of 0.8 mm, to obtain a wet blank; Step 4: After drying the wet blank at 80℃ for 6 hours, it is heated to 600℃ in air at a rate of 4℃ / min and held at that temperature for 4 hours for calcination treatment. After cooling in the furnace, the honeycomb vanadium-based denitrification catalyst product is obtained.

[0026] Example 3 A method for preparing a honeycomb vanadium-based denitration catalyst includes the following steps: Step 1: Take 1% ammonium metavanadate, 4% ammonium tungstate, and 85% anatase titanium dioxide (specific surface area 180m²) by mass percentage. 2 / g, content ≥98%), 4% nano-sized titanium powder (particle size 100nm, specific surface area 10m²). 2 / g, oxygen content 0.1%), pore-forming agent 3.5% (graphene precursor, D50 15μm, D90 25μm), binder 2.5% (carboxymethyl cellulose), add to a mixer and mix at 500r / min for 2h to obtain a uniform dry powder; Step 2: Add 32% water and 0.8% rapeseed oil by weight of the dry base powder to the dry base powder and mix to form a plastic mud. Step 3: Extrude the plastic clay through a honeycomb mold with 60 holes, a wall thickness of 0.45 mm, and triangular die holes to obtain a wet blank; Step 4: After the wet blank is dried at 60℃ for 10 hours, it is heated to 550℃ in air at 3℃ / min and held at that temperature for 6 hours for calcination treatment. After cooling in the furnace, the honeycomb vanadium-based denitrification catalyst product is obtained.

[0027] Example 4 A method for preparing a honeycomb vanadium-based denitration catalyst includes the following steps: Step 1: Take ammonium metavanadate 2%, ammonium tungstate 4%, and anatase phase titanium dioxide 84% (specific surface area 150m²) by mass percentage. 2 / g, content ≥98%), 5% nano-sized titanium powder (particle size 70nm, specific surface area 12m²). 2 / g, oxygen content 0.07%), pore-forming agent 4% (graphite: coconut shell powder = 1:1, D50 11μm, D90 21μm), binder 1% (hydroxypropyl methylcellulose), add to a mixer and mix at 700r / min for 1h to obtain a uniform dry powder; Step 2: Add 35% water and 0.9% rapeseed oil by weight of the dry base powder to the dry base powder and mix to form a plastic mud. Step 3: Extrude the plastic clay through a honeycomb mold with 50 holes, a wall thickness of 0.5 mm, and square die holes to obtain a wet blank; Step 4: After drying the wet blank at 60℃ for 10 hours, heat it to 520℃ in air at 3℃ / min and hold it for 7 hours for calcination treatment. After cooling in the furnace, the honeycomb vanadium-based denitrification catalyst product is obtained.

[0028] Example 5 A method for preparing a honeycomb vanadium-based denitration catalyst includes the following steps: Step 1: Take ammonium metavanadate 3.0%, ammonium tungstate 3%, and anatase phase titanium dioxide 83% (specific surface area 165m²) by mass percentage. 2 / g, content ≥98%), 6% nano-grade titanium powder (particle size 60nm, specific surface area 14m²). 2 / g, oxygen content 0.06%), pore-forming agent 3.5% (graphene precursor, D50 13μm, D90 23μm), binder 1.5% (methylcellulose), add to a mixer and mix at 400r / min for 2h to obtain a uniform dry powder; Step 2: Add 34% water and 1% stearic acid by weight of the dry powder to the dry powder and mix to form a plastic mud. Step 3: Extrude the plastic clay through a honeycomb mold with 70 holes, a wall thickness of 0.4 mm, and square die holes to obtain a wet blank; Step 4: After drying the wet blank at 60℃ for 8 hours, heat it to 580℃ in air at a rate of 4℃ / min and keep it at that temperature for 5 hours for calcination. After cooling in the furnace, the honeycomb vanadium-based denitrification catalyst product is obtained.

[0029] Example 6 A method for preparing a honeycomb vanadium-based denitration catalyst includes the following steps: Step 1: Take ammonium metavanadate 4%, ammonium tungstate 5%, and anatase phase titanium dioxide 80% (specific surface area 150m²) by mass percentage. 2 / g, content ≥98%), 7% nano-grade titanium powder (particle size 55nm, specific surface area 18m²). 2 The following ingredients were added to a mixer and mixed at 500 r / min for 2.5 h to obtain a uniform dry powder: 3% pore-forming agent (fruit shell powder, D50 14 μm, D90 24 μm) and 1% binder (carboxymethyl cellulose). Step 2: Add 31% water and 0.5% polyethylene glycol 400 by weight of the dry base powder to the dry base powder and mix to form a plastic mud. Step 3: Extrude the plastic clay through a honeycomb mold with 80 holes, a wall thickness of 0.35 mm, and hexagonal die holes to obtain a wet blank; Step 4: After the wet blank is dried at 60℃ for 8 hours, it is heated to 530℃ in air at a rate of 5℃ / min and held at that temperature for 7 hours for calcination treatment. After cooling in the furnace, the honeycomb vanadium-based denitrification catalyst product is obtained.

[0030] Example 7 A method for preparing a honeycomb vanadium-based denitration catalyst includes the following steps: Step 1: Take 3.5% ammonium metavanadate, 4.5% ammonium tungstate, and 79% anatase titanium dioxide (specific surface area 160m²) by mass percentage. 2 / g, content ≥98%), 8% nano-sized titanium powder (particle size 90nm, specific surface area 11m²). 2 The following ingredients were added to a mixer and mixed at 500 r / min for 2.5 h to obtain a uniform dry powder: 0.09% oxygen content, 3% pore-forming agent (graphite, D50 12μm, D90 20μm), and 2% binder (hydroxypropyl methylcellulose). Step 2: Add 35% water and 0.5% polyethylene glycol 400 by weight of the dry base powder to the dry base powder and mix to form a plastic mud. Step 3: Extrude the plastic clay through a honeycomb mold with 45 holes, a wall thickness of 0.55 mm, and triangular die holes to obtain a wet blank; Step 4: After drying the wet blank at 60℃ for 8 hours, heat it to 500℃ in air at 5℃ / min and keep it at that temperature for 8 hours for calcination treatment. After cooling in the furnace, the honeycomb vanadium-based denitrification catalyst product is obtained.

[0031] Example 8 A method for preparing a honeycomb vanadium-based denitration catalyst includes the following steps: Step 1: Take ammonium metavanadate 2.5%, ammonium tungstate 4%, and anatase phase titanium dioxide 80% (specific surface area 175m²) by mass percentage. 2 / g, content ≥98%), 9% nano-sized titanium powder (particle size 75nm, specific surface area 13m²). 2 / g, oxygen content 0.08%), pore-forming agent 3% (graphene precursor: graphite = 2:1, D50 13μm, D90 22μm), binder 1.5% (methylcellulose), add to a mixer and mix at 500r / min for 2.5h to obtain a uniform dry powder; Step 2: Add 33% water and 0.8% glycerin by weight of the dry base powder to the dry base powder and mix to form a plastic mud. Step 3: Extrude the plastic clay through a honeycomb mold with 35 holes, a wall thickness of 0.60 mm, and square die holes to obtain a wet blank; Step 4: After drying the wet blank at 60℃ for 8 hours, heat it to 550℃ in air at 5℃ / min and hold it for 4 hours for calcination treatment. After cooling in the furnace, the honeycomb vanadium-based denitrification catalyst product is obtained.

[0032] Example 9 A method for preparing a honeycomb vanadium-based denitration catalyst includes the following steps: Step 1: Take 1.5% ammonium metavanadate, 5% ammonium tungstate, and 80.5% anatase titanium dioxide (specific surface area 180m²) by mass percentage. 2 / g, content ≥98%), 9% nano-sized titanium powder (particle size 65nm, specific surface area 16m²). 2 / g, oxygen content 0.07%), pore-forming agent 3% (nut shell powder: graphite = 1:2, D50 10μm, D90 21μm), binder 1% (carboxymethyl cellulose), add to a mixer and mix at 500r / min for 2.5h to obtain a uniform dry-based powder; Step 2: Add 30% water and 0.6% glycerin by weight of the dry base powder to the dry base powder and mix to form a plastic mud. Step 3: Extrude the plastic clay through a honeycomb mold with 30 holes, a wall thickness of 0.65 mm, and triangular die holes to obtain a wet blank; Step 4: After the wet blank is dried at 60℃ for 8 hours, it is heated to 510℃ in air at a rate of 5℃ / min and held at that temperature for 7 hours for calcination treatment. After cooling in the furnace, the honeycomb vanadium-based denitrification catalyst product is obtained.

[0033] Example 10 A method for preparing a honeycomb vanadium-based denitration catalyst includes the following steps: Step 1: Take ammonium metavanadate 0.1%, ammonium tungstate 2%, and anatase phase titanium dioxide 83.9% (specific surface area 190m²) by mass percentage. 2 / g, content ≥98%), 10% nano-grade titanium powder (particle size 50nm, specific surface area 20m²). 2 The following ingredients were added to a mixer and mixed at 800 r / min for 1 h to obtain a uniform dry powder: 0.05% oxygen content, 3% pore-forming agent (graphene precursor, D50 15μm, D90 25μm), and 1% binder (hydroxypropyl methylcellulose). Step 2: Add 32% water and 0.9% stearic acid by weight of the dry powder to the dry powder and mix to form a plastic mud. Step 3: Extrude the plastic clay through a honeycomb mold with 25 holes, a wall thickness of 0.75 mm, and hexagonal die holes to obtain a wet blank; Step 4: After drying the wet blank at 60℃ for 8 hours, heat it to 590℃ in air at 5℃ / min and hold it at that temperature for 5 hours for calcination treatment. After cooling in the furnace, the honeycomb vanadium-based denitrification catalyst product is obtained.

[0034] Example 11 A method for preparing a honeycomb vanadium-based denitration catalyst includes the following steps: Step 1: Take 1% ammonium metavanadate, 2% ammonium tungstate, and 83% anatase titanium dioxide (specific surface area 170m²) by mass percentage. 2 / g, content ≥98%), 10% nano-grade titanium powder (particle size 85nm, specific surface area 12m²). 2 The following ingredients were added to a mixer at 300 r / min for 2 h: 1 g of hydroxypropyl methylcellulose and 0.08% oxygen content, 3% pore-forming agent (2% graphite, 1% graphene precursor, D50 12 μm, D90 20 μm), and 1% binder (hydroxypropyl methylcellulose: methylcellulose = 1:1). The mixture was then mixed with the pore-forming agent (2% graphite, 1% graphene precursor, D50 12 μm, D90 20 μm) and 1% binder (hydroxypropyl methylcellulose: methylcellulose = 1:1) to obtain a uniform dry powder. Step 2: Add 31% water and 1% stearic acid by weight of the dry powder to the dry powder and mix to form a plastic mud. Step 3: Extrude the plastic clay through a honeycomb mold with 20 holes, a wall thickness of 0.75 mm, and square die holes to obtain a wet blank; Step 4: After drying the wet blank at 60℃ for 8 hours, heat it to 520℃ in air at 5℃ / min and keep it at that temperature for 8 hours for calcination treatment. After cooling in the furnace, the honeycomb vanadium-based denitrification catalyst product is obtained.

[0035] Example 12 A method for preparing a honeycomb vanadium-based denitration catalyst includes the following steps: Step 1: Take 3.5% ammonium metavanadate, 5% ammonium tungstate, and 78.5% anatase phase titanium dioxide (specific surface area 170m²) by mass percentage. 2 / g, content ≥98%), 9% nano-sized titanium powder (particle size 95nm, specific surface area 11m²). 2 / g, oxygen content 0.09%), pore-forming agent 3% (2% nutshell powder, 1% graphene precursor, D50 13μm, D90 23μm), binder 1% (carboxymethyl cellulose), add to a mixer and mix at 500r / min for 2h to obtain a uniform dry powder; Step 2: Add 35% water and 0.6% glycerin by weight of the dry powder to the dry powder and mix to form a plastic mud. Step 3: Extrude the plastic clay through a honeycomb mold with 40 holes, a wall thickness of 0.60 mm, and square die holes to obtain a wet blank; Step 4: After drying the wet blank at 60℃ for 8 hours, heat it to 570℃ in air at 5℃ / min and hold it for 6 hours for calcination treatment. After cooling in the furnace, the honeycomb vanadium-based denitrification catalyst product is obtained.

[0036] Comparative Example 1 (without nano-sized titanium powder) Step 1: Take 3% ammonium metavanadate (purity ≥ 99.0%), 2% ammonium tungstate (purity ≥ 99.0%), and 90% anatase titanium dioxide (specific surface area 180m²) by mass percentage. 2 / g, content ≥98%), pore-forming agent 3% (graphite, D50 12μm, D90 20μm), binder 2% (hydroxypropyl methylcellulose, viscosity 10000mPa) Add the s) to a mixer and mix at 400 r / min for 1.5 h to obtain a uniform dry powder; Step 2: Add 30% water and 1% lubricant (polyethylene glycol 400) by weight of the dry powder to the dry powder and mix to form a plastic slurry; Step 3: Extrude the plastic clay through a square honeycomb mold with 90 holes, a wall thickness of 0.3 mm, to obtain a wet blank; Step 4: After drying the wet blank at 80℃ for 6 hours, heat it to 500℃ in air at 2℃ / min and hold it for 8 hours for calcination. After cooling in the furnace, the catalyst product is obtained.

[0037] Comparative Example 2 (without nano-sized titanium powder) A method for preparing a honeycomb vanadium-based denitration catalyst includes the following steps: Step 1: Take 1% ammonium metavanadate (purity ≥ 99.0%), 2% ammonium tungstate (purity ≥ 99.0%), and 91% anatase titanium dioxide (specific surface area 180m²) by mass percentage. 2 / g, content ≥98%), pore-forming agent 3% (graphite, D50 12μm, D90 20μm), binder 3% (hydroxypropyl methylcellulose, viscosity 10000mPa) Add the s) to a mixer and mix at 400 r / min for 1.5 h to obtain a uniform dry powder; Step 2: Add 30% water and 1% lubricant (polyethylene glycol 400) by weight of the dry powder to the dry powder and mix to form a plastic slurry; Step 3: Extrude the clay through a square honeycomb mold with 90 holes, a wall thickness of 0.3 mm, to obtain a wet blank; Step 4: After the wet blank is dried at 80℃ for 6 hours, it is heated to 500℃ in air at a rate of 2℃ / min and held at that temperature for 8 hours for calcination. After cooling in the furnace, the catalyst product is obtained.

[0038] Comparative Example 3 (without nano-sized titanium powder) A method for preparing a honeycomb vanadium-based denitration catalyst includes the following steps: Step 1: Take ammonium metavanadate 0.8% (purity ≥ 99.0%), ammonium tungstate 4% (purity ≥ 99.0%), and anatase titanium dioxide 89.2% (specific surface area 180m²) by mass percentage. 2 / g, content ≥98%), pore-forming agent 3% (graphite, D50 12μm, D90 20μm), binder 3% (hydroxypropyl methylcellulose, viscosity 10000mPa) Add the s) to a mixer and mix at 400 r / min for 1.5 h to obtain a uniform dry powder; Step 2: Add 30% water and 1% lubricant (polyethylene glycol 400) by weight of the dry powder to the dry powder and mix to form a plastic slurry; Step 3: Extrude the clay through a square honeycomb mold with 90 holes, a wall thickness of 0.3 mm, to obtain a wet blank; Step 4: After the wet blank is dried at 80℃ for 6 hours, it is heated to 500℃ in air at a rate of 2℃ / min and held at that temperature for 8 hours for calcination. After cooling in the furnace, the catalyst product is obtained.

[0039] Comparative Example 4 (without nano-sized titanium powder) A method for preparing a honeycomb vanadium-based denitration catalyst includes the following steps: Step 1: Take 0.6% ammonium metavanadate (purity ≥ 99.0%), 5% ammonium tungstate (purity ≥ 99.0%), and 88.4% anatase titanium dioxide (specific surface area 180m²) by mass percentage. 2 / g, content ≥98%), pore-forming agent 3% (graphite, D50 12μm, D90 20μm), binder 3% (hydroxypropyl methylcellulose, viscosity 10000mPa) Add the s) to a mixer and mix at 400 r / min for 1.5 h to obtain a uniform dry powder; Step 2: Add 30% water and 1% lubricant (polyethylene glycol 400) by weight of the dry powder to the dry powder and mix to form a plastic slurry; Step 3: Extrude the clay through a square honeycomb mold with 90 holes, a wall thickness of 0.3 mm, to obtain a wet blank; Step 4: After the wet blank is dried at 80℃ for 6 hours, it is heated to 500℃ in air at a rate of 2℃ / min and held at that temperature for 8 hours for calcination. After cooling in the furnace, the catalyst product is obtained.

[0040] The catalysts obtained in the above examples and comparative examples were subjected to the following tests: (1) Catalyst porosity and wear strength test According to DL / T 1286-2021 "Technical Specification for Testing Catalysts for Flue Gas Denitrification in Thermal Power Plants" 5.1.4 and 5.2.1, the porosity and compressive strength of the calcined catalyst products were tested using vernier calipers and a pressure testing machine.

[0041] Table 1. Test results of catalyst porosity and compressive strength

[0042] To objectively evaluate the technical advantages of the present invention, we first selected honeycomb catalysts of the same specifications (wall thickness of 0.3 mm, number of holes of 90, height of 300 mm) for direct comparison, namely Example 1 and Comparative Examples 1 to 4.

[0043] As can be seen from Table 1, under similar porosity conditions (approximately 74%), the axial compressive strength of Example 1 is 6.6 MPa, while the axial compressive strength of Comparative Examples 1-4 is only 3.0-3.3 MPa, indicating that the addition of nano-sized titanium powder significantly improves mechanical strength.

[0044] Furthermore, Examples 2-12 demonstrate the performance of catalysts with different formulations and specifications (18-90 pores, wall thickness 0.3-0.8 mm). Despite the differences in geometry, all examples with added nanoscale titanium powder exhibited higher axial compressive strength (≥5.3 MPa), significantly higher than the comparative examples without added nanoscale titanium powder. This further demonstrates the universality of the reinforcing effect of nanoscale titanium powder.

[0045] Further analysis of the data revealed that with the increase in the amount of nano-sized titanium powder added (e.g., from 3% in Example 2 to 10% in Example 1), the catalyst achieved a synergistic improvement in mechanical strength while maintaining a high porosity. This breakthrough effect stems from the unique role of nano-sized titanium powder in the calcination process: its oxidation exothermic peak temperature (480~530℃) is highly matched with the decomposition temperature range of ammonium metavanadate (450~550℃) (temperature difference ≤30℃). This synergistic effect promotes the formation of stronger chemical bonds and calcination structures between the active component and the support, thereby constructing a catalyst framework with a significantly enhanced effect in situ, effectively resolving the contradiction between high porosity and high strength.

[0046] (2) Denitrification efficiency and SO2 oxidation rate detection The catalysts prepared in Examples 1-12 and Comparative Examples 1-4 were loaded into a fixed-bed reactor, and feed gas was introduced into the reactor to carry out a denitrification reaction. The test conditions were: NO 500 mg / Nm³. 3 O2 10%, SO2 2000 mg / Nm 3 10% H2O, NH3 / NO molar ratio of 1.0, N2 as balance gas, space velocity of 5000 h⁻¹ -1 The catalyst has dimensions of 150×150mm, a height of 300mm, and a wall thickness of 0.3mm. The concentrations of NOx at the inlet and outlet were measured at 380℃ using a Testo portable flue gas analyzer and ion chromatography. The denitrification performance and SO2 oxidation rate of different catalysts are shown in Table 2.

[0047] Table 2. Results of catalyst denitrification efficiency and SO2 oxidation rate.

[0048] As can be seen from Table 2, which shows the test results of catalyst denitrification efficiency and SO2 oxidation rate, compared with the comparative examples 1-4 without the addition of nano-sized titanium powder, the catalysts of Examples 1-12 of this invention, while maintaining a denitrification efficiency of ≥94.0%, all have an SO2 oxidation rate of ≤0.8% (minimum 0.25%), which is significantly lower than that of the comparative examples (≥0.84%). This indicates that by adding nano-sized titanium powder, this invention not only significantly improves the mechanical strength of the catalyst but also effectively controls the SO2 oxidation rate.

[0049] Compared with the prior art, the present invention achieves the following: Synergistic optimization of strength and structure: Through the in-situ oxidation effect of nanoscale titanium powder (matching the decomposition temperature of ammonium metavanadate and ammonium tungstate), a dense chemical bond is formed, so that the catalyst has an axial compressive strength of ≥5.0MPa under the premise of porosity ≥70% and wall thickness of 0.3~0.8mm, which solves the contradiction between high porosity, thin wall and high strength. Excellent catalytic performance: It simultaneously ensures high denitrification efficiency (≥92%) and low SO2 oxidation rate (≤0.8%), avoiding SO2 oxidation to generate ammonium sulfate that clogs the catalyst pores; High process compatibility: Based on conventional extrusion molding process, only the raw materials and heat treatment process are optimized, without the need for complex equipment modification, and it can be mass-produced.

[0050] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A honeycomb vanadium-based denitration catalyst, characterized in that, It consists of the following components by weight percentage: Ammonium metavanadate 0.1%~4%, ammonium tungstate 2%~5%, nano-sized titanium powder 3%~10%, pore-forming agent 3%~4.5%, binder 1%~2.5%, the remainder is titanium dioxide; The particle size of the nano-sized titanium powder is 50~100 nm.

2. The honeycomb vanadium-based denitration catalyst according to claim 1, characterized in that, The specific surface area of ​​the nanoscale titanium powder is 10~20m². 2 / g, oxygen content ≤0.1%.

3. The honeycomb vanadium-based denitration catalyst according to claim 1, characterized in that, The mass ratio of the nano-sized titanium powder to titanium dioxide is 1:7.5 to 1:28.

3.

4. The honeycomb vanadium-based denitration catalyst according to claim 1, characterized in that, The pore-forming agent is at least one of graphite, graphene precursor, and nutshell powder; the particle size D50 of the pore-forming agent is 10~15μm, and D90≤25μm.

5. The honeycomb vanadium-based denitration catalyst according to claim 1, characterized in that, The binder is at least one of methylcellulose, hydroxypropyl methylcellulose and carboxymethylcellulose.

6. A method for preparing a honeycomb vanadium-based denitration catalyst as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Ammonium metavanadate, ammonium tungstate, titanium dioxide, nano-sized titanium powder, pore-forming agent and binder are mixed according to the mass percentage to obtain dry-based powder; Water and lubricant are added to the dry powder and kneaded to obtain a plastic slurry; The plastic clay is extruded through a honeycomb mold to obtain a wet blank; The wet blank was sequentially dried and calcined to obtain the honeycomb vanadium-based denitrification catalyst; During the calcination process, the oxidation exothermic peak temperature of the nano-sized titanium powder is 480~530℃, the decomposition temperature range of ammonium metavanadate is 450~550℃, and the temperature difference between the two is ≤30℃.

7. The method according to claim 6, characterized in that, The amount of water added is 30% to 35% of the total mass of the dry powder; the amount of lubricant added is 0.5% to 1% of the total mass of the dry powder; the lubricant is at least one of polyethylene glycol 400, rapeseed oil, glycerin and stearic acid.

8. The method according to claim 6, characterized in that, The honeycomb mold has 18 to 90 holes and a wall thickness of 0.3 to 0.8 mm; the shape of the mold holes is square, hexagonal, or triangular.

9. The method according to claim 6, characterized in that, The calcination process is carried out in an air atmosphere at a temperature of 500-600°C and a holding time of 4-8 hours.

10. The method according to claim 9, characterized in that, The heating rate of the calcination treatment is 1~5℃ / min.

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