A composite catalyst for synergistic denitrification and dioxin removal, as well as its preparation method and application

Abstract

The present invention belongs to the field of environmental protection, and in particular relates to a composite catalyst for synergistic denitrification and dioxin removal, as well as its preparation method and application. The composite catalyst provided by the present invention is prepared according to the following steps: a) mixing a precursor, a carrier, an additive, and water to obtain a base mixture; b) mixing the base mixture, an active agent, a binder, a humectant, a pore-forming agent, and water to obtain a slurry; in step b), the active agents include active agent A, active agent B, and active agent C, where active agent A is methylcellulose, polyvinylidene fluoride, polyacrylonitrile, and polyetherimide; active agent B is phosphoric acid and nitric acid; and active agent C is nickel oxide, tin oxide, and molybdenum oxide; c) shaping, drying, and calcining the slurry to obtain the composite catalyst. The present invention improves the stability of the catalyst, increases the hydrophobicity, acid sites, and oxygen vacancy sites of the catalyst, reduces the operating temperature of the catalyst, and improves the catalytic efficiency by optimizing the composition and preparation process of the catalyst.

Description

Technical Field

[0001] The present invention belongs to the field of environmental protection, and in particular relates to a composite catalyst for coordinated denitration and dedioxin removal, and a preparation method and application thereof. Background Art

[0002] The combustion of fossil fuels produces large amounts of nitrogen oxides, a major cause of environmental pollution problems such as photochemical smog, haze, and acid rain. PCDD / Fs, short for polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), are highly toxic. Exposure or inhalation can cause serious reproductive and developmental problems, affect the immune system, disrupt hormone regulation, and even cause cancer. Dioxins are also persistent, stable, and difficult to degrade chlorinated organic compounds. Due to the hazards of nitrogen oxides and dioxins, strict laws and regulations have been enacted both domestically and internationally to control their emissions, particularly dioxins.

[0003] Currently, nitrogen oxides are widely removed using selective catalytic reduction (SCR) technology. Nitrogen oxides in the gas are reduced to nitrogen and water by ammonia (urea, liquid ammonia) over the vanadium-titanium catalyst within the SCR unit. Dioxins, on the other hand, are mostly removed using activated carbon adsorption technology. However, this technology has issues such as high long-term operating costs, incomplete treatment of low-concentration dioxins (it merely transfers the dioxins without eliminating them from the environment), and the risk of secondary pollution from activated carbon that has adsorbed dioxins. Removing these two pollutants using separate technologies or equipment would incur high investment and operating costs. Developing a catalyst that synergistically removes nitrogen oxides and dioxins would not only decompose the pollutants into nitrogen, water, carbon dioxide, and hydrogen chloride, addressing the pollution problem at its source, but also reduce the investment and operating costs of pollutant control.

[0004] Most existing composite catalysts for synergistic denitrification and dioxin removal employ vanadium-titanium catalysts doped with precious metals or rare metals to improve dioxin removal efficiency and reduce the operating temperature of the catalyst. However, in actual application, these catalysts suffer from complex preparation processes, low yields, unstable structures, reduced catalytic activity after lowering the operating temperature, and poor water resistance. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a composite catalyst for synergistic denitrification and dioxin removal, as well as its preparation method and application. The catalyst prepared by the present invention has good stability and hydrophobicity, rich acid sites and oxygen vacancies, low operating temperature and high catalytic efficiency.

[0006] The present invention provides a method for preparing a composite catalyst for synergistic denitration and dioxin removal, comprising the following steps:

[0007] a) mixing the precursor, carrier, additive and water to obtain a basic mixture;

[0008] In step a), the precursor is ammonium metavanadate, the carrier is anatase titanium dioxide and graphene, and the auxiliary agent is one or more of methyl monoethanolamine, monoethanolamine, and diethanolamine; the molar ratio of the precursor to the auxiliary agent is 1:(0.15-0.2);

[0009] b) mixing the basic mixture, active agent, binder, moisturizing agent, pore former and water to obtain a slurry;

[0010] In step b), the active agent includes active agent A, active agent B and active agent C, the active agent A is one or more of methyl cellulose, polyvinylidene fluoride, polyacrylonitrile and polyetherimide, the active agent B is a mixture of phosphoric acid and nitric acid, and the active agent C is a mixture of nickel oxide, tin oxide and molybdenum oxide; the humectant is at least one of stearic acid and lactic acid;

[0011] c) forming, drying and calcining the clay material to obtain a composite catalyst.

[0012] Preferably, in step a), the graphene accounts for 3-15 wt % in the carrier.

[0013] Preferably, in step a), the auxiliary agent accounts for 15-22 wt% of the total mass of the auxiliary agent and water; the total mass of the auxiliary agent and water accounts for 3-8 wt% of the total mass of the precursor and the carrier.

[0014] Preferably, in step b), the amount of the active agent A is 1~2wt% of the mass of the basic mixture; the amount of phosphoric acid in the active agent B is 0.5~2wt% of the mass of the basic mixture, and the amount of nitric acid is 1~2wt% of the mass of the basic mixture; the amount of nickel oxide in the active agent C is 0.5~2wt% of the mass of the basic mixture, the amount of tin oxide is 1~2wt% of the mass of the basic mixture, and the amount of molybdenum oxide is 0.5~1wt% of the mass of the basic mixture.

[0015] Preferably, in step b), the binder is one or more of polyethylene oxide, methyl silicone resin, phenolic resin, epoxy resin and polyurethane resin; the amount of the binder is 3-5 wt% of the mass of the basic mixture.

[0016] Preferably, in step b), the amount of the moisturizing agent is 0.5-2 wt % of the mass of the basic mixture.

[0017] Preferably, in step b), the pore-forming agent is one or more of polyethylene glycol, polypropylene carbonate, polypropionaldehyde, polyvinyl pyrrolidone and aker wax; and the amount of the pore-forming agent is 2-5 wt% of the mass of the basic mixture.

[0018] Preferably, in step c), the calcination process specifically includes:

[0019] The temperature is raised from the calcination starting temperature to the first calcination temperature, kept warm for a first time, then continued to be raised to the second calcination temperature, kept warm for a second time, and finally raised to the third calcination temperature, kept warm for a third time; wherein, the calcination starting temperature is 10~40°C, the first calcination temperature is 160~200°C, the rate of raising the temperature to the first calcination temperature is 0.2~0.5°C / min, the first time is 2~4h, the second calcination temperature is 500~600°C, the rate of raising the temperature to the second calcination temperature is 0.5~1°C / min, the second time is 1~3h, the third calcination temperature is 550~650°C, the rate of raising the temperature to the third calcination temperature is 2~4°C / min, and the third time is 1~3h.

[0020] The present invention provides a composite catalyst for synergistic denitration and dioxin removal, which is prepared according to the preparation method described in the above technical solution.

[0021] The present invention provides a method for collaborative denitrification and dioxin removal, comprising the following steps:

[0022] In the presence of a catalyst, nitrogen oxides and dioxins in the gas are synergistically removed; the catalyst is the composite catalyst for synergistic denitration and dioxin removal described in the above technical solution.

[0023] Compared with the prior art, the present invention provides a composite catalyst for synergistic denitration and dioxin removal, as well as a preparation method and application thereof. The composite catalyst provided by the present invention is prepared according to the following steps: a) mixing a precursor, a carrier, an auxiliary agent and water to obtain a basic mixture; in step a), the precursor is ammonium metavanadate, the carrier is anatase titanium dioxide and graphene, and the auxiliary agent is one or more of methylmonoethanolamine, monoethanolamine and diethanolamine; the molar ratio of the precursor to the auxiliary agent is 1:(0.15-0.2); b) mixing the basic mixture, an active agent, a binder, a moisturizing agent, a pore-forming agent and water to obtain a mud material; in step b), the active agent includes active agent A, active agent B and active agent C, the active agent A is one or more of methylcellulose, polyvinylidene fluoride, polyacrylonitrile and polyetherimide, the active agent B is a mixture of phosphoric acid and nitric acid, and the active agent C is a mixture of nickel oxide, tin oxide and molybdenum oxide; the moisturizing agent is at least one of stearic acid and lactic acid; c) the mud material is shaped, dried and calcined to obtain the composite catalyst. By optimizing the catalyst's composition and preparation process, the present invention enhances catalyst stability, increases hydrophobicity, acid sites, and oxygen vacancies, reduces the catalyst's operating temperature, and improves catalytic efficiency. Experimental results demonstrate that the catalyst prepared in this invention is suitable for synergistic denitration and dioxin removal in the temperature range of 160°C to 300°C. At temperatures between 160°C and 200°C, the denitration efficiency exceeds 98.5%, and the dioxin removal efficiency exceeds 98.8%. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0025] Figure 1 Schematic diagram of a test bench for testing catalyst performance according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0027] The present invention provides a method for preparing a composite catalyst for synergistic denitration and dioxin removal, comprising the following steps:

[0028] a) mixing the precursor, carrier, additive and water to obtain a basic mixture;

[0029] b) mixing the basic mixture, active agent, binder, moisturizing agent, pore former and water to obtain a slurry;

[0030] c) forming, drying and calcining the clay material to obtain a composite catalyst.

[0031] In the preparation method provided by the present invention, in step a), the precursor is ammonium metavanadate, and the auxiliary agent is one or more of methyl monoethanolamine, monoethanolamine and diethanolamine; the molar ratio of the precursor to the auxiliary agent is 1:(0.15~0.2), specifically 1:0.15, 1:0.16, 1:0.17, 1:0.18, 1:0.19 or 1:0.2.

[0032] In the preparation method provided by the present invention, in step a), the carrier is anatase titanium dioxide and graphene; the particle size of the anatase titanium dioxide is preferably 0.1-2 μm, more preferably 0.3-1 μm; the particle size of the graphene is preferably 5-50 μm, more preferably 10-30 μm; the proportion of the graphene in the carrier is preferably 3-15 wt%, specifically 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 4.85 wt%, 5 wt%, 5.5 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, 8.5 wt%, 9 wt%, 9.5 wt%, 10 wt%, 10.5 wt%, 11 wt%, 11.5 wt%, 12 wt%, 12.5 wt%, 13 wt%, 13.5 wt%, 14 wt%, 14.5 wt% or 15 wt%.

[0033] In the preparation method provided by the present invention, in step a), the auxiliary agent preferably accounts for 15-22wt% of the total mass of the auxiliary agent and water, specifically 15wt%, 16wt%, 16.7wt%, 17wt%, 18wt%, 19wt%, 20wt%, 21wt% or 22wt%; the total mass of the auxiliary agent and water preferably accounts for 3-8wt% of the total mass of the precursor and the carrier, specifically 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt% or 8wt%.

[0034] In the preparation method provided herein, in step a), the mixing process preferably includes first dissolving the additive in water to form a solution, and then mixing the solution with the precursor and the carrier. In the present invention, the mixing is preferably performed in a planetary mixer; the mixing time is preferably 1 to 5 hours, specifically 1 hour, 2 hours, 3 hours, 4 hours, or 5 hours.

[0035] In the preparation method provided by the present invention, in step b), the active agent includes active agent A, active agent B and active agent C, wherein the active agent A is one or more of methyl cellulose, polyvinylidene fluoride, polyacrylonitrile and polyetherimide, the active agent B is a mixture of phosphoric acid and nitric acid, and the active agent C is a mixture of nickel oxide, tin oxide and molybdenum oxide. In the present invention, the number average molecular weight of the methyl cellulose is preferably 50,000 to 200,000, specifically 50,000, 100,000, 150,000 or 200,000; the number average molecular weight of the polyetherimine is preferably 500 to 2,000, specifically 500, 1,000, 1,500 or 2,000; the particle size of the nickel oxide is preferably 5 to 100 μm, more preferably 10 to 50 μm; the particle size of the tin oxide is preferably 5 to 100 μm, more preferably 10 to 50 μm; and the particle size of the molybdenum oxide is preferably 5 to 100 μm, more preferably 10 to 50 μm.

[0036] In the preparation method provided by the present invention, in step b), the amount of the active agent A is preferably 1-2 wt% of the mass of the basic mixture, specifically 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt% or 2 wt%.

[0037] In the preparation method provided by the present invention, in step b), the amount of phosphoric acid in the active agent B is preferably 0.5-2 wt% of the mass of the basic mixture, specifically 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt% or 2 wt%; the amount of nitric acid in the active agent B is preferably 1-2 wt% of the mass of the basic mixture, specifically 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt% or 2 wt%.

[0038] In the preparation method provided by the present invention, in step b), the amount of nickel oxide in the active agent C is preferably 0.5-2wt% of the mass of the basic mixture, specifically 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt% or 2wt%; the amount of tin oxide in the active agent C is preferably 1-2wt% of the mass of the basic mixture. , specifically 1wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt% or 2wt%; the amount of molybdenum oxide in the active agent C is preferably 0.5~1wt% of the mass of the basic mixture, specifically 0.5wt%, 0.55wt%, 0.6wt%, 0.65wt%, 0.7wt%, 0.75wt%, 0.8wt%, 0.85wt%, 0.9wt%, 0.95wt% or 1wt%.

[0039] In the preparation method provided by the present invention, in step b), the binder is preferably one or more of polyethylene oxide, methyl silicone resin, phenolic resin, epoxy resin and polyurethane resin; the number average molecular weight of the binder is preferably 50,000 to 500,000, specifically 50,000, 100,000, 150,000, 200,000, 250,000, 300,000, 350,000, 400,000, 450,000 or 500,000.

[0040] In the preparation method provided by the present invention, in step b), the amount of the binder is preferably 3-5 wt% of the mass of the basic mixture, specifically 3 wt%, 3.1 wt%, 3.2 wt%, 3.3 wt%, 3.4 wt%, 3.5 wt%, 3.6 wt%, 3.7 wt%, 3.8 wt%, 3.9 wt%, 4 wt%, 4.1 wt%, 4.2 wt%, 4.3 wt%, 4.4 wt%, 4.5 wt%, 4.6 wt%, 4.7 wt%, 4.8 wt%, 4.9 wt% or 5 wt%.

[0041] In the preparation method provided by the present invention, in step b), the moisturizing agent is at least one of stearic acid and lactic acid.

[0042] In the preparation method provided by the present invention, in step b), the amount of the humectant is preferably 0.5-2 wt% of the mass of the basic mixture, specifically 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt% or 2 wt%.

[0043] In the preparation method provided by the present invention, in step b), the pore-forming agent is preferably one or more of polyethylene glycol, polypropylene carbonate, polypropionaldehyde, polyvinyl pyrrolidone and aker wax; wherein the number average molecular weight of the polyethylene glycol is preferably 4000-8000, specifically 4000, 5000, 6000, 7000 or 8000; the brand of the polyvinyl pyrrolidone is preferably K30.

[0044] In the preparation method provided by the present invention, in step b), the amount of the pore-forming agent is preferably 2-5 wt% of the mass of the basic mixture, specifically 2 wt%, 2.1 wt%, 2.2 wt%, 2.3 wt%, 2.4 wt%, 2.5 wt%, 2.6 wt%, 2.7 wt%, 2.8 wt%, 2.9 wt%, 3 wt%, 3.1 wt%, 3.2 wt%, 3.3 wt%, 3.4 wt%, 3.5 wt%, 3.6 wt%, 3.7 wt%, 3.8 wt%, 3.9 wt%, 4 wt%, 4.1 wt%, 4.2 wt%, 4.3 wt%, 4.4 wt%, 4.5 wt%, 4.6 wt%, 4.7 wt%, 4.8 wt%, 4.9 wt% or 5 wt%.

[0045] In the preparation method provided by the present invention, in step b), the mixing is preferably carried out in a planetary mixer; the mixing time is preferably 1 to 5 hours, specifically 1 hour, 2 hours, 3 hours, 4 hours or 5 hours.

[0046] In the preparation method provided by the present invention, in step b), the moisture content of the mud is preferably 18-25wt%, specifically 18wt%, 18.5wt%, 19wt%, 19.5wt%, 20wt%, 20.5wt%, 21wt%, 21.5wt%, 22wt%, 22.5wt%, 23wt%, 23.5wt%, 24wt%, 24.5wt% or 25wt%.

[0047] In the preparation method provided by the present invention, in step c), the molding and drying refers to placing the clay material into an extruder for extrusion molding, and then placing it in an oven for drying; wherein, the material obtained by the extrusion molding is preferably a granular material; the shape of the granular material is preferably cylindrical, and the cylindrical radius is preferably 10-20 mm, specifically 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm or 20 mm, and the cylindrical length is preferably 20-30 mm, specifically 20 mm, 21mm, 22mm, 23mm, 24mm, 25mm, 26mm, 27mm, 28mm, 29mm or 30mm; the drying temperature is preferably 100-110°C, specifically 100°C, 101°C, 102°C, 103°C, 104°C, 105°C, 106°C, 107°C, 108°C, 109°C or 110°C; the drying time is preferably 5-15h, specifically 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h or 15h.

[0048] In the preparation method provided by the present invention, in step c), the specific process of calcination preferably includes: heating from the calcination starting temperature to the first calcination temperature, keeping the temperature for the first time, then continuing to heat up to the second calcination temperature, keeping the temperature for the second time, and finally heating up to the third calcination temperature, keeping the temperature for the third time. Wherein, the calcination starting temperature is preferably 10~40℃, specifically 10℃, 15℃, 20℃, 25℃, 30℃, 35℃ or 40℃; the first calcination temperature is preferably 160~200℃, specifically 160℃, 165℃, 170℃, 175℃, 180℃, 185℃, 190℃, 195℃ or 200℃; the rate of heating to the first calcination temperature is preferably 0.2~0.5℃ / min, specifically 0.2℃ / min, 0.25℃ / min, 0.3℃ / min, 0.35℃ / min, 0.4 ℃ / min, 0.45℃ / min or 0.5℃ / min; the first time is preferably 2-4h, specifically 2h, 2.3h, 2.5h, 2.7h, 3h, 3.2h, 3.5h, 3.7h or 4h; the second calcination temperature is preferably 500-600℃, specifically 500℃, 510℃, 520℃, 530℃, 540℃, 550℃, 560℃, 570℃, 580℃, 590℃ or 600℃; the rate of heating to the second calcination temperature is preferably 0.5-1℃ / min, specifically 0.5℃ / min, 0.55℃ / min, 0.6℃ / min, 0.65℃ / min, 0.7℃ / min, 0.75℃ / min, 0.8℃ / min, 0.85℃ / min, 0.9℃ / min, 0.95℃ / min or 1℃ / min; the second time is preferably 1-3h, specifically 1h, 1.2h, 1.5h, 1.7h, 2h, 2.3h, 2.5h, 2.7h or 3h; the third calcination temperature is preferably 550-650℃, specifically 550℃, 560℃, 570℃, 580℃ , 590°C, 600°C, 610°C, 620°C, 630°C, 640°C or 650°C; the rate of heating to the third calcination temperature is preferably 2-4°C / min, specifically 2°C / min, 2.3°C / min, 2.5°C / min, 2.7°C / min, 3°C / min, 3.2°C / min, 3.5°C / min, 3.7°C / min or 4°C / min; the third time is preferably 1-3 hours, specifically 1 hour, 1.2 hours, 1.5 hours, 1.7 hours, 2 hours, 2.3 hours, 2.5 hours, 2.7 hours or 3 hours. After the calcination is completed, the temperature is naturally cooled to ambient temperature.

[0049] The present invention also provides a composite catalyst for synergistic denitration and dioxin removal, and the composite catalyst is prepared according to the preparation method described in the above technical solution.

[0050] The present invention also provides a method for collaborative denitrification and dioxin removal, comprising the following steps:

[0051] In the presence of a catalyst, nitrogen oxides and dioxins in the gas are synergistically removed; the catalyst is the composite catalyst for synergistic denitration and dioxin removal described in the above technical solution.

[0052] In the method for collaborative denitration and dioxin removal provided by the present invention, the nitrogen oxides (NO X ) content is preferably 500-2000ppm, specifically 500ppm, 600ppm, 700ppm, 800ppm, 900ppm, 1000ppm, 1100ppm, 1200ppm, 1300ppm, 1400ppm, 1500ppm, 1600ppm, 1700ppm, 1800ppm, 1900ppm or 2000ppm.

[0053] In the method for collaborative denitrification and dioxin removal provided by the present invention, the dioxin content in the gas is preferably 10-100 ppm, specifically 10 ppm, 15 ppm, 20 ppm, 25 ppm, 30 ppm, 35 ppm, 40 ppm, 45 ppm, 50 ppm, 55 ppm, 60 ppm, 65 ppm, 70 ppm, 75 ppm, 80 ppm, 85 ppm, 90 ppm, 95 ppm or 100 ppm.

[0054] In the method for coordinated denitrification and dioxin removal provided by the present invention, the content of oxygen (O2) in the gas is preferably 10-20 vol%, specifically 10 vol%, 11 vol%, 12 vol%, 13 vol%, 14 vol%, 15 vol%, 16 vol%, 16.8 vol%, 17 vol%, 18 vol%, 19 vol% or 20 vol%.

[0055] In the method for collaborative denitrification and dioxin removal provided by the present invention, the content of water (H2O) in the gas is preferably 5-15 vol%, specifically 5 vol%, 6 vol%, 7 vol%, 8 vol%, 9 vol%, 9.5 vol%, 10 vol%, 11 vol%, 12 vol%, 13 vol%, 14 vol% or 15 vol%.

[0056] In the method for collaborative denitrification and dioxin removal provided by the present invention, the collaborative removal is carried out in the presence of a reducing agent; the reducing agent is preferably ammonia; the content of ammonia in the gas is preferably 500~2000ppm, specifically 500ppm, 600ppm, 700ppm, 800ppm, 900ppm, 1000ppm, 1100ppm, 1200ppm, 1300ppm, 1400ppm, 1500ppm, 1600ppm, 1700ppm, 1800ppm, 1900ppm or 2000ppm.

[0057] In the method for collaborative denitrification and dioxin removal provided by the present invention, the temperature of the collaborative removal is preferably 160~300℃, specifically 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃ or 300℃.

[0058] The present invention optimizes the catalyst's composition and preparation process to enhance catalyst stability, increase catalyst hydrophobicity, acid sites, and oxygen vacancies, lower the catalyst's operating temperature, and improve catalytic efficiency. More specifically, the present invention has the following key features and advantages:

[0059] 1) The molar ratio of the added additive to the precursor is (0.15-0.20):1. When calcined within this range, the optimal crystallinity is achieved, which reduces the resistance during material transfer and ensures structural stability, thereby reducing catalyst loss and extending catalyst service life.

[0060] 2) The added active agent A is an oily organic substance, which increases the viscosity and hydrophobicity at the same time, thereby improving the water resistance of the catalyst and the adsorption capacity of dioxins, thereby improving the dioxin removal rate;

[0061] 3) The nitrogen element in the active agent B will react with the carbon element in the graphene to form carbon nitride (C3N4) when calcined at 450-500°C. Combining with vanadium will enhance the catalytic effect and increase the dioxin removal rate;

[0062] 4) The phosphate in the active agent B increases the acid sites and oxygen vacancies of the catalyst, thereby improving the removal rate of dioxins and nitrogen oxides;

[0063] 5) Adding Ni, Sn and Mo oxides in the activator C can reduce the chemical energy of the reaction and help improve the catalyst efficiency;

[0064] 6) Adding lactic acid as a moisturizer can prevent the catalyst from cracking during drying and calcination, thereby increasing the catalyst yield and improving economic benefits.

[0065] For the purpose of greater clarity, the present invention is described in detail with reference to the following examples.

[0066] Example 1

[0067] (1) The preparation method of the composite catalyst for synergistic denitrification and dioxin removal mainly includes four steps: preparation of basic mixture, preparation of slurry, molding and drying, and calcination, as follows:

[0068] 1. Preparation of the base mixture: Dissolve an appropriate amount of diethanolamine in water to form an aqueous solution with a diethanolamine content of 16.7 wt%; add anatase titanium dioxide powder (particle size 0.3-1 μm), graphene powder (particle size 10-30 μm) and ammonium metavanadate to the aqueous solution, and stir with a planetary stirrer for 2 h; wherein the mass of the graphene powder accounts for 4.85 wt% of the total mass of the anatase titanium dioxide powder and the graphene powder, the molar ratio of ammonium metavanadate to diethanolamine is 1:0.18, and the mass of the aqueous solution accounts for 6 wt% of the total mass of the anatase titanium dioxide powder, the graphene powder and the ammonium metavanadate.

[0069] 2. Preparation of mud: Add polyoxyethylene (number average molecular weight 300,000), polyethylene glycol (number average molecular weight 6,000), lactic acid, methyl cellulose (number average molecular weight 100,000), phosphoric acid, nitric acid, nickel oxide (particle size 10-50 μm), tin oxide (particle size 10-50 μm) and molybdenum oxide (particle size 10-50 μm) to the above basic mixture, add appropriate amount of water, and stir with a planetary mixer for 2 hours; wherein, the amount of polyoxyethylene added is 3.3wt% of the mass of the basic mixture, the amount of polyethylene glycol added is 10wt% of the mass of the basic mixture, and the amount of methyl cellulose added is 10wt% of the mass of the basic mixture. The amount of added phosphoric acid is 0.7wt% of the basic mixture mass, the amount of added nitric acid is 1.0wt% of the basic mixture mass, the amount of added nickel oxide is 0.8wt% of the basic mixture mass, the amount of added tin oxide is 1.1wt% of the basic mixture mass and the amount of added molybdenum oxide is 0.8wt% of the basic mixture mass, the moisture content of the prepared mud is 20wt%.

[0070] 3. Molding and drying: put the prepared mud into an extruder and extrude it into granules. The granules are cylindrical with a radius of 15 mm and a length of 25 mm. Then put the granules into an oven at 105°C and dry them for 10 hours.

[0071] 4. Calcination: Place the dried particles in a muffle furnace and set the heating program as follows: 30℃→180℃ with a heating rate of 0.3℃ / min, and maintain the temperature at 180℃ for 3h; 180℃→560℃ with a heating rate of 1℃ / min, and maintain the temperature at 560℃ for 2h; 560℃→600℃ with a heating rate of 3℃ / min, and maintain the temperature at 600℃ for 2h, then cool naturally to room temperature, take out, and place in a dry place for use.

[0072] (II) Catalyst performance evaluation:

[0073] The catalysts prepared above were subjected to comparative experiments in a pilot plant. The experimental setup is shown in Figure 1 The gas mixture contained 73.5% (v / v) N2, 16.8% (v / v) O2, 9.5% (v / v) H2O, 1000 ppm NOx, 1000 ppm NH3, and 50 ppm chlorobenzene. The experimental results are shown in Table 1.

[0074] Table 1 Experimental results of Example 1

[0075]

[0076] Comparative Example 1

[0077] The preparation method of the composite catalyst was referred to as Example 1, except that the molar ratio of ammonium metavanadate to diethanolamine was 1:0.1.

[0078] The catalyst performance of Comparative Example 1 was evaluated using the method of Example 1. The experimental results are shown in Table 2.

[0079] Table 2 Experimental results of Comparative Example 1

[0080]

[0081] Comparative Example 2

[0082] The preparation method of the composite catalyst was referred to as Example 1, except that the molar ratio of ammonium metavanadate to diethanolamine was 1:0.25.

[0083] The catalyst performance of Comparative Example 2 was evaluated using the method of Example 1. The experimental results are shown in Table 3.

[0084] Table 3 Experimental results of Comparative Example 2

[0085]

[0086] Comparative Example 3

[0087] The composite catalyst preparation method of Example 1 is referred to, except that the activator A (methyl cellulose) is not added, and the amounts of activators B (phosphoric acid and nitric acid) and activators C (nickel oxide, tin oxide and molybdenum oxide) are increased in proportion to make up for the missing amount of activator A.

[0088] The catalyst performance of Comparative Example 3 was evaluated using the method of Example 1. The experimental results are shown in Table 4.

[0089] Table 4 Experimental results of Comparative Example 3

[0090]

[0091] Comparative Example 4

[0092] The preparation method of the composite catalyst was referred to in Example 1, except that no nitric acid was added, only phosphoric acid was used as the component of the activator B, and the amount of phosphoric acid was adjusted to 1.7 wt % of the mass of the basic mixture.

[0093] The catalyst performance of Comparative Example 4 was evaluated using the method of Example 1. The experimental results are shown in Table 5.

[0094] Table 5 Experimental results of Comparative Example 4

[0095]

[0096] Comparative Example 5

[0097] The composite catalyst preparation method of Example 1 is referred to, except that the activator C (nickel oxide, tin oxide and molybdenum oxide) is not added, and the amounts of activator A (methyl cellulose) and activator B (phosphoric acid and nitric acid) are increased in proportion to compensate for the missing amount of activator C.

[0098] The catalyst performance of Comparative Example 5 was evaluated using the method of Example 1. The experimental results are shown in Table 6.

[0099] Table 6 Experimental results of Comparative Example 5

[0100]

[0101] Comparative Example 6

[0102] The preparation method of the composite catalyst was referred to in Example 1, except that no moisturizing agent (lactic acid) was added.

[0103] The qualified rates of the finished catalyst products of Example 1 and Comparative Example 6 are compared and the results are shown in Table 7.

[0104] Table 7 Experimental results of Example 1 and Comparative Example 6

[0105]

[0106] Example 2

[0107] (1) The preparation method of the composite catalyst for synergistic denitrification and dioxin removal mainly includes four steps: preparation of basic mixture, preparation of slurry, molding and drying, and calcination, as follows:

[0108] 1. Preparation of the base mixture: dissolve an appropriate amount of monoethanolamine in water to form an aqueous solution with a monoethanolamine content of 19.2 wt%; add anatase titanium dioxide powder (particle size 0.3-1 μm), graphene powder (particle size 10-30 μm) and ammonium metavanadate to the aqueous solution, and stir with a planetary stirrer for 2 h; wherein the mass of the graphene powder accounts for 4.85 wt% of the total mass of the anatase titanium dioxide powder and the graphene powder, the molar ratio of ammonium metavanadate to monoethanolamine is 1:0.15, and the mass of the aqueous solution accounts for 6.5 wt% of the total mass of the anatase titanium dioxide powder, the graphene powder and the ammonium metavanadate.

[0109] 2. Preparation of mud: Add polyoxyethylene (number average molecular weight 300,000), polyvinyl pyrrolidone (k30), lactic acid, methyl cellulose (number average molecular weight 100,000), phosphoric acid, nitric acid, nickel oxide (particle size 10-50 μm), tin oxide (particle size 10-50 μm) and molybdenum oxide (particle size 10-50 μm) to the above basic mixture, add appropriate amount of water, and stir with a planetary mixer for 2 hours; wherein, the amount of polyoxyethylene added is 3.8wt% of the mass of the basic mixture, the amount of polyvinyl pyrrolidone added is The amount of phosphoric acid added is 0.5wt% of the mass of the basic mixture, the amount of nitric acid added is 1.3wt% of the mass of the basic mixture, the amount of nickel oxide added is 1.6wt% of the mass of the basic mixture, the amount of tin oxide added is 1.3wt% of the mass of the basic mixture and the amount of molybdenum oxide added is 0.4wt% of the mass of the basic mixture, and the moisture content of the prepared mud is 22wt%.

[0110] 3. Molding and drying: put the prepared mud into an extruder and extrude it into granules. The granules are cylindrical with a radius of 15 mm and a length of 25 mm. Then put the granules into an oven at 105°C and dry them for 10 hours.

[0111] 4. Calcination: Place the dried particles in a muffle furnace and set the heating program as follows: 30℃→180℃ with a heating rate of 0.5℃ / min, and keep the temperature at 180℃ for 3h; 180℃→560℃ with a heating rate of 1℃ / min, and keep the temperature at 560℃ for 2h; 560℃→600℃ with a heating rate of 3℃ / min, and keep the temperature at 600℃ for 2h, then cool naturally to room temperature, take out, and place in a dry place for use.

[0112] (II) Catalyst performance evaluation:

[0113] The evaluation device is the same as that of Example 1. The experimental results of Example 2 are shown in Table 8.

[0114] Table 8 Experimental results of Example 2

[0115]

[0116] Example 3

[0117] (1) The preparation method of the composite catalyst for synergistic denitrification and dioxin removal mainly includes four steps: preparation of basic mixture, preparation of slurry, molding and drying, and calcination, as follows:

[0118] 1. Preparation of basic mixture: Take an appropriate amount of monomethylethanolamine and dissolve it in water to form an aqueous solution with an amine content of 15wt% of monomethylethanolamine; add anatase titanium dioxide powder (particle size 0.3-1μm), graphene powder (particle size 10-30μm) and ammonium metavanadate to the aqueous solution, and stir with a planetary stirrer for 2h; wherein the mass of the graphene powder accounts for 9wt% of the total mass of the anatase titanium dioxide powder and the graphene powder, the molar ratio of ammonium metavanadate to monomethylethanolamine is 1:0.20, and the mass of the aqueous solution accounts for 7.8wt% of the total mass of the anatase titanium dioxide powder, the graphene powder and the ammonium metavanadate.

[0119] 2. Preparation of mud: Add polyoxyethylene (number average molecular weight 300000), polyethylene glycol (number average molecular weight 6000), stearic acid, polyetherimide (number average molecular weight 1000), phosphoric acid, nitric acid, nickel oxide (particle size 10-50μm), tin oxide (particle size 10-50μm) and molybdenum oxide (particle size 10-50μm) to the above basic mixture, add appropriate amount of water, and stir with a planetary mixer for 2h; wherein, the amount of polyoxyethylene added is 4.5wt% of the mass of the basic mixture, and the amount of polyethylene glycol added is 5wt% of the mass of the basic mixture. The amount of phosphoric acid added is 0.9wt% of the mass of the basic mixture, the amount of nitric acid added is 1.1wt% of the mass of the basic mixture, the amount of nickel oxide added is 1.2wt% of the mass of the basic mixture, the amount of tin oxide added is 1.3wt% of the mass of the basic mixture and the amount of molybdenum oxide added is 0.8wt% of the mass of the basic mixture, and the moisture content of the prepared mud is 18.5wt%.

[0120] 3. Molding and drying: put the prepared mud into an extruder and extrude it into granules. The granules are cylindrical with a radius of 15 mm and a length of 25 mm. Then put the granules into an oven at 105°C and dry them for 10 hours.

[0121] 4. Calcination: Place the dried particles in a muffle furnace and set the heating program as follows: 30℃→180℃ with a heating rate of 0.3℃ / min, and maintain the temperature at 180℃ for 3h; 180℃→560℃ with a heating rate of 0.8℃ / min, and maintain the temperature at 560℃ for 2h; 560℃→600℃ with a heating rate of 3℃ / min, and maintain the temperature at 600℃ for 2h, then cool naturally to room temperature, take out, and place in a dry place for use.

[0122] (II) Catalyst performance evaluation:

[0123] The device is the same as that in Example 1. The experimental results of Example 3 are shown in Table 9.

[0124] Table 9 Experimental results of Example 3

[0125]

[0126] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a composite catalyst for synergistic denitration and dioxin removal, characterized in that: The following steps are involved: a) mixing the precursor, carrier, additive and water to obtain a basic mixture; In step a), the precursor is ammonium metavanadate, the carrier is anatase titanium dioxide and graphene, and the auxiliary agent is one or more of methyl monoethanolamine, monoethanolamine, and diethanolamine; the molar ratio of the precursor to the auxiliary agent is 1:(0.15-0.2); b) mixing the basic mixture, active agent, binder, moisturizing agent, pore former and water to obtain a slurry; In step b), the active agent includes active agent A, active agent B and active agent C, the active agent A is one or more of methyl cellulose, polyvinylidene fluoride, polyacrylonitrile and polyetherimide, the active agent B is a mixture of phosphoric acid and nitric acid, and the active agent C is a mixture of nickel oxide, tin oxide and molybdenum oxide; the humectant is at least one of stearic acid and lactic acid; c) forming, drying and calcining the clay material to obtain a composite catalyst.

2. The preparation method according to claim 1, characterized in that In step a), the graphene accounts for 3-15 wt % in the carrier.

3. The preparation method according to claim 1, characterized in that In step a), the auxiliary agent accounts for 15-22 wt % of the total mass of the auxiliary agent and water; the total mass of the auxiliary agent and water accounts for 3-8 wt % of the total mass of the precursor and the carrier.

4. The preparation method according to claim 1, characterized in that In step b), the amount of the active agent A is 1-2 wt% of the mass of the basic mixture; the amount of phosphoric acid in the active agent B is 0.5-2 wt% of the mass of the basic mixture, and the amount of nitric acid is 1-2 wt% of the mass of the basic mixture; the amount of nickel oxide in the active agent C is 0.5-2 wt% of the mass of the basic mixture, the amount of tin oxide is 1-2 wt% of the mass of the basic mixture, and the amount of molybdenum oxide is 0.5-1 wt% of the mass of the basic mixture.

5. The preparation method according to claim 1, characterized in that In step b), the binder is one or more of polyethylene oxide, methyl silicone resin, phenolic resin, epoxy resin and polyurethane resin; the amount of the binder is 3-5wt% of the mass of the basic mixture.

6. The preparation method according to claim 1, characterized in that In step b), the amount of the moisturizing agent is 0.5-2 wt% of the mass of the basic mixture.

7. The preparation method according to claim 1, characterized in that In step b), the pore-forming agent is one or more of polyethylene glycol, polypropylene carbonate, polypropionaldehyde, polyvinyl pyrrolidone and aker wax; the amount of the pore-forming agent is 2-5 wt% of the mass of the basic mixture.

8. The preparation method according to claim 1, characterized in that In step c), the calcination process specifically includes: The temperature is raised from the calcination starting temperature to the first calcination temperature, kept warm for a first time, then continued to be raised to the second calcination temperature, kept warm for a second time, and finally raised to the third calcination temperature, kept warm for a third time; wherein, the calcination starting temperature is 10~40°C, the first calcination temperature is 160~200°C, the rate of raising the temperature to the first calcination temperature is 0.2~0.5°C / min, the first time is 2~4h, the second calcination temperature is 500~600°C, the rate of raising the temperature to the second calcination temperature is 0.5~1°C / min, the second time is 1~3h, the third calcination temperature is 550~650°C, the rate of raising the temperature to the third calcination temperature is 2~4°C / min, and the third time is 1~3h.

9. A composite catalyst for synergistic denitrification and dioxin removal, characterized in that: It is prepared according to the preparation method according to any one of claims 1 to 8.

10. A method for collaborative denitrification and dioxin removal, characterized in that: The following steps are involved: In the presence of a catalyst, nitrogen oxides and dioxins in the gas are synergistically removed; the catalyst is the composite catalyst for synergistic denitration and dioxin removal as claimed in claim 9.

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