Preparation method and application of molecular sieve-based honeycomb monolithic denitration catalyst

Abstract

The application discloses a preparation method of a molecular sieve-based honeycomb monolithic denitration catalyst and application thereof. The molecular sieve-based honeycomb monolithic denitration catalyst is prepared by mixing a molecular sieve-based catalyst, a metal-modified natural silicon-aluminum mineral, an organic binder, an extrusion aid, a pore-forming agent, glass fiber, a structure manufacturing agent, an inorganic binder, an acid solution, a humectant and water, and performing a structured water solution process. The application uses a water-soluble polymer beam fiber as the structure manufacturing agent, reduces the negative influence of carbon deposition poisoning of the molecular sieve catalyst, realizes through connection of inner walls of the honeycomb, creates a multi-channel inner wall based on the honeycomb body, and increases the contact area and reaction contact time of the reaction gas and the embedded molecular sieve catalyst and the metal-modified natural silicon-aluminum mineral of the inner wall. The prepared denitration catalyst has high adhesion, strong adsorption and high reaction activity, can effectively overcome the barrenness of the molecular sieve catalyst, and significantly improves the extrusion smoothness and the mechanical strength after molding.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nitrogen oxide removal, and particularly relates to a preparation method of a molecular sieve-based honeycomb monolithic denitration catalyst and application thereof. BACKGROUND

[0002] Nitrogen oxide (NO x ) is one of the main atmospheric pollutants, which has great harm to human body, environment, and even social economy. Among numerous denitration technologies, the selective catalytic reduction (NH3-SCR) technology using ammonia as a reducing agent is the most mature and widely used.

[0003] The vanadium element in the traditional vanadium-tungsten-titanium catalyst has biological toxicity and environmental hazards. The current regulatory standards have more stringent requirements for denitration catalysts, and it is required to replace the vanadium-based catalyst with a new type of catalyst that is efficient, harmless, and safe. The molecular sieve catalyst has special pore structure, adjustable acidity, and excellent hydrothermal stability, and has good catalytic activity in the removal of nitrogen oxides, so it has attracted widespread attention from researchers.

[0004] In actual denitration applications, the complex working conditions require the monolithic catalyst to have certain mechanical strength while playing a catalytic role, so the extrusion molding monolithic denitration catalyst needs to be used in industry.

[0005] Patent applications US 5248643 and US 5492883 use molecular sieve-based catalysts and related binders to prepare honeycomb monolithic catalysts by blending extrusion technology, but the main body of the prepared monolithic catalyst is molecular sieve, which has high preparation cost, so it has not been widely used in industry.

[0006] Patent application CN 106457144 combines an inert carrier with a small-pore molecular sieve catalyst and adds part of a binder to overcome the molding difficulty, and finally completes the extrusion molding of the honeycomb catalyst. Patent application WO 178643 uses V2O5-WO3 / TiO2 mixed with Fe-MFI and H-MOR molecular sieves for mixed extrusion, and the results show that it has good catalytic activity. Similarly, patent application CN 108273544 also confirms that copper-iron mixed-based molecular sieves mixed with related additives for mixed extrusion have NO x conversion rate greater than 80% in the temperature range of 200-550℃. The above technologies show that the molecular sieve catalyst has good application prospects for denitration reaction, but still faces certain challenges in large-scale application. First, the molecular sieve catalyst is difficult to be molded due to its barren characteristics; second, most carriers are inert media relative to the reaction and cannot promote the reaction.

[0007] Patent application CN 115999525 A successfully prepared a honeycomb-shaped catalytic carrier using natural minerals, binders, and water. This technology lacks catalytically active components and is difficult to apply directly. Patent application CN 117839674 A introduces a method of modifying kaolin and introducing metals into the kaolin carrier using ion exchange to obtain a denitration catalyst resistant to poisoning. However, its process is relatively complex, and generates a lot of industrial wastewater, making it difficult to be applied on a large scale. Therefore, it is crucial to select a suitable catalytic carrier and modify the carrier with metals.

[0008] The honeycomb-shaped extrusion-molded monolithic catalyst has a straight-wall feature, and the reaction gas flow has a short residence time and is difficult to form turbulent flow, cross-flow, and other phenomena. The residence time is short, and the molecular sieve catalyst embedded in the inner wall is difficult to contact the reaction gas. Therefore, a pore-forming agent needs to be added for hole expansion treatment. Most studies use organic media to form pores after calcination, add a large amount of pore-forming agent, and form irregular particle pore channels connected to each other. Patent application CN 108883356 A uses starch-based pore-forming agents to form pores, forming cross-pores with particle spherical accumulation arrangement. Patent application CN 108727057 A uses cassava starch, corn straw powder, and the like as pore-forming agents to effectively widen the pore channels and prepare a silicon nitride ceramic carrier. Patent application CN 102861595 A uses paper pulp cotton and the like as a structure aid to enhance the mechanical strength and porosity of the monolithic catalyst. Such technologies face two difficulties: first, only the micro-porosity of the honeycomb is adjusted, and the honeycomb is not macro-structurally adjusted. The pore channels are irregularly accumulated in a spherical shape, which causes some turbulence to the gas flow; second, a large amount of organic matter exists in the calcination removal process, which easily causes the inactivation of the catalytically active components embedded in the extruded monolithic catalyst. Therefore, it is only limited to the preparation of the honeycomb carrier. Therefore, for the molecular sieve-based honeycomb monolithic denitration catalyst, an effective honeycomb structure manufacturing method is particularly important. SUMMARY

[0009] The purpose of the present application is to provide a preparation method and application of a molecular sieve-based honeycomb monolithic denitration catalyst, aiming to solve the problem of incomplete reaction contact of the molecular sieve catalyst embedded in the honeycomb monolithic catalyst, and the problem of difficulty in molding due to the inertness of the molecular sieve catalyst.

[0010] To achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0011] A preparation method of a molecular sieve-based honeycomb monolithic denitration catalyst, comprising the following steps:

[0012] (1) The molecular sieve-based catalyst and the metal-modified natural silicon-aluminum mineral are mixed uniformly, then an organic binder, a extrusion aid, a pore-forming agent and glass fiber are added, and finally a structure-making agent is added to obtain a mixed powder;

[0013] (2) The inorganic binder, the acid solution, the humectant and water are added to the mixed powder, and after being mixed thoroughly, the mixture is subjected to processes such as kneading, pugging, aging, pre-extrusion, extrusion molding, pre-drying, structure water, drying and calcination to obtain a molecular sieve-based honeycomb monolithic denitration catalyst.

[0014] Further, the molecular sieve-based catalyst contains one or more of ZSM-5 molecular sieve, ZSM-35 molecular sieve, SSZ-13 molecular sieve, SSZ-39 molecular sieve, SAPO-11 molecular sieve, SAPO-34 molecular sieve, SAPO-47 molecular sieve, Y-type molecular sieve, Beta molecular sieve, KFI-type molecular sieve, mordenite (MOR), and the molar ratio of silicon dioxide to aluminum oxide of the molecular sieve is 2-300:1.

[0015] Further, the metal element contained in the molecular sieve-based catalyst is one or more of iron, copper, manganese, cerium, lanthanum, rhodium, ruthenium, palladium, osmium, and the content of the metal element is 0.1-10.0wt%.

[0016] Preferably, the molecular sieve-based catalyst is one or more of FeCu-ZSM-5 molecular sieve, FeCu-SSZ-13 molecular sieve, FeCu-SAPO-34 molecular sieve.

[0017] Further, the natural silicon-aluminum mineral in the metal-modified natural silicon-aluminum mineral is one or more of rectorite, kaolin, feldspar, nepheline, leucite, epidote, muscovite, pyrophyllite, kaolinite, rectorite, hard jade, spodumene, diaspore, perlite, phlogopite, vermiculite, montmorillonite, talc, serpentine, illite, palygorskite, sepiolite, diatomite, attapulgite, enstatite, diopside, amphibole, olivine, and the content of impurities (substances other than aluminum oxide and silicon dioxide) of the natural silicon-aluminum mineral is less than 20wt%, and the particle size is not less than 200 mesh.

[0018] Further, the metal element in the metal-modified natural silicon-aluminum mineral is one or more of iron, copper, manganese, cerium, lanthanum, rhodium, ruthenium, palladium, osmium, tungsten, and the content of the metal is 0.1-10.0wt%, and the introduction method is to use nitrate or organic salt of the above metal to spray load or impregnate load on the natural silicon-aluminum mineral, and then the mixture is dried at 50-100℃ and crushed to obtain the metal-modified natural silicon-aluminum mineral with a particle size of not less than 200 mesh.

[0019] Further, the organic binder is one or more of sodium carboxymethyl cellulose, sodium polyacrylate, sodium hydroxypropyl cellulose, polyethylene glycol, polyethylene oxide, and phenol formaldehyde resin.

[0020] Further, the extrusion aid is one or more of starch, sesbania gum, ethanolamine, or sodium stearate.

[0021] Further, the glass fiber has a main length distribution of 1.0-10.0 mm.

[0022] Further, the structure manufacturing agent is a water-soluble high-molecular bundle fiber, including one or more of water-soluble polyvinyl alcohol fiber, water-soluble seaweed fiber, and water-soluble carboxymethyl cellulose fiber, and is required to be in a bundle shape, specifically, has a length of 0.2-3.0 mm and a diameter of 10-1000 μm, and the length is adjusted according to the thickness of the honeycomb wall to achieve the purpose of directly penetrating the inner wall.

[0023] Further, the pore-forming agent is a plant fiber particle, including one or more of straw, rice husk, sawdust, wood chips, and bamboo chips, and has a particle size of no less than 200 mesh.

[0024] Further, the inorganic binder is one or more of silica sol, water glass, pseudo-boehmite, and aluminum sol.

[0025] Further, the acid solution is an organic acid and inorganic acid solution, the organic acid includes one or more of citric acid, tartaric acid, malic acid, oxalic acid, and lactic acid, and the inorganic acid includes one or more of hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, and boric acid. The concentration of the organic acid aqueous solution and the inorganic acid aqueous solution is 5-20 wt%.

[0026] Further, the humectant is one or more of glycerol, tung oil, and peanut oil.

[0027] Further, the water is one or more of deionized water, pure water, and mineral water.

[0028] Further, the mass ratio of each raw material is: metal-modified natural silicon-aluminum mineral: molecular sieve-based catalyst: organic binder: extrusion aid: glass fiber: structure manufacturing agent: pore-forming agent: inorganic binder: organic acid: inorganic acid: humectant: water = 50-100: 1-35: 1-5: 1-8: 1-5: 10-50: 1-15: 3-8: 1-5: 1-5: 3-10: 10-25.

[0029] Further, the kneading is carried out after all raw materials are added, the mixing time is 10-60 min; the number of the dough refining is 2-3 times; the aging time is 1-10 days; the pre-extrusion is the trial extrusion after the die is replaced and the die lubrication, the pre-extrusion time is 5-30 min; the extrusion forming is the double screw rod type extrusion, which is matched with different shaped dies to carry out the extrusion forming, the wall thickness adjustment range is 0.5-3.0 mm; the pre-drying is the pre-removal of 5wt% moisture of the material; the drying mode is the temperature and humidity synergistic cross control method, namely, the humidity and temperature curves are controlled to cross and synergistically dry and dehydrate; the calcination mode adopts the low rate platform temperature rising method and is sealed calcined in a muffle furnace.

[0030] Further, the structured water solution is that the pre-dried material is soaked in water, the water solution temperature is adjusted according to the dissolution temperature of the structure manufacturing agent, and the temperature range is 20-90℃. The structured water solution time is required to be controlled in 0.5-2.0 h, and finally 2-3 times of water washing (water temperature 20-90℃) is carried out.

[0031] Preferably, the drying mode is: temperature and humidity synergistic cross control, temperature control 25-100℃, humidity control 5%-80%.

[0032] Preferably, in the drying process, the temperature is first controlled to be 25℃, the humidity is controlled to be 80%; then the temperature is controlled to be 40℃, the humidity is controlled to be 60%; then the temperature is controlled to be 60℃, the humidity is controlled to be 40%; then the temperature is controlled to be 80℃, the humidity is controlled to be 10%. This method can effectively control the drying rate and reduce cracking.

[0033] Preferably, the calcination mode is: the initial temperature is >80℃, the temperature is raised at a low rate of 0.5-2℃ / min, and the temperature range is 80-800℃.

[0034] Preferably, in the calcination process, a platform calcination glue removal is set at 180-400℃, and then the temperature is continuously raised to 550-800℃ for calcination for 6-8 h.

[0035] Compared with the prior art, the advantages of the present application are:

[0036] 1. It is crucial to select a suitable catalytic carrier and modify the carrier with metal. The present application utilizes the impregnation method to introduce relevant metal elements in one step, overcoming the complex process flow. The metal modified natural silicon-aluminum mineral not only serves as a catalytic carrier, supporting and strengthening the molecular sieve catalyst, but also interacts with the molecular sieve catalyst, promoting the reaction.

[0037] 2. For molecular sieve-based honeycomb integral denitrification catalysts, an effective honeycomb structure manufacturing method is particularly important. The present invention structurally adjusts the honeycomb integral catalyst, and uses structural agents such as water-soluble polymer bundle fibers to manufacture through-type regular channels to achieve the purpose of penetrating the inner wall, increase the reaction contact time between the reaction gas and the embedded molecular sieve catalyst, and improve the nitrogen oxide removal efficiency. The purpose of the water-soluble feature is to remove the structural manufacturing agent in a water-soluble manner and reduce the occurrence of carbon deposition and deactivation of the internal molecular sieve catalyst caused by organic matter during the high-temperature roasting stage. The present invention structurally adjusts the honeycomb integral denitrification catalyst on a macroscopic level to achieve direct through-connection of the honeycomb inner wall; on a microscopic level, the metal-modified natural silica-aluminum minerals can interact with the molecular sieve catalyst to promote the denitrification reaction; in the production and preparation process, natural silica-aluminum minerals play a vital role in the molding process and application.

[0038] 3. The molecular sieve-based honeycomb integral denitration catalyst prepared by the present invention has obvious advantages: compared with the traditional vanadium-based denitration catalyst, the present invention utilizes molecular sieve catalysts to replace the biotoxic vanadium species, making the integral denitration catalyst more green and environmentally friendly, and the addition of metal-modified molecular sieve catalysts can effectively improve the catalytic performance. Compared with inert carriers, metal-modified natural silica-aluminum minerals can not only enhance catalytic activity, but also ensure smoothness during extrusion molding. After roasting and molding, the mechanical strength of the integral catalyst is enhanced through the sintering change process. In addition, the introduction of water-soluble structure-making agents can structurally adjust the inner wall of the honeycomb, and create regular through-channels while ensuring that the molecular sieve catalyst does not become inactivated due to carbon deposition, thereby increasing the reaction contact time.

[0039] 4. During the denitration reaction, the metal-modified natural silica-alumina mineral interacts with the molecular sieve catalyst. The resulting denitration catalyst exhibits high adhesion, strong adsorption, and high reactivity, effectively overcoming the inherent weakness of molecular sieve catalysts, significantly improving extrusion fluidity and mechanical strength after molding. The method of the present invention offers a simple preparation process, low production costs, and ease of scalable production, promising promising industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Comparison of the honeycomb cross-section structure before and after manufacturing; left: before structuring; right: after structuring. DETAILED DESCRIPTION

[0041] The present invention will be further described below with reference to specific examples, which are intended to illustrate the embodiments and features of the present invention in detail and are not to be construed as limiting the present invention in any way.

[0042] like Figure 1As shown, the present invention makes adjustments to the honeycomb structure and adds a water-soluble structure-making agent, which not only reduces the carbon deposition poisoning phenomenon of the molecular sieve catalyst, but also realizes regular penetration of the inner wall, increases the internal catalyst contact time, and improves the catalytic efficiency.

[0043] The FeCu-ZSM-5, FeCu-SSZ-13 and FeCu-SAPO-34 molecular sieves in the embodiment are high-performance denitrification molecular sieves synthesized in situ by a one-pot method. They are bimetallic molecular sieve catalysts. The introduction of Cu can not only regulate the Fe 3+ and the acidity of molecular sieves, and can also improve their redox capacity and isolate Cu 2+ , higher framework Fe 3+ , good redox properties and acidity of the molecular sieve catalyst has good denitrification catalytic activity.

[0044] The natural silica-alumina mineral used in the embodiment is natural rectorite (purchased from Hubei Mingliu Rectorite Co., Ltd., with a particle size of less than 200 meshes). The content of SiO2 in the natural rectorite is 43.2%, and the content of Al2O3 is 37.2%.

[0045] The natural silica-alumina mineral kaolin in the embodiment (purchased from China Kaolin Company, with a particle size of less than 300 mesh) has a SiO2 content of 48.0% and an Al2O3 content of 37.0%.

[0046] Example 1

[0047] A method for preparing a molecular sieve-based honeycomb monolithic denitration catalyst for removing nitrogen oxides comprises the following steps:

[0048] The raw materials were weighed according to the following mass proportions: 45 parts of natural silica-alumina mineral rectorite, 40 parts of FeCu-ZSM-5 molecular sieve, 3 parts of sodium carboxymethyl cellulose, 5 parts of sesbania powder, 1 part of glass fiber (aspect ratio 2-4:1), 20 parts of water-soluble polyvinyl alcohol bundled fibers, 10 parts of sawdust, 7 parts of silica sol, 1 part of lactic acid, 1 part of nitric acid, 10 parts of glycerol, and 25 parts of deionized water.

[0049] Before mixing the materials, 45 parts of natural silica-aluminum mineral rectorite were metal modified. The specific process is as follows:

[0050] Take 45 parts of natural silica-alumina mineral rectorite, spray and impregnate it with 3 parts of manganese nitrate solution (1 mol / L) under stirring, and after drying and crushing, the total mass increases by about 1-2 wt%.

[0051] (1) Add metal-modified natural silica-alumina mineral rectorite and FeCu-ZSM-5 molecular sieve into a mixer and mix them evenly.

[0052] (2) Then sodium carboxymethyl cellulose, sesbania powder, glass fiber, wood chips are added into the mixing machine and mixed evenly to obtain uniform dry materials.

[0053] (3) Water-soluble polyvinyl alcohol bundle fibers are added and mixed evenly.

[0054] (4) Then silica sol, lactic acid, nitric acid, glycerol and deionized water are added and kneaded.

[0055] (5) The kneaded mud in step (4) is repeatedly kneaded 3 times.

[0056] (6) The mud in step (5) is sealed with plastic wrap and placed in a dry and cool place for aging for 48 hours.

[0057] (7) The kneaded mud in step (6) is placed into a molding machine and extruded into a honeycomb shape.

[0058] (8) The molded honeycomb is pre-dried to remove 5 wt% of the total mass of water, and the water-soluble polyvinyl alcohol bundle fibers are removed by soaking in 60°C water for 10 hours. After soaking, the material is rinsed with 60°C water for 3 times to obtain material A.

[0059] (9) Material A is dried with a drying curve of temperature 30°C, humidity 70%, drying time 10h; temperature 50°C, humidity 60%, drying time 5h; temperature 70°C, humidity 30%, drying time 3h; finally transferred to a general oven at 100°C for 3h to obtain material B.

[0060] (10) Material B is placed in a muffle furnace and calcined with a firing curve of 100°C starting temperature, controlled temperature increase of 0.5°C per minute, 2h of glue removal at 200°C, continued temperature increase to 400°C for 2h, and temperature increase to 600°C for 8h to obtain a molecular sieve-based honeycomb monolithic denitration catalyst.

[0061] (11) The prepared molecular sieve-based honeycomb monolithic denitration catalyst is placed in a monolithic catalyst evaluation device and evaluated in a simulated flue gas component N2, CO2, NH3, NO, O2 small sample. The space velocity is maintained at 5000h -1 , [NO] = [NH3] = 500ppm, [O2] = 5%, H2O = 5%, and the NO concentration at the inlet and outlet is detected respectively to calculate the denitration efficiency of the catalyst. The results are shown in Table 1.

[0062] Example 2

[0063] A method for preparing a molecular sieve-based honeycomb monolithic denitration catalyst for nitrogen oxide removal, comprising the following steps:

[0064] The raw materials are weighed according to the following mass ratio: 50 parts of natural silico-aluminate mineral kaolin, 35 parts of FeCu-ZSM-5 molecular sieve, 3 parts of sodium carboxymethyl cellulose, 5 parts of sesbania powder, 1 part of glass fiber (length-diameter ratio 2-4:1), 25 parts of water-soluble polyvinyl alcohol bundle fiber, 10 parts of rice hull powder, 4 parts of silica sol, 1 part of oxalic acid, 1 part of nitric acid, 5 parts of tung oil, and 16 parts of deionized water.

[0065] Before mixing the materials, 50 parts of natural silico-aluminate mineral kaolin is first subjected to metal modification, and the specific process is as follows:

[0066] Take 50 parts of natural silico-aluminate mineral kaolin, and spray load 3 parts of manganese nitrate solution (1 mol / L) while stirring. After drying and crushing, the total mass increases by about 1-2 wt%.

[0067] (1) The metal-modified natural silico-aluminate mineral kaolin and FeCu-ZSM-5 molecular sieve are added to a mixing machine and mixed uniformly.

[0068] (2) Then the sodium carboxymethyl cellulose, sesbania powder, glass fiber, and rice hull powder are added to the mixing machine and mixed uniformly to obtain a uniform dry material.

[0069] (3) The water-soluble polyvinyl alcohol bundle fiber is added and mixed uniformly.

[0070] (4) Then the silica sol, oxalic acid, nitric acid, tung oil, and deionized water are added and kneaded.

[0071] (5) The kneaded mud in step (4) is repeatedly kneaded 2 times.

[0072] (6) The mud in step (5) is sealed with plastic wrap and placed in a dry and cool place for aging for 48 hours.

[0073] (7) The kneaded mud in step (6) is placed in a molding machine and extruded into a honeycomb shape.

[0074] (8) The molded honeycomb is pre-dried to remove 5 wt% of water, then placed in 60°C water to remove the water-soluble polyvinyl alcohol bundle fiber, soaked for 10 hours, then taken out and rinsed with 60°C water for 3 times to obtain material A.

[0075] (9) Material A is dried, and the drying curve is as follows: temperature 30°C, humidity 60%, drying for 10 hours; temperature 50°C, humidity 60%, drying for 5 hours; temperature 70°C, humidity 30%, drying for 3 hours; finally transferred to a general oven at 100°C for 3 hours to obtain material B.

[0076] (10) Put the material B into the muffle furnace for calcination, and the firing curve is as follows: temperature rising from 100℃, temperature rising 0.5℃ per minute, degumming at 200℃ for 2h, temperature rising to 400℃ and keeping for 2h, temperature rising to 600℃ and keeping for 8h, to obtain the molecular sieve-based honeycomb monolithic denitration catalyst.

[0077] (11) Put the prepared molecular sieve-based honeycomb monolithic denitration catalyst into the monolithic catalyst evaluation device, simulate the flue gas components N2, NH3, H2O, NO, O2 for evaluation, keep the space velocity at 5000h -1 , [NO] = [NH3] = 500ppm, [O2] = 5%, H2O = 5%, respectively detect the NO concentration of the inlet and outlet, and calculate the denitration efficiency of the catalyst. The results are shown in Table 1.

[0078] Example 3

[0079] A preparation method of a molecular sieve-based honeycomb monolithic denitration catalyst for nitrogen oxide removal, comprising the following steps:

[0080] According to the following mass ratio, the raw materials are weighed: 55 parts of natural silicon-aluminum mineral palygorskite, 30 parts of FeCu-SSZ-13 molecular sieve, 3 parts of sodium carboxymethyl cellulose, 8 parts of sesbania powder, 1 part of glass fiber (aspect ratio 2-4:1), 25 parts of water-soluble polyvinyl alcohol bundle fiber, 10 parts of straw powder, 4 parts of pseudo-boehmite, 1 part of malic acid, 1 part of nitric acid, 7 parts of glycerol, and 17 parts of deionized water.

[0081] Before mixing the materials, the 55 parts of natural silicon-aluminum mineral palygorskite is first modified with metal, and the specific process is as follows:

[0082] Take 55 parts of natural silicon-aluminum mineral palygorskite, and load 3 parts of manganese nitrate solution (1 mol / L) by spraying while stirring. After drying and crushing, the total mass increases by about 1-2wt%.

[0083] (1) Put the natural silicon-aluminum mineral palygorskite and FeCu-SSZ-13 molecular sieve into the mixing machine and mix uniformly.

[0084] (2) Then add sodium carboxymethyl cellulose, sesbania powder, glass fiber, and straw powder into the mixing machine and mix to obtain uniform dry materials.

[0085] (3) Add water-soluble polyvinyl alcohol bundle fiber and mix uniformly.

[0086] (4) Then add pseudo-boehmite, malic acid, nitric acid, glycerol, and deionized water for kneading.

[0087] (5) Repeat the kneaded mud in step (4) for 2 times.

[0088] (6) The mud in step (5) is sealed with plastic wrap and placed in a dry and cool place for 24 hours.

[0089] (7) The mud in step (6) is placed in a molding machine and extruded into a honeycomb shape.

[0090] (8) The honeycomb is pre-dried to remove 5wt% of water, then placed in 60°C water to remove water-soluble polyvinyl alcohol fibers, soaked for 10 hours, then taken out and rinsed with 60°C water for 3 times to obtain material A.

[0091] (9) Material A is dried, and the drying curve is as follows: temperature 30°C, humidity 80%, drying for 10 hours; temperature 40°C, humidity 70%, drying for 5 hours; temperature 70°C, humidity 30%, drying for 3 hours; finally transferred to a general oven at 100°C for 3 hours to obtain material B.

[0092] (10) Material B is placed in a muffle furnace and calcined, and the calcination curve is as follows: start heating at 100°C, increase the temperature by 0.5°C per minute, calcine and remove glue for 2 hours at 170°C, continue to increase the temperature to 350°C for 2 hours, and then increase the temperature to 550°C for 8 hours to obtain a molecular sieve-based honeycomb monolithic denitration catalyst.

[0093] (11) The prepared new molecular sieve-based honeycomb monolithic denitration catalyst is placed in a monolithic catalyst evaluation device, and the components of the simulated flue gas N2, NH3, H2O, NO, O2 are maintained at a space velocity of 5000h -1 , [NO] = [NH3] = 500ppm, [O2] = 5%, H2O = 5%, the NO concentration at the inlet and outlet is detected respectively, and the denitration efficiency of the catalyst is calculated. The results are shown in Table 1.

[0094] Example 4

[0095] A preparation method of a molecular sieve-based honeycomb monolithic denitration catalyst for nitrogen oxide removal, comprising the following steps:

[0096] The raw materials are weighed according to the following mass ratio: 60 parts of natural silicon-aluminum mineral kaolin, 25 parts of FeCu-ZSM-5 molecular sieve, 3 parts of sodium carboxymethyl cellulose, 5 parts of sesbania powder, 1 part of glass fiber (aspect ratio 2-4:1), 25 parts of water-soluble polyvinyl alcohol fiber, 10 parts of sawdust, 4 parts of silica sol, 1 part of lactic acid, 1 part of nitric acid, 5 parts of glycerol, and 14 parts of deionized water.

[0097] Before mixing the materials, the 60 parts of natural silicon-aluminum mineral kaolin is first modified with metal, and the specific process is as follows:

[0098] Take 60 parts of natural silicon-aluminum mineral kaolin, and load 3 parts of molybdenum nitrate solution (1 mol / L) while stirring, then dry and crush to increase the total mass by about 1-2wt%.

[0099] (1) The metal-modified natural silica-alumina mineral kaolin, FeCu-ZSM-5 molecular sieve is added into a mixer and mixed evenly.

[0100] (2) The sodium carboxymethyl cellulose, sesbania powder, glass fiber, sawdust is added into the mixer and mixed evenly to obtain a uniform dry material.

[0101] (3) The water-soluble polyvinyl alcohol bundle fibers are added and mixed evenly.

[0102] (4) Then the silica sol, lactic acid, nitric acid, glycerol and deionized water are added and kneaded.

[0103] (5) The kneaded mud in step (4) is repeatedly milled 2 times.

[0104] (6) The mud in step (5) is sealed with a plastic wrap and placed in a dry and cool place for aging for 48 h.

[0105] (7) The milled mud in step (6) is placed into a molding machine and extruded into a honeycomb shape.

[0106] (8) The molded honeycomb is pre-dried to remove 5 wt% of water, and then placed in a 50°C water bath to remove the water-soluble polyvinyl alcohol bundle fibers. After soaking for 10 hours, it is taken out and rinsed with 60°C water for 3 times to obtain material A.

[0107] (9) The material A is dried with a drying curve of temperature 30°C, humidity 80%, drying for 10 h; temperature 50°C, humidity 60%, drying for 5 h; temperature 70°C, humidity 30%, drying for 3 h; finally transferred to an oven at 100°C for 3 h to obtain material B.

[0108] (10) The material B is placed in a muffle furnace and calcined with a firing curve of starting temperature 100°C, temperature increasing by 0.5°C per minute, calcining and removing glue for 2 h at 230°C, continuing to heat to 420°C for 2 h, and heating to 650°C for 8 h to obtain a molecular sieve-based honeycomb monolithic denitration catalyst.

[0109] (11) The prepared molecular sieve-based honeycomb monolithic denitration catalyst is placed in a monolithic catalyst evaluation device, and the components of the simulated flue gas N2, NH3, H2O, NO, O2 are maintained at a space velocity of 5000 h -1 , [NO] = [NH3] = 500 ppm, [O2] = 5%, H2O = 5%, and the NO concentration at the inlet and outlet is detected respectively to calculate the denitration efficiency of the catalyst. The results are shown in Table 1.

[0110] Example 5

[0111] A preparation method of a molecular sieve-based honeycomb monolithic denitration catalyst for nitrogen oxide removal, comprising the following steps:

[0112] Each raw material is weighed according to the following mass ratio: 70 parts of natural silicon-aluminum mineral kaolin, 15 parts of FeCu-SSZ-13 molecular sieve, 3 parts of sodium carboxymethyl cellulose, 7 parts of sesbania powder, 1 part of glass fiber (aspect ratio 2-4:1), 25 parts of water-soluble polyvinyl alcohol bundle fiber, 10 parts of bamboo chips, 5 parts of aluminum sol, 2 parts of citric acid, 1 part of boric acid, 7 parts of glycerol, and 18 parts of deionized water.

[0113] Before mixing the materials, the 70 parts of natural silicon-aluminum mineral kaolin is first subjected to metal modification, and the specific process is as follows:

[0114] Take 70 parts of natural silicon-aluminum mineral kaolin, and load 5 parts of molybdenum nitrate solution (1 mol / L) by spraying while stirring. After drying and crushing, the total mass increases by about 1-2 wt%.

[0115] (1) The metal-modified natural silicon-aluminum mineral kaolin and FeCu-ZSM-5 molecular sieve are added to a mixing machine and mixed uniformly.

[0116] (2) Then the sodium carboxymethyl cellulose, sesbania powder, glass fiber, and bamboo chips are added to the mixing machine and mixed to obtain a uniform dry material.

[0117] (3) Add water-soluble polyvinyl alcohol bundle fiber and mix uniformly.

[0118] (4) Then add aluminum sol, citric acid, boric acid, glycerol, and deionized water and knead.

[0119] (5) Repeat the kneaded mud in step (4) for 3 times.

[0120] (6) Seal the mud in step (5) with plastic wrap and place it in a dry and cool place for 24 hours.

[0121] (7) Put the well-kneaded mud in step (6) into a molding machine and extrude it into a honeycomb shape.

[0122] (8) After pre-drying the molded honeycomb to remove 5 wt% of water, immerse it in 60°C water to remove the water-soluble polyvinyl alcohol bundle fiber. After soaking for 10 hours, take it out and rinse it with 60°C water for 3 times to obtain material A.

[0123] (9) Dry material A, and the drying curve is as follows: temperature 25°C, humidity 70%, drying for 8h; temperature 45°C, humidity 50%, drying for 8h; temperature 70°C, humidity 30%, drying for 4h; finally transfer to a general oven at 100°C for 2h to obtain material B.

[0124] (10) Put the material B into the muffle furnace for calcination, and the firing curve is as follows: start to increase the temperature at 100℃, increase the temperature by 1.0℃ per minute, calcine and remove the glue at 180℃ for 2h, continue to increase the temperature to 370℃ and keep for 2h, and then increase the temperature to 550℃ and keep for 8h, to obtain the molecular sieve-based honeycomb monolithic denitration catalyst.

[0125] (11) Put the prepared molecular sieve-based honeycomb monolithic catalyst into the monolithic catalyst evaluation device, simulate the flue gas components N2, NH3, H2O, NO, O2, keep the space velocity at 5000h-1, [NO] = [NH3] = 500ppm, [O2] = 5%, H2O = 5%, respectively detect the NO concentration at the inlet and outlet, and calculate the denitration efficiency of the catalyst. The results are shown in Table 1. -1

[0126] Example 6

[0127] A preparation method of a molecular sieve honeycomb monolithic catalyst for nitrogen oxide removal, comprising the following steps:

[0128] The raw materials are weighed according to the following mass ratio: natural silicon-aluminum mineral kaolin 75 parts, FeCu-SAPO-34 molecular sieve 10 parts, sodium carboxymethyl cellulose 3 parts, sesbania powder 5 parts, glass fiber (aspect ratio 2-4:1) 1 part, water-soluble polyvinyl alcohol bundle fiber 30 parts, wood chips 10 parts, silica sol 4 parts, lactic acid 1 part, nitric acid 1 part, glycerol 5 parts, and deionized water 16 parts.

[0129] Before mixing the materials, the 75 parts of natural silicon-aluminum mineral kaolin is first subjected to metal modification, and the specific process is as follows:

[0130] Take 75 parts of natural silicon-aluminum mineral kaolin, and load 5 parts of manganese nitrate solution (1 mol / L) by spraying while stirring. After drying and crushing, the total mass increases by about 1-2wt%.

[0131] (1) Put the metal-modified natural silicon-aluminum mineral kaolin and FeCu-ZSM-5 molecular sieve into the mixing machine and mix uniformly.

[0132] (2) Then add sodium carboxymethyl cellulose, sesbania powder, glass fiber, and wood chips into the mixing machine and mix uniformly to obtain a uniform dry material.

[0133] (3) Add water-soluble polyvinyl alcohol bundle fiber and mix uniformly.

[0134] (4) Then add silica sol, lactic acid, nitric acid, glycerol, and deionized water for kneading.

[0135] (5) Repeat the kneaded mud in step (4) for 3 times.

[0136] ​(6) The clay in step (5) is sealed with plastic wrap and placed in a dry and cool place for 48 hours.

[0137] (7) The clay in step (6) is placed in a molding machine and extruded into a honeycomb shape.

[0138] (8) The honeycomb is pre-dried to remove 5wt% of water, then soaked in 60°C water for 10 hours to remove water-soluble polyvinyl alcohol fibers, and then rinsed with 60°C water for 3 times to obtain material A.

[0139] (9) Material A is dried with a drying curve of temperature 30°C, humidity 80%, drying for 10 hours; temperature 50°C, humidity 60%, drying for 5 hours; temperature 70°C, humidity 30%, drying for 3 hours; and finally transferred to a general oven at 100°C for 3 hours to obtain material B.

[0140] (10) Material B is placed in a muffle furnace and calcined with a firing curve of 100°C, increasing by 0.5°C per minute, 200°C for 2 hours to remove glue, 400°C for 2 hours, and 600°C for 8 hours to obtain a molecular sieve-based honeycomb monolithic denitration catalyst.

[0141] (11) The prepared molecular sieve-based honeycomb monolithic denitration catalyst is placed in a monolithic catalyst evaluation device, and the components of the flue gas N2, NH3, H2O, NO, and O2 are simulated, with a space velocity of 5000h -1 , [NO] = [NH3] = 500ppm, [O2] = 5%, H2O = 5%, and the NO concentration at the inlet and outlet is detected respectively to calculate the denitration efficiency of the catalyst. The results are shown in Table 1.

[0142] Example 7

[0143] A method for preparing a molecular sieve-based honeycomb monolithic denitration catalyst for nitrogen oxide removal, comprising the following steps:

[0144] The raw materials are weighed according to the following mass ratio: 80 parts of natural silicon-aluminum mineral kaolin, 15 parts of FeCu-SAPO-34 molecular sieve, 3 parts of sodium carboxymethyl cellulose, 5 parts of sesbania powder, 1 part of glass fiber (aspect ratio 2-4:1), 30 parts of water-soluble polyvinyl alcohol fiber, 10 parts of wood chips, 4 parts of silica sol, 1 part of citric acid, 0.5 parts of sulfuric acid, 5 parts of glycerol, and 14 parts of deionized water.

[0145] Before mixing the materials, the 80 parts of natural silicon-aluminum mineral kaolin is modified with metal, and the specific process is as follows:

[0146] Take 80 parts of natural silica-alumina mineral kaolin, while stirring, spray load 5 parts of manganese nitrate solution (1 mol / L), dry and crush, the total mass increases about 1-2 wt%.

[0147] (1) The metal-modified natural silica-alumina mineral kaolin, FeCu-ZSM-5 molecular sieve is added into the mixer and mixed uniformly.

[0148] (2) Then sodium carboxymethyl cellulose, sesbania powder, glass fiber, wood chips are added into the mixer and mixed to obtain uniform dry material.

[0149] (3) Water-soluble polyvinyl alcohol fibrous is added and mixed uniformly.

[0150] (4) Then silica sol, lactic acid, nitric acid, glycerol and deionized water are added and kneaded.

[0151] (5) The kneaded mud in step (4) is repeatedly milled 2-3 times.

[0152] (6) The mud in step (5) is sealed with plastic wrap and placed in a dry and cool place for aging for 48 h.

[0153] (7) The milled mud in step (6) is put into the molding machine and extruded into a honeycomb shape.

[0154] (8) The molded honeycomb is pre-dried to remove 5 wt% of water, then put into a 60℃ water bath to remove water-soluble polyvinyl alcohol fibrous, soaked for 10 hours, then taken out and rinsed with 60℃ water for 3 times to obtain material A.

[0155] (9) Material A is dried, the drying curve is: temperature 30℃, humidity 80%, drying for 10h; temperature 50℃, humidity 60%, drying for 5h; temperature 70℃, humidity 30%, drying for 3h; finally transferred to a general oven at 100℃ for 3h, to obtain material B.

[0156] (10) Material B is put into a muffle furnace and calcined, the calcination curve is: start heating at 100℃, increase the temperature by 0.5℃ per minute, heat to 250℃ for 2h to remove glue, continue to heat to 450℃ for 2h, then heat to 700℃ and keep for 8h, to obtain the molecular sieve-based honeycomb monolithic denitration catalyst.

[0157] (11) The prepared molecular sieve-based honeycomb monolithic denitration catalyst is put into a monolithic catalyst evaluation device, simulating the components of flue gas N2, NH3, H2O, NO, O2, keeping the space velocity at 5000h -1 , [NO] = [NH3] = 500ppm, [O2] = 5%, H2O = 5%, respectively detecting the NO concentration of inlet and outlet, calculating the denitration efficiency of the catalyst. The results are shown in Table 1.

[0158] The results of the denitration reaction evaluation of examples 1-7 are shown in Table 1.

[0159] Table 1 Denitration reaction evaluation results

[0160]

[0161]

[0162] Through experimental demonstration, the application selects a suitable natural silicon-aluminum mineral carrier, overcomes the difficulty that a pure molecular sieve catalyst is not easy to be formed, improves the smoothness of the extrusion process and the mechanical strength after calcination, and the metal-modified natural silicon-aluminum mineral carrier can provide certain catalytic activity. The application adjusts the structure of the honeycomb body, and the water-soluble high-molecular bundle-shaped fiber effectively manufactures a regular inner wall through structure, exposes the internal embedded molecular sieve catalyst, and protects the catalyst from the influence of carbon deposition poisoning by using the water-soluble property. Compared with a traditional commercial V-based honeycomb monolithic catalyst, the application uses a molecular sieve catalyst as a main active component to manufacture an internally-through honeycomb monolithic catalyst, implements the green environmental protection concept, and has practical application value.

Claims

1. A method for preparing a molecular sieve-based honeycomb monolithic denitrification catalyst, characterized in that: The following steps are involved: (1) After uniformly mixing the molecular sieve-based catalyst and the metal-modified natural silica-aluminum mineral, an organic binder, an extrusion aid, a pore-forming agent, and glass fiber are added, and finally a structure-forming agent is added to obtain a mixed powder; The metal elements in the metal-modified natural silica-aluminum mineral are one or more of iron, copper, manganese, cerium, lanthanum, rhodium, ruthenium, palladium, osmium, and tungsten, and the metal content is 0.1 to 10.0 wt %. The introduction method is to use nitrates or organic salts of the above metals to spray load or impregnate the natural silica-aluminum mineral; The structure-making agent is a water-soluble polymer bundle fiber; (2) adding an inorganic binder, an acid solution, a moisturizing agent, and water to the mixed powder, and after thorough mixing, kneading, slurrying, aging, extrusion molding, pre-drying, structured water dissolution, drying, and calcining to obtain a molecular sieve-based honeycomb monolithic denitrification catalyst; Among them, the structured water-soluble material is soaked in water at 20~90 ℃ for 0.5~2.0 h, and then rinsed with water at 20~90 ℃ for 2~3 times.

2. The method for preparing a molecular sieve-based honeycomb monolithic denitration catalyst according to claim 1, wherein: The molecular sieve-based catalyst contains one or more of ZSM-5 molecular sieve, ZSM-35 molecular sieve, SSZ-13 molecular sieve, SSZ-39 molecular sieve, SAPO-11 molecular sieve, SAPO-34 molecular sieve, SAPO-47 molecular sieve, Y-type molecular sieve, Beta molecular sieve, KFI type molecular sieve, and mordenite, and the molar ratio of silica to alumina of the molecular sieve is 2~300:1; the metal element contained in the molecular sieve-based catalyst is one or more of iron, copper, manganese, cerium, lanthanum, rhodium, ruthenium, palladium, and osmium, and the content of the metal element is 0.1~10.0 wt%.

3. The method for preparing a molecular sieve-based honeycomb monolithic denitration catalyst according to claim 2, characterized in that: The molecular sieve-based catalyst is one or more of FeCu-ZSM-5 molecular sieve, FeCu-SSZ-13 molecular sieve, and FeCu-SAPO-34 molecular sieve.

4. The method for preparing a molecular sieve-based honeycomb monolithic denitration catalyst according to claim 1, characterized in that: The water-soluble polymer bundle fibers are one or more of polyvinyl alcohol fibers, seaweed fibers, and carboxymethyl cellulose fibers.

5. The method for preparing a molecular sieve-based honeycomb monolithic denitration catalyst according to claim 1, wherein: The natural silica-aluminum mineral in the metal-modified natural silica-aluminum mineral is one or more of rectorite, kaolin, feldspar, nepheline, leucite, beryl, muscovite, pyrophyllite, kaolinite, rectorite, jadeite, spodumene, diaspore, perlite, phlogopite, vermiculite, montmorillonite, talc, serpentine, illite, palygorskite, sepiolite, diatomite, attapulgite, enstatite, diopside, amphibole, and olivine, wherein the impurity content of the natural silica-aluminum mineral is less than 20 wt%, and the particle size is not less than 200 mesh; The organic binder is one or more of sodium carboxymethyl cellulose, sodium polyacrylate, sodium hydroxypropyl cellulose, polyethylene glycol, polyethylene oxide, and phenolic resin; The extrusion aid is one or more of starch, sesbania powder, ethanolamine or sodium stearate; The pore-forming agent is plant fiber particles, and the plant fiber is one or more of straw, rice husk, sawdust, wood chips, and bamboo chips; The inorganic binder is one or more of silica sol, water glass, pseudo-boehmite or alumina sol; The moisturizing agent is one or more of glycerin, tung oil and peanut oil.

6. The method for preparing a molecular sieve-based honeycomb monolithic denitration catalyst according to claim 1, wherein: The acid solution is an organic acid and an inorganic acid solution, the organic acid is one or more of citric acid, tartaric acid, malic acid, oxalic acid, and lactic acid; the inorganic acid is one or more of hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, and boric acid, and the concentrations of the organic acid aqueous solution and the inorganic acid aqueous solution are both 5-20 wt%.

7. The method for preparing a molecular sieve-based honeycomb monolithic denitration catalyst according to claim 6, characterized in that: The mass ratio of each raw material is: metal-modified natural silica-alumina mineral: molecular sieve-based catalyst: organic binder: extrusion aid: glass fiber: structure-making agent: pore-forming agent: inorganic binder: organic acid: inorganic acid: humectant: water = 50~100:1~35:1~5:1~8:1~5:10~50:1~15:3~8:1~5:1~5:3~10:10~25.

8. The method for preparing a molecular sieve-based honeycomb monolithic denitration catalyst according to claim 1, wherein: The kneading is to mix all the raw materials and then stir them, and the mixing time is 10 to 60 minutes; The number of times of kneading the mud is 2 to 3 times; The aging time is 1 to 10 days; The extrusion molding is a twin-screw extrusion, which is carried out with molds of different shapes, and the wall thickness can be adjusted within a range of 0.5 to 3.0 mm. The pre-drying is to remove 5 wt% of the water in the material after extrusion molding; The drying method is a temperature and humidity coordinated cross control method, that is, the humidity and temperature curves are controlled to cross and coordinate drying and dehydration; the calcination method adopts a low-rate platform heating method and calcination is carried out in a closed muffle furnace.

9. The method for preparing a molecular sieve-based honeycomb monolithic denitration catalyst according to claim 1, wherein: The drying method is: adopting temperature and humidity coordinated cross control, with the temperature controlled at 25~100℃ and the humidity controlled at 5%~80%; The calcination method is as follows: the starting temperature of the sintering curve is greater than 80°C, then the temperature is increased at a rate of 0.5-2°C / min, and when the temperature reaches 180-400°C, debinding is performed for 2 hours, and then the temperature is continued to be increased to 550-800°C and calcined for 6-8 hours.

10. Use of the molecular sieve-based honeycomb monolithic denitration catalyst prepared according to the preparation method according to any one of claims 1 to 9 in an NH3-SCR reaction.

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