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

Abstract

The invention discloses a preparation method and application of a molecular sieve-based honeycomb monolithic denitration catalyst. A molecular sieve-based catalyst, a metal-modified natural silicon-aluminum mineral, an organic binder, an extrusion aid, a pore forming agent, glass fibers, a structure manufacturing agent, an inorganic binder, an acid solution, a humectant and water are mixed, and the molecular sieve-based honeycomb-shaped integral denitration catalyst is obtained through the processes of structured water dissolution and the like. The water-soluble polymer bunchy fiber is used as a structure manufacturing agent, the negative influence of carbon deposition poisoning of a molecular sieve catalyst is reduced, honeycomb inner wall through connection is achieved, and a honeycomb-based multi-channel inner wall is built; and the contact area and the reaction contact time of the reaction gas and the molecular sieve catalyst embedded in the inner wall and the metal modified natural silicon-aluminum mineral are increased. The prepared denitration catalyst has high cohesiveness, strong adsorbability and high reaction activity, can effectively overcome the barren defect of a molecular sieve catalyst, and remarkably improves the extrusion smoothness and the mechanical strength after molding.

Description

Technical Field

[0001] The invention belongs to the technical field of nitrogen oxide removal, and specifically relates to a preparation method and application of a molecular sieve-based honeycomb integral denitration catalyst. Background Art

[0002] Nitrogen oxides (NO x ) is one of the main air pollutants, which is extremely harmful to human body, environment and even social economy. Among the many denitrification 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 traditional vanadium-tungsten-titanium catalysts is biologically toxic and environmentally harmful. The current regulatory standards have more stringent requirements for denitrification catalysts, requiring the use of efficient, pollution-free and safe new catalysts to replace vanadium-based catalysts. Molecular sieve catalysts have the characteristics of special pore structure, adjustable acidity and excellent hydrothermal stability. They have good catalytic activity in the removal of nitrogen oxides and have therefore attracted widespread attention from researchers.

[0004] In actual denitrification applications, the complex working conditions require that the integral catalyst must have a certain mechanical strength while exerting its catalytic effect. Therefore, extruded integral denitrification catalysts are required in industry.

[0005] Patent applications US 5248643 and US 5492883 use molecular sieve-based catalysts and related adhesives to prepare honeycomb monolithic catalysts through co-extrusion technology. However, the main body of the prepared monolithic catalyst is molecular sieve, and the preparation cost is relatively high, 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, adds some binder to overcome molding difficulties, 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 extrusion, and the results show good catalytic activity. Similarly, patent application CN 108273544 also confirms that the copper-iron mixed molecular sieve is mixed with related additives for extrusion, and NO is released in the temperature range of 200-550°C. x The conversion rate is greater than 80%. The above technology shows that molecular sieve catalysts have good application prospects for denitration reactions, but they still face certain challenges in large-scale application. First, molecular sieve catalysts are difficult to form due to their 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 catalytic carrier using natural minerals, binders and water. This technology lacks catalytically active components and is difficult to apply directly. Patent application CN 117839674A introduces a method of modifying kaolin and introducing metals into a kaolin carrier using an ion exchange method to obtain a denitrification catalyst that is resistant to poisoning. However, its process is relatively complicated and produces a lot of industrial wastewater, making it difficult to apply on a large scale industrially. Therefore, it is crucial to select a suitable catalytic carrier and modify the carrier with metals.

[0008] Due to its straight-through wall characteristics, the residence time of the reaction gas flow in the honeycomb extrusion-molded monolithic catalyst is short and it is difficult to form turbulence, 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, it is necessary to add a pore-forming agent for pore expansion. Most studies use organic media to form pores after roasting, adding a large amount of pore-forming agents to form irregular particle channels connected to each other. Patent application CN 108883356A uses starch-based pore-forming agents to form cross-pores with spherical particle stacking arrangements. Patent application CN 108727057 A uses cassava starch, corn stalk powder, etc. as pore-forming agents to effectively widen the channels and produce silicon nitride ceramic carriers. Patent application CN 102861595 A uses pulp cotton and the like as structural additives to enhance the mechanical strength and porosity of the monolithic catalyst. This type of technology faces two challenges: First, it only adjusts the microscopic porosity of the honeycomb without making macroscopic structural adjustments to the honeycomb. The pores are irregularly stacked in a spherical shape, which creates certain disturbances in the gas flow. Second, there is carbon deposition during the roasting and removal of a large amount of organic matter. For the extruded monolithic catalyst, the catalytically active components embedded therein are easily deactivated, so it is limited to the preparation of the honeycomb carrier. Therefore, for the molecular sieve-based honeycomb monolithic denitrification catalyst, an effective honeycomb structure manufacturing method is particularly important. Summary of the invention

[0009] The purpose of the present invention is to provide a method for preparing a molecular sieve-based honeycomb monolithic deNOx catalyst and its application, aiming to solve the problem of incomplete reaction contact of the molecular sieve catalyst embedded inside the honeycomb monolithic catalyst, and at the same time solve the problem of difficult molding due to the lean nature of the molecular sieve catalyst.

[0010] To achieve the above object, the present invention adopts the following technical solutions:

[0011] A method for preparing a molecular sieve-based honeycomb monolithic denitration catalyst comprises the following steps:

[0012] (1) After uniformly mixing the molecular sieve-based catalyst and the metal-modified natural silica-alumina 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;

[0013] (2) Adding an inorganic binder, an acid solution, a moisturizer and water to the above mixed powder, after being fully mixed, the mixed powder is subjected to the processes of kneading, slurry preparation, aging, pre-extrusion, extrusion molding, pre-drying, structured water dissolution, drying and calcination to obtain a molecular sieve-based honeycomb monolithic denitrification catalyst.

[0014] Furthermore, the molecular sieve contained in the molecular sieve-based catalyst is 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 (MOR), and the molar ratio of silicon dioxide to aluminum oxide of the molecular sieve is 2 to 300:1.

[0015] Furthermore, 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 to 10.0 wt%.

[0016] Preferably, 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.

[0017] Furthermore, the natural silica-aluminum minerals in the metal-modified natural silica-aluminum minerals are 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, diatomaceous earth, attapulgite, enstatite, diopside, amphibole, and olivine, wherein the impurity content (substances other than alumina and silica) of the natural silica-aluminum minerals is less than 20wt%, and the particle size is not less than 200 mesh.

[0018] Furthermore, 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, dry it at 50 to 100°C, and then crush it, with the particle size required to be not less than 200 meshes, to obtain the metal-modified natural silica-aluminum mineral.

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

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

[0021] Furthermore, the main length distribution of the glass fiber is 1.0 to 10.0 mm.

[0022] Furthermore, the structure manufacturing agent is a water-soluble polymer bundle fiber, including one or more of water-soluble polyvinyl alcohol fiber, water-soluble seaweed fiber, and water-soluble carboxymethyl cellulose fiber, which is required to be in the form of strips. Specifically, the length is required to be 0.2mm~3.0mm, and the diameter is required to be 10μm~1000μm. The length is adjusted according to the thickness of the honeycomb wall to achieve the purpose of directly penetrating the inner wall.

[0023] Furthermore, the pore-forming agent is plant fiber particles, including one or more of straw, rice husk, sawdust, wood chips, and bamboo chips, with a particle size of not less than 200 meshes.

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

[0025] Furthermore, the acid solution is an organic acid and an inorganic acid solution, wherein 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 concentrations of the organic acid aqueous solution and the inorganic acid aqueous solution are both 5 to 20 wt%.

[0026] Furthermore, the moisturizing agent is one or more of glycerin, tung oil, and peanut oil.

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

[0028] Furthermore, 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 manufacturing agent: pore former: 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] Furthermore, the kneading is to stir after all the raw materials are added, and the mixing time is 10 to 60 minutes; the number of times of mud kneading is 2 to 3 times; the aging time is 1 to 10 days; the pre-extrusion is the trial extrusion and mold lubrication after the mold is replaced, and the pre-extrusion time is 5 to 30 minutes; the extrusion molding is a double-screw extrusion, which is carried out in conjunction with molds of different shapes, and the wall thickness adjustment range is 0.5 to 3.0 mm; the pre-drying is to pre-remove 5wt% of the moisture of the material; 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 closed in a muffle furnace.

[0030] Furthermore, the structured water-soluble material is soaked in water after pre-drying, and the water-soluble temperature is adjusted according to the dissolution temperature of the structure-making agent, and the temperature range is 20-90° C. The structured water-soluble time is required to be controlled within 0.5-2.0 hours, and finally washed with water 2-3 times (water temperature 20-90° C.).

[0031] Preferably, the drying method is: coordinated cross-control of temperature and humidity, the temperature is controlled at 25-100° C., and the humidity is controlled at 5%-80%.

[0032] Preferably, during the drying process, the temperature is first controlled at 25°C and the humidity is controlled at 80%; then the temperature is controlled at 40°C and the humidity is controlled at 60%; then the temperature is controlled at 60°C and the humidity is controlled at 40%; then the temperature is controlled at 80°C and the humidity is controlled at 10%. This method can effectively control the drying rate and reduce cracking.

[0033] Preferably, the calcination method is: the starting temperature is >80°C, the temperature is increased at a low rate of 0.5-2°C / min, and the temperature range is 80-800°C.

[0034] Preferably, during the calcination process, a platform is set at 180-400° C. for calcination and debinding, and then the temperature is continued to be raised to 550-800° C. for calcination for 6-8 hours.

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

[0036] 1. It is very important to select a suitable catalytic carrier and modify the carrier with metal. The technology of the present invention uses the impregnation method to introduce the 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, plays a supporting and strengthening role for the molecular sieve catalyst, but also can interact with the molecular sieve catalyst to promote 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 removal efficiency of nitrogen oxides. The water-soluble characteristic is intended 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 uses molecular sieve catalysts to replace the biologically toxic 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 silicon-aluminum minerals can not only enhance the catalytic activity, but also ensure smoothness during extrusion molding. After roasting and molding, the mechanical strength of the integral catalyst is improved through the sintering change process. In addition, the introduction of a water-soluble structure manufacturing agent can structurally adjust the inner wall of the honeycomb, and manufacture regular through-channels while ensuring that the molecular sieve catalyst is not inactivated by carbon deposition, thereby increasing the reaction contact time.

[0039] 4. In the denitration reaction process, the metal-modified natural silicon-aluminum mineral can interact with the molecular sieve catalyst. The prepared denitration catalyst has high adhesion, strong adsorption and high reactivity, which can effectively overcome the poor quality of the molecular sieve catalyst and significantly improve the extrusion smoothness and mechanical strength after molding. The method of the present invention has a simple preparation process, low production cost, easy large-scale production, and good industrial application prospects. 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 is further described below in conjunction with specific examples, which are intended to illustrate the implementation scheme and features of the present invention in detail and should not be construed as any limitation of the present invention.

[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 examples are high-performance denitrification molecular sieves synthesized in situ by a one-pot method, and belong to 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 ability 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 meshes) 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 bundle 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-alumina mineral rectorite were first 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 and sawdust are added into a mixer and mixed evenly to obtain a uniform dry material.

[0053] (3) Add water-soluble polyvinyl alcohol fiber bundles and mix well.

[0054] (4) Then, add silica sol, lactic acid, nitric acid, glycerin and deionized water and knead.

[0055] (5) Repeat the kneading of the clay material in step (4) for 3 times.

[0056] (6) Seal the mud material in step (5) with plastic wrap and place it in a dry and cool place for aging for 48 hours.

[0057] (7) The clay prepared in step (6) is placed in a molding machine for extrusion molding.

[0058] (8) The formed honeycomb was pre-dried to remove 5 wt% of the total mass of water, and then placed in 60°C water to remove the water-soluble polyvinyl alcohol fiber bundles. After soaking for 10 hours, the honeycomb was taken out and rinsed with 60°C water for 3 times to obtain material A.

[0059] (9) Material A is dried, and its drying curve is as follows: temperature 30°C, humidity 70%, drying for 10 h; temperature 50°C, humidity 60%, drying for 5 h; temperature 70°C, humidity 30%, drying for 3 h; finally, it is transferred to a common oven at 100°C and dried for 3 h to obtain material B.

[0060] (10) Material B is placed in a muffle furnace for calcination. The sintering curve is as follows: the temperature is raised from 100°C, the temperature is raised by 0.5°C per minute, the temperature is raised to 200°C for debinding for 2 hours, the temperature is further raised to 400°C and maintained for 2 hours, and the temperature is further raised to 600°C and maintained for 8 hours to obtain a molecular sieve-based honeycomb integral denitrification catalyst.

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

[0062] Example 2

[0063] A method for preparing a molecular sieve-based honeycomb monolithic denitration catalyst for removing nitrogen oxides comprises the following steps:

[0064] The raw materials were weighed according to the following mass proportions: 50 parts of natural silica-alumina 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 (aspect ratio 2-4:1), 25 parts of water-soluble polyvinyl alcohol bundle fibers, 10 parts of rice husk 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 silica-alumina mineral kaolin are first metal-modified. The specific process is as follows:

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

[0067] (1) Add metal-modified natural silica-alumina mineral kaolin and FeCu-ZSM-5 molecular sieve into a mixer and mix them evenly.

[0068] (2) Then, sodium carboxymethyl cellulose, sesbania powder, glass fiber, and rice husk powder are added into a mixer and mixed evenly to obtain a uniform dry material.

[0069] (3) Add water-soluble polyvinyl alcohol fiber bundles and mix well.

[0070] (4) Then add silica sol, oxalic acid, nitric acid, tung oil and deionized water and knead.

[0071] (5) Repeat the kneading of the clay material in step (4) for 2 times.

[0072] (6) Seal the mud material in step (5) with plastic wrap and place it in a dry and cool place for aging for 48 hours.

[0073] (7) The clay prepared in step (6) is placed in a molding machine for extrusion molding.

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

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

[0076] (10) Material B was placed in a muffle furnace and calcined. The sintering curve was as follows: the temperature was increased from 100°C at a rate of 0.5°C per minute, the temperature was increased to 200°C for debinding for 2 h, the temperature was increased to 400°C and maintained for 2 h, and the temperature was increased to 600°C and maintained for 8 h to obtain a molecular sieve-based honeycomb integral denitrification catalyst.

[0077] (11) The prepared molecular sieve-based honeycomb monolithic denitrification catalyst was placed in the monolithic catalyst evaluation device to simulate the flue gas components N2, NH3, H2O, NO, and O2 for evaluation, maintaining the air velocity at 5000 h -1 , [NO] = [NH3] = 500ppm, [O2] = 5%, H2O = 5%, the NO concentrations at the inlet and outlet were detected respectively, and the denitration efficiency of the catalyst was calculated. The results are shown in Table 1.

[0078] Example 3

[0079] A method for preparing a molecular sieve-based honeycomb monolithic denitration catalyst for removing nitrogen oxides comprises the following steps:

[0080] The raw materials were weighed according to the following mass proportions: 55 parts of natural silica-alumina mineral rectorite, 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 bundled fibers, 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, 55 parts of natural silica-alumina mineral rectorite were first metal-modified. The specific process is as follows:

[0082] Take 55 parts of natural silica-alumina mineral rectorite, spray and load 3 parts of manganese nitrate solution (1 mol / L) while stirring, and after drying and crushing, the total mass increases by about 1-2 wt%.

[0083] (1) Add natural silica-alumina mineral rectorite and FeCu-SSZ-13 molecular sieve into a mixer and mix them evenly.

[0084] (2) Then, sodium carboxymethyl cellulose, sesbania powder, glass fiber, and straw powder are added into a mixer and mixed to obtain a uniform dry material.

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

[0086] (4) Then, add pseudo-boehmite, malic acid, nitric acid, glycerin and deionized water and knead.

[0087] (5) Repeat the kneading of the clay material in step (4) for 2 times.

[0088] (6) Seal the mud in step (5) with plastic wrap and place it in a dry and cool place for aging for 24 hours.

[0089] (7) The clay prepared in step (6) is placed in a molding machine for extrusion molding.

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

[0091] (9) Material A is dried, and its drying curve is: 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, it is transferred to a common oven at 100°C and dried for 3 hours to obtain material B.

[0092] (10) Material B is placed in a muffle furnace for calcination. The sintering curve is as follows: starting from 100°C, the temperature is increased by 0.5°C per minute, the temperature is increased to 170°C for calcination and debinding for 2 hours, the temperature is further increased to 350°C and maintained for 2 hours, and then the temperature is increased to 550°C and maintained for 8 hours to obtain a molecular sieve-based honeycomb integral denitrification catalyst.

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

[0094] Example 4

[0095] A method for preparing a molecular sieve-based honeycomb monolithic denitration catalyst for removing nitrogen oxides comprises the following steps:

[0096] The raw materials were weighed according to the following mass proportions: 60 parts of natural silica-alumina 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 bundle fibers, 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, 60 parts of natural silica-alumina mineral kaolin are first metal-modified. The specific process is as follows:

[0098] Take 60 parts of natural silica-alumina mineral kaolin, spray and load 3 parts of molybdenum nitrate solution (1 mol / L) while stirring, and after drying and crushing, the total mass increases by about 1-2 wt%.

[0099] (1) Add metal-modified natural silica-alumina mineral kaolin and FeCu-ZSM-5 molecular sieve into a mixer and mix them evenly.

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

[0101] (3) Add water-soluble polyvinyl alcohol fiber bundles and mix well.

[0102] (4) Then, add silica sol, lactic acid, nitric acid, glycerin and deionized water and knead.

[0103] (5) Repeat the kneading of the clay material in step (4) for 2 times.

[0104] (6) Seal the mud material in step (5) with plastic wrap and place it in a dry and cool place for aging for 48 hours.

[0105] (7) The clay prepared in step (6) is placed in a molding machine for extrusion molding.

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

[0107] (9) Material A is dried, and its drying curve is as follows: 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, it is transferred to an oven at 100°C and dried for 3 h to obtain material B.

[0108] (10) Material B is placed in a muffle furnace for calcination. The calcination curve is as follows: starting from 100°C, the temperature is increased by 0.5°C per minute, the temperature is increased to 230°C for calcination and debinding for 2 hours, the temperature is further increased to 420°C for calcination for 2 hours, and the temperature is increased to 650°C for calcination for 8 hours to obtain a molecular sieve-based honeycomb integral denitrification catalyst.

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

[0110] Example 5

[0111] A method for preparing a molecular sieve-based honeycomb monolithic denitration catalyst for removing nitrogen oxides comprises the following steps:

[0112] The raw materials were weighed according to the following mass proportions: 70 parts of natural silica-alumina 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 fibers, 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, 70 parts of natural silica-alumina mineral kaolin are first metal-modified. The specific process is as follows:

[0114] Take 70 parts of natural silica-alumina mineral kaolin, spray 5 parts of molybdenum nitrate solution (1 mol / L) on it while stirring, and after drying and crushing, the total mass increases by about 1-2 wt%.

[0115] (1) Add metal-modified natural silica-alumina mineral kaolin and FeCu-ZSM-5 molecular sieve into a mixer and mix them evenly.

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

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

[0118] (4) Then, aluminum sol, citric acid, boric acid, glycerin and deionized water are added and kneaded.

[0119] (5) Repeat the kneading of the clay material 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 aging for 24 hours.

[0121] (7) The clay prepared in step (6) is placed in a molding machine for extrusion molding.

[0122] (8) The formed honeycomb was pre-dried to remove 5 wt% of water and then placed in 60°C water to remove the water-soluble polyvinyl alcohol fiber bundles. After soaking for 10 hours, the honeycomb was taken out and rinsed with 60°C water for 3 times to obtain material A.

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

[0124] (10) Material B is placed in a muffle furnace for calcination. The sintering curve is as follows: starting from 100°C, the temperature is increased by 1.0°C per minute, the temperature is increased to 180°C for calcination and debinding for 2 hours, the temperature is further increased to 370°C and maintained for 2 hours, and then the temperature is increased to 550°C and maintained for 8 hours to obtain a molecular sieve-based honeycomb integral denitrification catalyst.

[0125] (11) The prepared molecular sieve-based honeycomb monolithic catalyst was placed in a monolithic catalyst evaluation device to simulate the flue gas components N2, NH3, H2O, NO, and O2, and the air velocity was maintained at 5000 h -1 , [NO] = [NH3] = 500ppm, [O2] = 5%, H2O = 5%, the NO concentration at the inlet and outlet were detected respectively, and the denitration efficiency of the catalyst was calculated. The results are shown in Table 1.

[0126] Example 6

[0127] A method for preparing a molecular sieve honeycomb monolithic catalyst for removing nitrogen oxides comprises the following steps:

[0128] The raw materials were weighed according to the following mass proportions: 75 parts of natural silica-alumina mineral kaolin, 10 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 bundle fibers, 10 parts of sawdust, 4 parts of silica sol, 1 part of lactic acid, 1 part of nitric acid, 5 parts of glycerol, and 16 parts of deionized water.

[0129] Before mixing the materials, 75 parts of natural silica-alumina mineral kaolin are first metal-modified. The specific process is as follows:

[0130] Take 75 parts of natural silica-alumina mineral kaolin, spray 5 parts of manganese nitrate solution (1 mol / L) on it while stirring, and after drying and crushing, the total mass increases by about 1-2 wt%.

[0131] (1) Add metal-modified natural silica-alumina mineral kaolin and FeCu-ZSM-5 molecular sieve into a mixer and mix them evenly.

[0132] (2) Then, sodium carboxymethyl cellulose, sesbania powder, glass fiber and sawdust are added into a mixer and mixed evenly to obtain a uniform dry material.

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

[0134] (4) Then, add silica sol, lactic acid, nitric acid, glycerin and deionized water and knead.

[0135] (5) Repeat the kneading of the clay material in step (4) for 3 times.

[0136] (6) Seal the mud material in step (5) with plastic wrap and place it in a dry and cool place for aging for 48 hours.

[0137] (7) The clay prepared in step (6) is placed in a molding machine for extrusion molding.

[0138] (8) The formed honeycomb was pre-dried to remove 5 wt% of water and then placed in 60°C water to remove the water-soluble polyvinyl alcohol fiber bundles. After soaking for 10 hours, the honeycomb was taken out and rinsed with 60°C water for 3 times to obtain material A.

[0139] (9) Material A is dried, and its drying curve is as follows: 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, it is transferred to a common oven at 100°C and dried for 3 h to obtain material B.

[0140] (10) Material B is placed in a muffle furnace and calcined. The sintering curve is as follows: the temperature is increased from 100°C to 0.5°C per minute, the temperature is increased to 200°C for debinding for 2 hours, the temperature is further increased to 400°C for sintering for 2 hours, and the temperature is further increased to 600°C for 8 hours to obtain a molecular sieve-based honeycomb integral denitrification catalyst.

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

[0142] Example 7

[0143] A method for preparing a molecular sieve-based honeycomb monolithic denitration catalyst for removing nitrogen oxides comprises the following steps:

[0144] The raw materials were weighed according to the following mass proportions: 80 parts of natural silica-alumina 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 bundle fibers, 10 parts of sawdust, 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, 80 parts of natural silica-alumina mineral kaolin are first metal-modified. The specific process is as follows:

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

[0147] (1) Add metal-modified natural silica-alumina mineral kaolin and FeCu-ZSM-5 molecular sieve into a mixer and mix them evenly.

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

[0149] (3) Add water-soluble polyvinyl alcohol fiber bundles and mix well.

[0150] (4) Then, add silica sol, lactic acid, nitric acid, glycerin and deionized water and knead.

[0151] (5) Repeat the kneading of the clay material in step (4) for 2 to 3 times.

[0152] (6) Seal the mud material in step (5) with plastic wrap and place it in a dry and cool place for aging for 48 hours.

[0153] (7) The clay prepared in step (6) is placed in a molding machine for extrusion molding.

[0154] (8) The formed honeycomb was pre-dried to remove 5 wt% of water and then placed in a 60°C water bath to remove the water-soluble polyvinyl alcohol fiber bundles. After soaking for 10 hours, the honeycomb was taken out and rinsed with 60°C water for three times to obtain material A.

[0155] (9) Material A is dried, and its drying curve is: 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; finally, it is transferred to a common oven at 100°C and dried for 3 hours to obtain material B.

[0156] (10) Material B is placed in a muffle furnace and calcined. The sintering curve is as follows: starting from 100°C, the temperature is increased by 0.5°C per minute, the temperature is increased to 250°C for debinding for 2 hours, the temperature is further increased to 450°C for sintering for 2 hours, and the temperature is then increased to 700°C for 8 hours to obtain a molecular sieve-based honeycomb integral denitrification catalyst.

[0157] (11) The prepared molecular sieve-based honeycomb monolithic denitrification catalyst was placed in a monolithic catalyst evaluation device to simulate the flue gas components N2, NH3, H2O, NO, and O2, and the air velocity was maintained at 5000 h -1 , [NO] = [NH3] = 500ppm, [O2] = 5%, H2O = 5%, the NO concentration at the inlet and outlet were detected respectively, and the denitration efficiency of the catalyst was calculated. The results are shown in Table 1.

[0158] The evaluation results of the denitration reactions of Examples 1 to 7 are shown in Table 1.

[0159] Table 1 Denitrification reaction evaluation results

[0160]

[0161]

[0162] Through experimental demonstration, the present invention selects a suitable natural silica-alumina mineral carrier, which overcomes the difficulty of pure molecular sieve catalysts being difficult to form, improves the smoothness of the extrusion process, and improves the mechanical strength after calcination. At the same time, the metal-modified natural silica-alumina mineral carrier can provide a certain catalytic activity. The present invention structurally adjusts the honeycomb body, and the water-soluble polymer bundle fibers effectively create a regular inner wall through-structure, exposing the internal embedded molecular sieve catalyst, and using the water-soluble properties to protect it from carbon poisoning. Compared with traditional commercial V-based honeycomb monolithic catalysts, the present invention uses molecular sieve catalysts as the main active component to manufacture an internally penetrated honeycomb monolithic catalyst, which implements the concept of green environmental protection and has practical application value.

Claims

1. A method for preparing a molecular sieve-based honeycomb monolithic denitration catalyst, characterized in that: The following steps are involved: (1) After uniformly mixing the molecular sieve-based catalyst and the metal-modified natural silica-alumina 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 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 humectant and water to the mixed powder, and after being fully mixed, 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 to 90° C. for 0.5 to 2.0 hours after being pre-dried, and then rinsed with water at 20 to 90° C. for 2 to 3 times.

2. The method for preparing a molecular sieve-based honeycomb monolithic denitration catalyst according to claim 1, characterized in that: 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 silicon dioxide to aluminum oxide of the molecular sieve is 2 to 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 to 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, characterized in that: 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 20wt%, and the particle size is not less than 200 meshes; 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, characterized in that: The acid solution is an organic acid and an inorganic acid solution, wherein the organic acid is one or more of citric acid, tartaric acid, malic acid, oxalic acid, and lactic acid; and the inorganic acid is one or more of hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, and boric acid. The concentrations of the organic acid aqueous solution and the inorganic acid aqueous solution are both 5 to 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 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.

8. The method for preparing a molecular sieve-based honeycomb monolithic denitration catalyst according to claim 1, characterized in that: 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 double-screw extrusion, which is carried out with molds of different shapes, and the wall thickness adjustment range is 0.5 to 3.0 mm; The pre-drying is to remove 5wt% 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 performs closed calcination in a muffle furnace.

9. The method for preparing a molecular sieve-based honeycomb monolithic denitration catalyst according to claim 1, characterized in that: The drying method is: adopting temperature and humidity coordinated cross control, the temperature is controlled at 25-100°C, and the humidity is 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, the binder is removed 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 NH3-SCR reaction.

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