CN115770565A - Flue gas denitration catalyst and preparation method thereof - Google Patents
Flue gas denitration catalyst and preparation method thereof Download PDFInfo
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- 239000003054 catalyst Substances 0.000 title claims abstract description 147
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 48
- 239000003546 flue gas Substances 0.000 title claims abstract description 48
- 238000002360 preparation method Methods 0.000 title claims abstract description 25
- 239000002243 precursor Substances 0.000 claims abstract description 111
- 239000000243 solution Substances 0.000 claims abstract description 91
- 238000002156 mixing Methods 0.000 claims abstract description 62
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 55
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims abstract description 54
- 239000010936 titanium Substances 0.000 claims abstract description 52
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- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 25
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- 229910000349 titanium oxysulfate Inorganic materials 0.000 claims description 12
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- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 3
- QGAVSDVURUSLQK-UHFFFAOYSA-N ammonium heptamolybdate Chemical compound N.N.N.N.N.N.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.O.[Mo].[Mo].[Mo].[Mo].[Mo].[Mo].[Mo] QGAVSDVURUSLQK-UHFFFAOYSA-N 0.000 claims description 3
- XUFUCDNVOXXQQC-UHFFFAOYSA-L azane;hydroxy-(hydroxy(dioxo)molybdenio)oxy-dioxomolybdenum Chemical compound N.N.O[Mo](=O)(=O)O[Mo](O)(=O)=O XUFUCDNVOXXQQC-UHFFFAOYSA-L 0.000 claims description 3
- XAYGUHUYDMLJJV-UHFFFAOYSA-Z decaazanium;dioxido(dioxo)tungsten;hydron;trioxotungsten Chemical group [H+].[H+].[NH4+].[NH4+].[NH4+].[NH4+].[NH4+].[NH4+].[NH4+].[NH4+].[NH4+].[NH4+].O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.O=[W](=O)=O.[O-][W]([O-])(=O)=O.[O-][W]([O-])(=O)=O.[O-][W]([O-])(=O)=O.[O-][W]([O-])(=O)=O.[O-][W]([O-])(=O)=O.[O-][W]([O-])(=O)=O XAYGUHUYDMLJJV-UHFFFAOYSA-Z 0.000 claims description 3
- 150000007522 mineralic acids Chemical class 0.000 claims description 3
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- 230000000694 effects Effects 0.000 abstract description 25
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- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 50
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- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 8
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- 239000002585 base Substances 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 6
- 239000012752 auxiliary agent Substances 0.000 description 5
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical group [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 4
- 238000004523 catalytic cracking Methods 0.000 description 4
- 230000003197 catalytic effect Effects 0.000 description 4
- 239000006185 dispersion Substances 0.000 description 4
- 239000011159 matrix material Substances 0.000 description 4
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 4
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 3
- 239000005977 Ethylene Substances 0.000 description 3
- MSOUIOOSDCFNQJ-UHFFFAOYSA-N [Mo].[W].[Ti] Chemical compound [Mo].[W].[Ti] MSOUIOOSDCFNQJ-UHFFFAOYSA-N 0.000 description 3
- 230000009471 action Effects 0.000 description 3
- 239000013543 active substance Substances 0.000 description 3
- 239000000084 colloidal system Substances 0.000 description 3
- 238000005336 cracking Methods 0.000 description 3
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- 241000219782 Sesbania Species 0.000 description 2
- 229910000287 alkaline earth metal oxide Inorganic materials 0.000 description 2
- UQZIWOQVLUASCR-UHFFFAOYSA-N alumane;titanium Chemical compound [AlH3].[Ti] UQZIWOQVLUASCR-UHFFFAOYSA-N 0.000 description 2
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 description 2
- 239000011609 ammonium molybdate Substances 0.000 description 2
- APUPEJJSWDHEBO-UHFFFAOYSA-P ammonium molybdate Chemical compound [NH4+].[NH4+].[O-][Mo]([O-])(=O)=O APUPEJJSWDHEBO-UHFFFAOYSA-P 0.000 description 2
- 229940010552 ammonium molybdate Drugs 0.000 description 2
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- 150000004706 metal oxides Chemical class 0.000 description 2
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- ZPZCREMGFMRIRR-UHFFFAOYSA-N molybdenum titanium Chemical compound [Ti].[Mo] ZPZCREMGFMRIRR-UHFFFAOYSA-N 0.000 description 2
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- CLIMUTTYEDYWND-UHFFFAOYSA-N [Mo](=O)(=O)=O.[O-2].[Ti+4].[O-2] Chemical compound [Mo](=O)(=O)=O.[O-2].[Ti+4].[O-2] CLIMUTTYEDYWND-UHFFFAOYSA-N 0.000 description 1
- XHCLAFWTIXFWPH-UHFFFAOYSA-N [O-2].[O-2].[O-2].[O-2].[O-2].[V+5].[V+5] Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[V+5].[V+5] XHCLAFWTIXFWPH-UHFFFAOYSA-N 0.000 description 1
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Abstract
The invention relates to a preparation method of a honeycomb type flue gas denitration catalyst, which comprises the following steps: uniformly mixing the titanium source precursor solution and the aluminum source precursor solution to obtain a mixed solution; adjusting the pH value of the mixed solution to 7-11, precipitating and filtering; mixing the filter cake with strong alkali solution, stirring, precipitating, washing and filtering; adding deionized water into the filter cake to be mixed into slurry, adding precursor solution formed by dissolving a tungsten source precursor and/or a molybdenum source precursor, uniformly mixing, drying, roasting, and grinding into powder; uniformly mixing the powder with a vanadium source precursor solution and a high molecular dispersing agent, adding deionized water, an extrusion aid, a pore-forming agent, nano silicon dioxide, glass fiber and a binder, adjusting the pH value to 7.3-9.0, uniformly mixing into a paste, extruding a honeycomb type blank, drying and roasting. The invention also relates to a honeycomb type flue gas denitration catalyst. The catalyst has balanced active center, strong poisoning resistance and stable activity.
Description
Technical Field
The invention relates to the technical field of denitration catalysts, in particular to a flue gas denitration catalyst and a preparation method thereof, and can overcome the defects of uneven dispersion and unstable activity of the denitration catalyst in active components in the prior art.
Background
Nitrogen Oxides (NO) x ) Is one of the main atmospheric pollutants, and the emission requirements are increasingly strict. The requirements of the emission standard of pollutants for petroleum refining industry issued by the national environmental protection department are as follows: beginning at 7 months and 1 day in 2015, the requirement of nitrogen oxide in regenerated flue gas discharged by newly-built catalytic cracking device is less than 200mg/m 3 Particular emission limits of less than 100mg/m 3 Existing enterprises of 7/1/2017 also implement the standard. Among the various flue gas denitration technologies, selective Catalytic Reduction (SCR) is still the mainstream technology in the world, and NO thereof x The removal rate can reach 80-90%. Among them, the denitration catalyst is the core of the SCR technology, developed countries developed a series of denitration catalysts aiming at the characteristics of coal quality, boiler type, etc. in the last 80 th century, many scientific research units and enterprises in China also carried out a series of researches aiming at the flue gas condition in China, and developed some denitration catalysts.
The Chinese application CN201010537130.0 provides a method for preparing a denitration catalyst by using a hydrothermal method, which comprises the steps of firstly mixing a titanium source precursor and a molybdenum source precursor, placing the mixture in an autoclave for hydrothermal reaction, filtering, washing and drying to obtain a titanium-molybdenum powder denitration catalyst, and simultaneously introducing elements such as vanadium, molybdenum and the like to prepare a multi-metal oxide catalyst. The active component of the catalyst prepared by the method has small crystal grains and larger specific surface area, but the phenomenon of higher aggregation degree of the same materials can be caused because the active component is not fully mixed, and the activity of the catalyst can be influenced to a certain extent. Chinese application CN201110345605.0 provides a preparation method of a denitration catalyst, ammonium molybdate and ammonium metavanadate are sequentially added into metatitanic acid slurry, ultrasonic pulping is carried out, the pH value is adjusted to 4.0-6.5, and catalyst powder is obtained through standing, separation and drying. The method has simple process and low cost, but ammonium metavanadate is added as a solid, the solubility of vanadium needs to be verified, and the long-period service performance of the catalyst is influenced although the activity is very high when the vanadium is not uniformly dispersed. The Chinese application CN201210400949.1 provides a preparation method of titanium dioxide-molybdenum trioxide composite powder, ammonium paramolybdate solution is added into metatitanic acid slurry, and the mixture is directly dried in vacuum after being stirred to obtain a finished product. The method has simple process, but the titanium-molybdenum mixing strength is lower, and the performance of the material is influenced to a certain extent. Chinese patent CN103143396B provides a preparation method of a honeycomb type denitration catalyst, titanium dioxide, silicon dioxide and active substances are mixed into paste, then a binder, glass fibers and the like are added, and finally extrusion molding is carried out. The method has simple process, but the distribution of active substances is not good, so that the denitration efficiency of the catalyst is low.
In summary, the preparation of the denitration catalyst involves the mixing of various metal oxides, the denitration performance of the catalyst cannot be completely distinguished according to the mixing mode and the preparation process, and the powder catalyst NO is x The conversion rate can reach more than 90 percent, and the activity of the formed catalyst is reduced to a certain extent, which indicates that on one hand, the catalytic activity of the specific metal oxide is higher, and higher NO can still be obtained due to uneven dispersion x The conversion rate; on the other hand, the catalyst forming process also causes the catalyst activity to be reduced. Meanwhile, the quality of the overall performance of the catalyst needs to be verified from other aspects of characterization, and the preparation of the catalyst also considers factors such as operability of industrial amplification.
Disclosure of Invention
Based on the above, the main object of the present invention is to provide a honeycomb denitration catalyst and a preparation method thereof, so as to overcome the defects of unbalanced active center, poor poisoning resistance and unstable activity of the denitration catalyst in flue gas in the prior art.
Therefore, the invention provides a preparation method of a honeycomb type flue gas denitration catalyst, which comprises the following steps:
(1) Dissolving a titanium source precursor in acid to form a solution;
(2) Dissolving an aluminum source precursor to form a solution, and uniformly mixing the solution with the solution obtained in the step (1) to obtain a mixed solution;
(3) Adjusting the pH value of the mixed solution obtained in the step (2) to 7-11, precipitating and filtering to obtain a filter cake, and washing the filter cake;
(4) Mixing the filter cake washed in the step (3) with a strong alkali solution, stirring, precipitating, washing and filtering to obtain a filter cake;
(5) Adding deionized water into the filter cake obtained in the step (4), mixing into slurry, adding a precursor solution formed by dissolving one or two of a tungsten source precursor and a molybdenum source precursor, uniformly mixing, drying, roasting, and grinding into powder;
(6) And (3) uniformly mixing the powder obtained in the step (5), a vanadium source precursor solution and a high molecular dispersing agent, adding deionized water, an extrusion aid, a pore-forming agent, nano-silica, glass fiber and a binder, adjusting the pH value to 7.3-9.0, uniformly mixing into a paste, extruding a honeycomb type blank by using an extruder, drying and roasting to obtain a finished product.
In the preparation method of the flue gas denitration catalyst, the titanium source precursor is preferably titanyl sulfate or metatitanic acid, the acid is an inorganic acid, and further preferably sulfuric acid or nitric acid, and the titanium source precursor in the solution formed in the step (1) is TiO 2 The content is 15-40 g/L.
Hair brushIn the method for preparing the flue gas denitration catalyst, it is preferable that the aluminum source precursor is aluminum sulfate, and the aluminum source precursor is Al 2 O 3 The titanium source precursor is TiO in mass 2 The mass ratio of the aluminum source precursor to the titanium source precursor is 0.1-5.0.
In the preparation method of the flue gas denitration catalyst, the alkali solution is preferably a sodium hydroxide solution, the concentration of the alkali solution is 1-8 mol/L, and the dosage of the alkali solution is 1-10 times of the mass of the soaked filter cake.
The preparation method of the flue gas denitration catalyst provided by the invention is preferably that the tungsten source precursor is ammonium paratungstate or ammonium metatungstate, the molybdenum source precursor is one or more of ammonium dimolybdate, ammonium trimolybdate, ammonium tetramolybdate, ammonium heptamolybdate and ammonium octamolybdate, and further preferably that the tungsten source precursor and the molybdenum source precursor are both calculated by the mass of trioxide, and the filter cake is calculated by the mass of TiO 2 The mass ratio of the sum of the tungsten source precursor and the molybdenum source precursor to the amount of the filter cake is 1.0-10.0.
In the preparation method of the flue gas denitration catalyst, the mixing mode is preferably stirring or ultrasonic oscillation, and the time is 0.1-30 hours; the agent for adjusting the pH value in the steps (3) and (6) is ammonia water; in the step (5), the water mass content in the slurry is 20-60%; further preferably, in the step (6), the extrusion aid is stearic acid or glycerol, and the addition amount of the extrusion aid is equal to that of TiO 2 The mass ratio of the titanium source precursor is 0.01-3.0; the pore-forming agent is one or more of polyoxyethylene, polymethyl methacrylate and sesbania powder, and the addition amount of the pore-forming agent is equal to that of TiO 2 The mass ratio of the titanium source precursor is 0.01-2.0; the binder is one or two of carboxymethyl cellulose and hydroxypropyl cellulose; the water content in the paste is 15-45% by mass; more preferably, the nano silicon dioxide, the glass fiber and the binder are added in the amount of TiO 2 The mass ratio of the titanium source precursor is respectively 0.1-3.5.
Hair brushAccording to the preparation method of the flue gas denitration catalyst, preferably, a vanadium source precursor in the vanadium source precursor solution is ammonium metavanadate; more preferably, the vanadium source precursor is represented by V 2 O 5 The titanium source precursor is TiO in mass 2 And (4) in terms of mass, the ratio of the vanadium source precursor to the titanium source precursor in the powder in the step (5) is 0.2-5.0.
In the preparation method of the flue gas denitration catalyst, the polymer dispersant is preferably one or more of polyethylene glycol, polyacrylamide and polyethylene pyrrolidone, and the addition amount of the polymer dispersant is equal to that of TiO 2 The mass ratio of the titanium source precursor is 0.1-2.0; further preferably, the roasting temperature in the step (5) and the roasting temperature in the step (6) are both 400-650 ℃, and the roasting time is both 2-40 h.
In the method for preparing a flue gas denitration catalyst according to the present invention, the number of the cells in the cross section of the honeycomb green body in the step (6) is preferably 3 × 3 to 40 × 40, and more preferably 15 × 15, 18 × 18, 20 × 20, 21 × 21, 22 × 22, 25 × 25, or 30 × 30.
The invention also provides a denitration catalyst, which is prepared by the preparation method of the denitration catalyst.
The invention has the beneficial effects that:
(1) Mixing titanium atoms and aluminum atoms at a molecular level by using an in-situ mixing method, so that crystals with lattice defects are generated in a subsequent coprecipitation process, and the mixed metal oxide has small and uniform particle size;
(2) Aluminum atoms in the titanium-aluminum crystal lattice are dissolved out by using strong base, so that the crystal lattice defect of the titanium substrate is greatly increased, the crystal lattice defect of the aluminum dissolved out by using the strong base is a surface position which is easy to contact with flue gas in the flue gas atmosphere, and the SCR catalytic activity can be effectively exerted after the position supplement of the cocatalyst component, so that the denitration effect is improved under the same condition;
(3) And one or two of tungsten and molybdenum elements are added to the titanium substrate after the aluminum element is dissolved out, and because more lattice defects exist, the tungsten or molybdenum elements are added, so that the lattice defects of the roasted hybrid substrate are more stable, and the anatase type of the crystal form of the titanium substrate can be kept from being transformed during high-temperature roasting, thereby being more beneficial to keeping high denitration effect.
(4) Under the action of a macromolecular dispersant, a vanadium source is fully dispersed on a hybridized base material, and meanwhile, under the influence of a cocatalyst component tungsten or molybdenum on the base material with larger lattice defects, the vanadium source penetrates deeper on the surface of titanium-tungsten (molybdenum) particles, is connected more tightly, is dispersed more uniformly, and has higher and stable catalyst activity after roasting.
(5) The nanometer silicon dioxide particles are used for filling gaps of titanium dioxide matrix particles, the density of a catalyst matrix is increased, the strength of the roasted catalyst is further increased, and meanwhile, the water resistance of the catalyst is improved by utilizing the surface performance of the silicon dioxide.
(6) The catalyst is prepared into a honeycomb catalyst with good activity and strength by adopting auxiliary agents such as pore-forming agents, binders, glass fibers and the like, and the honeycomb catalyst is favorable for modular assembly and long-period stable operation on an industrial denitration device.
Detailed Description
The following examples illustrate the invention in detail: the present example is carried out on the premise of the technical scheme of the present invention, and detailed embodiments and processes are given, but the scope of the present invention is not limited to the following examples, and the experimental methods without specific conditions noted in the following examples are generally performed according to conventional conditions.
The invention provides a preparation method of a honeycomb type flue gas denitration catalyst, which comprises the following steps:
(1) Dissolving a titanium source precursor in acid to form a solution;
(2) Dissolving an aluminum source precursor to form a solution, and uniformly mixing the solution with the solution obtained in the step (1) to obtain a mixed solution;
(3) Adjusting the pH value of the mixed solution obtained in the step (2) to 7-11, precipitating and filtering to obtain a filter cake, and washing the filter cake;
(4) Mixing the filter cake washed in the step (3) with a strong alkali solution, stirring, precipitating, washing and filtering to obtain a filter cake;
(5) Adding deionized water into the filter cake obtained in the step (4), mixing into a slurry state, adding a precursor solution formed by dissolving one or two of a tungsten source precursor and a molybdenum source precursor, uniformly mixing, drying, roasting, and grinding into powder;
(6) And (3) uniformly mixing the powder obtained in the step (5), a vanadium source precursor solution and a high molecular dispersing agent, adding deionized water, an extrusion aid, a pore-forming agent, nano-silica, glass fiber and a binder, adjusting the pH value to 7.3-9.0, uniformly mixing into a paste, extruding a honeycomb type blank by using an extruder, drying and roasting to obtain a finished product.
In some embodiments, it is preferred that the titanium source precursor is titanyl sulfate or metatitanic acid, the acid is an inorganic acid, further preferably sulfuric acid or nitric acid, and the titanium source precursor in the solution formed in step (1) is TiO 2 The content is 15-40 g/L.
In some embodiments, it is preferred that the aluminum source precursor is aluminum sulfate and the aluminum source precursor is Al 2 O 3 The titanium source precursor is TiO in mass 2 The mass ratio of the aluminum source precursor to the titanium source precursor is 0.1-5.0.
In some embodiments, it is preferred that the strong alkaline solution is a sodium hydroxide solution having a concentration of 1 to 8mol/L and used in an amount of 1 to 10 times the mass of the cake to be leached.
In some embodiments, it is preferable that the tungsten source precursor is ammonium paratungstate or ammonium metatungstate, the molybdenum source precursor is one or more of ammonium dimolybdate, ammonium trimolybdate, ammonium tetramolybdate, ammonium heptamolybdate and ammonium octamolybdate, and it is further preferable that the tungsten source precursor and the molybdenum source precursor are both calculated by mass of trioxide, and the filter cake is calculated by mass of TiO 2 The mass ratio of the sum of the tungsten source precursor and the molybdenum source precursor to the amount of the filter cake is 1.0-10.0.
In some embodiments, it is preferable that the mixing is performed by stirring or ultrasonic oscillation for 0.1 to 30 hours; the agent for adjusting the pH value in the steps (3) and (6) is ammonia water; in the step (5), the water mass content in the slurry is 20-60%; it is further preferred that the first and second liquid crystal compositions,in the step (6), the extrusion aid is stearic acid or glycerol, and the addition amount of the extrusion aid is equal to that of TiO 2 The mass ratio of the titanium source precursor is 0.01-3.0; the pore-forming agent is one or more of polyoxyethylene, polymethyl methacrylate and sesbania powder, and the addition amount of the pore-forming agent is equal to that of TiO 2 The mass ratio of the titanium source precursor is 0.01-2.0; the binder is one or two of carboxymethyl cellulose and hydroxypropyl cellulose; the water content in the paste is 15-45% by mass; more preferably, the nano silicon dioxide, the glass fiber and the binder are added in the amount of TiO 2 The mass ratio of the titanium source precursor is respectively 0.1-3.5.
In some embodiments, it is preferable that the vanadium source precursor in the vanadium source precursor solution is ammonium metavanadate; further preferably, the vanadium source precursor is represented by V 2 O 5 The titanium source precursor is TiO in mass 2 And (3) the ratio of the vanadium source precursor to the titanium source precursor in the powder in the step (5) is 0.2-5.0 by mass.
In some embodiments, it is preferable that the polymeric dispersant is one or more selected from polyethylene glycol, polyacrylamide and polyethylene pyrrolidone, and the polymeric dispersant is added in an amount corresponding to that of TiO 2 The mass ratio of the titanium source precursor is 0.1-2.0; further preferably, the roasting temperature in the step (5) and the roasting temperature in the step (6) are both 400-650 ℃, and the roasting time is both 2-40 h.
In some embodiments, it is preferable that the number of cells of the cross section of the honeycomb green body in the step (6) is 3 × 3 to 40 × 40 cells, and further preferably 15 × 15, 18 × 18, 20 × 20, 21 × 21, 22 × 22, 25 × 25, or 30 × 30 cells.
The denitration catalyst provided by the invention is prepared by the preparation method of the denitration catalyst.
Titanium source precursor solution:
in the present invention, the titanium source precursor is dissolved in sulfuric acid to form a solution, and the titanium source precursor is not particularly limited, and is usually limited to titanyl sulfate or metatitanic acid, and the titanium source precursor in the titanium source precursor solution isIn bulk with TiO 2 The content of the titanium source precursor is 15-40 g/L by mass. If the concentration is less than 15g/L, the solution is too dilute, the combination with other materials is loose, and the production efficiency is low; if it exceeds 40g/L, the mixing strength with other materials is lowered due to too high concentration, resulting in poor fusion.
The flue gas denitration catalyst comprises the following components:
in the invention, the denitration catalyst mainly comprises a titanium source precursor, a tungsten source precursor, a molybdenum source precursor, a vanadium source precursor, a pore-forming auxiliary agent, a binder, a structural auxiliary agent and the like, and if the tungsten source or molybdenum source precursor is less, the dispersion of main active substances and the activity stability of the catalyst are influenced, so that the performance of the catalyst is poor; if the pore-forming amount is large, the adsorption of tungsten or molybdenum on the surface of catalyst particles is influenced, and if the pore-forming amount is too small, the porosity of the catalyst is influenced; the catalyst forming is influenced by less binder, and the catalyst forming strength is influenced by too much binder; too much structure promoter makes the catalyst difficult to shape, and too little results in a decrease in catalyst strength.
Mixing process of shaped catalyst sample with dust in flue gas (which may be the dust of catalytic cracking flue gas or flue gas of other devices): in the air atmosphere, at 350 ℃, flue gas dust actually collected is circularly introduced into a prepared fresh catalyst pore channel for 24 hours, the particle size distribution of the dust is not uniform, and impurities such as colloidal particles, nickel oxide, alkali and alkaline earth metal oxide can be contained. In the contact process of the fresh catalyst and the flue gas dust, heavy metals in the dust are transferred to the fresh catalyst, so that the surface activity of the fresh catalyst is reduced, and the overall performance of the denitration catalyst is reduced.
NO x Conversion evaluation conditions: space velocity of 5000h -1 Reaction temperature of 350 ℃ and inlet gas NO x Is 600mg/Nm 3 、SO 2 Is 1000mg/Nm 3 The ammonia-nitrogen ratio is 1, and the water content is 10%.
NO x 、SO 2 The concentration measuring method comprises the following steps: smoke continuous on-line analyzer, siemens ULTRAMAT23.
SO 2 /SO 3 The conversion rate determination method comprises the following steps: limestone-gypsum wet flue gas desulfurization device performance acceptance test specification (DL/T998-200)6)。
The following examples are specific illustrations of the present invention, and "%" described in examples and comparative examples means mass percent.
Example 1:
will contain TiO 2 Dissolving 1000g of titanyl sulfate in a mass meter in sulfuric acid to form a solution; will contain Al 2 O 3 40g of aluminum sulfate in mass was dissolved in deionized water to form a solution. Uniformly mixing the two solutions, adjusting the pH value to 10 by using ammonia water, precipitating, filtering to obtain a filter cake, and washing the filter cake; putting the washed filter cake into a sodium hydroxide solution with the mass of 5mol/L and 3 times of that of the filter cake, stirring for 10 hours, fully washing and filtering to obtain a filter cake; the filter cake is made into slurry (slurry) with water content of 45% by deionized water, and WO is added 3 50g of ammonium metatungstate solution is stirred for 3 hours, dried, roasted at 550 ℃ for 2 hours and ground into powder; mixing the powder with V 2 O 5 Uniformly mixing 10g of ammonium metavanadate solution and 8g of polyvinylpyrrolidone, adding 8g of stearic acid, 7g of polyethylene oxide, 12g of nano-silica, 50g of glass fiber, 8g of carboxymethyl cellulose and deionized water, uniformly mixing to prepare a paste (paste) containing 31% of water, adjusting the pH value to 8.3, extruding a honeycomb type blank with 6 x 6 holes on a section of 30 x 30mm by using an extruder, drying the blank, heating to 615 ℃, and roasting for 9 hours to obtain the honeycomb type denitration catalyst.
The fresh catalyst and the catalyst after being mixed with dust in catalytic cracking regeneration flue gas at high temperature are respectively evaluated. Evaluation results were as follows: fresh catalyst NO x Conversion rate is 99.3%, and catalyst NO is obtained after mixing treatment x The conversion was 99.1%.
Comparative example 1:
will contain TiO 2 Dissolving 1000g of titanyl sulfate in a mass meter in sulfuric acid to form a solution, adjusting the pH value to 10 by using ammonia water, precipitating, filtering and washing; preparing the filtered material into slurry with the water content of 45% by using deionized water, and adding WO 3 50g of ammonium metatungstate solution is stirred for 3 hours, dried, roasted at 550 ℃ for 2 hours and ground into powder; mixing the powder with V 2 O 5 10g of ammonium metavanadate solution and 8g of polyethyleneUniformly mixing the vinylpyrrolidone, adding 8g of stearic acid, 7g of polyoxyethylene, 12g of nano silicon dioxide, 50g of glass fiber, 8g of carboxymethyl cellulose and deionized water, uniformly mixing to prepare a paste containing 31% of water, adjusting the pH value to 8.3, extruding a honeycomb catalyst blank with 6X 6 holes on a section of 30X 30mm by using an extruder, drying the blank, heating to 615 ℃, and roasting for 9 hours to obtain the honeycomb denitration catalyst.
In contrast to example 1, the catalyst was prepared without an aluminum precursor and alkali treatment step.
The fresh catalyst and the catalyst after being mixed with dust in catalytic cracking regeneration flue gas at high temperature are respectively evaluated. Evaluation results were as follows: fresh catalyst NO x Conversion rate is 95.7%, and catalyst NO is obtained after mixing treatment x The conversion was 93.6%.
Example 2
Will contain TiO 2 Dissolving 1000g of titanyl sulfate in a mass meter in sulfuric acid to form a solution; will contain Al 2 O 3 30g of aluminum sulfate in a mass meter is dissolved in deionized water to form a solution. Uniformly mixing the two solutions, adjusting the pH value to 9.5 by using ammonia water, precipitating, filtering and washing; putting the washed material into sodium hydroxide solution with the mass of 3mol/L and 2 times of that of the powder, stirring for 9 hours, fully washing and filtering; preparing the filtered material into slurry with the water content of 35% by using deionized water, and adding WO 3 Stirring 40g of ammonium metatungstate solution by mass for 5 hours, drying, roasting at 500 ℃ for 3 hours, and grinding into powder; mixing the powder with V 2 O 5 8g of ammonium metavanadate solution and 7g of polyethylene glycol are uniformly mixed according to the mass, then 7g of stearic acid, 8g of polyethylene oxide, 15g of nano silicon dioxide, 45g of glass fiber, 9g of carboxymethyl cellulose and deionized water are added, the mixture is uniformly mixed to prepare a paste containing 28% of water, the pH value is adjusted to 8.0, a honeycomb type blank with 5 x 5 holes on a section of 30 x 30mm is extruded by an extruder, and after the blank is dried, the temperature is raised to 620 ℃ and the honeycomb type flue gas denitration catalyst is obtained after the blank is roasted for 8 hours.
The fresh catalyst and the catalyst after being mixed with colloid dust in the flue gas of the ethylene cracking furnace at high temperature are respectively evaluated. Evaluation results were as follows: fresh catalyst NO x Conversion rate is 99.1%, and catalyst NO is obtained after mixing treatment x The conversion rate was 98.8%.
Comparative example 2
Will contain TiO 2 Dissolving 1000g of titanyl sulfate in a mass meter in sulfuric acid to form a solution; will contain Al 2 O 3 30g of aluminum sulfate in a mass meter is dissolved in deionized water to form a solution. Uniformly mixing the two solutions, adjusting the pH value to 9.5 by using ammonia water, precipitating, filtering and washing; putting the washed material into sodium hydroxide solution with the mass of 3mol/L and 2 times of that of the powder, stirring for 9 hours, fully washing and filtering; preparing the filtered material into slurry with the water content of 35% by using deionized water, and adding WO 3 Stirring 40g of ammonium metatungstate solution by mass for 5 hours, drying, roasting at 500 ℃ for 3 hours, and grinding into powder; mixing the powder with V 2 O 5 8g of ammonium metavanadate solution, 7g of stearic acid, 8g of polyethylene oxide, 15g of nano silicon dioxide, 45g of glass fiber, 9g of carboxymethyl cellulose and deionized water in mass are uniformly mixed to prepare a paste containing 28% of water, the pH value is adjusted to be 8.0, a honeycomb catalyst blank with 5 × 5 holes on a section of 30 × 30mm is extruded by an extruder, and after the blank is dried, the temperature is raised to 620 ℃ and the honeycomb catalyst for flue gas denitration is obtained after roasting for 8 hours.
In contrast to example 2, no polymeric dispersant was involved in the catalyst preparation step.
The fresh catalyst and the catalyst after being mixed with colloid dust in the smoke of the ethylene cracking furnace at high temperature are respectively evaluated. Evaluation results were as follows: fresh catalyst NO x Conversion rate is 94.9%, and catalyst NO is obtained after mixing treatment x The conversion was 93.0%.
Example 3
Will contain TiO 2 Dissolving titanyl sulfate with the mass of 10kg in sulfuric acid to form a solution; will contain Al 2 O 3 200g of aluminum sulfate in mass is dissolved in deionized water to form a solution. Uniformly mixing the two solutions, adjusting the pH value to 9.5 by using ammonia water, precipitating, filtering and washing; putting the washed materials into a sodium hydroxide solution with the mass of 2mol/L and 3 times of that of the powder, stirring for 9 hours, fully washing and filtering; the filtered material is made into the product with the water content of50% of a slurry, to which WO is added 3 Stirring 600g of ammonium metatungstate solution by mass for 5 hours, drying, roasting at 550 ℃ for 4 hours, and grinding into powder; mixing the powder with V 2 O 5 60g of ammonium metavanadate solution and 60g of polyacrylamide are uniformly mixed according to the mass, then 80g of stearic acid, 90g of polyethylene oxide, 100g of nano silicon dioxide, 400g of glass fiber, 80g of carboxymethyl cellulose and deionized water are added, the mixture is uniformly mixed to prepare a paste containing 27.5% of water, the pH value is adjusted to 8.5, a honeycomb catalyst blank with 21 x 21 holes on a cross section of 150 x 150mm is extruded by an extruder, and after the blank is dried, the temperature is raised to 620 ℃ and the honeycomb catalyst for flue gas denitration is obtained after roasting for 8 hours.
The fresh catalyst obtained above was evaluated. Evaluation results were as follows: fresh catalyst NO x The conversion was 98.9%.
Comparative example 3
Will contain TiO 2 Dissolving titanyl sulfate with the mass of 10kg in sulfuric acid to form a solution; will contain Al 2 O 3 200g of aluminum sulfate in mass is dissolved in deionized water to form a solution. Uniformly mixing the two solutions, adjusting the pH value to 9.5 by using ammonia water, precipitating, filtering and washing; preparing the filtered material into slurry with water content of 50% by using deionized water, and adding WO 3 Stirring 600g of ammonium metatungstate solution by mass for 5 hours, drying, roasting at 550 ℃ for 4 hours, and grinding into powder; mixing the powder with V 2 O 5 60g of ammonium metavanadate solution and 60g of polyacrylamide are uniformly mixed, then 80g of stearic acid, 90g of polyethylene oxide, 100g of nano silicon dioxide, 400g of glass fiber, 80g of carboxymethyl cellulose and deionized water are added, the mixture is uniformly mixed to prepare a paste containing 27.5% of water, the pH value is adjusted to 8.5, a honeycomb catalyst blank with 21 x 21 holes on a cross section of 150 x 150mm is extruded by an extruder, and after the blank is dried, the temperature is raised to 620 ℃ and the honeycomb denitration catalyst is obtained after roasting for 8 hours.
In contrast to example 3, the catalyst was prepared without an alkaline leaching of the aluminum element.
The fresh catalyst obtained above was evaluated. Evaluation results were as follows: fresh catalyst NO x The conversion was 95.1%.
Example 4
Will contain TiO 2 Dissolving titanyl sulfate with the mass of 10kg in sulfuric acid to form a solution; will contain Al 2 O 3 150g of aluminum sulfate in mass was dissolved in deionized water to form a solution. Uniformly mixing the two solutions, adjusting the pH value to 10 by using ammonia water, precipitating, filtering and washing; putting the washed materials into 2mol/L sodium hydroxide solution with the mass 2 times that of the powder, stirring for 9 hours, fully washing and filtering; preparing the filtered material into slurry with water content of 40% by using deionized water, and adding MO 3 350g of ammonium molybdate solution by mass is stirred for 5 hours, dried, roasted for 4 hours at 500 ℃ and ground into powder; mixing the powder with V 2 O 5 70g of ammonium metavanadate solution and 75g of polyvinylpyrrolidone are uniformly mixed according to the mass, then 80g of glycerol, 70g of polyethylene oxide, 150g of nano-silica, 300g of glass fiber, 65g of hydroxypropyl cellulose and deionized water are added, the mixture is uniformly mixed to prepare a paste containing 29% of water, the pH value is adjusted to 7.8, a honeycomb catalyst blank with 22 x 22 holes on a cross section of 150 x 150mm is extruded by an extruder, and the honeycomb denitration catalyst is obtained after the blank is dried and heated to 600 ℃ for roasting for 8 hours.
The fresh catalyst and the catalyst after being mixed with colloid dust in the flue gas of the ethylene cracking furnace at high temperature are respectively evaluated. Evaluation results were as follows: fresh catalyst NO x Conversion rate of 98.7%, mixed treated catalyst NO x The conversion was 98.6%.
Example 5
Will contain TiO 2 Dissolving titanyl sulfate with the mass of 10kg in sulfuric acid to form a solution; will contain Al 2 O 3 300g of aluminum sulfate in a mass meter is dissolved in deionized water to form a solution. Uniformly mixing the two solutions, adjusting the pH value to 10.5 by using ammonia water, precipitating, filtering and washing; putting the washed materials into sodium hydroxide solution with the mass of 4mol/L and 2 times of that of the powder, stirring for 9 hours, fully washing and filtering; preparing the filtered material into slurry with the water content of 40% by using deionized water, and adding WO 3 Stirring 300g of ammonium metatungstate solution by mass for 5 hours, drying, roasting at 550 ℃ for 4 hours, and grinding into powder; mixing the powder with V 2 O 5 Metavanadium with mass of 90gUniformly mixing an ammonium acid solution and 70g of polyvinylpyrrolidone, then adding 100g of stearic acid, 80g of polyethylene oxide, 200g of nano silicon dioxide, 350g of glass fiber, 75g of carboxymethyl cellulose and deionized water, uniformly mixing to prepare a paste containing 27.5% of water, adjusting the pH value to 8.0, extruding an 18X 18-hole honeycomb catalyst blank on a 150X 150mm section by using an extruder, drying the blank, heating to 610 ℃, and roasting for 8 hours to obtain the honeycomb denitration catalyst.
The fresh catalyst and the catalyst after being mixed with dust in the flue gas of the coal-fired boiler at a high temperature are respectively evaluated. Evaluation results were as follows: fresh catalyst NO x Conversion rate of 99.4%, mixed treated catalyst NO x The conversion was 99.3%.
Through the examples and comparative examples, it was found that: the honeycomb denitration catalyst of the embodiment has a good denitration effect, the titanium substrate and the aluminum element form an excellent solid solution material through primary in-situ mixing, the aluminum element is leached out through an alkali fusion process, and then the cocatalyst component is supplemented to enter the substrate, so that the high-temperature crystal form stability of the catalyst substrate and the lattice distortion of the substrate can be increased, and meanwhile, the uniform dispersion of the main active material vanadium species can be promoted, and the denitration activity of the catalyst is further improved. Under the action of a polymer dispersant, vanadium oxide is introduced on a titanium-tungsten (molybdenum) base material prepared by a novel method, a paste with good formability is formed under the assistance of forming materials such as a pore-forming agent, an inorganic auxiliary agent and the like, a honeycomb type denitration catalyst blank is prepared by an extrusion process, and the honeycomb type denitration catalyst is obtained after roasting. NO in catalyst evaluation x The conversion rate of (A) is that the ammonia-nitrogen ratio is 1 and the space velocity is 5000h -1 In the process, the denitration rate can reach more than 98 percent, and the good denitration performance is shown; after the catalyst is mixed with actual flue dust, the activity of the catalyst is only slightly reduced, which indicates that the catalyst has excellent performance; in the preparation method of the denitration catalyst, if the step (3) is not carried out, the leaching of aluminum element is not carried out, the denitration activity of a roasted catalyst sample is poor, and the denitration activity is reduced more after the mixture treatment with flue dust; if the high molecular dispersant is not added in the treatment of the step (6), the denitration activity of the roasted catalyst sample is poor, and after the catalyst sample is mixed with flue dust,the denitration activity is also obviously reduced. In a word, when the fresh denitration catalyst and the treated catalyst prepared by the invention are evaluated under the same condition, the activity is higher than that of a comparative sample, and the catalyst has good catalytic activity.
In conclusion, the invention has the beneficial effects that:
(1) Mixing titanium atoms and aluminum atoms at a molecular level by using an in-situ mixing method, so that crystals with lattice defects are generated in a subsequent coprecipitation process, and the mixed metal oxide has small and uniform particle size;
(2) Aluminum atoms in the titanium-aluminum crystal lattice are dissolved out by using strong base, so that the crystal lattice defect of the titanium substrate is greatly increased, the crystal lattice defect of the aluminum dissolved out by using the strong base is a surface position which is easy to contact with flue gas in the flue gas atmosphere, and the SCR catalytic activity can be effectively exerted after the position supplement of the cocatalyst component, so that the denitration effect is improved under the same condition;
(3) And one or two of tungsten and molybdenum elements are added to the titanium substrate after the aluminum element is dissolved out, and the tungsten or molybdenum elements are added due to the existence of more lattice defects, so that the lattice defects of the roasted hybrid substrate are more stable, and the crystal form of the titanium substrate can keep anatase type from being transformed during high-temperature roasting, thereby being more beneficial to keeping high denitration effect.
(4) Under the action of a macromolecular dispersant, a vanadium source is fully dispersed on a hybridized base material, and meanwhile, under the influence of a cocatalyst component tungsten or molybdenum on the base material with larger lattice defects, the vanadium source penetrates deeper on the surface of titanium-tungsten (molybdenum) particles, is connected more tightly, is dispersed more uniformly, and has higher and stable catalyst activity after roasting.
(5) The nanometer silicon dioxide particles are used for filling gaps of titanium dioxide matrix particles, the density of a catalyst matrix is increased, the strength of the roasted catalyst is further increased, and meanwhile, the water resistance of the catalyst is improved by utilizing the surface performance of the silicon dioxide.
(6) The catalyst is prepared into a honeycomb catalyst with good activity and strength by adopting auxiliary agents such as pore-forming agents, binders, glass fibers and the like, and the honeycomb catalyst is favorable for modular assembly and long-period stable operation on an industrial denitration device.
The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and it is therefore intended that all such changes and modifications as fall within the true spirit and scope of the invention be considered as within the following claims.
Claims (10)
1. The preparation method of the flue gas denitration catalyst is characterized by comprising the following steps of:
(1) Dissolving a titanium source precursor in acid to form a titanium source precursor solution;
(2) Dissolving an aluminum source precursor to form a solution, and uniformly mixing the solution with a titanium source precursor solution to obtain a mixed solution;
(3) Adjusting the pH value of the mixed solution to 7-11, precipitating, filtering and washing to obtain a filter cake;
(4) Mixing the filter cake with a strong alkali solution, stirring, precipitating, washing and filtering to obtain a filter cake;
(5) Adding deionized water into the filter cake obtained in the step (4), mixing into slurry, adding an active component precursor solution formed by dissolving one or two of a tungsten source precursor and a molybdenum source precursor, uniformly mixing, drying, roasting, and grinding into powder;
(6) And (3) uniformly mixing the powder obtained in the step (5), a vanadium source precursor solution and a high molecular dispersant, then adding deionized water, an extrusion aid, a pore-forming agent, nano-silica, glass fiber and a binder, adjusting the pH value to 7.3-9.0, uniformly mixing to obtain a paste, extruding to obtain a honeycomb type blank, drying and roasting to obtain a finished product.
2. The method for preparing the flue gas denitration catalyst according to claim 1, wherein the titanium source precursor is titanyl sulfate or metatitanic acid, the acid is an inorganic acid, preferably sulfuric acid or nitric acid, and the content of the titanium source precursor in the titanium source precursor solution is TiO 2 The weight is 15-40 g/L.
3. The method for preparing a flue gas denitration catalyst according to claim 1,the precursor of the aluminum source is aluminum sulfate, and the precursor of the aluminum source is Al 2 O 3 The titanium source precursor is TiO in mass 2 And the mass ratio of the aluminum source precursor to the titanium source precursor in the mixed solution is 0.1-5.0.
4. The method for preparing a flue gas denitration catalyst according to claim 1, wherein the strong alkali solution is a sodium hydroxide solution, the concentration of the sodium hydroxide solution is 1-8 mol/L, and the dosage of the sodium hydroxide solution is 1-10 times of the mass of the leached filter cake.
5. The method for preparing the flue gas denitration catalyst according to claim 1, wherein the tungsten source precursor is ammonium paratungstate or ammonium metatungstate, and the molybdenum source precursor is one or more of ammonium dimolybdate, ammonium trimolybdate, ammonium tetramolybdate, ammonium heptamolybdate and ammonium octamolybdate; preferably, the tungsten source precursor and the molybdenum source precursor are both calculated by the mass of trioxide, and the filter cake is calculated by TiO 2 And in terms of mass, the ratio of the sum of the tungsten source precursor and the molybdenum source precursor in the active component precursor solution to the dosage of the filter cake is 1.0-10.0.
6. The preparation method of the flue gas denitration catalyst according to claim 1, wherein the mixing is performed by stirring or ultrasonic oscillation for 0.1-30 hours; the agent for adjusting the pH value in the steps (3) and (6) is ammonia water; in the step (5), the water content in the slurry is 20-60% by mass; preferably, in the step (6), the extrusion aid is stearic acid or glycerol, and the addition amount thereof is TiO 2 The mass ratio of the titanium source precursor is 0.01-3.0; the pore-forming agent is one or more of polyoxyethylene, polymethyl methacrylate and sesbania powder, and the addition amount of the pore-forming agent is equal to that of TiO 2 The mass ratio of the titanium source precursor is 0.01-2.0; the binder is one or two of carboxymethyl cellulose and hydroxypropyl cellulose; the water content in the paste is 15-45% by mass; further preferably, nano silicon dioxide, glass fiber and binder are addedIn an amount corresponding to TiO 2 The mass ratio of the titanium source precursor is respectively 0.1-3.5.
7. The method for preparing a flue gas denitration catalyst according to claim 1, wherein a vanadium source precursor in the vanadium source precursor solution is ammonium metavanadate; preferably, the vanadium source precursor is represented by V 2 O 5 The titanium source precursor is TiO in mass 2 And (4) in terms of mass, the ratio of the vanadium source precursor to the titanium source precursor in the powder in the step (5) is 0.2-5.0.
8. The method for preparing a flue gas denitration catalyst according to claim 1, wherein the polymeric dispersant is one or more selected from polyethylene glycol, polyacrylamide and polyethylene pyrrolidone, and the addition amount thereof is equal to that of TiO 2 The mass ratio of the titanium source precursor is 0.1-2.0; preferably, the roasting temperature in the step (5) and the roasting temperature in the step (6) are both 400-650 ℃, and the roasting time is both 2-40 h.
9. The method of producing a flue gas denitration catalyst according to claim 1, wherein the number of cells in the cross section of the honeycomb green body in the step (6) is 3 × 3 to 40 × 40 cells, preferably 15 × 15, 18 × 18, 20 × 20, 21 × 21, 22 × 22, 25 × 25 or 30 × 30 cells.
10. A flue gas denitration catalyst, characterized by being produced by the method for producing a denitration catalyst according to any one of claims 1 to 9.
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