CN111097519A - High-temperature denitration catalyst and carrier with high thermal stability and preparation method thereof - Google Patents
High-temperature denitration catalyst and carrier with high thermal stability and preparation method thereof Download PDFInfo
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- CN111097519A CN111097519A CN201911336844.2A CN201911336844A CN111097519A CN 111097519 A CN111097519 A CN 111097519A CN 201911336844 A CN201911336844 A CN 201911336844A CN 111097519 A CN111097519 A CN 111097519A
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- B01J31/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
- B01J31/0272—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides containing elements other than those covered by B01J31/0201 - B01J31/0255
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- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/8621—Removing nitrogen compounds
- B01D53/8625—Nitrogen oxides
- B01D53/8628—Processes characterised by a specific catalyst
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Abstract
The invention discloses a low-tungsten high-temperature denitration catalyst, a carrier and a preparation method thereof, wherein calcined anatase TiO2 is prepared, and the specific surface area of the TiO2 crude product is 80-90m2And/g, adding acid or alkali to adjust the pH value of the inorganic salts of Si and W in sequence after the inorganic salts are subjected to wetting, sanding and depolymerization, so that the inorganic salts of Si and W are uniformly and chemically deposited and coated on the surfaces of titanium white particles in an oxide form, and modifying the surfaces of the titanium white particles to improve the thermal stability of the titanium white. WO3The dosage is obviously lower than that of the conventional product, but the thermal stability of the product is obviously better than that of the conventional product, and the production cost is also saved on the premise of ensuring the performance of the product.
Description
Technical Field
The invention relates to the field of environment-friendly materials, in particular to a carrier material of a high-temperature flue gas denitration catalyst, which is mainly TiO2And a high-temperature flue gas denitration catalyst and a preparation method thereof.
Background
In recent years, with the rapid development of national economy and industry, the discharge amounts of industrial waste gas, industrial coal, thermal power generation coal and automobile exhaust gas are increasing year by year. Particularly, nitric oxide in the emission of coal-fired flue gas forms nitric acid in the air, so the nitric oxide becomes one of the main harmful substances polluting the atmosphere at present, and the removal of the nitric oxide in the flue gas is very urgent. Selective catalytic reduction (SCR for short) denitration refers to the selective reduction of nitrogen oxides (Nox) into pollution-free nitrogen by using a reducing agent NH3 at a certain temperature and under the action of a catalyst, so as to achieve the purpose of purifying air. The SCR technology has the advantages of low reaction temperature, high purification rate, reliable operation, small secondary pollution and the like, and is the most widely applied flue gas denitration technology at present.
The prior SCR denitration technology takes anatase titanium dioxide as a carrier, about 1 percent of SiO2 is added, about 5 percent of WO3 and 2 to 5 percent of load vanadium oxide are used as active substances, and the catalyst is the most widely applied denitration catalyst at present. Wherein the denitration catalyst carrier belongs to a core material, accounts for 80-90% of the weight of the denitration catalyst, and the performance of the denitration catalyst carrier is directly related to the denitration rate. The titanium dioxide has good quantum size effect and surface effect, so the titanium dioxide has obvious advantages when being used for a catalyst carrier. However, in the actual use process, when the flue gas temperature is too high, the fine crystal grains of the anatase titanium dioxide are easy to grow, hard agglomeration of large crystal grains is caused, the specific surface area is reduced, and the catalytic activity is reduced. Thus 5% of WO in the production of titanium dioxide for denitration catalyst3The thermal stability of the denitration catalyst is improved, but because the metered ammonium paratungstate or ammonium metatungstate is mainly directly added into the metatitanic acid dihydrate in the production process, and the titanium dioxide powder for the denitration catalyst is prepared by uniformly mixing, high-temperature roasting and mechanical crushing, most of WO3 is wrapped in the titanium dioxide, the utilization rate is greatly reduced, the cost is increased, the using effect is poor and the like; in addition, the high-temperature thermal stability is poor, and the specific surface area is obviously reduced at high temperature.
For example, the preparation method of the silica-modified titanium dioxide forming carrier disclosed in the Chinese patent publication No. CN102139231B comprises the steps of mixing titanium dioxide powder, a carbon source and a silicon source with water to prepare a mixture slurry, drying the mixture slurry, uniformly mixing the mixture slurry with water, a binder and nitric acid, fully kneading, extruding and forming to obtain a forming carrier, and roasting to obtain the titanium dioxide forming carrier. The method coats the silicon source on the titanium dioxide powder formed after hydrolytic calcination, and the titanium dioxide powder is not good in coating effect because the titanium dioxide powder is agglomerated, the silicon source cannot be fully and uniformly attached to the surface of the titanium dioxide, the inhibition of the agglomeration degree among titanium dioxide particles is questionable, the specific surface area of the modified titanium dioxide carrier is increased very limitedly, and the poor coating effect can cause the thermal stability of the specific surface area of the titanium dioxide carrier at high temperature to be poor.
Disclosure of Invention
The invention aims to solve the technical problem that the conventional titanium dioxide carrier is poor in high-temperature thermal stability, and provides a high-temperature denitration catalyst and carrier with high thermal stability and a preparation method thereof. The method is mainly characterized in that organic silicon is added in the hydrolysis process of titanium liquid to carry out surface modification on hydrolyzed TiO2 particles, so that the denitration efficiency and the service life of the SCR denitration catalyst in high-temperature flue gas are improved.
The technical scheme of the invention is as follows: the preparation method of the low-tungsten high-temperature denitration catalyst carrier comprises the following steps: (1) after the first boiling of the hydrolysis procedure in the production of titanium dioxide by a sulfuric acid method is finished, keeping the temperature at 80-90 ℃, uniformly and slowly adding epoxy silane which is measured according to the content of 3-13 percent of SiO2 for 30-70 min; (2) after the epoxy silane is added, starting steam to raise the temperature to 105-110 ℃, keeping the micro-boiling state for 15-20min, then reducing the steam flow, keeping the temperature at 80-90 ℃, and preserving the heat for 4 h; (3) washing hydrolyzed metatitanic acid with water twice, squeezing by a membrane filter press, and obtaining a filter cake with water content of about 50% after squeezing; (4) the filter cake is sent into a rotary kiln for calcination, the temperature of one zone is controlled to be 660-class 820 ℃, the negative pressure of the kiln tail is controlled to be 100-class 150Pa, and the calcination time is 4h, so that the TiO for the denitration catalyst is obtained2A crude product; (5) pulverizing the crude product with a micro-powder mill, and controlling the particle size D50 after pulverizing<1.1，D90<2.5 packaging to obtain TiO for the denitration catalyst2And (5) finishing.
The high-temperature denitration catalyst carrier with high thermal stability is prepared by the preparation method of the high-temperature denitration catalyst carrier with high thermal stability.
The high-temperature denitration catalyst with high thermal stability comprises the high-temperature denitration catalyst with high thermal stability.
The invention has the beneficial effects that the titanium pigment is added after the hydrolysis procedure of the sulfuric acid method titanium pigment production is finishedEpoxy silane, when the titanium dioxide particles are basically molded, active bonds Si-O of the epoxy silane and hydroxyl groups Ti-OH on the surface of the titanium dioxide form Ti-O-Si. Thereby the organic silicon is evenly attached to the TiO2The surface of (2) improves the thermal stability of the high-temperature denitration catalyst carrier.
Detailed Description
The technical solution of the present invention is clearly and completely described below with reference to the following embodiments. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments based on the embodiments in the present invention, without any inventive work, will be apparent to those skilled in the art from the following description.
The invention is mainly characterized in that different calcination temperatures are selected according to different silicon contents to obtain modified TiO with proper specific surface area2。
Example 1:
after the first boiling of the hydrolysis procedure in the production of titanium dioxide by the sulfuric acid method is finished, the temperature is kept at 80-90 ℃. Uniformly and slowly adding according to SiO2The measured epoxy silane with the content of 3-4 percent is added for 30 min.
After the epoxy silane is added, starting steam to raise the temperature to 110 ℃ and keeping the micro-boiling state for 15-20min, then opening the steam flow to a small value, keeping the temperature at 80-90 ℃, and keeping the temperature for 4 h.
And (3) washing the hydrolyzed metatitanic acid twice, and squeezing by using a membrane filter press, wherein the water content of a filter cake after squeezing is about 50%.
And (3) delivering the filter cake into a rotary kiln for calcination, controlling the temperature of a first zone at 660-680 ℃, controlling the temperature of a kiln tail negative pressure tail at 100-150Pa, and calcining for 4h to obtain a crude product of TiO2 for the denitration catalyst.
Pulverizing the crude product with micropowder mill, and controlling particle size D50<1.1 and D90< 2.5. Packaging to obtain a finished product of TiO2 for the denitration catalyst.
By static N2 adsorptionThe BET of the finished product is detected to be 110.65m2/g。
Example 2: after the first boiling of the hydrolysis procedure in the production of titanium dioxide by the sulfuric acid method is finished, the temperature is kept at 80-90 ℃. Uniformly and slowly adding according to SiO24-5% of the metered epoxysilane, the addition time being 40 min.
After the epoxy silane is added, starting steam to raise the temperature to 110 ℃ and keeping the micro-boiling state for 15-20min, then opening the steam flow to a small value, keeping the temperature at 80-90 ℃, and keeping the temperature for 4 h.
And (3) washing the hydrolyzed metatitanic acid twice, and squeezing by using a membrane filter press, wherein the water content of a filter cake after squeezing is about 50%.
And (3) delivering the filter cake into a rotary kiln for calcination, controlling the temperature of a first zone at 680-700 ℃, the negative pressure of the kiln tail at 100-150Pa, and the calcination time at 4h to obtain a crude product of TiO2 for the denitration catalyst.
Pulverizing the crude product with micropowder mill, and controlling particle size D50<1.1 and D90< 2.5. Packaging to obtain a finished product of TiO2 for the denitration catalyst.
The BET of the finished product is 120.37m by a static N2 adsorption method2/g。
Example 3: after the first boiling of the hydrolysis procedure in the production of titanium dioxide by the sulfuric acid method is finished, the temperature is kept at 80-90 ℃. Uniformly and slowly adding according to SiO2The metered epoxy silane with the content of 5-7 percent is added for 50 min.
After the epoxy silane is added, starting steam to raise the temperature to 110 ℃ and keeping the micro-boiling state for 15-20min, then opening the steam flow to a small value, keeping the temperature at 80-90 ℃, and keeping the temperature for 4 h.
And (3) washing the hydrolyzed metatitanic acid twice, and squeezing by using a membrane filter press, wherein the water content of a filter cake after squeezing is about 50%.
The filter cake is sent into a rotary kiln for calcination, the temperature of one zone is controlled to be 700-2And (5) crude product.
Pulverizing the crude product with micropowder mill, and controlling particle size D50<1.1 and D90< 2.5. Packaging to obtain a finished product of TiO2 for the denitration catalyst.
By static stateBET of the finished product is 131.61m detected by an N2 adsorption method2/g。
Example 4: after the first boiling of the hydrolysis procedure in the production of titanium dioxide by the sulfuric acid method is finished, the temperature is kept at 80-90 ℃. Uniformly and slowly adding according to SiO2The measured epoxy silane with the content of 7-10 percent is added for 60 min.
After the epoxy silane is added, starting steam to raise the temperature to 110 ℃ and keeping the micro-boiling state for 15-20min, then opening the steam flow to a small value, keeping the temperature at 80-90 ℃, and keeping the temperature for 4 h.
And (3) washing the hydrolyzed metatitanic acid twice, and squeezing by using a membrane filter press, wherein the water content of a filter cake after squeezing is about 50%.
The filter cake is sent into a rotary kiln for calcination, the temperature of a first zone is controlled to be 730-2And (5) crude product.
Pulverizing the crude product with micropowder mill, and controlling particle size D50<1.1 and D90< 2.5. Packaging to obtain a finished product of TiO2 for the denitration catalyst.
The BET of the finished product is 148.52m by a static N2 adsorption method2/g。
Example 5: after the first boiling of the hydrolysis procedure in the production of titanium dioxide by the sulfuric acid method is finished, the temperature is kept at 80-90 ℃. Uniformly and slowly adding according to SiO2The metered epoxy silane with the content of 10-13 percent is added for 70 min.
After the epoxy silane is added, starting steam to raise the temperature to 110 ℃ and keeping the micro-boiling state for 15-20min, then opening the steam flow to a small value, keeping the temperature at 80-90 ℃, and keeping the temperature for 4 h.
And (3) washing the hydrolyzed metatitanic acid twice, and squeezing by using a membrane filter press, wherein the water content of a filter cake after squeezing is about 50%.
The filter cake is sent into a rotary kiln for calcination, the temperature of one zone is controlled to be 770-820 ℃, the negative pressure of the kiln tail is controlled to be 100-150Pa, and the calcination time is 4h, so that the TiO for the denitration catalyst is obtained2And (5) crude product.
Pulverizing the crude product with micronizer, controlling particle diameter D50<1.1，D90<2.5. Packaging to obtain TiO for denitration catalyst2And (5) finishing.
The BET of the finished product is 161.79m by a static N2 adsorption method2/g。
The product is mixed with TiO for common flue gas denitration catalyst2The thermal stability of the two materials is compared by detecting the change of the specific surface area of the materials after calcining for 2 hours at different temperatures.
It can be seen from the data in the table that the TiO for the denitration catalyst produced by this patent2The specific surface area is not obviously changed after the calcination for 2 hours at the temperature of 500 ℃ and 800 ℃, and the TiO for the common denitration catalyst2The specific surface area has obvious reduction tendency after calcining at 500-800 ℃ for 2 hours, and the thermal stability of the patented product is obviously superior to that of the conventional product.
Claims (3)
1. The preparation method of the high-temperature denitration catalyst carrier with high thermal stability is characterized by comprising the following steps: it comprises the following steps: (1) after the hydrolysis procedure of titanium dioxide production by sulfuric acid process is finished, keeping the temperature at 80-90 ℃, uniformly and slowly adding SiO2The measured epoxy silane with the content of 3 to 13 percent is added for 30 to 70 min; (2) after the epoxy silane is added, starting steam to raise the temperature to 105-110 ℃, keeping the micro-boiling state for 15-20min, then reducing the steam flow, keeping the temperature at 80-90 ℃, and preserving the heat for 4 h; (3) washing hydrolyzed metatitanic acid with water twice, squeezing by a membrane filter press, and obtaining a filter cake with water content of about 50% after squeezing; (4) the filter cake is sent into a rotary kiln for calcination, the temperature of one zone is controlled to be 660-class 820 ℃, the negative pressure of the kiln tail is controlled to be 100-class 150Pa, and the calcination time is 4h, so that the TiO for the denitration catalyst is obtained2A crude product; (5) pulverizing the crude product with a micro-powder mill, and controlling the particle size D50 after pulverizing<1.1，D90<2.5 packaging to obtain TiO for the denitration catalyst2And (5) finishing.
2. High temperature denitration catalyst carrier of thermal stability, characterized by: the preparation method of the high-temperature denitration catalyst carrier with high thermal stability of claim 1.
3. High temperature denitration catalyst of thermal stability, characterized by: it comprises the high-temperature denitration catalyst with high thermal stability of claim 2.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112717921A (en) * | 2020-09-01 | 2021-04-30 | 江苏峰业科技环保集团股份有限公司 | SCR denitration catalyst and preparation process thereof |
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| US20060083671A1 (en) * | 2004-10-14 | 2006-04-20 | Mitsubishi Heavy Industries, Ltd | Discharge gas treatment catalyst and method and apparatus for treating discharge gas |
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