CN105457627B - A kind of glass fabric Supported Manganese base low temperature SCR denitration catalyst and preparation method thereof - Google Patents

Abstract

The invention discloses a method for preparing a manganese-based low-temperature SCR denitrification catalyst loaded on glass fiber cloth, including pretreatment of glass fiber cloth, and loading the manganese-based low-temperature SCR denitrification catalyst on the glass fiber cloth by using low-temperature glue for loading manganese-based catalysts for low-temperature denitrification The above process, heat treatment and infrared irradiation treatment, etc. The glass fiber cloth loaded manganese-based low-temperature SCR denitrification catalyst prepared by the present invention not only retains the characteristics of good insulation of glass fiber, strong heat resistance, good corrosion resistance and high mechanical strength, but also the catalyst in the prepared material is loaded on glass fiber Uniformity, good firmness, good denitrification performance (up to 98%) under low temperature conditions (80-180° C.), and broad application prospects.

Description

A glass fiber cloth-loaded manganese-based low-temperature SCR denitrification catalyst and its preparation method

technical field

The invention belongs to the field of industrial waste gas treatment and environmental protection catalytic materials, and in particular relates to a manganese-based low-temperature SCR denitrification catalyst supported by glass fiber cloth and a preparation method thereof.

Background technique

Nitrogen oxides (NO _x ) can not only lead to the formation of acid rain, but also react with ozone to form photochemical smog. At present, photochemical smog has become an important air pollutant after inhalable particulate matter and sulfur dioxide. It is worth noting that with the increase of _NOx emissions year by year, the trend of regional acid deposition is deteriorating, secondary particulate matter ozone (O ₃ ) and fine inhalable particulate matter (PM 2.5) in the atmosphere are high and difficult, and human health and ecological environment are affected. a huge threat. The control and treatment of nitrogen oxides is imperative.

Among many denitrification technologies, selective catalytic reduction (selective catalytic reduction, SCR) is a more promising denitrification technology. This technology refers to the selective catalytic reduction of NO _x to N ₂ and H ₂ O by using a reducing agent (such as NH ₃ , H ₂ , CO or hydrocarbons, etc.) in the presence of a catalyst and oxygen. The core of SCR denitration technology is the SCR denitration catalyst. According to the needs of industrial temperature, it can be divided into medium and high temperature SCR denitration catalysts and low temperature SCR denitration catalysts. Among them, the SCR low-temperature denitrification catalyst with an applicable temperature range of less than 200 ° C has been extensively studied because of its good economic and social benefits. At present, manganese and its oxides are widely used and studied for the active components of SCR low-temperature denitrification catalysts. .

The carrier can make the catalyst have suitable shape, size and mechanical strength to meet the operating requirements of industrial reactors; the carrier can disperse the active components on the surface of the carrier to obtain a higher specific surface area and increase the active mass per unit mass. points of catalytic efficiency. Therefore, SCR low-temperature denitrification catalysts are often supported on specific carriers. Common carriers include titanium dioxide, alumina, silica gel, zirconia, ceria, activated carbon, and some natural products such as pumice, diatomaceous earth, etc. These commonly used supports usually have a large specific surface area and good thermal stability, which can promote the catalytic reaction and prevent the sintering of the catalyst. _In addition, some carriers have some special properties: CeO2 has a good oxygen storage function when used as a carrier, thereby promoting the catalytic reaction; molecular sieves have ion exchange properties, uniform molecular size pores, acid catalytic activity, and good Excellent thermal stability and hydrothermal stability can be made into catalysts with high activity and high selectivity for many reactions.

At present, the loading methods of manganese-based SCR low-temperature denitration catalysts mainly include impregnation method, coating method, hydrothermal synthesis method, etc. The impregnation method is a loading method that has been adopted so far because of its advantages such as simple operation steps, short preparation cycle, safety and energy saving. However, due to the inhomogeneous loading of the catalyst in the prepared sample and the poor firmness, it is difficult to be applied in the actual industrial production with complex environment, so this method is currently limited to laboratory preparation.

Contents of the invention

The purpose of the present invention is to provide a manganese-based low-temperature SCR denitration catalyst loaded on glass fiber cloth and its preparation method. The method is simple and easy to operate, and can solve the problem of uneven loading and poor firmness of the manganese-based low-temperature SCR denitrification catalyst in the load. And other issues, suitable for promotion and application.

To achieve the above object, the technical solution adopted in the present invention is:

A method for preparing a manganese-based low-temperature SCR denitration catalyst supported by glass fiber cloth, comprising the following steps:

1) Cut the glass fiber cloth into a certain size and shape according to the actual use, soak it in soapy water, wash and dry it; then put it in hydrochloric acid solution for corrosion treatment, and obtain the pretreated glass fiber cloth, dry it and weigh it After weighing, let it stand for later use;

2) Stir and mix the low-temperature denitrification manganese-based catalyst-loaded low-temperature glue and the manganese-based low-temperature SCR denitrification catalyst evenly, and set aside for later use;

3) Spread the pretreated glass fiber cloth obtained in step 1) on the stainless steel workbench, and use a spraying machine to evenly coat the low-temperature glue and manganese-based low-temperature SCR denitration catalyst in step 2) on the obtained product in step 1). Put it on the pretreated glass fiber cloth, and place it in an oven to dry;

4) placing the material obtained in step 3) in a muffle furnace for heat treatment, and cooling to obtain a glass fiber cloth loaded with a manganese-based low-temperature SCR denitration catalyst;

5) The glass fiber cloth loaded with the manganese-based low-temperature SCR denitration catalyst obtained in step 4) is subjected to infrared irradiation treatment to obtain the glass fiber cloth-loaded manganese-based low-temperature SCR denitration catalyst.

In the above scheme, the soaking time in soapy water described in step 1) is 20 to 60 minutes.

In the above solution, the concentration of the hydrochloric acid solution in step 1) is 1-3 mol/L, and the corrosion treatment time is 20-60 min.

In the above scheme, the ratio of the volume of the low-temperature gel for supporting the low-temperature denitration manganese-based catalyst in step 2) to the mass of the manganese-based SCR low-temperature denitration catalyst is (2-10):1.

In the above solution, the coating thickness in step 3) is 0.2-1.2 mm.

In the above solution, the heat treatment step in step 4) is: heating to 200-400° C. for 2-6 hours.

In the above scheme, the infrared light band selected in the infrared irradiation treatment in step 5) is the mid-infrared band (2.5-25 μm), and the treatment time is 10-30 min.

In the above scheme, the preparation method of the low-temperature gel for low-temperature denitrification manganese-based catalyst loading is as follows: 1) adding absolute ethanol, water, isopropanol, tetraethyl orthosilicate, catechol and formaldehyde aqueous solution in sequence, and continuously Stir and ultrasonically disperse to obtain a uniform mixed solution I; 2) Slowly add strong acid to the obtained mixed solution I to adjust the pH value to 2-4 to obtain a mixed solution II, which is simultaneously stirred and ultrasonically dispersed; 3) Mixed solution II Heating to 70-90°C, and carrying out constant temperature stirring reaction for 2-8 hours, until a viscous transparent colloid is obtained, which is the low-temperature glue for supporting low-temperature denitrification manganese-based catalysts.

In the above scheme, the volume ratio of the absolute ethanol, water, tetraethyl orthosilicate and Virahol is (3～8):1:(2～4):(0.05～0.1); The volume ratio of formaldehyde solution is (1~1.2):1; the volume ratio of tetraethyl orthosilicate to formaldehyde solution is (20~60):1; the strong acid is hydrochloric acid or nitric acid, the concentration is 1~3mol/L.

In the above scheme, the manganese-based low-temperature SCR denitration catalyst in step 2) is MnO _x (non-supported), MnO _x /TiO ₂ (supported) or Cu-MnO _x /TiO ₂ (supported) type low-temperature SCR denitration The catalyst, wherein the form of MnO _x is one or more of MnO ₂ , Mn ₂ O ₃ , and Mn ₃ O ₄ .

The manganese-based low-temperature SCR denitration catalyst supported on glass fiber cloth prepared according to the above scheme has a denitration efficiency of 98% under the conditions of a temperature range of 80-180°C and a space velocity of 20000-30000h ^-1 .

The beneficial effects of the present invention are:

1) Glass fiber cloth has the characteristics of stable physical and chemical properties, good insulation, strong heat resistance, good corrosion resistance and high mechanical strength. Using glass fiber cloth to load manganese-based low-temperature SCR denitrification catalyst can prolong the service life of the catalyst and improve the performance of the catalyst. Mechanical strength, and effectively reduce production costs. At the same time, the glass fiber cloth plays the role of denitrification while making the flue gas filtering structure.

2) In the present invention, the manganese-based low-temperature SCR denitration catalyst is loaded on the surface of glass fiber cloth by using low-temperature adhesive for low-temperature denitrification manganese-based catalyst prepared by hydrolysis synthesis method, and the catalyst in the prepared material is evenly loaded on the glass fiber cloth, firm It has good denitrification performance and good denitrification performance.

3) By infrared treatment of the prepared catalytic material, not only the firmness between the catalyst and the glass fiber cloth can be improved, but also the activity of the catalyst sample and its denitrification efficiency can be improved.

detailed description

In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with the examples, but the present invention is not limited to the following examples.

The following examples are not specifically described, and the reagents used are commercially available chemical reagents or industrial products.

In the following examples, the preparation method of the low-temperature gel for low-temperature denitrification manganese-based catalyst loading is as follows: 1) sequentially mix 30ml of absolute ethanol, 10ml of deionized water, 0.5ml of isopropanol, 20ml of tetraethyl orthosilicate, o-benzene Add diphenol and formaldehyde (wherein the volume ratio of catechol and formaldehyde aqueous solution is 1:1, and the total volume of the two is 1ml) into a three-necked flask, continuously stir and ultrasonically disperse for 30min to obtain a uniform mixed solution I; 2) Slowly add hydrochloric acid solution (concentration: 1mol/L) to the obtained mixed solution I, adjust the pH value to 2 to obtain the mixed solution II, and simultaneously stir and ultrasonically disperse for 10 minutes; 3) Mix the mixed solution II with 3 Heat to 70°C at a rate of °C/min, and carry out a constant temperature stirring reaction for 8 hours to obtain a viscous transparent colloid (there is wall hanging in the beaker), which is the low-temperature glue for supporting low-temperature denitrification manganese-based catalysts.

The manganese-based low-temperature SCR denitration catalyst adopted in the following examples is a non-supported MnO _x low-temperature SCR denitration catalyst, and its preparation method comprises the following steps: 1) Potassium permanganate and manganese acetate are dissolved respectively with a molar ratio of 1:2 in distilled water; 2) Slowly add the obtained manganese acetate solution into the potassium permanganate solution and fully stir, after 10 minutes of reaction, suction filtration and ultrasonic washing are performed until the filtrate is neutral; 3) After drying the precipitate in an oven, place Heat it in a muffle furnace to 400°C and roast for 3 hours, and grind it thoroughly to get a non-supported MnO _x low-temperature SCR denitration catalyst (its main component is MnO ₂ , and there are a small amount of Mn ₂ O ₃ and Mn ₃ O ₄ ).

Example 1

A method for preparing a manganese-based low-temperature SCR denitration catalyst supported by glass fiber cloth, comprising the following steps:

1) Cut the glass fiber cloth into a certain size and shape according to the actual use, soak it in soapy water, wash and dry it, and then corrode it in 1mol/L hydrochloric acid for 20 minutes to obtain the pretreated glass fiber cloth, dry it and After weighing, put it aside for later use;

2) Put the low-temperature glue for low-temperature denitrification manganese-based catalyst loading and the manganese-based low-temperature SCR denitration catalyst into the container at a ratio of 2:1 between the volume of the low-temperature glue and the mass of the manganese-based low-temperature SCR denitration catalyst, and stir with a stirring bar to mix Evenly, stand for later use;

3) Spread the pretreated glass fiber cloth obtained in step 1) on a stainless steel workbench, and use a sprayer to evenly coat the low-temperature glue and manganese-based low-temperature SCR denitration catalyst mixed uniformly in step 2) on the pretreated On glass fiber cloth, the coating thickness is 0.2mm, and placed in an oven to dry;

4) placing the material obtained in step 3) in a muffle furnace for heat treatment, the heat treatment temperature is 200° C., and the time is 2 hours. After cooling, a glass fiber cloth loaded with a manganese-based low-temperature SCR denitration catalyst is obtained;

5) The glass fiber cloth loaded with the manganese-based low-temperature SCR denitration catalyst obtained in step 4) is subjected to infrared irradiation treatment, the selected infrared light band is the mid-infrared band (2.5-25 μm), and the treatment time is 10 minutes to obtain the glass fiber Cloth-loaded manganese-based low-temperature SCR denitration catalyst.

The product obtained in this example was placed in a fixed-bed quartz tube reactor for denitration performance test. The simulated flue gas was composed of N ₂ , O ₂ , NO, and NH ₃ , where NO was 720 ppm, NH ₃ was 800 ppm, and O ₂ was the volume When the fraction is 3%, N ₂ is used as the balance gas; the test temperature range is 80-180°C, and the space velocity is 30000h ^-1 . The test results show that: with the increase of the test temperature, the denitrification efficiency gradually increases, and the average denitrification efficiency can reach 70%. Among them, the denitrification rate is 53% at 100°C, 72% at 120°C, above 80% at 120°C, and the highest at 180°C, reaching 86%.

Example 2

A method for preparing a manganese-based low-temperature SCR denitration catalyst supported by glass fiber cloth, comprising the following steps:

1) Cut the glass fiber cloth into a certain size and shape according to the actual use, soak it in soapy water, wash and dry it, and then corrode it in 2mol/L hydrochloric acid for 30 minutes to obtain the pretreated glass fiber cloth, dry it and After weighing, put it aside for later use;

2) Put the low-temperature gel for low-temperature denitrification manganese-based catalyst loading and the manganese-based low-temperature SCR denitrification catalyst into the container at a ratio of 4:1 between the volume of the low-temperature gel and the mass of the manganese-based low-temperature SCR denitrification catalyst, and stir with a stirring bar to mix Evenly, stand for later use;

3) Spread the pretreated glass fiber cloth obtained in step 1) on a stainless steel workbench, and use a sprayer to evenly coat the low-temperature glue and manganese-based low-temperature SCR denitration catalyst mixed uniformly in step 2) on the pretreated On glass fiber cloth, the coating thickness is 0.4mm, and placed in an oven to dry;

4) placing the material obtained in step 3) in a muffle furnace for heat treatment, the heat treatment temperature is 300° C., and the time is 3 hours. After cooling, a glass fiber cloth loaded with a manganese-based low-temperature SCR denitration catalyst is obtained;

5) The glass fiber cloth loaded with the manganese-based low-temperature SCR denitration catalyst obtained in step 4) is subjected to infrared irradiation treatment, the selected infrared light band is the mid-infrared band (2.5-25 μm), and the treatment time is 20 minutes to obtain the glass fiber cloth Cloth-loaded manganese-based low-temperature SCR denitration catalyst.

The product obtained in this example was placed in a fixed-bed quartz tube reactor for denitration performance test. The simulated flue gas was composed of N ₂ , O ₂ , NO, and NH ₃ , where NO was 720 ppm, NH ₃ was 800 ppm, and O ₂ was the volume The fraction is 3%, and N ₂ is used as the balance gas; the test temperature range is 80-180°C, and the space velocity is 25000h ^-1 . The test results show that: with the increase of the test temperature, the denitrification efficiency gradually increases, and the average denitrification efficiency can reach 90%. Among them, the denitrification rate is 75% at 100°C, above 90% at higher than 100°C, and the highest at 180°C, reaching 98%.

Example 3

A method for preparing a manganese-based low-temperature SCR denitration catalyst supported by glass fiber cloth, comprising the following steps:

1) Cut the glass fiber cloth into a certain size and shape according to the actual use, soak it in soapy water, wash and dry it, and then corrode it in 3mol/L hydrochloric acid for 40min to obtain the pretreated glass fiber cloth, dry it and After weighing, put it aside for later use;

2) Put the low-temperature gel for low-temperature denitrification manganese-based catalyst loading and the manganese-based low-temperature SCR denitrification catalyst into the container at a ratio of 8:1 between the volume of the low-temperature gel and the mass of the manganese-based low-temperature SCR denitrification catalyst, and stir with a stirring bar to mix Evenly, stand for later use;

3) Spread the pretreated glass fiber cloth obtained in step 1) on a stainless steel workbench, and use a sprayer to evenly coat the low-temperature glue and manganese-based low-temperature SCR denitration catalyst mixed uniformly in step 2) on the pretreated On glass fiber cloth, the coating thickness is 1.0mm, and placed in an oven to dry;

4) placing the material obtained in step 3) in a muffle furnace for heat treatment, the heat treatment temperature is 400° C., and the time is 4 hours. After cooling, a glass fiber cloth loaded with a manganese-based low-temperature SCR denitration catalyst is obtained;

5) The glass fiber cloth loaded with the manganese-based low-temperature SCR denitration catalyst obtained in step 4) is subjected to infrared irradiation treatment, the selected infrared light band is the mid-infrared band (2.5-25 μm), and the treatment time is 30 minutes to obtain the glass fiber cloth Cloth-loaded manganese-based low-temperature SCR denitration catalyst.

The product obtained in this example was placed in a fixed-bed quartz tube reactor for denitration performance test. The simulated flue gas was composed of N ₂ , O ₂ , NO, and NH ₃ , where NO was 720 ppm, NH ₃ was 800 ppm, and O ₂ was the volume The fraction is 3%, N ₂ is used as the balance gas; the test temperature range is 80-180°C, and the space velocity is 20000h ^-1 . The test results show that: with the increase of the test temperature, the denitrification efficiency gradually increases, and the average denitrification efficiency can reach 80%. Among them, the denitrification rate is 69% at 100°C, 76% at 120°C, and reaches the highest at 88% at 180°C.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the creative concept of the present invention, some improvements and changes are made, and these all belong to the protection of the present invention. scope.

Claims (9)

1. A preparation method of glass fiber cloth loaded manganese-based low-temperature SCR denitrification catalyst, characterized in that, comprising the following steps: 1) Soak the glass fiber cloth in soapy water, wash it, dry it, and then place it in a hydrochloric acid solution for corrosion treatment to obtain the pretreated glass fiber cloth. After drying and weighing, let it stand for later use; 2) Stir and mix the low-temperature denitrification manganese-based catalyst-loaded low-temperature glue and the manganese-based low-temperature SCR denitrification catalyst evenly, and set aside for later use; 3) uniformly coating the low-temperature glue and the manganese-based low-temperature SCR denitration catalyst in step 2) on the pretreated glass fiber cloth obtained in step 1), and drying in an oven; 4) placing the material obtained in step 3) in a muffle furnace for heat treatment, and cooling to obtain a glass fiber cloth loaded with a manganese-based low-temperature SCR denitration catalyst; 5) subjecting the glass fiber cloth loaded with manganese-based low-temperature SCR denitration catalyst obtained in step 4) to infrared irradiation treatment to obtain the glass fiber cloth-loaded manganese-based low-temperature SCR denitration catalyst; The preparation method of the low-temperature glue for supporting low-temperature denitrification manganese-based catalysts is as follows: 1) sequentially add absolute ethanol, water, isopropanol, tetraethyl orthosilicate, catechol and formaldehyde aqueous solution, continuously stir and ultrasonically disperse , to obtain a uniform mixed solution I; 2) slowly add a strong acid to the obtained mixed solution I, adjust the pH value to 2 to 4, to obtain a mixed solution II, and simultaneously stir and ultrasonically disperse; 3) heat the mixed solution II to 70 ～90°C, and carry out constant temperature stirring reaction for 2～8 hours to obtain a viscous transparent colloid, which is the low-temperature glue for supporting low-temperature denitrification manganese-based catalysts. 2. The preparation method according to claim 1, characterized in that the concentration of the hydrochloric acid solution in step 1) is 1-3 mol/L, and the corrosion treatment time is 20-60 min. 3. The preparation method according to claim 1, characterized in that, in step 2), the ratio of the volume of the low-temperature gel for loading the low-temperature denitrification manganese-based catalyst to the mass of the manganese-based SCR low-temperature denitration catalyst is (2-10) :1. 4. The preparation method according to claim 1, characterized in that the coating thickness in step 3) is 0.2-1.2 mm. 5. The preparation method according to claim 1, characterized in that, the heat treatment step in step 4) is: heating to 200-400° C. for 2-6 hours. 6. The preparation method according to claim 1, characterized in that, the infrared light band selected in the infrared irradiation treatment in step 5) is a mid-infrared band, and the treatment time is 10-30 minutes. 7. preparation method according to claim 1, is characterized in that, the volume ratio of described dehydrated alcohol, water, tetraethyl orthosilicate and Virahol is (3～8):1:(2～4) : (0.05～0.1); the volume ratio of catechol and formaldehyde solution is (1～1.2):1; the volume ratio of tetraethyl orthosilicate and formaldehyde solution is (20～60):1; the strong acid is hydrochloric acid or Nitric acid, the concentration is 1~3mol/L. 8. The preparation method according to claim 1, characterized in that, the manganese-based low-temperature SCR denitration catalyst described in step 2) is MnO _x , MnO _x /TiO ₂ or Cu-MnO _x /TiO ₂ low-temperature SCR denitration catalyst, The existing form of MnO _x is one or more of MnO ₂ , Mn ₂ O ₃ , and Mn ₃ O ₄ . 9. The manganese-based low-temperature SCR denitration catalyst supported by glass fiber cloth prepared according to the preparation method described in any one of claims 1-8.