A composite adsorption catalyst for removing sulfur dioxide from flue gas and its preparation process

Abstract

The present invention discloses a composite adsorption catalyst for removing sulfur dioxide from flue gas and its preparation process. By weight, the raw materials for preparing the composite adsorption catalyst include: 40 - 60 parts of modified activated carbon; 10 - 30 parts of alkaline auxiliary filler; 5 - 10 parts of binder. Among them, the modified activated carbon is obtained by treating composite activated carbon with nitrogen plasma, and the raw materials for preparing the composite activated carbon include 60 - 80wt% coconut shell fiber powder, 10 - 18wt% attapulgite clay, and 8 - 25wt% modified wood fossil powder. In the composite adsorption catalyst of the present invention, the modified activated carbon is obtained by treating composite activated carbon with nitrogen plasma, so that a large number of nitrogen-containing basic functional groups such as amino groups are introduced onto the surface of the activated carbon, and the pore size distribution and pore structure are improved, providing more adsorption sites, thereby enhancing the overall adsorption capacity and adsorption rate of the catalyst, reducing the regeneration frequency, and reducing the production cost.

Description

Technical Field

[0001] The invention relates to the technical field of flue gas treatment, and in particular to a composite adsorption catalyst for removing sulfur dioxide from flue gas and a preparation process thereof. Background Art

[0002] Sulfur dioxide in flue gas is one of the main sources of air pollution. It reacts with water vapor and oxygen in the air to form sulfuric acid and sulfates, which in turn lead to the formation of acid rain. Acid rain has caused serious harm to the environment and ecosystem, such as soil acidification, water pollution, plant death, etc. Through flue gas desulfurization technology, sulfur dioxide emissions can be effectively reduced, thereby protecting the environment and ecosystem.

[0003] At present, flue gas desulfurization technology is mainly divided into wet desulfurization and dry desulfurization. In dry desulfurization, the flue gas passes through the alkaline absorbent bed or is sprayed into the flue gas flow, and contacts with the solid alkaline adsorption catalyst (such as activated carbon, metal oxides, etc.), so that sulfur dioxide reacts directly with the solid alkaline substance to generate the corresponding sulfite and sulfate. Therefore, these adsorption catalysts play a key role in the desulfurization process, which can accelerate the oxidation reaction of sulfur dioxide and improve the desulfurization efficiency.

[0004] However, existing activated carbon-based adsorption catalysts have the following defects: (1) The adsorption capacity is limited and they often have to operate at low gas velocities, which results in a larger adsorber volume; (2) During the removal process, the activated carbon loses its activity due to clogging of the surface micropores, so it needs to be regenerated frequently, resulting in low treatment efficiency and high treatment costs. Summary of the invention

[0005] The purpose of the present invention is to provide a composite adsorption catalyst for removing sulfur dioxide from flue gas and a preparation process thereof, which solves the problems of low treatment efficiency and high treatment cost caused by the limited adsorption capacity of the existing activated carbon adsorption catalyst, which requires operation at a low gas velocity and requires frequent regeneration treatment.

[0006] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0007] A composite adsorption catalyst for removing sulfur dioxide from flue gas, wherein the raw materials for preparing the composite adsorption catalyst include, by weight:

[0008] 40-60 parts of modified activated carbon;

[0009] 10-30 parts of alkaline auxiliary filler;

[0010] 5-10 parts of adhesive;

[0011] Among them, the modified activated carbon is obtained by subjecting composite activated carbon to nitrogen plasma treatment, and the preparation raw materials of the composite activated carbon include 60 - 80 wt% coconut shell fiber powder, 10 - 18 wt% attapulgite clay, and 8 - 25 wt% modified wood fossil powder.

[0012] Preferably, the modified wood fossil powder is obtained by subjecting wood fossil powder to swelling treatment and etherification treatment.

[0013] Preferably, the alkaline auxiliary filler is selected from one or more of fly ash, mica powder, feldspar powder, and slaked lime.

[0014] Preferably, the binder is selected from one or more of polyvinyl alcohol, polypropylene, and carboxymethyl cellulose.

[0015] The present invention also provides a preparation process for the composite adsorption catalyst for removing sulfur dioxide from flue gas, and the steps include:

[0016] S1. Prepare modified wood fossil powder, and then proportionally take dry coconut shell fiber powder, attapulgite clay, and modified wood fossil powder and mix them evenly through a high-speed mixer to obtain a mixture. Take the mixture and subject it to granulation, carbonization, and activation to obtain composite activated carbon;

[0017] S2. Take the composite activated carbon and subject it to nitrogen plasma treatment to obtain modified activated carbon;

[0018] S3. Proportionally take the modified activated carbon, alkaline auxiliary filler, and binder and mix them evenly through a high-speed mixer to obtain a catalyst preliminarily prepared;

[0019] S4. Take the catalyst preliminarily prepared and press it into shape, dry it, sinter it, naturally cool it, and package it to obtain the composite adsorption catalyst.

[0020] Preferably, in step S1, the preparation method of the modified wood fossil powder is as follows:

[0021] (1) Swelling treatment: Take wood fossil powder, disperse it in a polyethylene glycol aqueous solution with a mass 5 - 8 times and a concentration of 0.5 - 2 mg / mL, control the temperature at 50 - 60 °C, and react at a stirring rate of 20 - 40 r / min for 6 - 12 h. After the reaction is completed, filter, and take the obtained wood fossil powder and wash and dry it;

[0022] (2) Etherification treatment: Take the wood fossil powder after swelling treatment, disperse it in a sodium hydroxide aqueous solution with a mass 5 - 8 times and a mass fraction of 10 - 15%, control the temperature to 70 - 80 °C, then add sodium chloroacetate accounting for 3 - 6% of the mass of the wood fossil powder and react for 3 - 5 h. After the reaction is completed, adjust the pH to neutral with acetic acid, and finally filter, and take the obtained wood fossil powder and wash and dry it to obtain the modified wood fossil powder.

[0023] Preferably, in step S1, the granulation refers to making particles with a size of 1 - 3 mm using a granulator, the carbonization refers to carbonizing at 500 - 600 °C for 1 - 2 h in a carbonization furnace, and the activation refers to activating at 800 - 1000 °C for 8 - 16 h in an activation furnace.

[0024] Preferably, in step S2, the discharge voltage of the nitrogen plasma treatment is 10 kV - 30 kV, the treatment time is 20 - 40 min, and the flow rate of the nitrogen gas source is 60 - 100 sccm.

[0025] Preferably, in step S4, the sintering refers to in a sintering furnace, under an inert atmosphere, controlling the heating rate at 2 - 3 °C / min to raise the furnace temperature to 200 - 250 °C, and keeping it warm for 1 - 2 h.

[0026] The beneficial effects of the present invention are as follows:

[0027] (1) In the composite adsorption catalyst of the present invention, the modified activated carbon is obtained by subjecting the composite activated carbon to nitrogen plasma treatment. This introduces a large number of nitrogen - containing basic functional groups such as amino groups on the surface of the activated carbon, improves the pore size distribution and pore structure, provides more adsorption sites, thereby enhancing the overall adsorption capacity and adsorption rate of the catalyst, reducing the regeneration frequency, and decreasing the production cost.

[0028] (2) The composite activated carbon used in the present invention is added with modified wood fossil powder, which can increase the structural strength and stability of the activated carbon. At the same time, it disperses and homogenizes the etching points during plasma treatment, thus reducing the phenomenon of partial micropore blockage or collapse on the surface of the activated carbon caused by plasma treatment, avoiding the loss of specific surface area, and further enhancing the adsorption performance of the activated carbon.

[0029] (3) The modified wood fossil powder used in the present invention is obtained by swelling treatment and etherification treatment of wood fossil powder. Among them, the etherification treatment can react with the hydroxyl groups of the small amount of remaining xylem in the wood fossil to form new ether bonds, thereby improving the compatibility and adhesion of the overall wood fossil powder with coconut shell fiber powder, and further enhancing the strength stability of the activated carbon; the previous swelling treatment can increase the permeability of the wood fossil, expose the xylem hydroxyl groups as much as possible, and ensure the progress of the etherification reaction. Description of the Drawings

[0030] Figure 1 It is the SEM image of the modified activated carbon obtained by subjecting the present invention to nitrogen plasma treatment. Detailed Embodiments

[0031] The present application will be further described in detail below with reference to the accompanying drawings. It is necessary to point out here that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the protection scope of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0032] I. Main raw materials and equipment:

[0033] Coconut shell fiber powder: Mature coconut shells (from Hainan Province, China) are soaked in water for degumming to separate the fibers from the coconut shells. Then, the coconut shells are beaten, and the coconut husk in the fibers is removed using a roller wire drawing machine. Impurities and short fibers are also removed. Finally, the coconut shell fibers are obtained through drying. The coconut shell fibers are crushed, classified, and sieved to obtain coconut shell fiber powder with a particle size of 10 - 50 μm.

[0034] Attapulgite clay: Purchased from Hebei Guanting Building Materials Technology Co., Ltd., with a particle size of 0.1 - 1 μm.

[0035] Fossil wood powder: Mainly trunk fossil wood, purchased from the fossil wood market in Ruili City, Yunnan Province. Through infrared spectrum analysis, its main chemical composition is SiO 2 and Al 2 O 3 , as well as a small amount of remaining wood fiber structure. The fossil wood is crushed and sieved to obtain fossil wood powder with a particle size of 5 - 20 μm.

[0036] Scanning electron microscope: S - 4800 type scanner produced by Hitachi, Ltd., Japan.

[0037] Plasma treatment equipment: CTP - 2000K type plasma processor produced by Nanjing Suman Plasma Technology Co., Ltd.

[0038] Specific surface area analysis equipment: Nova 4000e type specific surface area and pore structure analyzer produced by Quantachrome Corporation, USA.

[0039] II. Specific implementation experiments

[0040] Example 1: A composite adsorption catalyst for removing sulfur dioxide from flue gas. By weight, the preparation raw materials of the composite adsorption catalyst include: 40 parts of modified activated carbon, 10 parts of fly ash, and 5 parts of polyvinyl alcohol (here, PVA2699 is used). Among them, the modified activated carbon is obtained by treating composite activated carbon with nitrogen plasma, and the preparation raw materials of the composite activated carbon include 80 wt% of coconut shell fiber powder with a particle size of 10 ± 2 μm, 12 wt% of attapulgite clay with a particle size of 0.2 ± 0.01 μm, and 8 wt% of modified fossil wood powder with a particle size of 5 ± 1 μm; the modified fossil wood powder is obtained by swelling treatment and etherification treatment of fossil wood powder.

[0041] The preparation process of the composite adsorption catalyst for removing sulfur dioxide from flue gas includes the following steps:

[0042] S1. Prepare modified wood fossil powder. Then, take dry coconut shell fiber powder, attapulgite clay, and modified wood fossil powder in proportion, mix them evenly in a high-speed mixer to obtain a mixture. Take the mixture and make it into 1-mm particles with a granulator. Then, carbonize the particles in a carbonization furnace at 500 °C for 2 h, and finally activate them with steam at 800 °C in an activation furnace for 16 h to obtain composite activated carbon.

[0043] Among them, the preparation method of the modified wood fossil powder is as follows:

[0044] (1) Swelling treatment: Take wood fossil powder, disperse it in an aqueous polyethylene glycol solution with a mass 5 times that of the powder and a concentration of 2 mg / mL (the polyethylene glycol used is PEG-800), control the temperature at 50 °C, and react at a stirring rate of 20 r / min for 12 h. After the reaction is completed, filter, and take the filtered wood fossil powder, wash it, and dry it.

[0045] (2) Etherification treatment: Take the wood fossil powder after swelling treatment, disperse it in an aqueous sodium hydroxide solution with a mass 5 times that of the powder and a mass fraction of 15%, control the temperature to 70 °C, then add sodium chloroacetate accounting for 3% of the mass of the wood fossil powder and react for 5 h. After the reaction is completed, adjust the pH to neutral with acetic acid, finally filter, take the filtered wood fossil powder, wash it repeatedly with clear water, and then dry it with a dryer to obtain the modified wood fossil powder.

[0046] S2. Take the obtained composite activated carbon and perform nitrogen plasma treatment on it to obtain modified activated carbon. Among them, the discharge voltage of the nitrogen plasma treatment is 10 kV, the treatment time is 40 min, and the flow rate of the nitrogen gas source is 100 sccm.

[0047] S3. Take the modified activated carbon, fly ash, and polyvinyl alcohol in proportion, mix them evenly in a high-speed mixer to obtain the initial catalyst material.

[0048] S4. Take the initial catalyst material, press it into a column shape, dry it in a drying oven, sinter it (in a sintering furnace, control the heating rate at 2 °C / min in an inert atmosphere to raise the furnace temperature to 200 °C and keep it warm for 2 h), cool it naturally, and package it to obtain the composite adsorption catalyst.

[0049] Example 2: A composite adsorption catalyst for removing sulfur dioxide from flue gas. By weight, the raw materials for preparing the composite adsorption catalyst include: 50 parts of modified activated carbon, 20 parts of muscovite powder (800 mesh), and 8 parts of polypropylene (maleic anhydride grafted polypropylene PP18729 is used here). Among them, the modified activated carbon is obtained by treating composite activated carbon with nitrogen plasma, and the raw materials for preparing the composite activated carbon include 70 wt% of coconut shell fiber powder with a particle size of 30 ± 2 μm, 15 wt% of attapulgite clay with a particle size of 0.5 ± 0.1 μm, and 15 wt% of modified wood fossil powder with a particle size of 15 ± 1 μm; the modified wood fossil powder is obtained by swelling treatment and etherification treatment of wood fossil powder.

[0050] The preparation process of the composite adsorption catalyst for removing sulfur dioxide from flue gas includes the following steps:

[0051] S1. Prepare the modified wood fossil powder. Then, take dry coconut shell fiber powder, attapulgite clay, and modified wood fossil powder in proportion, mix them evenly in a high-speed mixer to obtain a mixture. Take the mixture and make it into 2-mm particles with a granulator, then carbonize them in a carbonization furnace at 550 °C for 1.5 h, and finally activate them with steam in an activation furnace at 900 °C for 12 h to obtain composite activated carbon.

[0052] Among them, the preparation method of the modified wood fossil powder is as follows:

[0053] (1) Swelling treatment: Take wood fossil powder, disperse it in a polyethylene glycol aqueous solution with a mass 6 times and a concentration of 1 mg / mL (PEG-800 is used for polyethylene glycol), control the temperature at 55 °C, and react at a stirring rate of 30 r / min for 9 h. After the reaction is completed, filter, and take the filtered wood fossil powder, wash it, and dry it.

[0054] (2) Etherification treatment: Take the wood fossil powder after swelling treatment, disperse it in a sodium hydroxide aqueous solution with a mass 6 times and a mass fraction of 12%, control the temperature to 75 °C, then add sodium chloroacetate accounting for 5% of the mass of the wood fossil powder and react for 4 h. After the reaction is completed, adjust the pH to neutral with acetic acid, finally filter, take the filtered wood fossil powder, wash it repeatedly with clear water, and then dry it with a dryer to obtain the modified wood fossil powder.

[0055] S2. Take the composite activated carbon and perform nitrogen plasma treatment on it to obtain modified activated carbon; among them, the discharge voltage of the nitrogen plasma treatment is 20 kV, the treatment time is 30 min, and the flow rate of the nitrogen gas source is 80 sccm.

[0056] S3. Take the modified activated carbon, muscovite powder, and polypropylene in proportion, mix them evenly in a high-speed mixer to obtain the initial catalyst.

[0057] S4. Take the initial catalyst material, press it into a columnar shape, dry it in a drying oven, sinter it (in a sintering furnace, control the heating rate at 2.5 °C / min in an inert atmosphere to raise the furnace temperature to 220 °C and keep it warm for 1.5 h), cool it naturally, and package it to obtain the composite adsorption catalyst.

[0058] Example 3: A composite adsorption catalyst for removing sulfur dioxide from flue gas. By weight, the raw materials for preparing the composite adsorption catalyst include: 60 parts of modified activated carbon, 30 parts of feldspar powder (JYOR-16 is used here), and 10 parts of carboxymethyl cellulose. Among them, the modified activated carbon is obtained by treating the composite activated carbon with nitrogen plasma, and the raw materials for preparing the composite activated carbon include 60 wt% of coconut shell fiber powder with a particle size of 50 ± 2 μm, 15 wt% of attapulgite clay with a particle size of 1 ± 0.1 μm, and 25 wt% of modified wood fossil powder with a particle size of 20 ± 1 μm; the modified wood fossil powder is obtained by swelling treatment and etherification treatment of wood fossil powder.

[0059] The preparation process of the composite adsorption catalyst for removing sulfur dioxide from flue gas includes the following steps:

[0060] S1. Prepare the modified wood fossil powder, then take the dried coconut shell fiber powder, attapulgite clay, and modified wood fossil powder in proportion, mix them evenly in a high-speed mixer to obtain a mixture, make the mixture into 3-mm particles with a granulator, then carbonize them at 600 °C in a carbonization furnace for 1 h, and finally activate them with steam at 1000 °C in an activation furnace for 8 h to obtain the composite activated carbon.

[0061] Among them, the preparation method of the modified wood fossil powder is as follows:

[0062] (1) Swelling treatment: Take the wood fossil powder, disperse it in an aqueous solution of polyethylene glycol with 8 times the mass and a concentration of 0.5 mg / mL (PEG-800 is used for polyethylene glycol), control the temperature at 60 °C, and react at a stirring rate of 40 r / min for 6 h. After the reaction is completed, filter it, and take the filtered wood fossil powder, wash it, and dry it.

[0063] (2) Etherification treatment: Take the wood fossil powder after swelling treatment, disperse it in an aqueous solution of sodium hydroxide with 8 times the mass and a mass fraction of 10%, control the temperature to 80 °C, then add sodium chloroacetate accounting for 6% of the mass of the wood fossil powder and react for 3 h. After the reaction is completed, adjust the pH to neutral with acetic acid, finally filter it, take the filtered wood fossil powder, wash it repeatedly with water, and then dry it with a dryer to obtain the modified wood fossil powder.

[0064] S2. Take the composite activated carbon, perform nitrogen plasma treatment on it to obtain the modified activated carbon, and scan its surface morphology with an S-4800 type scanner as Figure 1As shown, it can be seen that the surface of the activated carbon is rich in a large number of micropores, and the pore structure is complete, with basically no collapse and blockage; among them, the discharge voltage for nitrogen plasma treatment is 30 kV, the treatment time is 20 min, and the flow rate of the nitrogen gas source is 100 sccm.

[0065] S3. Take the modified activated carbon, feldspar powder, and carboxymethyl cellulose in proportion and mix them evenly in a high-speed mixer to obtain the initial catalyst material.

[0066] S4. Take the initial catalyst material, press it into a column shape, dry it in a drying oven, sinter it (in a sintering furnace, control the heating rate at 3 °C / min in an inert atmosphere to raise the furnace temperature to 250 °C and keep it warm for 1 h), cool it naturally, and package it to obtain the composite adsorption catalyst.

[0067] Comparative Example 1: A composite adsorption catalyst for removing sulfur dioxide from flue gas. By weight, the preparation raw materials of the composite adsorption catalyst include: 60 parts of modified activated carbon, 30 parts of feldspar powder (JYOR-16 is used here), and 10 parts of carboxymethyl cellulose. Among them, the modified activated carbon is obtained by nitrogen plasma treatment of activated carbon, and the preparation raw material of the activated carbon is coconut shell fiber powder with a particle size of 50 ± 2 μm.

[0068] The preparation process of the composite adsorption catalyst for removing sulfur dioxide from flue gas includes the following steps:

[0069] S1. Take the dry coconut shell fiber powder and make it into 3-mm particles with a granulator, then carbonize it at 600 °C in a carbonization furnace for 1 h, and finally activate it with steam at 1000 °C in an activation furnace for 8 h to obtain activated carbon.

[0070] S2. Take the activated carbon and perform nitrogen plasma treatment on it to obtain modified activated carbon; among them, the discharge voltage for nitrogen plasma treatment is 30 kV, the treatment time is 20 min, and the flow rate of the nitrogen gas source is 100 sccm.

[0071] S3. Take the modified activated carbon, feldspar powder, and carboxymethyl cellulose in proportion and mix them evenly in a high-speed mixer to obtain the initial catalyst material.

[0072] S4. Take the initial catalyst material, press it into a column shape, dry it in a drying oven, sinter it (in a sintering furnace, control the heating rate at 3 °C / min in an inert atmosphere to raise the furnace temperature to 250 °C and keep it warm for 1 h), cool it naturally, and package it to obtain the composite adsorption catalyst.

[0073] Comparative Example 2: A composite adsorption catalyst for removing sulfur dioxide from flue gas. By weight, the raw materials for preparing the composite adsorption catalyst include: 60 parts of modified activated carbon, 30 parts of feldspar powder (here JYOR-16 is used), and 10 parts of carboxymethyl cellulose. Among them, the modified activated carbon is obtained by treating composite activated carbon with nitrogen plasma, and the raw materials for preparing the composite activated carbon include 60 wt% of coconut shell fiber powder with a particle size of 50 ± 2 μm, 15 wt% of attapulgite clay with a particle size of 1 ± 0.1 μm, and 25 wt% of silicified wood powder with a particle size of 20 ± 1 μm.

[0074] The preparation process of the composite adsorption catalyst for removing sulfur dioxide from flue gas includes the following steps:

[0075] S1. Take dry coconut shell fiber powder, attapulgite clay, and silicified wood powder in proportion, mix them evenly in a high-speed mixer to obtain a mixture. Take the mixture and make it into 3-mm particles with a granulator, then carbonize it at 600 °C in a carbonization furnace for 1 h, and finally activate it with steam at 1000 °C in an activation furnace for 8 h to obtain composite activated carbon.

[0076] S2. Take the composite activated carbon and perform nitrogen plasma treatment on it to obtain modified activated carbon. Among them, the discharge voltage of the nitrogen plasma treatment is 30 kV, the treatment time is 20 min, and the flow rate of the nitrogen gas source is 100 sccm.

[0077] S3. Take the modified activated carbon, feldspar powder, and carboxymethyl cellulose in proportion, and mix them evenly in a high-speed mixer to obtain the initial catalyst.

[0078] S4. Take the initial catalyst, press it into a column shape, dry it in a drying oven, sinter it (in a sintering furnace, under an inert atmosphere, control the heating rate at 3 °C / min to raise the furnace temperature to 250 °C and keep it for 1 h), cool it naturally, and package it to obtain the composite adsorption catalyst.

[0079] Comparative Example 3: A composite adsorption catalyst for removing sulfur dioxide from flue gas. By weight, the raw materials for preparing the composite adsorption catalyst include: 60 parts of modified activated carbon, 30 parts of feldspar powder (here JYOR-16 is used), and 10 parts of carboxymethyl cellulose. Among them, the modified activated carbon is obtained by treating composite activated carbon with nitrogen plasma, and the raw materials for preparing the composite activated carbon include 60 wt% of coconut shell fiber powder with a particle size of 50 ± 2 μm, 15 wt% of attapulgite clay with a particle size of 1 ± 0.1 μm, and 25 wt% of modified silicified wood powder; the modified silicified wood powder is obtained by etherification treatment of silicified wood powder.

[0080] The preparation process of the composite adsorption catalyst for removing sulfur dioxide from flue gas includes the following steps:

[0081] S1. Prepare modified wood fossil powder. Then, take dry coconut shell fiber powder, attapulgite clay, and modified wood fossil powder in proportion and mix them evenly in a high-speed mixer to obtain a mixture. Take the mixture and make 3-mm particles with a granulator. Then, carbonize the particles in a carbonization furnace at 600 °C for 1 h, and finally activate them with steam at 1000 °C in an activation furnace for 8 h to obtain composite activated carbon.

[0082] Among them, the preparation method of the modified wood fossil powder is as follows: Etherification treatment: Take wood fossil powder, disperse it in an aqueous sodium hydroxide solution with 8 times the mass and a mass fraction of 10%, control the temperature to 80 °C, then add sodium chloroacetate accounting for 6% of the mass of the wood fossil powder and react for 3 h. After the reaction is completed, adjust the pH to neutral with acetic acid, and finally filter. Take the filtered wood fossil powder, wash it repeatedly with clear water, and then dry it with a dryer to obtain the modified wood fossil powder.

[0083] S2. Take the obtained composite activated carbon and perform nitrogen plasma treatment on it to obtain modified activated carbon; among them, the discharge voltage of the nitrogen plasma treatment is 30 kV, the treatment time is 20 min, and the flow rate of the nitrogen gas source is 100 sccm.

[0084] S3. Take the modified activated carbon, feldspar powder, and carboxymethyl cellulose in proportion and mix them evenly in a high-speed mixer to obtain the initial catalyst material.

[0085] S4. Take the initial catalyst material, press it into a column shape, dry it in a drying oven, sinter it (in a sintering furnace, control the heating rate at 3 °C / min in an inert atmosphere to raise the furnace temperature to 250 °C and keep it warm for 1 h), cool it naturally, and package it to obtain the composite adsorption catalyst.

[0086] III. Performance Testing

[0087] Take the modified activated carbon and the final composite adsorption catalyst prepared in Examples 1-3 and Comparative Examples 1-3 above and conduct the following performance tests:

[0088] (1) Specific surface area: Take the modified activated carbon samples of each experimental group and use a Nova 4000e type specific surface area and pore structure analyzer to detect their specific surface areas respectively.

[0089] (2) Strength stability: Take the modified activated carbon samples of each experimental group and refer to the standard of GB / T12496.6-1999 "Test Methods for Wood Activated Carbon - Determination of Strength" to test their abrasion resistance (%) respectively.

[0090] (3) Sulfur dioxide removal performance: Take the composite adsorption catalyst samples of each experimental group, first perform degassing pretreatment on them (degas at 90 °C for 20 min and then at 200 °C for 2 h), and then refer to the standard of GB / T7702.14-1997 "Test Methods for Coal-based Granular Activated Carbon - Determination of Saturated Sulfur Capacity" to test their saturated sulfur capacity respectively.

[0091] IV. Test Results and Analysis

[0092] (1) Specific surface area:

[0093] Table 1: Specific surface area test results of each experimental group

[0094]

[0095] (2) Strength stability:

[0096] Table 2: Abrasion resistance strength test results of each experimental group

[0097]

[0098] (3) Sulfur dioxide removal performance:

[0099] Table 3: Saturated sulfur capacity test results of each experimental group

[0100]

[0101] It can be seen from Tables 1 - 3 that the modified activated carbon used in Examples 1 - 3 of the present invention has a large specific surface area, high strength and excellent desulfurization performance. Among them, the highest specific surface area reaches 1221.2 m 2 / g, the highest abrasion resistance strength reaches 99.1%, and the highest saturated sulfur capacity reaches 1403.4 mg / g.

[0102] Comparative Examples 1 - 3 were all adjusted on the basis of Example 3, among which:

[0103] In Comparative Example 1, all the raw materials used in the preparation of activated carbon were coconut shell fiber powder, without using modified wood fossil powder, resulting in a significant decrease in its specific surface area and saturated sulfur capacity compared with Example 3, and the abrasion resistance strength also decreased significantly. This shows that the addition of modified wood fossil powder plays an important role in maintaining the specific surface area and increasing the strength stability during the nitrogen plasma treatment process.

[0104] In Comparative Example 2, unmodified ordinary wood fossil powder was added to the raw materials during the preparation of activated carbon. Its specific surface area and saturated sulfur capacity were improved compared with Comparative Example 2, but still significantly inferior to Example 3, indicating that the modification process can improve the overall compatibility and adhesion of wood fossil powder with coconut shell fiber powder, and further enhance the strength stability of activated carbon.

[0105] In Comparative Example 3, modified wood fossil powder (but only etherification treatment was carried out, without the previous swelling treatment) was added to the raw materials during the preparation of activated carbon. Its specific surface area and saturated sulfur capacity were not significantly improved compared with Comparative Example 2, indicating that only by carrying out etherification treatment, the etherification reaction cannot proceed effectively, which may be related to the dense structure of wood fossil.

[0106] The embodiments described above merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention.

Claims

1. A composite adsorption catalyst for removing sulfur dioxide from flue gas, characterized in that: The raw materials for preparing the composite adsorption catalyst include, by weight: 40-60 parts of modified activated carbon; 10-30 parts of alkaline auxiliary filler; Adhesive 5-10 parts; The modified activated carbon is obtained by treating composite activated carbon with nitrogen plasma, and the raw materials for preparing the composite activated carbon include 60-80wt% coconut shell fiber powder, 10-18wt% attapulgite clay and 8-25wt% modified petrified wood powder, and the modified petrified wood powder is obtained by treating petrified wood powder with swelling and etherification.

2. The composite adsorption catalyst for removing sulfur dioxide from flue gas according to claim 1, characterized in that: The alkaline auxiliary filler is selected from one or more of fly ash, mica powder, feldspar powder and slaked lime.

3. The composite adsorption catalyst for removing sulfur dioxide from flue gas according to claim 1, characterized in that: The adhesive is selected from one or more of polyvinyl alcohol, polypropylene, and carboxymethyl cellulose.

4. A process for preparing a composite adsorption catalyst for removing sulfur dioxide from flue gas as claimed in any one of claims 1 to 3, characterized in that the steps include: S1, preparing modified wood fossil powder, and then taking dry coconut fiber powder, attapulgite clay, and modified wood fossil powder in proportion and mixing them evenly with a high-speed mixer to obtain a mixture, and taking the mixture and granulating, carbonizing, and activating it to obtain composite activated carbon; The preparation method of the modified wood fossil powder is: (1) Swelling treatment: Take petrified wood powder and disperse it in a polyethylene glycol aqueous solution with a concentration of 0.5-2 mg / mL and a mass of 5-8 times, control the temperature to 50-60°C, and react at a stirring rate of 20-40 r / min for 6-12 hours. After the reaction is completed, filter and wash and dry the petrified wood powder obtained by filtration; (2) Etherification treatment: Take the petrified wood powder after swelling treatment, disperse it in a sodium hydroxide aqueous solution with a mass fraction of 5-8 times and 10-15%, control the temperature to 70-80°C, then add sodium chloroacetate with a mass fraction of 3-6% of the petrified wood powder for reaction for 3-5 hours, adjust the pH to neutral with acetic acid after the reaction, filter, wash and dry the filtered petrified wood powder, and obtain the modified petrified wood powder; S2, taking the composite activated carbon and subjecting it to nitrogen plasma treatment to obtain modified activated carbon; S3, taking the modified activated carbon, alkaline auxiliary filler and adhesive in proportion and mixing them evenly with a high-speed stirrer to obtain a catalyst initial material; S4, taking the catalyst raw material, performing compression molding, drying, sintering, natural cooling, and packaging to obtain a composite adsorption catalyst.

5. The preparation process of the composite adsorption catalyst for removing sulfur dioxide from flue gas according to claim 4, characterized in that: In step S1, the granulation refers to using a granulator to form particles of 1-3 mm, the carbonization refers to carbonization at 500-600° C. in a carbonization furnace for 1-2 hours, and the activation refers to activation at 800-1000° C. in an activation furnace for 8-16 hours.

6. The preparation process of the composite adsorption catalyst for removing sulfur dioxide from flue gas according to claim 4, characterized in that: In step S2, the discharge voltage of the nitrogen plasma treatment is 10 kV-30 kV, the treatment time is 20-40 min, and the flow rate of the source nitrogen is 60-100 sccm.

7. The preparation process of the composite adsorption catalyst for removing sulfur dioxide from flue gas according to claim 4, characterized in that: In step S4, the sintering refers to controlling the heating rate of 2-3°C / min in a sintering furnace under an inert atmosphere to raise the temperature in the furnace to 200-250°C, and keeping the temperature for 1-2h.

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