Charcoal functional material, preparation method and application

Abstract

The invention discloses a biochar functional material. The biochar functional material comprises the following raw materials in percentage by mass: 50-70% of biochar and 30-50% of tar, the biochar is obtained by carbonizing one of pine wood or cedar wood in needlebush wood; the raw materials are mixed, dried and activated to obtain the charcoal functional material. The invention further discloses a preparation method of the biochar functional material and application of the biochar functional material in low-temperature NH3-SCR denitration. Compared with coal-based activated carbon, the prepared charcoal functional material has higher denitration efficiency and mechanical strength, and carbon dioxide emission is reduced.

Description

Technical Field

[0001] This invention belongs to the field of environmentally friendly functional material preparation and application technology, specifically relating to a method for preparing biochar functional materials using coniferous wood waste and its application in low-temperature NH3-SCR of flue gas. Background Technology

[0002] Nitrogen oxides (NOx) contained in flue gas emitted by industries such as steel and chemicals x This can lead to acid rain and smog, posing serious threats to the environment and human health. NH3-Selective Catalytic Reduction (NH3-SCR) is currently one of the most effective technologies for flue gas denitrification. Coal-based activated carbon has been applied in low-temperature flue gas denitrification, but the large-scale use of coal as a raw material results in high CO2 emissions.

[0003] Using carbon-neutral biomass to replace coal-based activated carbon in the preparation of SCR denitrification functional materials is beneficial for achieving pollution reduction, carbon reduction, and synergistic efficiency improvement. Previous studies on biochar preparation using biomass raw materials such as straw have been numerous, but they generally suffer from low mechanical strength. Compared to straw and other herbaceous plants, coniferous wood has a higher lignin content, suggesting that biochar functional materials with higher mechanical strength could potentially be prepared using coniferous wood as raw material. Currently, there are no reports on the preparation of biochar functional materials with certain mechanical strength from coniferous wood waste that can be used for low-temperature NH3-SCR denitrification. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to provide the biochar material. Another technical problem to be solved by the present invention is to provide a method for preparing biochar functional materials using coniferous wood. Yet another technical problem to be solved by the present invention is to provide the application of this material in low-temperature NH3-SCR denitrification of flue gas.

[0005] The technical solution of the present invention is a biochar functional material, wherein the raw material mass ratio of the functional material is: 50-70% biochar and 30-50% tar; the biochar is a type of coniferous wood, such as pine or cypress, obtained by carbonization; the above raw materials are mixed, dried and activated to obtain the biochar functional material.

[0006] Preferably, the coniferous wood is selected from coniferous waste pine wood.

[0007] This invention also provides a method for preparing the above-mentioned biochar functional material, the method comprising the following steps:

[0008] 1) Pretreatment: Pine or cypress waste from coniferous wood species is crushed to obtain wood powder;

[0009] 2) Carbonization: Pine or cypress powder from coniferous woods, or under N2 atmosphere or oxygen-deficient conditions, is heated to 500-800℃ at a programmed rate of 5-15℃ / min and carbonized for 30-90min. The carbonized material is then pulverized to prepare biochar powder.

[0010] 3) Mixing: The mass ratio of biochar powder to tar is 50-70% biochar and 30-50% tar.

[0011] 4) Granulation: Granulate the above mixture under a pressure of 0.5-5 MPa;

[0012] 5) Drying: Place the sample prepared in step 4) in an oven and dry at 50-100℃ for 4-12 hours;

[0013] 6) Activation: Heat to 600-980℃ at a rate of 5-15℃ / min, first activate in H2O atmosphere for 20-45min, then activate in CO2 atmosphere for 10-30min to prepare biochar functional materials.

[0014] Coniferous wood is a broad category, including pine, cypress, etc., which we previously referred to collectively as coniferous wood waste.

[0015] H2O and CO2 can directly contact biochar and undergo a series of chemical reactions, which helps to increase the specific surface area of ​​biochar and enrich the types and contents of functional groups on the surface of biochar, thereby improving denitrification performance.

[0016] According to the preparation method of biochar functional materials of the present invention, preferably, in step 1), the material is pulverized and then passed through a 60-100 mesh sieve; in step 2), the material is pulverized and then passed through an 80-150 mesh sieve. The initial raw materials are relatively coarse and do not need to be pulverized too finely. After carbonization, finer pulverization is required for uniform granulation.

[0017] According to the method for preparing biochar functional materials of the present invention, preferably, in the oxygen-deficient conditions described in step 2), the oxygen content is 2%-15% by volume. In step 6), the H2O content in the H2O atmosphere is 10-40%, and the CO2 content in the CO2 atmosphere is 5-20%.

[0018] Furthermore, in the anoxic conditions described in step 2), the oxygen content is 5%-15% by volume. More preferably, the oxygen content is 5%-15% by volume. Although increasing the oxygen content will cause a decrease in strength and an increase in loss, it will increase the denitrification performance.

[0019] According to the preparation method of biochar functional materials of the present invention, preferably, the granulation shape in step 4) is cylindrical particles. Because activated carbon granulators can only granulate into cylindrical particles, and long-term operation has verified that filling the denitrification tower with cylindrical granular activated carbon can meet the operational requirements, it is preferred to granulate to obtain cylindrical biochar particles. Granulation is necessary; powdered form will cause carbon powder agglomeration, increased temperature rise, and a risk of fire.

[0020] Furthermore, the granulation produces cylindrical samples with a diameter of 6-10 mm and a length of 5-12 mm. This process requires particles of a specific size, resulting in lower pressure loss within the tower and controlled energy consumption.

[0021] This invention also provides the application of the above-mentioned biochar functional material in low-temperature NH3 selective catalytic reduction denitrification of flue gas.

[0022] NH3-SCR refers to NH3 Selective Catalytic Reduction, which is one of the commonly used technologies in the field of flue gas denitrification.

[0023] According to the application of this invention, the denitrification reaction temperature is 50-150℃, the NO content is 200-600ppm, the NH3 content is 200-600ppm, the O2 content is 5-15%, and the volume hourly space velocity is 400-30000h. -1 .

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] The biochar functional material prepared by this invention has higher denitrification efficiency and mechanical strength compared with coal-based activated carbon (see Table 1). Moreover, because it uses carbon-neutral coniferous waste, it avoids high CO2 emissions compared with activated carbon prepared using coal.

[0026] Table 1 Comparison of performance indicators of denitrification functional materials

[0027]

[0028] Denitrification experimental conditions: reaction temperature 120℃, NO concentration 200ppm, NH3 concentration 200ppm, O2 content 5%, volume hourly space velocity 1500h⁻¹ -1 . Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the preparation process of the biochar functional material for low-temperature NH3-SCR denitrification according to the present invention. Detailed Implementation

[0030] To better understand the content of this invention, the following description, in conjunction with embodiments, further illustrates the invention. However, the examples given do not limit the scope of protection of this invention.

[0031] Example 1

[0032] (1) A biochar functional material for low-temperature NH3-SCR denitrification, the preparation steps of which are as follows:

[0033] 1) Pretreatment: Pine waste is crushed and passed through a 60-mesh sieve to obtain pine powder.

[0034] 2) Carbonization: Pine powder was heated to 600℃ at a rate of 5℃ / min under N2 atmosphere and carbonized for 60min; the carbonized material was crushed and passed through a 100-mesh sieve to prepare biochar powder.

[0035] 3) Mixing: The mass ratio of biochar powder to tar is 6:4.

[0036] 4) Granulation: The mixed material is granulated under a pressure of 2MPa to obtain a cylindrical sample with a diameter of 10mm and a length of 12mm.

[0037] 5) Drying: Place the cylindrical sample prepared in step 4) in an oven and dry at 80°C for 8 hours.

[0038] 6) Activation: The temperature was programmed to rise to 800℃ at a rate of 10℃ / min, and then activated for 40 min in an H2O atmosphere, followed by activation for 20 min in a CO2 atmosphere to prepare biochar functional materials. The H2O content in the atmosphere was 30%, and the CO2 content was 15%.

[0039] (2) Evaluation of SCR denitrification performance

[0040] The experimental conditions for SCR denitrification were set as follows: reaction temperature 50-150℃, NO concentration 200ppm, NH3 concentration 200ppm, O2 content 5%, and volume hourly space velocity (VHSV) 1500h. -1 The NO concentration was sampled and detected using a flue gas analyzer, and the denitrification efficiency was calculated. The compressive strength and abrasion resistance of the biochar functional material were tested using a compressive strength tester and an abrasion resistance tester, respectively. The experimental results are shown in Table 2.

[0041] Table 2 Denitrification efficiency and compressive and abrasion resistance values ​​of biochar functional materials

[0042]

[0043] The results in the table above show that biochar and tar can be used to prepare biochar functional materials through the method of the present invention. These materials can be used for low-temperature NH3-SCR denitrification and have high mechanical strength, meeting the application requirements for the strength of activated carbon functional materials in standards GB / T 7701.3-2008 and LY / T 3284-2021.

[0044] Example 2

[0045] (1) A biochar functional material for low-temperature NH3-SCR denitrification, the preparation steps of which are as follows:

[0046] 1) Pretreatment: Pine waste is crushed and passed through a 60-mesh sieve to obtain pine powder.

[0047] 2) Carbonization: Pine powder was heated to 500℃ at a rate of 5℃ / min under N2 atmosphere and carbonized for 40min; the carbonized material was crushed and passed through a 100-mesh sieve to prepare biochar powder.

[0048] 3) Mixing: The mass ratio of biochar powder to tar is 6:4.

[0049] 4) Granulation: The mixed material is granulated under a pressure of 2MPa to obtain a cylindrical sample with a diameter of 10mm and a length of 12mm.

[0050] 5) Drying: Place the cylindrical sample prepared in step 4) in an oven and dry at 80°C for 8 hours.

[0051] 6) Activation: The temperature was programmed to rise to 800℃ at a rate of 10℃ / min, and then activated for 40 min in an H2O atmosphere, followed by activation for 20 min in a CO2 atmosphere to prepare biochar functional materials. The H2O content in the atmosphere was 30%, and the CO2 content was 15%.

[0052] (2) Evaluation of SCR denitrification performance

[0053] The experimental conditions for SCR denitrification were set as follows: reaction temperature 50-150℃, NO concentration 200ppm, NH3 concentration 200ppm, O2 content 5%, and volume hourly space velocity (VHSV) 1500h. -1 The NO concentration was sampled and detected using a flue gas analyzer, and the denitrification efficiency was calculated. The compressive strength and abrasion resistance of the biochar functional material were tested using a compressive strength tester and an abrasion resistance tester, respectively. The experimental results are shown in Table 3.

[0054] Table 3. Denitrification efficiency and compressive and abrasion resistance values ​​of biochar functional materials.

[0055]

[0056] Compared with the biochar functional material in Example 1, the denitrification efficiency and pressure and wear resistance of the biochar functional material are slightly lower, indicating that controlling the carbonization conditions can regulate the denitrification efficiency and mechanical strength of the biochar functional material.

[0057] Example 3

[0058] (1) A biochar functional material for low-temperature NH3-SCR denitrification, the preparation steps of which are as follows:

[0059] 1) Pretreatment: Pine waste is crushed and passed through a 60-mesh sieve to obtain pine powder.

[0060] 2) Carbonization: Pine wood powder was heated to 600℃ at a rate of 5℃ / min under N2 atmosphere and carbonized for 60 min; the carbonized material was then pulverized through a 100-mesh sieve to prepare biochar powder. The coniferous waste material was pine wood.

[0061] 3) Mixing: The mass ratio of biochar powder to tar is 7:3.

[0062] 4) Granulation: The mixed material is granulated under a pressure of 2MPa to obtain a cylindrical sample with a diameter of 10mm and a length of 12mm.

[0063] 5) Drying: Place the cylindrical sample prepared in step 4) in an oven and dry at 80°C for 8 hours.

[0064] 6) Activation: The temperature was programmed to rise to 800℃ at a rate of 10℃ / min, and then activated for 40 min in an H2O atmosphere, followed by activation for 20 min in a CO2 atmosphere to prepare biochar functional materials. The H2O content in the atmosphere was 30%, and the CO2 content was 15%.

[0065] (2) Evaluation of SCR denitrification performance

[0066] The experimental conditions for SCR denitrification were set as follows: reaction temperature 50-150℃, NO concentration 200ppm, NH3 concentration 200ppm, O2 content 5%, and volume hourly space velocity (VHSV) 1500h. -1 The NO concentration was sampled and detected using a flue gas analyzer, and the denitrification efficiency was calculated. The compressive strength and abrasion resistance of the biochar functional material were tested using a compressive strength tester and an abrasion resistance tester, respectively. The experimental results are shown in Table 4.

[0067] Table 4. Denitrification efficiency and compressive and abrasion resistance values ​​of biochar functional materials.

[0068]

[0069] Compared with the biochar functional material in Example 1, the denitrification efficiency of the above table is not significantly different, but the pressure resistance and wear resistance are significantly reduced; indicating that controlling the amount of tar added is mainly beneficial to regulating the mechanical strength of the biochar functional material.

[0070] Example 4

[0071] (1) A biochar functional material for low-temperature NH3-SCR denitrification, the preparation steps of which are as follows:

[0072] 1) Pretreatment: Pine waste is crushed and passed through a 60-mesh sieve to obtain pine powder.

[0073] 2) Carbonization: Pine powder was heated to 600℃ at a rate of 5℃ / min under N2 atmosphere and carbonized for 60min; the carbonized material was crushed and passed through a 100-mesh sieve to prepare biochar powder.

[0074] 3) Mixing: The mass ratio of biochar powder to tar is 6:4.

[0075] 4) Granulation: The mixed material is granulated under a pressure of 2MPa to obtain a cylindrical sample with a diameter of 10mm and a length of 12mm.

[0076] 5) Drying: Place the cylindrical sample prepared in step 4) in an oven and dry at 80°C for 8 hours.

[0077] 6) Activation: The temperature was programmed to rise to 800℃ at a rate of 10℃ / min. Activation was first performed in an H2O atmosphere for 40 min, followed by activation in a CO2 atmosphere for 20 min to prepare the biochar functional material. The atmosphere contained 10% H2O and 5% CO2.

[0078] (2) Evaluation of SCR denitrification performance

[0079] The experimental conditions for SCR denitrification were set as follows: reaction temperature 50-150℃, NO concentration 200ppm, NH3 concentration 200ppm, O2 content 5%, and volume hourly space velocity (VHSV) 1500h. -1 The NO concentration was sampled and detected using a flue gas analyzer, and the denitrification efficiency was calculated. The compressive strength and abrasion resistance of the biochar functional material were tested using a compressive strength tester and an abrasion resistance tester, respectively. The experimental results are shown in Table 5.

[0080] Table 5. Denitrification efficiency and compressive and abrasion resistance values ​​of biochar functional materials.

[0081]

[0082] Compared with the biochar functional material in Example 1, the results in the table above show a decrease in denitrification efficiency and mechanical strength; indicating that controlling the activation atmosphere can regulate the denitrification efficiency and mechanical strength of the biochar functional material.

[0083] Example 5

[0084] (1) A biochar functional material for low-temperature NH3-SCR denitrification, the preparation steps of which are as follows:

[0085] 1) Pretreatment: Pine waste is crushed and passed through a 60-mesh sieve to obtain pine powder.

[0086] 2) Carbonization: Pine wood powder was heated to 600℃ at a rate of 5℃ / min under N2 atmosphere and carbonized for 60 min; the carbonized material was then pulverized through a 100-mesh sieve to prepare biochar powder. The coniferous waste material was pine wood.

[0087] 3) Mixing: The mass ratio of biochar powder to tar is 6:4.

[0088] 4) Granulation: The mixed material is granulated under a pressure of 2MPa to obtain a cylindrical sample with a diameter of 10mm and a length of 12mm.

[0089] 5) Drying: Place the cylindrical sample prepared in step 4) in an oven and dry at 80°C for 8 hours.

[0090] 6) Activation: The temperature was programmed to rise to 700℃ at a rate of 5℃ / min, and then activated for 30 min in an H2O atmosphere, followed by activation for 10 min in a CO2 atmosphere to prepare biochar functional materials. The H2O content in the atmosphere was 30%, and the CO2 content was 15%.

[0091] (2) Evaluation of SCR denitrification performance

[0092] The experimental conditions for SCR denitrification were set as follows: reaction temperature 50-150℃, NO concentration 200ppm, NH3 concentration 200ppm, O2 content 5%, and volume hourly space velocity (VHSV) 1500h. -1 The NO concentration was sampled and detected using a flue gas analyzer, and the denitrification efficiency was calculated. The compressive strength and abrasion resistance of the biochar functional material were tested using a compressive strength tester and an abrasion resistance tester, respectively. The experimental results are shown in Table 6.

[0093] Table 6. Denitrification efficiency and compressive and abrasion resistance values ​​of biochar functional materials.

[0094]

[0095] Compared with the biochar functional material in Example 1, the results in the table above show a decrease in denitrification efficiency and mechanical strength, indicating that controlling the activation temperature and time can regulate the denitrification efficiency and mechanical strength of the biochar functional material.

[0096] Example 6

[0097] (1) A biochar functional material for low-temperature NH3-SCR denitrification, the preparation steps of which are as follows:

[0098] 1) Pretreatment: The cypress waste is crushed and passed through a 60-mesh sieve to obtain cypress powder.

[0099] 2) Carbonization: Cypress powder was heated to 600℃ at a rate of 5℃ / min under an oxygen-deficient atmosphere and carbonized for 60 min; the carbonized material was then pulverized through a 100-mesh sieve to obtain biochar powder. The O2 content in the oxygen-deficient atmosphere was 9%.

[0100] 3) Mixing: The mass ratio of biochar powder to tar is 6:4.

[0101] 4) Granulation: The mixed material is granulated under a pressure of 2MPa to obtain a cylindrical sample with a diameter of 10mm and a length of 12mm.

[0102] 5) Drying: Place the cylindrical sample prepared in step 4) in an oven and dry at 80°C for 8 hours.

[0103] 6) Activation: The temperature was programmed to rise to 800℃ at a rate of 10℃ / min, and then activated for 40 min in an H2O atmosphere, followed by activation for 20 min in a CO2 atmosphere to prepare biochar functional materials. The H2O content in the atmosphere was 30%, and the CO2 content was 15%.

[0104] (2) Evaluation of SCR denitrification performance

[0105] The experimental conditions for SCR denitrification were set as follows: reaction temperature 50-150℃, NO concentration 200ppm, NH3 concentration 200ppm, O2 content 5%, and volume hourly space velocity (VHSV) 1500h. -1 The NO concentration was sampled and detected using a flue gas analyzer, and the denitrification efficiency was calculated. The compressive strength and abrasion resistance of the biochar functional material were tested using a compressive strength tester and an abrasion resistance tester, respectively. The experimental results are shown in Table 7.

[0106] Table 7 Denitrification efficiency and compressive and abrasion resistance values ​​of biochar functional materials

[0107]

[0108] The results in the table above show that biochar functional materials prepared from cypress wood (a type of coniferous wood) using the method of this invention can be used for low-temperature NH3-SCR denitrification and have high mechanical strength, meeting the application requirements for the strength of activated carbon functional materials in standards GB / T 7701.3-2008 and LY / T3284-2021.

[0109] Comparative Example 1

[0110] Only the pine waste described in this application is added, and the material is processed according to the pretreatment, carbonization, mixing, granulation, drying, and activation conditions of Example 1.

[0111] Comparative Example 2

[0112] Only one type of commercial coal-based activated carbon is used.

[0113] Comparative Example 3

[0114] Only one type of commercial coconut shell-based activated carbon is used.

[0115] The activated carbon functional materials obtained above were all tested under the SCR denitrification experimental conditions of Example 1. The denitrification efficiency results are shown in Table 8, and the strength results are shown in Table 9.

[0116] Table 8 Comparison of denitrification efficiency between comparative examples and Example 1

[0117]

[0118] Table 9 Comparison of intensity values ​​between the comparative example and Example 1

[0119]

[0120]

[0121] The results in the table above show that the biochar functional material prepared by this invention has higher denitrification efficiency at lower temperatures (50-150℃) compared with other denitrification functional materials, and also has higher mechanical strength, which can meet the requirements of the application strength standards for activated carbon functional materials (GB / T 7701.3-2008 and LY / T 3284-2021).

Claims

1. A biochar functional material, characterized in that: The raw material mass ratio of this functional material is: 50-70% biochar and 30-50% tar; the biochar is a type of coniferous wood, such as pine or cypress, obtained by carbonization; the above raw materials are mixed, dried, and activated to obtain the biochar functional material.

2. The biochar functional material according to claim 1, characterized in that: The coniferous wood is selected from coniferous waste pine wood.

3. The method for preparing the biochar functional material according to claim 1, characterized in that: The method includes the following steps: 1) Pretreatment: Pine or cypress waste from coniferous wood species is crushed to obtain wood powder; 2) Carbonization: Pine or cypress powder from coniferous woods, or under N2 atmosphere or oxygen-deficient conditions, is heated to 500-800℃ at a programmed rate of 5-15℃ / min and carbonized for 30-90min. The carbonized material is then pulverized to prepare biochar powder. 3) Mixing: The mass ratio of biochar powder to tar is 50-70% biochar and 30-50% tar. 4) Granulation: Granulate the above mixture under a pressure of 0.5-5 MPa; 5) Drying: Place the sample prepared in step 4) in an oven and dry at 50-100℃ for 4-12 hours; 6) Activation: Heat to 600-980℃ at a rate of 5-15℃ / min, first activate in H2O atmosphere for 20-45min, then activate in CO2 atmosphere for 10-30min to prepare biochar functional materials.

4. The method for preparing biochar functional materials according to claim 3, characterized in that: Step 1) involves pulverizing the material and then passing it through a 60-100 mesh sieve; Step 2) involves pulverizing the material and then passing it through an 80-150 mesh sieve.

5. The method for preparing biochar functional materials according to claim 3, characterized in that: In step 2), the oxygen content in the oxygen-deficient conditions is 2%-15% by volume; in step 6), the H2O content in the H2O atmosphere is 10-40%, and the CO2 content in the CO2 atmosphere is 5-20%.

6. The method for preparing biochar functional materials according to claim 5, characterized in that: In step 2), the oxygen content under the hypoxic conditions is 5%-15% by volume.

7. The method for preparing biochar functional materials according to claim 3, characterized in that: Step 4) The granulation shape is cylindrical particles.

8. The method for preparing biochar functional materials according to claim 7, characterized in that: The granulation process produces cylindrical samples with a diameter of 6-10 mm and a length of 5-12 mm.

9. The application of the biochar functional material according to claim 1 in low-temperature NH3 selective catalytic reduction denitrification of flue gas.

10. The application according to claim 9, characterized in that: The denitrification reaction temperature is 50-150℃, the NO content is 200-600ppm, the NH3 content is 200-600ppm, the O2 content is 5-15%, and the volume hourly space velocity is 400-30000h. -1 .

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