Preparation method of iron oxide-loaded activated carbon by recycling biomass gasification residues

Abstract

A preparation method of iron oxide-loaded activated carbon by recycling biomass gasification residues belongs to the field of biomass gasification residues, and comprises the following steps: reacting biomass gasification residues with alkali, and separating to obtain a waste liquid containing silicon, aluminum, calcium and phosphorus and a carbon residue solid containing an iron oxide component; introducing greenhouse gas carbon dioxide discharged by a thermal power plant into the alkali liquor to obtain a silicon-containing solid sample and waste liquid containing aluminum, sodium and phosphorus, preparing sodium silicate and an inorganic silicon chemical product from the silicon-containing solid sample, and preparing a potassium-based compound fertilizer from the waste liquid to be used in the field of agricultural production; and activating the iron oxide-containing carbon residue solid at high temperature, soaking in a ferric chloride solution, and carrying out high-temperature treatment to obtain the iron oxide-loaded activated carbon. According to the invention, the compound fertilizer, the related inorganic silicon compound and the high-quality activated carbon product are prepared by processing with a relatively simple process and a relatively low production cost, so that not only is the problem of stacking pollution of the biomass gasification residues solved, but also the application additional value of the biomass gasification residues is greatly improved, and the industrial development of biomass energy is promoted.

Description

Technical Field

[0001] This invention belongs to the technical field of treatment and utilization of various components of biomass gasification residue, and particularly relates to a method for preparing supported iron oxide activated carbon for the reuse of biomass gasification residue. Background Technology

[0002] As global climate change poses a significant threat to human society, an increasing number of countries are elevating "carbon neutrality" to a national strategy, proposing a vision of a carbon-free future. Pursuing a low-carbon path means striving to achieve carbon emission reduction targets at the lowest possible cost while maintaining the overall goals of economic and social development. A low-carbon economy and green growth will become major trends in future economic development. Therefore, the gasification and utilization of biomass and its byproducts is precisely based on this goal.

[0003] Biomass gasification is a renewable energy technology used to produce fuel gas, heat, electricity, or biomass fuel. my country possesses vast biomass resources, providing a solid foundation for the development of biomass gasification technology. During gasification, biomass materials undergo pyrolysis and chemical reactions under high temperature and pressure, producing gases (mainly syngas, including carbon monoxide and hydrogen), liquid fuels (bio-oil), and residues. These residues typically include ash, waste residue, or solid waste, known as biomass gasification residues. The large-scale accumulation of these biomass residues as industrial waste not only occupies significant amounts of land but also poses potential environmental hazards due to the heavy metals and other harmful substances they contain. Therefore, the resource utilization of biomass gasification residues is of significant practical importance.

[0004] Biomass residue is mainly composed of silicon dioxide and carbon, with a small amount of metals and ash. Numerous institutions and individuals both domestically and internationally have conducted extensive research and development on the comprehensive utilization of biomass residue, and have achieved some progress. For example, CN103332994A discloses a method and system for the comprehensive utilization of biomass ash residue, achieving comprehensive utilization through acid washing, alkali washing, and activation reactions, thus solving the problem of biomass ash residue disposal. However, this method cannot effectively utilize the greenhouse gas carbon dioxide emitted by thermal power plants, thereby reducing greenhouse gas emissions, and the activated carbon prepared by this method has a low adsorption rate. CN201110436706.9 discloses a simple method for simultaneously preparing water glass and activated carbon from rice husk pyrolysis ash. This method improves the activated carbon yield, is simple in process, and has low energy consumption, but the raw material is limited to rice husk, limiting its applicability. Publication No. CN201110382347.3 discloses a method for preparing non-fired building materials using straw ash, which involves reacting straw ash with cement, quicklime, and gypsum to produce the building materials. This method eliminates the pollution caused by straw ash to the environment around power plants and reduces the production cost of the building materials. However, its application is limited to the construction sector, and the collection and transportation distance restricts its market application. Publication No. CN102515156A discloses a new method for preparing silica and activated carbon using rice husk ash. The preparation process does not generate waste gas or waste residue, but the preparation cost is relatively high. Publication No. CN111774029A discloses the preparation of PM2.5 using biomass ash. 2.5 Methods for preparing adsorbents, their products, and applications; this method yields PM with resistance to high-temperature sintering and strong fuel adaptability. 2.5 While the paper describes an adsorbent, it does not address silicon, the main component of rice husk ash, thus failing to fully utilize biomass ash. Publication number CN115739203A discloses a method for preparing supported iron oxide activated carbon based on the reuse of gasification slag. This method solves the problem of high production costs for supported iron oxide activated carbon and promotes the recycling of solid waste resources. However, this method uses waste residue generated during coal gasification as raw material and does not address the utilization of biomass gasification residue. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method for preparing supported iron oxide activated carbon for the reuse of biomass gasification residue.

[0006] The technical solution adopted in this invention is: a method for preparing supported iron oxide activated carbon for the reuse of biomass gasification residue, the key technical points of which include the following steps: Step 1: Dry and grind the biomass gasification residue into fine powder to obtain 400-600 mesh biomass solid residue; add 2-5 mol / L alkaline solution to the biomass solid residue, stir and mix, and heat. After reaction, separate the solid and liquid to obtain waste liquid containing silicon, aluminum, sodium, calcium, and phosphorus, and residual carbon solid containing iron oxide; place the residual carbon solid in an oven, control the temperature at 100℃-110℃, and dry for 12-15 hours to obtain residual carbon solid material with a moisture content of no more than 5%; Step 2: Slowly pass carbon dioxide, a greenhouse gas emitted from a thermal power plant, into the waste liquid containing silicon, aluminum, calcium, and sodium from Step 1 until the pH reaches 9-11. At this point, the system is in a sol state. Then, slowly add flocculant at a mass ratio of 1:40 to 1:100 to the waste liquid. Stir continuously until a large amount of white flocculent precipitate is suddenly produced. Filter and wash thoroughly until the filter cake is neutral to obtain a solid sample containing silicon precipitate and waste liquid containing aluminum, sodium, and phosphorus. The silicon-containing precipitate solid samples are used to produce sodium silicate and inorganic silicon chemical products; the waste liquid containing aluminum, sodium and phosphorus is used to produce potassium-based compound fertilizer. Step 3: The residual carbon solid containing iron oxide from Step 1 is fed into a tube furnace for high-temperature activation. During the activation process, nitrogen is used as an inert protective gas and water vapor is used as an activating agent. Water vapor is continuously introduced into the tube furnace at a flow rate of 0.2-0.66 L / min. The heating rate of the tube furnace is controlled at 15-22℃ / min, and the temperature is raised to 800-950℃. The activation time is 1-3 hours to obtain activated carbon. The activated carbon was then soaked in a 2-5 mol / L metal salt solution for 20-24 hours, removed, and dried at 80-120℃ for 10-15 hours to obtain metal activated carbon. Nitrogen was used as an inert protective gas to treat the loaded metal activated carbon at high temperature. After the nitrogen was filled, heating was started, and the heating temperature was controlled at 350-550℃ with a heating rate of 15-22℃ / min. The holding temperature was controlled at 400-500℃ for 3-5 hours. After the reaction was completed, the carbon was cooled to room temperature to obtain activated carbon loaded with metal oxide.

[0007] Furthermore, in step one, the biomass gasification slag grinding equipment adopts a vertical planetary ball mill with a rotation speed of 200-400 r / min, clockwise rotation for 10-20 min, counterclockwise rotation for 10-20 min, rotation reversal interval of 0-2 min, and a total ball milling time of 3-4 h.

[0008] Furthermore, the alkaline solution is selected from one or a combination of potassium hydroxide and sodium hydroxide solutions, and the reaction time is optimal to ensure sufficient reaction with the silicon, aluminum, calcium and sodium elements in the biomass ash.

[0009] Furthermore, the biomass gasification residue mentioned in step one is one or a mixture of two or more of the following: straw residue, wheat straw residue, forest wood residue, fruit shell residue, and vegetable waste pyrolysis residue.

[0010] Furthermore, in step two, the flocculant is one of the inorganic ammonium salts of ammonium sulfate, ammonium chloride, and ammonium phosphate.

[0011] Furthermore, the nitrogen protective gas is introduced throughout the entire process of heating, heat preservation, and cooling in the high-temperature treatment.

[0012] Furthermore, in step three, the metal salt solution is selected from either ferric chloride or ferric sulfate solution. The beneficial effects of this invention are as follows: The method for preparing iron oxide-loaded activated carbon for the reuse of biomass gasification residue uses biomass gasification residue as raw material. The biomass gasification residue is reacted with alkali to separate alkaline solution containing silicon, aluminum, calcium, phosphorus, etc., and solid carbon residue containing iron oxide. Carbon dioxide, a greenhouse gas discharged from a thermal power plant, is passed into the alkaline solution to separate silicon-containing solid samples and waste liquid containing aluminum, phosphorus, etc. The silicon-containing solid is used to produce sodium silicate and inorganic silicon chemical products, and the aluminum, sodium, phosphorus, etc. waste liquid is used to produce potassium-based compound fertilizer for agricultural production. After high-temperature activation, the iron oxide-containing solid carbon residue is soaked in ferric chloride solution and treated at high temperature to obtain iron oxide-loaded activated carbon. It has the following characteristics: (1) The raw materials are widely available, and the extraction of various beneficial components from biomass gasification residue and the application of biomass gasification residue with high added value can be achieved with relatively low cost and simple methods. At the same time, the purpose of treating waste with waste can be achieved, and the emission of greenhouse gases from thermal power plants can be reduced; (2) Biomass gasification residue is utilized in a comprehensive manner, which not only avoids the environmental pollution caused by the stockpiling of biomass residue, but also realizes the resource utilization of biomass residue. At the same time, it reduces the production cost of metal-loaded activated carbon, produces high-performance activated carbon, and has good economic, social and environmental benefits, promoting the industrialization and sustainable development of biomass energy; (3) It makes full use of various components in the raw materials and fully utilizes the chemical reagents used to achieve zero pollution; (4) It realizes the recycling of water and achieves zero emissions. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a flowchart of a method for the resource utilization of biomass gasification residue according to the present invention. Detailed Implementation

[0015] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the following description is provided in conjunction with the accompanying drawings. Figure 1 The present invention will be further described in detail below with reference to specific embodiments.

[0016] The technical solutions of the embodiments of the present invention will now be clearly and completely described with reference to the accompanying drawings.

[0017] In this embodiment, the biomass gasification residue is dried and ground into fine powder to expose the minerals containing silicon, aluminum, iron, and other elements trapped within the residue. Drying is performed using an oven (model KH-110C), and stirring is done using a magnetic stirrer (model HWCL-3). The biomass gasification residue is ground using a vertical planetary ball mill with a speed setting of 200-400 r / min. The mill rotates clockwise for 10-20 minutes, counter-clockwise for 10-20 minutes, with a rotation reversal interval of 0-2 minutes. The total milling time is 3-4 hours. Example 1

[0018] This embodiment provides a method for preparing supported iron oxide activated carbon for the reuse of biomass gasification residue, specifically including the following steps: 1) 100g of straw gasification residue was dried at 100℃ for 12h, then ground and sieved to expose the nitrogen, phosphorus, potassium, and other minerals trapped in the biomass gasification residue, yielding 500-mesh straw solid residue. The straw solid residue was added to 700mL of a 2.5mol / L sodium hydroxide solution and stirred with a magnetic stirrer at 80℃ and 400r / min for 2h. Solid-liquid separation was performed to separate residual carbon solid containing iron oxide and waste liquid containing silicon, calcium, phosphorus, etc. The residual carbon solid was placed in an oven and dried at 105℃ for 13h to obtain residual carbon solid material with a moisture content not exceeding 5%.

[0019] 2) Slowly pass carbon dioxide, a greenhouse gas emitted from a thermal power plant, into the waste liquid containing silicon, calcium, and phosphorus from step 1) until the pH reaches 9. At this point, the system is in a sol state. Then, slowly add a small amount of ammonium sulfate flocculant (the mass ratio of ammonium sulfate to waste liquid is 1:60) until a large amount of white flocculent precipitate suddenly forms. Filter and wash thoroughly until the filter cake is neutral to obtain a silicon-containing precipitate solid sample and a potassium, sodium, and phosphorus-containing waste liquid. The potassium, sodium, and phosphorus-containing waste liquid obtained after the reaction is dried and used to produce potassium-based compound fertilizer, such as potassium-phosphorus-sodium compound fertilizer, for agricultural production. The silicon-containing precipitate solid sample is used to produce sodium silicate and inorganic silicon chemical products, which can be used in building materials, detergent industries, and other fields.

[0020] 3) Wash the iron oxide-containing residual carbon solid from 1) until neutral, dry it, transfer it to a tube furnace, introduce nitrogen gas at a flow rate of 0.2 L / min as a protective gas, and introduce steam at a flow rate of 0.2 L / min as an activator, and activate it at 850℃ for 2 hours to obtain activated carbon.

[0021] Activated carbon was soaked in a 2.5 mol / L ferric chloride solution for 22 hours, then removed and dried in an oven at 120°C for 15 hours to obtain activated carbon loaded with ferric hydroxide, ferric chloride and a small amount of ferric oxide, which was then dried.

[0022] Activated carbon loaded with ferric hydroxide, ferric chloride and a small amount of ferric oxide was transferred to a tube furnace. Nitrogen gas with a flow rate of 0.3 L / min was introduced as a protective gas. Nitrogen gas was introduced throughout the entire process of heating, holding and cooling in the high-temperature treatment. After the tube furnace was filled with nitrogen, heating was started. The heating rate of the tube furnace was controlled at 20 °C / min. The temperature was heated to 450 °C and then held at 400 °C for 4 hours. The tube furnace was then closed and cooled to room temperature. The nitrogen valve was then closed.

[0023] Iron salts loaded on activated carbon are dried with water at 80-110℃ to form ferric hydroxide and a small amount of ferric oxide, which adhere to the activated carbon. The ferric hydroxide is then calcined at 450℃ to convert into ferric oxide. The final product has a specific surface area of ​​600 m². 2 / g, iodine adsorption value of supported iron oxide activated carbon is 1200mg / g. Example 2

[0024] This embodiment provides a method for preparing supported iron oxide activated carbon for the reuse of biomass gasification residue, specifically including the following steps: 1) Dry and grind 80g of wheat straw gasification residue into a fine powder to expose the potassium, calcium, phosphorus, and other minerals trapped in the biomass gasification residue, obtaining 450-mesh wheat straw solid residue; stir 500mL of 3.5mol / L sodium hydroxide solution at 90℃ for 3h. After the reaction, solid-liquid separation is performed to obtain waste liquid containing silicon, potassium, sodium, and phosphorus, and residual carbon solid containing iron oxide; place the residual carbon solid in an oven and dry it at 108℃ for 12h to obtain residual carbon solid material with a moisture content of no more than 5%.

[0025] 2) In step 1), carbon dioxide, a gas discharged from a thermal power plant, is slowly introduced into the waste liquid containing silicon, potassium, and calcium until the pH reaches 10. At this point, the system is in a sol state. Ammonium chloride is then slowly added as a flocculant at a flocculant-to-waste liquid mass ratio of 1:50. The mixture is continuously stirred until a large amount of white flocculent precipitate suddenly forms. The precipitate is filtered and thoroughly washed until the filter cake is neutral, yielding a silicon-containing solid sample and a potassium, sodium, and phosphorus-containing waste liquid. The silicon-containing solid sample is used to produce sodium silicate and inorganic silicon chemical products, such as silicon-based anodes. The potassium, sodium, and phosphorus-containing waste liquid is used to produce potassium-based compound fertilizers, such as potassium dihydrogen phosphate compound fertilizer, for use in the cultivation of various fruits and vegetables.

[0026] 3) The residual carbon solid containing iron oxide in 1) is fed into a tube furnace for high-temperature activation. During the activation process, nitrogen is used as an inert protective gas and water vapor is used as an activating agent. Water vapor is continuously introduced into the tube furnace at a flow rate of 0.4 L / min. The heating rate of the tube furnace is controlled at 16℃ / min, the activation temperature is 900℃, and nitrogen is introduced at a flow rate of 0.4 L / min as a protective gas during the activation process. The activation time is 3 hours.

[0027] 3) The residual carbon solid containing iron oxide from 1) is fed into a tube furnace for high-temperature activation. During the activation process, nitrogen is used as an inert protective gas and water vapor is used as an activating agent. Water vapor is continuously introduced into the tube furnace at a flow rate of 0.3 L / min. The heating rate of the tube furnace is controlled at 16℃ / min. The temperature is raised to 900℃ and the activation time is 1.5h to obtain activated carbon. Activated carbon was soaked in a 3 mol / L ferric chloride solution for 20 h, then removed and dried in an oven at 100 °C for 14 h to obtain metallic activated carbon. Nitrogen gas was used as an inert protective gas throughout the entire process of heating, holding, and cooling in the high-temperature treatment, with a nitrogen flow rate controlled at 0.3 L / min. The loaded metallic activated carbon was subjected to high-temperature treatment at 420 °C, with a controlled heating rate of 17 °C / min, and held at 380 °C for 3.5 h; after the reaction was completed, it was cooled to room temperature.

[0028] Iron salts loaded on activated carbon are dried with water at 100-120℃ to form ferric hydroxide and a small amount of ferric oxide, which adhere to the activated carbon. The ferric hydroxide is then calcined at 420℃ to convert into ferric oxide. The final product has a specific surface area of ​​450 m². 2 / g, with an iodine adsorption value of 1150mg / g, supported iron oxide activated carbon. Example 3

[0029] This embodiment provides a method for preparing supported iron oxide activated carbon for the reuse of biomass gasification residue, specifically including the following steps: 1) 70g of forest gasification residue was dried and ground into a fine powder to expose the minerals containing silicon, aluminum, iron, phosphorus, and other elements trapped in the biomass gasification residue, resulting in 420-mesh forest solid residue. 400mL of a 4.4mol / L sodium hydroxide solution was added to the forest solid residue, and the mixture was stirred at 100℃ for 4 hours. After the reaction, solid-liquid separation was performed to obtain a waste liquid containing phosphorus, sodium, and potassium, and residual carbon solids. The residual carbon solids were placed in an oven and dried at 110℃ for 14 hours to obtain residual carbon solid material with a moisture content not exceeding 5%.

[0030] 2) Slowly pass carbon dioxide, the exhaust gas from the thermal power plant, into the waste liquid containing phosphorus, sodium, and potassium in 1) until the pH reaches 11. At this point, the system is in a sol state. Then, slowly add ammonium phosphate flocculant, with a mass ratio of ammonium phosphate to waste liquid of 1:60. Stir continuously until a large amount of white flocculent precipitate is suddenly produced. Filter and wash thoroughly until the filter cake is neutral to obtain a silicon-containing precipitate solid sample and a sodium and phosphorus-containing waste liquid. The silicon-containing precipitate solid sample is used to make sodium silicate and inorganic silicon chemical products, such as silica sol, for use in the chemical industry. The sodium and phosphorus-containing waste liquid is used to make potassium-based compound fertilizer, such as potassium sulfate-type ternary compound fertilizer with a nitrogen-phosphorus-potassium ratio of 15:10:25.

[0031] 3) The residual carbon solid from 1) is fed into a tube furnace for high-temperature activation. During the activation process, nitrogen gas with a flow rate of 0.2 L / min is used as an inert protective gas, and water vapor as an activating agent is continuously introduced into the tube furnace at a flow rate of 0.5 L / min. The heating rate of the tube furnace is controlled at 17℃ / min, and the temperature is raised to 950℃. The activation time is 2.5 h. The activated carbon loaded with ferric hydroxide, ferric chloride and a small amount of ferric oxide is heated to 500℃ in the tube furnace and held for 4 h to obtain activated carbon. Activated carbon was soaked in a 3.5 mol / L ferric chloride solution for 24 hours, then removed and dried in an oven at 80°C for 13 hours to obtain metallic activated carbon. Nitrogen gas was used as an inert protective gas and was introduced throughout the entire process of heating, holding, and cooling in the high-temperature treatment. The loaded metallic activated carbon was subjected to high-temperature treatment. After the nitrogen gas was filled, heating was started, and the heating temperature was controlled at 550°C with a heating rate of 18°C / min. The holding temperature was controlled at 500°C for 4.5 hours. After the reaction was completed, the carbon was cooled to room temperature to obtain activated carbon loaded with metal oxides.

[0032] Iron salts loaded on activated carbon are dried with water at 70-100℃ to form ferric hydroxide and a small amount of ferric oxide, which adhere to the activated carbon. The ferric hydroxide is then calcined at 550℃ to convert into ferric oxide. The final product has a specific surface area of ​​500 m². 2 / g, with an iodine adsorption value of 1160mg / g, loaded with iron oxide activated carbon. Example 4

[0033] This embodiment provides a method for preparing supported iron oxide activated carbon for the reuse of biomass gasification residue, specifically including the following steps: 1) Dry and grind 200g of fruit shell gasification residue into fine powder to expose the potassium, calcium, phosphorus and other minerals trapped in the biomass gasification residue, and obtain 580 mesh biomass solid residue; add 1000mL of 3mol / L alkaline solution to the fruit shell solid residue, stir and react at 90℃ for 4h, and after the reaction, separate the solid and liquid to obtain waste liquid containing aluminum, sodium and calcium and residual carbon solid; place the residual carbon solid in an oven, control the temperature at 102℃, and dry for 15h to obtain residual carbon solid material with a moisture content of no more than 5%; 2) Slowly pass carbon dioxide, the exhaust gas from the thermal power plant, into the waste liquid containing aluminum, calcium, and sodium in 1) until the pH reaches 9. At this point, the system is in a sol state. Then slowly add ammonium chloride flocculant at a flocculant-to-waste liquid mass ratio of 1:70. Stir continuously until a large amount of white flocculent precipitate is suddenly produced. Filter and wash thoroughly until the filter cake is neutral to obtain a silicon-containing precipitate solid sample and a potassium, nitrogen, and phosphorus-containing waste liquid. The silicon-containing precipitate solid sample is used to make sodium silicate and inorganic silicon chemical products, such as water glass. The potassium, nitrogen, and phosphorus-containing waste liquid is used to make potassium-based compound fertilizer, such as potassium sulfate compound fertilizer.

[0034] 3) The residual carbon solid from 1) was fed into a tube furnace for high-temperature activation. During activation, nitrogen gas at a flow rate of 0.3 L / min was introduced as an inert protective gas, and water vapor at a flow rate of 0.3 L / min was introduced as an activating agent. The activation temperature was 945℃, and the activation time was 1.8 h. The heating rate of the tube furnace was controlled at 20℃ / min, and the temperature was held at 500℃ for 3.8 h to obtain activated carbon. Activated carbon was soaked in a 4 mol / L mixed solution of ferric chloride and potassium chloride (mass ratio 3:1) for 23 hours, then dried in an oven at 120°C for 10 hours to obtain metallic activated carbon. Nitrogen gas was used as an inert protective gas and was introduced throughout the entire high-temperature treatment process (heating, holding, and cooling) at a controlled flow rate of 0.3 L / min. The loaded metallic activated carbon was subjected to high-temperature treatment, heated to 500°C at a controlled rate of 18°C / min, and held at 480°C for 4.9 hours. After the reaction, it was cooled to room temperature. The iron salts loaded on the activated carbon formed ferric hydroxide and a small amount of ferric oxide under the action of water and hot drying at 80-100°C, adhering to the activated carbon. The ferric hydroxide was calcined at 500°C to convert into ferric oxide. The final product had a specific surface area of ​​380 m². 2 / g, iodine adsorption value of supported iron oxide activated carbon is 910mg / g. Example 5

[0035] This embodiment provides a method for preparing supported iron oxide activated carbon for the reuse of biomass gasification residue, specifically including the following steps: 1) 800g of biomass waste gasification residue was dried and ground into a fine powder to expose the nitrogen, phosphorus, potassium, and other elemental minerals trapped in the biomass gasification residue, resulting in 600-mesh biomass solid residue. 1500mL of a 4.8mol / L sodium hydroxide solution was added to the biomass waste gasification solid residue, and the mixture was stirred at 100℃ for 3 hours. After the reaction, solid-liquid separation was performed to obtain a waste liquid containing nitrogen, phosphorus, and potassium, and residual carbon solid containing iron oxide. The residual carbon solid was placed in an oven and dried at 110℃ for 13.5 hours to obtain residual carbon solid material with a moisture content not exceeding 5%. 2) In the waste liquid containing silicon, potassium, calcium, and sodium from step 1), carbon dioxide, a gas discharged from the thermal power plant, is slowly introduced until the pH reaches 9.8. At this point, the system is in a sol state. Then, ammonium phosphate flocculant is slowly added, with a mass ratio of ammonium phosphate to waste liquid of 1:80. The mixture is stirred continuously until a large amount of white flocculent precipitate is suddenly produced. The precipitate is filtered and thoroughly washed until the filter cake is neutral, yielding a silicon-containing precipitate solid sample and a nitrogen, phosphorus, and potassium-containing waste liquid. The silicon-containing precipitate solid sample is used to produce sodium silicate and inorganic silicon chemical products, such as sodium metasilicate, for use in the chemical industry. The nitrogen, phosphorus, and potassium-containing waste liquid is used to produce potassium-based compound fertilizers, for example, high-potassium compound fertilizers.

[0036] 3) The residual carbon solid from 1) is fed into a tube furnace for high-temperature activation. During the activation process, water vapor is introduced as an activating agent. The water vapor is continuously introduced into the tube furnace at a flow rate of 0.5 L / min. The heating rate of the tube furnace is controlled at 18℃ / min. The temperature is raised to 810℃ and the activation time is 3h to obtain activated carbon. Nitrogen gas at a flow rate of 0.3 L / min is introduced as a protective gas during the activation process.

[0037] Activated carbon was soaked in a 4.5 mol / L ferric sulfate solution for 21 h, then removed and dried in an oven at 110 °C for 12 h to obtain metallic activated carbon. Nitrogen was used as an inert protective gas, with a flow rate controlled at 0.3 L / min, to treat the loaded metallic activated carbon at a high temperature of 400 °C at a controlled heating rate of 16 °C / min, and held at 350 °C for 5 h. After the reaction was completed, the mixture was cooled to room temperature to obtain a specific surface area of ​​480 m². 2 / g, iodine adsorption value of supported iron oxide activated carbon is 980mg / g. Example 6

[0038] This embodiment provides a method for preparing supported iron oxide activated carbon for the reuse of biomass gasification residue, specifically including the following steps: 1) 800g of biomass gasification residue, a mixture of straw residue, rice husk residue, and timber, was dried at 100℃ for 12 hours. The residue was then ground and sieved to expose the nitrogen, phosphorus, potassium, and iron minerals trapped within, yielding 550-mesh straw solid residue. The straw solid residue was added to 700mL of a 2.2mol / L sodium hydroxide solution and stirred with a magnetic stirrer at 80℃ and 400r / min for 2 hours. Solid-liquid separation was performed to separate residual carbon solid containing iron oxide and waste liquid containing silicon, potassium, sodium, and phosphorus. The residual carbon solid was placed in a 109℃ oven and dried for 12.5 hours to obtain residual carbon solid material with a moisture content not exceeding 5%.

[0039] 2) Slowly pass carbon dioxide, a greenhouse gas emitted from a thermal power plant, into the waste liquid containing silicon, potassium, and sodium from step 1) until the pH reaches 10. At this point, the system is in a sol state. Then, slowly add a small amount of ammonium sulfate flocculant (ammonium sulfate to waste liquid mass ratio 1:90) until a large amount of white flocculent precipitate suddenly forms. Filter and wash thoroughly until the filter cake is neutral to obtain a silicon-containing precipitate solid sample and a sodium and phosphorus-containing waste liquid. The sodium and phosphorus-containing waste liquid obtained after the reaction is dried and used to produce potassium-based compound fertilizer (such as potassium-phosphorus-calcium-magnesium compound fertilizer) for agricultural production. The silicon-containing precipitate solid sample is used to produce sodium silicate and inorganic silicon chemical products, which can be used in building materials, detergent industries, and other fields.

[0040] 3) Wash the iron oxide-containing residual carbon solid from 1) until neutral, dry it, transfer it to a tube furnace, introduce nitrogen gas at a flow rate of 0.2 L / min as a protective gas, and introduce steam at a flow rate of 0.6 L / min as an activator, and activate it at 880℃ for 2 h to obtain activated carbon.

[0041] Activated carbon was soaked in a 5 mol / L ferric sulfate solution for 20 h, then removed and dried in an oven at 120 °C for 11 h to obtain activated carbon loaded with ferric hydroxide, ferric chloride and a small amount of ferric oxide, and then dried.

[0042] Activated carbon loaded with ferric hydroxide, ferric chloride, and a small amount of ferric oxide was transferred to a tube furnace. Nitrogen gas with a flow rate of 0.3 L / min was introduced as a protective gas. Nitrogen gas was introduced throughout the entire process of heating, holding, and cooling in the high-temperature treatment. After the tube furnace was filled with nitrogen, heating was started. The heating rate of the tube furnace was controlled at 15 °C / min, and the heating temperature was controlled to 460 °C. The temperature was held at 400 °C for 3 hours. Then the tube furnace was turned off, cooled to room temperature, and the nitrogen valve was closed.

[0043] Iron salts loaded on activated carbon are dried with water at 100-130℃ to form ferric hydroxide and a small amount of ferric oxide, which adhere to the activated carbon. The ferric hydroxide is then calcined at 460℃ to convert into ferric oxide. The final product has a specific surface area of ​​560 m². 2 / Supported iron oxide activated carbon with an iodine adsorption value of 1180 mg / g.

[0044] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing supported iron oxide activated carbon for the reuse of biomass gasification residue, characterized in that, Includes the following steps: Step 1: Dry and grind the biomass gasification residue into fine powder to obtain 400-600 mesh biomass solid residue; add 2-5 mol / L alkaline solution to the biomass solid residue, stir and mix, and heat. After reaction, separate the solid and liquid to obtain waste liquid containing silicon, aluminum, sodium, calcium, and phosphorus, and residual carbon solid containing iron oxide; place the residual carbon solid in an oven, control the temperature at 100℃-110℃, and dry for 12-15 hours to obtain residual carbon solid material with a moisture content of no more than 5%; Step 2: Slowly pass carbon dioxide, a greenhouse gas emitted from a thermal power plant, into the waste liquid containing silicon, aluminum, calcium, and sodium from Step 1 until the pH reaches 9-11. At this point, the system is in a sol state. Then, slowly add flocculant at a mass ratio of 1:40 to 1:100 to the waste liquid. Stir continuously until a large amount of white flocculent precipitate is suddenly produced. Filter and wash thoroughly until the filter cake is neutral to obtain a solid sample containing silicon precipitate and waste liquid containing aluminum, sodium, and phosphorus. The silicon-containing precipitate solid samples are used to produce sodium silicate and inorganic silicon chemical products; the waste liquid containing aluminum, sodium and phosphorus is used to produce potassium-based compound fertilizer. Step 3: The residual carbon solid containing iron oxide from Step 1 is fed into a tube furnace for high-temperature activation. During the activation process, nitrogen is used as an inert protective gas and water vapor is used as an activating agent. Water vapor is continuously introduced into the tube furnace at a flow rate of 0.2-0.66 L / min. The heating rate of the tube furnace is controlled at 15-22℃ / min, and the temperature is raised to 800-950℃. The activation time is 1-3 hours to obtain activated carbon. The activated carbon was then soaked in a 2-5 mol / L metal salt solution for 20-24 hours, removed, and dried at 80-120℃ for 10-15 hours to obtain metal activated carbon. Nitrogen was used as an inert protective gas to treat the loaded metal activated carbon at high temperature. After the nitrogen was filled, heating was started, and the heating temperature was controlled at 350-550℃ with a heating rate of 15-22℃ / min. The holding temperature was controlled at 400-500℃ for 3-5 hours. After the reaction was completed, the carbon was cooled to room temperature to obtain activated carbon loaded with metal oxide.

2. The method for preparing supported iron oxide activated carbon for the reuse of biomass gasification residue as described in claim 1, characterized in that: In step one, the biomass gasification slag grinding equipment adopts a vertical planetary ball mill with a rotation speed of 200-400 r / min, clockwise rotation for 10-20 min, counterclockwise rotation for 10-20 min, rotation reversal interval of 0-2 min, and a total ball milling time of 3-4 h.

3. The method for preparing supported iron oxide activated carbon for the reuse of biomass gasification residue as described in claim 1, characterized in that: The alkaline solution is selected from one or a combination of potassium hydroxide and sodium hydroxide solutions, and the reaction time is optimal to ensure sufficient reaction with silicon, aluminum, calcium and sodium elements in the biomass ash.

4. The method for preparing supported iron oxide activated carbon for the reuse of biomass gasification residue as described in claim 1, characterized in that: The biomass gasification residue mentioned in step one is one or a mixture of two or more of the following: straw residue, wheat straw residue, forest wood residue, fruit shell residue, and vegetable waste pyrolysis residue.

5. The method for preparing supported iron oxide activated carbon for the reuse of biomass gasification residue as described in claim 1, characterized in that: In step two, the flocculant is one of the inorganic ammonium salts of ammonium sulfate, ammonium chloride, and ammonium phosphate.

6. The method for preparing supported iron oxide activated carbon for the reuse of biomass gasification residue as described in claim 1, characterized in that: The nitrogen protective gas is introduced throughout the entire process of heating, heat preservation, and cooling in the high-temperature treatment.

7. The method for preparing supported iron oxide activated carbon for the reuse of biomass gasification residue as described in claim 1, characterized in that: In step three, the metal salt solution is selected from either ferric chloride or ferric sulfate solution.

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