Preparation process of activated carbon capable of being automatically regenerated for oil-gas separation

Abstract

The invention relates to the technical field of activated carbon preparation, and discloses a preparation process of activated carbon capable of being automatically regenerated for oil-gas separation, and the activated carbon comprises the following components by mass: 80-120 parts of biochar; 20 parts by mass to 40 parts by mass of a binder; the preparation process comprises the following steps: crushing a biomass raw material to 180-325 meshes, and conveying the crushed biomass raw material to a material powder storage tank through a fan for later use; mixing and kneading the material powder and a binder, extruding and granulating, drying, carbonizing and activating; pretreating activated carbon, soaking with monopotassium phosphate, performing microwave radiation activation, and performing suction filtration and drying; and performing acid cleaning, water washing, dehydration and drying on the modified activated carbon to obtain a finished product.

Description

Technical Field

[0001] The present invention relates to the technical field of activated carbon preparation, in particular to a process for preparing automatically regenerated activated carbon for oil and gas separation. Background Art

[0002] Oil and gas separation is a key component of industrial production and environmental protection, particularly in the recovery and treatment of volatile organic compounds (VOCs) generated in petrochemicals, coatings, fuel storage, and transportation. With the acceleration of industrialization, oil and gas pollution is becoming increasingly prominent, posing a potential threat to the atmospheric environment and human health.

[0003] Due to its unique physical and chemical properties, such as high specific surface area, rich pore structure, and diverse surface functional groups, activated carbon is widely used in a variety of fields, including gas adsorption and liquid purification, including oil and gas separation by adsorption. In oil and gas separation applications, activated carbon is typically used as an adsorbent, selectively removing oil and gas components from a mixed gas stream through physical or chemical adsorption for purification or recovery. Its granular or molded structure allows for easy loading into adsorption towers or beds for continuous or intermittent operation.

[0004] However, after existing activated carbon reaches adsorption saturation, its regeneration process consumes high energy and has poor regeneration efficiency, making it difficult to restore its initial adsorption performance. After multiple adsorption-regeneration cycles, the adsorption capacity significantly decreases, shortening the material's service life. During actual operation, activated carbon particles are easily broken and pulverized due to mechanical stress (such as loading, transportation, airflow impact, or friction). This not only leads to material loss and increased operating costs, but can also cause equipment clogging. Therefore, the present invention provides a process for preparing automatically regenerable activated carbon for oil and gas separation to address the shortcomings of the existing technology. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention provides a process for preparing automatically regenerable activated carbon for oil and gas separation, which solves the problems in the existing technology of insufficient adsorption capacity, regeneration efficiency and mechanical strength of activated carbon, resulting in low oil and gas separation efficiency, short service life and high operation and maintenance costs.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: A first aspect of the present invention provides a self-regenerating activated carbon for oil and gas separation, comprising the following components in parts by mass: 100 parts by mass of biochar; 20 parts by mass to 40 parts by mass of a binder; and 1 part by mass to 5 parts by mass of potassium dihydrogen phosphate.

[0007] The biochar is formed by carbonizing and activating biomass raw materials rich in cellulose, hemicellulose, and lignin. The biochar serves as the main skeleton of the adsorbent, providing the basic pore structure and specific surface area.

[0008] The potassium dihydrogen phosphate is used as a modifier for impregnating modified activated carbon. During the preparation and modification of activated carbon, potassium dihydrogen phosphate can promote the formation and regulation of pore structure, increase the number of oxygen-containing functional groups on the surface of the activated carbon, and thus enhance the activated carbon's adsorption capacity for oil and gas molecules.

[0009] The binder is used to bind the biochar particles into shape to ensure the mechanical strength and stability of the activated carbon product. The binder is selected from starch, polyvinyl alcohol or coal tar pitch. The starch includes amylose and amylopectin, and the mass ratio of the amylose to the amylopectin is in the range of 3:17-7:13. The degree of alcoholysis of the polyvinyl alcohol is 85.0%-99.5%, and the degree of polymerization is 500-2500. The softening point of the coal tar pitch is 70℃-150℃, and the coking value is 45%-65%. These binders can be converted into carbon during the carbonization process, further consolidating the structure of the activated carbon and participating in the formation of pores.

[0010] A second aspect of the present invention provides a process for preparing automatically regenerable activated carbon for oil and gas separation. The process is applied to prepare the aforementioned automatically regenerable activated carbon for oil and gas separation, and comprises the following steps: S1. Crushing and preparation of biomass raw materials: The biomass feedstock is conveyed into a grinder for mechanical pulverization. During the pulverization process, the particle size of the feed is controlled, with a target range of 180 to 325 mesh, and a minimum of 95% passing through the target size sieve. The pulverized feed is then conveyed by a fan to a sealed storage tank for future use.

[0011] S2. Preparation of activated carbon: The obtained powder and binder are added to a kneader in a mass ratio of 3:1 and mixed and kneaded to obtain a plastic paste. This kneading process ensures the uniform mixing of the powder and binder, laying the foundation for subsequent molding.

[0012] The paste is fed into a granulation molding machine, and is extruded and granulated through a die of specific specifications under high pressure to form an activated carbon particle precursor.

[0013] The activated carbon granules are dried to reduce their moisture content to below 5%. This drying step removes moisture from the granules, creating conditions for subsequent high-temperature carbonization and activation, and preventing water vapor interference. Drying can be done using a combination of cold air and natural air drying.

[0014] The dried activated carbon particles are fed into an externally heated, sealed, oxygen-free, high-efficiency, energy-saving carbonization furnace equipped with a rotating drum. Carbonization takes place at low temperatures of 300-550°C. This process, carried out in an oxygen-free environment, promotes the pyrolysis and removal of non-carbon components in the biomass, initially forming a carbon skeleton and pore structure.

[0015] After low-temperature carbonization, the material is sent to an activation furnace for high-temperature activation at 800-900°C to form activated carbon. The activation process uses high-temperature gas activation (such as water vapor, carbon dioxide, or a mixture of the two) to further etch the carbon skeleton, expand the pore volume and specific surface area, and form a well-developed porous structure.

[0016] S3. Modification of activated carbon: The activated carbon is pretreated, which includes repeatedly washing the activated carbon with deionized water until the pH value of the washing solution is consistent with that of the deionized water, and then drying the activated carbon at a temperature of 100° C. to 120° C. for 12 to 36 hours.

[0017] The pretreated activated carbon is immersed in a 5%-15% potassium dihydrogen phosphate solution at 50°C-70°C for 12-36 hours. This immersion process allows the potassium dihydrogen phosphate to fully penetrate the pore structure of the activated carbon. As a modifier, potassium dihydrogen phosphate can further optimize the activated carbon's pore size and improve its surface chemistry during subsequent microwave radiation activation, such as increasing oxygen-containing functional groups, thereby enhancing its adsorption performance.

[0018] The soaked activated carbon is then activated by microwave radiation. The microwave radiation activation conditions are: irradiation at a microwave power of 400W-700W for 30-60 minutes. Microwave radiation provides energy, allowing potassium dihydrogen phosphate to act within the activated carbon, further activating and modifying the activated carbon structure, promoting the formation of micropores and mesopores, and potentially forming specific active sites on its surface.

[0019] After microwave activation, excess potassium dihydrogen phosphate solution is removed by filtration. The purpose of filtration is to separate the activated carbon from the excess impregnation solution.

[0020] The activated carbon after filtration was dried at 110°C to constant weight to obtain modified activated carbon. This drying step is intended to remove moisture and stabilize the structure and properties of the activated carbon.

[0021] S4. Cleaning and drying of adsorbent: The modified activated carbon is sent to the cleaning device, injected with water and hydrochloric acid, and stirred with high-pressure gas to form an acidic cleaning solution with a concentration of 3%-8% by mass, and soaked for 10 minutes.

[0022] The cleaning solution is heated to 90-100°C and maintained at this temperature for 20-60 minutes. The high temperature and continuous stirring promote the dissolution and separation of impurities.

[0023] High-pressure gas and steam are alternately introduced into the cleaning device for 1-2 hours, and the cleaning liquid temperature is maintained at 60° C. to 80° C. This alternating flushing further enhances the cleaning effect and ensures the thorough removal of impurities.

[0024] After cleaning, the cleaning solution is discharged and the activated carbon is washed with water until the pH value of the cleaning solution is close to neutral. The purpose of water washing is to completely remove the residual acidic cleaning solution and ensure the purity of the product.

[0025] The washed activated carbon is vacuum filtered and dehydrated. This dehydration step is intended to remove as much water as possible from the activated carbon particles in preparation for final drying.

[0026] The dehydrated activated carbon is then fed to a vibrating fluidized bed for hot air drying and screening, resulting in the final, self-regenerating activated carbon product for oil and gas separation. The vibrating fluidized bed drying method enables uniform and efficient drying of the activated carbon, while also performing screening to ensure uniform product particle size and moisture content.

[0027] The present invention provides a process for preparing automatically regenerable activated carbon for oil and gas separation. It has the following beneficial effects: 1. This invention introduces potassium dihydrogen phosphate as a modifier during the preparation process and activates the activated carbon through microwave radiation under specific conditions, optimizing its internal pore structure and developing surface chemical properties that are conducive to adsorption. This modified activated carbon exhibits a higher adsorption affinity for oil and gas components, significantly increasing its penetration and saturation adsorption capacities, enabling more efficient removal of pollutants from oil and gas, and improving purification efficiency.

[0028] 2. This invention involves mixing and kneading biomass raw materials with a binder, followed by granulation, drying, carbonization, and activation. The binder is converted to carbon during the high-temperature carbonization process, forming a denser structure with the biochar skeleton, significantly enhancing the mechanical strength and physical stability of the final activated carbon product. This helps the activated carbon resist external impact and abrasion in oil and gas separation applications.

[0029] 3. The introduction of potassium dihydrogen phosphate in this invention helps stabilize the activated carbon's skeleton structure, reducing irreversible adsorption of adsorbates during the desorption process. Combined with microwave radiation activation, it promotes uniform distribution of potassium dihydrogen phosphate, further enhancing the activated carbon's structural integrity during multiple adsorption-desorption cycles. This allows the activated carbon to effectively restore its adsorption capacity after regeneration, extending its service life and reducing operating costs and waste disposal. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a flow chart of the preparation process of the present invention. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the present specification. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] The sources and specifications of the main raw materials and reagents used in the following examples and comparative examples are as follows. Reagents not specifically specified are all commercially available products of analytical grade or higher.

[0033] Binder: Corn starch: food grade, CAS number: 9005-25-8.

[0034] Polyvinyl alcohol: alcoholysis degree 88.0%±1.0%, polymerization degree 1700±100, CAS number: 9002-89-5.

[0035] Coal tar pitch: softening point 90℃, coking value 55%, CAS number: 8052-42-4.

[0036] Potassium dihydrogen phosphate: purity ≥99.0%, CAS number: 7778-77-0.

[0037] See attached Figure 1 , Example 1: Raw material components (by mass): 90 parts by mass of biochar; 27 parts by mass of binder; 3 parts by mass of potassium dihydrogen phosphate.

[0038] Preparation steps: Preparation of activated carbon: Biomass raw material crushing and storage: Corn stalks are conveyed into a grinder for mechanical crushing. The particle size of the powder is controlled, with a target particle size of 200 mesh, and the proportion of the powder passing through the target particle size screen is no less than 98%. The crushed powder is conveyed by a fan to a sealed powder storage tank for storage.

[0039] Mixing and kneading of the powder and the binder: Add the corn straw powder prepared above and polyvinyl alcohol at a mass ratio of 3:1 into a kneader at the same time, and knead for 30 minutes to obtain a plastic paste.

[0040] Extrusion granulation of paste: The mixed paste is fed into a granulation molding machine and extruded and granulated using a die with a pore size of 3 mm to form strip-shaped activated carbon particle precursors.

[0041] Drying of activated carbon granules: The granulated activated carbon granules are naturally dried at room temperature for 24 hours, and then dried with cold air at 40°C for 4 hours to reduce the moisture content of the activated carbon granules to 3%.

[0042] Carbonization of activated carbon particles: The dried activated carbon particles are fed into an externally heated, closed, oxygen-free, high-efficiency, energy-saving carbonization furnace with a rotary lifting drum device and carbonized at 400°C for 90 minutes.

[0043] Activation of activated carbon particles: After the low-temperature carbonization is completed, the material is sent to the activation furnace and activated at 850°C with water vapor as the activator for 60 minutes to form activated carbon.

[0044] Modification of activated carbon: Pretreatment of activated carbon: The activated carbon was washed with deionized water three times, each time for 20 minutes, until the pH value of the washing solution was consistent with that of deionized water. The washed activated carbon was then dried in an oven at 105°C for 24 hours.

[0045] Soaking in potassium dihydrogen phosphate solution: Place the pretreated activated carbon in a 10% potassium dihydrogen phosphate solution at 60°C for 24 hours. Stir the activated carbon during the soaking process to ensure that the potassium dihydrogen phosphate is fully penetrated.

[0046] Microwave radiation activation: The activated carbon after soaking was activated by microwave radiation at a microwave power of 539 W for 43 minutes.

[0047] Filtration and Drying: After microwave activation, vacuum filter the mixture through a Buchner funnel to remove excess potassium dihydrogen phosphate solution. The filtered activated carbon is then dried in an oven at 110°C to a constant weight (the difference between two consecutive weighings should be less than 0.01 g). This yields the modified activated carbon.

[0048] Cleaning and drying of adsorbent: Preparation and soaking of the acidic cleaning solution: The modified activated carbon is fed into a cleaning device. Hydrochloric acid and deionized water are mixed and stirred to prepare a 5% by mass acidic cleaning solution. High-pressure gas is introduced and stirred for 10 minutes. The activated carbon is then soaked in the cleaning solution for 10 minutes.

[0049] Heating and maintaining the temperature of the cleaning liquid: Steam is then introduced into the cleaning device to raise the temperature of the cleaning liquid to 95°C and maintain it for 30 minutes.

[0050] Alternating injection of high-pressure gas and steam: Alternately introduce high-pressure gas and steam into the cleaning device for 1.5 hours, and maintain the cleaning liquid temperature at 70°C.

[0051] Discharge of washing liquid and water washing of activated carbon: After the washing is completed, the washing liquid is discharged. After the washing liquid is discharged, deionized water is introduced to water wash the activated carbon material until the pH value of the washing liquid reaches 6.5-7.5.

[0052] Vacuum filtration dehydration: The water-washed activated carbon material is sent to a dehydrator for vacuum filtration dehydration for 15 minutes.

[0053] Vibration fluidized bed drying and screening: The dehydrated activated carbon material is sent to a vibration fluidized bed for hot air drying (drying temperature: 120°C) and screening (screening particle size: 2mm) to obtain the final oil-gas separation automatically regenerable activated carbon product.

[0054] Example 2: Raw material components (by mass fraction): Biochar 110 parts by mass; Binder 27.5 parts by mass; Potassium dihydrogen phosphate 4 parts by mass.

[0055] Preparation steps: Preparation of activated carbon: Pulverization and preparation of biomass raw material: The rice husk is transported into a pulverizer for mechanical pulverization, the particle size of the material powder is controlled, the target particle size is 250 mesh, and the proportion of the material powder passing through the target mesh screen is not less than 95%. The pulverized material powder is transported by a fan to a material powder storage tank for sealing and preparation.

[0056] Mixing and kneading of material powder and binder: The above prepared rice husk material powder and corn starch are simultaneously added into a mixing and kneading machine at a mass ratio of 4:1, and mixed and kneaded for 25 minutes to obtain a plastic paste.

[0057] Extrusion granulation of the paste: The mixed and kneaded paste is sent into a granulation forming machine, and extrusion granulation is performed using a mold with a pore diameter of 2mm to form granular activated carbon particle precursors.

[0058] Drying of activated carbon particles: The granulated activated carbon particles are naturally aired for 20 hours at room temperature, and then dried at 45°C for 3 hours using cold air to reduce the moisture content of the activated carbon particles to 4%.

[0059] Carbonization of activated carbon particles: The dried activated carbon particles are sent into an external heating type closed anaerobic high-efficiency energy-saving carbonization furnace of a rotatable material lifting cylinder device, and carbonized at 450°C for 100 minutes.

[0060] Activation of activated carbon particles: After the low-temperature carbonization is completed, the material is sent into an activation furnace, activated at 880°C using carbon dioxide as the activation agent (carbon dioxide flow rate: 0.6L / min) for 55 minutes to form activated carbon.

[0061] Modification of activated carbon: Pre-treatment of activated carbon: The formed activated carbon was washed repeatedly with deionized water for 2 times, each time for 15 minutes, until the pH value of the washing liquid was consistent with that of deionized water. Then the washed activated carbon was dried in an oven at 110°C for 18 hours.

[0062] Soaking in potassium dihydrogen phosphate solution: The pre-treated activated carbon was put into a potassium dihydrogen phosphate solution with a mass fraction of 12%, and soaked at a temperature of 65°C for 20 hours. Stirring was maintained during the soaking process.

[0063] Microwave radiation activation: The soaked activated carbon was subjected to microwave radiation activation, with a microwave power of 600W, for 35 minutes.

[0064] Vacuum filtration and drying: After the microwave activation was completed, the excess potassium dihydrogen phosphate solution was removed by vacuum filtration through a Buchner funnel. The filtered activated carbon was dried in an oven at 110°C until a constant weight was achieved.

[0065] Washing and drying of the adsorbent: Preparation and soaking of the acidic washing liquid: The modified activated carbon was sent to a washing device, and hydrochloric acid and deionized water were mixed to prepare an acidic washing liquid with a mass fraction of 6%. High-pressure gas was introduced for stirring for 8 minutes, and the activated carbon was soaked in the washing liquid for 12 minutes.

[0066] Warming and maintaining of the washing liquid: Then steam was introduced into the washing device to warm the washing liquid to 90°C and maintain for 40 minutes.

[0067] Alternating introduction of high-pressure gas and steam: High-pressure gas and steam were alternately introduced into the washing device for 1 hour and 45 minutes, with the temperature of the washing liquid maintained at 65°C.

[0068] Discharge of the washing liquid and water washing of the activated carbon: After the washing was completed, the washing liquid was discharged. After the discharge of the washing liquid was completed, deionized water was introduced to water wash the activated carbon material until the pH value of the washing liquid reached 6.5-7.5.

[0069] Vacuum filtration and dehydration: The water-washed activated carbon material was sent to a dehydrator for vacuum filtration and dehydration for 12 minutes.

[0070] Vibrating fluidized bed drying and screening: The dehydrated activated carbon material was sent to a vibrating fluidized bed for hot air drying (drying temperature: 115°C) and screening (screening particle size: 1.5mm) to obtain the final self-regenerable activated carbon product for oil-gas separation.

[0071] Example 3: Raw material components (by mass fraction): Biochar 105 mass parts; Binder 32 mass parts; Potassium dihydrogen phosphate 3.5 parts by mass.

[0072] Preparation step: Preparation of activated carbon: Crushing and preparation of biomass raw material: The sawdust is transported into a crusher for mechanical crushing, and the particle size of the material powder is controlled. The target particle size is 300 mesh, and the proportion of the material powder passing through the target mesh is not less than 97%. The crushed material powder is transported by a fan to a material powder storage tank for sealing and standby use.

[0073] Mixing and kneading of material powder and binder: The sawdust material powder prepared above and coal tar pitch are simultaneously added into a mixing and kneading machine at a mass ratio of 3:1, and mixed and kneaded for 35 minutes to obtain a plastic paste.

[0074] Extrusion granulation of the paste: The mixed and kneaded paste is sent into a granulation forming machine, and extrusion granulation is performed using a mold with a pore diameter of 2.5 mm to form cylindrical activated carbon particle precursors.

[0075] Drying of activated carbon particles: The granulated activated carbon particles are naturally aired for 28 hours at room temperature, and then dried at 35°C for 5 hours using cold air to reduce the moisture content of the activated carbon particles to 2%.

[0076] Carbonization of activated carbon particles: The dried activated carbon particles are sent into an outer-heating type closed anaerobic high-efficiency energy-saving carbonization furnace of a rotary material lifting drum device, and carbonized at 500°C for 100 minutes.

[0077] Activation of activated carbon particles: After low-temperature carbonization, the material is sent into an activation furnace, and activated at 800°C for 50 minutes using a mixed gas of water vapor and carbon dioxide as an activation agent to form activated carbon.

[0078] Modification of activated carbon: Pretreatment of activated carbon: The formed activated carbon is repeatedly washed with deionized water for 2 times, each time for 25 minutes, until the pH value of the washing liquid is consistent with that of deionized water. Then, the washed activated carbon is dried in an oven at 115°C for 30 hours.

[0079] Soaking in potassium dihydrogen phosphate solution: The pretreated activated carbon is placed into a potassium dihydrogen phosphate solution with a mass fraction of 8%, and soaked at a temperature of 55°C for 30 hours. Stirring is maintained during the soaking process.

[0080] Microwave radiation activation: The soaked activated carbon is subjected to microwave radiation activation at a microwave power of 650W for 40 minutes.

[0081] Suction filtration and drying: After microwave activation, the excess potassium dihydrogen phosphate solution is removed by vacuum suction filtration through a Buchner funnel. The suction-filtered activated carbon is dried in an oven at 110°C to a constant weight.

[0082] Cleaning and drying of the adsorbent: Preparation and soaking of the acidic cleaning solution: The modified activated carbon was sent to the cleaning device, hydrochloric acid and deionized water were mixed to prepare an acidic cleaning solution with a mass fraction of 4%. High-pressure gas was introduced for stirring for 12 minutes, and the activated carbon was soaked in the cleaning solution for 15 minutes.

[0083] Heating and maintaining of the cleaning solution: Steam was then introduced into the cleaning device to heat the cleaning solution to 90°C and maintain for 50 minutes.

[0084] Alternating introduction of high-pressure gas and steam: High-pressure gas and steam were alternately introduced into the cleaning device for 1 hour and 30 minutes, and the temperature of the cleaning solution was maintained at 75°C.

[0085] Discharge of the cleaning solution and water washing of the activated carbon: After the cleaning was completed, the cleaning solution was discharged. After the cleaning solution was discharged, deionized water was introduced to wash the activated carbon material until the pH value of the washing solution reached 6.5-7.5.

[0086] Vacuum filtration and dehydration: The water-washed activated carbon material was sent to the dehydrator for vacuum filtration and dehydration for 18 minutes.

[0087] Vibration fluidized bed drying and screening: The dehydrated activated carbon material was sent to the vibration fluidized bed for hot air drying (drying temperature 125°C) and screening (screening particle size 1.8 mm) to obtain the final self-regenerable activated carbon product for oil and gas separation.

[0088] Comparative Example 1: Compared with Example 1, the difference is that the soaking step of potassium dihydrogen phosphate solution is omitted, and the rest is the same.

[0089] Comparative Example 2: Compared with Example 2, the difference is that the microwave radiation activation step is omitted, and the rest is the same.

[0090] Comparative Example 3: Compared with Example 1, the difference is that the binder polyvinyl alcohol is replaced by traditional coal tar pitch, and the rest is the same.

[0091] Comparative Example 4: Compared with Example 3, the difference is that the acidic cleaning step is omitted, and only deionized water washing is performed, and the rest is the same.

[0092] Comparative Example 5: Compared with Example 1, the difference is that the mass fraction of potassium dihydrogen phosphate is 0.5 parts by mass. The rest is the same.

[0093] Experiment 1: Experimental purpose: To evaluate the adsorption capacity of each sample of activated carbon on oil and gas components (such as n-hexane).

[0094] Experimental steps: The dynamic adsorption method was used. The prepared activated carbon sample (2.00 g) was loaded into a fixed bed adsorption column (inner diameter 10 mm, length 200 mm). The adsorption column was placed in a thermostat and the adsorption temperature was maintained at 25°C. The prepared n-hexane-containing gas was passed into the adsorption column at a flow rate of 100 mL / min. The concentration of n-hexane at the outlet of the adsorption column was monitored in real time by a gas chromatograph (equipped with an FID detector). When the outlet n-hexane concentration reached 5% of the inlet concentration, it was recorded as the breakthrough point. When the outlet concentration reached 95% of the inlet concentration, it was recorded as the saturation point. The breakthrough adsorption capacity and saturation adsorption capacity of the activated carbon were calculated based on the gas flow rate, adsorption time and inlet concentration.

[0095] The experimental results are shown in Table 1.

[0096] Table 1: Oxygen index and thermal gravimetric loss test data

[0097] According to the experimental results shown in Table 1, the activated carbon prepared by the present invention exhibits significant advantages in adsorption performance. The activated carbon samples prepared in Examples 1, 2, and 3 have significantly higher breakthrough adsorption capacity and saturation adsorption capacity than the samples in Comparative Examples 1, 2, 3, 4, and 5.

[0098] Comparative Example 1, which did not undergo immersion in a potassium dihydrogen phosphate solution, exhibited significantly lower adsorption performance than the sample in the examples, demonstrating that the introduction of potassium dihydrogen phosphate plays a key role in improving the adsorption capacity of activated carbon. During the activation process, potassium dihydrogen phosphate forms a phosphorus oxide structure with the carbon skeleton, altering the surface chemistry and pore structure of the activated carbon, thereby enhancing its adsorption affinity for oil and gas components. Comparative Example 2, which omitted the microwave radiation activation step, also exhibited relatively low adsorption performance. This suggests that microwave radiation activation promotes the uniform distribution and effective fixation of potassium dihydrogen phosphate within the activated carbon pores, further optimizing the activated carbon's pore structure and thus improving adsorption efficiency.

[0099] Comparative Example 3 uses traditional coal tar pitch as a binder, and the ratio of powder to binder is different, and its adsorption performance is lower than that of the example sample. This shows that the type of binder selected by the present technical solution and its specific ratio to the biomass raw material have an optimizing effect on the formation of activated carbon pore structure and adsorption sites. The selection and ratio of the binder directly affect the structural evolution of the carbon precursor during carbonization and activation, and thus affect the adsorption performance of the final activated carbon. Comparative Example 4 is not acid-washed, and its adsorption performance is also lower than that of the example sample. The acid washing step can effectively remove the inorganic ash and impurities remaining on the surface and pores of the activated carbon, preventing them from clogging the pores or occupying adsorption sites, thereby exposing more effective adsorption surface area and improving adsorption efficiency. The amount of potassium dihydrogen phosphate used in Comparative Example 5 is lower than the range specified by the present technical solution, and its adsorption performance is significantly lower than that of the example sample. This shows that the mass fraction of potassium dihydrogen phosphate is within a specific range to fully exert its optimizing effect on the pore structure and surface chemical properties of activated carbon, thereby effectively improving the adsorption capacity. An appropriate amount of potassium dihydrogen phosphate helps to form a more developed pore structure and richer surface functional groups, thereby improving the adsorption efficiency of oil and gas components.

[0100] Experiment 2: Experimental purpose: To evaluate the regeneration efficiency of each sample of activated carbon and its performance stability after multiple adsorption-regeneration cycles.

[0101] Experimental steps: Adsorption saturation: Take out the activated carbon sample that has reached the saturated state in the adsorption performance test.

[0102] Regeneration by heating and desorption: The saturated activated carbon sample was transferred to a regeneration furnace. The sample was heated using a programmed temperature ramp from room temperature to 200°C at a rate of 5°C / min. Desorption was then maintained at 200°C for 30 minutes while pure nitrogen (100 mL / min) was introduced as a purge gas to remove n-hexane adsorbed on the activated carbon. The temperature was then raised to 350°C and desorption was continued at this temperature for 30 minutes.

[0103] Regeneration efficiency calculation: After regeneration is complete, cool the activated carbon to room temperature. Re-test the adsorption performance and record the saturated adsorption capacity after regeneration.

[0104] Cyclic test: Repeat the above-mentioned adsorption saturation and heating desorption regeneration steps for a total of 5 adsorption-regeneration cycles, and record the saturated adsorption capacity and regeneration efficiency after each regeneration.

[0105] The experimental results are shown in Table 2.

[0106] Table 2: Activated carbon regeneration performance test results

[0107] According to the regeneration performance test results shown in Table 2, the activated carbon prepared by this technical solution exhibits excellent regeneration performance and cyclic stability. The activated carbon samples of Examples 1, 2, and 3 maintained a high regeneration efficiency after multiple adsorption-regeneration cycles, and their adsorption capacity decay was much smaller than that of the comparative example.

[0108] Comparative Example 1 was not soaked in potassium dihydrogen phosphate solution, and its regeneration efficiency was significantly lower than that of the example sample, and its cyclic stability was poor. This shows that the introduction of potassium dihydrogen phosphate not only enhances adsorption capacity, but also improves the regeneration performance of activated carbon. The phosphorus oxide structure formed by potassium dihydrogen phosphate during the activation process may help stabilize the pore structure of activated carbon, reduce irreversible adsorption or blockage of adsorbate during regeneration, and thus facilitate the recovery of adsorption sites. Comparative Example 2 omitted the microwave radiation activation step, and its regeneration efficiency was also low. This shows that microwave radiation activation, while promoting the uniform distribution of potassium dihydrogen phosphate, may also contribute to the stability of the activated carbon skeleton, making it less prone to structural collapse or pore blockage in repeated adsorption-desorption cycles, thereby improving regeneration efficiency and cycle life.

[0109] Comparative Example 3 uses different binders, and its regeneration performance is not as good as the example sample. The type and ratio of the binder affect the structural density and mechanical strength of the activated carbon precursor, and thus affect its structural stability during the regeneration process. A suitable binder can ensure that the activated carbon maintains its original pore structure during high-temperature desorption and multiple cycles, reducing pore damage, thereby maintaining a high regeneration efficiency. Comparative Example 4 is not acid-washed, and its regeneration efficiency is also low. Acid washing can remove inorganic impurities that may be present in the activated carbon pores. These impurities may change during the adsorption and regeneration process, resulting in pore blockage or adsorption site deactivation. Removing these impurities helps the activated carbon to desorb the adsorbate more thoroughly during the regeneration process and restore its adsorption capacity. The amount of potassium dihydrogen phosphate used in Comparative Example 5 is lower than the specific range, and its regeneration efficiency is significantly lower than that of the example sample, and after multiple cycles, the performance degradation is more obvious. This shows that only when the mass fraction of potassium dihydrogen phosphate is within the effective range can it fully exert its role in stabilizing the activated carbon structure and promoting regeneration efficiency. An appropriate amount of potassium dihydrogen phosphate helps maintain the microstructural integrity of the activated carbon during the cycle and prevent adsorption site passivation.

[0110] Experiment 3: Experimental purpose: To evaluate the crushing resistance and wear resistance of each sample of activated carbon.

[0111] Experimental steps: Crushing strength test: Sample preparation: Take the activated carbon sample to be tested, place it in a forced air drying oven at 105°C for 2 hours, and then cool it to room temperature.

[0112] Particle screening: Randomly select representative intact particles from the dry sample to ensure that the particle size meets the requirements and remove visible broken or incomplete particles.

[0113] Single Particle Test: Use a single particle crusher equipped with a pressure sensor and loading device. Place a single activated carbon particle between two parallel pressure plates. Apply pressure at a constant rate of 0.5 mm / min until the particle breaks for the first time. Record the maximum pressure value displayed by the pressure sensor at this point.

[0114] Repeat the test and calculate: Repeat the above test steps for no less than 100 individual particles, and calculate the arithmetic mean of the crushing strength of all the tested particles as the average crushing strength of the sample.

[0115] Wear resistance test: Sample preparation: Take about 50 g (accurate to 0.01 g) of dry activated carbon sample and record its initial mass.

[0116] Wear treatment: Place the sample in a standard wear test cylinder with an inner diameter of 150 mm and a length of 200 mm. Fix the wear test cylinder on a rotating device and rotate it continuously at a speed of 60 r / min for 30 minutes.

[0117] Sieving and weighing: After the abrasion treatment is complete, remove the sample from the cylinder and sieve it through a standard sieve with a pore size of 1.0 mm. Carefully collect and weigh the activated carbon particles retained on the sieve (i.e., those not abraded to a size smaller than 1.0 mm), and record their mass.

[0118] The experimental results are shown in Table 3.

[0119] Table 3: Activated carbon mechanical strength test results

[0120] According to the mechanical strength test results shown in Table 3, the activated carbon prepared using this technical solution exhibits excellent mechanical strength and wear resistance. The average crushing strength and wear rate of the activated carbon samples from Examples 1, 2, and 3 were significantly superior to those from Comparative Examples 1, 2, 3, 4, and 5. This demonstrates that the specific combination of biochar, binder, and preparation process employed in this technical solution effectively improves the structural integrity and mechanical stability of the activated carbon.

[0121] Comparative Example 1 was not immersed in potassium dihydrogen phosphate solution, and its mechanical strength was lower than that of the example sample, and the wear rate was higher. This shows that the introduction of potassium dihydrogen phosphate not only has a regulatory effect on the pore structure during the activation process, but may also enhance the overall structural strength of the activated carbon particles by interacting with the carbon skeleton. This enhancement helps the activated carbon resist external impact and friction during adsorption, regeneration and transportation, and reduces pulverization. Comparative Example 2 omitted the microwave radiation activation step, and its mechanical strength was also relatively low. This shows that microwave radiation activation may help potassium dihydrogen phosphate to penetrate more evenly and solidify in the pores and skeleton of the activated carbon, thereby forming a denser and stronger structure, improving its compression and wear resistance.

[0122] Comparative Example 3 uses different binder types and ratios of powder to binder, and its mechanical strength is significantly lower than that of the example samples. It is further confirmed that the selection and proportion of the binder in the present technical solution are key factors in ensuring that the activated carbon has good mechanical strength. Comparative Example 4 has not been pickled, and its mechanical strength is also relatively low. The pickling process can remove inorganic ash in the pores of the activated carbon. These ashes may form weak points inside the activated carbon, affecting its mechanical strength. Removing these impurities helps to form a purer and stronger carbon skeleton. The amount of potassium dihydrogen phosphate in Comparative Example 5 is lower than the specific range, and its mechanical strength is significantly reduced. This shows that an appropriate amount of potassium dihydrogen phosphate can effectively promote the formation and solidification of the internal structural network of the activated carbon, thereby giving the activated carbon higher mechanical strength and wear resistance, ensuring its long-term stability in practical applications.

[0123] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. An automatically regenerable activated carbon for oil and gas separation, characterized in that: The composition includes the following parts by weight: Biochar: 80-120 parts by mass; Binder: 20-40 parts by mass; Potassium dihydrogen phosphate: 1 part by mass to 5 parts by mass.

2. The self-regenerating activated carbon for oil and gas separation according to claim 1, characterized in that: The biochar is formed by carbonizing and activating biomass raw materials rich in cellulose, hemicellulose and lignin.

3. The self-regenerating activated carbon for oil-gas separation according to claim 1, characterized in that: The potassium dihydrogen phosphate is a modifier used for impregnating modified activated carbon.

4. The self-regenerating activated carbon for oil-gas separation according to claim 1, characterized in that: The binder is selected from starch, polyvinyl alcohol or coal tar pitch.

5. The self-regenerating activated carbon for oil-gas separation according to claim 4, characterized in that: The starch includes amylose and amylopectin, the mass ratio of the amylose to the amylopectin is in the range of 3:17-7:13, the alcoholysis degree of the polyvinyl alcohol is 85.0%-99.5%, the polymerization degree is 500-2500, the softening point of the coal tar pitch is 70°C-150°C, and the coking value is 45%-65%.

6. A process for preparing automatically regenerable activated carbon for oil and gas separation, applied to the automatically regenerable activated carbon for oil and gas separation according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. The biomass raw materials are conveyed into the grinder for mechanical crushing. The particle size of the powder is controlled. The target particle size range is 180-325 mesh, and the proportion of the powder passing the target particle size screen is not less than 95%. The powder is conveyed by the fan to the powder storage tank and sealed for standby use. S2. Mixing and kneading the material powder with a binder to obtain a paste, extruding the paste into granules, and drying, carbonizing and activating the granulated activated carbon granules to form activated carbon; S3, pre-treating the formed activated carbon, soaking the pre-treated activated carbon in a potassium dihydrogen phosphate solution, activating the soaked activated carbon by microwave radiation, and then filtering and drying to obtain modified activated carbon; S4. The modified activated carbon is cleaned with an acidic cleaning solution, washed with water, and the washed activated carbon is dehydrated and then dried to obtain a finished product.

7. The process for preparing automatically regenerable activated carbon for oil and gas separation according to claim 6, characterized in that: In step S2, the material powder and the binder are mixed and kneaded in a mass ratio of 3:1, the carbonization temperature is 300°C-550°C, and the activation temperature is 800°C-900°C.

8. The process for preparing automatically regenerable activated carbon for oil and gas separation according to claim 6, characterized in that: In step S3, the pretreatment of the formed activated carbon includes drying the activated carbon at a temperature of 100°C-120°C for 12-36 hours, the mass fraction of the potassium dihydrogen phosphate solution is 5%-15%, the soaking temperature is 50°C-70°C, and the soaking time is 12-36 hours.

9. The process for preparing automatically regenerable activated carbon for oil and gas separation according to claim 6, characterized in that: In step S3, the soaked activated carbon is activated by microwave radiation, and the microwave power is 400W-700W, and the radiation is performed for 30-60 minutes.

10. The process for preparing automatically regenerable activated carbon for oil and gas separation according to claim 6, characterized in that: The cleaning comprises heating the cleaning solution to 90° C.-100° C. and maintaining the temperature for 20-60 minutes. The acidic cleaning solution is a hydrochloric acid solution with a concentration of 3%-8%.

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