Carbon aerogel nanosuspension with emulsification function and preparation method and application thereof

Abstract

This invention discloses a carbon aerogel nanosuspension with emulsifying function, its preparation method, and its application. The preparation method of the carbon aerogel nanosuspension includes: adding an alkaline solution to an aqueous solution of a phenolic organic compound and stirring and mixing, then adding an aldehyde solution to carry out an addition reaction to obtain a benzene-based multi-component mixture; then stirring and mixing with an acid solution to carry out a condensation reaction, and then aging the resulting reaction product to obtain a wet gel; the wet gel is freeze-dried and carbonized to obtain a block carbon aerogel; finally, the block carbon aerogel is pulverized into nanoparticles and ultrasonically dispersed in water to obtain the carbon aerogel nanosuspension. The carbon aerogel nanosuspension prepared by this invention has good emulsifying function, can effectively reduce the viscosity of waste tire pyrolysis oil, and capture fly ash in waste tire pyrolysis oil.

Description

Technical Field

[0001] This invention belongs to the field of viscosity reduction technology for waste tire pyrolysis oil. Specifically, this invention relates to a carbon aerogel nanosuspension with emulsification function, its preparation method, and its application. Background Technology

[0002] Waste tires, often referred to as "black pollution," cause severe damage to the ecological environment. my country generates 13.9 million tons of waste tires, but only 5.45 million tons are recycled, less than 40%. The waste tire pyrolysis oil produced from waste tire pyrolysis is characterized by its complex composition, high calorific value, medium viscosity, and low ash and carbon residue. It can be used to recover high-value-added chemical products such as toluene and limonene, and can also be used as fuel oil for heating. However, fuel oil requires high fluidity and burnout, necessitating viscosity reduction and deashing treatment of the waste tire pyrolysis oil.

[0003] In view of this, the present invention is hereby proposed. Summary of the Invention

[0004] The purpose of this invention is to provide a carbon aerogel nanosuspension with emulsifying function, its preparation method and application. This carbon aerogel nanosuspension can reduce the viscosity of waste tire pyrolysis oil and capture fly ash in the waste tire pyrolysis oil.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, embodiments of the present invention provide a method for preparing a carbon aerogel nanosuspension with emulsifying function, comprising the following steps: (1) Add an alkaline solution to the aqueous solution of phenolic organic compounds until the pH of the solution system is 9±0.2. After stirring and mixing, add an aldehyde solution and continue stirring to carry out the addition reaction to obtain a benzene multi-component mixture. (2) Add acid solution to the benzene-based multi-component mixture until the pH of the mixture is 3±0.5, stir to carry out condensation reaction, and after the reaction is completed, age the resulting reaction product to obtain wet gel. (3) The wet gel is freeze-dried to obtain a dry gel; then the dry gel is carbonized to obtain a blocky carbon aerogel. (4) After crushing the block carbon aerogel into nanoparticle carbon aerogel, dissolve it in water and disperse it by ultrasonication to obtain the carbon aerogel nano suspension.

[0007] In some embodiments, in step (1), the concentration of the aqueous solution of the phenolic organic compound is 0.4-0.6 mol / L; Optionally, the phenolic organic compound includes at least one of resorcinol and phenol; And / or, the concentration of the alkaline solution is 0.05-0.15 mol / L; Optionally, the alkaline solution includes at least one of dilute ammonia water and sodium carbonate solution; And / or, the solubility of the aldehyde solution is 20-25%; Optionally, the aldehyde solution includes at least one of formaldehyde solution and furfural solution.

[0008] In some embodiments, in step (1), the mixing time is 30-60 min; And / or, the addition reaction is carried out at a temperature of 60-70°C for a time of 1-1.5 h.

[0009] In some embodiments, in step (2), the concentration of the acid solution is 0.4-0.6 mol / L; Optionally, the acid solution includes at least one of acetic acid solution and dilute hydrochloric acid solution.

[0010] In some embodiments, in step (2), the reaction temperature of the condensation reaction is 80-90°C and the reaction time is 1-1.5h; And / or, the reaction temperature of the aging treatment is 60-70℃, and the aging time is 2-3 days.

[0011] In some embodiments, step (2) further includes solvent replacement, which is performed after the reaction product has been aged for 1 day. The solvent replacement process is as follows: the reaction product after 1 day of aging is immersed in anhydrous ethanol, the exudate is replaced every 6-8 hours, and this step is repeated 3-4 times.

[0012] In some embodiments, in step (3), the freeze-drying temperature is -20~-40℃ and the drying time is 10-12h; And / or, the carbonization process is as follows: under a nitrogen atmosphere, the temperature is increased to 700-800℃ at a heating rate of 5-10℃ / min, and held at that temperature for 2-2.5h.

[0013] In some embodiments, in step (4), the particle size of the nanoparticle carbon aerogel is 15-25 nm; And / or, the ultrasonic dispersion time is 30-60 min.

[0014] Secondly, embodiments of the present invention also propose a carbon aerogel nanosuspension with emulsifying function, wherein the carbon aerogel nanosuspension with emulsifying function is prepared by the preparation method described in the first aspect.

[0015] Thirdly, the present invention also proposes an application of a carbon aerogel nano-suspension with emulsifying function as described in the second aspect, wherein the carbon aerogel nano-suspension is used to reduce viscosity and remove ash from waste tire pyrolysis oil.

[0016] The advantages and beneficial effects of the embodiments of the present invention are as follows: This invention provides an embodiment of a carbon aerogel nanosuspension with emulsifying function, which is then used to reduce viscosity and remove ash from waste tire pyrolysis oil. This suspension forms an oil-in-water / water-in-oil emulsion system with the waste tire pyrolysis oil, breaking down the continuous oil phase into tiny droplets with a particle size in the millimeter range. This weakens the intermolecular adhesion forces and improves the fluidity of the waste tire pyrolysis oil. Furthermore, the carbon aerogel nanosuspension possesses a rich porous structure, and the resulting physical adsorption (similar to activated carbon) can capture the small amount of fly ash particles remaining in the pyrolysis oil. These particles can then be separated from the composite system using separation technology, reducing the negative impact of fly ash on combustion equipment and combustion itself. In addition, any residual carbon aerogel nanoparticles in the emulsified waste tire pyrolysis oil can be discharged as CO2 gas during subsequent combustion, significantly improving fuel burnout rate and calorific value. Attached Figure Description

[0017] Figure 1 A process flow diagram of the preparation method of carbon aerogel nanosuspension with emulsifying function according to an embodiment of the present invention.

[0018] Figure 2 The image shows the original morphology of the waste tire pyrolysis oil sample from Experiment Example 1 under a super depth-of-field microscope with a magnification of X300.

[0019] Figure 3 The image shows the morphology of waste tire pyrolysis oil after treatment with carbon aerogel nanosuspension emulsification and water-based dye methylene blue in Experiment Example 1, under a super depth-of-field microscope with a magnification of X500.

[0020] Figure 4 This is a test diagram of the viscosity reduction performance of the carbon aerogel nanosuspension prepared in Example 1 of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0022] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0023] In this invention, when a value is described as a range, it should be understood that such disclosure includes disclosure of all possible subranges within that range, as well as specific numerical values ​​falling within that range, regardless of whether specific numerical values ​​or specific subranges are explicitly specified.

[0024] In this invention, the terms “comprising” and “including” and their various variations mean that other elements or wholes may be included but are not specifically described.

[0025] In this invention, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0026] Firstly, such as Figure 1 As shown in the embodiment of the present invention, a method for preparing a carbon aerogel nanosuspension with emulsifying function is proposed, comprising the following steps: (1) Add an alkaline solution to the aqueous solution of phenolic organic compounds until the pH of the solution system is 9±0.2. After stirring and mixing, add an aldehyde solution and continue stirring to carry out the addition reaction to obtain a benzene multi-component mixture. (2) Add acid solution to the benzene-based multi-component mixture until the pH of the mixture is 3±0.5, stir to carry out condensation reaction, and after the reaction is completed, age the resulting reaction product to obtain wet gel. (3) The wet gel is freeze-dried to obtain a dry gel; then the dry gel is carbonized to obtain a blocky carbon aerogel. (4) After crushing the block carbon aerogel into nanoparticle carbon aerogel, dissolve it in water and disperse it by ultrasonication to obtain the carbon aerogel nano suspension.

[0027] In some embodiments, in step (1), the concentration of the aqueous solution of the phenolic organic compound is 0.4-0.6 mol / L. The inventors have found that if the concentration of the aqueous solution of the phenolic organic compound is lower than 0.4 mol / L, the intermolecular distance of the organic raw materials will be too large, the crosslinking density after the addition-condensation reaction will be insufficient, and a continuous three-dimensional gel skeleton will not be formed. The carbon aerogel will be prone to skeleton collapse after subsequent carbonization. However, if the concentration is higher than 0.6 mol / L, the organic raw material molecules will be too dense, the local crosslinking will be excessive during the reaction, the pore size of the gel skeleton formed will be uneven, and a large number of small molecule by-products will be easily generated, resulting in a loose wet gel structure. Therefore, it is advantageous to control the concentration of the aqueous solution of the phenolic organic compound in the range of 0.4-0.6 mol / L in the embodiments of the present invention. Optionally, the phenolic organic compound includes at least one of resorcinol and phenol. Both resorcinol and phenol contain phenolic hydroxyl groups directly linked to a benzene ring in their molecular structures. These phenolic hydroxyl groups provide unique and highly efficient active sites for addition reactions under alkaline conditions and condensation reactions under acidic conditions. In alkaline environments, the phenolic hydroxyl groups are easily deprotonated to form O-nucleophilic groups, which can undergo directional electrophilic addition with aldehydes. In acidic environments, the phenolic hydroxyl groups can undergo intermolecular dehydration condensation to form stable methylene (-CH2-) and methylene-ether (-CH2OCH2-) bridging bonds, ultimately constructing a three-dimensional gel framework. Furthermore, compared to other aromatic compounds, resorcinol contains two ortho- and ortho-and-tho-phenolic hydroxyl groups, resulting in higher reactivity and the ability to rapidly form a uniform cross-linked structure. Phenol, on the other hand, is readily available and lower in cost, and both can form a high-porosity carbon framework during subsequent carbonization. And / or, the concentration of the alkaline solution is 0.05-0.15 mol / L; and the inventors have found that if the concentration of the alkaline solution is below 0.05 mol / L, sufficient OH groups cannot be provided for the deprotonation of phenolic hydroxyl groups. - Insufficient formation of O-nucleophilic groups leads to slow addition reactions and inadequate introduction of hydroxymethyl-CH2OH groups onto the benzene ring, resulting in insufficient active sites for subsequent condensation reactions. However, if the alkaline concentration exceeds 0.15 mol / L, the reaction system becomes too alkaline, which can cause aldehydes to undergo Cannizzaro self-polymerization, generating alcohols and carboxylic acids and consuming effective aldehyde raw materials. Simultaneously, phenols are easily oxidized to quinones, disrupting the reaction system. Therefore, controlling the concentration of the alkaline solution within the range of 0.05-0.15 mol / L is appropriate in this embodiment of the invention. Optionally, the alkaline solution includes at least one of dilute ammonia and sodium carbonate solution, both of which are weak alkaline regulators that can slowly adjust the pH of the solution to 9±0.2, thereby avoiding the oxidation of phenols and the rapid decomposition of aldehydes caused by strong alkalinity. Furthermore, dilute ammonia is volatile and sodium carbonate leaves no residue, so it will not introduce impurities into the subsequent reaction system. And / or, the solubility of the aldehyde solution is 20-25%; Optionally, the aldehyde solution includes at least one of formaldehyde solution and furfural solution. Both formaldehyde and furfural are small-molecule aldehydes with low steric hindrance, readily undergoing addition reactions with the O-nucleophilic groups of phenolic hydroxyl groups. Furthermore, formaldehyde and furfural exhibit good stability in aqueous solutions, with a solubility range of 20-25% ensuring an effective concentration of aldehydes in the reaction system, avoiding problems such as self-polymerization due to excessive aldehyde concentration or incomplete reaction due to excessive dilution. Formaldehyde exhibits the highest reactivity, rapidly introducing hydroxymethyl-CH2OH onto the benzene ring; while furfural, a biomass aldehyde, is environmentally friendly, and its furan ring can increase the pore diversity of the carbon skeleton after carbonization, enhancing adsorption performance.

[0028] In some embodiments, in step (1), the mixing time is 30-60 min; And / or, the reaction temperature of the addition reaction is 60-70℃, and the reaction time is 1-1.5h. The inventors found through research that if the addition reaction temperature is below 60℃, the addition reaction rate will be too slow, and the effective introduction of hydroxymethyl-CH2OH on the benzene ring cannot be completed within 1.5h, resulting in the loss of active sites for subsequent condensation reactions. However, if the temperature is above 70℃, it will cause aldehydes to easily self-polymerize in the alkaline system and phenols to react excessively locally, resulting in uneven composition of the benzene-based multi-component mixture. In addition, excessively high temperatures will cause local overheating of the reaction system, generating bubbles and affecting the uniformity of the subsequent gel skeleton. At the same time, if the reaction time is less than 1h, the addition reaction is insufficient; if it is longer than 1.5h, unnecessary side reactions will occur, consuming effective raw materials.

[0029] In some embodiments, in step (2), the concentration of the acid solution is 0.4-0.6 mol / L. If the concentration of the acid solution is less than 0.4 mol / L, then H + If the concentration is insufficient, the intermolecular dehydration condensation reaction rate of the phenolic hydroxyl group is too slow, and a stable bridging bond cannot be formed; however, if the acid solution concentration is higher than 0.6 mol / L, the acidity will be too strong, which will cause the already formed hydroxymethyl-CH2OH to hydrolyze, destroying the addition reaction product. At the same time, if the condensation reaction rate is too fast, the pore size of the formed gel skeleton will be too small and the distribution will be uneven. Optionally, the acid solution includes at least one of acetic acid solution and dilute hydrochloric acid solution; wherein, acetic acid is a weak acid, which can achieve precise pH adjustment, and dilute hydrochloric acid has a fast reaction rate. Both can meet the pH requirement of 3±0.5 for condensation reaction, and the acid radical ions will not undergo side reactions with the reaction system. They can be completely decomposed during carbonization, ensuring the purity of carbon aerogel.

[0030] In some embodiments, in step (2), the reaction temperature of the condensation reaction is 80-90°C and the reaction time is 1-1.5h. The inventors have found through research that if the condensation reaction temperature is below 80°C, the intermolecular bridging bonds will form slowly, and a continuous three-dimensional gel skeleton cannot be formed within 1.5h. However, if the reaction temperature is above 90°C, the condensation reaction rate will be too fast, resulting in excessive local cross-linking, uneven pore size of the gel skeleton, and the generation of a large number of small molecule byproducts, leading to a loose wet gel structure. At the same time, if the reaction time is less than 1h, the condensation reaction will be insufficient, and the cross-linking density of the gel skeleton will be low. However, if the reaction time is longer than 1.5h, the gel skeleton will be over-cross-linked, and the pore size will be too small. Therefore, it is advantageous to control the temperature and time of the condensation reaction within the above range in the embodiments of the present invention. And / or, the reaction temperature of the aging treatment is 60-70℃, and the aging time is 2-3 days. If the aging temperature is below 60℃, the movement rate of gel molecules will be too slow, and the skeleton rearrangement cannot be completed, resulting in low wet gel strength. However, if the aging temperature is above 70℃, the solvent in the wet gel will evaporate rapidly, leading to skeleton shrinkage. The aging time of 2-3 days can ensure sufficient skeleton rearrangement. Solvent replacement after 1 day can replace water in time after the skeleton is initially formed, avoiding pore shrinkage caused by subsequent drying.

[0031] In some embodiments, step (2) further includes solvent replacement, which is performed after the reaction product has been aged for 1 day. The solvent replacement process is as follows: the reaction product aged for 1 day is immersed in anhydrous ethanol, the exudate is replaced every 6-8 hours, and this step is repeated 3-4 times. Ethanol with low interfacial tension can replace the water in the wet gel network, thereby avoiding pore shrinkage and framework collapse caused by subsequent drying. At this point, the three-dimensional wet gel structure is basically formed.

[0032] In some embodiments, in step (3), the freeze-drying temperature is -20~-40℃ and the drying time is 10-12h. Through freeze-drying, the solvent evaporates, thereby obtaining a dry gel with a well-preserved skeleton. And / or, the carbonization process is as follows: under a nitrogen atmosphere, the temperature is increased to 700-800℃ at a heating rate of 5-10℃ / min, and held for 2-2.5 hours. Carbonization under a nitrogen atmosphere prevents oxidation of the carbon skeleton during the carbonization process; and controlling the heating rate within a slow range of 5-10℃ / min allows the organic components in the dry gel to decompose slowly, avoiding skeleton cracking and pore collapse caused by rapid heating. Furthermore, the inventors have found that if the carbonization temperature is below 700℃, the organic components will not decompose sufficiently, leaving a large number of heteroatoms in the carbon skeleton; however, if the temperature is above 800℃, the carbon skeleton will graphitize, resulting in a significant decrease in specific surface area and loss of emulsification and adsorption properties. Simultaneously, a holding time of 2-2.5 hours ensures complete decomposition of the organic components, forming a pure carbon skeleton. Insufficient holding time leads to incomplete decomposition; excessive holding time causes over-sintering of the carbon skeleton, resulting in decreased porosity.

[0033] In some embodiments, in step (4), the particle size of the nanoparticle carbon aerogel is 15-25 nm; And / or, the ultrasonic dispersion time is 30-60 min.

[0034] Ultrasonic dispersion can prevent large-scale particle aggregation. The hydrophobic -CH2- and -CH2OCH2- groups in the carbon aerogel framework prevent water molecules from penetrating the pores and associating with -OH groups on the particle surface to form intermolecular / intramolecular hydrogen bonds. These hydrogen bonds can generate significant interfacial tension, causing pore shrinkage. After solvent replacement, the -OH groups grafted onto the carbon aerogel particle surface promote the solubility of the nano-aerogel in water. Under the combined effect of these two factors, water molecules only wet the particle surface without damaging the pore structure, resulting in a semi-dissolved suspension of the carbon aerogel in water, thus obtaining a carbon aerogel nano-suspension.

[0035] Secondly, embodiments of the present invention also propose a carbon aerogel nanosuspension with emulsifying function, wherein the carbon aerogel nanosuspension with emulsifying function is prepared by the preparation method described in the first aspect.

[0036] Thirdly, the present invention also proposes an application of a carbon aerogel nano-suspension with emulsifying function as described in the second aspect, wherein the carbon aerogel nano-suspension is used to reduce viscosity and remove ash from waste tire pyrolysis oil.

[0037] Furthermore, the waste tire pyrolysis oil is obtained by first crushing waste rubber tires to obtain fragments, and then pyrolyzing the fragments under anaerobic conditions to obtain tar.

[0038] By using the aforementioned carbon aerogel nano-suspension with emulsifying function to emulsify the obtained tar, an oil-in-water / water-in-oil emulsion system can be formed, thereby reducing the viscosity of the tar. Furthermore, due to the porous structure of the carbon aerogel nano-suspension, it possesses excellent adsorption capacity, which can adsorb a small amount of fly ash and soot in the tar and capture and separate them from the system, thus simultaneously achieving viscosity reduction and ash removal of waste tire pyrolysis oil.

[0039] The following are non-limiting embodiments and comparative examples of the present invention. It should be noted that the schemes in the comparative examples are not prior art, but are only set up for comparison with the schemes in the embodiments, and are not intended to limit the present invention. Unless otherwise stated, all raw materials used in the embodiments and comparative examples are conventional commercially available products, or can be prepared by known methods. Furthermore, the experimental methods in the experimental examples that do not specify specific conditions are conventional methods and conditions well known in the art.

[0040] Example 1 The preparation method of a carbon aerogel nanosuspension with emulsifying function according to this embodiment includes the following steps: (1) Add 0.1 mol / L dilute ammonia solution to 0.5 mol / L resorcinol aqueous solution until the pH of the solution system is 9. After stirring and mixing for 45 min, add formaldehyde solution with a solubility of 22% and stir continuously at 65℃ for 1.2 h to carry out the addition reaction and obtain a benzene multi-component mixture. (2) Add acetic acid solution with a concentration of 0.5 mol / L to the above benzene multi-component mixture until the pH value of the mixture is 3, and then stir at 85℃ for 1.2 h to carry out condensation reaction. After the reaction is completed, place the obtained reaction product in a 65℃ water bath for 2.5 days. After aging for 1 day, immerse the wet gel in anhydrous ethanol and replace the exudate every 7 h for a total of 3 times to complete the solvent replacement. After aging, the wet gel is obtained. (3) The above wet gel was placed in a freeze dryer at -20℃ for 11 hours to obtain dry gel; then the dry gel was placed in a tube furnace and nitrogen was introduced. The temperature was raised to 750℃ at a rate of 8℃ / min and held for 2.2 hours for carbonization treatment to obtain block carbon aerogel. (4) After crushing the above block carbon aerogel into 20nm nanoparticle carbon aerogel, dissolve it in deionized water and ultrasonically disperse it for 45min to obtain a carbon aerogel nano suspension with emulsification function.

[0041] Example 2 The preparation method of a carbon aerogel nanosuspension with emulsifying function according to this embodiment includes the following steps: (1) Add sodium carbonate solution with a concentration of 0.05 mol / L to a phenol aqueous solution with a concentration of 0.4 mol / L until the pH value of the solution system is 9. After stirring and mixing for 30 min, add furfural solution with a solubility of 20% and stir continuously at 60℃ for 1 h to carry out the addition reaction to obtain a benzene multi-component mixture. (2) Add a 0.4 mol / L dilute hydrochloric acid solution to the above benzene-based multi-component mixture until the pH of the mixture is 3. Then stir at 80°C for 1 h to carry out the condensation reaction. After the reaction is completed, place the resulting reaction product in a 60°C water bath for 2 days. After 1 day of aging, immerse the wet gel in anhydrous ethanol and replace the exudate every 6 h for a total of 4 times to complete the solvent replacement. After aging, the wet gel is obtained. (3) The above wet gel was placed in a freeze dryer at -20℃ for 10h to obtain dry gel; then the dry gel was placed in a tube furnace and nitrogen was introduced. The temperature was raised to 700℃ at a rate of 5℃ / min and held for 2h for carbonization treatment to obtain block carbon aerogel. (4) After crushing the above block carbon aerogel into 15nm nanoparticle carbon aerogel, dissolve it in deionized water and ultrasonically disperse it for 30min to obtain a carbon aerogel nano suspension with emulsification function.

[0042] Example 3 The preparation method of a carbon aerogel nanosuspension with emulsifying function according to this embodiment includes the following steps: (1) Add a 0.12 mol / L dilute ammonia-sodium carbonate composite solution (volume ratio 1:1) to a 0.55 mol / L m-diphenol-phenol composite aqueous solution (volume ratio 1:1) until the pH of the solution system is 9. After stirring and mixing for 50 min, add a 24% formaldehyde-furfural composite solution (volume ratio 1:1) and stir continuously at 68℃ for 1.4 h to carry out the addition reaction and obtain a benzene-based multi-component mixture. (2) Add a 0.55 mol / L acetic acid-dilute hydrochloric acid composite solution (volume ratio 1:1) to the above benzene multi-component mixture until the pH of the mixture is 3. Then stir at 88℃ for 1.4 h to carry out the condensation reaction. After the reaction is completed, place the obtained reaction product in a 68℃ water bath for 2.8 days. After 1 day of aging, immerse the wet gel in anhydrous ethanol and replace the exudate every 7.5 h for a total of 4 times to complete the solvent replacement. After aging, the wet gel is obtained. (3) The above wet gel was placed in a freeze dryer at -20℃ for 11.5h to obtain dry gel; then the dry gel was placed in a tube furnace and nitrogen was introduced. The temperature was raised to 780℃ at a rate of 9℃ / min and held for 2.4h for carbonization treatment to obtain block carbon aerogel. (4) After crushing the above block carbon aerogel into 23nm nanoparticle carbon aerogel, dissolve it in deionized water and ultrasonically disperse it for 50min to obtain a carbon aerogel nano suspension with emulsification function.

[0043] Example 4 The preparation method of a carbon aerogel nanosuspension with emulsifying function according to this embodiment includes the following steps: (1) Add a dilute ammonia solution with a concentration of 0.15 mol / L to a 0.6 mol / L m-diphenol aqueous solution until the pH of the solution system is 9. After stirring and mixing for 60 min, add a formaldehyde-furfural composite solution with a solubility of 25% and stir continuously at 70℃ for 1.5 h to carry out the addition reaction and obtain a benzene-based multi-component mixture. (2) Add acetic acid solution with a concentration of 0.6 mol / L to the above benzene multi-component mixture until the pH value of the mixture is 3, and then stir at 90℃ for 1.5 h to carry out condensation reaction. After the reaction is completed, place the obtained reaction product in a 70℃ water bath for 3 days. After 1 day of aging, immerse the wet gel in anhydrous ethanol and replace the exudate every 8 h for a total of 3 times to complete the solvent replacement. After aging, the wet gel is obtained. (3) The above wet gel was placed in a freeze dryer at -20℃ for 12 hours to obtain dry gel; then the dry gel was placed in a tube furnace and nitrogen was introduced. The temperature was raised to 800℃ at a rate of 10℃ / min and held for 2.5 hours for carbonization treatment to obtain block carbon aerogel. (4) After crushing the above block carbon aerogel into 25nm nanoparticle carbon aerogel, dissolve it in deionized water and ultrasonically disperse it for 60min to obtain a carbon aerogel nano suspension with emulsification function.

[0044] Comparative Example 1 This comparative example provides a method for preparing a carbon aerogel nanosuspension, comprising the following steps: (1) Add a dilute ammonia solution with a concentration of 0.03 mol / L to a 0.7 mol / L resorcinol aqueous solution until the pH of the solution system is 9. After stirring and mixing for 20 min, add a formaldehyde solution with a solubility of 28% and stir continuously at 50℃ for 0.8 h to carry out the addition reaction and obtain a benzene-based multi-component mixture. (2) Add acetic acid solution with a concentration of 0.7 mol / L to the above benzene multi-component mixture until the pH value of the mixture is 3, then stir at 95℃ for 0.8 h to carry out condensation reaction. After the reaction is completed, place the obtained reaction product in a 55℃ water bath for 1.5 days. After aging for 1 day, immerse it in anhydrous ethanol. Replace the exudate every 9 h for a total of 2 times to complete the solvent replacement and obtain wet gel. (3) The above wet gel was dried in a freeze dryer at -20℃ for 8 hours to obtain dry gel; the dry gel was placed in a tube furnace and nitrogen gas was introduced to raise the temperature to 850℃ at a heating rate of 12℃ / min and held for 1.5 hours for carbonization treatment to obtain block carbon aerogel. (4) After crushing the above block carbon aerogel into 30nm nanoparticles, dissolve it in deionized water and ultrasonically disperse for 20min to obtain carbon aerogel nano suspension.

[0045] Compared to Example 1 of this invention, the emulsification function of the carbon aerogel nanosuspension prepared in Comparative Example 1 is significantly inferior to that in Example 1, and its deashing ability is greatly reduced. Specifically, this is because the concentration of organic raw materials used in Comparative Example 1 is too high, and the key process parameters such as acid and alkali solution concentration, reaction temperature, and time deviate from the parameter ranges defined in the embodiments of this invention. This results in insufficient addition-condensation reaction and excessive local crosslinking, leading to low porosity and uneven pore size distribution of the carbon aerogel skeleton. Consequently, it cannot form a stable oil-in-water emulsion with waste tire pyrolysis oil, and oil droplets easily... Agglomeration (particle size greater than 5 mm) ultimately resulted in a viscosity reduction rate of only 30% of that in Example 1 for the pyrolysis oil. Furthermore, the carbonization heating rate of Comparative Example 1 was too fast and the holding time was insufficient, causing the porous structure of the carbon aerogel to collapse and the specific surface area to decrease significantly. This resulted in a weak physical adsorption capacity for fly ash in the pyrolysis oil, with a fly ash collection rate of only 25% of that in Example 1. In addition, due to insufficient ultrasonic dispersion time in Comparative Example 1, the carbon aerogel nanoparticles agglomerated severely, resulting in poor suspension stability. After standing for 2 hours, stratification and precipitation occurred, making it impossible to achieve uniform mixing with the pyrolysis oil.

[0046] Comparative Example 2 This comparative example provides a method for preparing a carbon-based nano suspension, comprising the following steps: (1) Add a dilute ammonia solution with a concentration of 0.1 mol / L to a urea solution with a concentration of 0.5 mol / L until the pH of the solution system is 9. After stirring and mixing for 45 min, add a formaldehyde solution with a solubility of 22% and continue stirring at 65℃ for 1.2 h to carry out the reaction and obtain a mixed system. (2) Add acetic acid solution with a concentration of 0.5 mol / L to the above mixed system until the pH value of the system is 3, then stir at 85℃ for 1.2 h. After the reaction is completed, place the obtained product in a 65℃ water bath for 2.5 days. After aging for 1 day, immerse it in anhydrous ethanol. Replace the exudate every 7 h for a total of 3 times to complete the solvent replacement and obtain a gel-like product. (3) The above gel-like product was dried in a freeze dryer at -20℃ for 11h to obtain a dry gel; the dry gel was placed in a tube furnace and nitrogen gas was introduced to raise the temperature to 750℃ at a heating rate of 8℃ / min and held for 2.2h for carbonization treatment to obtain a blocky carbon-based product. (4) After crushing the above block carbon-based product into 20 nm nanoparticles, dissolve it in deionized water and ultrasonically disperse for 45 min to obtain a carbon-based nano suspension.

[0047] The carbon-based nano-suspension prepared in Comparative Example 2 completely lacks emulsification function and has almost no deashing ability. The core reason is that urea lacks phenolic hydroxyl groups and cannot undergo addition-condensation reactions dependent on phenolic hydroxyl groups. Urea and formaldehyde only undergo simple amine-aldehyde condensation and cannot form a three-dimensional cross-linked gel framework. The carbon-based product obtained after carbonization has an irregular porous structure but is a dense blocky particle, which cannot reduce the interfacial tension between waste tire pyrolysis oil and water, cannot form an emulsion, and the viscosity of the pyrolysis oil does not change significantly. Moreover, the dense carbon-based product has no effective adsorption pores and has no ability to capture fly ash in the pyrolysis oil. Under a microscope, a large number of black fly ash particles can be observed, which are not significantly different from untreated waste tire pyrolysis oil. In addition, the surface of the carbon-based product lacks hydrophilic / hydrophobic synergistic active groups, has poor dispersibility in water, and the suspension completely separates after standing for 1 hour, making it unsuitable for the treatment of waste tire pyrolysis oil.

[0048] Experimental Example 1 Waste rubber tires are first crushed to obtain scrap, which is then pyrolyzed under anaerobic conditions to obtain pyrolysis oil. This waste tire pyrolysis oil is then emulsified using the carbon aerogel nano-suspension with emulsifying function prepared in Example 1, and finally dyed with the water-based dye methylene blue.

[0049] The results are as follows Figure 2-3 As shown, where, Figure 2 The above-mentioned waste tire pyrolysis oil sample is shown under a super depth-of-field microscope with a magnification of X300. Among them, the white and sticky ones are oil droplets, and the black irregular ones are tiny carbon particles remaining in the pyrolysis oil. Figure 3The image shows the morphology of the upper emulsion of waste tire pyrolysis oil after emulsification with carbon aerogel nanosuspension and staining with the water-based dye methylene blue, under a super depth-of-field microscope at a magnification of X500. The blue continuous phase in the image represents water, and the scattered white particles represent the emulsified waste tire pyrolysis oil. This indicates that the emulsion system is a typical oil-in-water emulsion, with oil droplet diameters less than 2 mm and good dispersion, demonstrating the good emulsification effect and stability of the carbon aerogel nanosuspension. Furthermore, the carbon particles / fly ash originally present in the original oil sample were adsorbed into the carbon aerogel, and no obvious black carbon particles / fly ash were observed under the microscope, proving that the carbon aerogel nanosuspension system has a good capture ability for carbon particles / fly ash in waste tire pyrolysis oil.

[0050] Experimental Example 2 A suitable amount of waste tire pyrolysis oil was placed in an etched glass channel model. Then, the carbon aerogel nano-suspension with emulsifying function prepared in Example 1 was injected at the inlet, allowing it to mix and contact with the waste tire pyrolysis oil sample within the micropores. The morphology of this sample under a super depth-of-field microscope with a magnification of X500 is shown in the image below. Figure 4 As shown in the figure, the pyrolysis oil sample was broken into highly spherical oil droplets by the shearing and emulsification of the carbon aerogel nanoparticles in the carbon aerogel nanosuspension. These droplets were dispersed in narrow channels, demonstrating that the carbon aerogel nanosuspension can significantly reduce the oil-water interfacial tension, promote emulsification and viscosity reduction of the pyrolysis oil, and improve its fluidity.

[0051] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0052] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a carbon aerogel nanosuspension with emulsifying function, characterized in that, Includes the following steps: (1) Add an alkaline solution to the aqueous solution of phenolic organic compounds until the pH of the solution system is 9±0.

2. After stirring and mixing, add an aldehyde solution and continue stirring to carry out the addition reaction to obtain a benzene multi-component mixture. (2) Add acid solution to the benzene-based multi-component mixture until the pH of the mixture is 3±0.5, stir to carry out condensation reaction, and after the reaction is completed, age the resulting reaction product to obtain wet gel. (3) The wet gel is freeze-dried to obtain a dry gel; The dry gel is then carbonized to obtain a blocky carbon aerogel. (4) After crushing the block carbon aerogel into nanoparticle carbon aerogel, dissolve it in water and disperse it by ultrasonication to obtain the carbon aerogel nano suspension.

2. The method for preparing the carbon aerogel nanosuspension with emulsifying function according to claim 1, characterized in that, In step (1), the concentration of the aqueous solution of the phenolic organic compound is 0.4-0.6 mol / L; Optionally, the phenolic organic compound includes at least one of resorcinol and phenol; And / or, the concentration of the alkaline solution is 0.05-0.15 mol / L; Optionally, the alkaline solution includes at least one of dilute ammonia water and sodium carbonate solution; And / or, the solubility of the aldehyde solution is 20-25%; Optionally, the aldehyde solution includes at least one of formaldehyde solution and furfural solution.

3. The method for preparing the carbon aerogel nanosuspension with emulsifying function according to claim 1, characterized in that, In step (1), the mixing time is 30-60 minutes; And / or, the addition reaction is carried out at a temperature of 60-70°C for a time of 1-1.5 h.

4. The method for preparing the carbon aerogel nanosuspension with emulsifying function according to claim 1, characterized in that, In step (2), the concentration of the acid solution is 0.4-0.6 mol / L; Optionally, the acid solution includes at least one of acetic acid solution and dilute hydrochloric acid solution.

5. The method for preparing the carbon aerogel nanosuspension with emulsifying function according to claim 1, characterized in that, In step (2), the reaction temperature of the condensation reaction is 80-90℃ and the reaction time is 1-1.5h; And / or, the reaction temperature of the aging treatment is 60-70℃, and the aging time is 2-3 days.

6. The method for preparing the carbon aerogel nanosuspension with emulsifying function according to claim 1, characterized in that, Step (2) also includes solvent replacement, which is carried out after the reaction product has been aged for 1 day. The solvent replacement process is as follows: the reaction product after 1 day of aging is soaked in anhydrous ethanol, the exudate is replaced every 6-8 hours, and this step is repeated 3-4 times.

7. The method for preparing the carbon aerogel nanosuspension with emulsifying function according to claim 1, characterized in that, In step (3), the freeze-drying temperature is -20~-40℃ and the drying time is 10-12h; And / or, the carbonization process is as follows: under a nitrogen atmosphere, the temperature is increased to 700-800℃ at a heating rate of 5-10℃ / min, and held at that temperature for 2-2.5h.

8. The method for preparing the carbon aerogel nanosuspension with emulsifying function according to claim 1, characterized in that, In step (4), the particle size of the nanoparticle carbon aerogel is 15-25 nm. And / or, the ultrasonic dispersion time is 30-60 min.

9. A carbon aerogel nanosuspension with emulsifying function, characterized in that, The carbon aerogel nanosuspension is prepared by the preparation method according to any one of claims 1-8.

10. An application of the carbon aerogel nanosuspension with emulsifying function as described in claim 9, characterized in that, The carbon aerogel nanosuspension was used to reduce viscosity and remove ash from waste tire pyrolysis oil.

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