An active carbon fine powder composite additive for reducing asphalt VOCs
By modifying the asphalt with activated carbon micro powder composite additives, the problems of VOCs release and anti-aging in asphalt were solved, the high-temperature stability and rutting resistance of asphalt were improved, and the dispersibility and storage stability of the powder were improved, achieving dust-free processing.
Patent Information
- Application Number
- CN202611143987.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-30
- Publication Date
- 2026-11-06
AI Technical Summary
Existing asphalt additives release volatile organic compounds (VOCs) severely during high-temperature mixing and paving, and are difficult to maintain anti-aging and anti-rutting properties under high temperature and light heat environments. At the same time, powder additives are prone to dust and stratification during processing and storage.
Activated carbon micro powder composite additives are used to prepare activated carbon micro powder by co-thermal decomposition modification of eutectic solvent precursors and transition metal salts. Combined with layered silicates, hindered amine light stabilizers and antioxidants, a porous structure and active sites are formed to enhance adsorption capacity and interfacial compatibility. Stepwise premixing and thermal blending granulation processes are used to improve dispersibility.
It significantly reduces VOCs release, improves the high-temperature structural stability and rutting resistance of asphalt, enhances its resistance to photo-oxidative aging, and improves its processing and storage stability, achieving dust-free dispersion.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of asphalt additives, and more particularly to an activated carbon micron powder composite additive for reducing VOCs in asphalt. Background Technology
[0002] Asphalt, a widely used cementing material in road engineering, is prone to thermal decomposition and oxidation reactions during high-temperature mixing, paving, and long-term service. This releases large amounts of asphalt fumes and volatile organic compounds (VOCs, such as benzene compounds BTEX and low-molecular-weight polycyclic aromatic hydrocarbons PAHs). These volatile substances not only cause serious air pollution and threaten the health of construction workers and surrounding residents, but the continuous release of lightweight components also accelerates the deterioration of the asphalt material itself.
[0003] To reduce VOCs release from asphalt and improve its road performance, existing technologies often introduce adsorbent powders (such as porous activated carbon and bentonite) or polymer modifiers into the asphalt. However, existing asphalt additives and related control technologies still have the following significant technical defects and bottlenecks: Porous adsorption materials have poor physical adsorption thermal stability and low selectivity: Traditional adsorbents such as activated carbon mainly rely on weak physical van der Waals forces to capture volatiles. During the high-temperature mixing and paving stages of asphalt (usually 150℃~180℃), the adsorbed low-molecular-weight organic matter is prone to secondary desorption and secondary release. Moreover, the unmodified carbon-based surface lacks specific active sites, and the interfacial forces on benzene compounds and aromatic polar components are weak, making it impossible to achieve deep locking of characteristic VOCs.
[0004] Single-function additives cannot simultaneously address both anti-aging and high-temperature rutting resistance: Asphalt faces a complex aging mechanism under the combined effects of thermo-oxidative and photo-oxidative processes during its service life. Traditional methods relying solely on single antioxidants or light stabilizers are insufficient to cope with the free radical chain reactions induced by high-temperature thermal oxidation and ultraviolet radiation. Simultaneously, inorganic fillers exhibit poor interfacial compatibility with the asphalt matrix, easily leading to secondary agglomeration within the asphalt. This hinders the construction of a continuous stress transmission and molecular barrier network, resulting in insufficient viscoelasticity of the asphalt at high temperatures and making it difficult to significantly improve the pavement's rutting resistance.
[0005] The challenges of processing, dispersibility, and dust-free production of powder additives: Porous powder materials have a large specific surface area and low density, which easily generate serious dust during direct feeding and mixing. This not only causes material loss and environmental pollution, but also makes it difficult for powder particles to achieve homogeneous dispersion at the microscopic level in high-viscosity asphalt systems. During long-term storage, sedimentation and stratification are likely to occur, which seriously affects the stable performance of the functional components of the additives.
[0006] Therefore, how to develop a composite additive that can achieve efficient and high thermal stability adsorption and locking of asphalt VOCs, improve the anti-aging and anti-rutting properties of asphalt under high temperature and light-heat environments, and at the same time have good processing compatibility and dust-free characteristics is a technical problem that urgently needs to be solved in the field of asphalt modification technology. Summary of the Invention
[0007] The first objective of this invention is to provide an activated carbon micron powder composite additive, comprising the following components by mass percentage: Composite modified activated carbon micro powder: 65%-75%; Layered silicates: 12%-18%; Hindered amine light stabilizers: 4%-8%; Antioxidant: 3%-7%; Surface compatibility modifier: 1%-3%; The composite modified activated carbon micro powder is obtained by modifying the activated carbon micro powder matrix by co-pyrolysis of a eutectic solvent precursor and a transition metal salt under an inert atmosphere. The eutectic solvent precursor is formed by the condensation of anhydrous choline chloride and a nitrogen-containing hydrogen bond donor, wherein the nitrogen-containing hydrogen bond donor is selected from urea and / or thiourea. In preparing the composite modified activated carbon micro powder, the mass ratio of the activated carbon micro powder matrix, the nitrogen-containing hydrogen bond donor, and the transition metal salt is 100:100-130:3-6, wherein the transition metal salt is anhydrous cuprous chloride or anhydrous ferric chloride.
[0008] Preferably, the layered silicate is at least one of montmorillonite, layered kaolinite, and lithium diatomite.
[0009] Preferably, the hindered amine light stabilizer is a polymeric hindered amine light stabilizer with a thermal weight loss of ≤5% at 200°C.
[0010] Preferably, the antioxidant is a composite antioxidant system composed of a primary antioxidant and an auxiliary antioxidant; The primary antioxidant contains stereohindered phenols; the secondary antioxidant is a trivalent phosphorus phosphite compound; the mass ratio of the primary antioxidant to the secondary antioxidant is 1:1.5-2.5.
[0011] Preferably, the surface compatibility modifier is a titanate coupling agent and / or a stearic acid derivative.
[0012] Preferably, the composite modified activated carbon micro powder is prepared by the following steps: S1 mixes anhydrous choline chloride with a nitrogen-containing hydrogen bond donor and performs a condensation reaction to obtain a eutectic solvent precursor; then a transition metal salt is added to perform a complexation reaction. S2, mix the product after the reaction in step S1 with the activated carbon micro powder matrix, dry, and obtain carbon powder precursor. S3, the carbon powder precursor is placed in an inert atmosphere and subjected to co-pyrolysis modification at 550-650℃.
[0013] In step S1, the temperature of both the condensation reaction and the complexation reaction is 90-110℃, and the time of the complexation reaction is 0.5-1.5h. In step S2, the activated carbon micro powder matrix is pre-dispersed in anhydrous ethanol and ultrasonically dispersed; After the reaction in step S3 is completed, the resulting product is washed until neutral and dried.
[0014] The second objective of this invention is to provide a method for preparing the aforementioned activated carbon micron powder composite additive, comprising the following steps: S1: Mix the composite modified activated carbon micro powder and the layered silicate; then introduce the surface compatibility modifier and stir-premix to form an oleophilic transition layer on the powder surface; to obtain a mixture. S2: Add the hindered amine light stabilizer and the antioxidant to the mixture obtained in step S1, and heat to 115-125°C for thermal blending to obtain the agglomeration precursor; S3: The agglomeration precursor obtained in step S2 is fed into a molding machine and granulated at 120-130℃, then cooled and crushed to obtain the activated carbon micro powder composite additive.
[0015] Preferably, in step S1, the stirring and premixing speed is 1500-2000 rpm; In step S3, the particle size of the activated carbon micro powder composite additive is controlled to be 0.1-0.5 mm.
[0016] The third objective of this invention is to provide the application of the aforementioned activated carbon micro powder composite additive in the preparation of asphalt, wherein the amount of activated carbon micro powder composite additive incorporated is 0.15%-0.45% based on 100% of the mass of the asphalt mixture.
[0017] The beneficial technical effects of the present invention are as follows: (1) Efficiently regulate the emission of asphalt fumes and volatile organic compounds (VOCs).
[0018] This invention successfully constructs a composite modified activated carbon micropowder with abundant porous structure and active coordination centers on a carbon-based framework through the co-pyrolysis reaction of a eutectic solvent precursor and a transition metal salt. This modified micropowder utilizes a well-developed pore network to physically trap volatile components such as benzene compounds and low-molecular-weight aromatic hydrocarbons released during hot-mix asphalt production. Furthermore, the nitrogen-containing functional groups and uniformly distributed transition metal active sites on the carbon surface can interact strongly with aromatic volatiles, significantly improving adsorption-locking stability under high-temperature conditions. Combined with the tortuous physical barrier network constructed by layered silicates, it effectively hinders the diffusion and migration of lightweight components to the asphalt surface. Through a multi-synergistic mechanism of physical and chemical adsorption and interfacial barrier, the release of flue gas and VOCs during asphalt construction is significantly reduced. (2) Significantly enhances the high-temperature structural stability and rutting resistance of asphalt mixtures.
[0019] The high specific surface area and well-developed pores of composite modified activated carbon micropowder can selectively adsorb free lightweight components in asphalt, promoting the transformation of free asphalt into structured asphalt, thereby enhancing the viscoelastic properties of the asphalt matrix. Furthermore, layered silicates modified with surface compatibility modifiers can achieve exfoliation and uniform dispersion within the asphalt phase. Their lamellar network not only restricts the volatilization and migration of lightweight components but also effectively constrains the relative slippage of asphalt polymer chains under high temperature and dynamic loads. The porous carbon powder and layered inorganic phase intertwine and synergistically enhance the overall stiffness and deformation resistance of the system while maintaining excellent structural continuity, significantly improving the asphalt pavement's resistance to high-temperature rutting deformation. (3) It has excellent thermal oxygen and ultraviolet light oxygen anti-aging durability.
[0020] The activated carbon micropowder modified by co-thermal decomposition not only retains its excellent specific surface area, but the nitrogen functional groups and active centers introduced on its surface also enhance its ability to remove and adsorb aging media such as free radicals and peroxide intermediates. Furthermore, by combining a high-temperature resistant polymerizable hindered amine light stabilizer with a composite antioxidant system consisting of stereohindered phenols (used to capture free radicals and interrupt free radical chain proliferation) and trivalent phosphorus phosphite (used for efficient decomposition of hydrogen peroxide), these three components, together with the modified activated carbon micropowder, form a complementary anti-aging protective network, comprehensively blocking the degradation process of asphalt under the cross-linking effects of light, heat, and oxygen, and significantly extending the service life of asphalt materials. (4) Excellent dust-free processing performance, dispersion compatibility and storage stability.
[0021] This invention employs a stepwise premixing and hot blending granulation process. First, a surface compatibility modifier is used to reduce the surface energy of the inorganic powder, constructing an oleophilic transition layer that significantly improves the interfacial affinity between the inorganic powder and the organic asphalt matrix. Then, a low-melting-point hindered stabilizer and antioxidant are combined for hot blending, encapsulation, and granulation to obtain a micro-homogeneous granular additive. This morphology not only completely solves the problems of dust and material loss during powder transportation, weighing, and feeding, but also inhibits secondary agglomeration and sedimentation stratification of inorganic particles in asphalt, ensuring rapid and uniform dispersion and efficient utilization of the additive during high-temperature mixing. Detailed Implementation
[0022] To better understand the present invention, the present invention will be further described below with reference to specific serial numbers. The terminology used in the serial numbers is for describing specific embodiments and does not constitute a limitation on the scope of protection of the present invention.
[0023] In the specific implementation methods, unless otherwise specified, the experimental methods used are all conventional methods, and the materials and reagents used are all commercially available unless otherwise specified.
[0024] Unless otherwise specified, percentages, % and so on in the specific implementation method are assumed to be mass percentages.
[0025] Example 1: Preparation of Composite Modified Activated Carbon Micropowder Step 1: Condensation of eutectic solvent precursors and complexation with transition metal salts Weigh anhydrous choline chloride and nitrogen-containing hydrogen bond donor urea to a molar ratio of 1:2.
[0026] The two were mixed and subjected to a condensation reaction at 90°C. After complete eutectic melting, a homogeneous and transparent eutectic solvent precursor was obtained.
[0027] Subsequently, anhydrous cuprous chloride (as a transition metal salt) was introduced into the eutectic solvent precursor, and the complexation reaction was carried out continuously at 90°C for 0.5 h to obtain a metal-eutectic solvent complex solution.
[0028] In this step, the mass ratio of the relevant components is controlled as follows: 100g activated carbon micro powder matrix, 100g urea (containing nitrogen hydrogen bond donor), and 3g anhydrous cuprous chloride (transition metal salt).
[0029] Step 2: Liquid-phase mixing and drying of carbon powder precursor Take an appropriate amount of anhydrous ethanol, pre-disperse 100g of activated carbon micro powder matrix in anhydrous ethanol, transfer it into an ultrasonic cleaner for ultrasonic dispersion, so as to form a uniform carbon powder suspension.
[0030] Under mechanical stirring, all the metal-eutectic solvent complex liquid prepared in step one was slowly added to the carbon powder suspension. After mixing evenly, it was placed in an oven for drying to completely remove the anhydrous ethanol solvent, finally obtaining a solid-state encapsulated carbon powder precursor.
[0031] Step 3: Co-pyrolysis modification and post-treatment under an inert atmosphere The solid carbon powder precursor obtained from drying in step two is placed in a tube furnace, and high-purity nitrogen is continuously introduced to maintain the inert atmosphere of the entire system.
[0032] Start the heating program, control the heating rate, heat the system temperature to 550°C, and carry out the co-thermal decomposition modification reaction at a constant temperature of 550°C.
[0033] The pyrolysis reaction was stopped after 2 hours. The reaction product was then removed after natural cooling to room temperature under a nitrogen atmosphere. The crude product was repeatedly washed with deionized water until the pH of the washing filtrate was neutral (pH=7.0). The washed powder was then thoroughly dried in a vacuum drying oven to obtain composite modified activated carbon micro powder A.
[0034] Example 2: Preparation of Composite Modified Activated Carbon Micropowder Step 1: Condensation of eutectic solvent precursors and complexation with transition metal salts Anhydrous choline chloride and nitrogen-containing hydrogen bond donor thiourea were weighed in a molar ratio of 1:2. The two were mixed and subjected to a condensation reaction at 110°C. After complete eutectic melting, a homogeneous and transparent eutectic solvent precursor was obtained.
[0035] Subsequently, anhydrous ferric chloride (as a transition metal salt) was introduced into the eutectic solvent precursor, and the complexation reaction was carried out continuously at 110°C for 1.5 h to obtain a metal-eutectic solvent complex solution.
[0036] In this step, the mass ratio of the relevant components is controlled as follows: 100g activated carbon micro powder matrix, 130g thiourea (containing nitrogen hydrogen bond donor), and 6g anhydrous ferric chloride (transition metal salt).
[0037] Step 2: Liquid-phase mixing and drying of carbon powder precursor Take an appropriate amount of anhydrous ethanol, pre-disperse 100g of activated carbon micro powder matrix in anhydrous ethanol, transfer it into an ultrasonic cleaner for ultrasonic dispersion, so as to form a uniform carbon powder suspension.
[0038] Under mechanical stirring, all the metal-eutectic solvent complex liquid prepared in step one was slowly added to the carbon powder suspension. After mixing evenly, it was placed in an oven for drying to completely remove the anhydrous ethanol solvent, finally obtaining a solid-state encapsulated carbon powder precursor.
[0039] Step 3: Co-pyrolysis modification and post-treatment under an inert atmosphere The solid carbon powder precursor obtained from drying in step two is placed in a tube furnace, and high-purity argon gas is continuously introduced to maintain the inert atmosphere of the entire system.
[0040] Start the heating program, control the heating rate, heat the system to 650°C, and carry out the co-thermal decomposition modification reaction at a constant temperature of 650°C.
[0041] The pyrolysis reaction was stopped after 4 hours. The reaction product was then removed after natural cooling to room temperature under an argon protective atmosphere. The crude product was repeatedly washed with deionized water until the pH of the washing filtrate was neutral (pH=7.0). The washed powder was then thoroughly dried in a vacuum drying oven to obtain composite modified activated carbon micro powder B.
[0042] Application Example 1: Preparation of Activated Carbon Micropowder Composite Additive Step 1: Powder surface oleophilicity pretreatment Weigh each powder raw material according to the formula ratio. Based on a final total mass of 100 parts of activated carbon micron powder composite additive, the net weights of each component are as follows: Core functional adsorption source: Composite modified activated carbon micro powder A: 65 parts; Layered silicates: Montmorillonite: 18 parts; Surface compatibility modifier: titanate coupling agent: 1 part.
[0043] 65 parts of the weighed composite modified activated carbon micro powder A and 18 parts of montmorillonite were added to a high-speed mixer. Mechanical stirring was started, and the stirring speed was controlled at 1500 rpm. While running at 1500 rpm, the system was heated to 80°C. Under this condition, stirring and premixing were continued for 15 minutes to form a uniform oleophilic transition layer on the powder surface, thus obtaining the inorganic powder premix.
[0044] Step 2: Thermal blending and coating of low-melting-point hindered stabilizer Continue to introduce the following metered stabilizer components into the premix in the aforementioned high-speed mixer: Hindered amine light stabilizer: Polymerized hindered amine light stabilizer: 9 parts Antioxidant: A composite antioxidant system consisting of a primary antioxidant (antioxidant 1010) and a secondary antioxidant (antioxidant 168): 7 parts. The mass ratio of the primary antioxidant to the secondary antioxidant is controlled at 1:1.5.
[0045] After the materials are added, the mixing system is heated to 115°C for thermal blending. At this temperature, the components are bound together using their micro-melting properties, and the stirring reaction continues, thereby obtaining a uniformly distributed agglomerated precursor.
[0046] Step 3: Gentle extrusion molding and granulation The agglomeration precursor prepared in step two is continuously and quantitatively fed into a single-screw extruder (forming machinery). The length-to-diameter ratio of the extruder and the screw combination are controlled, and the electric heating jacket is adjusted to maintain the processing temperature of the forming and granulation section at 120°C.
[0047] The material is hot-extruded through a die and then naturally cooled to room temperature via an air-cooling line. It is then fed into a micro-crusher for physical crushing, and the discharged material enters a grading vibrating screen. By adjusting the mesh size of the front and rear screens, the final particle size of the resulting activated carbon micro-powder composite additive is controlled to 0.1 mm, thus completing the preparation of the entire dust-free activated carbon micro-powder composite additive product.
[0048] Application Example 2: Preparation of Activated Carbon Micropowder Composite Additive This application example serves as a comparison with Application Example 1 for forming the carbon source and inorganic framework. The only difference between it and Application Example 1 is: Core functional adsorption source: The composite modified activated carbon micro powder A prepared in Example 1 is replaced in equal amount with the composite modified activated carbon micro powder B prepared in Example 2.
[0049] Layered silicates: replaced with an equal amount of layered kaolin.
[0050] The remaining process steps and proportioning parameters, such as surface oleophilic pretreatment, thermal blending and coating, and molding and granulation, are exactly the same as those in Application Example 1.
[0051] Application Example 3: Preparation of Activated Carbon Micropowder Composite Additive The difference between it and application example 1 is that: Composite modified activated carbon micro powder A: 70 parts; layered silicate (lithium diatomite selected): 15 parts; hindered amine light stabilizer: 6 parts; antioxidant: 6 parts (of which the mass ratio of main and auxiliary antioxidants is 1:2.0); surface compatibility modifier: 3 parts.
[0052] Process control values: In step S1, the stirring and premixing temperature is 85°C and the rotation speed is 1750 rpm; in step S2, the thermal blending temperature is 120°C; in step S3, the molding and granulation temperature is 125°C and the finished product particle size is controlled at 0.3 mm.
[0053] Application Example 4: Preparation of Activated Carbon Micropowder Composite Additive The difference between it and application example 1 is as follows: The maximum balance of the formula is as follows: Composite modified activated carbon micro powder A: 75 parts; Layered silicate (montmorillonite): 12 parts; Hindered amine light stabilizer: 8 parts; Antioxidant: 3 parts (of which the mass ratio of main and auxiliary antioxidants is taken as the upper limit of 1:2.5); Surface compatibility modifier: 2 parts.
[0054] Process upper limit control: In step S1, the stirring and premixing temperature is 90°C and the rotation speed is 2000rpm; in step S2, the thermal blending temperature is 125°C; in step S3, the molding and granulation temperature is 130°C and the finished product particle size is controlled at 0.5mm.
[0055] Application Example 5: Preparation of Activated Carbon Micropowder Composite Additive The only difference between it and application example 1 is that: Core functional adsorption source: The composite modified activated carbon micro powder A prepared in Example 1 is replaced by an equal amount of ordinary commercially available activated carbon micro powder (without any in-situ doping or metal modification treatment).
[0056] The proportions of the remaining components in the additives and the complete set of thermal blending and granulation process parameters are exactly the same as those in Application Example 1.
[0057] Application Example 6: Preparation of Activated Carbon Micropowder Composite Additive The difference between this and Application Example 1 is that no layered silicates are added to the formula, and the missing mass ratio is made up by an equal amount of composite modified activated carbon micro powder A.
[0058] Application Example 7: Preparation of Activated Carbon Micropowder Composite Additive The difference between this and Application Example 1 is that no hindered amine light stabilizer is added to the formulation, and the missing mass ratio is made up by an equal amount of composite modified activated carbon micro powder A.
[0059] Application Example 8: Preparation of Activated Carbon Micropowder Composite Additive The difference between this and application example 1 is that no antioxidants are added to the formulation, and the missing mass ratio is made up by an equal amount of composite modified activated carbon micro powder A: Application Example 9: Preparation of Activated Carbon Micropowder Composite Additive The difference between this and application example 1 is that no surface compatibility modifier is added to the formulation, and the missing mass ratio is made up by an equal amount of composite modified activated carbon micro powder A: Test Example 1: Application and Performance Evaluation of Activated Carbon Micropowder Composite Additive in Asphalt Mixtures This test case is used to verify the VOCs emission reduction effect, high temperature stability and anti-photo-oxidative aging performance of the activated carbon micro powder composite additives prepared in Examples 1 to 9 under hot-mix asphalt mixture conditions.
[0060] 1. Sample preparation and addition method The asphalt mixture is mixed using an external admixture method.
[0061] Benchmark group (blank control): using conventional 70# base asphalt and graded aggregate.
[0062] Experimental groups 1 to 9 (median additive groups): While maintaining the aggregate gradation and asphalt-aggregate ratio, composite additive particles prepared in Examples 1 to 9 were introduced during hot mixing at 165°C. The amount added was controlled at 0.30% of the total mass of the asphalt mixture, with the total mass of the asphalt mixture as 100%.
[0063] Experimental group 1-L (lower limit addition group): The composite additive prepared in application example 1 was used, and its mixing amount was controlled at 0.15%.
[0064] Experimental group 1-H (upper limit addition group): The composite additive prepared in application example 1 was used, and its mixing amount was controlled at 0.45%.
[0065] 2. Test Methods and Performance Indicators VOCs (BTEX and low-molecular-weight PAHs) emission reduction rate test: The escaping gases collected in a closed system under mixing conditions (160°C) were quantitatively analyzed by gas chromatography-mass spectrometry (GC-MS). The percentage reduction in the total release of characteristic organic compounds (BTEX and low-molecular-weight PAHs) of each experimental group relative to the baseline group was calculated.
[0066] Long-term resistance to photo-oxidative aging (residual penetration ratio): The cured asphalt specimens of each group were placed in an ultraviolet aging chamber and subjected to simulated long-term service under strong ultraviolet radiation and alternating heat aging. The penetration before and after aging was tested, and the residual penetration ratio was calculated (the higher the value, the stronger the additive's ability to resist photo-oxidative aging and extend road service life).
[0067] Dynamic stability (cycles / mm): The dynamic stability of asphalt mixture under high temperature conditions of 60°C is determined by rutting test according to standard method to characterize the pavement's ability to resist high temperature rutting deformation.
[0068] 3. Test Result Comparison Table The data obtained after standardized testing of each group of samples are shown in Table 1 below: Table 1 Table 1 shows that the asphalt mixtures in each experimental group exhibited different technical effects in terms of volatile organic compound (VOC) emission reduction, resistance to photo-oxidative aging, and high-temperature stability. Experimental groups 1 to 4, by introducing activated carbon micropowder modified by co-thermolysis of a eutectic solvent precursor and transition metal salt, and through the synergistic effect of layered silicates, hindered amine light stabilizers, antioxidants, and surface compatibility modifiers, optimized the overall road performance and emission reduction efficiency of the materials. The heteroatoms and anchored metal centers in the microstructure of the modified activated carbon micropowder chemically adsorb and lock in the emitted characteristic organic compounds, while the tortuous path constructed by the layered silicate sheets slowed down the diffusion rate of gas molecules, increasing the capture probability.
[0069] Compared to the groups mentioned above, experimental group 5, due to the use of unmodified ordinary activated carbon powder, lacks specific modified active sites and mainly relies on weak physical adsorption, resulting in a significant reduction in its emission reduction efficiency. Experimental group 6, lacking the physical barrier effect of layered silicates, allows volatile gases to easily diffuse and escape, thus weakening its emission reduction effect.
[0070] Regarding anti-aging and high-temperature stability, experimental group 7, lacking heterocyclic units capable of capturing photo-oxidative aging free radicals, experienced matrix molecule degradation after long-term radiation, resulting in a significant decline in residual penetration ratio. Experimental group 8, lacking a composite antioxidant system, was unable to inhibit thermo-oxidative aging chains and decompose hydrogen peroxide during thermal processing, leading to severe thermal damage to the matrix and deterioration in high-temperature resistance to rutting deformation. Experimental group 9, lacking a surface compatibility modifier, experienced secondary aggregation of inorganic powders, reducing the effective specific surface area and causing a decline in adsorption efficiency and mechanical stability. These findings demonstrate that the combination of these technical features creates a significant synergistic effect.
[0071] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included within the scope of the technical solution of the present invention.
Claims
1. A composite additive for activated carbon micro powder, characterized in that, By mass percentage, it includes the following components: Composite modified activated carbon micro powder: 65%-75%; Layered silicates: 12%-18%; Hindered amine light stabilizers: 4%-8%; Antioxidant: 3%-7%; Surface compatibility modifier: 1%-3%; The composite modified activated carbon micro powder is obtained by modifying the activated carbon micro powder matrix by co-pyrolysis of a eutectic solvent precursor and a transition metal salt under an inert atmosphere. The eutectic solvent precursor is formed by the condensation of anhydrous choline chloride and a nitrogen-containing hydrogen bond donor, wherein the nitrogen-containing hydrogen bond donor is selected from urea and / or thiourea. In preparing the composite modified activated carbon micro powder, the mass ratio of the activated carbon micro powder matrix, the nitrogen-containing hydrogen bond donor, and the transition metal salt is 100:100-130:3-6, wherein the transition metal salt is anhydrous cuprous chloride or anhydrous ferric chloride.
2. The activated carbon micro powder composite additive according to claim 1, characterized in that, The layered silicate is at least one of montmorillonite, layered kaolinite, and lithium diatomite.
3. The activated carbon micro powder composite additive according to claim 1, characterized in that, The hindered amine light stabilizer is a polymeric hindered amine light stabilizer with a thermal weight loss of ≤5% at 200℃.
4. The activated carbon micro powder composite additive according to claim 1, characterized in that, The antioxidant is a composite antioxidant system consisting of a primary antioxidant and an auxiliary antioxidant. The primary antioxidant contains stereohindered phenols; the secondary antioxidant is a trivalent phosphorus phosphite compound; the mass ratio of the primary antioxidant to the secondary antioxidant is 1:1.5-2.
5.
5. The activated carbon micro powder composite additive according to claim 1, characterized in that, The surface compatibility modifier is a titanate coupling agent and / or a stearic acid derivative.
6. The activated carbon micro powder composite additive according to claim 1, characterized in that, The composite modified activated carbon micro powder is prepared by the following steps: S1 mixes anhydrous choline chloride with a nitrogen-containing hydrogen bond donor and performs a condensation reaction to obtain a eutectic solvent precursor; then a transition metal salt is added to perform a complexation reaction. S2, mix the product after the reaction in step S1 with the activated carbon micro powder matrix, dry, and obtain carbon powder precursor. S3, the carbon powder precursor is placed in an inert atmosphere and subjected to co-pyrolysis modification at 550-650℃.
7. The activated carbon micron powder composite additive according to claim 6, characterized in that, In step S1, the temperature of both the condensation reaction and the complexation reaction is 90-110℃, and the time of the complexation reaction is 0.5-1.5h. In step S2, the activated carbon micro powder matrix is pre-dispersed in anhydrous ethanol and ultrasonically dispersed; After the reaction in step S3 is completed, the resulting product is washed until neutral and dried.
8. The method for preparing the activated carbon micron powder composite additive according to any one of claims 1-7, characterized in that, Includes the following steps: S1: Mix the composite modified activated carbon micro powder and the layered silicate; Then, the surface compatibility modifier is introduced and stirred and premixed to form an oleophilic transition layer on the powder surface; The mixture S2: Add the hindered amine light stabilizer and the antioxidant to the mixture obtained in step S1, and heat to 115-125°C for thermal blending to obtain the agglomeration precursor; S3: The agglomeration precursor obtained in step S2 is fed into a molding machine and granulated at 120-130℃, then cooled and crushed to obtain the activated carbon micro powder composite additive.
9. The preparation method according to claim 8, characterized in that, In step S1, the stirring and premixing speed is 1500-2000 rpm; In step S3, the particle size of the activated carbon micro powder composite additive is controlled to be 0.1-0.5 mm.
10. The application of the activated carbon micro powder composite additive according to any one of claims 1-7 in the preparation of asphalt, wherein the amount of activated carbon micro powder composite additive incorporated is 0.15%-0.45% based on 100% of the mass of the asphalt mixture.