A eutectic solvent-based de-polymerized asphalt regenerant and a preparation method thereof

Abstract

This invention belongs to the field of asphalt recycling agent technology, specifically relating to a DES-based targeted depolymerization asphalt recycling agent and its preparation method. It solves the problem of weak depolymerization ability of traditional bio-based recycling agents in aged asphalt. The agent comprises a mixture of stearic acid, naphthenic oil, and DES. The DES mixture consists of choline chloride-ethylene glycol-based DES and choline chloride-propylene glycol-based DES. The preparation method of the DES mixture includes: Step 1: Mixing choline chloride-ethylene glycol-based DES and choline chloride-propylene glycol-based DES; Step 2: Placing the mixed choline chloride-ethylene glycol-based DES and choline chloride-propylene glycol-based DES in a glass bottle and placing it on a magnetic stirrer; Step 3: Stirring until a colorless and transparent liquid is formed, obtaining the DES mixture; Step 4: Placing the naphthenic oil in a glass bottle equipped with a rotor, adding the stearic acid and DES mixture, and stirring until the solid particles are completely dissolved. This invention exhibits strong hydrogen bonding, while the asphaltene and resinous micelles in aged asphalt exhibit weak hydrogen bonding.

Description

Technical Field

[0001] This invention belongs to the field of aged asphalt recycling, specifically relating to a DES-based regenerator with high efficiency in depolymerization and its preparation method. Background Technology

[0002] Existing regenerators mainly include: 1. Mineral-based regenerators (such as aromatic hydrocarbon oils, naphthenic oils, waste engine oils, etc.), which have the advantages of being homologous to asphalt, having good compatibility, strong regeneration capacity, and mature technology. They mainly rely on replenishing the missing aromatic and saturated light components in aged asphalt, reducing the viscosity and hardness of asphalt through physical dilution and dissolution; 2. Bio-based regenerators, such as vegetable oils, waste edible oils, lignin-pyrolyzed oils, etc. In addition to replenishing light components, they can also interact with the polar aggregates of asphaltene produced during aging through their own polarity, depolymerizing them, thereby more effectively restoring the fluidity of asphalt. They have the advantages of being renewable, low-toxicity, environmentally friendly, and having significant effects on restoring low-temperature crack resistance and fatigue resistance. 3. Reactive regenerators, such as compounds containing active functional groups like epoxy groups, are commonly used in the regeneration of SBS-modified asphalt. These regenerators not only replenish lightweight components but also chemically react with degradation products (such as hydroxyl and carboxyl groups) of SBS polymers (or asphaltenes) in aged asphalt, re-crosslinking or reconnecting broken molecular chains. This fundamentally repairs the polymer structure and significantly restores key properties of modified asphalt, such as viscoelasticity and elastic recovery. However, they are relatively expensive and have complex formulations, primarily targeting modified asphalt.

[0003] Existing asphalt recycling agents are mainly divided into mineral oil-based (such as naphthenic oil) and bio-based types. While naphthenic oil can effectively replenish the light components missing in aged asphalt and restore its penetration and ductility, its main component is saturated hydrocarbons, which have limited compatibility with the highly polar asphaltenes in aged asphalt. This leads to the easy volatilization of light components during long-term thermo-oxidative aging of the recycled asphalt, insufficient improvement in anti-aging performance, and susceptibility to secondary aging. Traditional surfactants (such as stearic acid), although able to improve wetting and dispersibility, have weak ability to harmonize the chemical components of aged asphalt, resulting in poor performance when used alone. Furthermore, existing recycling agents generally lack the ability to effectively depolymerize asphaltenes in aged asphalt, making it difficult to simultaneously achieve low-temperature crack resistance and high-temperature rutting resistance in the recycled asphalt. Summary of the Invention

[0004] This invention provides a eutectic solvent (DES)-based depolymerizing asphalt regenerator and its preparation method, which solves the problem of weak depolymerization ability of traditional bio-based regenerators in aged asphalt. It depolymerizes the colloidal structure of aged asphalt from a gel-type to a sol-type structure. Simultaneously, naphthenic oil can supplement light oil components and disperse the depolymerized asphalt. Stearic acid, as an amphiphilic material, acts as a linker between non-polar substances and polar DES in aged asphalt. This comprehensively changes the colloidal structure of aged asphalt and effectively improves the low-temperature performance of recycled asphalt.

[0005] A eutectic solvent (DES)-based depolymerized bitumen regenerator comprising stearic acid and naphthenic oil, comprising a DES mixture;

[0006] Furthermore, the DES mixture consists of choline chloride-ethylene glycol DES and choline chloride-propylene glycol DES.

[0007] The eutectic solvent (DES)-based depolymerized bitumen regenerator of the present invention is prepared according to the following steps:

[0008] Step 1: Calculate by mass percentage and mix 16.7% choline chloride-ethylene glycol DES and 83.3% choline chloride-propylene glycol DES.

[0009] Step 2: Place the mixed choline chloride-ethylene glycol DES and choline chloride-propylene glycol DES in a glass bottle and place it on a magnetic stirrer;

[0010] Step 3: Stir at 80-90℃ and 650-850r / min until a colorless and transparent liquid is formed to obtain the DES mixture;

[0011] Step 4: According to the mass percentage, put 84%-88% of the naphthenic oil into a glass bottle equipped with a rotor, add 2% stearic acid and 10%-14% of the DES mixture, and stir at 80-90℃ and 650-850r / min until the solid particles are completely dissolved to obtain the eutectic solvent (DES) based depolymerized asphalt regenerator.

[0012] Furthermore, in step one, the weight ratio of choline chloride to ethylene glycol in the choline chloride-ethylene glycol DES is 1:0.98.

[0013] Furthermore, in step one, the weight ratio of choline chloride to propylene glycol in the choline chloride-propylene glycol DES is 1:1.14.

[0014] Furthermore, the molar ratio of choline chloride to ethylene glycol in choline chloride-ethylene glycol DES is 1:2.

[0015] Furthermore, in step one, the molar ratio of choline chloride to propylene glycol in the choline chloride-propylene glycol DES is 1:2.

[0016] The beneficial effect of this invention lies in the strong hydrogen bonding of the DES mixture, while the asphaltenes and resinous micelles in aged asphalt exhibit weak hydrogen bonding. - Stacking effect. Based on the principle that strong bonds can break weak bonds, DES-based composite regenerators can efficiently depolymerize large-sized asphaltenes and gum micelles in aged asphalt. Simultaneously, stearic acid, as an amphiphilic substance, can establish a connection between the highly polar DES and the asphaltenes and gum micelles. Naphthenic oil acts as a buffer, preventing the DES mixture from directly contacting the high-temperature environment. It also acts as a dispersant, dispersing the depolymerized asphaltenes micelles within the naphthenic oil, thus altering the asphalt colloidal structure. The long-chain structure of stearic acid can also intercalate between the depolymerized asphaltenes, thereby achieving targeted depolymerization and regeneration of aged asphalt. Detailed Implementation Detailed Implementation Method 1

[0018] A depolymerized bitumen rejuvenator based on eutectic solvent (DES) comprises the following raw materials by weight percentage: 10% DES mixture, 2% stearic acid, and 88% naphthenic oil (rejuvenator) [naphthenic oil type KN4006]. 6g of the rejuvenator is added to 100g of aged base bitumen. Detailed Implementation Method 2

[0020] The difference between this embodiment and the previous embodiment is that a eutectic solvent (DES)-based depolymerized asphalt rejuvenator comprises the following raw materials by weight percentage: 12% DES mixture, 2% stearic acid, and 86% naphthenic oil. 6g of the rejuvenator is added to 100g of aged base asphalt. Detailed Implementation Method 3

[0022] The difference between this embodiment and the previous embodiment is that a eutectic solvent (DES)-based depolymerized asphalt rejuvenator comprises the following raw materials by weight percentage: 14% DES mixture, 2% stearic acid, and 84% naphthenic oil. 6g of the rejuvenator is added to 100g of aged base asphalt. Detailed Implementation Method 4

[0024] The difference between this embodiment and the previous embodiment is that a eutectic solvent (DES)-based depolymerized asphalt rejuvenator comprises the following raw materials by weight percentage: 10% DES mixture, 2% stearic acid, and 88% naphthenic oil. 6g of the rejuvenator is added to 100g of aged SBS modified asphalt. Detailed Implementation Method 5

[0026] The difference between this embodiment and the previous embodiment is that a eutectic solvent (DES)-based depolymerized asphalt rejuvenator comprises the following raw materials by weight percentage: 12% DES mixture, 2% stearic acid, and 86% naphthenic oil. 6g of the rejuvenator is added to 100g of aged SBS modified asphalt. Detailed Implementation Method 6

[0028] The difference between this embodiment and the previous embodiment is that a eutectic solvent (DES)-based depolymerized asphalt regenerator, by weight percentage, comprises the following raw materials: 14% DES mixture, 2% stearic acid, and 84% naphthenic oil. 6g of the regenerator is added to 100g of aged SBS modified asphalt.

[0029] Comparative Example 1 is 90# matrix aged asphalt aged in a rotating thin film oven for 170 min.

[0030] Comparative Example 2 is ID-type SBS modified aged asphalt aged in a rotating thin-film oven for 170 min.

[0031] Comparative Example 3 is unaged 90# base asphalt.

[0032] Comparative Example 4 is a stearic acid-naphthenic oil-based recycled asphalt prepared by adding 2% stearic acid and 4% naphthenic oil by weight of asphalt to 90# matrix aged asphalt.

[0033] Performance testing

[0034] 1. Penetration, ductility, and softening point tests

[0035] 90# base asphalt and ID-type SBS modified asphalt were aged in a rotating thin-film oven for 170 min to obtain aged asphalt. At 160℃, 6% by weight of DES-based targeted depolymerization asphalt rejuvenator was added to both the 90# base aged asphalt and the ID-type SBS modified aged asphalt, and stirred for 15 min to ensure uniform dispersion of the rejuvenator in the aged asphalt, thus obtaining recycled asphalt. Penetration, softening point, and ductility tests were performed on the 90# base aged asphalt, the ID-type SBS modified aged asphalt, and the recycled asphalt. Examples 1-3 were 90# base recycled asphalt, and Examples 4-6 were ID-type SBS modified recycled asphalt. According to the specification "Technical Specification for Construction of Highway Asphalt Pavement" (JTG F40—2004), the ductility test temperature for Examples 1-3 and Comparative Example 1 was 15℃, and the ductility test temperature for Examples 4-6 and Comparative Example 2 was 5℃. The test results are shown in Table 1.

[0036] Table 1. Test results of penetration, ductility, and softening point.

[0037]

[0038] In Table 1, compared with Comparative Examples 1 and 2, the ductility of Examples 1-3 and Examples 4-6 all increased, indicating that the regenerator with targeted depolymerization function can significantly restore the low-temperature performance of aged asphalt.

[0039] 2. Gel permeation chromatography test

[0040] 90# base asphalt was aged in a rotary thin-film oven for 170 minutes to obtain aged asphalt. Then, 6% (by weight) of DES-based composite rejuvenator and 6% (by weight) of stearic acid-naphthenic oil composite rejuvenator were added to the aged asphalt at 160℃ and stirred for 15 minutes to ensure uniform dispersion of the rejuvenators, resulting in recycled asphalt. Comparative Example 1 shows the aged asphalt obtained by aging 90# base asphalt in a rotary thin-film oven for 170 minutes. Comparative Example 3 shows 90# base asphalt. Comparative Example 4 shows the recycled asphalt prepared by adding 2% (by weight) of stearic acid and 4% (by weight) of naphthenic oil to 90# base aged asphalt.

[0041] The difference between Comparative Example 1 and Examples 1-3 is that Comparative Example 1 uses 90# matrix aged asphalt.

[0042] The difference between Comparative Example 3 and Examples 1-3 is that Comparative Example 3 uses 90# base asphalt.

[0043] The difference between Comparative Example 4 and Examples 1-3 is that the regenerant in Comparative Example 4 does not contain the DES mixture.

[0044] Gel permeation chromatography was used to analyze the molecular weights of 90# base asphalt, aged 90# base asphalt, DES recycled asphalt, and naphthenic oil recycled asphalt. Aging resulted in an increase in the number, size, and molecular weight of asphaltenes in the 90# base asphalt. If the molecular weight of the DES-based recycled asphalt was close to that of the 90# base asphalt, and the molecular weight of the naphthenic oil-based recycled asphalt was close to that of the aged 90# base asphalt, it proves that the DES-based regenerator has a targeted depolymerization effect on asphaltenes, while the naphthenic oil-based regenerator does not. Detailed test results are shown in Table 2.

[0045] Table 2 Results of Gel Permeation Chromatography

[0046]

[0047] In the data in Table 2, M W (g / mol) represents the weight-average molecular weight, which reflects the molecular weight of asphaltenes and resins in asphalt. N (g / mol) is the number-average molecular weight, which reflects the molecular weight of the asphalt-saturated phenols and aromatic components. Compared with Comparative Example 3, Comparative Example 4 and Examples 1-3, M N and M W The values ​​of (high molecular weight) all decreased, M N M represents the molecular weight of aromatics and saturated phenols in asphalt. W Represents the molecular weight of asphaltenes and resins in asphalt. When M N and M WThe decrease indicates that the regenerator with targeted depolymerization function has a depolymerization effect on the micelles that have aggregated in aged asphalt due to aging, thus reducing the molecular weight.

[0048] Compared to Comparative Example 4, M in Example 1 N and M W The decrease was not significant because the DES weight ratio in the regenerator with targeted depolymerization function in Example 1 was only 10%, and the DES content was low, so the depolymerization effect was not obvious.

[0049] Compared to Comparative Example 4, M in Examples 2 and 3 N and M W Both decreased significantly, demonstrating excellent depolymerization performance. However, compared to Example 2, M in Example 3 decreased significantly. W There has been an increase. In the regenerator with targeted depolymerization function in Example 3, the weight ratio of DES was 14%, while in the regenerator with targeted depolymerization function in Example 2, the weight ratio of DES was 12%. This indicates that excessive DES will cause the depolymerized asphaltenes and gum micelles to crosslink again under the action of hydrogen bonds, leading to M W rise.

[0050] The present invention relates to a depolymerizing asphalt regenerator based on eutectic solvent (DES) and its preparation method. By introducing eutectic solvent (DES) as a functional carrier and utilizing its strong hydrogen bond network, it works synergistically with stearic acid to significantly disintegrate asphaltenes aggregated in aged asphalt due to hydrogen bonds and polar forces, achieving "depolymerization-solubilization" at the microstructural level. On the other hand, naphthenic oil is used as a buffer medium to encapsulate the DES dispersed in the naphthenic oil, preventing the DES from being destroyed at high temperatures. Furthermore, by utilizing the amphiphilic properties of stearic acid, the highly polar DES and the less polar naphthenic oil are combined to form a composite regenerator, constructing a "polar-nonpolar" gradient compatibility system. Finally, the depolymerized asphaltenes can be dispersed in the naphthenic oil, achieving the goal of targeted depolymerization and efficient regeneration.

[0051] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

[0052] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A eutectic solvent-based depolymerized bitumen regenerator, comprising stearic acid and naphthenic oil, characterized in that... It also contains a DES mixture.

2. The eutectic solvent-based depolymerizing bitumen regenerator according to claim 1, characterized in that... The DES mixture consists of choline chloride-ethylene glycol DES and choline chloride-propylene glycol DES.

3. The preparation method of a eutectic solvent-based depolymerized asphalt regenerator as described in claim 1, characterized in that... The preparation method of the eutectic solvent-based depolymerized asphalt regenerator is carried out according to the following steps: Step 1: Calculated by mass percentage, a mixture of 16.7% choline chloride-ethylene glycol DES and 83.3% choline chloride-propylene glycol DES is prepared. Step 2: Place the mixed choline chloride-ethylene glycol DES and choline chloride-propylene glycol DES in a glass bottle and place it on a magnetic stirrer; Step 3: Stir at 80-90℃ and 650-850r / min until a colorless and transparent liquid is formed to obtain the DES mixture; Step 4: According to the mass percentage, put 84%-88% of the naphthenic oil into a glass bottle equipped with a rotor, add 2% of stearic acid and 10%-14% of DES mixture, and stir at 80-90℃ and 650-850r / min until the solid particles are completely dissolved to obtain the eutectic solvent-based depolymerized asphalt regenerator.

4. The preparation method of a eutectic solvent-based depolymerized asphalt regenerator according to claim 3, characterized in that... In step one, the weight ratio of choline chloride to ethylene glycol in the choline chloride-ethylene glycol DES is 1:0.

98.

5. The preparation method of a eutectic solvent-based depolymerized asphalt regenerator according to claim 3, characterized in that... In the choline chloride-propylene glycol-based DES in step one, the weight ratio of choline chloride to propylene glycol is 1:1.

14.

6. The method for preparing a eutectic solvent-based depolymerized asphalt regenerator according to claim 3, characterized in that... The molar ratio of choline chloride to ethylene glycol in the choline chloride-ethylene glycol-based DES is 1:2.

2.

7. The preparation method of a eutectic solvent-based depolymerized asphalt regenerator according to claim 3, characterized in that... In step one, the molar ratio of choline chloride to propylene glycol in the choline chloride-propylene glycol DES is 1:2.09.

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