A method for the preparation of modified anthracene oil for carbon black production

Abstract

This application provides a method for preparing modified anthracene oil for carbon black production, comprising the following steps: Step S1: Introducing ozone into the anthracene oil for ultrasonic emulsification to obtain an emulsion mixture, wherein: ultrasonic frequency: 20–40 kHz; ultrasonic power density: 0.5–0.8 W / cm³ 2 Ultrasonic working time: 1–1.5 h; bubble residence time: 10–15 s; bubble diameter: 50–100 μm; O3 / anthracene oil gas-liquid volume ratio: 0.1–0.3:1; Step S2: The emulsified mixture is alternately subjected to mechanical stirring and ultrasonic emulsification, wherein: ultrasonic frequency: 40–70 kHz; ultrasonic power density: 0.8–1.2 W / cm³ 2 O3 / anthracene oil gas-liquid volume ratio: 0.3–0.5:1; bubble diameter: <30 μm; total working time for mechanical stirring and ultrasonic emulsification: 1.5–2 h. Step S3: Dehydration to obtain modified anthracene oil. The modified anthracene oil obtained in this application has good compositional uniformity, is not prone to stratification, and has few by-products, thus meeting the requirements for raw materials in the production of high-quality carbon black.

Description

Technical Field

[0001] This application relates to the field of anthracene oil deep processing, and in particular to a method for preparing modified anthracene oil for carbon black production. Background Technology

[0002] Carbon black is a major reinforcing agent in the rubber industry. Through physical adsorption and chemical bonding, it can enhance the mechanical properties of rubber, improve abrasion resistance (such as tire tread), tensile strength, and tear resistance, and improve processing flowability and vulcanization characteristics. Carbon black accounts for 30% to 50% of rubber compounding agents and is widely used in tires, seals, rubber hoses, and other products.

[0003] Anthracene oil, as a traditional raw material for carbon black production, directly affects the structure (DBP oil absorption value), particle size distribution, surface activity, and impurity content of carbon black, which in turn determines the reinforcing properties, abrasion resistance, and processing fluidity of rubber products.

[0004] Anthracene oil is a byproduct of coal tar fractionation. Its composition is complex, primarily consisting of polycyclic aromatic hydrocarbons (anthracene, phenanthrene, carbazole, etc.), aliphatic hydrocarbons, and small amounts of sulfur / nitrogen-containing heterocyclic compounds. Due to differences in component polarity and density, as well as environmental temperature, anthracene oil can stratify during storage and transportation. In carbon black production, anthracene oil is spray-dried and pyrolyzed at high temperatures. After stratification, the sprayed anthracene oil exhibits uneven composition. Components with denser aromatic rings form a highly branched, porous carbon black structure after pyrolysis, exhibiting higher structure but lower density. Components lacking aromatic rings or with sparse aromatic rings form a carbon black structure with small-molecule free radicals, exhibiting lower structure but higher density. This results in uneven quality of the prepared carbon black. Summary of the Invention

[0005] In view of this, this application proposes a method for preparing modified anthracene oil for carbon black production, which makes it difficult for the components of the anthracene oil to separate during storage and transportation.

[0006] A method for preparing modified anthracene oil for carbon black production includes the following steps:

[0007] Step S1: Ozone is introduced into anthracene oil for ultrasonic emulsification to obtain an emulsion mixture, wherein:

[0008] Ultrasonic frequency: 20–40 kHz;

[0009] Ultrasonic power density: 0.5~0.8 W / cm³ 2 ;

[0010] Ultrasonic working time: 1–1.5 hours;

[0011] Bubble residence time: 10–15 seconds;

[0012] Bubble diameter: 50–100 μm;

[0013] O3 / anthracene oil gas-liquid volume ratio: 0.1~0.3:1;

[0014] Step S2: The emulsified mixture is alternately subjected to mechanical stirring and ultrasonic emulsification, wherein:

[0015] Ultrasonic frequency: 40–70 kHz;

[0016] Ultrasonic power density: 0.8~1.2W / cm³ 2 ;

[0017] O3 / anthracene oil gas-liquid volume ratio: 0.3~0.5:1;

[0018] Bubble diameter: <30μm;

[0019] Total working time for mechanical stirring and ultrasonic emulsification: 1.5 to 2 hours.

[0020] Step S3: Remove water to obtain modified anthracene oil.

[0021] The technical advantages of this application are as follows: This application utilizes ozone to oxidize anthracene oil, and through staged emulsification combined with mechanical stirring, the modified anthracene oil obtained has good component uniformity, is not prone to stratification, and has few by-products, which can meet the requirements of raw materials for high-quality carbon black production. Detailed Implementation

[0022] The embodiments of the technical solution of this application will be described in detail below. The following embodiments are only used to illustrate the technical solution of this application more clearly, and are therefore only examples, and should not be used to limit the scope of protection of this application.

[0023] This application utilizes ozone to oxidize anthracene oil to a certain extent, increasing the content of polar functional groups in the anthracene oil. Verification has shown that increasing the content of polar functional groups can reduce phase separation caused by polar repulsion between different components. Furthermore, the introduction of functional groups increases molecular polarity, leading to more uniform density among the components and weakening the driving force of stratification caused by gravitational sedimentation. In addition, polar functional groups can adsorb onto the surface of aromatic crystals, hindering the orderly arrangement of molecules and inhibiting anthracene crystallization, thereby reducing the risk of solid-liquid stratification at low temperatures.

[0024] However, when anthracene oil is over-oxidized, several problems arise in experiments. First, with increasing oxidation, the viscosity of the anthracene oil increases dramatically, even gelling, making it impossible to prepare carbon black via spray droplets. Second, the carboxylic acid content in the anthracene oil increases significantly, enhancing its corrosiveness. Furthermore, over-oxidation leads to greater differences in molecular structure. Some molecules are completely oxidized into small-molecule acids, while others remain as original aromatic hydrocarbons, causing a re-stratification due to density differences, contradicting the initial goal of mitigating stratification.

[0025] Therefore, this application requires strict control over the oxidation degree of anthracene oil. At the same time, it is also necessary to improve oxidation uniformity and avoid localized over-oxidation or under-oxidation.

[0026] The initial approach adopted in this application was to introduce ozone into the anthracene oil for one-step emulsification. However, during the experiment, regardless of the parameter adjustments, the problem of uneven oxidation of the anthracene oil could not be resolved, leading to localized over-oxidation of the anthracene oil. The anthracene oil separated into layers within 48 hours.

[0027] Through repeated experiments, this application demonstrates that secondary emulsification combined with stirring can significantly improve the stability of anthracene oil, as shown in the following scheme:

[0028] The method for preparing modified anthracene oil for carbon black production includes the following steps:

[0029] Step S1: Ozone is introduced into anthracene oil for ultrasonic emulsification to obtain an emulsion mixture, wherein:

[0030] Ultrasonic frequency: 20-40 kHz; This application uses low-frequency ultrasound, which has a stronger cavitation effect and can effectively break up the initial large bubbles, avoiding excessive dissipation of high-frequency ultrasonic energy.

[0031] Ultrasonic power density: 0.5~0.8 W / cm³ 2 This application avoids excessive cavitation leading to localized high temperatures by using low power density, thus protecting the polycyclic aromatic hydrocarbon structure in anthracene oil from damage.

[0032] Ultrasonic working time: 1 to 1.5 hours; within this working time, the anthracene oil undergoes mild oxidation, avoiding excessive local oxidation of the anthracene oil during the subsequent ultrasonic emulsification and mechanical stirring process.

[0033] The bubble residence time is 10-15 seconds. According to the experiment, based on the viscosity of anthracene oil, if the bubble residence time is too short, the gas-liquid mass transfer is insufficient and the oxidation reaction occurs less; if the bubble residence time is too long, the bubbles are prone to aggregate and float to the surface.

[0034] Bubble diameter: 50-100 μm; bubbles of this size are suspended in anthracene oil and settle slowly, thus balancing dispersibility and mass transfer efficiency.

[0035] O3 / anthracene oil gas-liquid volume ratio: 0.1~0.3:1; ozone demand is low in the mild oxidation stage. Too high a gas-liquid ratio can easily lead to local over-oxidation, while too low a ratio will result in insufficient oxidation.

[0036] Step S2: The emulsified mixture is alternately subjected to mechanical stirring and ultrasonic emulsification, wherein:

[0037] Ultrasonic frequency: 40–70 kHz; through high-frequency ultrasound, stronger shearing force can be generated, further breaking the 50–100 μm bubbles in S1 to the submicron level.

[0038] Ultrasonic power density: 0.8~1.2W / cm³ 2 The higher power density compensates for the energy attenuation of high-frequency ultrasound, ensuring the efficiency of bubble refinement, while also preventing catalyst deactivation after subsequent addition.

[0039] O3 / anthracene oil gas-liquid volume ratio: 0.3-0.5:1; secondary emulsification requires further oxidation of anthracene oil to increase ozone supply. The gas-liquid ratio of 0.3-0.5 matches the bubble refinement ability of S2, which can prevent excessive ozone from escaping.

[0040] Bubble diameter: <30μm; As the degree of oxidation increases, the viscosity of anthracene oil gradually increases, and submicron-sized bubbles can penetrate the viscous phase of anthracene oil, shortening the ozone diffusion distance.

[0041] Mechanical stirring speed: 300-500 rpm;

[0042] Total working time for mechanical stirring and ultrasonic emulsification: 1.5 to 2 hours.

[0043] Mechanical stirring prevents bubble agglomeration, while ultrasonic emulsification refines the bubbles; alternating these processes improves the uniformity of oxidation.

[0044] Step S3: Remove water to obtain modified anthracene oil.

[0045] In a preferred embodiment, in step S1, ozone is introduced into the anthracene oil through a porous distributor, and the initial ozone bubble diameter is 1-5 mm.

[0046] In a preferred embodiment, in step S1, an intermittent ultrasonic mode is used, with ultrasonic operation for 5 minutes followed by a 2-minute pause, and this cycle is repeated to avoid continuous cavitation leading to local overheating and excessive ozone decomposition.

[0047] In a preferred embodiment, in step S2, the contact time between anthracene oil and ozone is increased by adjusting the circulation flow rate, with the circulation flow rate being 1 to 1.5 times the volume / h.

[0048] Specifically, in step S1, the emulsified mixture enters a static mixer. The static mixer has built-in spiral blades or corrugated plates. Through the division-rotation-merging motion of the fluid in the narrow flow channel, strong shear force is generated to further break up the bubbles in the emulsified mixture. Then, the emulsified mixture in the static mixer is pumped into an ultrasonic reactor for further breaking up through a circulating pump. After that, the ultrasonically broken mixture is pumped back into the static mixer, and the cycle continues.

[0049] In a preferred embodiment, the anthracene oil temperature is 30–50°C. At this temperature, the solubility of ozone in the anthracene oil remains at 0.05–0.1 mol / L, avoiding increased mass transfer resistance due to increased viscosity at low temperatures or a sudden drop in solubility at high temperatures. Furthermore, when a MnO2 / activated carbon supported catalyst is subsequently added, the catalyst activity is higher within this temperature range.

[0050] In a preferred embodiment, anthracene oil is premixed with the catalyst, followed by ultrasonic emulsification of ozone and anthracene oil. Premixing, such as through mechanical stirring or ultrasonic dispersion, allows the catalyst to form a stable suspension in the anthracene oil, preventing agglomeration that would occur with direct addition.

[0051] In a preferred embodiment, the catalyst is a supported catalyst.

[0052] In a preferred embodiment, the support is activated carbon. The adsorption properties of the activated carbon support can enrich ozone, thereby locally increasing the ozone concentration on the catalyst surface and accelerating the hydroxylation reaction rate.

[0053] In a preferred embodiment, the catalyst is MnO2.

[0054] In a preferred embodiment, the catalyst concentration is 0.01–0.05 mol / L.

[0055] The solution of this application will be described in detail below with reference to specific embodiments.

[0056] Example 1

[0057] The ultrasonic frequency is 30 kHz, and the power density is 0.6 W / cm². 2 Intermittent mode (ultrasound for 5 min - stop for 2 min), working time 1.2 h; ozone is introduced into anthracene oil through a porous distributor, gas-liquid ratio 0.2, bubble diameter 70-90 μm, residence time 12 s; anthracene oil temperature 40℃, premixed catalyst (MnO2 / activated carbon, concentration 0.03 mol / L).

[0058] The resulting emulsified mixture was then subjected to secondary emulsification and stirring: ultrasonic frequency 50 kHz, power density 1.0 W / cm², mechanical stirring (300 rpm) and ultrasonic emulsification were alternated (30 min each cycle); emulsified mixture flow rate 1.5 m / s, circulation flow rate 1.2 times volume / h, gas-liquid ratio 0.4, bubble diameter 20-25 μm; total working time 2 h.

[0059] Vacuum dehydration was performed at a vacuum degree of -0.07 MPa, a temperature of 50°C, and a time of 1 hour, reducing the moisture content to 0.3% to obtain modified anthracene oil.

[0060] Comparative Example 1

[0061] No graded emulsification is used: only S1 ultrasonic emulsification is retained, without S2 alternating treatment, and the process directly proceeds to the dehydration step.

[0062] Comparative Example 2

[0063] No catalyst: No MnO2 / activated carbon catalyst is added, and the remaining steps are the same as in Example 1.

[0064] Comparative Example 3

[0065] Temperature runaway: The temperature of S1 / S2 is controlled at 60℃ (exceeding the range of 30-50℃), and the remaining steps are the same as in Example 1.

[0066] Comparative Example 4

[0067] Continuous ultrasound: S1 uses continuous ultrasound (without interruption mode) for 1.2 hours. The remaining steps are the same as in Example 1.

[0068] Comparative Example 5

[0069] No circulation flow rate adjustment: S2 circulation flow rate is 0.3 times the volume / h (less than 1 to 1.5 times), and the remaining steps are the same as in Example 1.

[0070] The modified anthracene oil and corresponding carbon black products of Example 1 and each comparative example were subjected to performance tests, and the results are shown in Table 1:

[0071]

[0072] Compared with Comparative Example 1: Example 1:

[0073] Example 1 showed an acid value of 13.5 mg KOH / g, indicating that the modified anthracene oil underwent mild oxidation, meeting the requirements for raw material polarity in carbon black production. The acid value deviation was only ±2.1%, demonstrating excellent uniformity of the oxidation reaction. Furthermore, the modified anthracene oil in Example 1 exhibited a stratification time of 152 hours, indicating excellent stability.

[0074] Comparative Example 1 had an acid value of only 8.2 mg KOH / g, with a deviation of ±8.5%. Due to the lack of S2 static shear and circulation, the bubble size was uneven, the ozone concentration in some areas was too low, and the oxidation was incomplete and the uniformity was poor.

[0075] This demonstrates that Example 1, through graded emulsification combined with mechanical stirring, can significantly improve the oxidation uniformity of anthracene oil and significantly improve its stability, resulting in modified anthracene oil that is less prone to stratification.

[0076] Compared with Comparative Examples 2 and 3, Example 1:

[0077] Example 1 shows that the anthraquinone content is only 0.8%, indicating that there are few byproducts generated by the oxidation of anthraquinone oil. This is because the MnO2 / activated carbon catalyst selectively catalyzes the hydroxylation reaction, and the temperature of 40°C inhibits non-selective oxidation.

[0078] The anthraquinone content in Comparative Example 2 increased to 1.5%, indicating that due to the lack of a catalyst for directional action, ozone easily induces anthraquinone oxidation and ring-opening, leading to excessive oxidation.

[0079] Comparative Example 3 (high temperature 60℃): the anthraquinone content reached 2.3%, indicating that high temperature accelerates the decomposition of ozone into ·O free radicals, leading to excessive oxidation.

[0080] This demonstrates that the synergistic effect of the catalyst and temperature in Example 1 can inhibit the excessive oxidation of anthracene oil.

[0081] Compared with Comparative Examples 4 and 5, Example 1:

[0082] Example 1: Intermittent ultrasound can avoid local overheating, and the circulation flow can prolong the ozone contact time, thereby improving oxidation uniformity.

[0083] In Comparative Example 4, continuous cavitation led to excessively high local temperatures, deactivation of catalyst active sites, and an increase in acid value fluctuation to ±4.8%.

[0084] Comparative Example 5 showed insufficient ozone residence time, an acid value of only 10.1 mg KOH / g, underdeveloped carbon black structure, and a DBP absorbance of 108 cm⁻¹. 3 / 100g.

[0085] This demonstrates that Example 1 can guarantee process stability.

[0086] Compared with the carbon black prepared in Examples 1-5: Example 1:

[0087] Example 1: The oil absorption value of the carbon black was 128 cm⁻¹. 3 / 100g and DBP absorption value (135 cm) 3The carbon black structure ( / 100g) was significantly higher than that of the control group, indicating that the carbon black structure was more developed and the primary aggregates were more complex. This was due to the modified anthracene oil polar functional groups, such as hydroxyl and carboxyl groups, which promoted cross-linking between carbon black particles.

[0088] Particle size distribution: The particle size distribution range of Example 1 is 1.8, which is smaller than that of the comparative example of 2.0 to 2.5. This is because the anthracene oil with uniform oxidation is more uniformly cracked in the carbon black reactor, avoiding local coking or particle size fluctuations.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for preparing modified anthracene oil for carbon black production, characterized in that: Includes the following steps: Step S1: Ozone is introduced into anthracene oil for ultrasonic emulsification to obtain an emulsion mixture. The process uses intermittent ultrasonic mode, wherein: Ultrasonic frequency: 20–40 kHz; Ultrasonic power density: 0.5~0.8 W / cm³ 2 ; Ultrasonic working time: 1–1.5 hours; Bubble residence time: 10–15 seconds; Bubble diameter: 50–100 μm; O3 / anthracene oil gas-liquid volume ratio: 0.1~0.3:1; Step S2: The emulsified mixture is alternately subjected to mechanical stirring and ultrasonic emulsification, and the contact time between anthracene oil and ozone is increased by adjusting the circulation flow rate, wherein: Ultrasonic frequency: 40–70 kHz; Ultrasonic power density: 0.8~1.2W / cm³ 2 ; O3 / anthracene oil gas-liquid volume ratio: 0.3~0.5:1; Bubble diameter: <30μm; Total working time for mechanical stirring and ultrasonic emulsification: 1.5–2 hours; The circulation flow rate is 1 to 1.5 times the volume per hour; Step S3: Remove water to obtain modified anthracene oil; The anthracene oil temperature in steps S1 and S2 is 30–50°C.

2. The method for preparing modified anthracene oil for carbon black production as described in claim 1, characterized in that: In step S1, the intermittent ultrasound mode specifically means: ultrasound operation for 5 minutes, followed by a 2-minute pause.

3. The method for preparing modified anthracene oil for carbon black production as described in claim 1, characterized in that: In step S1, anthracene oil is premixed with the catalyst, and then ozone is ultrasonically emulsified with the anthracene oil.

4. The method for preparing modified anthracene oil for carbon black production as described in claim 3, characterized in that: The catalyst is a supported catalyst.

5. The method for preparing modified anthracene oil for carbon black production as described in claim 4, characterized in that: The load is activated carbon.

6. The method for preparing modified anthracene oil for carbon black production as described in claim 4, characterized in that: The catalyst is MnO2.

7. The method for preparing modified anthracene oil for carbon black production as described in claim 6, characterized in that: The catalyst concentration is 0.01–0.05 mol / L.

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