CN117210033A - Thermal cracking carbon black and preparation method thereof - Google Patents

Abstract

Thermal cracking carbon black is prepared by the preparation method of the (c), in particular, a process for preparing a thermally cracked carbon black having a low ash content and a high specific surface area, which comprises: (1) providing a thermally cracked carbon black particle; (2) Preparing an alkali metal carbonate saturated solution, and soaking the carbon black in the step (1) into the saturated solution; removing water from the saturated solution to obtain carbon black deposited with alkali metal carbonate; (3) Immersing the carbon black deposited with the alkali metal carbonate into acid liquor, and carrying out ultrasonic treatment; (4) followed by filtration, washing and drying to obtain carbon black particles. The ash content is greatly reduced by the combination of a large amount of carbon dioxide generated by the reaction of alkali metal carbonate deposited on carbon black and acid and ultrasonic treatment, and the specific surface area is improved.

Description

A kind of thermal cracking carbon black and its preparation method

Technical field

The present invention relates to a thermal cracking carbon black and a preparation method thereof, in particular to a thermal cracking carbon black with low ash content and high specific surface area and a preparation method thereof.

technical background

Since its birth, tires have played an important role in the field of science and technology, especially in the field of transportation. At present, the number of scrap tires in the world is huge, with annual output reaching 1.5 billion and continuing to grow. Tires are mainly composed of rubber, carbon black, skeleton materials and additives. The high-temperature pyrolysis of waste tires can decompose pyrolysis oil, pyrolysis carbon black, pyrolysis gas and other substances. Among them, pyrolysis oil and pyrolysis gas can be effectively utilized. For example, pyrolysis oil has a high calorific value, making it a substitute for traditional liquid fuels; pyrolysis gas (such as hydrogen) can be burned directly to provide industrial production. Provides energy; pyrolytic carbon black is more difficult to process. The main chemical components of waste tire pyrolysis carbon black are carbon, oxygen, copper, zinc, silicon, etc., and its ash content is relatively high. In addition, thermal cracking carbon black also deposits some tar produced during the thermal cracking process. Compared with ordinary carbon black, thermal cracking carbon black has obvious differences in chemical properties due to impurities such as ash and tar. Its reinforcing effect on rubber is poor and cannot meet the needs of applications.

The prior art discloses some technical means for removing impurities such as ash. CN110964350A describes a thermal cracking carbon black deliming process, which includes the following steps: mixing thermal cracking carbon black, acid solution, dispersant, and complexing agent, reacting, solid-liquid separation, obtaining filter residue and filtrate, cleaning the filter residue, and granulating A finished carbon black product is obtained; the ash content of the carbon black is reduced from 18.1wt% to about 5wt%. CN102504619A records a waste tire cracking carbon black purification process, which includes acid-washing and alkali-washing carbon black and then undergoing an acid-washing process; the ash content of the carbon black produced is about 2.6wt%. However, this impurity removal effect is still not enough, and the ash content is still relatively high, so it cannot be used alone as reinforcing carbon black for rubber materials.

Therefore, the existing technology still exists to further reduce the ash and other impurities in the thermal cracking carbon black of waste tires to obtain thermal cracking carbon black with low ash content and high specific surface area.

Contents of the invention

The technical problem solved by this application is to provide a thermal cracking carbon black with low ash content and high specific surface area, which has properties close to those of commercial carbon black.

The invention provides a method for preparing thermal cracking carbon black, which includes the following steps:

(1) Provide a thermal cracking carbon black particle;

(2) Prepare a saturated alkali metal carbonate solution, and soak the carbon black in step (1) into the above saturated solution; remove the water in the saturated solution to obtain carbon black deposited with alkali metal carbonate;

(3) The carbon black deposited with alkali metal carbonate is treated with acid under ultrasound;

(4) Then filter, wash and dry to obtain carbon black particles.

Wherein, the thermal cracking carbon black particles are produced by thermal cracking of waste tires, and then crushed, and a magnetic device is used to remove iron filings. The thermal cracking methods used can be: direct thermal cracking, molten salt thermal cracking, co-thermal cracking, plasma thermal cracking, etc. For example, waste tires with steel wires and fibers removed are broken into small pieces, washed and dried, and then placed in a thermal cracking furnace for thermal cracking. The final temperature of thermal cracking is 350-700℃, for example, 400℃, 450℃, 500℃, 550℃, 600℃, 650℃, etc., and the heating rate is 5-30℃/min, for example, 5℃/min, 10℃ /min, 15℃/min, 20℃/min, 25℃/min, 30℃/min, etc. The final temperature maintenance time is 10-120min. The obtained carbon black is then ground evenly, and a magnetic device is used to remove iron filings to obtain thermal cracking carbon black.

Wherein, the alkali metal carbonate in step (2) is one or more of sodium bicarbonate, sodium carbonate, potassium bicarbonate and potassium carbonate, preferably a combination of sodium bicarbonate and potassium carbonate. When preparing a mixed solution of sodium bicarbonate and potassium carbonate, first prepare saturated solutions of sodium bicarbonate and potassium carbonate respectively, and then mix them according to a certain volume ratio. The ratio of the two can be any ratio, preferably 1:5-5:1, for example, 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4 :1, 5:1, etc.; the temperature for preparing the saturated alkali metal carbonate solution is 20-90°C, preferably 50-80°C. The solid-liquid ratio of the carbon black particles and the alkali metal carbonate saturated solution in step (1) is 1:0.1-4 (g/mL), preferably 1:0.5-2.5 (g/mL), so that the carbon black particles are partially or Completely immersed in a saturated solution of alkali metal carbonates. At this time, the carbon black surface can be fully infiltrated into the alkali metal carbonate saturated solution through stirring, turning, vibration, etc. The soaking time is 2-48 hours, preferably 12-36 hours, for example, 12 hours, 16 hours, 20 hours, 24 hours, 28 hours, 32 hours, 36 hours, etc.

Wherein, the acid solution in step (3) is a common inorganic acid in this field, such as one or more of hydrochloric acid, nitric acid, sulfuric acid and hydrofluoric acid; in step (3), the concentration of the acid is 1-30 mol /L, the ultrasonic treatment time is 0.5-50 hours, preferably 4-24 hours, and the treatment temperature is: 50-90°C. The molar ratio of alkali metal carbonate and acid is 1:4-40, preferably 1:8-20.

Preferably, step (5) is performed after step (4). Step (5) is to add the carbon black particles of step (4) into the acid solution and perform ultrasonic treatment; followed by filtration, washing and drying. The acid solution in step (5) is a common inorganic acid in the art, such as one or more of hydrochloric acid, nitric acid, sulfuric acid and hydrofluoric acid. In step (5), the concentration of the acid is 1-30 mol/L, the solid-liquid ratio of the carbon black particles and the acid is 1:5-30 (g/mL), and the ultrasonic treatment time is 0.5-50 hours, preferably 4- 24 hours, treatment temperature: 50-90℃.

Preferably, sulfuric acid or hydrochloric acid is used for treatment in step (3), and hydrofluoric acid is used for treatment in step (5).

Optionally, the method for preparing carbon black obtained by thermal cracking of waste tires of the present invention also includes the step of using a strong alkali to treat the carbon black particles. Strong bases can be sodium hydroxide, potassium hydroxide, etc.

The invention discloses a method for preparing carbon black obtained by thermal cracking of waste tires. This method significantly reduces the ash content and increases the specific surface area. This method first deposits alkali metal carbonate on the outer surface of carbon black and the surface of inner pores. Then it is immersed in the acid solution. The alkali metal carbonate reacts with the acid to produce a large amount of carbon dioxide gas. With the action of ultrasound, the ash on the carbon black, including the ash in the inner pores, can be separated from the surface of the carbon black and fully react with the acid for conversion. is a soluble salt. During this process, organic substances such as tar deposited on the carbon black will also be partially detached. In addition, a subsequent second acid treatment and optional alkali treatment can further reduce the ash and organic matter content.

Detailed ways

The present invention is further described below in conjunction with the examples, which are intended to help readers better understand the technical solutions of the present invention, and do not limit the implementation scope of the technical solutions of the present invention in any way.

Preparation example

The waste tires with the steel wires and fibers removed are broken into small pieces with a diameter of 1.5cm, washed and dried, and then placed in a thermal cracking furnace for thermal cracking. The thermal cracking conditions are: nitrogen atmosphere, initial temperature is 80°C, final thermal cracking temperature is 500°C, heating rate is 10°C/min, and final thermal cracking temperature maintenance time is 50 min. The obtained carbon black is then ground evenly, and iron filings are removed using a magnetic device. Finally, thermal cracking carbon black A is obtained.

Example 1

Weigh 100g of the thermally cracked carbon black A obtained in the preparation example; prepare a saturated sodium carbonate solution at 80°C, and soak the thermally cracked carbon black A in the saturated sodium carbonate solution at 80°C for 24 hours. The solid-liquid ratio of the saturated solution is 1:1.5 (g/mL); heat to remove the water in the saturated solution to obtain carbon black with sodium carbonate deposited; put the carbon black with sodium carbonate deposited into 5 mol/L sulfuric acid and conduct ultrasonic treatment For 5 hours, the molar ratio of alkali metal carbonate and acid was 1:16; then filtered, washed three times with water at 50°C, and vacuum dried to obtain carbon black particles.

Example 2

Refer to the preparation method of Example 1, the difference from Example 1 is that a saturated solution of sodium bicarbonate is used instead of a saturated solution of sodium carbonate.

Example 3

Refer to the preparation method of Example 1, the difference from Example 1 is that a saturated solution of potassium bicarbonate is used instead of a saturated solution of sodium carbonate.

Example 4

Refer to the preparation method of Example 1, the difference from Example 1 is that a saturated solution of potassium carbonate is used instead of a saturated solution of sodium carbonate.

Example 5

Referring to the preparation method of Example 1, the difference from Example 1 is that: prepare saturated solutions of sodium bicarbonate and potassium carbonate at 80°C, and mix the two solutions with a volume ratio of 1:1 to form an alkali metal carbonate. Saturated solution, replace the saturated solution of sodium carbonate.

Example 6

Referring to the preparation method of Example 1, the difference from Example 1 is that: prepare saturated solutions of sodium bicarbonate and potassium carbonate at 80°C, and mix the two solutions with a volume ratio of 2:1 to form an alkali metal carbonate. Saturated solution, replace the saturated solution of sodium carbonate.

Example 7

Referring to the preparation method of Example 1, the difference from Example 1 is that: prepare saturated solutions of sodium bicarbonate and potassium carbonate at 80°C respectively, and mix the two solutions with a volume ratio of 1:2 to form an alkali metal carbonate. Saturated solution, replace the saturated solution of sodium carbonate.

Example 8

Refer to the preparation method of Example 7, the difference from Example 7 is that 7 mol/L hydrochloric acid is used instead of sulfuric acid.

Example 9

Refer to the preparation method of Example 7, the difference from Example 7 is that 7 mol/L nitric acid is used instead of sulfuric acid.

Example 10

Refer to the preparation method of Example 7, the difference from Example 7 is that 5 mol/L hydrofluoric acid is used instead of sulfuric acid.

Example 11

Refer to the preparation method of Example 7. The difference from Example 7 is that after the first acid treatment and filtering, washing and drying, a second acid treatment is performed, using 5 mol/L hydrofluoric acid, carbon black particles and acid The solid-liquid ratio is 1:10 (g/mL). Specifically, the dried carbon black was added to hydrofluoric acid, treated with ultrasonic for 5 hours, then filtered, washed three times with water at 50°C, and vacuum dried to obtain carbon black particles.

Example 12

Refer to the preparation method of Example 8. The difference from Example 8 is that after the first pickling and filtering, washing and drying, a second acid treatment is performed, using 5 mol/L hydrofluoric acid, carbon black particles and acid The solid-liquid ratio is 1:10 (g/mL). Specifically, the dried carbon black was added to hydrofluoric acid, treated with ultrasonic for 5 hours, then filtered, washed three times with water at 50°C, and vacuum dried to obtain carbon black particles.

Comparative example 1

Weigh 100g of the thermally cracked carbon black A obtained in the preparation example; prepare a saturated sodium carbonate solution at 80°C, soak the thermally cracked carbon black A in the saturated sodium carbonate solution at 80°C, and sonicate for 5 hours. The thermally cracked carbon black A and The solid-to-liquid ratio of the saturated sodium carbonate solution is 1:5 (g/mL); it is then filtered, washed three times with water at 50°C, and dried under vacuum; the obtained carbon black is put into 5 mol/L sulfuric acid and sonicated for 5 hours. ; Then filter, wash three times with water at 50°C, and dry under vacuum to obtain carbon black particles.

Comparative example 2

Weigh 100g of the thermally cracked carbon black A obtained in the preparation example; prepare a 10 mol/L sodium hydroxide solution at 80°C, and soak the thermally cracked carbon black A in the saturated sodium hydroxide solution at 80°C and sonicate for 5 hours. The solid-liquid ratio of thermal cracking carbon black A and saturated sodium hydroxide solution is 1:5 (g/mL); then filter, wash with water 3 times at 50°C, and dry in vacuum; put the obtained carbon black into 5 mol/L in sulfuric acid and sonicated for 5 hours; then filtered, washed three times with water at 50°C, and dried under vacuum to obtain carbon black particles.

Comparative example 3

Weigh 100g of the thermally cracked carbon black A obtained in the preparation example; put the obtained carbon black into 5 mol/L sulfuric acid and conduct ultrasonic treatment for 5 hours; then filter, wash with water 3 times at 50°C, and dry in vacuum; at 80°C Prepare a saturated solution of sodium hydroxide, soak the thermally cracked carbon black A in a 10mol/L sodium hydroxide solution at 80°C, and sonicate for 5 hours. The solid-liquid ratio of the thermally cracked carbon black A and the saturated sodium hydroxide solution is: 1:5 (g/mL); then filtered, washed three times with water at 50°C, and dried under vacuum to obtain carbon black particles.

The ash content and specific surface area of the carbon black particles prepared in the preparation examples, Examples 1-12 and Comparative Examples 1-3 were measured according to national standards:

1) Ash content: Tested according to the operating procedures of GB/T 3780.10-2017;

2) Specific surface area: Tested according to the operating procedures of GB/T 3780.5-2017.

Specific measurement results are listed in Table 1.

Table 1

Examples 1-12 adopt the preparation method of the present application, wherein Examples 1-4 adopt a single alkali metal carbonate, Examples 5-10 adopt a combination of sodium bicarbonate and potassium carbonate, and Examples 11 and 12 additionally use Second acid treatment. The main difference between Comparative Example 1 and Example 1 is that the carbon black alkali metal carbonate saturated solution is sonicated, followed by filtration, washing and drying; instead of depositing the alkali metal carbonate on the carbon black. The main difference between Comparative Example 2 and Example 1 is that an alkali metal carbonate solution is not used for ultrasonic treatment of carbon black, but sodium hydroxide commonly used in the prior art is used for alkali washing treatment of carbon black. Comparative Example 3 is based on Comparative Example 2 and exchanges the order of acid treatment and alkali treatment. It can be seen from the data in Table 1 that the ash content and specific surface area of the carbon black prepared in Examples 1-12, especially Examples 5-10, and more especially Examples 11-12, using the preparation method of the present application are significantly Better than Comparative Examples 1-3 and Preparation Examples. The alkali metal carbonate in Comparative Example 1 did not deposit on the surface of carbon black and subsequently react with acid, and its effect was poor, even inferior to Comparative Examples 2 and 3 using sodium hydroxide. It can be seen that it is very critical to deposit alkali metal carbonate on the surface of carbon black and then react with acid. In addition, according to Examples 1-7, it can be seen that different alkali metal carbonates have different effects, and the combination of sodium bicarbonate and potassium carbonate has a better effect. Furthermore, secondary acid treatment can further reduce the ash content and increase the specific surface area.

Claims (10)

1. A method for preparing thermally cracked carbon black, comprising the following steps: (1) Provide a thermal cracking carbon black particle; (2) Prepare a saturated alkali metal carbonate solution, and soak the carbon black in step (1) into the above saturated solution; remove the water in the saturated solution to obtain carbon black deposited with alkali metal carbonate; (3) Dip the carbon black deposited with alkali metal carbonate into the acid solution and conduct ultrasonic treatment; (4) Then filter, wash and dry to obtain carbon black particles. 2. A method for preparing tire thermal cracking carbon black according to claim 1, characterized in that the temperature for preparing the saturated alkali metal carbonate solution in step (2) is 20-90°C. 3. A method for preparing tire thermal cracking carbon black according to claim 1, characterized in that: the alkali metal carbonate in step (2) is sodium bicarbonate, sodium carbonate, potassium bicarbonate and potassium carbonate. one or more of them. 4. A method for preparing tire thermal cracking carbon black according to claim 1, characterized in that: the alkali metal carbonate in step (2) is a combination of sodium bicarbonate and potassium carbonate. 5. A method for preparing tire thermal cracking carbon black according to claim 1, characterized in that: the acid liquid in step (3) is one or more of hydrochloric acid, nitric acid, sulfuric acid and hydrofluoric acid. . 6. A method for preparing tire thermal cracking carbon black according to claim 1, characterized in that: the ultrasonic treatment time in step (3) is 0.5-50 hours. 7. A method for preparing tire thermal cracking carbon black according to claim 1, characterized in that: step (5) is also performed after step (4), specifically: adding carbon black particles to the acid solution again and Sonicate; followed by filtration, washing and drying. 8. A method for preparing tire thermal cracking carbon black according to claim 7, characterized in that: the acid liquid in step (5) is one or more of hydrochloric acid, nitric acid, sulfuric acid and hydrofluoric acid. . 9. A method for preparing tire thermal cracking carbon black according to claim 7, characterized in that: the acid liquid in step (3) is sulfuric acid or hydrochloric acid, and the acid liquid in step (5) is Hydrofluoric acid. 10. A thermal cracking carbon black prepared according to the preparation method of any one of claims 1 to 9.