Method for preparing residual oil derived activated carbon through two-step pyrolysis method and application of residual oil derived activated carbon

Abstract

The invention discloses a method for preparing residual oil derived activated carbon through a two-step pyrolysis method and application thereof, and relates to the technical field of activated carbon preparation, and the method comprises the following steps: selection and pretreatment of a residual oil raw material, primary pyrolysis and carbonization treatment of the residual oil raw material, secondary pyrolysis and activation treatment of the residual oil raw material, and post-treatment of an activated carbon semi-finished product. The residual oil raw material is subjected to dehydration, crushing screening and desulfurization pretreatment before pyrolysis, impurities in the residual oil raw material can be effectively removed, the particle size is adjusted, the subsequent pyrolysis treatment effect is improved, the pyrolysis activation efficiency of a primary carbide can be effectively improved through combination of a physical activation method and a chemical activation method, and the pyrolysis efficiency of the residual oil raw material is improved. The residual oil derived activated carbon prepared by the two-step pyrolysis method based on primary pyrolysis carbonization and secondary pyrolysis activation can more effectively control the pore structure and the specific surface area of the activated carbon, so that the adsorption performance, the pressure resistance and the wear resistance of the residual oil derived activated carbon are improved.

Description

Technical Field

[0001] The invention relates to the technical field of activated carbon preparation, and in particular to a method for preparing residual oil-derived activated carbon by a double-step pyrolysis method and application thereof. Background Art

[0002] Activated carbon is a specially treated carbon material with a highly developed internal pore structure. These pores give the activated carbon a large specific surface area. This structure enables the activated carbon to effectively adsorb impurity molecules in gases, liquids or colloidal solids, thereby playing a purification role. Activated carbon can be made from a variety of carbon-containing materials, such as wood, coconut shells, coal, bamboo, etc., through high-temperature carbonization and activation processes. Activated carbon plays an important role in many fields due to its unique physical and chemical properties. It is one of the indispensable materials in modern life.

[0003] Residue oil, also known as heavy oil or residual oil, is the heavy residue in the petroleum refining process. In the crude oil distillation process, lighter components such as gasoline and diesel are distilled out first, and the remaining heavy part forms residue oil, which is a viscous black liquid with a high carbon content and a low hydrogen content, and usually contains more impurities such as sulfur, nitrogen and metals. Since residue oil contains more impurities and heavy components, direct combustion will bring about environmental pollution and equipment corrosion. Therefore, the treatment and conversion technology of residue oil is very important. Through proper treatment and conversion technology of residue oil, its value can be maximized while reducing the impact on the environment.

[0004] Using residual oil as raw material, activated carbon can be prepared after a series of chemical or physical treatments, namely, residual oil-derived activated carbon. This type of activated carbon has a high specific surface area and a developed pore structure, and can effectively adsorb impurities in various gases and liquids. It has broad application prospects. The preparation of residual oil-derived activated carbon can not only effectively utilize the by-products in the petroleum refining process, but also provide efficient solutions for environmental protection and energy storage.

[0005] Most of the existing methods for preparing residual oil-derived activated carbon have complicated processes. The residual oil raw material cannot be effectively pretreated before pyrolysis, which affects the subsequent pyrolysis effect, and cannot be fully and efficiently activated during the pyrolysis process, which affects the quality and yield of the final activated carbon product. In addition, the adsorption performance of the prepared activated carbon needs to be improved. At the same time, the mechanical strength is not high, and it does not have good wear resistance and pressure resistance, which seriously limits its application scope and is not convenient for wide promotion and application. Therefore, the present invention proposes a method for preparing residual oil-derived activated carbon by a double-step pyrolysis method and its application to solve the problems existing in the prior art. Summary of the invention

[0006] In view of the above problems, the purpose of the present invention is to propose a method for preparing residual oil-derived activated carbon by a double-step pyrolysis method and its application, which solves the problem that the adsorption performance of the activated carbon prepared by the existing residual oil-derived activated carbon preparation method needs to be improved, and the mechanical strength is not high, and it does not have good wear resistance and pressure resistance, which seriously limits its application scope.

[0007] In order to achieve the purpose of the present invention, the present invention is implemented by the following technical scheme: a method for preparing residual oil-derived activated carbon by a double-step pyrolysis method, comprising the following steps: Step 1: Select the residual oil produced in the petroleum refining process as the raw material, and perform dehydration, crushing, screening and desulfurization pretreatment on the selected residual oil raw material in sequence to obtain a relatively clean residual oil raw material; Step 2: placing the pretreated residual oil raw material into a carbonization device, heating it in an inert gas to cause a pyrolysis reaction of the residual oil raw material, completing the primary pyrolysis treatment, forming gaseous products and liquid products for recycling, and the solid residue formed is the preliminary carbonized product; Step 3: Mix the carbon dioxide with the preliminary carbonized product, and perform preliminary heating activation at a temperature of 700 to 1000° C., and then perform secondary heating deactivation on the preliminary carbonized product after the preliminary heating activation treatment by a chemical activation method to form an activated carbon semi-finished product; Step 4: placing the activated carbon semi-finished product in an inert atmosphere and cooling it to room temperature, then washing the activated carbon semi-finished product with deionized water, and drying it after washing to obtain a residual oil-derived activated carbon finished product.

[0008] A further improvement is that in step 1, the specific steps of dehydrating the residual oil raw material are: firstly placing the residual oil raw material in a centrifuge for centrifugal treatment, using centrifugal force to initially separate the water from the residual oil raw material, and then placing the residual oil raw material in a vacuum environment and heating it until the water evaporates.

[0009] A further improvement is that in the step 1, the specific steps of crushing and screening the dehydrated residual oil raw material for pretreatment are: first, the residual oil raw material after dehydration pretreatment is added to a crusher for crushing treatment, and the crushed material obtained after the crushing treatment is added to a screening machine for screening, and the particle size of the residual oil raw material that passes the screening is controlled to be 85-125 mesh.

[0010] A further improvement is that in step one, the specific steps of desulfurization pretreatment of the residual oil raw material after crushing and screening pretreatment are: hydrogen is introduced into the residual oil raw material to react the sulfide therein with the hydrogen to generate hydrogen sulfide, and then the hydrogen sulfide is separated from the residual oil raw material to complete the desulfurization pretreatment.

[0011] A further improvement is that in the step 2, the residual oil raw material is heated in nitrogen or argon at a heating rate of 10-15°C / min, and the heating is stopped when the temperature reaches 400-600°C and kept warm for 60-75 minutes.

[0012] A further improvement is that in step three, the specific steps of using the chemical activation method to perform secondary heating deactivation on the preliminary carbonized product are as follows: first, the preliminary carbonized product that has been initially heated and activated is mixed with an activator, and stirred and immersed in a heating environment of 80 to 90°C for 12 to 16 hours, and then the immersed mixture is placed in an activation equipment and maintained at an activation temperature of 600 to 800°C for 60 to 75 minutes.

[0013] A further improvement is that the mixing mass ratio of the preliminary carbonized product to the activator is 1:1, and the activator is selected from one of phosphoric acid and potassium hydroxide.

[0014] A further improvement is that in the step 4, the activated carbon semi-finished product is placed in nitrogen or carbon dioxide for cooling, the resistivity of the deionized water is higher than 18 MΩ·cm, the activated carbon semi-finished product is completely immersed in deionized water and washed repeatedly three times, and after washing, the activated carbon semi-finished product is placed in a drying oven at a temperature of 100 to 150°C for drying.

[0015] The invention discloses an application of residual oil-derived activated carbon prepared by a double-step pyrolysis method, wherein the residual oil-derived activated carbon is used as an electrode material in a supercapacitor.

[0016] The beneficial effects of the present invention are as follows: by dehydrating, crushing, screening and desulfurizing the residual oil raw material before pyrolysis, the present invention can effectively remove impurities therein, adjust the particle size, and improve the effect of subsequent pyrolysis treatment; and by combining the physical activation method with the chemical activation method, the pyrolysis activation efficiency of the preliminary carbonized material can be effectively improved, the yield and quality of activated carbon can be improved, and the waste of raw materials can be reduced; at the same time, the residual oil-derived activated carbon prepared by the double-step pyrolysis method based on the primary pyrolysis carbonization and the secondary pyrolysis activation can more effectively control the pore structure and specific surface area of ​​the activated carbon, thereby improving its adsorption performance, pressure resistance and wear resistance, and preparing an activated carbon product with better performance, making it more suitable for specific application requirements and convenient for wide promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0018] Figure 1 The present invention is a schematic flow chart of a method for preparing residual oil-derived activated carbon by a double-step pyrolysis method. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example

[0020] See also Figure 1 This embodiment provides a method for preparing residual oil-derived activated carbon by a two-step pyrolysis method, comprising the following steps: Step 1: Selection and pretreatment of residual oil raw materials Select the residual oil produced in the process of petroleum refining as the raw material, first put the residual oil raw material into a centrifuge for centrifugal treatment, use centrifugal force to initially separate the water from the residual oil raw material, then place the residual oil raw material in a vacuum environment and heat it until the water evaporates, complete the dehydration treatment, and obtain a fully dehydrated residual oil raw material to avoid the presence of water affecting the subsequent carbonization and activation process, thereby ensuring the quality of the activated carbon product; Subsequently, the dehydrated residual oil raw material is added to a crusher for crushing, and the crushed material obtained after the crushing is added to a screening machine for screening. The residual oil raw material that fails the screening is further crushed, and the particles of the residual oil raw material that passes the screening are controlled to be 85 meshes. By screening out a suitable particle size range, the pyrolysis efficiency is improved, so as to facilitate the subsequent heat treatment work; Then, hydrogen is introduced into the crushed and screened residual oil raw material, so that the sulfide therein reacts with the hydrogen to generate hydrogen sulfide, and then the hydrogen sulfide is separated from the residual oil raw material to complete the desulfurization pretreatment, which can reduce the pollution of the environment and the corrosion of the equipment by the sulfide in the subsequent heat treatment process, is more environmentally friendly, and reduces equipment loss; This embodiment can effectively remove moisture from the residual oil raw material, remove impurities therein, and adjust the particle size through the above-mentioned pretreatment process, thereby improving the effect of subsequent pyrolysis treatment and the quality of the final activated carbon; Step 2: Primary pyrolysis and carbonization of residual oil raw materials The residual oil raw material pretreated in step 1 is placed in a carbonization device, and nitrogen is introduced into the carbonization device, and the residual oil raw material is heated to 400°C at a heating rate of 10°C / min in nitrogen, and kept warm for 60 minutes, so that the residual oil raw material undergoes a pyrolysis reaction, the residual oil particles are fully carbonized, and the primary pyrolysis treatment is completed. During the primary pyrolysis process of the residual oil raw material, the macromolecular organic matter in the residual oil raw material is decomposed under inert gas conditions (i.e., a low-oxygen environment), and the gaseous products such as hydrogen, methane and carbon dioxide and the liquid products such as aromatic compounds, alcohols and ketones formed after the primary pyrolysis treatment are recycled, and the solid residue formed is the preliminary carbonized product; Step 3: Secondary pyrolysis and activation of residual oil raw materials The carbon dioxide is mixed with the preliminary carbonized product obtained in step 2, and preliminary heating activation is performed under a heating environment of 700°C to achieve pore opening of the preliminary carbonized product and increase the specific surface area, and then the preliminary carbonized product subjected to preliminary heating activation is mixed with phosphoric acid in a mass ratio of 1:1, and stirred and impregnated for 12 hours under a heating environment of 80°C to ensure that the phosphoric acid is evenly distributed in the preliminary carbonized product, and then the impregnated mixture is placed in an activation device, and maintained at an activation temperature of 600°C for 60 minutes to allow the preliminary carbonized product to chemically react with the activator to form a large number of micropores and mesopores, thereby increasing the specific surface area of ​​the activated carbon, completing secondary heating decomposition activation, and forming an activated carbon semi-finished product with a porous structure after activation; Step 4: Post-processing of semi-finished activated carbon The activated carbon semi-finished product after activation in step 3 is placed in nitrogen and cooled to room temperature to avoid reaction with oxygen. After the activated carbon semi-finished product is cooled, the surface of the activated carbon semi-finished product is restored to stability, and then the activated carbon semi-finished product is washed with deionized water with a resistivity higher than 18 MΩ·cm. During the washing, the activated carbon semi-finished product is completely immersed in deionized water and washed repeatedly three times to remove the residual activator and ash on the activated carbon semi-finished product. After washing, it is placed in a drying oven at a temperature of 100° C. for drying to completely remove the moisture introduced during the washing process. After the drying treatment is completed, the residual oil-derived activated carbon finished product is obtained.

[0021] The residual oil-derived activated carbon prepared in this embodiment is used as an electrode material in a supercapacitor. Its working principle is based on the electric double-layer capacitance (EDLC) mechanism. At the electrode / electrolyte interface, ions in the electrolyte will aggregate under the action of the electric field to form a double layer to store charges. The high specific surface area of ​​the residual oil-derived activated carbon provides a large number of charge storage sites, thereby improving the energy storage capacity of the supercapacitor. Example

[0022] See also Figure 1This embodiment provides a method for preparing residual oil-derived activated carbon by a two-step pyrolysis method, comprising the following steps: Step 1: Selection and pretreatment of residual oil raw materials Select the residual oil produced in the process of petroleum refining as the raw material, first put the residual oil raw material into a centrifuge for centrifugal treatment, use centrifugal force to initially separate the water from the residual oil raw material, then place the residual oil raw material in a vacuum environment and heat it until the water evaporates, complete the dehydration treatment, and obtain a fully dehydrated residual oil raw material to avoid the presence of water affecting the subsequent carbonization and activation process, thereby ensuring the quality of the activated carbon product; Subsequently, the dehydrated residual oil raw material is added to a crusher for crushing, and the crushed material obtained after the crushing is added to a screening machine for screening. The residual oil raw material that fails the screening is further crushed, and the particles of the residual oil raw material that passes the screening are controlled to be 125 meshes. By screening out a suitable particle size range, the pyrolysis efficiency is improved, so as to facilitate the subsequent heat treatment work; Then, hydrogen is introduced into the crushed and screened residual oil raw material, so that the sulfide therein reacts with the hydrogen to generate hydrogen sulfide, and then the hydrogen sulfide is separated from the residual oil raw material to complete the desulfurization pretreatment, which can reduce the pollution of the environment and the corrosion of the equipment by the sulfide in the subsequent heat treatment process, is more environmentally friendly, and reduces equipment loss; This embodiment can effectively remove moisture from the residual oil raw material, remove impurities therein, and adjust the particle size through the above-mentioned pretreatment process, thereby improving the effect of subsequent pyrolysis treatment and the quality of the final activated carbon; Step 2: Primary pyrolysis and carbonization of residual oil raw materials The residual oil raw material pretreated in step 1 is placed in a carbonization device, and nitrogen or argon is introduced into the carbonization device, and the residual oil raw material is heated to 600° C. at a heating rate of 15° C. / min in nitrogen or argon, and kept warm for 75 minutes, so that the residual oil raw material undergoes a pyrolysis reaction, and the residual oil particles are fully carbonized to complete the primary pyrolysis treatment. During the primary pyrolysis process of the residual oil raw material, the macromolecular organic matter in the residual oil raw material is decomposed under inert gas conditions (i.e., a low-oxygen environment), and the gaseous products such as hydrogen, methane and carbon dioxide and the liquid products such as aromatic compounds, alcohols and ketones formed after the primary pyrolysis treatment are recycled, and the solid residue formed is the preliminary carbonized product; Step 3: Secondary pyrolysis and activation of residual oil raw materials The carbon dioxide is mixed with the preliminary carbonized product obtained in step 2, and preliminary heating activation is performed under a heating environment of 1000°C to realize the opening of the preliminary carbonized product and increase the specific surface area, and then the preliminary carbonized product subjected to preliminary heating activation is mixed with potassium hydroxide in a mass ratio of 1:1, and stirred and impregnated for 16 hours under a heating environment of 90°C to ensure that the potassium hydroxide is evenly distributed in the preliminary carbonized product, and then the impregnated mixture is placed in an activation device, and maintained at an activation temperature of 800°C for 75 minutes to allow the preliminary carbonized product to chemically react with the activator to form a large number of micropores and mesopores, thereby increasing the specific surface area of ​​the activated carbon, completing secondary heating deactivation, and forming an activated carbon semi-finished product with a porous structure after activation; Step 4: Post-processing of semi-finished activated carbon The activated carbon semi-finished product after activation in step 3 is placed in carbon dioxide and cooled to room temperature to avoid reaction with oxygen. After the activated carbon semi-finished product is cooled, the surface of the activated carbon semi-finished product is restored to stability, and then the activated carbon semi-finished product is washed with deionized water with a resistivity higher than 18 MΩ·cm. During washing, the activated carbon semi-finished product is completely immersed in deionized water and washed repeatedly three times to remove the residual activator and ash on the activated carbon semi-finished product. After washing, it is placed in a drying oven at a temperature of 150° C. for drying to completely remove the moisture introduced during the washing process. After the drying process is completed, the residual oil-derived activated carbon product is obtained.

[0023] The residual oil-derived activated carbon prepared in this embodiment is used as an electrode material in a supercapacitor. Its working principle is based on the electric double-layer capacitance (EDLC) mechanism. At the electrode / electrolyte interface, ions in the electrolyte will aggregate under the action of the electric field to form a double layer to store charges. The high specific surface area of ​​the residual oil-derived activated carbon provides a large number of charge storage sites, thereby improving the energy storage capacity of the supercapacitor.

[0024] Ordinary activated carbon purchased on the market was selected as a comparative example, and the residue oil-derived activated carbon products prepared in Example 1 and Example 2 of the present application and ordinary activated carbon were placed under the condition of a formaldehyde concentration of 0.1 mg / m3 for formaldehyde adsorption capacity test, and abrasion resistance (test standard is national standard GB / T30202.3-2013) and compressive strength (test standard is GB / T30202.3-2013) tests were performed at the same time. The results are shown in Table 1 below: Table 1 Test results

[0025] It can be seen from Table 1 above that the residual oil-derived activated carbon prepared in the present invention is significantly superior to ordinary activated carbon in terms of adsorption capacity, abrasion resistance and compressive strength.

[0026] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing residual oil-derived activated carbon by a two-step pyrolysis method, characterized in that: The following steps are involved: Step 1: Select the residual oil produced in the petroleum refining process as the raw material, and perform dehydration, crushing, screening and desulfurization pretreatment on the selected residual oil raw material in sequence to obtain a relatively clean residual oil raw material; Step 2: placing the pretreated residual oil raw material into a carbonization device, heating it in an inert gas to cause a pyrolysis reaction of the residual oil raw material, completing the primary pyrolysis treatment, forming gaseous products and liquid products for recycling, and the solid residue formed is the preliminary carbonized product; Step 3: Mix the carbon dioxide with the preliminary carbonized product, and perform preliminary heating activation at a temperature of 700 to 1000° C., and then perform secondary heating deactivation on the preliminary carbonized product after the preliminary heating activation treatment by a chemical activation method to form an activated carbon semi-finished product; Step 4: placing the activated carbon semi-finished product in an inert atmosphere and cooling it to room temperature, then washing the activated carbon semi-finished product with deionized water, and drying it after washing to obtain a residual oil-derived activated carbon finished product.

2. The method for preparing residual oil-derived activated carbon by double-step pyrolysis according to claim 1, characterized in that: In the step 1, the specific steps of pre-treating the residual oil raw material by dehydration are: firstly placing the residual oil raw material in a centrifuge for centrifugal treatment, using centrifugal force to initially separate the water from the residual oil raw material, and then placing the residual oil raw material in a vacuum environment and heating it until the water evaporates.

3. The method for preparing residual oil-derived activated carbon by double-step pyrolysis according to claim 1, characterized in that: In the step 1, the specific steps of crushing and screening the dehydrated residual oil raw material are as follows: first, the residual oil raw material after dehydration pretreatment is added to a crusher for crushing treatment, and the crushed material obtained after the crushing treatment is added to a screening machine for screening, and the particle size of the residual oil raw material that passes the screening is controlled to be 85-125 meshes.

4. The method for preparing residual oil-derived activated carbon by double-step pyrolysis according to claim 1, characterized in that: In the step 1, the specific steps of performing desulfurization pretreatment on the residual oil raw material after crushing and screening pretreatment are: introducing hydrogen into the residual oil raw material to react the sulfide therein with the hydrogen to generate hydrogen sulfide, and then separating the hydrogen sulfide from the residual oil raw material to complete the desulfurization pretreatment.

5. The method for preparing residual oil-derived activated carbon by double-step pyrolysis according to claim 1, characterized in that: In the step 2, the residual oil raw material is heated in nitrogen or argon at a heating rate of 10-15°C / min, and the heating is stopped when the temperature reaches 400-600°C and kept at this temperature for 60-75 minutes.

6. The method for preparing residual oil-derived activated carbon by double-step pyrolysis according to claim 1, characterized in that: In the step three, the specific steps of using the chemical activation method to perform secondary heating deactivation on the preliminary carbonized product are: first, the preliminary carbonized product that has been initially heated and activated is mixed with an activator, and stirred and immersed in a heating environment of 80 to 90° C. for 12 to 16 hours, and then the immersed mixture is placed in an activation equipment and maintained at an activation temperature of 600 to 800° C. for 60 to 75 minutes.

7. The method for preparing residual oil-derived activated carbon by double-step pyrolysis according to claim 6, characterized in that: The mixing mass ratio of the preliminary carbonized product to the activator is 1:1, and the activator is selected from one of phosphoric acid and potassium hydroxide.

8. The method for preparing residual oil-derived activated carbon by double-step pyrolysis according to claim 1, characterized in that: In the step 4, the activated carbon semi-finished product is placed in nitrogen or carbon dioxide for cooling, the resistivity of the deionized water is higher than 18 MΩ·cm, the activated carbon semi-finished product is completely immersed in deionized water and repeatedly washed three times, and after washing, the activated carbon semi-finished product is placed in a drying oven at a temperature of 100 to 150° C. for drying.

9. Application of residual oil-derived activated carbon prepared by a double-step pyrolysis method, characterized in that: The residual oil-derived activated carbon is used as an electrode material in a supercapacitor.

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