A method for preparing activated carbon by treating rectification still residue with low-temperature plasma

Abstract

The application discloses a method for preparing activated carbon by treating rectifying still residues with low-temperature plasma, which comprises the following steps: putting dry rectifying still residues into a low-temperature plasma generating device, and introducing working gas; adjusting the discharge power of the low-temperature plasma generating device to carry out discharge treatment, so that the working gas is converted into low-temperature plasma at room temperature, and the rectifying still residues generate activated carbon in the atmosphere of the low-temperature plasma. The method for preparing activated carbon by treating rectifying still residues with low-temperature plasma forms various active particles with oxidation capacity in the treatment process, destroys the covalent bonds of organic matters in the rectifying still residues at room temperature, and the generated ultraviolet photons make the shared electron pairs in the covalent bonds absorb the photons and enter into an excited state, and the absorbed energy of the molecules in the excited state when returning to the ground state makes the covalent bonds break and recombine, and generates covalent bonds with higher binding energy, so that the H, O, P, N and other heteroatoms in the organic matters are removed, and the activated carbon with rich porosity is obtained.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of preparation of industrial waste-based activated carbon, and particularly relates to a method for preparing activated carbon by treating rectification still residue with low-temperature plasma. BACKGROUND

[0002] Rectification is a very important operation unit in chemical separation process, and is widely used in different industries such as coal chemical industry, petroleum chemical industry, fine chemical industry, and pharmaceutical chemical industry. However, rectification still residue is inevitably produced in the rectification process. The rectification still residue is a dangerous organic waste, which will harm the nature and human health if not properly treated. At present, the main disposal method of rectification still residue is harmless treatment. CN107514641A adopts oxidation incineration method to treat rectification still residue. This method is carried out at about 1000℃, which needs to consume a large amount of natural gas and puts forward strict requirements for the equipment material, and the economic benefit is poor.

[0003] Since the rectification still residue contains a large amount of carbon elements, how to reduce the accumulation of rectification still residue and its negative impact on the ecological environment, and even achieve the purpose of resource utilization of rectification still residue and waste treatment, has become a problem to be solved in the treatment process of rectification still residue. At present, the resource utilization methods of rectification still residue mainly include recovery of specific organic matter, such as: CN114805422A recovers silicon ether from alkylamine rectification still residue by alkaline hydrolysis reflux, but only specific still residue is recovered, which cannot be treated on a large scale. CN114408921A discloses a method for preparing activated carbon from rectification still residue. The method first calcines the rectification still residue, and then activates it at high temperature to prepare activated carbon. The obtained activated carbon has rich pores, but the waste gas generated in the calcination process contains tar and other macromolecular organic pollutants, which are difficult to treat and are easy to cause secondary pollution. In addition, in the process of calcining the rectification still residue, the carbon source is lost, resulting in low yield of activated carbon. At the same time, the method cannot finely control the pores of the activated carbon.

[0004] In summary, the known methods for preparing activated carbon from rectification still residue still have many shortcomings, and it is urgent to develop a simple and high-yield technology for preparing activated carbon from rectification still residue. SUMMARY

[0005] The present application aims to provide a method for preparing activated carbon by treating rectification still residue using low-temperature plasma, which utilizes the strong electric field generated during discharge to excite the valence electrons in the covalent bonds of organic matter, thereby causing the chemical bonds in the organic matter to break, and larger organic molecules to be converted into small molecules, and the high-energy electrons and active radicals in the generated plasma to chemically react with the organic matter in the rectification still residue, causing the C-H, C-O, C=O, C=C and C-X (X represents a halogen atom) covalent bonds in the organic matter in the rectification still residue to break and generate C, H, O, N, ·OH and X particles, which are then recombined in the plasma atmosphere to generate small molecule substances such as activated carbon, H2O, H2, CH4, NO Y , and CO Y (Y represents the coordination number of oxygen elements, Y=1, 2) and other small molecule substances, and the heteroatomic components are converted into corresponding acids or inorganic salts, and the generated NO Y , and CO Y are decomposed into O2, N2 and C elements in the plasma environment, and the small molecule gases are carried out of the reaction system by the carrier gas, so that the generated elemental carbon forms activated carbon under the action of the plasma gas and is retained in the reaction system. The method of the present application not only disposes of the rectification still residue, but also prepares activated carbon, and is a new type of green rectification still residue resource utilization technology under low-temperature operation, which is helpful to realize the green and high-quality development of the petroleum and chemical industry.

[0006] The purpose of the present application is achieved by the following technical solutions:

[0007] A method for preparing activated carbon by treating rectification still residue using low-temperature plasma, comprising: drying the rectification still residue, placing the dried rectification still residue into a low-temperature plasma generating device, and introducing working gas; adjusting the discharge power of the low-temperature plasma generating device to perform discharge treatment, so that the working gas is converted into low-temperature plasma at room temperature, and the rectification still residue generates activated carbon in the atmosphere of the low-temperature plasma.

[0008] The rectification still residue includes at least one of benzene series rectification still residue, turpentine rectification still residue, cracking gasoline still residue, alcohol amine rectification still residue, amide rectification still residue, phenol formaldehyde still residue, or petroleum rectification still residue. The rectification still residue contains a large amount of macromolecular organic matter and has the characteristic of high carbon content. The carbon element content in the dried rectification still residue is 40-75 wt%, and the elements C, H, O, N, X, etc. are mainly present. In the low-temperature plasma treatment process, the covalent bonds formed by the above elements are easily broken by plasma, thereby forming cleaner activated carbon.

[0009] The solid content of the dry distillation residue is greater than or equal to 99 wt%. By controlling the solid content of the distillation residue, the competition absorption of the active substances in the plasma by the residual liquid substances such as water in the distillation residue can be avoided, and the treatment efficiency of the low-temperature plasma and the distillation residue can be increased.

[0010] The working gas is selected from one of oxygen, nitrogen, air, carbon dioxide or argon. In the presence of oxygen, the covalent bonds of the organic matter in the distillation residue are more easily broken, and part of the C-C bonds are broken to generate elemental C and CO2 under the combined action of oxygen and low-temperature plasma, thereby forming a rough structure on the surface of the distillation residue and forming abundant pores in the interior, and the oxygen in the air is more conducive to the formation of pores and a larger specific surface area.

[0011] Preferably, the working gas is air.

[0012] The flow rate of the working gas is 0.10-0.50 L / min.

[0013] Preferably, the working gas is introduced 20 minutes before discharging and stopped 10 minutes after discharging.

[0014] The discharge power is 30-45 W / g. 釜残 The discharge treatment time is 60-300 minutes.

[0015] At room temperature, the distillation residue is converted into activated carbon under the action of low-temperature plasma, and the carbon yield of the activated carbon is 10%-55%.

[0016] As a further preferred scheme of the method for preparing activated carbon by treating distillation residue with low-temperature plasma according to the present application, the non-methane hydrocarbon (NMHC) content in the gas discharged from the low-temperature plasma generating device is less than 8 mg / m 3 .

[0017] The present application has the following advantages:

[0018] (1) The present application provides a simple and efficient treatment method to address the problems of difficult disposal of existing distillation residue, serious pollution by incineration, and difficulty in preparing activated carbon and high treatment temperature. The method can effectively convert distillation residue into activated carbon, has low energy consumption, and can realize the resource recycling of distillation residue.

[0019] (2), the present application is based on the characteristics of low-temperature plasma, such as easy to obtain, small heat, low requirement for equipment, high energy efficiency, and the like, and utilizes the characteristics of the distillation residue that it has rich carbon source, and adopts the low-temperature plasma to treat the distillation residue to prepare the activated carbon, and in the treatment process, various active particles are formed, such as ·OH, ·H, ·O, ·O2, ·HO2, H2O2, O3 and high-energy electrons, and the like, and these active particles have high oxidation capacity, can destroy the covalent bond of the organic matter in the distillation residue at room temperature, and the ultraviolet photons generated make the shared electron pair in the covalent bond absorb the photons to enter the excited state, and the energy absorbed when the excited state molecules return to the ground state makes the covalent bond in the molecules break and recombine, and higher covalent bond energy is generated, so that the H, O, P, N and other heteroatoms in the organic matter are removed, and the activated carbon with rich porosity is obtained.

[0020] (3), the plasma reactor of the present application operates at room temperature, and the process of preparing the activated carbon will not produce tar, and secondary pollution can be avoided. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a scanning electron microscope image of the activated carbon prepared in Example 4. DETAILED DESCRIPTION

[0022] The method for preparing the activated carbon by treating the distillation residue with low-temperature plasma is as follows: after the distillation residue is dried, it is put into a plasma generating device, working gas is introduced, and the distillation residue is treated by adjusting the discharge time, power and gas flow of the device, and the activated carbon material is obtained after the discharge is completed.

[0023] The technical solutions of the present application are further described below through specific embodiments.

[0024] The yield of the activated carbon is calculated according to formula (1):

[0025]

[0026] Example 1

[0027] The method for preparing the activated carbon by treating the distillation residue with low-temperature plasma is as follows: after the distillation residue is dried, it is put into a plasma generating device, working gas is introduced, and the distillation residue is treated by adjusting the discharge time, power and gas flow of the device, and the activated carbon material is obtained after the discharge is completed.

[0028] 10g of turpentine distillation residue is dried in a dryer, and the water content of the distillation residue is dried to 0.8wt%, and the remaining is solid. The main component of the dried turpentine distillation residue is macrocyclic diterpene hydrocarbon, accounting for 78wt% of the turpentine distillation residue, and the carbon element content is 54.28%. The dried turpentine distillation residue is put into a low-temperature plasma generating device, the chamber door is closed, and argon is introduced as the working gas of the low-temperature plasma device 20min before discharge, and the flow rate of the working gas (i.e. the gas flow rate for treating unit mass of distillation residue per unit time) is 0.20L / (min·g釜残 ), the output power of the low-temperature plasma generating device was regulated to be 330 W, the discharge treatment was carried out at room temperature for 60 min, and the argon gas was stopped 10 min after the discharge ended; 1.3623 g of activated carbon was obtained, which was recorded as Ar-0.20-330, wherein 0.20 represents the argon gas flow in the low-temperature plasma generating device, and 330 represents the output power of the low-temperature plasma generating device.

[0029] The non-methane hydrocarbons (NMHC) in the gas discharged from the low-temperature plasma generating device were detected at the same time.

[0030] Example 2

[0031] The low-temperature plasma was used to treat the chemical rectifying still residue to prepare activated carbon, including the following steps:

[0032] 10 g of the amide rectifying still residue was dried in a dryer, and the water content of the dried rectifying still residue was 0.6 wt%, and the rest was solid. The main component of the dried amide rectifying still residue was dimethylformamide, accounting for 54 wt% of the amide rectifying still residue, and the carbon element content was 42.96%. The dried amide rectifying still residue was placed in the low-temperature plasma generating device, the chamber door was closed, and the carbon dioxide gas was introduced as the working gas of the low-temperature plasma device 20 min before the discharge, and the flow rate of the working gas was 0.40 L / (min·g 釜残 ), the output power of the low-temperature plasma generating device was regulated to be 360 W, the discharge treatment was carried out at room temperature for 120 min, and the carbon dioxide gas was stopped 10 min after the discharge ended; 2.1978 g of activated carbon was obtained, which was recorded as CO2-0.40-360, wherein 0.40 represents the carbon dioxide gas flow in the low-temperature plasma generating device, and 360 represents the output power of the low-temperature plasma generating device.

[0033] Example 3

[0034] The low-temperature plasma was used to treat the chemical rectifying still residue to prepare activated carbon, including the following steps:

[0035] 10 g of the amide rectifying still residue was dried in a dryer, and the water content of the dried rectifying still residue was 0.6 wt%, and the rest was solid. The main component of the dried amide rectifying still residue was dimethylformamide, accounting for 54 wt% of the amide rectifying still residue, and the carbon element content was 42.96%. The dried amide rectifying still residue was placed in the low-temperature plasma generating device, the chamber door was closed, and the carbon dioxide gas was introduced as the working gas of the low-temperature plasma device 20 min before the discharge, and the flow rate of the working gas was 0.40 L / (min·g 釜残), and the output power of the low-temperature plasma device was regulated to be 390 W. After discharging treatment for 180 min at room temperature (stopping the air flow 10 min after the discharging ended), 3.9420 g of activated carbon was obtained, which was recorded as N2-0.10-390, wherein 0.10 represented the air flow in the low-temperature plasma device, and 390 represented the output power of the low-temperature plasma device.

[0036] Example 4

[0037] The method for preparing activated carbon by treating chemical rectification still residue by low-temperature plasma includes the following steps:

[0038] The 10 g of phenolic rectification still residue was dried in a dryer. After drying, the water content of the rectification still residue was 0.8 wt%, and the rest was solid. The main component of the dried phenolic rectification still residue was phenolic resin, accounting for 63 wt% of the phenolic rectification still residue, and the carbon element content was 71.34%. The dried rectification still residue was placed in a low-temperature plasma generating device, the chamber door was closed, and air was introduced as the working gas of the low-temperature plasma device 20 min before discharging. The flow rate of the working gas (i.e., the gas flow rate for treating unit volume of rectification still residue per unit time) was 0.50 L / (min·g 釜残 ), and the output power of the low-temperature plasma device was regulated to be 420 W. After discharging treatment for 240 min at room temperature (stopping the air flow 10 min after the discharging ended), 5.3364 g of activated carbon was obtained, which was recorded as Air-0.50-420, wherein 0.50 represented the air flow in the low-temperature plasma device, and 420 represented the output power of the low-temperature plasma device.

[0039] From Figure 1 It can be seen that the activated carbon prepared from the phenolic rectification still residue in this example, Air-0.50-420, has a rough morphology, indicating that it has abundant pores, a larger specific surface area, and stronger adsorption performance.

[0040] Comparative Example 1

[0041] The method for preparing activated carbon by treating chemical rectification still residue by low-temperature plasma includes the following steps:

[0042] The 11.0222 g of undried phenolic rectification still residue (the main component was phenolic resin, accounting for 57.16 wt% of the phenolic rectification still residue, and the carbon element content was 64.72%, and the water content was 10.0 wt%) was placed in a low-temperature plasma generating device, the chamber door was closed, and air was introduced as the working gas of the low-temperature plasma device 20 min before discharging. The flow rate of the working gas (i.e., the gas flow rate for treating unit volume of rectification still residue per unit time) was 0.50 L / (min·g 釜残), the output power of the low-temperature plasma generating device was regulated to be 420 W, and after discharging treatment for 240 min at room temperature (stopping the oxygen flow 10 min after the end of discharging), 1.8742 g of activated carbon was obtained, which was recorded as Air-0.50-420-10, wherein 0.50 represents the air flow in the low-temperature plasma generating device, 420 represents the output power of the low-temperature plasma generating device, and 10 represents the water content of the phenolic distillation residue.

[0043] Example 5

[0044] The method for preparing activated carbon by treating a chemical distillation residue by low-temperature plasma includes the following steps:

[0045] 10 g of benzene residue was placed in a dryer for drying. After drying, the water content of the distillation residue was 0.7 wt%, and the remaining was solid. The main component of the dried benzene residue was C6-C 10 aromatic hydrocarbons, accounting for 65 wt% of the benzene residue, and the carbon content was 64.33%. The dried distillation residue was placed in a low-temperature plasma generating device, the chamber door was closed, and oxygen was introduced as the working gas of the plasma device 20 min before discharging, and the gas flow (i.e. the gas flow per unit volume of distillation residue per unit time) was 0.30 L / (min·g 釜残 ), the output power of the low-temperature plasma generating device was regulated to be 450 W, and after discharging treatment for 300 min at room temperature (stopping the oxygen flow 10 min after the end of discharging), 3.0217 g of activated carbon was obtained, which was recorded as O2-0.30-450, wherein 0.30 represents the oxygen flow in the low-temperature plasma generating device, and 450 represents the output power of the low-temperature plasma generating device.

[0046] The BET data, carbon yield, and non-methane total hydrocarbon concentration in the tail gas of the five activated carbons prepared in Examples 1-5 and Comparative Example 1 are shown in Table 1 below.

[0047] Table 1. BET, carbon yield, and non-methane total hydrocarbon concentration in the tail gas of the activated carbons prepared in Examples 1-5 and Comparative Example 1

[0048]

[0049]

[0050] As can be seen from Table 1, the present application can prepare activated carbon with excellent performance by using different chemical distillation residue as carbon source. The activated carbon prepared in Examples 1-5 all have good performance, especially the activated carbon prepared in Example 4 using phenolic distillation residue as raw material and the activated carbon prepared in Example 5 using benzene series distillation residue as raw material have higher specific surface area and pore volume, and the activated carbon prepared in Example 4 has higher carbon yield. At the same time, the performance of the activated carbon prepared in the present application is similar to that of the commercial activated carbon with excellent performance (specific surface area of 1000-2000 m 2 / g) and oxidase activated carbon (specific surface area of 3000-4000 m 2 / g), and there is no obvious difference.

[0051] As can be seen from Example 4 and Comparative Example 1, under the same reaction conditions, the water content of phenolic distillation residue has a great influence on the specific surface area of activated carbon, etc. When the distillation residue contains more water, a thick water film will be formed on the surface of the distillation residue, so that the active particles such as high-energy electrons, ·OH, ·O, etc. produced will be captured by the water film, reducing the contact area of the active particles with the residue, and the thick water film will block the active ions from entering the inside of the residue, resulting in insufficient reaction and small pore volume. In Example 4, the distillation residue is dried to a water content of only 0.8 wt%, at this time the water content in the distillation residue is significantly reduced, a thin water film is formed on the surface of the distillation residue, and after the active particles are captured, the water film plays a role of enrichment, thereby increasing the contact and reaction opportunities of active substances with organic matter and improving the utilization efficiency of active substances.

Claims

1. A method for preparing activated carbon using low-temperature plasma treatment of rectifier still residue, characterized by, The distillation residue is dried, and the dried distillation residue is put into a low-temperature plasma generating device and working gas is introduced into the device. The discharge power of the low-temperature plasma generating device is adjusted, and the working gas is converted into low-temperature plasma at room temperature through discharge treatment, and the distillation residue is converted into activated carbon in the atmosphere of the low-temperature plasma; wherein the content of carbon element in the dried distillation residue is 40-75 wt %, and the solid content of the dried distillation residue is ≥99 wt %. The distillation residue includes at least one of benzene series distillation residue, turpentine distillation residue, cracking gasoline residue, alcohol amine distillation residue, amide distillation residue, phenol formaldehyde residue or petroleum distillation residue.

2. The method of claim 1, wherein the low temperature plasma treatment is performed at a temperature of 100 to 300 °C. The working gas is selected from air.

3. The method of claim 1, wherein the low temperature plasma treatment is performed at a temperature of 100 to 300 °C. The working gas is selected from one of oxygen, nitrogen, air, carbon dioxide and argon, and the flow rate of the working gas is 0.10-0.50 L / (min x g 釜残 ).

4. The method of claim 3, wherein the low-temperature plasma treatment is performed at a temperature of 100 to 300 °C. The working gas is introduced 20 minutes before discharge, and the introduction of the working gas is stopped 10 minutes after the discharge ends.

5. The method of claim 1, wherein the low temperature plasma treatment is performed at a temperature of 100-300 °C. The discharge power is 30-45 W / g 釜残 The discharge treatment time is 60-300 min.

6. The method of claim 1, wherein the low temperature plasma treatment is performed at a temperature of 100-300 °C. ​ 7. The method of claim 1, wherein the low temperature plasma treatment is performed at a temperature of about 100°C to about 300°C. The low-temperature plasma generating apparatus discharges a gas having a non-methane hydrocarbon content of less than 8 mg / m 3 .

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