A multi-level porous activated carbon and a preparation method thereof

Abstract

The application discloses a kind of multi-level hole active carbon and preparation method thereof, and active carbon is core-shell structure, including core layer and shell layer, multi-level hole active carbon simultaneously has micropore-mesopore-macropore structure.The preparation method of the multi-level hole active carbon first mixes petroleum coke and activating agent uniformly and then carries out pre-activation treatment, obtains pre-activated petroleum coke;Then second carbon source, alkaline earth metal compound, activating agent and pre-activated petroleum coke are mixed uniformly and then activated, after activation, porous active carbon is obtained by washing and drying.The preparation method of the present application solves the problem that the micropore ratio of the active carbon prepared by using petroleum coke as raw material is too high, and the mesopore and macropore ratio is low, realizes the preparation of multi-level hole active carbon by using petroleum coke as raw material, and improves the mesopore and macropore ratio of the active carbon.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of carbon materials, and particularly relates to a multi-stage pore activated carbon and a preparation method thereof. BACKGROUND

[0002] The activated carbon is prepared from wood, coal, petroleum coke and other carbon-containing raw materials through pyrolysis and activation processes, has a developed pore structure, a large specific surface area and rich surface chemical groups, and has been successfully applied in adsorption, catalysis, double-layer capacitor electrode materials and the like.

[0003] As a solid by-product of the petroleum processing process, petroleum coke is in a large quantity, especially high-sulfur coke, which is currently used as fuel for combustion only, and the selling price is only about 100 yuan / ton. Under the background of carbon neutralization and carbon peak, even the sale is prohibited, so the high-value utilization of petroleum coke becomes a new problem and challenge. The activated carbon prepared from petroleum coke has stable chemical properties, a high specific surface area, a developed pore structure and good electrical conductivity, and is suitable for use as a double-layer electrode material. However, when the petroleum coke-based activated carbon is used as an electrode material, the performance is affected by the structure and properties of the carbon material itself, and the structure-activity relationship is relatively complex, and various performances are mutually restricted.

[0004] The pore size distribution range of the activated carbon is very wide, from less than 1 nm to several thousand nm, and the pore size is divided into micropores less than 2 nm, mesopores of 2-50 nm and macropores greater than 50 nm. When the activated carbon is used as an electrode material, according to the double-layer theory model, the specific capacitance of the activated carbon is proportional to the specific surface area, but in fact, the two do not present a linear relationship. The pore structure of the activated carbon can form a stable double layer only after being fully infiltrated by the electrolyte, so the matching degree of the pore structure of the activated carbon and the electrolyte ions is particularly important.

[0005] Patent CN112028074A discloses a hierarchical pore activated carbon adjustable control method and application. Biomass is carbonized by hydrothermal synthesis method, and then immersed in calcium chloride solution for carbon dioxide activation, which can increase the proportion of macropores in activated carbon, obtain hierarchical pore activated carbon, solve the problem that the pore size of activated carbon is difficult to control in the prior art, and even if hierarchical pores can be obtained, the specific surface area is sacrificed. The preparation method is complex, and the improvement of the proportion of mesopores and macropores depends on the hydrothermal synthesis process. Patent CN110902681A discloses a method for improving the porosity of low-quality activated carbon. The low-quality biomass activated carbon is used as raw material, and the low-quality activated carbon with low porosity and high micropore ratio is expanded by pyrolysis in a short-chain alkane atmosphere and reduction in a reducing atmosphere. The method can obtain activated carbon with high porosity, high mesopore and macropore ratio, but the method has limitations. It can only re-regulate the pore structure of biomass carbon with relatively loose structure, and has no effect on the re-expansion of carbon materials with dense structure. Patent CN111892052A discloses a pore size repair and control method of activated carbon. Formaldehyde and phenol are used as precursors to synthesize phenolic resin in the pores of activated carbon, and carbonization at high temperature is realized. The conversion of macropores and mesopores to mesopores and micropores further improves the specific surface area, mesopore ratio and micropore ratio of activated carbon. This method can repair and control the pore size of activated carbon to a certain extent, but it is only suitable for activated carbon with high macropore and mesopore ratio, and has certain limitations. Patent CN105645410A provides a preparation method of 3D network pore structure supercapacitor carbon. Wood biomass is used as raw material, and zinc chloride is immersed, then KOH activation is carried out, and finally water vapor activation is carried out for refining treatment of activated carbon pore structure. Although the obtained activated carbon has different proportions of macropores, mesopores and micropores, the preparation method of activated carbon is complex, and it is only suitable for the process of preparing activated carbon from wood biomass. SUMMARY

[0006] At present, most of the pore size control technologies of activated carbon are based on carbon precursors such as biomass and other raw materials. By introducing other substances during carbonization and activation, the pore size can be adjusted. However, these methods are not suitable for the activation process of petroleum coke raw material which has been highly carbonized to prepare activated carbon. It is impossible to further control the pore size.

[0007] In view of the deficiencies in the prior art, the present application provides a kind of multi-level hole active carbon and its preparation method, with petroleum coke as raw material to prepare the multi-level hole active carbon with core-shell structure, wherein macropore and mesopore are concentrated in shell layer, and the core layer is mainly microporous.The present application solves the problem that the active carbon prepared by using petroleum coke as raw material has too high micropore ratio and low mesopore and macropore ratio, realizes the preparation of multi-level hole active carbon using petroleum coke as raw material, and improves the mesopore and macropore ratio of active carbon.The prepared multi-level hole active carbon can be applied to supercapacitor, provides abundant space for the preparation of carbon-carbon composite material, carbon-metal oxide composite material, and widens the range of application of petroleum coke-based active carbon in other fields.

[0008] In order to achieve the above technical purpose, the first aspect of the present application provides a kind of multi-level hole active carbon, the active carbon is core-shell structure, including core layer and shell layer, wherein the core layer active carbon comes from the first carbon source, the first carbon source is petroleum coke, the shell layer active carbon comes from the second carbon source, the second carbon source is one or several of pitch, catalytic oil slurry and heavy hydrocarbon-containing material, the multi-level hole active carbon has micropore-mesopore-macropore structure at the same time, the pore size distribution is as follows: the proportion of macropore with pore size greater than 50nm is 1% to 35%, preferably 5% to 30%; The proportion of mesopore with pore size of 2 to 50nm is 4% to 80%, preferably 10% to 70%; The proportion of micropore with pore size less than 2nm is 10% to 95%, preferably 40% to 80%; And macropore and mesopore are concentrated in shell layer, and micropore is concentrated in core layer, wherein the proportion of macropore and mesopore in shell layer is 40% to 90%, preferably 50% to 90%; The proportion of micropore in core layer is 70% to 99%, preferably 80% to 99%.

[0009] In the above-mentioned multi-level hole active carbon, the specific surface area of the multi-level hole active carbon is 400 to 3000m 2 / g, preferably 900 to 2500m 2 / g.

[0010] In the above-mentioned multi-level hole active carbon, the total pore volume of the multi-level hole active carbon is 0.3 to 2.5cm 3 / g, preferably 0.6 to 2.5cm 3 / g.

[0011] In order to achieve the above technical purpose, the second aspect of the present application provides a kind of preparation method of multi-level hole active carbon, comprising the following steps:

[0012] (1) mixing petroleum coke and activator uniformly and then performing pre-activation treatment to obtain pre-activated petroleum coke;

[0013] (2) mixing the second carbon source, the alkaline earth metal compound, and the activating agent with the pre-activated petroleum coke obtained in step (1), uniformly mixing, and then performing activation treatment, and after the activation is completed, washing and drying to obtain the porous activated carbon.

[0014] Further, in the preparation method of the multi-level pore activated carbon, the activating agent in step (1) is the same as or different from the activating agent in step (2), and is preferably the same. The activating agent is selected from one or more of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, calcium hydroxide, and magnesium hydroxide, and is preferably one or more of sodium hydroxide, potassium hydroxide, and potassium carbonate.

[0015] Further, in the preparation method of the multi-level pore activated carbon, the petroleum coke raw material in step (1) is a solid product generated in the thermal conversion production process of a heavy petroleum distillate, and the particle size of the petroleum coke raw material is generally 10-500 μm, and is preferably 30-300 μm.

[0016] Further, in the preparation method of the multi-level pore activated carbon, the volatile content of the petroleum coke raw material is generally between 5wt% and 20wt%.

[0017] Further, in the preparation method of the multi-level pore activated carbon, the weight ratio of the petroleum coke raw material to the activating agent in step (1) is 1:0.2-1:10, and is preferably 1:0.5-1:5.

[0018] Further, in the preparation method of the multi-level pore activated carbon, the pre-activation treatment in step (1) is performed in an inert atmosphere, and the inert atmosphere can be one or more of nitrogen, helium, neon, argon, krypton, and xenon. Generally, before the pre-activation treatment, the gas in the device for activation is fully replaced with the inert atmosphere.

[0019] Further, in the preparation method of the multi-level pore activated carbon, the pre-activation temperature in step (1) is 200-550°C, and is preferably 300-500°C.

[0020] Further, in the preparation method of the multi-level pore activated carbon, the pre-activation time in step (1) is 20-150 min, and is preferably 40-120 min.

[0021] Further, in the preparation method of the multi-level pore activated carbon, the volatile component mainly composed of heavy oil is uniformly released from the inner and outer surfaces of the petroleum coke during the pre-activation process in step (1), and exists in the activation furnace in the form of liquid with certain viscosity, lubricates the petroleum coke body, and forms uniform infiltration and wrapping on the inner and outer surfaces. At the same time, the activation agent (for example, potassium hydroxide) has a weak activation reaction with the oxygen-containing functional groups on the surface of the petroleum coke, the potassium hydroxide begins to melt, and a dehydration reaction occurs, the contact between the potassium hydroxide and the petroleum coke body becomes more and more sufficient, and a large number of active sites are introduced into the surface and the interior of the raw material, laying a foundation for subsequent activation.

[0022] Further, in the preparation method of the multi-level pore activated carbon, the second carbon source in step (2) can be one or more of pitch, catalytic oil slurry, and heavy hydrocarbon-containing material, and is preferably pitch. The pitch is one or more of petroleum pitch and coal tar pitch, and is preferably petroleum pitch. Further, the softening point of the petroleum pitch is 80-350°C, and is preferably 200-300°C. The toluene insoluble content of the petroleum pitch is 20%-95%, and is preferably 50%-80%. The distillation range of the heavy hydrocarbon-containing material is 350-700°C, and is preferably 350-600°C. The aromatic content is 35wt%-99wt%, and is preferably 45wt%-90wt%. Specifically, the heavy hydrocarbon-containing material can be one or more of residual oil, ethylene tar, coal tar, and catalytic cracking oil slurry. Further preferably, the heavy hydrocarbon-containing material can be one or more of catalytic cracking oil slurry and ethylene tar.

[0023] Further, in the preparation method of the multi-level pore activated carbon, the alkali earth metal compound in step (2) has a thermal decomposition temperature of not more than 1000°C. The decomposition temperature refers to the temperature at which the compound undergoes a chemical decomposition reaction. The particle size of the alkali earth metal compound is 1nm-1μm.

[0024] Further, in the preparation method of the multi-level pore activated carbon, the alkali earth metal compound in step (2) can be one or more of alkali earth metal oxalates, alkali earth metal carbonates, alkali earth metal nitrates, alkali earth metal acetates, alkali earth metal hydroxides, and alkali earth metal citrates. Specifically, the alkali earth metal compound can be one or more of calcium nitrate, magnesium nitrate, strontium nitrate, calcium oxalate, magnesium oxalate, calcium carbonate, magnesium carbonate, calcium acetate, magnesium acetate, calcium citrate, magnesium citrate, calcium bicarbonate, magnesium bicarbonate, basic magnesium carbonate, and basic calcium carbonate. Preferably, the alkali earth metal compound can be one or more of calcium nitrate, magnesium nitrate, calcium oxalate, magnesium oxalate, calcium carbonate, magnesium carbonate, calcium acetate, magnesium acetate, calcium citrate, magnesium citrate, calcium bicarbonate, magnesium bicarbonate, calcium hydroxide, and magnesium hydroxide.

[0025] Further, in the preparation method of the multi-level pore activated carbon, the mass ratio of the second carbon source to the petroleum coke raw material in step (2) is 1:20-1:0.1, preferably 1:10-1:0.2.

[0026] Further, in the preparation method of the multi-level pore activated carbon, the mass ratio of the second carbon source to the alkaline earth metal compound in step (2) is 1:0.5-1:20, preferably 1:0.8-1:16.

[0027] Further, in the preparation method of the multi-level pore activated carbon, the mass ratio of the second carbon source to the activating agent in step (2) is 1:5-1:0.5, preferably 1:3-1:1.

[0028] Further, in the preparation method of the multi-level pore activated carbon, when the second carbon source, the alkaline earth metal compound and the activating agent are mixed with the pre-activated petroleum coke obtained in step (1) in step (2), the second carbon source, the alkaline earth metal compound and the activating agent are preferably mixed uniformly and crushed, preferably to a particle size of less than 50 microns, and then mixed with the pre-activated petroleum coke.

[0029] Further, in the preparation method of the multi-level pore activated carbon, the activation treatment in step (2) includes two-stage activation treatment, wherein the first-stage activation treatment temperature is 80-500°C, preferably 100-400°C; the first-stage activation time is 20-100 min, preferably 20-60 min; the second-stage activation temperature is 700-1000°C, preferably 700-900°C; and the second-stage activation time is 20-120 min, preferably 20-100 min.

[0030] Further, in the preparation method of the multi-level pore activated carbon, in the first-stage activation treatment process, the second carbon source is softened by heat and exists in a liquid state with a certain viscosity in the activation device, and forms a uniform mixed slurry with the alkaline earth metal compound and the activating agent, uniformly wraps the pre-activated petroleum coke, and forms a large number of initial morphological distributions with petroleum coke particles as the core and the second carbon source slurry as the shell.

[0031] Further, in the preparation method of the multi-level pore activated carbon, in the second-stage activation treatment process, due to the simultaneous activation of the petroleum coke and the second carbon source, the radial activation reaction of the activating agent in the pre-activated petroleum coke and the petroleum coke, the carbon atoms on the active sites in the petroleum coke are first oxidized to form a large number of microporous structures, and sufficient radial activation occurs. With the increase of the activation temperature, the molten potassium hydroxide further penetrates into the internal pore diameter of the petroleum coke, and the alkali metal vapor generated in the activation reaction travels between the carbon matrix microcrystal layers, and the pore structure of the petroleum coke becomes more developed, and a certain degree of transverse pore expansion occurs, realizing the conversion of the petroleum coke to the activated carbon with rich microporous structure.

[0032] Further, in the preparation method of the multi-level pore activated carbon, during the second activation process, the volatile components in the second carbon source are cracked or undergo polycondensation reaction, and the uniformly entrained alkaline earth metal compound is decomposed in situ to form nano-sized alkaline earth metal oxide under high temperature conditions, which acts as a template for the in-situ polycondensation carbon uniformly distributed during the carbonization and activation of the second carbon source. At the same time, the second carbon source, the newly generated polycondensation carbon and the activator interact significantly, and as the volatile components in the second carbon source and the alkaline earth metal compound decompose and escape, a rich micro-mesopore structure is generated.

[0033] Further, in the preparation method of the multi-level pore activated carbon, the washing in step (2) includes acid washing and water washing, and the alkaline substances and alkaline earth metal oxide generated during the reaction are removed through the acid washing and water washing processes to expose the mesopores and macropores formed during the activation process. In the acid washing, an acid solution is used for washing, and the acid is one or more of hydrochloric acid, nitric acid, sulfuric acid and acetic acid. The mass fraction of the acid solution is 0.5% to 20%, and is preferably 1% to 10%. The mass ratio of the acid solution to the solid product is 5:1 to 30:1, and is preferably 5:1 to 20:1. In the water washing, deionized water or ultrapure water is used, and the mass ratio of water to the solid product is 10:1 to 50:1, and is preferably 10:1 to 30:1.

[0034] Further, in the preparation method of the multi-level pore activated carbon, the drying temperature in step (2) is 60 to 150°C, and is preferably 60 to 120°C.

[0035] Further, in the preparation method of the multi-level pore activated carbon, the drying time in step (2) is 1 to 24 hours, and is preferably 4 to 12 hours.

[0036] The third aspect of the present application provides a multi-level pore activated carbon obtained by the above preparation method. The activated carbon has a core-shell structure, including a core layer and a shell layer. The core layer activated carbon is derived from a first carbon source, and the first carbon source is petroleum coke. The shell layer activated carbon is derived from a second carbon source, and the second carbon source is one or more of pitch, catalytic oil slurry and heavy hydrocarbon-containing material. The multi-level pore activated carbon has a micropore-mesopore-macropore structure, and the pore size distribution is as follows: the proportion of macropores with a pore size greater than 50 nm is 1% to 35%, and is preferably 5% to 30%; the proportion of mesopores with a pore size of 2 to 50 nm is 4% to 80%, and is preferably 10% to 70%; and the proportion of micropores with a pore size less than 2 nm is 10% to 95%, and is preferably 40% to 80%. The macropores and mesopores are concentrated in the shell layer, and the micropores are concentrated in the core layer. The proportion of macropores and mesopores in the shell layer is 40% to 90%, and is preferably 50% to 90%. The proportion of micropores in the core layer is 70% to 99%, and is preferably 80% to 99%.

[0037] The specific surface area of the multi-level pore activated carbon is 400-3000 m 2 / g, preferably 900-2500 m 2 / g.

[0038] The total pore volume of the multi-level pore activated carbon is 0.3-2.5 cm 3 / g, preferably 0.6-2.5 cm 3 / g.

[0039] Compared with the prior art, the present application has the following advantages:

[0040] 1. The present application provides a multi-level pore activated carbon with micropore-mesopore-macropore structure, which has a high specific surface area and adjustable pore size distribution, and has a special radial pore distribution with macropore and mesopore structure as the shell and micropore structure as the core. The activated carbon has good application prospects in the fields of adsorption, catalysis and electrochemistry.

[0041] 2. In the preparation method of the multi-level pore activated carbon, petroleum coke with high volatile content is used as the raw material for preparing the activated carbon. For the first time, the preparation process of the activated carbon is improved from the perspective of the volatile property of the petroleum coke, and the structure of the petroleum coke-based activated carbon is in-situ regulated. During the pre-activation treatment, the volatile with heavy oil as the main component is uniformly precipitated from the inner and outer surfaces of the petroleum coke under heating, and exists in the activation furnace in the form of a liquid with a certain viscosity, lubricates the petroleum coke body, and forms uniform infiltration and wrapping on the inner and outer surfaces. At the same time, the activator (for example, potassium hydroxide) reacts weakly with the oxygen-containing functional groups on the surface of the petroleum coke, and the potassium hydroxide begins to melt, dehydrates itself, and contacts the petroleum coke body more and more fully, and introduces a large number of active sites on the surface and inside of the raw material, laying a foundation for subsequent activation.

[0042] 3. In the preparation method of the multi-level pore activated carbon, the alkaline earth metal compound is in-situ decomposed into nano-sized alkaline earth metal oxide with high temperature resistance during the activation process, which can realize the uniform distribution of the alkaline earth metal oxide nanoparticles in the second carbon source, act as a hard template with large ionic radius, and can assist in adjusting the pore size structure of the activated carbon by adjusting the amount of the alkaline earth metal compound added. The pore size distribution of the petroleum coke-based activated carbon is in-situ regulated during the activation process, the proportion of mesopores and macropores is appropriately increased or decreased, and the multi-level pore activated carbon is flexibly regulated in the pore structure.

[0043] 4、The preparation method of the multi-level pore activated carbon, adopts the segmented activation mode, accurately controls the activation process and depth of different components through setting pre-activation, one-stage activation and two-stage activation, reserves different spaces for the shaping of micropores, mesopores and macropores, realizes directional and flexible control of the size and proportion of the pore diameter of the activated carbon, and solves the problem that the current petroleum coke-based activated carbon is mainly microporous structure and application is limited. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 The scanning electron microscope image of the multi-level pore activated carbon prepared for Example 1. DETAILED DESCRIPTION

[0045] The present application will be further described below in conjunction with specific embodiments. The illustrative embodiments of the present application and the description used to explain the present application are not intended to be limiting.

[0046] Unless otherwise clearly indicated, in the present specification and claims, the term "comprise" or its variations such as "comprises" or "comprising" are to be construed as including, but not excluding, the other elements or steps in addition to those described.

[0047] In this document, spatially relative terms, such as "beneath", "below", "lower", "above", "upper", and the like, can be used to describe one element's or feature's relationship to another element or feature as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" can encompass both an orientation of above and below. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative terms used herein interpreted accordingly.

[0048] In this document, the terms "first", "second", etc. are used to distinguish two different elements or portions, and are not used to define a specific position or relative relationship. In other words, in some embodiments, the terms "first", "second", etc. can also be interchanged with each other.

[0049] In this document, all numerical values of parameters (e.g. quantities or conditions) should be understood as being modified by the term "about" in all cases, whether the term "about" actually appears before the numerical value or not.

[0050] The specific surface area and pore size distribution curve of the sample is obtained by nitrogen adsorption-desorption curve on a Micromeritics ASAP2020 adsorption instrument, the operation temperature is -196 DEG C (liquid nitrogen temperature), and the sample is dehydrated and pretreated at 300 DEG C under the protection of nitrogen before testing. The specific surface area and pore size distribution are calculated by BET method and DFT method respectively.

[0051] The petroleum coke raw material used in the application has the following properties: sulfur content is 4.15wt%, volatile content is 15.79wt%, and ash content is 0.79wt%. The needle coke used is self-made in the laboratory, and the true density is 1.83g / cm 3 , the volatile content is 8.1wt%, the sulfur content is 0.2wt%, the moisture content is 0.5wt%, and the structure has wide range of streamline fibrous structure.

[0052] The petroleum pitch selected in the application has the following properties: the softening point is 215 DEG C, the toluene insoluble content is 56wt%; the anisotropic pitch has the following properties: the softening point is 270 DEG C, the toluene insoluble content is 74.1wt%, and the mesophase content is 100%; the isotropic pitch has the following properties: the softening point is 265 DEG C, the toluene insoluble content is 77.3wt%, and the mesophase content is 0.

[0053] The catalytic cracking oil slurry selected in the application has the following properties: the density is 1.0058kg / m 3 , the carbon residue value is 7.1wt%, the carbon content is 88.4wt%, and the four-component composition is: saturated fraction 32.1wt%, aromatic fraction content 54.2wt%, gum 13.2wt%, and asphaltene 0.5wt%.

[0054] The ethylene tar selected in the application has the following properties: the density at 20 DEG C is 1.198g / cm 3 , the softening point is 145 DEG C, and the carbon content is 91.81wt%.

[0055] Example 1

[0056] 20.4g of petroleum coke and 60.2g of KOH are weighed and uniformly mixed, and then loaded into a rotating body activation furnace. After the air in the activation furnace is replaced by nitrogen at a flow rate of 500mL / min for 20min, the nitrogen flow rate is 500mL / min, and after pre-activation at 400 DEG C for 60min, the heating is turned off, and the sample is taken out after cooling to room temperature.

[0057] Take 6.8g petroleum pitch, 5.7g magnesium hydroxide, 13.7g potassium hydroxide, and mix them evenly. After being ground into micron-sized fine powder in an electric grinder, mix them with the pre-activation product and load them into the activation furnace. Replace the air in the activation furnace with nitrogen at a flow rate of 500mL / min for 20min. Then, increase the temperature to 300℃ at a rate of 20℃ / min under a nitrogen flow rate of 500mL / min. Perform isothermal activation for 60min, and then increase the temperature to 750℃ at a rate of 10℃ / min. Perform isothermal activation for 80min, and then cool it to room temperature under a nitrogen atmosphere. Take out the solid activation product.

[0058] After washing with 5% dilute hydrochloric acid at a solid-liquid mass ratio of 15:1, and then washing with ultrapure water at a solid-liquid mass ratio of 40:1, the filter cake is dried in a 120℃ air-drying oven for 6h to obtain petroleum coke-based multi-level pore activated carbon. The sample scanning electron microscope image is shown in Figure 1 . The specific surface area of the obtained activated carbon is 2198m 2 / g, and the proportions of micropores, mesopores, and macropores are 75%, 12%, and 13%, respectively.

[0059] Example 2

[0060] Take 30.2g petroleum coke and 15g KOH, mix them evenly, and load them into a rotating body activation furnace. Replace the air in the activation furnace with nitrogen at a flow rate of 500mL / min for 20min. Then, pre-activate at 300℃ for 120min under a nitrogen flow rate of 500mL / min. Turn off the heating, cool it to room temperature, and take it out.

[0061] Take 3.1g petroleum pitch, 49.6g magnesium acetate, and 15.5g KOH, mix them evenly, and load them into the activation furnace after being ground into micron-sized fine powder in an electric grinder. Replace the air in the activation furnace with nitrogen at a flow rate of 500mL / min for 20min. Then, increase the temperature to 400℃ at a rate of 5℃ / min under a nitrogen flow rate of 500mL / min. Perform isothermal activation for 20min, and then increase the temperature to 900℃ at a rate of 2℃ / min. Perform isothermal activation for 20min, and then cool it to room temperature under a nitrogen atmosphere. Take out the solid activation product.

[0062] After washing with 10% dilute hydrochloric acid at a solid-liquid mass ratio of 15:1, and then washing with ultrapure water at a solid-liquid mass ratio of 40:1, the filter cake is dried in a 120℃ air-drying oven for 6h to obtain petroleum coke-based multi-level pore activated carbon. The specific surface area of the obtained activated carbon is 1128m 2 / g, and the proportions of micropores, mesopores, and macropores are 93%, 3%, and 4%, respectively.

[0063] Example 3

[0064] Take 5.1 g of petroleum coke, 25.5 g of KOH, mix uniformly, and load into the rotary activation furnace. Replace the air in the activation furnace with nitrogen at a flow rate of 500 mL / min for 20 min. Then, at a nitrogen flow rate of 500 mL / min, pre-activate at 500 ℃ for 20 min. Turn off the heating, cool to room temperature, and remove.

[0065] Take 50.2 g of petroleum pitch, 40.2 g of calcium carbonate, and 50.3 g of KOH. Grind into micron-sized fine powder in an electric grinder, and then dry mix with the pre-activation product. Load into the activation furnace. Replace the air in the activation furnace with nitrogen at a flow rate of 500 mL / min for 20 min. Then, at a nitrogen flow rate of 500 mL / min, heat to 200 ℃ at a rate of 10 ℃ / min, and then heat to 700 ℃ at a rate of 6 ℃ / min. Constant temperature activation for 100 min, and then cool to room temperature under a nitrogen atmosphere. Remove the solid activation product.

[0066] Wash with 10% mass fraction dilute hydrochloric acid at a solid-liquid mass ratio of 15:1, and then wash with ultrapure water at a solid-liquid mass ratio of 50:1. Dry the filter cake in a 120 ℃ blast drying oven for 6 h to obtain petroleum coke-based multi-level pore activated carbon. The specific surface area of the obtained activated carbon is 816 m 2 / g, and the proportions of micropores, mesopores, and macropores are 67%, 18%, and 15%, respectively.

[0067] Example 4

[0068] Take 25.2 g of petroleum coke and 50.8 g of KOH, mix uniformly, and load into the rotary activation furnace. Replace the air in the activation furnace with nitrogen at a flow rate of 500 mL / min for 20 min. Then, at a nitrogen flow rate of 500 mL / min, pre-activate at 420 ℃ for 80 min. Turn off the heating, cool to room temperature, and remove.

[0069] Take 15.1 g of isotropic mesophase pitch, 28.6 g of calcium acetate, and 45.5 g of KOH. Grind into micron-sized fine powder in an electric grinder, and then dry mix with the pre-activation product. Load into the activation furnace. Replace the air in the activation furnace with nitrogen at a flow rate of 500 mL / min for 20 min. Then, at a nitrogen flow rate of 500 mL / min, heat to 290 ℃ at a rate of 10 ℃ / min, and then heat to 800 ℃ at a rate of 5 ℃ / min. Constant temperature activation for 50 min, and then constant temperature activation for 60 min. Cool to room temperature under a nitrogen atmosphere, and remove the solid activation product.

[0070] The filter cake was washed with 10% dilute hydrochloric acid at a solid-liquid mass ratio of 20:1, and then washed with ultrapure water at a solid-liquid mass ratio of 50:1. The filter cake was dried in a blast drying oven at 120°C for 6h to obtain petroleum coke-based multi-level pore activated carbon. The specific surface area of the obtained activated carbon was 2283m 2 / g, and the proportions of micropores, mesopores and macropores were 66%, 21% and 13%, respectively.

[0071] Example 5

[0072] 20.3g of needle coke and 60.8g of KOH were weighed and uniformly mixed, and then loaded into a rotating body activation furnace. After the air in the activation furnace was replaced with nitrogen at a flow rate of 500mL / min for 20min, the nitrogen flow rate was 500mL / min, and the pre-activation was carried out at 410°C for 60min. After the heating was turned off, the solid product was taken out after cooling to room temperature.

[0073] 16.2g of anisotropic mesophase pitch, 27.5g of magnesium carbonate and 33.1g of KOH were weighed, and then ground into micron-sized fine powder in an electric grinder. The pre-activated product was dry-mixed and then loaded into the activation furnace. After the air in the activation furnace was replaced with nitrogen at a flow rate of 500mL / min for 20min, the nitrogen flow rate was 500mL / min, and the temperature was increased to 290°C at a rate of 10°C / min. The isothermal first-stage activation was carried out for 50min, and then the temperature was increased to 850°C at a rate of 5°C / min. The isothermal activation was carried out for 50min, and then the solid activated product was taken out after cooling to room temperature under a nitrogen atmosphere.

[0074] The filter cake was washed with 10% dilute hydrochloric acid at a solid-liquid mass ratio of 20:1, and then washed with ultrapure water at a solid-liquid mass ratio of 50:1. The filter cake was dried in a blast drying oven at 120°C for 6h to obtain petroleum coke-based multi-level pore activated carbon. The specific surface area of the obtained activated carbon was 2283m 2 / g, and the proportions of micropores, mesopores and macropores were 66%, 21% and 13%, respectively.

[0075] Example 6

[0076] 18.6g of petroleum coke and 46.5g of KOH were weighed and uniformly mixed, and then loaded into a rotating body activation furnace. After the air in the activation furnace was replaced with nitrogen at a flow rate of 500mL / min for 20min, the nitrogen flow rate was 500mL / min, and the pre-activation was carried out at 430°C for 60min. After the heating was turned off, the solid product was taken out after cooling to room temperature.

[0077] Take 8.4 g of calcium oxalate, 13.7 g of potassium hydroxide, and mix them in an electric grinder to form micron-sized fine powder. Then mix the fine powder with 6.8 g of catalytic cracking slurry and the pre-activated product, and load them into an activation furnace. Replace the air in the activation furnace with nitrogen at a flow rate of 500 mL / min for 20 min. Then heat the mixture to 200 ℃ at a rate of 20 ℃ / min under a nitrogen flow of 500 mL / min. Perform isothermal activation for 60 min, and then heat the mixture to 750 ℃ at a rate of 10 ℃ / min. Perform isothermal activation for 80 min, and then cool the mixture to room temperature under a nitrogen atmosphere. Take out the solid activated product.

[0078] Wash the filter cake with dilute hydrochloric acid with a mass fraction of 5% according to a solid-liquid mass ratio of 20:1, and then wash the filter cake with ultrapure water according to a solid-liquid mass ratio of 50:1. Dry the filter cake in a 120 ℃ air-drying oven for 6 h to obtain the petroleum coke-based activated carbon with multiple levels of pores. The specific surface area of the obtained activated carbon is 1607 m 2 / g, and the proportions of micropores, mesopores, and macropores are 87%, 9%, and 4%, respectively.

[0079] Example 7

[0080] Take 26.3 g of petroleum coke and 40.2 g of KOH, and mix them uniformly. Load the mixture into a rotary activation furnace. Replace the air in the activation furnace with nitrogen at a flow rate of 500 mL / min for 20 min. Then pre-activate the mixture at 420 ℃ for 60 min under a nitrogen flow of 500 mL / min. Turn off the heating, cool the mixture to room temperature, and then take out the solid activated product.

[0081] Take 17.5 g of ethylene tar, 45.5 g of magnesium acetate, and 52.5 g of potassium hydroxide, and mix them in an electric grinder to form micron-sized fine powder. Then mix the fine powder with the pre-activated product, and load them into an activation furnace. Replace the air in the activation furnace with nitrogen at a flow rate of 500 mL / min for 20 min. Then heat the mixture to 250 ℃ at a rate of 20 ℃ / min under a nitrogen flow of 500 mL / min. Perform isothermal activation for 60 min, and then heat the mixture to 900 ℃ at a rate of 10 ℃ / min. Perform isothermal activation for 40 min, and then cool the mixture to room temperature under a nitrogen atmosphere. Take out the solid activated product.

[0082] Wash the filter cake with dilute hydrochloric acid with a mass fraction of 5% according to a solid-liquid mass ratio of 20:1, and then wash the filter cake with ultrapure water according to a solid-liquid mass ratio of 50:1. Dry the filter cake in a 120 ℃ air-drying oven for 6 h to obtain the petroleum coke-based activated carbon with multiple levels of pores. The specific surface area of the obtained activated carbon is 1402 m 2 / g, and the proportions of micropores, mesopores, and macropores are 76%, 17%, and 7%, respectively.

[0083] Comparative Example 1

[0084] Take 20 g of petroleum coke, 60 g of KOH, mix evenly, put into the rotary activation furnace, replace the air in the activation furnace with nitrogen at a flow rate of 500 mL / min for 20 min, then activate at 800 ℃ for 60 min under the nitrogen flow rate of 500 mL / min, turn off the heating, cool to room temperature, and take out. The specific surface area of the obtained activated carbon is 2253 m 2 / g, the proportions of micropores, mesopores and macropores are 96%, 4% and 0%, respectively.

[0085] Comparative Example 2

[0086] Take 20 g of petroleum coke, 60 g of KOH, mix evenly, put into the rotary activation furnace, replace the air in the activation furnace with nitrogen at a flow rate of 500 mL / min for 20 min, then activate at 800 ℃ for 60 min under the nitrogen flow rate of 500 mL / min, turn off the heating, cool to room temperature, and take out. The specific surface area of the obtained activated carbon is 2253 m 2 / g, the proportions of micropores, mesopores and macropores are 96%, 4% and 0%, respectively.

[0087] Comparative Example 3

[0088] Take 20.4 g of petroleum coke, 6.8 g of petroleum pitch, 73.9 g of KOH, 5.7 g of magnesium hydroxide, and grind them into micron-sized fine powder in an electric grinder. Replace the air in the activation furnace with nitrogen at a flow rate of 500 mL / min for 20 min, then heat to 750 ℃ at a rate of 10 ℃ / min under the nitrogen flow rate of 500 mL / min, and activate at constant temperature for 80 min. Cool to room temperature under nitrogen atmosphere, and take out the solid activation product.

[0089] Wash the filter cake with 5% mass fraction of dilute hydrochloric acid at a solid-liquid mass ratio of 15:1, then wash it with ultrapure water at a solid-liquid mass ratio of 40:1. Dry the filter cake in a 120 ℃ air-drying oven for 6 h to obtain an activated carbon sample. The specific surface area of the obtained activated carbon is 1562 m 2 / g, the proportions of micropores, mesopores and macropores are 96%, 4% and 0%, respectively.

[0090] Comparative Example 4

[0091] Take 20.4 g of petroleum coke, 6.8 g of petroleum pitch, 73.9 g of KOH, and grind them into micron-sized fine powder in an electric grinder. Replace the air in the activation furnace with nitrogen at a flow rate of 500 mL / min for 20 min, then heat to 750 ℃ at a rate of 10 ℃ / min under the nitrogen flow rate of 500 mL / min, and activate at constant temperature for 80 min. Cool to room temperature under nitrogen atmosphere, and take out the solid activation product.

[0092] The obtained filter cake was washed with 5% dilute hydrochloric acid at a solid-liquid mass ratio of 15:1, and then washed with ultrapure water at a solid-liquid mass ratio of 40:1. The obtained filter cake was dried in a blast drying oven at 120℃ for 6h to obtain an activated carbon sample. The specific surface area of the obtained activated carbon was 1628m 2 / g, and the proportions of micropores, mesopores and macropores were 91%, 8% and 1% respectively.

Claims

1. A multi-level pore activated carbon, the activated carbon is a core-shell structure, comprising a core layer and a shell layer, wherein the core layer activated carbon is from a first carbon source, the first carbon source is petroleum coke, the shell layer activated carbon is from a second carbon source, the second carbon source is one or several of pitch, catalytic oil slurry, heavy hydrocarbon-containing material, the multi-level pore activated carbon has micro-pore-mesopore-macropore structure at the same time, the pore size distribution is as follows: the proportion of macropore with pore size greater than 50 nm is 5% to 30%, the proportion of mesopore with pore size of 2 to 50 nm is 10% to 70%, the proportion of micropore with pore size less than 2 nm is 40% to 80%.

2. The hierarchically porous activated carbon of claim 1, wherein, The macropore and mesopore are concentrated in the shell layer, and the micropore is concentrated in the core layer, wherein the proportion of macropore and mesopore in the shell layer is 40% to 90%, and the proportion of micropore in the core layer is 70% to 99%.

3. The hierarchically porous activated carbon of claim 1 or 2, wherein, The macropore and mesopore are concentrated in the shell layer, and the micropore is concentrated in the core layer, wherein the proportion of macropore and mesopore in the shell layer is 50% to 90%, and the proportion of micropore in the core layer is 80% to 99%.

4. The hierarchically porous activated carbon of claim 1, wherein, The specific surface area of the multi-level pore activated carbon is 400-3000 m 2 / g.

5. The hierarchically porous activated carbon of claim 1, wherein, The specific surface area of the multi-level porous activated carbon is 900-2500 m 2 / g.

6. The hierarchically porous activated carbon of claim 1, wherein, The total pore volume of the multi-level pore activated carbon is 0.3-2.5 cm 3 / g.

7. The hierarchically porous activated carbon of claim 1, wherein, The total pore volume of the multi-level pore activated carbon is 0.6-2.5 cm 3 / g.

8. The preparation method of the multi-level pore activated carbon according to any one of claims 1 to 7, comprising the following steps: (1) uniformly mixing petroleum coke and an activating agent, and then performing pre-activation treatment to obtain pre-activated petroleum coke; (2) mixing the second carbon source, an alkaline earth metal compound, the activating agent and the pre-activated petroleum coke obtained in step (1), uniformly mixing, and then performing activation treatment, and after the activation is completed, washing and drying to obtain the multi-level pore activated carbon.

9. The method of producing a hierarchically porous activated carbon according to claim 8, wherein, The activating agent in step (1) is the same as or different from the activating agent in step (2).

10. The method of making a hierarchically porous activated carbon according to claim 8, wherein, The activating agent is selected from one or several of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, calcium hydroxide and magnesium hydroxide.

11. The method of producing a hierarchically porous activated carbon according to claim 8 or 10, wherein, The activating agent is selected from one or several of sodium hydroxide, potassium hydroxide and potassium carbonate.

12. The method of preparing a hierarchically porous activated carbon according to claim 8, wherein, The volatile content of the petroleum coke raw material is between 5wt% and 20wt%.

13. The method of making a hierarchically porous activated carbon of claim 8, wherein, The weight ratio of the petroleum coke raw material to the activating agent in step (1) is 1:0.2 to 1:

10.

14. The method of producing a hierarchically porous activated carbon according to claim 8 or 13, wherein, The weight ratio of the petroleum coke raw material to the activating agent in step (1) is 1:0.5 to 1:

5.

15. The method of making a hierarchically porous activated carbon of claim 8, wherein, The pre-activation treatment in step (1) is performed in an inert atmosphere, and the inert atmosphere is one or several of nitrogen, helium, neon, argon, krypton and xenon.

16. The method of claim 8, wherein the multi-pore activated carbon is prepared by the steps of: The pre-activation temperature in step (1) is 200 to 550℃.

17. The method of claim 8 or 16, wherein the activated carbon having hierarchical pores is prepared by the method comprising: The pre-activation temperature in step (1) is 300 to 500℃.

18. The method of claim 8, wherein the multi-pore activated carbon is prepared by the steps of: The second carbon source in step (2) is one or several of pitch, catalytic oil slurry and heavy hydrocarbon-containing material.

19. The method of claim 8, wherein the multi-pore activated carbon is prepared by the steps of: The second carbon source in step (2) is pitch.

20. The method of claim 18 or 19, wherein the activated carbon having hierarchical pores is prepared by the method comprising: The pitch is one or several of petroleum pitch and coal pitch; the softening point of the petroleum pitch is 80 to 350℃, and the toluene insoluble content of the petroleum pitch is 20% to 95%.

21. The method of claim 18 or 19, wherein the activated carbon having hierarchical pores is prepared by the steps of: The pitch is petroleum pitch; the softening point of the petroleum pitch is 200 to 300℃, and the toluene insoluble content of the petroleum pitch is 50% to 80%.

22. The method of claim 18, wherein the activated carbon having hierarchical pores is prepared by the steps of: The distillation range of the heavy hydrocarbon-containing material is 350 to 700℃, and the aromatic content is 35wt% to 99wt%.

23. The method of claim 18 or 22, wherein the activated carbon having hierarchical pores is prepared by the method comprising: The distillation range of the heavy hydrocarbon-containing material is 350 to 600℃, and the aromatic content is 45wt% to 90wt%.

24. The method of claim 18 or 22, wherein the activated carbon having hierarchical pores is prepared by the method comprising: The heavy hydrocarbon-containing material is one or several of residual oil, ethylene tar, coal tar and catalytic cracking oil slurry.

25. The method of claim 18 or 22, wherein the activated carbon having hierarchical pores is prepared by the method comprising: The heavy hydrocarbon-containing material is one or more of catalytic cracking slurry oil and ethylene tar.

26. The method of making a hierarchically porous activated carbon of claim 8, wherein, The thermal decomposition temperature of the alkaline earth metal compound in step (2) is not more than 1000℃, and the decomposition temperature refers to the temperature at which the compound undergoes a chemical decomposition reaction.

27. The method of claim 8, wherein the multi-porous activated carbon is prepared by the steps of: The alkaline earth metal compound in step (2) is one or more of alkaline earth metal oxalate, alkaline earth metal carbonate, alkaline earth metal nitrate, alkaline earth metal acetate, alkaline earth metal hydroxide, and alkaline earth metal citrate.

28. The method of claim 8 or 27, wherein the activated carbon having hierarchical pores is prepared by the method comprising: The alkaline earth metal compound is selected from one or more of calcium nitrate, magnesium nitrate, strontium nitrate, calcium oxalate, magnesium oxalate, calcium carbonate, magnesium carbonate, calcium acetate, magnesium acetate, calcium citrate, magnesium citrate, calcium bicarbonate, magnesium bicarbonate, basic magnesium carbonate, and basic calcium carbonate.

29. The method of claim 8 or 27, wherein the activated carbon having hierarchical pores is prepared by the method comprising: The alkaline earth metal compound is selected from one or more of calcium nitrate, magnesium nitrate, calcium oxalate, magnesium oxalate, calcium carbonate, magnesium carbonate, calcium acetate, magnesium acetate, calcium citrate, magnesium citrate, calcium bicarbonate, magnesium bicarbonate, calcium hydroxide, and magnesium hydroxide.

30. The method of claim 8, wherein the multi-pore activated carbon is prepared by the steps of: The mass ratio of the second carbon source to the petroleum coke raw material in step (2) is 1:20 to 1:0.

1.

31. The method of claim 8 or 30, wherein the activated carbon having hierarchical pores is prepared by the method comprising: The mass ratio of the second carbon source to the petroleum coke raw material in step (2) is 1:10 to 1:0.

2.

32. The method of making a hierarchically porous activated carbon of claim 8, wherein, The mass ratio of the second carbon source to the alkaline earth metal compound in step (2) is 1:0.5 to 1:

20.

33. The method of making a hierarchically porous activated carbon of claim 8 or 32, wherein, The mass ratio of the second carbon source to the alkaline earth metal compound in step (2) is 1:0.8 to 1:

16.

34. The method of claim 8, wherein the multi-porous activated carbon is prepared by the steps of: The mass ratio of the second carbon source to the activating agent in step (2) is 1:5 to 1:0.

5.

35. The method of claim 8 or 34, wherein the activated carbon having hierarchical pores is prepared by the method comprising: The mass ratio of the second carbon source to the activating agent in step (2) is 1:3 to 1:

1.

36. The method of making a hierarchically porous activated carbon of claim 8, wherein, The activation treatment in step (2) includes two-stage activation treatment, wherein the first-stage activation treatment temperature is 80-500℃, and the second-stage activation temperature is 700-1000℃.

37. The method of claim 8 or 36, wherein the activated carbon having hierarchical pores is prepared by the method comprising: The activation treatment in step (2) includes two-stage activation treatment, wherein the first-stage activation treatment temperature is 100-400℃, and the second-stage activation temperature is 700-900℃.

38. The method of claim 8, wherein the multi-porous activated carbon is prepared by the steps of: The washing in step (2) includes acid washing and water washing.

39. The method of claim 8, wherein the activated carbon having hierarchical pores is prepared by the steps of: The drying temperature in step (2) is 60-150℃.

40. The method of claim 8 or 39, wherein the activated carbon having hierarchical pores is prepared by the method comprising: The drying temperature in step (2) is 60-120℃.

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