Petroleum coke-based multi-level pore activated carbon and preparation method thereof

Abstract

The application discloses petroleum coke-based multi-level pore activated carbon and a preparation method thereof. The preparation method comprises the following steps: firstly, pre-activating a petroleum coke raw material to obtain a pre-activated material; and then, under contact conditions, mixing an alkaline earth metal chloride, an activating agent, a carbon precursor and the pre-activated material and activating, and then washing and drying to obtain the multi-level pore activated carbon. The activated carbon comprises a core layer and a shell layer, wherein the core layer activated carbon is derived from the petroleum coke, and the shell layer activated carbon is derived from the carbon precursor, the carbon precursor is one or more of pitch, catalytic oil slurry and heavy hydrocarbon-containing material, and the multi-level pore activated carbon has a micropore-mesopore-macropore structure. The petroleum coke-based multi-level pore activated carbon has the characteristics of high specific surface and adjustable pore size distribution.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of carbon material preparation, in particular to a porous activated carbon and a preparation method thereof. BACKGROUND

[0002] With the development of modern material science, porous materials have attracted more and more attention due to their wide range of applications. Materials with micropores (pore size less than 2 nm), mesopores (pore size 2-50 nm) and macropores (pore size greater than 50 nm) can be synthesized by using amines, surfactants, block copolymers or small balls of polymers as templates. The porosity of the material endows it with new excellent properties, greatly broadening its application in exchange, separation, electrochemical processes, catalytic reaction engineering and many other aspects. Different pore structures and pore sizes of multi-level pore materials can be prepared by double-template method, single surfactant / without template agent one-step synthesis method or biological template method.

[0003] The traditional preparation method of porous carbon material is to physically or chemically activate raw materials such as coal, coconut shell and pitch, but the carbon material obtained by these methods is mainly microporous, and the pore size distribution is wide. However, in practical applications, porous carbon materials with large pore size and narrow pore size distribution are needed.

[0004] Activated carbon is prepared by pyrolysis and activation of carbon-containing raw materials such as wood, coal and petroleum coke, and has developed pore structure, large specific surface area and rich surface chemical groups. It has been successfully applied in adsorption, catalysis, double-layer capacitor electrode materials and other aspects. When activated carbon is used as a double-layer capacitor electrode material, according to the double-layer theory model, the specific capacitance of activated carbon is proportional to the specific surface area, but in fact the two do not show a linear relationship. The pore structure of the electrode material can only be fully infiltrated by the electrolyte to form a stable double layer, so compared with the specific surface area, the matching degree of the pore structure of activated carbon and the electrolyte ions is more important, so the pore structure of activated carbon needs to be adjusted according to the different electrolyte systems and application environments.

[0005] Patent CN112028074A discloses a hierarchical pore activated carbon adjustable control method and application, biomass is carbonized by hydrothermal synthesis method, then immersed in calcium chloride solution for carbon dioxide activation, which can realize the increase of the proportion of macropore 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 the hierarchical pore can be obtained, the specific surface area is sacrificed, and the preparation method is complex, and the increase of the proportion of mesopore and macropore depends on the hydrothermal synthesis process. Patent CN 110902681 A discloses a method for improving the porosity of low-quality activated carbon, which uses low-quality biomass activated carbon as raw material, and through the method of placing the low-quality activated carbon in a short-chain alkane atmosphere for pyrolysis and then in a reducing atmosphere for reduction, the low-quality activated carbon with low porosity and high micropore ratio is expanded to obtain activated carbon with high porosity, high mesopore and macropore ratio, but the limitation of this method is that 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, which uses formaldehyde and phenol as precursors to synthesize phenolic resin in the pores of activated carbon, and carbonizes at high temperature to realize the conversion of macropore and mesopore to mesopore and micropore, and further improve the specific surface area, mesopore ratio and micropore ratio of activated carbon. This method can realize the pore size repair and control 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, which uses wooden biomass as raw material, impregnates zinc chloride, then activates with KOH, and finally refines the pore structure of activated carbon by steam activation. Although the obtained activated carbon has different proportions of macropore, mesopore and micropore structure, the preparation method of activated carbon is complex, and it is only suitable for the process of preparing activated carbon from wooden biomass. SUMMARY

[0006] The existing method for controlling the pore size of activated carbon mainly starts from the carbon source such as biomass and other raw materials, and introduces an additive during the carbonization and activation process of the raw material to adjust the pore size. However, these methods cannot be well applied to the activation process of petroleum coke, petroleum pitch and other raw materials which have been highly carbonized to prepare porous activated carbon, and cannot realize further pore size control.

[0007] In view of the deficiencies of the prior art, in order to achieve the above technical purposes, the present application provides a preparation method of petroleum coke-based multi-level pore activated carbon, which mixes the product after pre-activation of petroleum coke and alkali with petroleum pitch and alkaline earth metal chloride, and then activates them together to obtain petroleum coke-based activated carbon with special radial pore distribution, which has macropore and mesopore structure as shell and micropore structure as core.

[0008] The first aspect of the present application provides a preparation method of petroleum coke-based multi-level pore activated carbon, comprising the following steps:

[0009] (1) Pre-activation treatment of petroleum coke raw material, and obtaining pre-activated material after treatment;

[0010] (2) Under contact conditions, mixing alkali earth metal chloride, activating agent, carbon precursor and pre-activated material, then activating, and then obtaining multi-level pore activated carbon through washing and drying.

[0011] In the preparation method of petroleum coke-based multi-level pore activated carbon, the pre-activation treatment of petroleum coke raw material in step (1) is as follows: under contact conditions, mixing petroleum coke raw material and activating agent, then pre-activating by heating. In general, the pre-activation temperature is 200-550°C, preferably 300-500°C; the pre-activation time is 20-150 min, preferably 40-120 min. The mass ratio of petroleum coke raw material to activating agent is 1:0.2-1:10, preferably 1:0.5-1:5. The activating agent can be one or more of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, calcium hydroxide and magnesium hydroxide, preferably one or more of sodium hydroxide, potassium hydroxide and potassium carbonate.

[0012] In the preparation method of petroleum coke-based multi-level pore activated carbon, the pre-activation treatment in step (1) is carried out under inert atmosphere, which can be one or more of nitrogen, helium, neon, argon, krypton and xenon, preferably nitrogen. Generally, before pre-activation treatment, the gas in the activating device is fully replaced with inert atmosphere to ensure that there is no oxygen in the activating device.

[0013] In the preparation method of petroleum coke-based multi-level pore activated carbon, the particle size of petroleum coke raw material in step (1) is 10-500 μm, preferably 30-300 μm; the volatile content in the petroleum coke raw material is 5wt%-20wt%.

[0014] In the preparation method of petroleum coke-based multi-level pore activated carbon, the alkali earth metal chloride in step (2) is one or more of calcium chloride, magnesium chloride, strontium chloride, beryllium chloride and barium chloride, preferably calcium chloride and / or magnesium chloride.

[0015] In the preparation method of petroleum coke-based multi-level pore activated carbon, the activating agent in step (2) is one or more of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, calcium hydroxide and magnesium hydroxide, preferably one or more of sodium hydroxide, potassium hydroxide and potassium carbonate. Further, the activating agent in step (2) is the same as or different from the activating agent for pre-activation.

[0016] In the preparation method of the petroleum coke-based multi-level pore activated carbon, the carbon source in step (2) is one or more of pitch, catalytic oil slurry, and heavy hydrocarbon-containing material, and the pitch is preferably petroleum pitch. The pitch is one or more of petroleum pitch and coal pitch, and the petroleum pitch 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 20wt%-95wt%, and is preferably 50wt%-80wt%. 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 slurry oil, and is further preferably one or more of catalytic cracking slurry oil and ethylene tar.

[0017] In the preparation method of the petroleum coke-based multi-level pore activated carbon, the weight ratio of the carbon precursor to the petroleum coke raw material in step (2) is 1:20-1:0.1, and is preferably 1:10-1:0.2.

[0018] In the preparation method of the petroleum coke-based multi-level pore activated carbon, the weight ratio of the carbon precursor to the petroleum coke raw material in step (2) is 1:20-1:0.1, and is preferably 1:10-1:0.2.

[0019] In the preparation method of the petroleum coke-based multi-level pore activated carbon, the weight ratio of the carbon precursor to the petroleum coke raw material in step (2) is 1:20-1:0.1, and is preferably 1:10-1:0.2.

[0020] In the preparation method of the petroleum coke-based multi-level pore activated carbon, when the carbon precursor, the alkaline earth metal chloride, and the activating agent are mixed with the pre-activation material in step (2), the carbon precursor, the alkaline earth metal chloride, and the activating agent are preferably mixed uniformly and pulverized to a particle size of less than 50 microns, and then mixed with the pre-activation material.

[0021] In the preparation method of the petroleum coke-based multi-level pore activated carbon, the activation in step (2) includes two-stage activation treatment. The first-stage activation treatment temperature is 80-500°C, and is preferably 100-400°C. The first-stage activation time is 20-100min, and is preferably 20-60min. The second-stage activation temperature is 700-1000°C, and is preferably 700-900°C. The second-stage activation time is 20-120min, and is preferably 20-100min.

[0022] In the preparation method of the petroleum coke-based multi-level pore activated carbon, the washing in step (2) comprises acid washing and water washing, wherein the acid washing is washing with an acid solution, the mass fraction of the acid solution is 0.5% to 20%, and preferably 1% to 10%; the mass ratio of the acid solution to the solid-phase material is 5:1 to 30:1, and preferably 5:1 to 20:1. The acid can be one or more of hydrochloric acid, nitric acid, sulfuric acid and acetic acid; the water washing is washing with deionized water or ultrapure water, and the mass ratio of water to the solid-phase material during the water washing is 10:1 to 50:1, and preferably 10:1 to 30:1.

[0023] In the preparation method of the petroleum coke-based multi-level pore activated carbon, the drying temperature in step (2) is 60 to 150°C, and preferably 60 to 120°C; and the drying time is 1 to 24 hours, and preferably 4 to 12 hours.

[0024] In the preparation method of the petroleum coke-based multi-level pore activated carbon, the alkali earth metal chloride in step (2) undergoes a double decomposition reaction with the activating agent during the mixing of the materials or the activation process, and the reaction products are uniformly distributed on the inner and outer surfaces of the carbon precursor, and play a key role in the formation of the macropores and mesopores of the activated carbon during the activation of the carbon precursor.

[0025] In the preparation method of the petroleum coke-based multi-level pore activated carbon, during the first-stage activation process, the carbon precursor exists in the form of a liquid with a certain viscosity after being heated and softened, uniformly mixes with the alkali earth metal chloride and the activating agent to uniformly wrap the pre-activation material, and forms a large number of initial forms with petroleum coke particles as cores and the carbon precursor slurry as shells.

[0026] In the preparation method of the petroleum coke-based multi-level pore activated carbon, during the second-stage activation process, the petroleum coke and the carbon precursor are simultaneously activated, the activating agent in the pre-activation material and the petroleum coke undergo radial activation reaction, 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; as the activation temperature increases, the molten activating agent (potassium hydroxide) further penetrates into the inner part of the petroleum coke pore diameter, the alkali metal vapor generated in the activation reaction travels between the carbon matrix microcrystal layers, the pore structure of the petroleum coke becomes more developed, and a certain degree of transverse pore expansion occurs, thereby realizing the conversion of the petroleum coke into the activated carbon with rich microporous structures.

[0027] In the preparation method of the petroleum coke-based multi-level pore activated carbon, in the second activation process, the volatile components in the carbon precursor are cracked or polycondensed, the uniformly wrapped alkaline earth metal chloride is decomposed in situ to generate nano-sized alkaline earth metal oxide under high temperature conditions, and the uniformly distributed in-situ polycondensed carbon is used as a template in the carbonization and activation process of the carbon precursor, while the carbon precursor, the newly generated polycondensed carbon and the activator are obviously interacted, and with the decomposition and escape of the volatile components in the carbon precursor and the alkaline earth metal chloride, abundant microporous and mesoporous structures are generated.

[0028] The second aspect of the application provides a petroleum coke-based multi-level pore activated carbon prepared by the above method, the activated carbon is in a core-shell structure, including a core layer and a shell layer, wherein the core layer activated carbon is derived from petroleum coke, and the shell layer activated carbon is derived from a carbon precursor, the carbon precursor 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%, preferably 5% to 30%; the proportion of mesopores with a pore size of 2 to 50 nm is 4% to 80%, preferably 10% to 70%; and the proportion of micropores with a pore size less than 2 nm is 10% to 95%, preferably 40% to 80%; and the macropores and mesopores are concentrated in the shell layer, and the micropores are concentrated in the core layer, wherein the proportion of macropores and mesopores in the shell layer is 40% to 90%, preferably 50% to 90%; and the proportion of micropores in the core layer is 70% to 99%, preferably 80% to 99%. In the multi-level pore activated carbon, the specific surface area of the multi-level pore activated carbon is 400 to 3000 m 2 / g, preferably 900 to 2500 m 2 / g.

[0029] In the multi-level pore activated carbon, the total pore volume of the multi-level pore activated carbon is 0.3 to 2.5 cm 3 / g, preferably 0.6 to 2.5 cm 3 / g.

[0030] Compared with the prior art, the petroleum coke-based multi-level pore activated carbon and the preparation method thereof have the following technical effects:

[0031] 1. In the preparation method of the petroleum coke-based multi-level pore activated carbon, the petroleum coke with high volatile content is used as the raw material for preparing the activated carbon, the preparation process of the activated carbon is improved for the first time from the perspective of the volatile property of the petroleum coke, and the in-situ regulation of the structure of the petroleum coke-based activated carbon is realized. In the pre-activation process, the volatile mainly composed of heavy oil is uniformly separated from the inner and outer surfaces of the petroleum coke 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 activator (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 the dehydration reaction occurs, the contact with the petroleum coke body is more and more sufficient, and a large number of active sites are introduced on the surface and inside of the raw material, laying a foundation for subsequent activation.

[0032] 2. In the preparation method of the petroleum coke-based multi-level pore activated carbon, the alkaline earth metal chloride generates the nano-sized alkaline earth metal oxide with high temperature resistance through the in-situ double decomposition reaction in the activation process, the uniform distribution of the alkaline earth metal oxide nanoparticles in the carbon precursor can be realized, the alkaline earth metal oxide nanoparticles can act as the hard template with large ionic radius, the pore size structure of the activated carbon can be adjusted by the amount of the added alkaline earth metal chloride, the pore size distribution of the petroleum coke-based activated carbon can be adjusted in-situ in the activation process, the proportion of the mesopore and macropore is appropriately increased or reduced, and the flexible regulation of the multi-level pore activated carbon on the pore structure is realized.

[0033] 3. In the preparation method of the multi-level pore activated carbon, the pre-activation, the first-stage activation and the second-stage activation are arranged in the segmented activation mode, the activation process and depth of different components are accurately regulated, different spaces are reserved for the shaping of the micropore, mesopore and macropore, the directional and flexible regulation of the pore size and proportion of the activated carbon is realized, and the problem that the petroleum coke-based activated carbon is mainly of micropore structure and has limited application is solved.

[0034] 4. The petroleum coke-based multi-level pore activated carbon has the characteristics of high specific surface and adjustable pore size distribution, has the special radial pore distribution with the macropore and mesopore structure as the shell and the micropore structure as the core on the activated carbon structure, and has a good application prospect in the fields of adsorption, catalysis, electrochemistry and the like. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The scanning electron microscope image of the sample prepared in Example 1. DETAILED DESCRIPTION

[0036] The present application is further described below in conjunction with specific embodiments, and the illustrative embodiments and descriptions of the present application are used to explain the present application, but are not used as the limitation of the present application.

[0037] Unless specifically stated otherwise, throughout the specification and claims, the term "comprising" or variations such as "comprise" or "comprises" will be understood to imply the inclusion of a stated element or group of elements but not the exclusion of any other element or group of elements.

[0038] In this document, relational terms such as "first," "second," and the like can be used solely to distinguish one entity or action from another, without necessarily implying a relationship or order between entities or actions. Such terms can include derivatives, unless context clearly indicates otherwise. Stated explicitly, such terms are not necessarily used herein as terms of limitation.

[0039] In this document, the terms "first," "second," etc. are used, inter alia, to distinguish one element from another, and are not necessarily used to describe a particular chronological or spatial order. In other words, unless explicitly stated otherwise, the terms "first," "second," etc. can be used interchangeably and are not necessarily intended to convey a chronological or spatial order.

[0040] In this document, all numerical values of parameters (e.g., of quantities or conditions) are to be interpreted in a "about" sense, regardless of whether the term "about" actually appears before the numerical value so denominated.

[0041] The specific surface area and pore size distribution curves of the sample were obtained by nitrogen adsorption-desorption curves on a Micromeritics ASAP2020 adsorption instrument, the operating temperature was -196°C (liquid nitrogen temperature), and the sample was dehydrated pretreated at 300°C under nitrogen protection before testing. The specific surface area and pore size distribution were calculated by BET method and DFT method, respectively.

[0042] The petroleum coke raw material used in the present application has the following properties: sulfur content of 4.15wt%, volatile matter of 15.79wt%, and ash content of 0.79wt%. The needle coke used is self-made in the laboratory, with a true density of 1.83g / cm 3 , volatile matter content of 8.1wt%, sulfur content of 0.2wt%, moisture content of 0.5wt%, and wide-range streamline fibrous structure.

[0043] The petroleum pitch selected in the application has a softening point of 215 DEG C, a toluene insoluble content of 56%; the anisotropic pitch has a softening point of 270 DEG C, a toluene insoluble of 74.1%, and a mesophase content of 100%; the isotropic pitch has a softening point of 265 DEG C, a toluene insoluble of 77.3%, and a mesophase content of 0%. The catalytic cracking slurry oil selected in the example of the application has a density of 1.0058 kg / m 3 , a carbon residue value of 7.1%, a carbon content of 88.4%, and a four-component composition of saturated component 32.1%, aromatic component 54.2%, resin 13.2%, and asphalt 0.5%.

[0044] The ethylene tar selected in the application has a density of 1.198 g / cm 3 at 20 DEG C, a softening point of 145 DEG C, and a carbon content of 91.81%.

[0045] Example 1

[0046] 15.6 g of petroleum coke and 45.7 g 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 with nitrogen for 20 min, the nitrogen flow rate is 500 mL / min. After pre-activation at 400 DEG C for 60 min, the heating is turned off, and the product is taken out after cooling to room temperature.

[0047] 10.4 g of petroleum pitch, 4.5 g of magnesium chloride, and 29.8 g of potassium hydroxide are weighed, and then ground into micron-sized fine powder in an electric grinder. After dry mixing with the pre-activation product, the mixture is loaded into the activation furnace. After the air in the activation furnace is replaced with nitrogen for 20 min at a flow rate of 500 mL / min, the temperature is raised to 300 DEG C at a rate of 20 DEG C / min, and then constant-temperature first-stage activation is performed for 40 min. Then, the temperature is raised to 800 DEG C at a rate of 10 DEG C / min, and constant-temperature activation is performed for 40 min. The solid activation product is taken out after cooling to room temperature under a nitrogen atmosphere.

[0048] After the filter cake is washed with 5% 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 40:1, the filter cake is dried in a 120 DEG C 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 1958 m 2 / g, and the proportions of micropores, mesopores, and macropores are 65%, 25%, and 10%, respectively.

[0049] Example 2

[0050] Take 25.6g petroleum coke, 51.5g KOH, mix evenly, put into the rotary activation furnace, replace the air in the activation furnace with nitrogen for 20min, then pre-activate at 300℃ for 120min under the nitrogen flow of 500mL / min, turn off the heating, take out after cooling to room temperature.

[0051] Take 2.6g petroleum pitch, 3.9g calcium chloride, 1.6g potassium hydroxide, grind into micron-sized fine powder in the electric grinder, dry mix with the pre-activation product, then put into the activation furnace, replace the air in the activation furnace with nitrogen at a flow rate of 500mL / min for 20min, then heat to 400℃ at a rate of 5℃ / min under the nitrogen flow of 500mL / min, constant temperature first-stage activation for 20min, then heat to 900℃ at a rate of 2℃ / min, constant temperature activation for 20min, cool to room temperature under nitrogen atmosphere, take out the solid activation product.

[0052] Wash with 5% dilute hydrochloric acid by solid-liquid mass ratio of 10:1, then wash with ultrapure water by solid-liquid mass ratio of 30:1, dry the filter cake 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 2231m 2 / g, the proportions of micropores, mesopores and macropores are 89%, 4% and 7% respectively.

[0053] Example 3

[0054] Take 5.5g petroleum coke, 27.5g KOH, mix evenly, put into the rotary activation furnace, replace the air in the activation furnace with nitrogen for 20min, then pre-activate at 500℃ for 40min under the nitrogen flow of 500mL / min, turn off the heating, take out after cooling to room temperature.

[0055] Take 27.5g petroleum pitch, 8.25g calcium chloride, 110.5g potassium hydroxide, grind into micron-sized fine powder in the electric grinder, dry mix with the pre-activation product, then put into the activation furnace, replace the air in the activation furnace with nitrogen at a flow rate of 500mL / min for 20min, then heat to 280℃ at a rate of 8℃ / min under the nitrogen flow of 500mL / min, constant temperature first-stage activation for 60min, then heat to 750℃ at a rate of 2℃ / min, constant temperature activation for 100min, cool to room temperature under nitrogen atmosphere, take out the solid activation product.

[0056] Wash with 5% dilute hydrochloric acid by solid-liquid mass ratio of 15:1, then wash with ultrapure water by solid-liquid mass ratio of 50:1, dry the filter cake 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 735m2 / g, the proportions of micropores, mesopores and macropores were 48%, 37% and 15%, respectively.

[0057] Example 4

[0058] 13.8 g of petroleum coke and 6.9 g of KOH were weighed and uniformly mixed, and then loaded into a rotary activation furnace. After the air in the activation furnace was replaced with nitrogen for 20 min at a flow rate of 500 mL / min, the pre-activation was performed at 450 ℃ for 50 min. After the heating was turned off, the product was taken out after cooling to room temperature.

[0059] 4.6 g of isotropic mesophase pitch, 3.58 g of magnesium chloride and 23.2 g of potassium hydroxide were weighed, and then ground into micron-sized fine powder in an electric grinder. After dry mixing with the pre-activation product, the mixture was loaded into the activation furnace. After the air in the activation furnace was replaced with nitrogen for 20 min at a flow rate of 500 mL / min, the temperature was raised to 310 ℃ at a rate of 7 ℃ / min, and then the isothermal first-stage activation was performed for 30 min. Then, the temperature was raised to 850 ℃ at a rate of 5 ℃ / min, and then the isothermal activation was performed for 100 min. After cooling to room temperature under a nitrogen atmosphere, the solid activation product was taken out.

[0060] After the filter cake was washed with 5% dilute hydrochloric acid according to a solid-liquid mass ratio of 10:1, and then washed with ultrapure water according to a solid-liquid mass ratio of 40:1, the filter cake was dried in a blast drying oven at 120 ℃ for 6 h to obtain the petroleum coke-based multi-level pore activated carbon. The specific surface area of the obtained activated carbon was 1026 m 2 / g, the proportions of micropores, mesopores and macropores were 76%, 15% and 9%, respectively.

[0061] Example 5

[0062] 18.7 g of needle coke and 56.2 g of KOH were weighed and uniformly mixed, and then loaded into a rotary activation furnace. After the air in the activation furnace was replaced with nitrogen for 20 min at a flow rate of 500 mL / min, the pre-activation was performed at 410 ℃ for 60 min. After the heating was turned off, the product was taken out after cooling to room temperature.

[0063] 12.5 g of anisotropic mesophase pitch, 9.77 g of calcium chloride and 37.1 g of KOH were weighed, and then ground into micron-sized fine powder in an electric grinder. After dry mixing with the pre-activation product, the mixture was loaded into the activation furnace. After the air in the activation furnace was replaced with nitrogen for 20 min at a flow rate of 500 mL / min, the temperature was raised to 290 ℃ at a rate of 10 ℃ / min, and then the isothermal first-stage activation was performed for 50 min. Then, the temperature was raised to 850 ℃ at a rate of 5 ℃ / min, and then the isothermal activation was performed for 50 min. After cooling to room temperature under a nitrogen atmosphere, the solid activation product was taken out.

[0064] After washing with 10% mass fraction dilute hydrochloric acid at a solid-liquid mass ratio of 20:1, and then washing with ultrapure water at a solid-liquid mass ratio of 50:1, the obtained filter cake is dried in a blast drying oven at 120°C for 6h to obtain the petroleum coke-based multi-level pore activated carbon. The specific surface area of the obtained activated carbon is 1734m 2 / g, and the proportions of micropores, mesopores and macropores are 69%, 17% and 14%, respectively.

[0065] Example 6

[0066] 12.8g of petroleum coke and 38.4g of KOH are mixed uniformly, and then loaded into a rotating body activation furnace. After replacing the air in the activation furnace with nitrogen for 20min, the nitrogen flow rate is 500mL / min. After pre-activation at 400°C for 50min, the heating is turned off, and the product is taken out after cooling to room temperature.

[0067] 5.1g of calcium chloride and 15.2g of potassium hydroxide are ground into micron-sized fine powder in an electric grinder, and then uniformly mixed with 7.6g of catalytic cracking slurry and the pre-activation product, and then loaded into the activation furnace. After replacing the air in the activation furnace with nitrogen for 20min at a flow rate of 500mL / min, the temperature is increased to 310°C at a rate of 7°C / min, and then constant temperature one-stage activation is performed for 30min. Then, the temperature is increased to 850°C at a rate of 5°C / min, and then constant temperature activation is performed for 100min. The solid activation product is taken out after cooling to room temperature under a nitrogen atmosphere.

[0068] After washing with 5% mass fraction dilute hydrochloric acid at a solid-liquid mass ratio of 10:1, and then washing with ultrapure water at a solid-liquid mass ratio of 50:1, the obtained filter cake is dried in a blast drying oven at 120°C for 6h to obtain the petroleum coke-based multi-level pore activated carbon. The specific surface area of the obtained activated carbon is 1336m 2 / g, and the proportions of micropores, mesopores and macropores are 82%, 15% and 3%, respectively.

[0069] Example 7

[0070] 12.8g of petroleum coke and 32.0g of KOH are mixed uniformly, and then loaded into a rotating body activation furnace. After replacing the air in the activation furnace with nitrogen for 20min, the nitrogen flow rate is 500mL / min. After pre-activation at 400°C for 50min, the heating is turned off, and the product is taken out after cooling to room temperature.

[0071] Take 12.8g of ethylene tar, 9.8g of magnesium chloride, 25.6g of KOH, and mix them evenly. After being ground into micron-sized fine powder in an electric grinder, they are mixed with the pre-activation product and loaded into an activation furnace. After replacing the air in the activation furnace with nitrogen at a flow rate of 500mL / min for 20min, the temperature is raised to 200℃ at a rate of 7℃ / min under a nitrogen flow of 500mL / min. After constant temperature activation for 30min, the temperature is raised to 900℃ at a rate of 5℃ / min. After constant temperature activation for 50min, the solid activation product is cooled to room temperature under a nitrogen atmosphere.

[0072] After washing with dilute hydrochloric acid with a mass fraction of 5% according to a solid-liquid mass ratio of 20:1, and then washing with ultrapure water with a solid-liquid mass ratio of 50:1, the filter cake is dried in a 120℃ air-drying oven for 6h to obtain a petroleum coke-based multi-level pore activated carbon. The specific surface area of the obtained activated carbon is 1665m 2 / g, and the proportions of micropores, mesopores, and macropores are 62%, 27%, and 11%, respectively.

[0073] Comparative Example 1

[0074] Take 20g of petroleum coke and 60g of KOH, mix them evenly, and load them into a rotating body activation furnace. After replacing the air in the activation furnace with nitrogen at a flow rate of 500mL / min for 20min, the temperature is raised to 800℃ at a rate of 500mL / min under a nitrogen flow. After activation for 60min, the heating is turned off, and the activated carbon is removed after cooling to room temperature. The specific surface area of the obtained activated carbon is 2253m 2 / g, and the proportions of micropores, mesopores, and macropores are 96%, 4%, and 0%, respectively.

[0075] Comparative Example 2

[0076] Take 20g of petroleum coke and 60g of KOH, mix them evenly, and load them into a rotating body activation furnace. After replacing the air in the activation furnace with nitrogen at a flow rate of 500mL / min for 20min, the temperature is raised to 800℃ at a rate of 500mL / min under a nitrogen flow. After activation for 60min, the heating is turned off, and the activated carbon is removed after cooling to room temperature. The specific surface area of the obtained activated carbon is 2253m 2 / g, and the proportions of micropores, mesopores, and macropores are 96%, 4%, and 0%, respectively.

[0077] Comparative Example 3

[0078] Take 15.6g petroleum coke, 10.4g petroleum pitch, 75.5g KOH, 4.5g magnesium chloride and mix uniformly, after being ground into micron-sized fine powder in the electric grinder, put into the activation furnace, replace the air in the activation furnace with nitrogen at a flow rate of 500mL / min for 20min, then heat to 300℃ at a rate of 20℃ / min under the nitrogen flow rate of 500mL / min, constant temperature activation for 40min, then heat to 800℃ at a rate of 10℃ / min, constant temperature activation for 40min, cool to room temperature under nitrogen atmosphere, and take out the solid activation product.

[0079] After washing with 5% mass fraction dilute hydrochloric acid according to the solid-liquid mass ratio of 20:1, and then washing with ultrapure water with 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 1668m 2 / g, and the proportions of micropores, mesopores and macropores are 81%, 15% and 4% respectively.

[0080] Comparative Example 4

[0081] Take 15.6g petroleum coke, 10.4g petroleum pitch, 75.5g KOH and mix uniformly, after being ground into micron-sized fine powder in the electric grinder, put into the activation furnace, replace the air in the activation furnace with nitrogen at a flow rate of 500mL / min for 20min, then heat to 300℃ at a rate of 20℃ / min under the nitrogen flow rate of 500mL / min, constant temperature activation for 40min, then heat to 800℃ at a rate of 10℃ / min, constant temperature activation for 40min, cool to room temperature under nitrogen atmosphere, and take out the solid activation product.

[0082] After washing with 5% mass fraction dilute hydrochloric acid according to the solid-liquid mass ratio of 20:1, and then washing with ultrapure water with 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 1668m 2 / g, and the proportions of micropores, mesopores and macropores are 81%, 15% and 4% respectively.

Claims

1. A method for preparing petroleum coke-based multi-level pore activated carbon, comprising the following steps: (1) pre-activating a petroleum coke raw material to obtain a pre-activated material; the pre-activating method is as follows: under contact conditions, the petroleum coke raw material is mixed with an activating agent, and then pre-activation is performed by heating; (2) under the contacting condition, mixing the alkaline earth metal chloride, the activating agent, the carbon precursor, and the pre-activated material, then activating, and then washing and drying to obtain the hierarchical porous activated carbon; wherein, the carbon precursor is one or more of pitch, catalytic oil slurry, and heavy hydrocarbon-containing material; the activation comprises two-stage activation, wherein the first-stage activation temperature is 80-500°C, and the second-stage activation temperature is 700-1000°C.

2. The method of claim 1, wherein the petroleum coke-based activated carbon having multiple levels of pores is prepared by the steps of: The pre-activation temperature in step (1) is 200-550°C.

3. The method of claim 1, wherein the petroleum coke-based activated carbon having multiple levels of pores is prepared by the steps of: The pre-activation temperature in step (1) is 300-500°C.

4. The method of claim 1, wherein the petroleum coke-based activated carbon having multiple levels of pores is prepared by the steps of: The mass ratio of the petroleum coke raw material to the activating agent is 1:0.2-1:

10.

5. The method of claim 1 or 4, wherein the petroleum coke-based activated carbon having a plurality of levels of pores is prepared by the steps of: The mass ratio of the petroleum coke raw material to the activating agent is 1:0.5-1:

5.

6. The method of claim 1, wherein the petroleum coke-based activated carbon having multiple levels of pores is prepared by the steps of: The activating agent in step (1) is one or more of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, calcium hydroxide, and magnesium hydroxide.

7. The method of claim 1 or 6, wherein the petroleum coke-based activated carbon having a plurality of levels of pores is prepared by the steps of: The activating agent in step (1) is one or more of sodium hydroxide, potassium hydroxide, and potassium carbonate.

8. The method of claim 1, wherein the petroleum coke-based activated carbon having multiple levels of pores is prepared by the steps of: The pre-activation in step (1) is performed under an inert atmosphere selected from one or more of nitrogen, helium, neon, argon, krypton, and xenon.

9. The method of claim 1, wherein the petroleum coke-based activated carbon having multiple levels of pores is prepared by the steps of: The petroleum coke raw material in step (1) has a particle size of 10-500 μm; and the volatile content of the petroleum coke raw material is 5wt%-20wt%.

10. The method of claim 1 or 9, wherein the petroleum coke-based activated carbon having a plurality of levels of pores is prepared by the steps of: The petroleum coke raw material in step (1) has a particle size of 30-300 μm.

11. The method of claim 1, wherein the petroleum coke-based activated carbon having multiple levels of pores is prepared by the steps of: The alkaline earth metal chloride in step (2) is one or more of calcium chloride, magnesium chloride, strontium chloride, beryllium chloride, and barium chloride.

12. The method of claim 1 or 11, wherein the petroleum coke-based, hierarchically porous activated carbon is prepared by the method comprising: The alkaline earth metal chloride in step (2) is calcium chloride and / or magnesium chloride.

13. The method of claim 1, wherein the petroleum coke-based activated carbon having multiple levels of pores is prepared by the steps of: The activating agent in step (2) is one or more of sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, calcium hydroxide, and magnesium hydroxide.

14. The method of claim 1 or 13, wherein the petroleum coke-based activated carbon having a plurality of levels of pores is prepared by the steps of: The activating agent in step (2) is one or more of sodium hydroxide, potassium hydroxide, and potassium carbonate.

15. The process for preparing petroleum coke based activated carbon having hierarchical porosity as claimed in claim 1 wherein, The carbon precursor in step (2) is pitch.

16. The method of claim 15, wherein the petroleum coke-based, hierarchically porous activated carbon is prepared by: The pitch is one or more of petroleum pitch and coal pitch; the petroleum pitch has a softening point of 80-350°C and a toluene insoluble content of 20wt%-95wt%.

17. The method of claim 15, wherein the petroleum coke-based, hierarchically porous activated carbon is prepared by: The pitch is petroleum pitch; the petroleum pitch has a softening point of 200-300°C and a toluene insoluble content of 50wt%-80wt%.

18. The method of claim 1, wherein the petroleum coke-based activated carbon having multiple levels of pores is prepared by the steps of: The heavy hydrocarbon-containing material has a distillation range of 350-700°C and an aromatic content of 35wt%-99wt%.

19. The method of claim 15 or 18, wherein the petroleum coke-based hierarchical porous activated carbon is prepared by the steps of: The heavy hydrocarbon-containing material has a distillation range of 350-600°C and an aromatic content of 45wt%-90wt%.

20. The method of claim 15, wherein the petroleum coke-based, hierarchically porous activated carbon is prepared by: The heavy hydrocarbon-containing material is one or more of residual oil, ethylene tar, coal tar, and catalytic cracking slurry oil.

21. The method of claim 15 or 20, wherein the petroleum coke-based hierarchical porous activated carbon is prepared by the steps of: The heavy hydrocarbon-containing material is one or more of catalytic cracking slurry oil and ethylene tar.

22. The method of claim 1, wherein the petroleum coke-based activated carbon having multiple levels of pores is prepared by the steps of: The weight ratio of the carbon precursor to the petroleum coke raw material in step (2) is 1:20-1:0.

1.

23. The method of claim 1 or 22, wherein the petroleum coke-based, hierarchically porous activated carbon is prepared by: The weight ratio of the carbon precursor to the petroleum coke raw material in step (2) is 1:10-1:0.

2.

24. The method of claim 1, wherein the petroleum coke-based activated carbon having multiple levels of pores is prepared by the steps of: The weight ratio of the carbon precursor to the alkaline earth metal chloride in step (2) is 1:2-1:0.

1.

25. The method of claim 1 or 24, wherein the petroleum coke-based, hierarchically porous activated carbon is prepared by: The weight ratio of the carbon precursor to the alkaline earth metal chloride in step (2) is 1:1.5-1:0.

3.

26. The process for preparing petroleum coke based activated carbon having hierarchical porosity according to claim 1, wherein, The weight ratio of the carbon precursor to the activating agent in step (2) is 1:6-1:0.

5.

27. The method of claim 1 or 26, wherein the petroleum coke-based, hierarchically porous activated carbon is prepared by: The weight ratio of the carbon precursor to the activating agent in step (2) is 1:5-1:0.

6.

28. The process for preparing petroleum coke based activated carbon having hierarchical porosity according to claim 1, wherein, The activation in step (2) includes two-stage activation, wherein the first-stage activation temperature is 100-400℃, and the second-stage activation temperature is 700-900℃.

29. The process for preparing petroleum coke based activated carbon having hierarchical porosity as claimed in claim 1 wherein, The washing in step (2) includes acid washing and water washing, and the acid washing is performed using an acid solution, and the acid is one or more of hydrochloric acid, nitric acid, sulfuric acid, and acetic acid.

30. The process for preparing petroleum coke based activated carbon having hierarchical porosity according to claim 1, wherein, The drying temperature in step (2) is 60-150℃.

31. The process for preparing petroleum coke based activated carbon having hierarchical porosity according to claim 1, wherein, The drying temperature in step (2) is 60-120℃.

32. A petroleum coke-based hierarchical porous activated carbon obtained by the method of any one of claims 1-31.

33. The petroleum coke-based hierarchical porous activated carbon of claim 32, wherein, The activated carbon has a core-shell structure, including a core layer and a shell layer, wherein the core layer activated carbon is derived from petroleum coke, and the shell layer activated carbon is derived from a carbon precursor, and the carbon precursor is one or more of pitch, catalytic oil slurry, and heavy hydrocarbon-containing material, and the hierarchical porous 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%-35%, the proportion of mesopores with a pore size of 2-50 nm is 4%-80%, and the proportion of micropores with a pore size less than 2 nm is 10%-95%.

34. The petroleum coke-based hierarchical porous activated carbon of claim 33, wherein, The hierarchical porous 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 5%-30%, the proportion of mesopores with a pore size of 2-50 nm is 10%-70%, and the proportion of micropores with a pore size less than 2 nm is 40%-80%.

35. The petroleum coke-based hierarchical porous activated carbon of claim 33 or 34, wherein, The macropores and mesopores are concentrated in the shell layer, and the micropores are concentrated in the core layer, wherein the proportion of macropores and mesopores in the shell layer is 40%-90%, and the proportion of micropores in the core layer is 70%-99%.

36. The petroleum coke-based hierarchical porous activated carbon of claim 33 or 34, wherein, The macropores and mesopores are concentrated in the shell layer, and the micropores are concentrated in the core layer, wherein the proportion of macropores and mesopores in the shell layer is 50%-90%, and the proportion of micropores in the core layer is 80%-99%.

37. The petroleum coke-based hierarchical porous activated carbon of claim 32, wherein, The specific surface area of the multi-level pore activated carbon is 400-3000 m 2 / g.

38. The petroleum coke-based hierarchical porous activated carbon of claim 32 or 37, wherein, The specific surface area of the multi-level porous activated carbon is 900-2500 m 2 / g.

39. The petroleum coke-based hierarchical porous activated carbon of claim 32, wherein, The total pore volume of the multi-level pore activated carbon is 0.3-2.5 cm 3 / g.

40. The petroleum coke-based hierarchical porous activated carbon of claim 32 or 39, wherein, The total pore volume of the multi-level pore activated carbon is 0.6-2.5 cm 3 / g.

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