A graphitized mesoporous carbon support with adjustable pore size and its preparation method

Abstract

This invention discloses a graphitized mesoporous carbon support with adjustable pore size and its preparation method, belonging to the field of mesoporous carbon material preparation. The method includes the following steps: (1) adding metal acetate and magnesium salt to water and ultrasonically dispersing them to obtain a uniformly dispersed mixed solution; (2) subjecting the uniformly dispersed mixed solution to rotary evaporation and stirring to dry to obtain a solid powder mixture; (3) grinding the obtained solid powder mixture and then placing it in an inert atmosphere tube furnace for carbonization heat treatment to obtain a heat-treated product; (4) acid washing the obtained heat-treated product, then filtering and drying to obtain a graphitized mesoporous carbon support. This invention uses metal acetate as a carbon source and graphitization catalyst, and magnesium salt as a template and pore-forming agent to prepare a mesoporous carbon material support with graphitization and high specific surface area, with a pore size between 2-100 nm. Furthermore, the pore size of the mesoporous carbon can be adjusted by changing the preparation process conditions, thus achieving adjustable pore size.

Description

Technical Field

[0001] This invention relates to the field of mesoporous carbon material preparation, and more specifically to a graphitized mesoporous carbon support with adjustable pore size and its preparation method. Background Technology

[0002] Mesoporous carbon materials refer to metastable carbon crystalline nanostructures with uniform pore size and ordered or disordered arrangement. Due to their high specific surface area, abundant mesoscopic structure, uniform and tunable pore size, good chemical inertness, biocompatibility, and thermal stability, they are widely used in adsorption separation, catalysts, batteries, and capacitors. The template method is currently the most widely used and effective method for preparing mesoporous carbon. Although it can obtain micropores and mesopores with uniform size and ordered morphology, the synthetic templates used, such as mesoporous SiO2, must be dissolved in corrosive acids (HF), which not only pollutes the environment but also involves cumbersome synthesis steps and high costs. Currently, the common method for graphitizing carbon materials is to obtain graphitized carbon materials through high-temperature (>1600℃) calcination. However, this method is energy-intensive and has certain requirements for calcination equipment. While some methods can lower the calcination temperature, they often involve solvothermal treatment followed by calcination, making the synthesis steps cumbersome and often requiring corrosive solutions. Summary of the Invention

[0003] Based on the above-mentioned technical problems, this invention proposes a graphitized mesoporous carbon support with adjustable pore size and its preparation method.

[0004] The technical solution adopted in this invention is:

[0005] A method for preparing a graphitized mesoporous carbon support with adjustable pore size includes the following steps:

[0006] (1) Add metal acetate and magnesium salt to water and disperse by ultrasonication to obtain a uniformly dispersed mixed solution;

[0007] (2) The uniformly dispersed mixed solution obtained in step (1) is dried by rotary evaporation and stirring to obtain a solid powder mixture;

[0008] (3) Grind the solid powder mixture obtained in step (2) and then place it in an inert atmosphere tube furnace for carbonization heat treatment to obtain the heat-treated product;

[0009] (4) The heat-treated product obtained in step (3) is acid-washed, then filtered and dried to obtain a graphitized mesoporous carbon support.

[0010] Preferably, in step (1): the metal acetate is selected from one or more combinations of manganese acetate, iron acetate, cobalt acetate, nickel acetate, and chromium acetate; the magnesium salt is selected from one or more combinations of magnesium citrate, magnesium nitrate, magnesium chloride, magnesium acetate, and magnesium gluconate. More preferably, the metal acetate and magnesium salt are added in the form of hydrates, such as manganese acetate tetrahydrate, cobalt acetate tetrahydrate, and magnesium nitrate hexahydrate.

[0011] Preferably, in step (1), the molar ratio of the metal acetate to the magnesium salt is 1:1 to 6:1. The amount of water used for dissolution is not specifically limited; generally, when adding 0.02 to 0.03 moles of metal acetate, 10 to 20 ml of water is used to dissolve the metal acetate and magnesium salt.

[0012] Preferably, in step (1): the water used to dissolve the metal acetate and magnesium salt is warm water at 50-60°C; and the ultrasonic dispersion time is controlled to be 30-60 min.

[0013] Preferably, in step (2): the drying is controlled by rotary evaporation and stirring in a water bath at 60-70°C.

[0014] Preferably, in step (3), the inert atmosphere is one of N2 and Ar. Of course, other inert gases can also be used to provide the inert atmosphere.

[0015] Preferably, in step (3): the heat treatment temperature is controlled at 500-1000℃, more preferably 600-800℃, and the heat treatment time is 1-8h, more preferably 2-3h. During heat treatment, the heating rate is generally controlled at 2-5℃ / min.

[0016] Preferably, in step (4), the acid used for pickling is dilute sulfuric acid, dilute acetic acid or dilute hydrochloric acid, and its concentration is 0.5 to 3M.

[0017] Preferably, in step (4): the pickling temperature is controlled at 70-80℃ and the pickling time is 3-5h.

[0018] The present invention also provides a graphitized mesoporous carbon support with adjustable pore size prepared by the above method, wherein the pore size of the graphitized mesoporous carbon support is between 2 and 100 nm.

[0019] The beneficial technical effects of this invention are:

[0020] (1) The present invention uses metal acetate as carbon source and graphitization catalyst, and magnesium salt as template and pore-forming agent to prepare mesoporous carbon material carrier with graphitization and high specific surface area, with pore size between 2-100nm, and the pore size can be adjusted by changing the preparation process conditions to achieve adjustable pore size.

[0021] (2) This invention utilizes the catalytic effect of transition metals to reduce the graphitization temperature of carbon materials, resulting in a low calcination temperature and significantly reduced energy consumption. Moreover, by selecting metal acetate and magnesium salt as raw materials, the steps of solvothermal reaction are eliminated. The overall preparation method is simple, easy to operate, and can achieve adjustable pore size of mesoporous carbon, which has broad application prospects in the field of carbon carriers.

[0022] (3) When removing the template agent, the present invention can use dilute acetic acid, which has a weaker corrosiveness, compared with strong corrosive acids (such as HF), which has a smaller impact on the environment, is safer, and is easier to operate. Attached Figure Description

[0023] Figure 1 This is a scanning electron microscope (SEM) image of the graphitized mesoporous carbon support prepared in Example 1 of the present invention.

[0024] Figure 2 This is a schematic diagram of the N2 adsorption-desorption curves and pore size distribution of the graphitized mesoporous carbon support prepared in Example 1 of the present invention.

[0025] Figure 3 The image shows the X-ray diffraction (XRD) pattern of the graphitized mesoporous carbon support prepared in Example 1 of this invention.

[0026] Figure 4 The images show the Raman spectra of the graphitized mesoporous carbon supports prepared in Examples 1-6 of this invention. Detailed Implementation

[0027] This invention provides a graphitized mesoporous carbon support with adjustable pore size and its preparation method. The preparation method involves directly calcining a metal acetate and a magnesium salt, followed by acid washing to remove the template, resulting in graphitized mesoporous carbon with adjustable pore size. The method is simple and easy to operate. Specifically, this invention achieves low-temperature carbon graphitization under transition metal catalysis by heat-treating a solid mixture of metal acetate and magnesium salt. The pore size of the mesoporous carbon is controlled by adjusting the amount of magnesium salt added, etc., and then the template is removed by subsequent acid washing to prepare the graphitized mesoporous carbon support with adjustable pore size. Since magnesium salt is used as the template agent, it can be removed by acid washing with dilute acetic acid or similar substances after heat treatment, resulting in mild conditions and minimal environmental pollution.

[0028] The mesoporous carbon material prepared by this invention exhibits partial graphitization and high specific surface area, with pore sizes ranging from 2 to 100 nm, and the pore size of the mesoporous carbon material can be adjusted. The preparation method of this invention has advantages such as simple steps, ease of operation, low calcination temperature, energy saving, and environmental friendliness, significantly reducing energy consumption and equipment requirements, and facilitating market promotion and application.

[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0030] Example 1

[0031] Accurately weigh 5.88 g of manganese acetate tetrahydrate and 7.359 g of magnesium citrate nonahydrate, pour them into 12 ml of warm water at 60°C, and ultrasonically disperse for 30 min to obtain a uniformly dispersed mixed solution. Then, dry the uniformly dispersed mixed solution by rotary evaporation and stirring in a 60°C water bath to obtain a solid powder mixture. Grind the solid powder mixture into fine particles using a mortar and pestle, then place it in a porcelain boat and put it in a tube furnace filled with N2 atmosphere. Set the heating rate to 5°C / min, raise it to 800°C, and hold it for 2 h to obtain the heat-treated product. The heat-treated product is acid-washed with 0.5M dilute sulfuric acid at 80°C for 5 h, then filtered and dried to obtain a graphitized mesoporous carbon support.

[0032] Example 2

[0033] Accurately weigh 5.88 g of cobalt acetate tetrahydrate and 2.453 g of magnesium citrate nonahydrate, pour them into 12 ml of warm water at 60°C, and ultrasonically disperse for 30 min to obtain a uniformly dispersed mixed solution. Then, dry the uniformly dispersed mixed solution by rotary evaporation and stirring in a 60°C water bath to obtain a solid powder mixture. Grind the solid powder mixture into fine particles using a mortar and pestle, then place it in a porcelain boat and put it in a tube furnace filled with N2 atmosphere. Set the heating rate to 5°C / min, raise it to 600°C, and hold it for 2 h to obtain the heat-treated product. Acid wash the heat-treated product with 0.5M dilute hydrochloric acid at 80°C for 5 h, filter, and dry to obtain a graphitized mesoporous carbon support.

[0034] Example 3

[0035] Accurately weigh 5.88 g of manganese acetate tetrahydrate and 3.076 g of magnesium nitrate hexahydrate, pour them into 12 ml of warm water at 60°C, and ultrasonically disperse for 30 min to obtain a uniformly dispersed mixed solution. Then, dry the uniformly dispersed mixed solution by rotary evaporation and stirring in a 60°C water bath to obtain a solid powder mixture. Grind the dried solid powder mixture into fine particles using a mortar and pestle, then place it in a porcelain boat and put it in a tube furnace filled with Ar atmosphere. Set the heating rate to 5°C / min, raise it to 800°C, and hold it for 2 h to obtain the heat-treated product. The heat-treated product is acid-washed with 0.5M dilute sulfuric acid at 80°C for 5 h, filtered, and dried to obtain a graphitized mesoporous carbon support.

[0036] Example 4

[0037] Accurately weigh 5.88 g of nickel acetate tetrahydrate and 1.03 g of magnesium nitrate hexahydrate, pour them into 12 ml of warm water at 60°C, and ultrasonically disperse for 30 min to obtain a uniformly dispersed mixed solution. Then, dry the uniformly dispersed mixed solution by rotary evaporation and stirring in a 60°C water bath to obtain a solid powder mixture. Grind the solid powder mixture into fine particles using a mortar and pestle, then place it in a porcelain boat and put it in a tube furnace filled with N2 atmosphere. Set the heating rate to 5°C / min, raise it to 600°C, and hold it for 2 h to obtain the heat-treated product. Acid wash the heat-treated product with 0.5M dilute hydrochloric acid at 80°C for 5 h, filter, and dry to obtain a graphitized mesoporous carbon support.

[0038] Example 5

[0039] Accurately weigh 5.88 g of ferric acetate tetrahydrate and 4.98 g of magnesium gluconate, pour them into 12 ml of warm water at 50°C, and ultrasonically disperse for 60 min to obtain a uniformly dispersed mixed solution. Then, dry the uniformly dispersed mixed solution by rotary evaporation and stirring in a 70°C water bath to obtain a solid powder mixture. Grind the solid powder mixture into fine particles using a mortar and pestle, then place it in a porcelain boat and put it in a tube furnace filled with N2 atmosphere. Set the heating rate to 3°C / min, raise it to 800°C, and hold it for 3 h to obtain the heat-treated product. The heat-treated product is acid-washed with 0.5M dilute sulfuric acid at 70°C for 3 h, filtered, and dried to obtain a graphitized mesoporous carbon support.

[0040] Example 6

[0041] Accurately weigh 5.88 g of manganese acetate tetrahydrate and 1.66 g of magnesium gluconate, pour them into 12 ml of warm water at 60°C, and ultrasonically disperse for 50 min to obtain a uniformly dispersed mixed solution. Then, dry the uniformly dispersed mixed solution by rotary evaporation and stirring in a 60°C water bath to obtain a solid powder mixture. Grind the solid powder mixture into fine particles using a mortar and pestle, then place it in a porcelain boat and put it in a tube furnace filled with N2 atmosphere. Set the heating rate to 5°C / min, raise it to 700°C, and hold it for 8 h to obtain the heat-treated product. Acid wash the heat-treated product with 0.8M dilute hydrochloric acid at 80°C for 5 h, filter, and dry to obtain a graphitized mesoporous carbon support.

[0042] Comparative Example 1

[0043] The procedure is the same as in Example 1, but the carbon source is replaced with acetic acid. 5.88 g of acetic acid and 7.359 g of magnesium citrate nonahydrate were accurately weighed and poured into 12 ml of warm water at 60°C. The mixture was ultrasonically dispersed for 30 min to obtain a uniformly dispersed solution. The solution was then dried by rotary evaporation with stirring in a 60°C water bath to obtain a solid powder mixture. The solid powder mixture was ground into fine particles using a mortar and pestle, then placed in a porcelain boat and placed in a tube furnace filled with N2 atmosphere. The heating rate was set to 5°C / min, and the temperature was raised to 800°C and held for 2 h to obtain the heat-treated product. The product was then acid-washed with 0.5M dilute sulfuric acid at 80°C for 5 h, filtered, and dried to obtain the carbon material.

[0044] Comparative Example 2

[0045] The procedure is the same as in Example 1, but without the addition of a metal oxide template agent. Accurately weigh 5.88 g of manganese acetate tetrahydrate, pour it into 12 ml of warm water at 60°C, and ultrasonically disperse it for 30 min to obtain a uniformly dispersed mixed solution. Dry the solution by rotary evaporation with stirring in a 60°C water bath to obtain a solid powder mixture. Grind the solid powder mixture into fine particles using a mortar and pestle, then place it in a porcelain boat and put it in a tube furnace filled with N2 atmosphere. Set the heating rate to 5°C / min, raise the temperature to 800°C, and hold for 2 h to obtain the heat-treated product. Wash with 0.5M dilute sulfuric acid at 80°C for 5 h, filter, and dry to obtain the carbon material.

[0046] Figure 1 This is a scanning electron microscope (SEM) image of the graphitized mesoporous carbon support prepared in Example 1 of this invention. Figure 1 It can be seen that the prepared carrier is a porous nanosheet structure. Figure 2 This is a schematic diagram showing the N2 adsorption-desorption curves and pore size distribution of the graphitized mesoporous carbon support prepared in Example 1 of the present invention. Figure 2 It can be seen that the prepared graphitized mesoporous carbon support has a high specific surface area, reaching 1872 m². 2 / g, with an average pore size of 6.2nm. Figure 3 The image shown is the XRD pattern of the graphitized mesoporous carbon support prepared in Example 1 of this invention. Figure 3 The presence of graphitized carbon characteristic peaks, corresponding to the (002) crystal plane of graphite, indicates that the prepared support has a high degree of graphitization. This invention, using metal acetate as the carbon source and graphitization catalyst, and magnesium salt as the template and pore-forming agent, prepares mesoporous carbon materials with graphitization and high specific surface area. The pore size is between 2-100 nm, and the pore size can be adjusted by changing the preparation process parameters, such as the amount of magnesium salt added.

[0047] Furthermore, in Comparative Example 1, the carbon source was replaced with acetic acid, which cannot act as a graphitization catalyst. This is equivalent to the case without the addition of a transition metal graphitization catalyst, and a graphitized carbon support cannot be formed at a calcination temperature below 1600°C. Comparative Example 2 omitted the magnesium salt, meaning no metal oxide template agent was added, and ultimately, a mesoporous carbon support could not be formed either.

[0048] In summary, this invention utilizes the catalytic effect of transition metals to lower the graphitization temperature of carbon materials, resulting in a low calcination temperature and significantly reduced energy consumption. The preparation method is simple and easy to operate, and the pore size of the mesoporous carbon is adjustable, making it a promising candidate for application in the field of carbon supports.

Claims

1. A method for preparing a graphitized mesoporous carbon support with adjustable pore size, characterized in that... Includes the following steps: (1) Add metal acetate and magnesium salt to water and disperse by ultrasonication to obtain a uniformly dispersed mixed solution; (2) The uniformly dispersed mixed solution obtained in step (1) is dried by rotary evaporation with stirring to obtain a solid powder mixture; (3) Grind the solid powder mixture obtained in step (2) and then place it in an inert atmosphere tube furnace for carbonization heat treatment to obtain the heat-treated product; (4) The heat-treated product obtained in step (3) is acid-washed, then filtered and dried to obtain a graphitized mesoporous carbon support. In step (1): the metal acetate is selected from one or more combinations of manganese acetate, iron acetate, cobalt acetate, nickel acetate and chromium acetate; the magnesium salt is selected from one or more combinations of magnesium citrate, magnesium nitrate, magnesium chloride, magnesium acetate and magnesium gluconate; the water used to dissolve the metal acetate and magnesium salt is warm water at 50-60℃; the ultrasonic dispersion time is controlled to be 30-60 min. In step (2): the mixture is dried by rotary evaporation and stirring in a water bath at 60-70°C; In step (3): the inert atmosphere is either N2 or Ar; the heat treatment temperature is controlled at 600~800℃ and the heat treatment time is 1~8h.

2. The method for preparing a graphitized mesoporous carbon support with adjustable pore size according to claim 1, characterized in that, In step (1): the molar ratio of the metal acetate to the magnesium salt is 1:1 to 6:

1.

3. The method for preparing a graphitized mesoporous carbon support with adjustable pore size according to claim 1, characterized in that, In step (4): the acid used for pickling is dilute sulfuric acid, dilute acetic acid or dilute hydrochloric acid, and its concentration is 0.5~3M.

4. The method for preparing a graphitized mesoporous carbon support with adjustable pore size according to claim 1, characterized in that, In step (4): the pickling temperature is controlled at 70~80℃ and the pickling time is 3~5h.

5. The graphitized mesoporous carbon support with adjustable pore size prepared by any one of claims 1 to 4, wherein the pore size of the graphitized mesoporous carbon support is between 2 and 100 nm.

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