A regular spherical flower-like porous carbon material and a preparation method and application thereof

Abstract

The present application relates to the technical field of porous carbon material preparation, and particularly relates to a regular spherical flower-like porous carbon material, a preparation method and application thereof. A suspension formed by mixing a carbonate solution and a magnesium salt solution is subjected to aging treatment to obtain a reaction solution; the reaction solution and a carbon precursor are mixed and subjected to hydrothermal treatment to obtain brown powder; the brown powder is calcined under an inert gas atmosphere to obtain black powder; and the black powder is subjected to acid pickling to obtain the regular spherical flower-like porous carbon material. The present application successfully synthesizes a regular spherical flower-like porous carbon material by using biomass as a carbon source and adopting a method of combining aging pretreatment with hydrothermal carbonization. A Pd(OH)2 / C catalyst prepared by using the material as a carrier shows excellent catalytic activity in a hydrogenolysis debenzyl reaction of a cage substrate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of porous carbon material preparation, and particularly relates to a regular spherical flower-like porous carbon material and a preparation method and application thereof. BACKGROUND

[0002] Porous carbon material has large specific surface area, good electrical conductivity, rich pore size and three-dimensional hierarchical structure, which makes the porous carbon material have great prospects in the fields of catalysis, electrochemical energy storage and gas adsorption. The preparation process of the porous carbon material usually comprises chemical activation (ZnCl2, H3PO4, KOH activation of carbon raw material) and physical activation (CO2 and steam activation of carbon raw material), and the pore structure and morphology of the carbon material obtained by different activation methods are not easy to control, and strong corrosive reagents or high-temperature treatment process are needed. Since the properties of the carbon material are closely related to the structure of the carbon precursor, in order to adjust the performance of the carbon material, various precursors with special structures are used to prepare functional carbon materials, such as ionic liquid, graphene, covalent organic framework material and organic polymer.

[0003] The template method is a conventional method for preparing the porous carbon material, and is divided into a soft template method and a hard template method. The soft template method is usually to form an ordered template by aggregation of surfactant molecules, to form a precursor with ordered pore structure by self-assembly through the interaction between the carbon source and the template agent, and to obtain mesoporous carbon material by high-temperature treatment. The hard template method is to introduce an organic precursor solution into a mesoporous material as a template, so that the template pores or interstices are filled, and then to obtain mesoporous carbon material similar to the pore structure of the hard template by high-temperature calcination and template removal. Common hard templates include silica, mesoporous silica and molecular sieve. The hard template method can synthesize carbon material with uniform pore size, large specific surface area and ordered pore structure. However, the template synthesis process is relatively complex and cumbersome, the utilization efficiency of the template is not high, and strong corrosive reagents such as HF and NaOH are needed. Therefore, it is of great significance to develop an efficient and environmentally friendly preparation method for porous carbon nanomaterials. SUMMARY

[0004] The present application aims to provide a regular spherical flower-like porous carbon material and a preparation method and application thereof, so as to solve the problems in the prior art.

[0005] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0006] The present application provides a preparation method of a regular spherical flower-like porous carbon material, comprising the following steps:

[0007] Step 1) aging treatment is performed on the suspension formed by mixing the carbonate solution and the magnesium salt solution to obtain a reaction solution;

[0008] Step 2) mixing the reaction solution and the carbon precursor and then performing hydrothermal treatment to obtain brown powder;

[0009] Step 3) performing calcination on the brown powder in an inert gas atmosphere to obtain black powder;

[0010] Step 4) performing acid washing on the black powder to obtain regular spherical flower-like porous carbon material.

[0011] Preferably, the carbonate comprises one or more of sodium carbonate, potassium carbonate and ammonium carbonate; and the magnesium salt comprises one or more of magnesium nitrate, magnesium chloride and magnesium sulfate.

[0012] Preferably, the concentration of the carbonate solution is 0.106 g / mL; the concentration of the magnesium salt solution is 0.203 g / mL; and the mass ratio of the magnesium salt to the carbonate is 8.12:5.3.

[0013] Preferably, the temperature of the aging treatment is 60-100℃, and the time is 1-10 h.

[0014] Preferably, the mass ratio of the magnesium salt to the carbon precursor is 1:0.4-1; and the carbon precursor comprises one or more of glucose, fructose, sucrose, starch and cellulose.

[0015] Preferably, the temperature of the hydrothermal treatment is 160-220℃, and the time is 18-24 h.

[0016] Preferably, the inert gas comprises one or more of nitrogen, helium and argon; the temperature of the calcination is 600-1200℃, and the time is 2-4 h.

[0017] Preferably, the acid washing is stirring the black powder in a dilute hydrochloric acid solution and then washing with water; the concentration of the dilute hydrochloric acid is 20 wt%; and the stirring time is 4-10 h.

[0018] The application also provides the regular spherical flower-like porous carbon material prepared by the above preparation method, wherein the diameter of the porous carbon material is 5-50 μm, each carbon sphere is formed by ordered stacking of multiple carbon nanosheets, and the porous carbon material has abundant mesoporous and macroporous structures.

[0019] The application also provides the application of the Pd(OH)2 / C catalyst prepared by using the above regular spherical flower-like porous carbon material as a carrier in hydrogenolysis debenzylization.

[0020] Compared with the prior art, the application has the following beneficial effects:

[0021] In the technical solution of the present application, the water-soluble magnesium salt and the water-soluble carbonate are aged under controllable conditions to form a template with regular morphology, and then a carbon precursor is added to the reaction system for hydrothermal carbonization, so that the template synthesis and the hydrothermal carbonization of the organic carbon precursor are carried out in the same system, greatly simplifying the operation process. Moreover, the residual template after calcination can be completely removed with dilute hydrochloric acid, avoiding the use of strong corrosive reagents such as HF, KOH or NaOH. The method is simple in operation, stable in process, and the product has regular and easy-to-control morphology.

[0022] The present application successfully synthesizes a regular spherical flower-like porous carbon material by using biomass as a carbon source and adopting an aging pretreatment and hydrothermal carbonization method. The Pd(OH)2 / C catalyst prepared by using the material as a carrier shows excellent catalytic activity in the hydrogenolysis debenzylization reaction of a cage substrate. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 X-ray diffraction pattern of the white solid obtained after aging the magnesium chloride solution and the sodium carbonate solution in Example 1;

[0024] Figure 2 X-ray diffraction pattern of the white solid directly generated at room temperature after mixing the magnesium chloride solution and the sodium carbonate solution in Comparative Example 1;

[0025] Figure 3 Scanning electron microscope (SEM) image of the white solid obtained after aging the magnesium chloride solution and the sodium carbonate solution in Example 1;

[0026] Figure 4 Scanning electron microscope (SEM) image of the white solid directly generated at room temperature after mixing the magnesium chloride solution and the sodium carbonate solution in Comparative Example 1;

[0027] Figure 5 X-ray diffraction pattern of the hydrothermal product 1# sample (hydrothermal product) prepared in Example 1;

[0028] Figure 6 X-ray diffraction pattern (a) and scanning electron microscope (SEM) image (b) of the hydrothermal product 3# sample prepared in Comparative Example 1;

[0029] Figure 7 Scanning electron microscope (SEM) images of the regular spherical flower-like porous carbon materials 1-1# (a) and 2-1# (b) prepared in Example 1 and Example 2;

[0030] Figure 8 Hydrogen absorption curve of the Pd(OH)2 / C catalyst prepared by using the regular spherical flower-like porous carbon materials 2-1# and 3-1# as carriers and commercial activated carbon as a control carrier in the TADB hydrogenolysis debenzylization reaction. DETAILED DESCRIPTION

[0031] The technical solutions provided by the present application are described in detail below in conjunction with examples, but they should not be understood as limiting the scope of protection of the present application.

[0032] Example 1

[0033] 8.12 g of magnesium chloride was weighed into 40 ml of deionized water, 5.3 g of sodium carbonate was dissolved in 50 ml of deionized water, the sodium carbonate solution was slowly added to the magnesium chloride solution and stirred for 30 min to form a suspension, the suspension was transferred to a water bath, and the system was aged at 80℃ for 2 h. After completion, 3.6 g of glucose was added to the system and stirred for 30 min, the suspension was transferred to a polytetrafluoroethylene liner, and the liner was loaded into a stainless steel autoclave for reaction at 180℃ for 24 h. The brown solid was filtered and recorded as a 1# sample. The 2# sample was placed in a tube furnace and calcined at 700℃ for 2 h under a nitrogen atmosphere. After cooling to room temperature, the obtained black powder was added to a 20 wt% dilute hydrochloric acid solution, stirred for 4 h to remove the template, washed with deionized water, and dried to obtain a regular spherical flower-like porous carbon material, recorded as a 1-1# sample.

[0034] The scanning electron microscope image of the 1-1# sample is shown in Figure 7 (a), and it can be seen from Figure 7 (a) that the regular spherical flower-like porous carbon material is successfully prepared.

[0035] Example 2

[0036] 8.12 g of magnesium chloride was weighed into 40 ml of deionized water, 5.3 g of sodium carbonate was dissolved in 50 ml of deionized water, the sodium carbonate solution was slowly added to the magnesium chloride solution and stirred for 30 min to form a suspension, the suspension was transferred to a water bath, and the system was aged at 80℃ for 2 h. After completion, 3.6 g of glucose was added to the system and stirred for 30 min, the suspension was transferred to a polytetrafluoroethylene liner, and the liner was loaded into a stainless steel autoclave for reaction at 180℃ for 24 h. The brown solid was filtered and recorded as a 1# sample. The 2# sample was placed in a tube furnace and calcined at 700℃ for 2 h under a nitrogen atmosphere. After cooling to room temperature, the obtained black powder was added to a 20 wt% dilute hydrochloric acid solution, stirred for 4 h to remove the template, washed with deionized water, and dried to obtain a regular spherical flower-like porous carbon material, recorded as a 1-1# sample.

[0037] The scanning electron microscope image of the 2-1# sample is shown in Figure 7 (b), and it can be seen from Figure 7 (b) that the regular spherical flower-like porous carbon material is successfully prepared.

[0038] Comparative Example 1

[0039] 8.12 g of magnesium chloride was dissolved in 40 ml of deionized water, and 5.3 g of sodium carbonate was dissolved in 50 ml of deionized water. The sodium carbonate solution was slowly added to the magnesium chloride solution and stirred for 30 min to form a suspension. 3.6 g of glucose was added, and stirring was continued for 30 min. The suspension was transferred to a polytetrafluoroethylene (PTFE) liner, and the liner was placed in a stainless steel autoclave. The reaction was carried out at 180 °C for 24 h. The brown solid sample #3 was obtained by filtration.

[0040] When water-soluble carbonates and water-soluble magnesium salts are added to an appropriate amount of deionized water, magnesium carbonate trihydrate is mainly formed at room temperature. Figure 2 , Figure 4 Its morphology is mainly rod-shaped. Under subsequent hydrothermal conditions, magnesium carbonate trihydrate is mainly converted into magnesium carbonate, with only a small portion of basic magnesium carbonate forming. Therefore, the resulting hydrothermal carbon material has an irregular morphology. Figure 6 By aging a suspension of water-soluble carbonates and water-soluble magnesium salts under certain conditions, regular spherical flower-shaped basic magnesium carbonate can be obtained. Figure 1 , Figure 3 Under hydrothermal conditions, basic magnesium carbonate can still maintain a regular morphology and crystal phase. Figure 5 This is the key to the present invention.

[0041] Application examples

[0042] Using the regular spherical flower-like porous carbon materials 1-1# and 2-1# obtained in Examples 1 and 2 as supports, and commercial activated carbon from ACROS Organics as a control support, corresponding Pd(OH)2 / C catalysts (Pd / C-1-1#, Pd / C-2-1#, and palladium catalyst supported on commercial activated carbon) were prepared by deposition-precipitation method. The catalytic activity was evaluated using the hydrogenodebenzylation reaction of TADB as a probe. The reaction conditions were as follows: TADB 20g, catalyst 1.03g, CH3COOH 80ml, H2O 20ml, and perchloric acid 0.5ml. After the addition of materials, hydrogen was purged three times, stirring was started, and the reaction was carried out at 43°C for 12h. The hydrogen absorption curves of the catalyst samples prepared in the two examples and the commercial palladium catalyst supported on activated carbon are shown in the appendix. Figure 8 ,Depend on Figure 8 It can be seen that, compared with commercial activated carbon supported catalysts, the 1-1# and 2-1# catalysts prepared in the examples have a fast hydrogen absorption rate and a large amount of hydrogen absorption in the hydrogen debenzylation reaction of TADB, exhibiting excellent catalytic activity.

[0043] From the above examples, the application provides a kind of regular spherical flower-like porous carbon material and its preparation method and application.The present application uses biomass as carbon source, adopts the method of aging pretreatment and hydrothermal carbonization organic combination, and successfully synthesizes a kind of regular spherical flower-like porous carbon material.The Pd (OH) 2 / C catalyst prepared by using the material as carrier shows excellent catalytic activity in the hydrogenolysis debenzyl reaction of cage substrate.

[0044] The above only is the preferred embodiment of the present application, it should be pointed out, for the ordinary skilled in the art, without departing from the principles of the present application, can also make a number of improvements and refinements, these improvements and refinements should also be considered the protection scope of the present application.

Claims

1. A method for preparing a regular spherical flower-like porous carbon material, characterized in that, Includes the following steps: Step 1) The suspension formed by mixing the carbonate solution and the magnesium salt solution is aged to obtain the reaction solution; Step 2) The reaction solution and carbon precursor are mixed and then subjected to hydrothermal treatment to obtain a brown powder; Step 3) The brown powder is calcined in an inert gas atmosphere to obtain a black powder; Step 4) The black powder is acid-washed to obtain a regular spherical flower-shaped porous carbon material; The concentration of the carbonate solution is 0.106 g / mL; the concentration of the magnesium salt solution is 0.203 g / mL; the mass ratio of magnesium salt to carbonate is 8.12:5.

3. The aging treatment is performed at a temperature of 60–100°C for a time of 1–10 hours. The mass ratio of the magnesium salt to the carbon precursor is 1:0.4 to 1; the carbon precursor comprises one or more of glucose, fructose, sucrose, starch, and cellulose. The hydrothermal treatment is performed at a temperature of 160–220°C for a duration of 18–24 hours. The inert gas includes one or more of nitrogen, helium, and argon; the calcination temperature is 600–1200°C, and the time is 2–4 hours.

2. The method for preparing a regular spherical flower-like porous carbon material according to claim 1, characterized in that, The carbonate comprises one or more of sodium carbonate, potassium carbonate, and ammonium carbonate; the magnesium salt comprises one or more of magnesium nitrate, magnesium chloride, and magnesium sulfate.

3. The method for preparing a regular spherical flower-like porous carbon material according to claim 1, characterized in that, The pickling process involves adding the black powder to a dilute hydrochloric acid solution, stirring, and then washing with water; the concentration of the dilute hydrochloric acid is 20 wt%; and the stirring time is 4–10 h.

4. A regular spherical flower-like porous carbon material prepared by the preparation method according to any one of claims 1 to 3, characterized in that, The diameter of the porous carbon material is 5 to 50 μm. Each carbon sphere is composed of multiple carbon nanosheets stacked in an orderly manner, and has a rich mesoporous and macroporous structure.

5. The application of a Pd(OH)2 / C catalyst prepared using the regular spherical flower-like porous carbon material as described in claim 4 as a support in the dehydrobenzyl hydrolysis.

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