High-crosslinking-degree COPNA resin as well as preparation method and application thereof

Abstract

The invention discloses high-crosslinking-degree COPNA resin, a preparation method and application, and the preparation method comprises the following steps: dispersing aromatic hydrocarbon-rich heavy organic components in a certain amount of solvent in a reaction kettle, and adding a catalyst and a crosslinking agent; carrying out pre-crosslinking reaction under the condition of normal pressure, after the pre-crosslinking reaction is completed, raising the temperature, carrying out deep crosslinking reaction while evaporating to remove the solvent, and mashing and discharging a deep crosslinking solid product; or carrying out pressurized cross-linking reaction under a certain temperature condition, and after the reaction is finished, filtering and separating a solid product. The crosslinking degree and heat resistance of the COPNA resin are effectively improved, meanwhile, the problem that mass transfer is not uniform in the reaction process is solved, and the obtained product is a hard carbon material after being pre-oxidized and carbonized.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of COPNA resins, and in particular to a COPNA resin with a high degree of crosslinking, a preparation method and an application. Background Art

[0002] COPNA resin (Condensed Polynuclear Aromatic Resin) is a high-performance thermosetting resin formed by the condensation reaction of polycyclic aromatic hydrocarbons. Due to its excellent heat resistance, mechanical properties and chemical stability, COPNA resin has a wide range of applications in the fields of carbon material binders, composite materials, new carbon materials, etc. The degree of condensation of COPNA resin refers to the density of the three-dimensional network structure formed by the chemical bond connection between resin molecular chains. COPNA resins can be divided into three types according to the degree of condensation: A-stage COPNA resin (lower degree of condensation, liquid at room temperature); B-stage COPNA resin (higher degree of condensation, solid at room temperature but can be melted at higher temperatures and soluble in common organic solvents); C-stage COPNA resin obtained by curing B-stage COPNA resin has the highest degree of condensation, is a high-temperature hardening product and does not melt when heated and is insoluble in organic solvents.

[0003] The structure and properties of COPNA resin-derived carbon materials largely depend on the crosslinking degree of the precursor resin, which directly affects the microcrystalline structure, pore structure, graphitization degree and electrochemical properties of the carbon materials. Usually, COPNA resin is cured-carbonized to obtain soft carbon materials. Even if the amount of crosslinking agent is increased and its d 002 value increases, it still cannot meet the requirements of hard carbon materials (>0.37 nm)

Otani S, Yu Hongan, Ota E. Carbonization behavior of condensed polynuclear aromatic (COPNA) resins. Tanso, 1986, 127(1): 162-170.

Xiao Zhiying, Jiang Jianchun, etc. Orthogonal method to select the optimal synthesis conditions of COPNA resin. Carbon, 2006, (1): 27-31.

[0004] In view of the above analysis, the present invention aims to provide a method for synthesizing a highly crosslinked COPNA resin and its application, which avoids the phenomenon that the synthesis reaction of the highly crosslinked COPNA resin is inhibited due to the system viscosity, and can omit the curing step of preparing the highly crosslinked COPNA resin from the B-stage COPNA resin.

[0005] The main object of the present invention is achieved by the following technical solutions:

[0006] A method for preparing a highly crosslinked COPNA resin, the specific process is as follows:

[0007] (1) Dispersing the heavy aromatic organic components in a solvent in a reaction kettle, and adding a catalyst and a crosslinking agent;

[0008] (2) The mixed system in step (1) is subjected to a pre-crosslinking reaction under normal pressure conditions. After the pre-crosslinking reaction is completed, the temperature is raised to carry out a deep crosslinking reaction while evaporating the solvent. The deep crosslinked solid product is mashed to obtain a highly crosslinked COPNA resin;

[0009] Or;

[0010] The mixed system in step (1) is subjected to a pressure crosslinking reaction. After the pressure crosslinking reaction is completed, the solid product is separated by filtration to obtain a highly crosslinked COPNA resin.

[0011] Furthermore, the heavy aromatic organic components are coal tar, ethylene tar, coal pitch, petroleum pitch or coal liquefaction pitch; the solvent is tetrahydrofuran (THF), dioxane, dimethylformamide (DMF) or N-methylpyrrolidone (NMP); the catalyst is sulfuric acid, benzenesulfonic acid or p-toluenesulfonic acid; the crosslinking agent is trioxane, paraformaldehyde, benzaldehyde, furfural, p-xylene glycol or dimethoxymethane.

[0012] Furthermore, the mass ratio of the heavy aromatic organic components, the crosslinking agent, the catalyst and the solvent is: 100:10 - 300:3 - 50:50 - 500.

[0013] Furthermore, the temperature of the pre-crosslinking reaction is 50 - 150 °C, and the reaction time is 6 - 12 h.

[0014] Furthermore, the temperature of the deep crosslinking reaction is 120 - 240 °C until the sample in the reaction kettle becomes solid and the reaction ends.

[0015] Furthermore, the temperature of the pressure crosslinking reaction is 120 - 250 °C, the pressure of the pressure crosslinking reaction is 0.5 - 15 MPa, and the pressure crosslinking reaction time is 12 - 48 h.

[0016] Application of the highly crosslinked COPNA resin prepared by the above method, specifically applied to the preparation of a hard carbon material based on the highly crosslinked COPNA resin. Specifically: the highly crosslinked COPNA resin is pre-oxidized at 250-350 °C for 3-9 h in an air atmosphere, and carbonized at 1100-1500 °C for 1-3 h in an inert atmosphere to obtain a hard carbon material based on the highly crosslinked COPNA resin.

[0017] The beneficial effects of the present invention are as follows:

[0018] 1) The present invention provides a method for preparing a highly crosslinked COPNA resin. The two-step synthesis method or the pressure synthesis method used can effectively improve the crosslinking degree and heat resistance of the COPNA resin while solving the problem of uneven mass transfer during the reaction process, and its gel content can reach 80%.

[0019] 2) The obtained highly crosslinked COPNA resin only needs simple pre-oxidation to effectively inhibit the inherent graphitization tendency of the COPNA resin prepared by the traditional method during high-temperature carbonization. The interlayer spacing of the carbonized hard carbon material > 0.38 nm. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 XRD patterns of the COPNA resin-derived carbon prepared in Example 1, Example 4, Example 7, and Example 8.

[0021] Figure 2 XRD pattern of the COPNA resin-derived carbon prepared in the comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0022] The present invention will be further described below in combination with examples and comparative examples. Among them, Examples 1 to 10 are all test methods of the present invention, and the comparative example is a comparative experiment on the synthesis of traditional COPNA resin. In the present invention, the crosslinking degree of the COPNA resin is characterized by the gel content: referring to the ASTM D2765-11 standard, the gel content of the COPNA resin is tested by the THF extraction method.

[0023] Example 1:

[0024] Take 50 parts of coal liquefaction pitch and 150 parts of THF and put them into a reaction kettle, add 15 parts of paraformaldehyde and 2.5 parts of sulfuric acid, heat to 100 °C under normal pressure for pre-crosslinking reaction for 12 h, raise the temperature of the reaction kettle to 140 °C to evaporate THF while performing deep crosslinking, the viscosity of the system gradually increases until the sample in the reaction kettle becomes solid to end the reaction, and the product is mashed and discharged.

[0025] Example 2:

[0026] Take 50 parts of coal tar and 250 parts of DMF and put them into a reaction kettle. Add 100 parts of furfural and 15 parts of p-toluenesulfonic acid. Heat to 150 °C under atmospheric pressure for pre-crosslinking reaction for 6 h. Raise the temperature of the reaction kettle to 210 °C to carry out deep crosslinking while distilling off DMF. The viscosity of the system gradually increases until the sample in the reaction kettle becomes solid to end the reaction. After the product is mashed, it is discharged.

[0027] Example 3:

[0028] Take 50 parts of coal tar pitch and 150 parts of dioxane and put them into a reaction kettle. Add 150 parts of p-xylene glycol and 1.5 parts of benzenesulfonic acid. Heat to 130 °C under atmospheric pressure for pre-crosslinking reaction for 10 h. Raise the temperature of the reaction kettle to 150 °C to carry out deep crosslinking while distilling off dioxane. The viscosity of the system gradually increases until the sample in the reaction kettle becomes solid to end the reaction. After the product is mashed, it is discharged.

[0029] Example 4:

[0030] Take 50 parts of coal liquefaction pitch and 50 parts of THF and put them into a reaction kettle. Add 30 parts of paraformaldehyde and 2.5 parts of sulfuric acid. Heat to 80 °C under atmospheric pressure for pre-crosslinking reaction for 8 h. Raise the temperature of the reaction kettle to 120 °C to carry out deep crosslinking while distilling off THF. The viscosity of the system gradually increases until the sample in the reaction kettle becomes solid to end the reaction. After the product is mashed, it is discharged.

[0031] Example 5:

[0032] Take 50 parts of ethylene tar and 25 parts of NMP and put them into a reaction kettle. Add 80 parts of benzaldehyde and 25 parts of benzenesulfonic acid. Heat to 150 °C under atmospheric pressure for pre-crosslinking reaction for 8 h. Raise the temperature of the reaction kettle to 240 °C to carry out deep crosslinking while distilling off NMP. The viscosity of the system gradually increases until the sample in the reaction kettle becomes solid to end the reaction. After the product is mashed, it is discharged.

[0033] Example 6:

[0034] Take 50 parts of petroleum asphalt and 50 parts of THF and put them into a reaction kettle. Add 60 parts of paraformaldehyde and 10 parts of benzenesulfonic acid. Heat to 50 °C under atmospheric pressure for pre-crosslinking reaction for 8 h. Raise the reaction temperature to 120 °C to carry out deep crosslinking while distilling off THF. The viscosity of the system gradually increases until the sample in the reaction kettle becomes solid to end the reaction. After the product is mashed, it is taken out.

[0035] Example 7:

[0036] Take 10 parts of coal liquefaction pitch and 10 parts of THF in a reaction kettle. Add 8 parts of paraformaldehyde and 0.5 part of p-toluenesulfonic acid. Stir and heat at 120 °C and 0.5 MPa for 24 h to obtain a crosslinked product. After filtration and drying, the product is obtained.

[0037] Example 8:

[0038] Take 10 parts of petroleum asphalt and 10 parts of THF in a reaction kettle, add 12 parts of paraformaldehyde and 0.5 part of p-toluenesulfonic acid, stir, and heat at 120 °C and 2 MPa for 24 h to obtain a cross-linked product. After filtration and drying, the product is obtained.

[0039] Example 9:

[0040] Take 10 parts of ethylene tar and 40 parts of DMF in a reaction kettle, add 25 parts of paraformaldehyde and 2 parts of benzenesulfonic acid, stir, and heat at 220 °C and 10 MPa for 12 h to obtain a cross-linked product. After filtration and drying, the product is obtained.

[0041] Example 10:

[0042] Take 10 parts of coal tar and 30 parts of NMP in a reaction kettle, add 1 part of dimethoxymethane and 5 parts of p-toluenesulfonic acid, stir, and heat at 250 °C and 15 MPa for 48 h to obtain a cross-linked product. After filtration and drying, the product is obtained.

[0043] Comparative example:

[0044] Take 50 parts of coal liquefaction pitch and 15 parts of paraformaldehyde, mix them evenly in a reaction kettle, stir, and slowly add 2.5 parts of sulfuric acid in batches. After the addition is completed, heat to 140 °C for cross-linking reaction until the sample in the reactor becomes solid and the reaction ends. The solid product is mashed and poured out.

[0045] Application example:

[0046] Preparation of highly cross-linked COPNA resin-based hard carbon materials:

[0047] Examples 1, 4, 7, 8, Comparative example: The products are pre-oxidized at 300 °C for 6 h in an air atmosphere and carbonized at 1300 °C for 2 h in an inert atmosphere.

[0048] Examples 2, 5: The products are pre-oxidized at 350 °C for 3 h in an air atmosphere and carbonized at 1500 °C for 1 h in an inert atmosphere.

[0049] Examples 3, 9: The products are pre-oxidized at 250 °C for 9 h in an air atmosphere and carbonized at 1100 °C for 3 h in an inert atmosphere.

[0050] Examples 6, 10: The products are pre-oxidized at 300 °C for 9 h in an air atmosphere and carbonized at 1400 °C for 3 h in an inert atmosphere.

[0051] Application example test:

[0052] Layer spacing d 002 : Tested by a non-in-situ X-ray diffractometer, and the results are shown in Table 1 and the appendix Figure 1 、 2 。

[0053] Sodium storage performance: Assemble the carbon material into a sodium-ion half-cell, use the constant current charge-discharge mode, the test voltage range is 0.01 - 3.0V, first discharge and then charge, the test current density is 0.03A / g, and the reversible capacity and the first-cycle Coulomb efficiency of the first-cycle test are shown in Table 1

[0054] It can be seen from the comparison of the test results of the comparative examples and the examples that the gel content of the COPNA resin prepared in Example 1 is much higher than that of the comparative examples, and the same is true for other examples. This is mainly due to the reactants being dispersed in the solvent, which makes the molecules evenly dispersed, increases the probability of effective collision and reduces the diffusion limitation, and solves the problem of uneven mass transfer during the reaction. The XRD of the carbon material derived from the comparative example Figure 2 shows a sharp diffraction peak at 24°, d 002 <0.37nm, belonging to soft carbon materials. The XRD of the carbon materials derived from Example 1, Example 4, Example 7, and Example 8 Figure 1 shows a relatively flat bread-like peak. The d 002 of Examples 1 - 10 > 0.38nm, belonging to hard carbon materials. This is mainly due to the increase in crosslinking degree, which makes the structure of the derived carbon material far from graphitization. The increase of d 002 is more conducive to the insertion / extraction of Na + , so the sodium storage performance is also greatly improved

[0055] Table 1

[0056]

[0057] Table 1 is a data table of the gel content of the COPNA resin prepared in Examples 1 - 10 and the comparative examples, and the structure and sodium storage performance of their derived carbon materials

Claims

1. A preparation method of a highly cross-linked COPNA resin, characterized in that, The specific process is as follows: (1) Disperse the aromatic-rich heavy organic components in a solvent in a reaction kettle, and add a catalyst and a cross-linking agent; (2) The mixed system in step (1) undergoes a pre-crosslinking reaction under atmospheric pressure. After the pre-crosslinking reaction is completed, the temperature is raised to carry out a deep crosslinking reaction while removing the solvent. The deep crosslinked solid product is mashed to obtain a highly crosslinked COPNA resin; Or; The mixed system in step (1) undergoes a pressure crosslinking reaction. After the pressure crosslinking reaction is completed, the solid product is separated by filtration to obtain a highly crosslinked COPNA resin.

2. The preparation method of a highly crosslinked COPNA resin according to claim 1, characterized in that, The aromatic-rich heavy organic components are coal tar, ethylene tar, coal pitch, petroleum pitch or coal liquefied pitch; the solvent is tetrahydrofuran (THF), dioxane, dimethylformamide (DMF) or N-methylpyrrolidone (NMP); the catalyst is sulfuric acid, benzenesulfonic acid or p-toluenesulfonic acid; the cross-linking agent is trioxymethylene, paraformaldehyde, benzaldehyde, furfural, p-xylene glycol or dimethoxymethane.

3. The preparation method of a highly crosslinked COPNA resin according to claim 1, characterized in that, The mass ratio of the aromatic-rich heavy organic components, cross-linking agent, catalyst and solvent is: 100:10 - 300:3 - 50:50 - 500.

4. The preparation method of a highly crosslinked COPNA resin according to claim 1, characterized in that, The temperature of the pre-crosslinking reaction is 50 - 150 °C, and the reaction time is 6 - 12 h.

5. The preparation method of a highly crosslinked COPNA resin according to claim 1, characterized in that, The temperature of the deep crosslinking reaction is 120 - 240 °C until the sample in the reaction kettle becomes solid and the reaction ends.

6. The preparation method of a highly crosslinked COPNA resin according to claim 1, characterized in that, The temperature of the pressure crosslinking reaction is 120 - 250 °C, the pressure of the pressure crosslinking reaction is 0.5 - 15 MPa, and the pressure crosslinking reaction time is 12 - 48 h.

7. Use of the highly crosslinked COPNA resin prepared by the preparation method according to any one of claims 1-6, characterized in that, Specifically, it is applied to the preparation of hard carbon materials based on highly crosslinked COPNA resin.

8. The application according to claim 7, wherein The method for preparing hard carbon materials based on highly crosslinked COPNA resin is: subject the highly crosslinked COPNA resin to a pre-oxidation treatment at 250 - 350 °C for 3 - 9 h in an air atmosphere, and then perform a carbonization treatment at 1100 - 1500 °C for 1 - 3 h in an inert atmosphere to obtain hard carbon materials based on highly crosslinked COPNA resin.

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