High-softening-point isotropic asphalt as well as preparation method and application thereof

Abstract

The invention relates to the technical field of material preparation, in particular to high-softening-point isotropic asphalt as well as a preparation method and application thereof. The asphalt precursor is coal tar, ethylene tar, catalytic cracking oil slurry, petroleum residual oil and low-softening-point asphalt prepared from the coal tar, the ethylene tar, the catalytic cracking oil slurry and the petroleum residual oil or low-softening-point asphalt prepared from the coal tar, the ethylene tar, the catalytic cracking oil slurry and the petroleum residual oil, and the softening point is 1t; 150 DEG C; the cross-linking agent comprises an anhydride substance; and the oxidizing agent is one or more of dicumyl peroxide, p-isopropyl phenyl phenol, 2, 4-diisopropyl phenol, and 2, 3-dimethyl-2, 3-diphenyl butane. The isotropic asphalt with a high softening point is obtained by taking a cheap asphalt precursor as a raw material, adopting a segmented reaction and carrying out chemical polymerization reaction on a cross-linking agent and a small molecular asphalt precursor, and can be used as a coating material of a graphite negative electrode in a lithium ion battery and / or a raw material of a hard carbon negative electrode of a sodium ion battery.

Description

Technical Field

[0001] The present invention relates to the technical field of material preparation, and in particular to a high-softening-point isotropic asphalt and a preparation method and application thereof. Background Art

[0002] The aromatic molecules of isotropic asphalt are arranged in a disordered plane. The properties of the asphalt are the same in all directions. When melted, it is a Newtonian or nearly Newtonian fluid. Isotropic asphalt is a high-quality precursor of carbon materials. The carbon materials prepared from it are difficult to graphitize. The high softening point isotropic asphalt is carbonized on the surface of lithium battery graphite negative electrode, which can effectively improve its cycle performance and rate performance. It is an important material for upgrading lithium battery graphite negative electrode. In addition, this material is also widely used in the preparation of high value-added products such as sodium ion battery hard carbon negative electrode and asphalt-based spherical activated carbon. Therefore, how to prepare high softening point isotropic asphalt with excellent performance has become one of the current research hotspots in the field of carbon materials.

[0003] The preparation process of isotropic asphalt has a great influence on its performance. The traditional methods for preparing isotropic asphalt include: air oxidation, thermal polycondensation, hydrogenation, co-carbonization, atmospheric and vacuum distillation, solvent extraction to remove light components of asphalt, and adding catalysts (such as aluminum chloride, iodine, sulfur, carbon black, etc.) to promote the polymerization of asphalt components. Among them, air oxidation and thermal polycondensation are the most widely used methods. Both methods promote the dehydrogenation reaction of asphalt. Air oxidation will form oxygen free radicals, which will cause the internal molecules of asphalt to produce cross-linked structures. Thermal polycondensation tends to form aromatic planar macromolecules, which are often accompanied by the generation of intermediate phases during the polycondensation process. In addition, the asphalt prepared by air oxidation has a low softening point, while the asphalt prepared by thermal polycondensation has the disadvantages of not high coking value, high H content, and low carbonization yield. Therefore, it is urgent to develop an effective method for preparing isotropic asphalt with high softening point, excellent rheological properties, high carbon yield and low ash content to meet the requirements of asphalt products for graphite negative electrodes of lithium-ion batteries and hard carbon materials of sodium-ion batteries. Summary of the invention

[0004] In view of the problems existing in the current preparation methods of isotropic asphalt with a high softening point, the present invention uses a cheap asphalt precursor as a raw material, adopts a staged reaction, and obtains isotropic asphalt with a high softening point by chemical polymerization reaction between a cross-linking agent and a small molecule asphalt precursor. The isotropic asphalt can be used as a coating material for graphite negative electrodes in lithium-ion batteries and / or a raw material for hard carbon negative electrodes in sodium-ion batteries.

[0005] The technical solution of the present invention is as follows:

[0006] A high softening point isotropic asphalt, comprising the following raw materials: an asphalt precursor, a cross-linking agent, and an oxidant;

[0007] The asphalt precursor includes an asphalt intermediate prepared from coal tar, ethylene tar, catalytic cracking oil slurry, and petroleum residue, and the softening point of the asphalt intermediate is less than 150°C;

[0008] The cross-linking agent includes anhydride substances;

[0009] The oxidant is one or more of dicumyl peroxide, p-cumyl phenol, 2,4-diisopropylphenol and 2,3-dimethyl-2,3-diphenylbutane.

[0010] Preferably, the cross-linking agent includes one or more of maleic anhydride, phthalic anhydride, benzoic anhydride, acetic anhydride, ethylpropionic anhydride, succinic anhydride, acetic anhydride, propionic anhydride, maleic anhydride, and trimellitic anhydride.

[0011] Preferably, the mass ratio of the cross-linking agent to the asphalt is 1 to 20:100, and the mass ratio of the oxidant to the asphalt is 0.5 to 5:100.

[0012] Another object of the present invention is to provide a method for preparing the above-mentioned high softening point isotropic asphalt, comprising the following steps:

[0013] (1) heating the asphalt precursor under an inert atmosphere to obtain an asphalt intermediate with a low softening point of <150°C;

[0014] (2) grinding the asphalt intermediate of step (1), mixing it evenly with a cross-linking agent and an oxidant, and heating it under an inert atmosphere to obtain an isotropic asphalt with a softening point of 200-300° C.;

[0015] (3) Adding the isotropic asphalt of step (2) into a short-path molecular distiller to obtain an isotropic asphalt having a softening point > 280°C.

[0016] Preferably, the heating conditions in step (1) are: temperature 150-250° C., time 1-10 h, and inert gas flow rate 1-3 L / kg·min.

[0017] Preferably, the heating conditions in step (2) are: heating temperature 250-320° C., heating time 2-10 h.

[0018] Preferably, the control parameters of the short-range molecular distiller in step (3) are: distiller temperature of 300-350° C., vacuum pressure of 80-200 Pa, rotation speed of 50-200 rpm, and distillation time of 1-4 h.

[0019] Another object of the present invention is to protect the use of the above-mentioned high softening point isotropic asphalt or the high softening point isotropic asphalt prepared by the above-mentioned preparation method in graphite negative electrode materials for lithium-ion batteries.

[0020] Preferably, it is used as a coating asphalt material for graphite negative electrodes of lithium-ion batteries.

[0021] Another object of the present invention is to protect the use of the above-mentioned high softening point isotropic asphalt or the high softening point isotropic asphalt prepared by the above-mentioned preparation method in hard carbon negative electrode materials for sodium ion batteries.

[0022] Beneficial effects of the present invention:

[0023] (1) The first step is to use atmospheric distillation technology to remove light components from the tar raw material, effectively increasing the softening point of asphalt. And its light components can be accurately separated according to subsequent processes to produce high-value-added chemical products such as naphthalene, methyl naphthalene, naphtha, petroleum resin, etc., thereby improving the comprehensive utilization rate of asphalt precursor tar.

[0024] (2) The second step uses chemical reaction polymerization technology to promote the polymerization reaction of asphalt molecules under the action of cross-linking agents and oxidants to form a network-like macromolecular structure, which greatly improves the softening point of asphalt, while inhibiting the generation of intermediate phase plane molecules and promoting the formation of isotropic structure.

[0025] (3) In the third step, molecular distillation technology is used to remove the light components that have not reacted or have not reacted to a high degree in step 2, further improving the softening point and coking value of the isotropic asphalt, while maintaining the fluidity and wettability of the asphalt. In addition, the production process is continuous and has higher production efficiency.

[0026] (4) The prepared high softening point isotropic asphalt has high isotropy and disordered structure, a softening point exceeding 280°C, a coking value exceeding 70%, and a quinoline insoluble content of less than 3%, making it a high-quality high-end carbon material raw material. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a polarizing microscope image of the isotropic asphalt of Example 1;

[0028] Figure 2 is the viscosity-temperature curve of the isotropic asphalt in Examples 1-3;

[0029] Figure 3 This is the XRD diagram of the hard carbon negative electrode material for sodium ion battery prepared from the asphalt of Examples 1-3. Specific implementation methods

[0030] The present invention is further described in detail below by way of examples so that those skilled in the art can better understand the present invention, but the present invention is not limited to the following examples.

[0031] Example 1

[0032] A method for preparing high softening point isotropic asphalt comprises the following steps:

[0033] (1) 10 kg of ethylene tar was added to a high-temperature reactor and heated to 200° C. for 5 h at a nitrogen flow rate of 15 L / min to obtain an asphalt intermediate with a low softening point of about 130° C.

[0034] (2) After 10 kg of low softening point asphalt is ground and passed through a 200-mesh sieve, it is evenly mixed with 2 kg of maleic anhydride and 0.5 kg of diisopropylbenzene peroxide. The mixture is then added to a high-temperature reactor and heated to 280°C for 10 h under a nitrogen atmosphere to obtain an isotropic asphalt with a softening point of about 250°C.

[0035] (3) Add the isotropic asphalt with a softening point of about 250°C into a short-path molecular distiller, and distill at a temperature of 330°C while controlling the vacuum pressure of the short-path molecular distiller to 100 Pa. Distill at a rotation speed of 100 rpm for 4 hours to obtain the isotropic asphalt with a softening point of 326°C.

[0036] from Figure 1 It can be clearly seen from the polarized micrographs of the asphalt that the prepared asphalt has the same uniform polarized image and the surface asphalt has completely isotropic characteristics. Figure 2 It can be seen that the viscosity of asphalt decreases sharply with increasing temperature, and gradually becomes stable after reaching a certain temperature, and its softening point reaches 326℃. Figure 3 It shows that the molecular structure of asphalt is amorphous.

[0037] Example 2

[0038] A method for preparing high softening point isotropic asphalt comprises the following steps:

[0039] (1) 10 kg of coal tar was added to a high temperature reactor and heated to 250° C. for 3 h at a nitrogen flow rate of 30 L / min to obtain an asphalt intermediate with a low softening point of about 120° C.

[0040] (2) After 10 kg of low softening point asphalt is ground and passed through a 200-mesh sieve, it is evenly mixed with 0.1 kg of phthalic anhydride and 0.05 kg of p-isopropylphenyl phenol. The mixture is then added to a high-temperature reactor and heated to 320°C for 2 h under a nitrogen atmosphere to obtain an isotropic asphalt with a softening point of about 240°C.

[0041] (3) Add the isotropic asphalt with a softening point of about 240°C into a short-path molecular distiller, and distill at a temperature of 350°C while controlling the vacuum pressure of the short-path molecular distiller to 200 Pa. Distill at a rotation speed of 200 rpm for 1 hour to obtain the isotropic asphalt with a softening point of 285°C.

[0042] from Figure 2It can be seen that the viscosity of the asphalt decreases sharply with increasing temperature, and gradually becomes stable after reaching a certain temperature. Its softening point reaches 285°C, which is lower than the softening point of the asphalt prepared in Example 1. Figure 3 It shows that the molecular structure of asphalt is amorphous, the molecular stacking order is not high, and it is arranged in a disorderly manner.

[0043] Example 3

[0044] A method for preparing high softening point isotropic asphalt comprises the following steps:

[0045] (1) 10 kg of catalytic cracking oil slurry was added to a high-temperature reactor and heated to 150° C. for 10 h at a nitrogen flow rate of 10 L / min to obtain an asphalt intermediate with a low softening point of about 120° C.

[0046] (2) After 10 kg of low softening point asphalt is ground and passed through a 200-mesh sieve, it is evenly mixed with 1 kg of benzoic anhydride and 0.3 kg of 2,4-diisopropylphenol. The mixture is then added to a high-temperature reactor and heated to 300°C for 5 hours under a nitrogen atmosphere to obtain an isotropic asphalt with a softening point of about 255°C.

[0047] (3) Add the isotropic asphalt with a softening point of about 255°C into a short-path molecular distiller. At a temperature of 300°C, control the vacuum pressure of the short-path molecular distiller to 80Pa, and distill for 4 hours at a rotation speed of 50rpm to obtain the isotropic asphalt with a softening point of 305°C.

[0048] Example 4

[0049] A method for preparing high softening point isotropic asphalt comprises the following steps:

[0050] (1) 10 kg of ethylene tar pitch with a softening point of 80°C was added to a high-temperature reactor, heated to 250°C for 1 hour at a nitrogen flow rate of 20 L / min, and a pitch intermediate with a low softening point of about 148°C was obtained.

[0051] (2) After 10 kg of low softening point asphalt is ground and passed through a 200-mesh sieve, it is evenly mixed with 0.5 kg of succinic anhydride and 0.2 kg of 2,3-dimethyl-2,3-diphenylbutane. The mixture is then added to a high-temperature reactor and heated to 250°C for 10 h under a nitrogen atmosphere to obtain an isotropic asphalt with a softening point of about 243°C.

[0052] (3) The isotropic asphalt with a softening point of about 243°C is added to a short-path molecular distiller. At a temperature of 330°C, the vacuum pressure of the short-path molecular distiller is controlled to be 80 Pa. Under the rotation condition of 150 rpm, the distillation treatment is carried out for 2 hours to obtain the isotropic asphalt with a softening point of 313°C.

[0053] Comparative Example 1

[0054] A method for preparing high softening point isotropic asphalt comprises the following steps:

[0055] (1) 10 kg of ethylene tar was added to a high-temperature reactor and heated to 200° C. for 5 h at a nitrogen flow rate of 15 L / min to obtain an asphalt intermediate with a low softening point of about 130° C.

[0056] (2) Add the isotropic asphalt with a softening point of about 130°C into a short-path molecular distiller, and distill at a temperature of 330°C while controlling the vacuum pressure of the short-path molecular distiller to 100 Pa. Distill at a rotation speed of 100 rpm for 4 hours to obtain the isotropic asphalt with a softening point of 265°C.

[0057] Comparative Example 2

[0058] A method for preparing high softening point isotropic asphalt comprises the following steps:

[0059] (1) 10 kg of ethylene tar was added to a high-temperature reactor and heated to 200° C. for 5 h at a nitrogen flow rate of 15 L / min to obtain an asphalt intermediate with a low softening point of about 130° C.

[0060] (2) After 10 kg of low softening point asphalt is ground and passed through a 200-mesh sieve, it is evenly mixed with 2 kg of maleic anhydride and 0.5 kg of diisopropylbenzene peroxide. The mixture is then added to a high-temperature reactor and heated to 280°C for 10 h under a nitrogen atmosphere to obtain an isotropic asphalt with a softening point of 252°C.

[0061] Implementation effect example 1 - asphalt coating

[0062] The asphalt of Examples 1-4 is mixed with spherical natural graphite in a ratio of 3 to 10%, and then coated using a melt coating machine. Subsequently, the mixture is heated to 1200° C. in a nitrogen atmosphere to obtain coated spherical natural graphite, which is used as a negative electrode material for lithium-ion batteries.

[0063] Implementation effect example 2 - Raw material for hard carbon negative electrode

[0064] The asphalt of Examples 1-4 is subjected to pre-oxidation, low-temperature carbonization and high-temperature carbonization to obtain a hard carbon material, which is used as a negative electrode material for a sodium ion battery.

[0065] Table 1 Comparison of the performance of the negative electrode materials prepared in Examples 1-4 and Comparative Examples 1-3

[0066]

Claims

1. A high softening point isotropic asphalt, characterized in that: The raw materials include: asphalt precursor, cross-linking agent, oxidant; The asphalt precursor includes an asphalt intermediate prepared from coal tar, ethylene tar, catalytic cracking oil slurry, and petroleum residue, and the softening point of the asphalt intermediate is less than 150°C; The cross-linking agent includes anhydride substances; The oxidant is one or more of dicumyl peroxide, p-cumyl phenol, 2,4-diisopropylphenol and 2,3-dimethyl-2,3-diphenylbutane.

2. The high softening point isotropic asphalt according to claim 1, characterized in that: The cross-linking agent includes one or more of maleic anhydride, phthalic anhydride, benzoic anhydride, acetic anhydride, ethylpropionic anhydride, succinic anhydride, acetic anhydride, propionic anhydride, maleic anhydride, and trimellitic anhydride.

3. The high softening point isotropic asphalt according to claim 1 or 2, characterized in that: The mass ratio of the cross-linking agent to the asphalt is 1-20:100, and the mass ratio of the oxidant to the asphalt is 0.5-5:

100.

4. A method for preparing the high softening point isotropic asphalt according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) heating the asphalt precursor under an inert atmosphere to obtain an asphalt intermediate with a low softening point of <150°C; (2) grinding the asphalt intermediate of step (1), mixing it evenly with a cross-linking agent and an oxidant, and heating it under an inert atmosphere to obtain an isotropic asphalt with a softening point of 200-300° C.; (3) Adding the isotropic asphalt of step (2) into a short-path molecular distiller to obtain an isotropic asphalt having a softening point > 280°C.

5. The preparation method according to claim 4, characterized in that: The heating conditions in step (1) are: temperature 150-250° C., heating time 1-10 h, and inert gas flow rate 1-3 L / kg·min.

6. The preparation method according to claim 4, characterized in that: The heating conditions in step (2) are: heating temperature 250-320° C., heating time 2-10 h.

7. The preparation method according to claim 4, characterized in that: The control parameters of the short-range molecular distiller in step (3) are: distiller temperature of 300-350° C., vacuum pressure of 80-200 Pa, rotation speed of 50-200 rpm, and distillation time of 1-4 h.

8. Use of the high softening point isotropic pitch described in any one of claims 1 to 3 or the high softening point isotropic pitch prepared by the preparation method shown in any one of claims 4 to 6 in graphite negative electrode materials for lithium-ion batteries.

9. The use according to claim 8, characterized in that: Used as asphalt coating material for graphite negative electrodes of lithium-ion batteries.

10. Use of the high softening point isotropic asphalt described in any one of claims 1 to 3 or the high softening point isotropic asphalt prepared by the preparation method shown in any one of claims 4 to 6 in hard carbon negative electrode materials for sodium ion batteries.

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