Method for preparing mesophase pitch by using Lewis-Bronsted superacid

Abstract

The invention relates to the field of mesophase pitch carbon materials, in particular to the technical field of a method for preparing mesophase pitch by using # imgabs0 # superacid. Asphalt of different sources is adopted as a raw material, a superacid catalyst is uniformly mixed, and through a carbonization process in an inert atmosphere, the pitch is subjected to low-temperature catalytic condensation polymerization to form mesophase pitch with high anisotropic content, so that the reaction temperature is reduced, and the solubility and spinnability of the mesophase pitch are improved. The preparation method has the characteristics of wide raw material asphalt source, low price, simple preparation process method, environmental friendliness and the like, and is an ideal method for preparing high-quality mesophase asphalt.

Description

Technical Field

[0001] The present invention relates to the field of mesophase pitch carbon materials, and in particular to a method of using Lewis- Method for preparing mesophase asphalt with superacid and its application. Background Art

[0002] Driven by the "carbon peak and carbon neutrality" policy and the green and low-carbon technology revolution, traditional carbon-intensive industries are gradually being transformed and revolutionized. Therefore, the efficient and high-value utilization of asphalt, a by-product of coal chemical and petrochemical industries, has become a research hotspot. Due to its excellent physical and chemical properties, mesophase asphalt has become one of the excellent precursors for high-performance carbon fiber, high thermal conductivity foam carbon, ultra-high specific surface area activated carbon, high-quality needle coke, secondary battery negative electrode materials, etc. However, due to the high carbon content and low chemical activity of asphalt, the carbonization temperature required for its reaction is too high and the reaction process is uncontrollable, which ultimately seriously affects the subsequent application of carbon materials.

[0003] The catalytic polycondensation method was developed in the process of studying catalytic coking. This method is considered to be a preparation method that can significantly reduce the temperature of the reaction system after common mesophase preparation methods such as direct polycondensation, co-carbonization and hydrogen supply pyrolysis. Its reaction mechanism is a non-dehydrogenation cationic polymerization mechanism, which can achieve the preparation of mesophase at a relatively low reaction temperature. At present, the common catalyst systems are mainly HF / BF3 and AlCl3, both of which are typical Lewis- Superacid system. However, the HF in the HF / BF3 system is too corrosive to the equipment, resulting in extremely high requirements for the material of the reactor. The relatively mild AlCl3 system is relatively more friendly in terms of safety risks. However, previous studies only emphasized the amount of AlCl3, The acid defaults to a small amount of water in the material, resulting in a low catalytic activity of the system. Patent CN115521802A uses AlCl3 and isopropyl chloride as catalysts. Although the aluminum chloride catalytic system is also used, the active center generated by isopropyl chloride as a co-catalyst is an isopropyl carbon cation with a large steric hindrance, which is difficult to initiate during the alkylation process, resulting in a higher reaction temperature required to achieve the same anisotropic content of the mesophase asphalt. The present invention uses Acid as an initiator will not introduce heteroatoms into the product and the protons formed are highly active and have low steric hindrance. In summary, the catalytic method for preparing mesophase pitch can significantly reduce the reaction temperature and increase the mesophase content of the sample. However, among the two common catalytic systems, HF / BF3 is highly corrosive to the equipment, and the catalytic activity of the aluminum chloride catalytic system is relatively low. By formulating Lewis- Superacids can significantly improve catalytic activity and reduce corrosion of the catalytic system to equipment. Therefore, providing a method for preparing mesophase pitch with simple process, mild reaction and high efficiency is an urgent problem to be solved. Summary of the invention

[0004] According to the problem to be solved, the present invention provides a method of using Lewis- A method for preparing mesophase asphalt with super acid. The acid is a super acid. Through a simple catalytic polycondensation method, the evenly mixed asphalt and catalyst are heated and carbonized, so that the system releases more active centers, quickly initiates the reaction and reduces the activation energy of the system, thereby reducing the required reaction temperature of the system while ensuring the content of the intermediate phase. The preparation process has the advantages of abundant raw asphalt sources, low cost, simple and mild preparation process, and greatly reduced reaction temperature, and is suitable for large-scale industrial production.

[0005] A method using Lewis- The preparation steps of superacid to prepare mesophase asphalt are as follows:

[0006] Step (1): First, asphalt, Lewis acid and Acid drying to achieve anhydrous state;

[0007] Step (2): In an inert atmosphere, weigh a certain amount of asphalt, Lewis acid and Acid, mix evenly in a certain proportion and put into the reaction kettle and seal it;

[0008] Step (3): The reactor is heated to a certain reaction temperature, kept warm for a period of time, and then taken out, and the reactor is allowed to stand and cool to room temperature to obtain the mesophase asphalt.

[0009] Preferably: the asphalt in step (1) is one of coal tar asphalt, coal liquefaction asphalt, ethylene tar and petroleum asphalt or a mixture thereof; the Lewis acid is one of aluminum chloride, ferric chloride, zirconium chloride and boron fluoride, and The acid is one of methanol, formic acid, cyanoacetic acid, and chloroacetic acid.

[0010] Preferably, in step (2), the Lewis acid preferably accounts for 5 wt.% to 20 wt.% of the asphalt. The molar ratio of the acid is 1:(0.01~1); the present invention controls the amount of Lewis acid within the above range to achieve the best catalytic effect and catalytic efficiency and reduce the activation energy of the asphalt catalytic polycondensation reaction; the present invention has no special restrictions on the mixing method of the raw asphalt, Lewis acid and #imgpt13# acid, and the mixing method well known in the art can be used to achieve uniform mixing of the components.

[0011] Preferably, the heating rate in step (3) is 1-5°C / min, the reaction temperature is 200-350°C, and the insulation time is 6-10h. The present invention controls the heating rate, reaction temperature and insulation time within the above range to ensure a smooth reaction and avoid overreaction.

[0012] Beneficial effects of the present invention

[0013] The present invention provides a simple catalytic pyrolysis method to cause the protons in the active center of the asphalt system to surge and disperse around the aromatic molecules, quickly induce an alkylation reaction in the asphalt molecules at low temperature, and cause the aromatic sheet molecules to grow rapidly and complete oriented stacking under the attraction of the π electron cloud, forming a large number of nucleation sites, and quickly forming a wide-area intermediate phase asphalt at low temperature. The preparation process has the advantages of abundant raw asphalt sources, low cost, simple and mild preparation process, and greatly reduced reaction temperature, and is suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a polarized light micrograph of the sample after reaction in Example 1 of the present invention.

[0015] Figure 2 This is a polarized light micrograph of the sample after reaction in Example 2 of the present invention.

[0016] Figure 3 This is a polarized light micrograph of the sample after reaction in Example 3 of the present invention.

[0017] Figure 4 This is a polarized light micrograph of the sample after the reaction in Example 4 of the present invention.

[0018] Figure 5 This is a polarized light micrograph of the sample after reaction in Example 5 of the present invention.

[0019] The present invention is further described below by way of specific embodiments, but is not intended to limit the present invention.

[0020] Embodiment 1:

[0021] Step (1) Under an inert atmosphere, weigh 10 g of coal tar pitch, 1.0 g of anhydrous aluminum chloride and 0.300 ml of formic acid, mix them evenly and put them into a reaction kettle and seal them;

[0022] Step (2) The reactor in step (1) is heated to 350° C. at 4° C. / min and kept at this temperature for 6 hours to obtain the mesophase asphalt.

[0023] Polarized optical testing and Image J analysis results showed that the reaction sample exhibited a wide-area streamlined mesophase texture with an anisotropy content of up to 95%.

[0024] Embodiment 2:

[0025] Step (1) Under an inert atmosphere, weigh 10 g of coal tar pitch, 2.0 g of anhydrous aluminum chloride and 0.400 g of chloroacetic acid, mix them evenly and put them into a reaction kettle and seal them;

[0026] Step (2) The reactor in step (1) is heated to 250° C. at 1° C. / min and kept warm for 9 hours to obtain the mesophase asphalt.

[0027] Polarized optical testing and Image J analysis results showed that the reaction sample exhibited a wide-area streamlined mesophase texture with an anisotropy content of up to 92%.

[0028] Embodiment 3:

[0029] Step (1) Under an inert atmosphere, weigh 10 g of ethylene tar, 1.5 g of boron fluoride and 0.250 g of cyanoacetic acid, mix them evenly and put them into a reaction kettle and seal them;

[0030] Step (2) The reactor in step (1) is heated to 300° C. at 2° C. / min and kept at this temperature for 7 hours to obtain the mesophase asphalt.

[0031] The results of polarized optical testing and Image J analysis showed that the reaction sample exhibited a wide-area mesophase texture with an anisotropic content of up to 100%.

[0032] Embodiment 4:

[0033] Step (1) Under an inert atmosphere, weigh 10 g of coal liquefaction pitch, 0.5 g of anhydrous ferric chloride and 0.050 g of methanol, mix them evenly and put them into a reaction kettle and seal them;

[0034] Step (2) The reactor in step (1) is heated to 200° C. at 3° C. / min and kept warm for 10 hours to obtain the mesophase asphalt.

[0035] The results of polarized optical testing and Image J analysis showed that the reaction sample exhibited a mosaic mesophase texture with an anisotropic content of up to 89%.

[0036] Embodiment 5:

[0037] Step (1) Under an inert atmosphere, weigh 10 g of petroleum asphalt, 2.0 g of anhydrous zirconium chloride and 0.500 g of cyanoacetic acid, mix them evenly and put them into a reaction kettle and seal them;

[0038] Step (2) The reactor in step (1) is heated to 350° C. at 5° C. / min and kept at this temperature for 8 hours to obtain the mesophase asphalt.

[0039] The results of polarized optical testing and Image J analysis showed that the reaction sample exhibited a mosaic mesophase texture with an anisotropic content of up to 93%.

[0040] Comparative Example 1: Compared with Example 2, no co-catalyst was added, water was used as the default, the raw materials were unchanged, and the reaction conditions were the same. Finally, an isotropic pitch was obtained, and no anisotropic mesophase pitch was generated.

[0041] The preferred embodiments of the present invention have been specifically described above, but the present invention is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A kind of utilization The method for preparing mesophase asphalt using superacid comprises the following steps: Step (1): First, asphalt, Lewis acid and Acid drying to achieve anhydrous state; Step (2): In an inert atmosphere, weigh a certain amount of asphalt, Lewis acid and Acid, mix evenly in a certain proportion and put into the reaction kettle and seal it; Step (3): The reactor is heated to a certain reaction temperature, kept warm for a period of time, and then taken out, and the reactor is allowed to stand and cool to room temperature to obtain the mesophase asphalt.

2. The preparation method according to claim 1, wherein the asphalt in step (1) is one of coal tar pitch, coal liquefaction pitch, ethylene tar and petroleum asphalt or a mixture thereof; the Lewis acid is one of aluminum chloride, ferric chloride, zirconium chloride and boron fluoride, and The acid is one of methanol, formic acid, cyanoacetic acid, and chloroacetic acid.

3. The preparation method according to claim 1, wherein the Lewis acid in step (2) preferably accounts for 5 wt.% to 20 wt.% of the asphalt. The molar ratio of the acid is 1: (0.01-1); the present invention controls the amount of Lewis acid in the above range to achieve the best catalytic effect and catalytic efficiency, and reduce the activation energy of the asphalt catalytic polycondensation reaction; the present invention treats the raw material asphalt, Lewis acid and There is no particular limitation on the mixing method of the acid, and a mixing method well known in the art can be used to achieve uniform mixing of the components.

4. According to the preparation method of claim 1, the heating rate in step (3) is 1-5°C / min, the reaction temperature is 200-350°C, and the insulation time is 6-10h; the present invention controls the heating rate, reaction temperature and insulation time within the above range to ensure a smooth reaction and avoid overreaction.

5. The preparation method according to claim 1, wherein the preparation method of mesophase asphalt is characterized in that the mesophase asphalt contains the preparation method according to any one of claims 1 to 4.

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