Process for the preparation of an isotropic bitumen and a high softening point sheathing bitumen

Abstract

The present application relates to a preparation process of isotropic pitch and high softening point coating pitch, which uses aromatic oil as raw material oil, and bio-tar or / and bio-pitch as co-carbonization agent. The pre-polymer material is obtained by pre-polymerization reaction of the bottom into the pre-polymerization reactor under the induction of oxygen-containing linear polymer. The photosensitive oxidation crosslinking agent is added to the pre-polymer material, the material distribution tray in the middle of the oxidation crosslinking reaction tower is fed, and the oxidation crosslinking gas enters from the lower part of the crosslinking reaction tower through the gas distributor. The obtained crosslinking pitch product is discharged from the bottom of the reaction tower. The crosslinking pitch then enters the middle of the polymerization reactor, and the polycondensation reaction occurs under the induction of high-energy electron beam irradiation. The polycondensation pitch product is obtained from the lower part of the polymerization reactor. The polycondensation pitch product enters the upper part of the extraction separation tower, and the sub / supercritical solvent enters the lower part of the extraction separation tower. The two-phase countercurrent contact extraction separation is carried out, and the isotropic pitch and high softening point coating pitch are obtained after the extraction solvent is separated.

Description

Technical Field

[0001] This invention relates to a preparation process for isotropic asphalt and high softening point coated asphalt, belonging to the field of advanced novel carbon material preparation technology. Background Technology

[0002] The raw materials used to produce lithium batteries mainly include four parts: positive electrode material, negative electrode material, electrolyte, and separator. Among them, the positive electrode material is the key material that determines the safety, performance, cost, and lifespan of the battery, accounting for about 30% of the battery manufacturing cost. The technology and market for negative electrode materials are relatively mature, and the cost ratio is the lowest, accounting for about 10% of the battery manufacturing cost.

[0003] The main commercially available lithium-ion battery anode materials are graphite-based (including natural graphite, artificial graphite, and MCMB). Other materials, such as soft carbon, hard carbon, silicon / carbon composites, and lithium titanate, are still in the experimental development stage and limited pilot production. To overcome some structural defects inherent in graphite, a coating process is usually performed to coat the graphite surface with a layer of amorphous carbon to reduce its initial irreversible capacity and improve cycle performance. Therefore, the production process and performance control of coated asphalt have become a research hotspot. Oxidative crosslinking is the most commonly used process for producing coated asphalt. CN114752397A discloses a method for preparing coated asphalt, in which refined coal liquefaction asphalt is subjected to vacuum distillation, and the resulting light component asphalt undergoes a crosslinking reaction to finally obtain low-softening-point coated asphalt and high-softening-point coated asphalt. CN115093874A discloses a method for preparing petroleum-based coated asphalt, which also employs an oxidative crosslinking reaction. By using external viscosity reducers and reflux viscosity reducers, the transformation of β-resin to α-resin is effectively prevented, ensuring the high softening point and low quinoline insoluble content of the prepared coated asphalt. CN114426852B discloses a method for preparing high softening point coated asphalt, in which heavy oil feedstock undergoes pre-crosslinking treatment in the presence of a catalyst and a crosslinking agent, followed by deep oxidative crosslinking and vacuum purging to obtain high softening point asphalt. CN115093872A discloses a method for preparing coated asphalt, in which ethylene tar is thoroughly mixed with catalytic slurry and impurities are removed, followed by sequential oxidative crosslinking catalytic reaction and polycondensation catalytic reaction. The resulting crude asphalt product is extracted to obtain coated asphalt, achieving the effects of reducing quinoline insoluble content, increasing carbon macromolecule content, and lowering softening point. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and design a process for producing isotropic asphalt and high softening point coated asphalt. Using aromatic oils such as ethylene tar, catalytic slurry, and coal tar fractions as raw materials, and bio-tar and / or bio-asphalt as co-carbonizing agents, the process integrates various steps and devices, including an oxygen-containing linear polymer-induced polymerization reactor, an oxidative cross-linking reaction tower, a high-energy electron beam irradiation tower, and an extraction separation tower, to produce high-performance isotropic asphalt. The heavier isotropic asphalt components are treated in a shallow thermal polycondensation reactor to prepare high-softening-point coated asphalt with excellent performance, thus optimizing the preparation method.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A process for preparing isotropic asphalt and high softening point coated asphalt, using aromatic oils such as ethylene tar, catalytic slurry oil, and coal tar fractions as feedstocks, and biotar and / or bioasphalt as co-carbonizing agents, includes the following specific steps:

[0007] (1) The raw oil and 5-40 wt% co-carbonizing agent are thoroughly mixed and preheated, and then enter the prepolymerization reactor from the bottom. Under the induction of oxygen-containing linear polymers, a prepolymerization reaction is carried out to obtain the prepolymer material.

[0008] The prepolymerization reaction temperature is 150-350℃, and the residence time is 0.5-2h;

[0009] The amount of oxygen-containing linear polymer added is 5-10 wt% of the total mass of the feedstock oil and co-carbonizing agent mixture.

[0010] Oxygen-containing linear polymers include, but are not limited to, polyethylene glycol, polyvinyl alcohol, polyvinyl chloride, polybutylene biphenyl phthalate, or polyacrylic acid;

[0011] (2) Add 1-5% photosensitive oxidative crosslinking agent to the prepolymer material. After the photosensitive oxidative crosslinking agent is mixed with the prepolymer material, it enters the material distribution tray in the middle of the oxidative crosslinking reaction tower. The oxidative crosslinking gas comes from the bottom of the oxidative crosslinking reaction tower through the gas distributor and comes into countercurrent contact with the prepolymer material and undergoes an oxidative crosslinking reaction. The oil and gas generated during the oxidative crosslinking process escape from the top of the oxidative crosslinking reaction tower, and the obtained crosslinked asphalt product is discharged from the bottom of the oxidative crosslinking reaction tower.

[0012] The photosensitive oxidative crosslinking agent includes, but is not limited to, benzophenone derivatives, α-hydroxy ketones, or phenyl dimethyl ketal; the oxidative crosslinking reaction temperature is 200-350℃, the prepolymer material residence time is 1-10h, and the oxidative crosslinking gas used includes, but is not limited to, air, oxygen, ozone / nitrogen mixture, etc., with a gas flow rate of 0.5-5.0 L·min. -1 ·kg -1 ;

[0013] (3) The cross-linked asphalt obtained from the bottom discharge enters from the middle of the high-energy electron beam irradiation tower and undergoes a condensation reaction under the induction of high-energy electron beam irradiation to generate condensation asphalt products with relatively uniform molecular weight distribution and some light oil and gas components. The light oil and gas components are condensed and recovered through a hot high-pressure separator and a cold low-pressure separator.

[0014] The high-energy electron beam irradiation dose is 10–50 kGy, the polymerization reaction temperature is 380–450℃, the reaction pressure is 0.1–3 MPa, and the reaction residence time is 2–8 h.

[0015] (4) The condensation pitch product at the bottom of the high-energy electron beam irradiation-induced condensation tower enters the supercritical extraction separation tower. The extraction solvent enters from the bottom of the supercritical extraction separation tower in the supercritical state, and the two phases are extracted and separated by countercurrent contact. The material at the top of the extraction separation tower, after the extraction solvent is separated, yields isotropic pitch. The carbon residue of the isotropic pitch is 45-55%, and the softening point is 200-250℃.

[0016] A subcritical / supercritical solvent countercurrent / continuous extraction separation process was used to controllably separate condensed pitch components according to their relative molecular weight. The extraction solvents could be selected from n-pentane, n-heptane, cyclohexane, benzene, toluene, xylene, ethylbenzene, and tetrahydrofuran, with a solvent-to-oil volume ratio of 1–20; the extraction temperature was 300–360℃, and the extraction pressure was between 2.0 and 6.0 MPa.

[0017] (5) The heavier asphalt components at the bottom of the extraction and separation tower are separated and the extraction solvent is removed to obtain high softening point coated asphalt with a softening point of 220-280℃, a carbon residue of ≥70%, and quinoline insoluble matter of ≤1%.

[0018] In this invention, the alkyl side chains surrounding the aromatic core of biotar or bioasphalt molecules contain a large number of oxygen-containing functional groups, which readily pyrolyze to generate free radicals upon heating, exhibiting high reactivity. During the prepolymerization process, the free radicals generated by the pyrolysis of the oxygen-containing functional groups can effectively promote polymerization and condensation reactions between aromatic molecules, generating polycyclic aromatic hydrocarbon molecules with higher molecular weights and increasing the yield of the asphalt product.

[0019] At the prepolymerization reaction temperature, oxygen-containing linear polymers undergo pyrolysis to generate a large number of small molecule free radicals. These free radicals induce the activation of aromatic molecules in the form of hydrogen abstraction. The activated aromatic molecules combine in the form of methylene "bridging" to obtain polycyclic aromatic macromolecules with high linearity, which significantly improves the flexibility of asphalt molecules and makes them exhibit high spinnability. At the same time, the free radicals generated by the cracking of oxygen-containing linear polymers also combine with asphalt product molecules, increasing the number of alkyl side chains around the aromatic core, which helps to improve the oxidation reactivity of isotropic asphalt and the wetting properties of coated asphalt.

[0020] This invention uses a photosensitive oxidative crosslinking agent. During the oxidative crosslinking process, bridge bonds are formed between linear polycyclic aromatic hydrocarbon molecules with fewer aromatic rings, transforming them into three-dimensional linear polycyclic aromatic hydrocarbon molecules with higher molecular weight. This allows oxygen-containing functional groups to be located at the side chain positions of the polycyclic aromatic hydrocarbons, which can effectively improve the removal of oxygen-containing functional groups during induced polycondensation and improve the quality of asphalt.

[0021] In this invention, the photosensitive oxidative crosslinking agent is activated by high-energy electron beam irradiation during the induced polycondensation reaction, thereby activating the crosslinking agent as a bridging structure to induce the reaction, remove oxygen-containing functional groups, and generate a large number of free radicals. The free radicals further combine with the asphalt product molecules to generate high-quality isotropic asphalt products.

[0022] This invention also uses supercritical extraction separation, with the solvent used being carried out in a supercritical state. This allows for the clear separation of isotropic asphalt products into isotropic asphalt and high softening point coated asphalt.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] (1) The raw materials involved in this invention are abundant and have a high degree of freedom; the design is reasonable, the production process is precise, the raw material processing depth is high, the equipment requirements are low, and it is easy to industrialize. By optimizing the conditions for producing isotropic asphalt and high softening point coated asphalt, the production device structure is more compact and reasonable, the yield is improved, energy consumption is reduced, and the configuration of each production process is optimized, which greatly reduces the preparation cost of isotropic asphalt and high softening point coated asphalt and has high industrial value.

[0025] (2) The isotropic asphalt produced by the process of oxygen-containing linear polymer induced polymerization reactor, oxidative crosslinking reaction tower, high-energy electron beam irradiation tower and supercritical extraction separation tower has excellent properties of high softening point and high carbon residue.

[0026] (3) The extraction and separation tower process can also extract high softening point coated asphalt. Attached Figure Description

[0027] Figure 1 This invention describes the preparation process of isotropic asphalt and high softening point coated asphalt. The process includes: 1. an oxygen-containing linear polymer-induced polymerization reactor; 2. an oxidative cross-linking reaction tower; 3. a high-energy electron beam irradiation tower; 4. an extraction separation tower; 5. a hot high-pressure separator; 6. a cold low-pressure separator; and 7. a pump. Detailed Implementation

[0028] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments:

[0029] Example 1

[0030] 350 kg of ethylene tar, 60 kg of bio-tar, and 90 kg of bio-asphalt were added to an oxygen-containing linear polymer-induced polymerization reactor, along with 45 kg of polyacrylic acid. The reaction was induced at 200°C for 1.5 h to obtain a pre-polymerized oil. 1% (by mass) of a benzophenone derivative was added to the pre-polymerized oil, and the mixture was then passed into an oxidative crosslinking reaction tower. The reaction was carried out at 330°C for 6 h, with an air flow rate of 5.0 L / min. -1 ·kg -1 Oxidative crosslinking was performed to obtain crosslinked asphalt products. These were then polymerized in a high-energy electron beam irradiation tower at 2 MPa, a polymerization temperature of 400℃, a residence time of 4 h, and a high-energy electron beam irradiation dose of 40 kGy to obtain condensation asphalt. Isotropic asphalt and heavier condensation asphalt components were obtained through a supercritical extraction separation tower. The isotropic asphalt had a carbon residue of 50% and a softening point of 240℃. The heavier asphalt component at the bottom of the extraction separation tower was extracted; the high softening point coated asphalt had a softening point of 270℃, a carbon residue of 74%, and 0.6% quinoline insolubles.

[0031] Example 2

[0032] 200 kg of ethylene tar, 150 kg of coal tar, 90 kg of bio-tar, and 60 kg of bio-asphalt were added to an oxygen-containing linear polymer-induced polymerization reactor, along with 40 kg of polyacrylic acid. The reaction was carried out at 220°C for 2 hours to induce polymerization, yielding a pre-polymerized oil. 3% (by weight) of α-hydroxy ketone was added to the pre-polymerized oil, and the mixture was then passed into an oxidative crosslinking reaction tower. The reaction was carried out at 280°C for 8 hours, with an air flow rate of 4.0 L / min. -1 ·kg -1 Oxidative crosslinking was performed to obtain oxidatively crosslinked slurry; it was then passed through a high-energy electron beam irradiation tower and polymerized under the conditions of 1 MPa, polymerization temperature of 390℃, reaction residence time of 6 h, and high-energy electron beam irradiation dose of 50 kGy to obtain condensation asphalt; isotropic asphalt and heavier condensation asphalt components were obtained through an extraction separation tower. The isotropic asphalt had a carbon residue of 55% and a softening point of 260℃. The heavier asphalt component at the bottom of the extraction separation tower was extracted, and the high softening point coated asphalt had a softening point of 250℃, a carbon residue of 73%, and quinoline insolubles of 0.7%.

Claims

1. A preparation process for isotropic asphalt and high softening point coated asphalt, characterized in that, It includes the following specific steps: (1) After the feedstock oil and co-carbonizing agent are fully mixed and preheated, they enter the prepolymerization reactor from the bottom and undergo a prepolymerization reaction under the induction of oxygen-containing linear polymers to obtain prepolymer material; the prepolymerization reaction temperature is 150-350℃ and the residence time is 0.5-2h; the amount of co-carbonizing agent added is 5%~40% of the mass of feedstock oil; the amount of oxygen-containing linear polymer added is 5-10% of the total mass of feedstock oil and co-carbonizing agent; the feedstock oil is aromatic oil, selected from one or more of ethylene tar, catalytic slurry oil or coal tar fraction; the co-carbonizing agent is bio-tar and / or bio-asphalt; the oxygen-containing linear polymer is selected from one or more of polyethylene glycol, polyvinyl alcohol, polyvinyl chloride, polybutylene diphthalate or polyacrylic acid; (2) A photosensitive oxidative crosslinking agent is added to the prepolymer material. After the photosensitive oxidative crosslinking agent is mixed with the prepolymer material, it enters the material distribution tray in the middle of the oxidative crosslinking reaction tower. The oxidative crosslinking gas comes from the bottom of the oxidative crosslinking reaction tower through the gas distributor and comes into countercurrent contact with the prepolymer material to undergo an oxidative crosslinking reaction. The oil and gas generated during the oxidative crosslinking process escape from the top of the oxidative crosslinking reaction tower, and the obtained crosslinked asphalt product is discharged from the bottom of the oxidative crosslinking reaction tower. The amount of photosensitive oxidative crosslinking agent added is 1-5% of the mass of the prepolymer material; the oxidative crosslinking reaction temperature is 200-350℃, the residence time of the prepolymer material is 1-10h, and the oxidative crosslinking gas flow rate is 0.5-5.0 L·min. -1 ·kg -1 The photosensitive oxidative crosslinking agent is selected from one of benzophenone derivatives, α-hydroxy ketones, or phenyl dimethyl ketal; the oxidative crosslinking gas is selected from one of ozone / nitrogen mixture, air, or oxygen. (3) The cross-linked asphalt obtained from the bottom discharge enters the middle of the high-energy electron beam irradiation tower and undergoes a condensation reaction under the induction of high-energy electron beam irradiation to generate condensation asphalt products with relatively uniform molecular weight distribution and some light oil and gas components; the high-energy electron beam irradiation dose is 10~50 kGy, the polymerization reaction temperature is 380-450 ℃, the reaction pressure is 0.1~3MPa, and the reaction residence time is 2~8h; (4) The condensation pitch product at the bottom of the high-energy electron beam irradiation tower enters the supercritical extraction separation tower. The extraction solvent enters from the bottom of the supercritical extraction separation tower in the supercritical state, and the two phases are separated by countercurrent contact extraction. The material at the top of the extraction separation tower is separated from the extraction solvent to obtain isotropic pitch. The extraction solvent is selected from one of n-pentane, n-heptane, cyclohexane, benzene, toluene, xylene, ethylbenzene or tetrahydrofuran, and the volume ratio of solvent to oil is 1~20. The extraction temperature is 300~360℃ and the extraction pressure is 2.0~6.0MPa. (5) After the heavier asphalt components at the bottom of the extraction separation tower are separated from the extraction solvent, high softening point coated asphalt is obtained. The softening point of the high softening point coated asphalt is 220-280℃.

2. The preparation process of isotropic asphalt and high softening point coated asphalt according to claim 1, characterized in that, The residual carbon value of isotropic asphalt reaches 45-55%, and the softening point is 200-250℃; The residual carbon value of the high softening point coated bitumen is ≥70%, and the quinoline insoluble matter is ≤1%.

3. The preparation process of isotropic asphalt and high softening point coated asphalt according to claim 1, characterized in that, In step (3), the light components of oil and gas are condensed and recovered through a hot high-pressure separator and a cold low-pressure separator.

4. Isotropic asphalt and high softening point coated asphalt prepared by the process described in any one of claims 1-3.

Images