Method for preparing spinnable mesophase pitch through ethylene tar thermal separation component cutting-thermal polycondensation
By combining a fixed-bed reactor and a vacuum distillation tower with a high-pressure reactor, the problem of removing highly reactive olefin components from ethylene tar was solved, and mesophase pitch with good spinnability was prepared, achieving efficient resource utilization and performance improvement.
Patent Information
- Application Number
- CN202510891975.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-30
- Publication Date
- 2025-11-04
AI Technical Summary
Existing technologies are insufficient to effectively remove highly reactive olefin components from ethylene tar, resulting in a high softening point in the mesophase pitch, which fails to meet the performance requirements of spinning raw materials.
Selective catalytic polymerization was carried out in a fixed-bed reactor, combined with vacuum distillation and high-pressure reactor treatment. The thermal separation and thermal polycondensation of ethylene tar were carried out by selective catalysts such as carbon nanotubes supported on nanoscale WO3, TiO2, and MoS2 to form spinnable mesophase pitch.
This method achieves efficient removal of olefin components from ethylene tar across the entire distillation range, producing mesophase pitch with a moderate softening point and excellent spinnability. The byproducts, light oil and gum components, can be used as other chemical raw materials, thus improving resource utilization.
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of high value-added application product development of ethylene tar, and particularly relates to a method for preparing spinnable mesophase pitch by cutting and thermal polycondensation of hot separation components of ethylene tar. BACKGROUND
[0002] Ethylene tar is mainly derived from the process of catalytic cracking of naphtha to produce ethylene. With the development of the ethylene industry, the global production of ethylene tar has exceeded 300 million tons by 2017. At present, ethylene tar is mainly used as boiler fuel or for the production of carbon black, which is of low economic efficiency and causes serious pollution. Therefore, it is of great significance to develop high value-added application products of ethylene tar for efficient utilization of resources.
[0003] Mesophase pitch as a spinning raw material requires low ash content, low heteroatom content, high carbon yield, excellent rheological properties and other performance characteristics. Due to its aromaticity, moderate H / C ratio, good solubility and low ash content, ethylene tar can be used as an ideal precursor for the production of high-grade carbon materials such as mesophase pitch, needle coke and isotropic coke. The main reason for limiting the application of ethylene tar in industrial production is that it is mainly composed of polycyclic aromatic hydrocarbons containing rich side chain groups, especially highly active olefin functional groups, which leads to high reactivity of ethylene tar during thermal treatment, resulting in rapid increase of system viscosity and hindering the normal development of mesophase. In order to solve this problem, researchers often need to pretreat ethylene tar to reduce the content of highly active olefin functional groups before developing carbon products from ethylene tar, so as to improve the subsequent pyrolysis process and obtain a wide-range mesophase.
[0004] The main pretreatment methods at present include hydrogenation treatment, co-carbonization, catalytic modification and component cutting. Mochida et al. improved the solubility of the product and the optical texture by hydrogenation treatment and AlCl3 catalytic modification of ethylene tar to some extent, but the hydrogenation treatment process has high operating cost and the AlCl3 catalyst is difficult to remove, resulting in high cost of the prepared mesophase pitch and difficulty in meeting the performance requirements of spinning raw materials. Cheng Xianglin et al. co-carbonized ethylene tar with waste polystyrene and further prepared needle coke. Ge Chuanchang et al. cut the components of ethylene tar by vacuum distillation, screened out heavy components with suitable thermal reactivity, and further prepared a wide-range mesophase pitch by thermal polymerization process, but due to the wide distillation range of olefin-containing components in ethylene tar, it is difficult to achieve ideal separation effect of heavy olefins (C8 and above) in ethylene tar by using a single distillation separation process, which leads to rapid polymerization of olefin-containing components in the heavy components during thermal polymerization, resulting in high softening point of the prepared mesophase pitch and still unable to meet the requirements of spinning raw materials.
[0005] In summary, how to realize the high-selectivity removal of full-range olefin components in ethylene tar, so as to optimize the composition and structure thereof, is a technical difficulty in the preparation of high-quality mesophase pitch and carbon materials therefrom using ethylene tar as a raw material, and is a key problem to be solved by those skilled in the art. SUMMARY
[0006] The present application aims to overcome the defects of the prior art, and provides a method for preparing spinnable mesophase pitch by cutting and thermal polycondensation of heat-separated components of ethylene tar, which efficiently removes full-range olefin components in ethylene tar, and thus realizes the preparation of mesophase pitch with moderate softening point, wide-area / wide-area flow-line optical texture and excellent spinnability.
[0007] The present application provides the following technical solutions:
[0008] The present application provides a method for preparing spinnable mesophase pitch by cutting and thermal polycondensation of heat-separated components of ethylene tar, which comprises the following steps:
[0009] S1, heating ethylene tar to 150-250 DEG C and then sending it to a fixed-bed reactor to perform polymerization treatment on the olefin components;
[0010] S2, sending the ethylene tar treated in step S1 into a vacuum distillation column to perform heat separation, wherein the overhead temperature of the vacuum distillation column is 250-300 DEG C, light oil is removed at the overhead, the bottom temperature is 450-520 DEG C, and gum components are removed at the bottom;
[0011] S3, sending the fraction obtained by removing the overhead and bottom materials in the vacuum distillation column into a high-pressure reaction kettle to perform autogenous pressure reaction;
[0012] S4, after the reaction is completed, performing vacuum distillation on the reaction product, and then cooling to obtain the spinnable mesophase pitch.
[0013] In the present application, ethylene tar is first subjected to selective catalytic polymerization in a fixed-bed reactor, and then subjected to heat separation in a vacuum distillation column, wherein the high-reactivity olefin components are converted into gum components (boiling point > 450 DEG C) by selective catalytic polymerization in the fixed-bed reactor, and are removed from the bottom of the distillation column as by-products, and the fraction with a boiling point < 300 DEG C in the ethylene tar is removed from the overhead line as by-products; the remaining fraction contains very little olefin components, and is converted into mesophase pitch by autogenous pressure polymerization, and then is subjected to vacuum distillation to obtain the spinnable mesophase pitch.
[0014] Further, the ash content of the ethylene tar is less than 200 ppm, the molecular weight distribution is 100-1000, and the content of the olefin components is 2-10%.
[0015] Further, in step S1, a selective catalyst bed is arranged in the fixed bed reactor, and the selective catalyst is carbon nanotube loaded with one or more of nanoscale WO3, TiO2 and MoS2, wherein the loading amount of the metal oxide or sulfide is 0.5-10.0%.
[0016] Further, in step S2, the operating pressure of the vacuum distillation column is -0.095-0 MPa, and nitrogen gas is continuously fed during the process, with a flow rate of 1-5 L / (min·Kg).
[0017] Further, in step S2, the overhead temperature of the vacuum distillation column is 250-300℃, the bottom temperature is 450-520℃, the olefin content of the light oil removed at the overhead is 3-17%, and the olefin content of the gum component removed at the bottom is 5-18%.
[0018] Further, in step S3, the olefin content in the fraction is <1.0%, the temperature in the high-pressure reaction kettle is 370-450℃, the pressure during the reaction is 0.5-8 MPa, and the reaction time is 1-12 h.
[0019] Further, the stirring in the high-pressure reaction kettle is continuously kept on, and the stirring rate is 10-1000 r / min.
[0020] Further, in step S4, the vacuum distillation is performed at 370-440℃, 3-10 L / (min·Kg) of nitrogen gas flow and -0.05--0.09 MPa.
[0021] The application also provides a spinnable mesophase pitch prepared by the above method, which has a softening point of 270-290℃, a mesophase content of 85-100%, and a H / C molar ratio of 0.50-0.60.
[0022] The spinnable mesophase pitch can be melt-spun to prepare continuous filaments with a length of more than 3000 m and a diameter of 12-18 μm.
[0023] The application has the following beneficial effects:
[0024] 1. The application can remove the olefin components in the full distillation range of the ethylene tar, and the olefin content in the treated ethylene tar fraction is lower than 1.0%, realizing the preparation of a spinnable mesophase pitch using ethylene tar as the raw material.
[0025] 2. The byproduct light oil produced by the application can be used as a raw material for a catalytic cracking device to produce gasoline and diesel oil, and the gum component can be used as a binder pitch, realizing the effective utilization of different components of the ethylene tar and improving the added value, and the production process of the application has relatively mild reaction conditions and is easy to realize industrialization and popularization. DETAILED DESCRIPTION
[0026] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the protection scope of the present application.
[0027] Embodiment 1
[0028] The method for preparing the spinnable mesophase pitch by cutting and thermal polycondensation of the thermal separation component of ethylene tar in the embodiment is specifically as follows:
[0029] 1. The ethylene tar with ash content of 100 ppm and olefin component content of 8.1% is heated to 200°C by a heating furnace and then pumped into a fixed bed reactor. The operating temperature of the fixed bed reactor is 250°C, the pressure is 3.0 MPa, and the used selective catalyst is carbon nanotube loaded with 5% nanometer WO3. The olefin component in the ethylene tar preferentially occurs polymerization reaction when flowing through the bed of the selective catalyst to form a gum component.
[0030] 2. The ethylene tar treated by the fixed bed is pumped into a vacuum distillation column. The operating pressure of the vacuum distillation column is-0.095 MPa, the overhead temperature is 300°C, the bottom temperature is 500°C, and the nitrogen gas flow rate is 2 L / (min·Kg). The light oil is collected from the overhead line, and the gum component is discharged from the bottom of the distillation column.
[0031] 3. The 300-500°C fraction remaining in the vacuum distillation column is collected by a pipeline and then pumped into a stainless steel autoclave to continue heating to 430°C for 5 h under autogenous pressure. The pressure during the reaction process is 3 MPa.
[0032] 4. After the end of the autogenous pressure reaction, the vacuum distillation is continued at 380°C, 3 L / (min·Kg) of nitrogen gas flow and-0.06 MPa for 1 h. The spinnable mesophase pitch is obtained after cooling. The stirring is kept on during the operation of the reaction kettle, and the stirring rate is 1000 r / min.
[0033] It is detected that the olefin content of the light oil collected from the overhead of the vacuum distillation column is 16.0%, the olefin content of the gum component discharged from the bottom of the distillation column is 15.2%, and the olefin content of the fraction before entering the reaction kettle is 0.8%. Both of them are sold as by-products.
[0034] The prepared mesophase pitch has a softening point of 286°C, a mesophase content of 95%, and a H / C molar ratio of 0.55. The continuous spinnable filament is 5200 m, and the average filament diameter is 15 μm after subsequent melt spinning.
[0035] Example 2
[0036] The method for preparing the spinnable mesophase pitch by cutting and thermal polycondensation of the thermal separation components of ethylene tar in this example is as follows:
[0037] 1. The ethylene tar with ash content of 100 ppm and olefin component content of 8.1% was heated to 200°C by a heating furnace and then pumped into a fixed bed reactor. The operating temperature of the fixed bed reactor was 250°C, the pressure was 3.0 MPa, and the selected catalyst used was carbon nanotubes loaded with 8% nanoscale WO3. The olefin component in the ethylene tar preferentially underwent polymerization reaction when flowing through the bed of the selected catalyst, forming a gum component.
[0038] 2. The ethylene tar treated by the fixed bed was pumped into a vacuum distillation column. The operating pressure of the vacuum distillation column was -0.095 MPa, the overhead temperature was 300°C, the bottom temperature was 500°C, and the nitrogen gas flow rate was 2 L / (min·Kg). The light oil was collected from the overhead line, and the gum component was discharged from the bottom of the distillation column.
[0039] 3. The 300-500°C fraction remaining in the vacuum distillation column was collected by a pipeline and then pumped into a stainless steel autoclave, which was further heated to 430°C for 5 h under autogenous pressure. The pressure during the reaction was 3 MPa.
[0040] 4. After the end of the autogenous pressure reaction, the vacuum distillation was continued at 380°C, 3 L / (min·Kg) of nitrogen gas flow rate, and -0.06 MPa for 1 h. After the vacuum distillation was completed, the spinnable mesophase pitch was obtained by cooling. The stirring was kept on during the operation of the reaction kettle, and the stirring rate was 1000 r / min.
[0041] It was detected that the olefin content of the light oil collected from the overhead of the vacuum distillation column was 16.9%, the olefin content of the gum component discharged from the bottom of the distillation column was 17.2%, both of which were sold as by-products, and the olefin content in the fraction before entering the reaction kettle was 0.4%.
[0042] The prepared mesophase pitch had a softening point of 282°C, a mesophase content of 97%, and a H / C molar ratio of 0.55. The continuous spinnable filament length was 6000 m, and the average filament diameter was 12 μm after subsequent melt spinning.
[0043] Example 3
[0044] The method for preparing the spinnable mesophase pitch by cutting and thermal polycondensation of the thermal separation components of ethylene tar in this example is as follows:
[0045] 1. The ethylene tar with ash content of 100 ppm and olefin component content of 8.1% is heated to 200°C by a heating furnace and then pumped into a fixed bed reactor. The operating temperature of the fixed bed reactor is 250°C, the pressure is 3.0 MPa, and the selective catalyst used is 8% nanometer WO3 carbon nanotube. The olefin component in the ethylene tar preferentially undergoes polymerization reaction when flowing through the selective catalyst bed to form a gum component.
[0046] 2. The ethylene tar treated by the fixed bed is pumped into a vacuum distillation column. The operating pressure of the vacuum distillation column is -0.095 MPa, the overhead temperature is 250°C, the bottom temperature is 520°C, and the nitrogen gas flow rate is 2 L / (min·Kg). The light oil is collected from the overhead line, and the gum component is discharged from the bottom of the distillation column.
[0047] 3. The 250-520°C fraction remaining in the vacuum distillation column is collected by a pipeline and then pumped into a stainless steel autoclave for self-pressure reaction at 430°C for 5 h. The pressure during the reaction is 1 MPa.
[0048] 4. After the self-pressure reaction, the vacuum distillation is continued at 380°C, 3 L / (min·Kg) of nitrogen gas flow, and -0.06 MPa for 1 h. After the vacuum distillation is completed, the temperature is lowered to obtain a spinnable mesophase pitch. The stirring is kept on during the operation of the reaction kettle with a stirring rate of 500 r / min.
[0049] The detection shows that the olefin content of the light oil collected from the overhead of the vacuum distillation column is 14.3%, the olefin content of the gum component discharged from the bottom of the distillation column is 12.1%, both of which are sold as by-products, and the olefin content in the fraction before entering the reaction kettle is 0.5%.
[0050] The prepared mesophase pitch has a softening point of 290°C, a mesophase content of 95%, and a H / C molar ratio of 0.55. The subsequent melt spinning can continuously spin filaments with a length of 5000 m and an average filament diameter of 15 μm.
[0051] Example 4
[0052] In this example, the method for preparing a spinnable mesophase pitch by thermal separation component cutting and thermal polycondensation of ethylene tar is as follows:
[0053] 1. The ethylene tar with ash content of 100 ppm and olefin component content of 5.0% is heated to 200°C by a heating furnace and then pumped into a fixed bed reactor. The operating temperature of the fixed bed reactor is 250°C, the pressure is 3.0 MPa, and the selective catalyst used is 8% nanometer WO3 carbon nanotube. The olefin component in the ethylene tar preferentially undergoes polymerization reaction when flowing through the selective catalyst bed to form a gum component.
[0054] 2、The ethylene tar treated by the fixed bed is pumped into the vacuum distillation column, the operating pressure of the vacuum distillation column is -0.095 MPa, the top temperature is 250℃, the bottom temperature is 520℃, the nitrogen gas flow is 2 L / (min·Kg), the light oil is collected from the top pipeline, and the gum component is discharged from the bottom of the distillation column.
[0055] 3、The 250-520℃ fraction remaining in the vacuum distillation column is collected by pipeline and then pumped into a stainless steel autoclave, and then the temperature is increased to 430℃ for 5h autogenous pressure reaction, and the pressure during the reaction is 1 MPa.
[0056] 4、After the autogenous pressure reaction, vacuum distillation is continued at 380℃, 3 L / (min·Kg) nitrogen gas flow and -0.06 MPa for 1h, and then the temperature is decreased to obtain the spinnable mesophase pitch, and the stirring is kept on during the operation of the reactor with a stirring rate of 500 r / min.
[0057] The olefin content of the light oil collected from the top of the vacuum distillation column is 11.3%, the olefin content of the gum component discharged from the bottom of the distillation column is 10.1%, both of which are sold as by-products, and the olefin content in the fraction before entering the reactor is 0.3%;
[0058] The prepared mesophase pitch has a softening point of 290℃, a mesophase content of 99%, and a H / C molar ratio of 0.55, and the subsequent melt spinning can continuously spin filaments of 5000 m with an average filament diameter of 13 μm.
[0059] Comparative Example 1
[0060] The specific process in the comparative example is as follows:
[0061] 1、The ethylene tar with an ash content of 100 ppm and an olefin component content of 8.1% is heated to 200℃ by a heating furnace and then pumped into a vacuum distillation column, the operating pressure of the vacuum distillation column is -0.095 MPa, the top temperature is 300℃, the bottom temperature is 500℃, the nitrogen gas flow is 2 L / (min·Kg), the light oil is collected from the top pipeline, and the gum component is discharged from the bottom of the distillation column;
[0062] 2、The 300-500℃ fraction remaining in the vacuum distillation column is collected by pipeline and then pumped into a stainless steel autoclave, and then the temperature is increased to 430℃ for 5h autogenous pressure reaction, and the pressure during the reaction is 3 MPa, and then vacuum distillation is continued at 380℃, 3 L / (min·Kg) nitrogen gas flow and -0.06 MPa for 1h, and then the temperature is decreased to obtain the spinnable mesophase pitch, and the stirring is kept on during the operation of the reactor with a stirring rate of 1000 r / min.
[0063] The detected olefin content of the light oil taken from the top of the reduced pressure distillation column is 15.0%, the olefin content of the gum component discharged from the bottom is 9.5%, and the olefin content of the fraction before entering the reaction kettle is 5.0%;
[0064] The prepared mesophase pitch has a softening point of 305 DEG C, a mesophase content of 87%, and a H / C molar ratio of 0.54, and the mesophase pitch has poor spinnability and cannot be continuously spun.
[0065] The present application aims at the problems of high softening point, poor optical texture and inability to meet the performance requirements as a spinning raw material of the mesophase pitch prepared by using ethylene tar as raw material, and proposes a method of preparing spinnable mesophase pitch by cutting and thermal polycondensation of the hot separation components of ethylene tar, realizes the removal of olefin components in the whole distillation range of ethylene tar, and the olefin content of the treated ethylene tar fraction is less than 1.0%, realizing the preparation of spinnable mesophase pitch by using ethylene tar as raw material.
[0066] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims
1. A method for preparing spinnable mesophase pitch by thermal separation and thermal polycondensation of ethylene tar components, characterized in that, Includes the following steps: S1. Ethylene tar is heated to 150-250°C and then sent to a fixed-bed reactor to polymerize the olefin components. S2. The ethylene tar processed in step S1 is fed into a vacuum distillation column for thermal separation. The top temperature of the vacuum distillation column is 250-300℃, and light oil is removed from the top of the column. The bottom temperature is 450-520℃, and gum components are removed from the bottom of the column. S3. The fraction after removing the top and bottom substances from the vacuum distillation column is sent to a high-pressure reactor for autogenous pressure reaction. S4. After the reaction is complete, the product is subjected to vacuum distillation. After vacuum distillation, the product is cooled to obtain the spinnable mesophase pitch.
2. The method for preparing spinnable mesophase pitch by thermal separation and thermal polycondensation of ethylene tar components as described in claim 1, characterized in that: The ethylene tar has an ash content of less than 200 ppm, a molecular weight distribution of 100–1000, and an olefin content of 2–10%.
3. The method for preparing spinnable mesophase pitch by thermal separation and thermal polycondensation of ethylene tar components as described in claim 2, characterized in that: In step S1, the fixed-bed reactor is provided with a selective catalyst bed, and the selective catalyst is one or more of the following carbon nanotubes supported on nanoscale WO3, TiO2, and MoS2, wherein the loading of metal oxides or sulfides is 0.5 to 10.0%.
4. The method for preparing spinnable mesophase pitch by thermal separation and thermal polycondensation of ethylene tar components as described in claim 1, characterized in that: In step S2, the operating pressure of the vacuum distillation column is -0.095 to 0 MPa, and nitrogen gas is continuously introduced during the process at a flow rate of 1 to 5 L / (min·Kg).
5. The method for preparing spinnable mesophase pitch by thermal separation and thermal polycondensation of ethylene tar components as described in claim 4, characterized in that: In step S2, the olefin content of the light oil removed from the top of the tower is 3-17%, and the olefin content of the gum component removed from the bottom of the tower is 5-18%.
6. The method for preparing spinnable mesophase pitch by thermal separation and thermal polycondensation of ethylene tar components as described in claim 1, characterized in that: In step S3, the olefin content in the fraction is <1.0%, the temperature in the high-pressure reactor is 370-450℃, the pressure during the reaction is 0.5-8MPa, and the reaction time is 1-12h.
7. The method for preparing spinnable mesophase pitch by thermal separation and thermal polycondensation of ethylene tar components as described in claim 1, characterized in that: In step S4, the vacuum distillation is carried out at 370–440°C, with a nitrogen flow rate of 3–10 L / (min·Kg) and a pressure of -0.05–-0.09 MPa.
8. The method for preparing spinnable mesophase pitch by thermal separation and thermal polycondensation of ethylene tar components as described in claim 6 or 7, characterized in that: The stirring in the high-pressure reactor is kept running continuously at a speed of 10–1000 r / min.
9. The spinnable mesophase pitch prepared by the method according to any one of claims 1 to 8, characterized in that, The softening point of the spinnable mesophase pitch is 270–290℃, the mesophase content is 85–100%, and the H / C molar fraction ratio is 0.50–0.60.