A high-capacity needle coke production process based on transitional layered stacking

Abstract

The invention discloses a production process of high-capacity needle coke mainly in transitional layered stacking, belongs to the technical field of high-capacity needle coke production for negative electrodes, and is characterized in that the high-capacity needle coke production process mainly in transitional layered stacking is prepared by using staged hydrogenation product oil as a raw material through an intermediate phase fusion process, an intermediate phase regrowth process, a rapid heating process and a raw coke stripping process; the beneficial effects of the invention are: a needle coke microstructure mainly in intermediate state stacking is obtained through the intermediate phase regrowth process, the intermediate phase length and width of the structure are both higher than 300μm, the unit cell volume is greater than 150 calculated by XRD unit cell volume, and it appears as a stacking structure under an electron microscope; the gram capacity can reach 362mAh / g, far exceeding 355mAh / g of the previous process, and at the same time, due to the adjustment of the process, the grinding output is increased from 300kg / h to 370kg / h, and both the output and gram capacity are greatly improved.

Description

Technical field:

[0001] The invention belongs to the technical field of production of high-capacity needle coke for negative electrodes, and in particular relates to a production process of high-capacity needle coke mainly based on transitional layered accumulation. Background technology:

[0002] As a new type of carbon material, needle coke has the characteristics of high capacity, good stability and adjustable structure. It is a high-quality raw material for producing high-performance negative electrode materials. The performance of needle coke determines the properties of the negative electrode materials.

[0003] Gram capacity, also known as specific capacity, is the most important indicator of needle coke for negative electrode and has great significance. There are many production processes for negative electrode, which can generally be divided into grinding, shaping, coating granulation, carbonization, graphitization and other processes. Each process can be adjusted and improved accordingly according to the needs of the negative electrode. The rate performance and high and low temperature performance of the negative electrode can be adjusted through subsequent processes, but the capacity of needle coke generally determines the capacity of the entire negative electrode. Therefore, high capacity can be said to be the most important indicator of needle coke for negative electrode.

[0004] At present, the capacity of industrialized needle coke in China and abroad can reach up to 358-360mAh / g, among which the theoretical upper limit of the capacity of graphite material is 372mAh / g. Some reports exceed this limit. This is because there are different detection methods and it is meaningless to compare.

[0005] However, the generally recognized detection method in this field is GBT 24533-2009 lithium-ion battery graphite negative electrode materials. The specific capacity of a type of needle coke of graphite negative electrode materials detected by this method is greater than 355mAh / g, and 360mAh / g is the specific capacity ceiling of needle coke in actual industrial production. It is difficult to exceed 360mAh / g for needle coke obtained by testing according to GBT24533-2009 lithium-ion battery graphite negative electrode materials.

[0006] Currently, the most commonly used method is to adjust the temperature and reaction time of the coke production and coke pulling processes to obtain different needle cokes. The specific capacity of needle coke obtained using GBT 24533-2009 lithium-ion battery graphite negative electrode materials cannot exceed the bottleneck of 360mAh / g no matter how it is optimized. Summary of the invention:

[0007] In order to solve the above problems and overcome the shortcomings of the prior art, the present invention provides a production process of needle coke mainly based on transitional layered stacking, which can obtain high-capacity needle coke.

[0008] The specific technical solution of the present invention to solve the above technical problems is: a high-capacity needle coke production process based on transitional layered stacking, characterized in that the high-capacity needle coke is prepared by using staged hydrogenation product oil as raw material through an intermediate phase fusion process, an intermediate phase regrowth process, a rapid heating process and a raw coke stripping process;

[0009] The intermediate phase fusion process: the heating furnace is heated to 430-470°C to add staged hydrogenation product oil, and the circulating oil is added at the same time, the circulation ratio is 1:1-1:2, and the pressure is 0.5-1MPa;

[0010] The intermediate phase regrowth process: after 8 hours of constant temperature feeding, the circulation ratio is reduced to 0.5:1, and the pressure is increased to 1-1.5MPa;

[0011] The rapid heating process: heating to 470-550°C after 12 hours, with a heating rate of 10°C / h;

[0012] The coke stripping process is as follows: after 24 hours of coking, the feeding is stopped, the temperature is maintained for 3 hours, the temperature is raised to 500-600° C., and the stripping is performed for 12 hours.

[0013] Furthermore, the preparation of the segmented hydrogenation product oil comprises: cutting the hydrogenation feedstock oil into two distillation ranges of 300-430°C and above 430°C according to the distillation range, and hydrodesulfurizing the 300-430°C distillation range, decompressing the desulfurized hydrogenation product oil to remove a preset amount of light components, and then mixing it with the 430°C distillation range oil, and further mixing it with the furfural extraction oil at a ratio of 5:1-15:1, and evenly mixing to obtain the segmented hydrogenation product oil.

[0014] Furthermore, the intermediate phase regrowth process: after 8 hours of constant temperature feeding, the circulation ratio is reduced to 0.5:1, and the pressure is increased to 1-1.5MPa, and the pressure change operation is based on the formula P=1.727MPa-0.6336MPa×real-time circulation ratio-0.02507MPa×real-time coking feed value+0.01257MPa×internal and external temperature difference.

[0015] Furthermore, the coking feed rate is 2-20 kg / h.

[0016] Furthermore, the internal and external temperature difference is the difference between the internal temperature of the coke drum and the external wall temperature of the coke drum.

[0017] Furthermore, the ratio of the desulfurized hydrogenated product oil to remove a preset amount of light components is 3%-15% of the feed amount of the decompression device.

[0018] Furthermore, the furfural extraction oil is: the bottom oil extracted from the FCC oil slurry after furfural extraction, containing heavy aromatics and gum.

[0019] Furthermore, after the coke stripping process is completed, a coke cooling process and a coke removal process are also included.

[0020] Wherein: the above-mentioned circulating oil is the coke tower distillate oil of the coking raw oil at 0.1MPa and 430℃, which is a light wax oil.

[0021] The beneficial effects of the present invention are:

[0022] (1) The heavy aromatic macromolecules in the heavy distillation section can be retained by hydrogenation in the distillation section, and the aromatic heteroatoms in the hydrogen distillation section can be further removed. At the same time, the back-mixing of the extracted oil can increase the polycyclic aromatic hydrocarbons in the system, which plays a role as a skeleton in the coking process. The light components with low heteroatoms can promote their reaction to use the polycyclic aromatic hydrocarbon planar molecules as the skeleton and grow according to the planar stacking;

[0023] (2) A needle coke microstructure dominated by intermediate state stacking was obtained through the intermediate phase regrowth process. The length and width of the intermediate phase of this structure are both greater than 300 μm. The unit cell volume calculated by XRD is greater than 150, and it appears as a stacking structure under an electron microscope.

[0024] (3) The gram capacity of needle coke prepared is mainly in the intermediate state of stacking, and can reach 362 mAh / g, far exceeding the 355 mAh / g of the previous process. At the same time, due to the adjustment of the process, the grinding output is increased from 300 kg / h to 370 kg / h, and both the output and gram capacity are greatly improved. Description of the drawings:

[0025] Attached Figure 1 This is the needle focus polarizing microscope image of Example 1 of the present invention;

[0026] Attached Figure 2 This is the SEM image of needle coke in Example 1 of the present invention;

[0027] Attached Figure 3 This is the needle focus polarizing microscope image of Comparative Example 1 of the present invention;

[0028] Attached Figure 4 This is the needle focus polarizing microscope image of Comparative Example 2 of the present invention;

[0029] Attached Figure 5 This is the needle focus polarizing microscope image of Comparative Example 3 of the present invention;

[0030] Attached Figure 6 This is a needle focus polarizing microscope image of Comparative Example 4 of the present invention; in the accompanying drawings: Specific implementation method:

[0031] In the description of the present invention, specific details are only for a full understanding of the embodiments of the present invention, but those skilled in the art should know that the implementation of the present invention is not limited to these details. In addition, well-known structures and functions are not described or shown in detail to avoid blurring the key points of the embodiments of the present invention. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] Specific implementation of the present invention:

[0033] In order to better understand the present invention, a specific embodiment is used for illustration. It is worth emphasizing that the effect of this embodiment is not substantially different from the various embodiments within the protection scope of the present invention, including the respective reagents and the content ratio of the reagents, and all of them can achieve the effects described in the present invention and solve the above-mentioned problems. Other combinations are not described here.

[0034] Embodiment 1:

[0035] (1) Preparation of staged hydrogenation product oil:

[0036] The hydrogenated feedstock oil is cut into two distillation ranges of 300-430°C and above 430°C according to the distillation range, and the 300-430°C distillation range is hydrodesulfurized. After desulfurization, the hydrogenated product oil is decompressed to remove a preset amount of light components and then mixed with the 430°C distillation range oil, and further mixed with the furfural extraction oil at a ratio of 5:1-15:1, and the segmented hydrogenation product oil is obtained after uniform mixing, and the uniform mixing is placed in a coking feedstock tank.

[0037] The ratio of the desulfurized hydrogenated product oil to remove a preset amount of light components is 3-15% of the feed amount of the decompression device;

[0038] The furfural extraction oil is: the bottom oil extracted from the FCC slurry after furfural extraction, containing heavy aromatics and colloids;

[0039] (2) Intermediate phase fusion process:

[0040] The heating furnace is heated to 430-470℃ and the product oil is added in staged hydrogenation, and the circulating oil is added at the same time, with a circulation ratio of 1:1-1:2 and a pressure of 0.5-1MPa;

[0041] (3) Interphase regrowth process:

[0042] After 8 hours of constant temperature feeding, the circulation ratio is reduced to 0.5:1, and the pressure is increased to 1MPa-1.5MPa. The pressure is adjusted in real time by adjusting the pressure during the pressure increase process, wherein: the pressure change operation is based on the formula: P = 1.727MPa-0.6336MPa × real-time circulation ratio - 0.02507MPa × real-time coking feed value + 0.01257MPa × internal and external temperature difference.

[0043] The coking feed rate is: 2-20kg / h, and the internal and external temperature difference is the difference between the internal temperature of the coke drum and the external wall temperature of the coke drum;

[0044] (4) Rapid heating process:

[0045] After 12 hours, the temperature was raised to 470-550°C at a rate of 10°C / h.

[0046] (5) Coke stripping process:

[0047] After 24 hours of coking, the feeding is stopped, the temperature is maintained for 3 hours, the temperature is raised to 500-600°C, and the stripping is carried out for 12 hours. After the stripping is completed, cooling and decoking may also be included.

[0048] Wherein: the above-mentioned circulating oil is the coke tower distillate oil of the coking raw oil at 0.1MPa and 430℃, which is a light wax oil.

[0049] In order to more intuitively demonstrate the process advantages of the present invention, the high-capacity needle coke production process of the present invention based on transitional layered stacking is compared with the same process using an equivalent replacement method.

[0050] Comparative Example 1:

[0051] The preparation method is the same as that of Example 1, except that: in the preparation process of this comparative example, the raw material is hydrogenated raw oil;

[0052] Comparative Example 2:

[0053] The preparation method is the same as that of Example 1, except that: in the preparation process of this comparative example, the intermediate phase fusion process adopts: after constant temperature feeding for 8 hours, the circulation ratio is reduced to 0.5:1, and the pressure is increased to 1MPa-1.5MPa; wherein the pressure is increased by isogradient constant pressure, and the pressure change rate is: 0.1MPa / h;

[0054] And instead of using a rapid heating process, a slow heating process to 470-550°C was used, with a heating rate of 3°C / h;

[0055] Comparative Example 3:

[0056] The preparation method is the same as that of Example 1, except that: in the preparation process of this comparative example, the intermediate phase fusion process adopts: after constant temperature feeding for 8 hours, the circulation ratio is reduced to 0.5:1, and the pressure is increased to 1-1.5MPa; wherein the pressure is increased by isogradient constant pressure, and the pressure change rate is: 0.1MPa / h;

[0057] Comparative Example 4:

[0058] The preparation method is the same as that of Example 1, except that: in the preparation process of this comparative example, a rapid heating process is not used, but a slow heating process is used to 470-550°C, with a heating rate of 3°C / h;

[0059] Table 1: Comparison of needle coke production indicators in different processes

[0060]

[0061] According to the data analysis in Table 1:

[0062] (1) By comparing Example 1 with Comparative Example 1, it can be seen that the gram capacity of Example 1 is better than the gram capacity of Comparative Example 1;

[0063] This may be because the heavy aromatic macromolecules in the heavy distillation section can be retained by the segmented hydrogenation in the distillation section, and the aromatic heteroatoms in the hydrogen distillation section can be further removed. At the same time, the back-blending of the extracted oil can increase the polycyclic aromatic hydrocarbons in the system, which plays a role as a skeleton in the coking process and further increases the content of heavy aromatic hydrocarbon molecules. After the mixing is completed, the aromatic content accounts for 70%-90%, and the aromatics with more than 4 rings account for 20%-60%;

[0064] In this way, the removal of light components in the hydrogenated product oil can effectively reduce the effect of chain alkanes and light cycloalkanes on hindering the fusion. The light components with low heteroatoms can promote their reaction to take polycyclic aromatic hydrocarbons as the skeleton and grow according to the plane stacking, effectively reducing the formation of mosaic structure.

[0065] (2) Comparison between Example 1 and Comparative Example 3 shows that the gram capacity of Example 1 is slightly better than that of Comparative Example 3.

[0066] This is because: compared with the slow heating process, the rapid heating process can further accelerate the overflow of volatiles by changing the pressure and increasing the temperature after 12 hours, which can improve the morphology of the upper coke of the later feed to a certain extent, making it have a more uniform mesophase structure;

[0067] (3) By comparing Example 1, Comparative Example 2 and Comparative Example 4, it can be seen that:

[0068] The gram capacity of Example 1 is much greater than that of Comparative Example 2 and Comparative Example 4, and the gram capacity of Comparative Example 2 and Comparative Example 4 is not much different.

[0069] This may be because the real-time pressure adjustment method used in the intermediate phase regrowth process can well realize the formation of high-capacity needle coke dominated by transitional layered stacking. During the feeding process, the crude oil will undergo cracking and condensation under high temperature, and a large amount of light components will overflow, causing the system pressure to increase. These light components will overflow in the direction of lower pressure, thereby overflowing out of the raw material system, causing the system viscosity to increase and the intermediate phase to develop slowly. The real-time pressure adjustment method can effectively further suppress the light components in the system and reduce the increase in system viscosity caused by the condensation process. At the same time, the light components with low heteroatoms can promote their reaction to grow according to the planar stacking structure of polycyclic aromatic hydrocarbons with planar molecules as the skeleton.

[0070] The increase of system pressure is related to many factors, such as circulation ratio, coking feed amount and internal and external temperature difference. The above factors will lead to changes in system pressure. Only by effectively weighing the influence of the above factors on system pressure can the length and width of the intermediate phase obtained by the present invention be higher than 300 μm, the unit cell volume calculated by XRD unit cell volume is greater than 150, and it appears as a stacked structure under an electron microscope. Figure 1 and Figure 2 ;

[0071] The needle coke produced by this method uses GBT 24533-2009 lithium-ion battery graphite negative electrode material needle coke. The specific capacity (coke capacity) can reach 362mAh / g, surpassing the bottleneck of 360mAh / g and far exceeding the 355mAh / g of the previous process. It is close to its theoretical capacity of 372mAh / g, and its Hastelloy grindability can reach 92, which is an ultra-high capacity and easy-to-process coke. The grinding output is increased from 300kg / h to 370kg / h, and both the output and gram capacity are greatly improved.

[0072] (4) The small difference in gram capacity between Comparative Example 2 and Comparative Example 4 indicates that once the intermediate phase morphology has been finalized, it is difficult to significantly increase the gram capacity even through process adjustments such as the rapid heating step and the coke stripping step.

[0073] In summary: (1) The heavy aromatic macromolecules in the heavy distillation section can be retained by hydrogenation in the distillation section, and the aromatic heteroatoms in the hydrogen distillation section can be further removed. At the same time, the back-mixing of the extracted oil can increase the polycyclic aromatic hydrocarbons in the system, which plays a role as a skeleton in the coking process. The light components with low heteroatoms can promote their reaction to use the polycyclic aromatic hydrocarbon planar molecules as the skeleton and grow according to the planar stacking;

[0074] (2) A needle coke microstructure dominated by intermediate state stacking was obtained through the intermediate phase regrowth process. The length and width of the intermediate phase of this structure are both greater than 300 μm. The unit cell volume calculated by XRD is greater than 150, and it appears as a stacking structure under an electron microscope.

[0075] (3) The gram capacity of needle coke prepared is mainly in the intermediate state of stacking, and can reach 362 mAh / g, far exceeding the 355 mAh / g of the previous process. At the same time, due to the adjustment of the process, the grinding output is increased from 300 kg / h to 370 kg / h, and both the output and gram capacity are greatly improved.

Claims

1. A high-capacity needle coke production process based on transitional layered stacking, characterized in that The product is prepared by using the staged hydrogenation product oil as raw material through the intermediate phase fusion process, intermediate phase regrowth process, rapid heating process and coke stripping process; The preparation of the segmented hydrogenation product oil comprises: cutting the hydrogenation feedstock oil into two distillation ranges of 300-430°C and above 430°C according to the distillation range, and hydrodesulfurizing the distillation range of 300-430°C, decompressing the desulfurized hydrogenation product oil to remove a preset amount of light components, and then mixing it with the oil of the distillation range of 430°C, and further mixing it with the furfural extraction oil at a ratio of 5:1-15:1, and uniformly mixing to obtain the segmented hydrogenation product oil; The ratio of the preset amount of light components removed from the decompression product oil after desulfurization is 3%-15% of the feed amount of the decompression device. The furfural extraction oil is: the bottom oil extracted from the FCC oil slurry after furfural extraction, containing heavy aromatics and colloids; The intermediate phase fusion process: the heating furnace is heated to 430-470°C to add staged hydrogenation product oil, and the circulating oil is added at the same time, the circulation ratio is 1:1-1:2, and the pressure is 0.5-1MPa; The intermediate phase regrowth process: after constant temperature feeding for 8 hours, the circulation ratio is reduced to 0.5:1, and the pressure is increased to 1-1.5MPa by transformation. The transformation operation is based on the formula P=1.727MPa-0.6336MPa×real-time circulation ratio-0.02507MPa×real-time coking feed value+0.01257MPa×internal and external temperature difference, where the internal and external temperature difference is the difference between the internal temperature of the coke drum and the external wall temperature of the coke drum; The rapid heating process: heating to 470-550°C after 12 hours, with a heating rate of 10°C / h; The coke stripping process is as follows: after 24 hours of coking, the feeding is stopped, the temperature is maintained for 3 hours, the temperature is raised to 500-600° C., and the stripping is performed for 12 hours.

2. The high-capacity needle coke production process according to claim 1, characterized in that The coking feed rate is: 2-20kg / h.

3. The high-capacity needle coke production process according to claim 1, characterized in that The coke stripping process also includes a coke cooling process and a coke removal process.

4. The high-capacity needle coke production process according to claim 1, characterized in that The circulating oil is the coke tower distillate oil of the coking raw oil at 0.1 MPa and 430° C., and is a light wax oil.

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