CN110408434B

CN110408434B - Method for producing needle coke and BTX from coal tar whole fraction

Info

Publication number: CN110408434B
Application number: CN201810391998.0A
Authority: CN
Inventors: 梁家林; 吴昊; 李猛; 戴立顺; 胡志海
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2018-04-27
Filing date: 2018-04-27
Publication date: 2021-03-12
Anticipated expiration: 2038-04-27
Also published as: CN110408434A

Abstract

The invention relates to the field of coal chemical industry, and discloses a method for producing needle coke and BTX from coal tar whole fraction, which comprises the following steps: cutting the whole fraction of the coal tar into a coal tar light component and a coal tar heavy component; and (2) allowing the light components of the coal tar to enter a hydrogenation unit for reaction, separating clarified oil of the heavy components of the coal tar to obtain a raw material for producing needle coke, preparing a needle coke product through delayed coking and calcining processes, and extracting the light components of the coal tar rich in BTX through aromatic hydrocarbon to obtain the BTX product. By using the method of the invention, needle coke products and BTX chemical raw materials with low thermal expansion coefficients can be produced.

Description

Method for producing needle coke and BTX from coal tar whole fraction

Technical Field

The invention relates to the field of coal chemical industry, in particular to a method for producing needle coke and BTX from coal tar whole fraction.

Background

Coal is an important fossil energy source in China, and accounts for a high percentage in the primary energy consumption result in China. China experiences 30 years of rapid economic development, and the consumption of coal resources is rapidly increased. In recent years, the economic growth rate of China is gradually reduced, and the medium-high growth rate is maintained for a long time, so that the subsequent transformation and upgrade of industry are a problem facing the economy of China. Clean, environment-friendly and efficient utilization of coal resources is a necessary trend in the development of the coal industry in China. The classified utilization of coal is a development direction vigorously advocated in recent years in China, and the aim is to efficiently utilize coal resources. The key link of the coal grading utilization is the scheme of coal pyrolysis and subsequent product processing, wherein the deep processing of coal tar products from the coal pyrolysis to produce high-value products is one of core technologies of the coal grading utilization.

At present, coal tar is mainly used for producing bulk transportation fuels such as gasoline and diesel, however, with the long-term maintenance of petroleum price at 40-60 U.S. dollars/barrel, the economic type of the processing scheme for producing transportation fuels by hydrogenation of coal tar is increasingly reduced, and particularly, the processing scheme for producing gasoline and diesel products by cutting fractions of coal tar is basically maintained on a profit-loss balance line. Therefore, the production of higher value products from coal tar is a key step in the staged utilization of coal.

Needle coke is a raw material for manufacturing high-power and ultrahigh-power electrodes, and a graphite electrode prepared by adopting the needle coke has the advantages of low thermal expansion coefficient, high mechanical strength, small oxidation performance and the like. At present, needle coke which can be produced in China is petroleum-based needle coke, and the production of the coal-based needle coke is not reported yet. The technology for producing high-power electrodes by using needle coke is available in China, but needle coke raw materials still need to be imported in large quantity. Therefore, the production of needle coke from coal tar has a wide market prospect.

At present, domestic coal tar processing enterprises mainly carry out hydrogenation process treatment on medium-low temperature coal tar to prepare diesel products and a small amount of naphtha products, and the diesel products face the situation of supply and demand in China, so the economical efficiency of the processing process is poor. The heavy components of the medium and low temperature coal tar have the characteristics of high residual carbon content and high asphaltene colloid content, and the untreated heavy components of the medium and low temperature coal tar cannot be directly used as raw materials for producing needle coke, so that an enterprise cannot easily have a proper process to treat the heavy components.

CN103013566A discloses a process for producing needle coke raw material by using coal tar pitch, which comprises the steps of mixing pitch and a solvent fully, removing most quinoline insoluble substances in the pitch raw material, and carrying out hydrogenation thermal decomposition on the pitch with low quinoline insoluble substances to obtain the raw material for preparing the needle coke. The solvent in this process is a mixture of BTX or coal-based aromatics. The method has no organic combination and product property characteristics after processing of coal tar light fraction.

CN103509572A discloses a process for preparing high-quality coal-based needle coke by using a solvent method, which comprises the steps of mixing and uniformly stirring a coal-based raw material and a solvent, and removing insoluble substances of the solvent by using a physical separation method to obtain a clarified liquid, wherein the solvent comprises hydrocarbons of a coal tar distillate at 200-350 ℃ or a coal tar distillate at 200-300 ℃ after hydrogenation. The method utilizes the coal tar distillate section rich in aromatic hydrocarbon as a solvent, but does not fully utilize the property characteristics of the coal tar light distillate to produce high-value products.

CN101538482B discloses a method for further processing medium and low temperature coal tar, which comprises the steps of pretreating the medium and low temperature coal tar, fractionating the pretreated medium and low temperature coal tar to obtain light fraction, phenol oil and heavy fraction, coking the heavy fraction to obtain coked gasoline and diesel, mixing the coked gasoline and diesel with the light fraction to be used as raw materials for hydrorefining and hydrocracking, and catalytically reforming the hydrocracked naphtha to obtain chemical raw materials such as BTX and the like by using an aromatic drawer. The method has complex flow and cannot fully utilize the heavy fraction in the coal tar, so the process has poor economy.

CN106782979A discloses a process for preparing needle coke by using medium-low temperature coal tar and high-temperature pitch. According to the process, the heavy fraction of the medium-low temperature coal tar at the temperature of more than 350 ℃ is subjected to a hydro-pyrolysis reaction, and the generated heavy fraction obtained by centrifugal separation of the generated heavy component can be used as a raw material for producing needle coke. The process reduces quinoline insoluble substances in the raw materials through hydrogenation reaction, the investment cost of the device is high, the heavy fraction of the hydrogenation reaction needs to remove the solid catalyst in the heavy fraction through a centrifugal separation method, the process is complex, and the light components of medium-low temperature coal tar are not fully utilized.

Disclosure of Invention

The invention aims to provide a method for producing needle coke and BTX (benzene, toluene and xylene) by using a coal tar whole fraction raw material.

In order to achieve the above object, the method includes:

a method for producing needle coke and BTX from coal tar whole fraction, the method comprising:

(1) after pretreatment, cutting the coal tar full-fraction raw material into a coal tar light component and a coal tar heavy component, wherein the cutting point of the coal tar light component and the coal tar heavy component is 350-400 ℃;

(2) the light components of the coal tar enter a hydrogenation unit and contact with a hydrocracking catalyst to react, and the reaction effluent is separated and fractionated to obtain hydrogenated light naphtha, hydrogenated heavy naphtha and hydrogenated diesel oil;

(3) mixing the coal tar heavy component obtained in the step (1) with the hydrogenated heavy naphtha obtained in the step (2) to obtain clear liquid and insoluble substances;

(4) separating the clarified liquid obtained in the step (3) to obtain a fraction I and a fraction II;

(5) the fraction II obtained in the step (4) is a heavy component of coal tar containing low quinoline insoluble substances, and needle coke products are obtained through delayed coking and calcining processes of the fraction II;

(6) and (4) the fraction I obtained in the step (3) is a coal tar light component rich in BTX, and the BTX product is obtained after the fraction I is subjected to aromatic extraction.

The method provided by the invention combines the molecular characteristics of different components of the coal tar, fully utilizes the components in the light component and the heavy component, namely converts aromatic hydrocarbon in the light component of the coal tar into a high-value BTX product, and converts polycyclic aromatic hydrocarbon in the heavy component of the coal tar into a high-value needle coke product, thereby realizing the maximization of the utilization efficiency and the maximization of economic benefit of the whole fraction raw material of the coal tar.

Detailed Description

The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

The invention aims to provide a process for producing chemical materials such as needle coke, BTX and the like by coal tar whole fraction, which comprises the following steps:

In the invention, the pretreatment process of the coal tar whole fraction raw material comprises but is not limited to a boiling bed hydrogenation process, a slurry bed hydrogenation process or other pretreatment processes, and the main purpose is to remove most of impurities such as metal, ash and the like in the coal tar whole fraction raw material. Preferably, the content of metals in the pretreated coal tar whole fraction raw material is less than 50 mu g/g, the content of water is less than 300 mu g/g, and the content of ash is less than 0.01%.

In the invention, the coal tar whole fraction raw material is pretreated and then cut into the coal tar light component and the coal tar heavy component, and the preferable cutting point of the coal tar light component and the coal tar heavy component is 360-390 ℃.

In one embodiment of the present invention, the hydrogenation unit is fixed bed hydrocrackingA unit or a slurry bed hydrocracking unit or an ebullated bed hydrocracking unit. Preferred reaction conditions for the hydrogenation unit include: the reaction pressure is 6-30 MPa, the reaction temperature is 320-490 ℃, and the liquid hourly space velocity is 0.1-5.0 h^-1The volume ratio of hydrogen to oil is 200-2000.

In the present invention, the hydrogenation unit is preferably a fixed bed hydrocracking unit. The fixed bed hydrocracking unit is a one-section fixed bed hydrocracking process or a two-section fixed bed hydrocracking process. Preferably, the reaction conditions of the fixed bed hydrocracking unit include: the reaction pressure is 10-13 MPa, the reaction temperature is 350-410 ℃, and the liquid hourly space velocity is 0.5-2.0 h^-1The volume ratio of hydrogen to oil is 800-1500.

Preferably, the fixed bed hydrocracking unit is filled with a hydrofining catalyst and a hydrocracking catalyst, and the filling ratio of the hydrofining catalyst to the hydrocracking catalyst is 2: 8-8: 2. and (3) after the coal tar light component is contacted with a hydrofining catalyst, removing heteroatoms such as sulfur, nitrogen and metal in the coal tar light component, and saturating part of aromatic hydrocarbons. Then, the catalyst contacts with a hydrocracking catalyst to carry out hydrocracking reaction to generate dry gas, liquefied gas, hydrogenated light naphtha, hydrogenated heavy naphtha and hydrogenated diesel.

Preferably, the hydrofining catalyst comprises a carrier and an active metal element loaded on the carrier, wherein the carrier is selected from at least one of alumina, alumina-silica and titania, and the active metal element is selected from at least one of nickel, cobalt, molybdenum and tungsten; further preferably, in the hydrorefining catalyst, the content of nickel and/or cobalt in terms of oxide is 1 to 30% by weight, and the content of molybdenum and/or tungsten in terms of oxide is 5 to 35% by weight, based on the total weight of the hydrorefining catalyst.

Preferably, the hydrocracking catalyst comprises a carrier and an active metal element loaded on the carrier, wherein the carrier comprises a molecular sieve and at least one of alumina, alumina-silica and titania, and the active metal element is at least one of nickel, cobalt, molybdenum and tungsten; of the hydrocracking catalystThe bulk density is 0.4 to 1.3g/cm³The average particle diameter of the hydrocracking catalyst is 0.08-1.2 mm, and the specific surface area is 100-300 m²(ii)/g; further preferably, in the hydrocracking catalyst, the content of the molecular sieve is 10 to 60 wt%, the content of nickel and/or cobalt calculated as oxide is 1 to 30 wt%, and the content of molybdenum and/or tungsten calculated as oxide is 5 to 40 wt%, based on the total weight of the hydrocracking catalyst.

In the invention, the reaction effluent of the hydrogenation unit in the step (2) is separated and fractionated to obtain hydrogenated light naphtha, hydrogenated heavy naphtha and hydrogenated diesel oil, preferably, the cutting point between the hydrogenated light naphtha and the hydrogenated heavy naphtha is 65-80 ℃, and the cutting point between the hydrogenated heavy naphtha and the hydrogenated diesel oil is 175-190 ℃; wherein the yield of the hydrogenated light naphtha is 10-20%, the yield of the hydrogenated heavy naphtha is 15-70%, and the yield of the hydrogenated diesel oil is 5-10%.

Preferably, the hydrogenated diesel oil is recycled to the inlet of the hydrogenation unit to continue the reaction, and hydrogenated heavy naphtha is further generated.

In step (3) of the invention, the coal tar heavy component obtained in step (1) is mixed with the hydrogenated heavy naphtha obtained in step (2) to obtain clear liquid and insoluble substances. Wherein the insoluble fraction is essentially quinoline insoluble. Preferably, the mass ratio of the coal tar heavy components to the hydrogenated heavy naphtha is 0.1-10, and more preferably 2-5.

Preferably, the temperature of the mixing of the coal tar heavy components and the hydrogenated heavy naphtha in the step (3) is 40 ℃ to 120 ℃, and more preferably 60 ℃ to 90 ℃.

In step (4) of the present invention, the clarified liquid obtained in step (3) is subjected to a separation process to obtain fraction I and fraction II. Preferably, the separation process in step (4) is a physical separation method, the physical separation method includes a distillation method, a centrifugal separation method and other separation methods, and the centrifugal separation method is more preferred.

In the invention, the obtained fraction II is a heavy component of coal tar containing low quinoline insoluble substances, and a needle coke product is obtained by the delayed coking and calcining processes of the fraction II; the delayed coking and calcining process is a conventional process for producing needle coke.

In the invention, the fraction I obtained in the step (3) is a coal tar light component rich in BTX, and the BTX product is obtained after the fraction I is subjected to aromatic extraction. The aromatic extraction is a conventional aromatic extraction process.

According to the invention, aiming at the molecular characteristics of different components of the coal tar, the components in the light component and the heavy component are fully utilized, namely, aromatic hydrocarbons in the light component of the coal tar are converted into a high-value BTX product, and polycyclic aromatic hydrocarbon components in the heavy component of the coal tar are converted into a high-value needle coke product, so that the utilization efficiency maximization and the economic benefit maximization of the whole fraction raw material of the coal tar are realized.

The invention will now be further described by way of the following examples, but is not limited thereto.

Example 1

The medium and low temperature coal tar whole fraction raw material is pretreated, and the properties of the medium and low temperature coal tar whole fraction are shown in table 1. In the pretreated coal tar whole fraction raw material, the metal content is 30 mug/g, the water content is 100 mug/g, and the ash content is 0.005%.

And cutting the pretreated coal tar full-fraction raw material into a coal tar light component and a coal tar heavy component through a fractionating tower, wherein the cutting point of the coal tar light component and the coal tar heavy component is 370 ℃.

And (3) allowing the obtained coal tar light components to enter a hydrogenation unit, wherein the hydrogenation unit is a fixed bed hydrocracking unit, and a hydrofining catalyst and a hydrocracking catalyst are sequentially filled in the hydrogenation unit, and the filling volume ratio of the hydrofining catalyst to the hydrocracking catalyst is 1: 1. The hydrofining catalyst consists of NiMoW/Al₂O₃The hydrocracking catalyst consists of NiMoW/Al₂O₃/SiO₂Wherein the mass content of the molecular sieve is 27 percent, and the reaction conditions of the fixed bed hydrocracking unit comprise: the reaction pressure is 10.0MPa, the hydrofining reaction temperature is 370 ℃, the hydrocracking reaction temperature is 370 ℃, and the volume space velocity is 1.5h^-1The volume ratio of hydrogen to oil was 1500.

The reaction effluent of the first hydrogenation unit is separated and fractionated, and the yield of dry gas is 2%, the yield of liquefied gas is 4%, the yield of hydrogenated light naphtha is 150%, the yield of hydrogenated heavy naphtha is 40%, and the yield of hydrogenated diesel oil is 39%, wherein the basic properties of light heavy naphtha and hydrogenated diesel oil are shown in table 2.

And mixing the hydrogenated heavy naphtha with the coal tar heavy component at the temperature of 70 ℃, wherein the mass ratio of the coal tar heavy component to the hydrogenated heavy naphtha is 5: 1, mixing, fully stirring to obtain a clear liquid and insoluble substances, and filtering to obtain a clear liquid.

Subjecting the obtained clarified liquid to centrifugal separation to obtain fraction I and fraction II.

The fraction II enters a coking tower and is coked for 6 hours at the coking temperature of 580 ℃, and the yield of needle coke is 45%; calcining the needle coke at 1500 ℃ to obtain calcined coke, and graphitizing to obtain the graphite electrode with the thermal expansion coefficient less than 1 x 10 < -6 >/DEG C.

And extracting the fraction I by aromatic hydrocarbon to obtain a BTX product.

TABLE 1 analysis of properties of coal tar whole fractions

Analysis item	Data of
		Density/(g/cm) at 20 DEG C³)	0.9996
Residual carbon value/%	4.58
		Content of phenol/%)	16.92
Sulfur content/%)	0.39
		Nitrogen content/%)	0.74
Saturated hydrocarbon/%)	23
		Aromatic hydrocarbon/%)	51
Colloid + asphaltene/%)	26

TABLE 2 hydrogenated light and heavy naphtha and Diesel Properties

Claims

1. A method for producing needle coke and BTX from coal tar whole fraction, the method comprising:

(4) separating the clarified liquid obtained in the step (3) to obtain a fraction I and a fraction II, wherein the separation process is a physical separation method;

(6) and (4) extracting the fraction I which is obtained in the step (4) and is a coal tar light component rich in BTX by aromatic hydrocarbon to obtain a BTX product.

2. The method of claim 1, wherein the pretreated coal tar whole fraction feedstock has a metal content of less than 50 μ g/g, a water content of less than 300 μ g/g, and an ash content of less than 0.01%.

3. The method of claim 1, wherein the cut points of the coal tar light component and the coal tar heavy component are 360 ℃ to 390 ℃.

4. The process of claim 1, wherein the hydrogenation unit is a fixed bed hydrocracking unit or a slurry bed hydrocracking unit or an ebullated bed hydrocracking unit.

5. The process of claim 4, wherein the hydrogenation unit is a fixed bed hydrocracking unit.

6. The process of claim 1 or 4, wherein the reaction conditions of the hydrogenation unit comprise: the reaction pressure is 6-30 MPa, the reaction temperature is 320-490 ℃, and the liquid hourly space velocity is 0.1-5.0 h^-1The volume ratio of hydrogen to oil is 200-2000.

7. The process of claim 4, wherein the reaction conditions of the fixed bed hydrocracking unit comprise: the reaction pressure is 10-13 MPa, the reaction temperature is 350-410 ℃, and the liquid hourly space velocity is 0.5-2.0 h^-1The volume ratio of hydrogen to oil is 800-1500.

8. The method of claim 4, wherein the fixed bed hydrocracking unit is filled with a hydrofinishing catalyst and a hydrocracking catalyst, and the filling ratio of the hydrofinishing catalyst to the hydrocracking catalyst is 2: 8-8: 2.

9. the method according to claim 8, wherein the hydrorefining catalyst comprises a carrier selected from at least one of alumina, alumina-silica and titania, and an active metal element supported on the carrier selected from at least one of nickel, cobalt, molybdenum and tungsten.

10. The process according to claim 9, wherein the content of nickel and/or cobalt in terms of oxide in the hydrorefining catalyst is 1 to 30% by weight, and the content of molybdenum and/or tungsten in terms of oxide is 5 to 35% by weight, based on the total weight of the hydrorefining catalyst.

11. The method of claim 8, wherein the hydrocracking catalyst comprises a carrier and an active metal element supported on the carrier, the carrier comprises a molecular sieve and at least one selected from the group consisting of alumina, alumina-silica and titania, and the active metal element is at least one selected from the group consisting of nickel, cobalt, molybdenum and tungsten; the bulk density of the hydrocracking catalyst is 0.4-1.3 g/cm³The average particle diameter of the hydrocracking catalyst is 0.08-1.2 mm, and the specific surface area is 100-300 m²/g。

12. The method of claim 11, wherein the hydrocracking catalyst contains 10 to 60 wt% of the molecular sieve, 1 to 30 wt% of nickel and/or cobalt in terms of oxide, and 5 to 40 wt% of molybdenum and/or tungsten in terms of oxide, based on the total weight of the hydrocracking catalyst.

13. The method according to claim 1, wherein the reaction effluent of the hydrogenation unit is separated and fractionated to obtain hydrogenated light naphtha, hydrogenated heavy naphtha and hydrogenated diesel oil, the cut point between the hydrogenated light naphtha and the hydrogenated heavy naphtha is 65-80 ℃, and the cut point between the hydrogenated heavy naphtha and the hydrogenated diesel oil is 175-190 ℃; wherein the yield of the hydrogenated light naphtha is 10-20%, the yield of the hydrogenated heavy naphtha is 15-70%, and the yield of the hydrogenated diesel oil is 5-60%.

14. The method according to claim 1, wherein the mass ratio of the coal tar heavy component to the hydrogenated heavy naphtha in the step (3) is 0.1-10.

15. The method according to claim 1, wherein the mass ratio of the coal tar heavy component to the hydrogenated heavy naphtha in the step (3) is 2 to 5.

16. The method according to claim 1, wherein the temperature of the heavy coal tar fraction mixed with the hydrogenated heavy naphtha in step (3) is 40 ℃ to 120 ℃.

17. The method of claim 16, wherein the temperature of the heavy coal tar fraction mixed with the hydrogenated heavy naphtha in step (3) is 60 ℃ to 90 ℃.

18. The method of claim 1, wherein the separation process of step (4) is a centrifugal separation process.

19. The method of claim 1, wherein the coal tar whole cut feedstock is a medium and low temperature coal tar whole cut.