A method for coal fractional catalytic direct liquefaction

Abstract

The application discloses a coal grading catalytic direct liquefaction method, which comprises the following steps: (1) feeding oil coal slurry into a first reactor after preheating to carry out a hydroliquefaction reaction; (2) carrying out gas-liquid separation on the material reacted in the first reactor through a gas-liquid separator, and feeding the liquid-solid material obtained through the separation into a hydrocyclone separator to carry out multi-stage separation, wherein the low solid content material separated in the first stage is fed into a second reactor to carry out a deep hydroliquefaction reaction; the high solid content material separated in the second stage is recycled back to the first reactor; and the remaining solid residue separated in the third stage is discharged from the system; and (3) carrying out product separation on the reaction product from the second reactor to obtain a target product coal direct liquefaction oil. The application can significantly improve the synergistic conversion of the maceral in coal, has high coal liquefaction conversion rate and oil yield, and has wide coal adaptability, and is not only suitable for high-oxygen low-rank coal, but also suitable for bituminous coal, sub-bituminous coal and the like with high inert component.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coal direct liquefaction, and in particular to a method for coal direct liquefaction by grading and catalysis. BACKGROUND

[0002] Coal direct liquefaction technology mainly refers to the process of breaking down the macromolecular structure of coal under high temperature and high pressure, and further converting it into small molecule liquid fuel through hydrogenation reaction. The chemical composition of coal is very complex, mainly composed of macromolecules with several condensed aromatic ring basic structural units with side chains and functional groups. Due to the complexity of its structure, the temperature range of coal thermal decomposition is quite wide and shows a certain sequence. In addition, it is generally believed that the vitrinite component in the maceral of coal is the component that is easy to be liquefied and converted, while the liquefaction and conversion of the inertinite component often requires more severe conditions or longer reaction time.

[0003] Coal direct liquefaction processes are mainly divided into single-stage liquefaction processes such as IGOR process in Germany, NEDOL process in Japan, and multi-stage liquefaction processes such as CTSL process in the United States, HTI process, and China Shenhua process. In the above processes, the oil coal slurry is preheated and then enters the liquefaction reactor, and then the material enters the separator for separation to obtain coal liquefied oil. Among them, China Shenhua process (CN1587351A) adopts a forced internal circulation suspended bed reactor to realize the cooperative conversion of maceral in the reactor, that is, to prolong the reaction time of inertinite component and to quickly separate the liquefied product, but the internal components of the reactor used in this process are complex and are prone to mineral deposition. In the above main coal direct liquefaction processes, bituminous coal and sub-bituminous coal are mostly used as raw materials, while lignite is less used. This is because lignite has a low degree of coalification, a high oxygen content and a high water content, which increases the drying cost and hydrogen consumption in the liquefaction process, and reduces the economic efficiency of the process. However, lignite has abundant reserves, high reactivity and high hydrogen-carbon ratio, which determines that it is a suitable coal type for coal direct liquefaction process.

[0004] Chinese patent CN108641741A discloses a coal direct liquefaction process, which uses oil coal slurry to pass through three-stage series reactors respectively added with alkali catalyst, iron catalyst and noble metal catalyst to obtain coal liquefied oil. However, this method has a long process flow, and the one-pass material cannot effectively realize the efficient conversion of different maceral components, that is, the easily converted components and the difficultly converted components cannot be separated in time, resulting in easy secondary cracking of small molecule products.

[0005] Therefore, it is necessary to develop a new coal direct liquefaction process to solve the problems existing in the prior art, such as low adaptability of coal type, which is not only suitable for high-oxygen and high-water low-rank coal, but also insensitive to the direct liquefaction performance difference of different maceral components in coal. Starting from the chemical molecular structure of coal, the liquefaction conversion rate and oil yield are further improved. SUMMARY

[0006] The present application aims to provide a coal graded catalytic direct liquefaction method to improve the adaptability to different coal types, which is suitable not only for high-oxygen low-rank coal, but also for bituminous coal, sub-bituminous coal and the like with high inert component.

[0007] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0008] A coal graded catalytic direct liquefaction method, the method comprising the following steps:

[0009] (1) Preheating the oil coal slurry and then feeding it into a first reactor for hydroliquefaction reaction;

[0010] (2) Carrying out gas-liquid separation on the reacted material in the first reactor through a gas-liquid separator, and feeding the separated liquid-solid material into a hydrocyclone separator for multi-stage separation, wherein the low solid content material separated in the first stage is fed into a second reactor for deep hydrocracking reaction; the high solid content material separated in the second stage is recycled back to the first reactor; and the remaining solid residue separated in the third stage is discharged from the system;

[0011] (3) Carrying out product separation on the reaction product from the second reactor to obtain the target product coal direct liquefaction oil.

[0012] In step (1) of the present application, the oil coal slurry is preheated and then fed into a first reactor for hydroliquefaction reaction; wherein the coal used to prepare the oil coal slurry can be bituminous coal, sub-bituminous coal and the like with high inert component; in a preferred embodiment, the operating temperature of the first reactor is 380-440℃, such as 390, 400, 410, 420 or 430℃, and the operating pressure is 6-20MPa, such as 8, 10, 12, 14, 16, 18 or 20MPa; the reaction atmosphere is a synthetic gas atmosphere or a hydrogen-rich atmosphere, and the reaction residence time is 20-100min, such as 40, 60 or 80min.

[0013] In a preferred embodiment, the hydrogenation catalyst used in the first reactor is a first composite catalyst comprising an iron catalyst, an auxiliary sulfur and an alkali catalyst, so as to promote the pyrolytic depolymerization of the main molecular structure of coal, and reduce the negative effects of the increased hydrogen consumption and the reduced hydrogen partial pressure caused by the water generated in the direct liquefaction of high-oxygen coal. In the present application, the iron catalyst can be one or more of iron-containing minerals, iron oxides, iron sulfides and iron hydroxides; in one embodiment, the iron catalyst can be γ-FeOOH. In the present application, the alkali catalyst can be one or more of alkali metal-containing minerals, alkali metal sodium or potassium hydroxides, carbonates, aluminates or silicates; in one embodiment, the alkali catalyst can be Na2CO3.

[0014] In preferred embodiments, the first reactor, the amount of iron catalyst added is 0.5-5wt%, such as 1, 2, 3 or 4wt%, the amount of base catalyst added is 0.5-5wt%, such as 1, 2, 3 or 4wt%, and the ratio of the amount of iron catalyst added to the amount of base catalyst added is 2:1-1:2, such as 1.5:1, 1:1 or 1:1.5, wherein the amount of sulfur added in the first composite catalyst is such that the atomic ratio of S to Fe in the first composite catalyst is 1-2:1, such as 1.2:1, 1.5:1 or 1.8:1.

[0015] In step (2) of the present application, the material after reaction in the first reactor is first subjected to gas-liquid separation in a gas-liquid separator to separate water, unreacted gas and light components, and the remaining liquid-solid material is sent to a hydrocyclone separator for multi-stage separation. Multi-stage separation using a hydrocyclone separator is well known in the art, for example, two hydrocyclone separators in series are used for multi-stage separation, which will not be described here.

[0016] In the present application, when the liquid-solid material from the gas-liquid separator is subjected to multi-stage separation, the low solid content material separated in the first stage is sent to the second reactor for deep hydrogenation reaction, and those skilled in the art understand that the temperature and pressure can be adjusted as needed before being sent to the second reactor; the high solid content material separated in the second stage is recycled back to the first reactor to achieve synergistic conversion of micro-components; the remaining solid residue separated in the third stage is discharged from the system. Through multi-stage separation, not only the solid residue that cannot be converted is removed from the system, but also the low solid content material and the high solid content material can be further processed, taking into account product conversion and processing efficiency.

[0017] In preferred embodiments, the solid content of the low solid content material is not more than 15wt%, such as 5wt%, 8wt% or 12wt%, and the solid content of the solid residue is not less than 90wt%, such as 94wt%, 96wt% or 98wt%.

[0018] In step (2) of the present application, the low solid content material separated in the first stage is sent to the second reactor for deep hydrogenation reaction to further open the ring and break the chain, to obtain coal direct liquefaction oil, which is well known in the art. In some embodiments, the operating temperature of the second reactor is 430-470°C, such as 440, 450 or 460°C, and the operating pressure is 10-22MPa, such as 12, 15, 18 or 20MPa; the reaction atmosphere is a hydrogen-rich atmosphere, and the reaction residence time is 20-100min, such as 40, 60 or 80min.

[0019] In some embodiments, the hydrogenation catalyst used in the second reactor is a second composite catalyst comprising an iron catalyst, a promoter sulfur, and a nickel / molybdenum / cobalt catalyst, wherein the nickel / molybdenum / cobalt catalyst is commonly a supported catalyst supporting one or more of the active metal components molybdenum, nickel and cobalt oxides, such as a supported catalyst supporting molybdenum and nickel oxides on an alumina support, wherein the nickel oxide accounts for 4-9 wt% of the supported catalyst, such as 5 wt%, 6 wt% or 8 wt%, and the molybdenum oxide accounts for 5-23 wt% of the catalyst, such as 8 wt%, 10 wt%, 12 wt%, 15 wt% or 20 wt%, for example, one or more of the commercial RNC-2 catalyst (Research Institute of Petroleum Processing), HRK658 (Axens) or FFT-1 catalyst (Fushun Research Institute of Petroleum and Petrochemicals); which are well known in the art and will not be described here.

[0020] In other embodiments, the nickel / molybdenum / cobalt catalyst can also be one or more of a nickel-containing ore, a molybdenum-containing ore, a cobalt-containing ore, a nickel, molybdenum, cobalt oxide or a nickel, molybdenum, cobalt sulfide, which are well known in the art and will not be described here.

[0021] In preferred embodiments, in the second reactor, the iron catalyst is added in an amount of 0.5-5 wt% of the dry ash-free raw coal used to prepare the oil coal slurry, such as 1, 2, 3 or 4 wt%, and the nickel / molybdenum / cobalt catalyst is added in an amount of 0.1-3 wt% of the dry ash-free raw coal, such as 0.5, 1, 2 or 2.5 wt%, and the ratio of the amount of the iron catalyst to the amount of the nickel / molybdenum / cobalt catalyst is 5:1-2:1, such as 3:1 or 4:1; wherein the promoter sulfur is added in a S / Fe atomic ratio of 1-2:1, i.e. the atomic ratio of S in the promoter sulfur to Fe in the iron catalyst is 1-2:1, such as 1.2:1, 1.5:1 or 1.8:1.

[0022] In preferred embodiments, the temperature in the second reactor is 30-50°C higher than that in the first reactor, such as 40°C, and the pressure is 1.5-2.5 MPa higher than that in the first reactor, such as 2 MPa, to better perform deep hydroprocessing.

[0023] In the present application, the synthesis gas atmosphere is a mixed gas containing CO and H2, wherein the CO concentration is not less than 10 vol%, such as 10-40 vol%, 20 vol% or 30 vol%, and the H2 concentration is not less than 50 vol%, such as 60-90 vol%, 70 vol% or 80 vol%.

[0024] In the present application, the hydrogen-rich atmosphere is pure hydrogen gas or a hydrogen-rich gas with a H2 volume concentration of not less than 70 vol%, such as 80 vol% or 90 vol%.

[0025] In a preferred embodiment, the low solid content material separated by the hydrocyclone has a solid content of no more than 10wt%, and the solid residue has a solid content of no less than 95wt%.

[0026] In step (3) of the present application, the reaction product is subjected to product separation to obtain the target product, coal direct liquefaction oil, wherein the heavy liquid product and part of the medium and light products are processed for oil coal slurry preparation, which are well known in the art and will not be described here.

[0027] In the present application, the raw coal used for preparing the oil coal slurry can be lignite, sub-bituminous coal and / or bituminous coal. Preferably, the oil coal slurry can be prepared using high-inertite coal, wherein the inertite in the raw coal is no more than 60wt%, such as 15-50wt%, 20wt%, 30wt% or 40wt%.

[0028] In the present application, the oil coal slurry can be prepared using dry coal, partially dry coal and non-dry coal.

[0029] Compared with the prior art, the present application has the following advantages:

[0030] The present application provides a coal grading catalytic direct liquefaction process, which first promotes the decomposition of low-energy oxygen-containing structures in coal in a first reactor by using an iron base catalyst + synthesis gas or a hydrogen-rich system, which is beneficial to the depolymerization of coal macromolecular structure and avoids the negative effects of increased hydrogen consumption and reduced local hydrogen partial pressure caused by a large amount of water produced by high-oxygen coal liquefaction; secondly, a gas-liquid separator + hydrocyclone is used to quickly separate light low-boiling-point oil and liquefaction water, and then the high-solid-content reaction material after reaction is recycled back to the first reactor for further deep reaction, thereby prolonging the reaction time of inertite and other difficult-to-react components; at the same time, the low-solid-content asphaltene macromolecules are sent to a second reactor, and high-efficiency hydrogenation of the low-solid-content asphaltene macromolecules is carried out in the second reactor by using a high-hydrogenation-activity iron-nickel / molybdenum / cobalt catalyst + hydrogen atmosphere, thereby promoting the conversion of the low-solid-content asphaltene macromolecules to liquefied oil; through the above method, efficient conversion of different macromolecular components is realized. By using the present method, the secondary decomposition of small molecule products can be reduced, and the deep hydrogenation conversion of macromolecular inertite and other difficult-to-react components can be strengthened, thereby improving the overall oil yield of coal liquefaction. In addition, the present method has strong adaptability to coal types, can effectively reduce the adverse effects of water produced by high-oxygen low-rank coal liquefaction on the reaction system, and can improve the liquefaction performance of coal samples with high inertite components.

[0031] The present application realizes efficient and synergistic conversion of different macerals in coal while retaining the promotion of efficient liquefaction performance of low-rank coal, on the one hand, by prolonging the reaction residence time of high-solid-content material, improving the reaction depth of inert macerals, and promoting the depolymerization and conversion of macromolecular structure of the inert macerals by iron and alkali catalytic system, on the other hand, by rapidly separating the converted small-molecule products and low-solid-content asphaltene macromolecules, preventing the increase of gas yield caused by excessive reaction of small-molecule products, and then by efficient hydroliquefaction of low-solid-content asphaltene macromolecules by high hydrogenation activity catalytic system, promoting the conversion to liquefied oil. The present technical solution has high adaptability to coal types, is suitable for high-oxygen low-rank coal, can realize efficient and synergistic conversion of macerals, and is also beneficial to the hydroliquefaction conversion of high-inert-maceral coal. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 A flowchart for coal liquefaction by the method of the present application;

[0033] Reference signs:

[0034] 1 - preheater; 2 - first reactor; 3 - gas-liquid separator; 4 - hydrocyclone separator; 5 - second reactor; 6 - separation unit. DETAILED DESCRIPTION

[0035] In order to make the personnel in the technical field better understand the present application scheme, the technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the personnel in the field without creative labor should belong to the protection scope of the present application.

[0036] As shown in Figure 1 The method for coal two-stage catalytic direct liquefaction provided by the present application is a coal two-stage catalytic hydroliquefaction method, that is, the oil coal slurry is preheated by a preheater 1 and then sent into a first reactor 2 for hydroliquefaction reaction; then, the material after reaction in the first reactor is subjected to gas-liquid separation by a gas-liquid separator 3, so that the water and light oil in the material are separated from the reaction gas and discharged; the liquid-solid material is subjected to multi-stage separation by a hydrocyclone separator 4, the low-solid-content material is separated out in the first stage and then sent into a second reactor 5 for deep hydrocracking; the high-solid-content material is separated out in the second stage and then returned to the first reactor for synergistic conversion of macerals; the remaining solid residue is separated out in the third stage and then discharged from the system; finally, the reaction product from the second reactor is subjected to product separation in a separation unit 6, and the target product coal direct liquefaction oil is obtained.

[0037] The method of the present application realizes efficient and synergistic conversion of different macerals in coal while retaining the performance of promoting the liquefaction of high-oxygen-containing low-rank coal, on the one hand, by prolonging the reaction residence time of high-solid-content inert macerals, improving the reaction depth of the inert macerals, and promoting the depolymerization and conversion of the macromolecular structure of the inert macerals by an iron-alkali catalytic system, and on the other hand, by rapidly separating the converted small-molecule products and low-solid-content asphaltene macromolecules, preventing excessive reaction of the small-molecule products to increase the gas yield, and then by efficiently hydrogenating and liquefying the low-solid-content asphaltene macromolecules by a high-hydrogenation-activity catalytic system to promote the conversion to liquefied oil.

[0038] The first reactor of the method of the present application uses a synthesis gas or hydrogen-rich gas and an iron-alkali catalytic system to promote the pyrolysis and depolymerization of the macromolecular structure of coal, reduce the negative effects of the increase in hydrogen consumption and the decrease in hydrogen partial pressure caused by the generation of water during direct liquefaction of high-oxygen-containing coal, and return the high-solid-content material at the outlet of the first reactor to the first reactor through a high-temperature hydrocyclone separator, and the low-solid-content material enters the second reactor for further efficient hydrogenation and liquefaction, thereby increasing the residence time of the high-solid-content material that is difficult to convert and promoting its conversion; the low-solid-content material enters the second reactor for further efficient hydrogenation and liquefaction under a high-hydrogenation-activity iron-nickel / molybdenum / cobalt catalytic system, promotes the hydrogenation and conversion of the low-solid-content asphaltene macromolecules to small-molecule oil, and realizes efficient and synergistic conversion of macerals.

[0039] The following further illustrates specific examples / counter-examples:

[0040] Table 1 Basic properties of coal samples

[0041]

[0042] The following examples take young lignite (Xilin coal), sub-bituminous coal (Shendong coal) and young bituminous coal (Hongliulin coal) as examples, and the basic properties thereof are shown in Table 1.

[0043] The nickel / molybdenum / cobalt-containing catalyst used in the following examples / counter-examples is a commercial HRK-658 catalyst (Ni-Mo / Al2O3, Axens Company)

[0044] Example 1

[0045] The oil slurry prepared from Xilinhaote coal is preheated and then fed into the first reactor. The operating temperature of the first reactor is 380°C, and the operating pressure is 6 MPa. The material is fully contacted with the first composite catalyst (the addition amount of the iron catalyst (γ-FeOOH) is 0.5 wt% based on the dry ash-free raw coal, and the addition amount of the alkali catalyst (Na2CO3) is 0.5 wt%, wherein the addition amount of the sulfur additive is S / Fe = 1.2:1) under a synthesis gas atmosphere (CO:H2 = 1:9) for 20 min. The reacted material is separated by a gas-liquid separator, and the moisture and light oil are separated from the reaction gas. The liquid-solid material is fed into a hydrocyclone separator, and the high solid content material is returned to the first reactor. The low solid content material (the solid content is controlled to be not more than 10 wt%) is fed into the second reactor, and the remaining solid residue (the solid content is controlled to be not less than 90 wt%) is discharged.

[0046] The operating temperature of the second reactor is 430°C, and the operating pressure is 10 MPa. The material is fully contacted with the second composite catalyst (the addition amount of the iron catalyst (γ-FeOOH) is 0.5 wt% based on the dry ash-free raw coal, and the addition amount of the nickel / molybdenum / cobalt catalyst (Ni-Mo / Al2O3) is 0.1 wt%, wherein the addition amount of the sulfur additive is S / Fe = 1.2:1) under a pure hydrogen atmosphere for 20 min. The reacted material is separated to obtain the target product, i.e., coal direct liquefaction oil. The heavy liquid product and part of the medium and light products are processed to be used for oil slurry preparation.

[0047] The product yield (based on the dry ash-free coal mass) is detected to be: oil yield 53.3%, water yield 12.2%, gas yield 13.5%, asphaltene yield 10.4%, and residue yield 10.6% (conversion rate 89.4%).

[0048] Example 2

[0049] The oil slurry prepared from Xilinhaote coal is preheated and then fed into the first reactor. The operating temperature of the first reactor is 440°C, and the operating pressure is 20 MPa. The material is fully contacted with the first composite catalyst (the addition amount of the iron catalyst (γ-FeOOH) is 5 wt% based on the dry ash-free raw coal, and the addition amount of the alkali catalyst (Na2CO3) is 5 wt%, wherein the addition amount of the sulfur additive is S / Fe = 2:1) under a synthesis gas atmosphere (CO:H2 = 4:6) for 100 min. The reacted material is separated by a gas-liquid separator, and the moisture and light oil are separated from the reaction gas. The liquid-solid material is fed into a hydrocyclone separator, and the high solid content material is returned to the first reactor. The low solid content material is fed into the second reactor.

[0050] The second reactor is operated at a temperature of 470°C and a pressure of 22 MPa in a pure hydrogen atmosphere, and the material is fully contacted with the second composite catalyst (5 wt% of iron catalyst (γ-FeOOH) and 3 wt% of nickel / molybdenum / cobalt catalyst (Ni-Mo / Al2O3) are added based on the mass of the dry and ash-free raw coal, and the additive sulfur is added at a ratio of S / Fe=1.5:1), and the residence time is 100 min. The reacted material is subjected to product separation to obtain the target product, coal direct liquefaction oil, and the heavy liquid product and part of the medium and light products are processed to be used for oil coal slurry preparation.

[0051] The product yield (based on the mass of the dry and ash-free coal) is detected as follows: oil yield 54.6%, water yield 11.5%, gas yield 14.4%, asphaltene yield 8.2%, and residue yield 11.3% (conversion rate 88.7%).

[0052] Example 3

[0053] The oil coal slurry prepared from Xilinhaote coal is preheated and then introduced into the first reactor, which is operated at a temperature of 430°C and a pressure of 17 MPa in a synthetic gas atmosphere (CO:H2=2:8), and the material is fully contacted with the first composite catalyst (3 wt% of iron catalyst (γ-FeOOH) and 3 wt% of alkali catalyst (Na2CO3) are added based on the mass of the dry and ash-free raw coal, and the additive sulfur is added at a ratio of S / Fe=1.5:1), and the residence time is 60 min. The reacted material is subjected to gas-liquid separation, and the water and light oil are separated from the reaction gas, and the liquid and solid material is introduced into the hydrocyclone separator, and the high solid content material is returned to the first reactor, and the low solid content material is introduced into the second reactor.

[0054] The second reactor is operated at a temperature of 460°C and a pressure of 19 MPa in a pure hydrogen atmosphere or a hydrogen-rich atmosphere, and the material is fully contacted with the second composite catalyst (3 wt% of iron catalyst (γ-FeOOH) and 1 wt% of nickel / molybdenum / cobalt catalyst (Ni-Mo / Al2O3) are added based on the mass of the dry and ash-free raw coal, and the additive sulfur is added at a ratio of S / Fe=1.5:1), and the residence time is 60 min. The reacted material is subjected to product separation to obtain the target product, coal direct liquefaction oil, and the heavy liquid product and part of the medium and light products are processed to be used for oil coal slurry preparation.

[0055] The product yield (based on the mass of the dry and ash-free coal) is detected as follows: oil yield 55.2%, water yield 12.1%, gas yield 13.3%, asphaltene yield 10.9%, and residue yield 8.5% (conversion rate 91.5%).

[0056] Example 4

[0057] The oil slurry prepared from Shendong coal is preheated and then fed into the first reactor, the operating temperature of the first reactor is 430°C, the operating pressure is 19 MPa, and the material is fully contacted with the first composite catalyst under the atmosphere of synthesis gas (CO:H2=1:9) (based on the mass of the dry and ash-free raw coal, the addition amount of iron catalyst (γ-FeOOH) is 1wt%, the addition amount of alkali catalyst (Na2CO3) is 1wt%, and the addition amount of sulfur additive is S / Fe=1.5:1), the residence time is 80 min; the reacted material is separated by a gas-liquid separator, the moisture and light oil are separated from the reaction gas, the liquid-solid material is fed into a hydrocyclone separator, the high solid-containing material is returned to the first reactor, and the low solid-containing material is fed into the second reactor;

[0058] The operating temperature of the second reactor is 450°C, the operating pressure is 19 MPa, and the material is fully contacted with the second composite catalyst under the atmosphere of pure hydrogen or hydrogen-rich atmosphere (based on the mass of the dry and ash-free raw coal, the addition amount of iron catalyst (γ-FeOOH) is 1wt%, the addition amount of nickel / molybdenum / cobalt-containing catalyst (Ni-Mo / Al2O3) is 1wt%, and the addition amount of sulfur additive is S / Fe=1.5:1), the residence time is 60 min; the reacted material is separated to obtain the target product coal direct liquefaction oil, and the heavy liquid product and part of the medium and light products are processed to be used for oil slurry preparation.

[0059] It is detected that the product yield (based on the mass of the dry and ash-free coal) is as follows: oil yield 52.2%, water yield 11.8%, gas yield 12.4%, asphaltene yield 14.1%, and residue yield 11.5% (conversion rate 90.5%).

[0060] Example 5

[0061] The oil slurry prepared from Hongliulin coal is preheated and then fed into the first reactor, the operating temperature of the first reactor is 430°C, the operating pressure is 10 MPa, and the material is fully contacted with the first composite catalyst under the atmosphere of synthesis gas (CO:H2=2:8) (based on the mass of the dry and ash-free raw coal, the addition amount of iron catalyst (γ-FeOOH) is 1.5wt%, the addition amount of alkali catalyst (Na2CO3) is 1.5wt%, and the addition amount of sulfur additive is S / Fe=1.5:1), the residence time is 60 min; the reacted material is separated by a gas-liquid separator, the moisture and light oil are separated from the reaction gas, the liquid-solid material is fed into a hydrocyclone separator, the high solid-containing material is returned to the first reactor, and the low solid-containing material is fed into the second reactor;

[0062] The second reactor is operated at a temperature of 450°C and a pressure of 15 MPa in a pure hydrogen atmosphere or a hydrogen-rich atmosphere, and the material is fully contacted with a second composite catalyst (3% of iron catalyst (γ-FeOOH) and 1% of nickel / molybdenum / cobalt catalyst (Ni-Mo / Al2O3) are added based on the mass of the dry and ash-free raw coal, and the additive sulfur is added according to S / Fe=1.5:1), and the residence time is 60 min. The reacted material is subjected to product separation to obtain the target product coal direct liquefaction oil, and the heavy liquid product and part of the medium and light products are processed to be used for oil coal slurry preparation.

[0063] It is detected that the product yield (based on the mass of the dry and ash-free coal) is as follows: oil yield 53.3%, water yield 9.6%, gas yield 14.8%, asphaltene yield 12.1%, and residue yield 10.2% (conversion rate 89.8%).

[0064] Comparative Example 1

[0065] The oil coal slurry prepared from Hongliulin coal is preheated and then introduced into the first reactor, which is operated at a temperature of 430°C and a pressure of 10 MPa in a pure hydrogen atmosphere, and the material is fully contacted with an iron catalyst (3% of iron catalyst (γ-Fe2O3) is added, and the additive sulfur is added according to S / F=1.5), and the residence time is 60 min. The reacted material is directly introduced into the second reactor.

[0066] The second reactor is operated at a temperature of 450°C and a pressure of 15 MPa in a pure hydrogen atmosphere, and the material is fully contacted with an iron catalyst (4% of iron catalyst (γ-Fe2O3) is added), and the residence time is 60 min. The reacted material is subjected to product separation to obtain the target product coal direct liquefaction oil, and the heavy liquid product and part of the medium and light products are processed to be used for oil coal slurry preparation.

[0067] It is detected that the product yield (based on the mass of the dry and ash-free coal) is as follows: oil yield 49.4%, water yield 10.3%, gas yield 11.1%, asphaltene yield 15.6%, and residue yield 14.5% (conversion rate 86.5%).

[0068] Comparative Example 1-1

[0069] The difference from Comparative Example 1 is that the reaction atmosphere and catalyst in the first reactor are replaced by the synthesis gas atmosphere (CO:H2=2:8) and the first composite catalyst of Example 5, respectively, and the rest is the same as Comparative Example 1.

[0070] It is detected that the product yield (based on the mass of the dry and ash-free coal) is as follows: oil yield 50.1%, water yield 9.2%, gas yield 11.8%, asphaltene yield 16.1%, and residue yield 12.8% (conversion rate 87.2%).

[0071] Comparative Example 2

[0072] The oil coal slurry prepared from Shendong coal was preheated and then fed into the first reactor. The operating temperature of the first reactor was 430°C, the operating pressure was 19 MPa, and the material was fully contacted with the iron catalyst (γ-FeOOH) under a pure hydrogen atmosphere. The addition amount of the iron catalyst was 2%, the addition amount of the additive sulfur was calculated according to S / F = 1.5, and the residence time was 80 min. The reacted material was directly fed into the second reactor. The operating temperature of the second reactor was 450°C, the operating pressure was 19 MPa, and the material was fully contacted with the iron catalyst (γ-FeOOH) under a pure hydrogen atmosphere. The addition amount of the iron catalyst was 2%, and the residence time was 80 min. The reacted material was subjected to product separation to obtain the target product coal direct liquefaction oil. The heavy liquid product and part of the medium and light products were processed and used for oil coal slurry preparation.

[0073] It was detected that the product yield (based on the mass of dry ash-free coal) was as follows: oil yield 46.1%, water yield 9.8%, gas yield 11.3%, asphaltene yield 18.3%, and residue yield 14.5% (conversion rate 85.5%).

[0074] Comparative Example 3

[0075] Compared with Example 1, the difference was that the reaction system was the coal direct liquefaction system shown in CN1869159A. In the system, part of the products in the high-temperature separator were recycled to the first reactor, and the recycling ratio was 10:1. Figure 1

[0076] It was detected that the product yield (based on the mass of dry ash-free coal) was as follows: oil yield 49.1%, water yield 11.5%, gas yield 10.8%, asphaltene yield 15.6%, and residue yield 13.2% (conversion rate 86.8%). Compared with Example 1, the asphaltene yield was increased, and the conversion rate and the oil yield were obviously decreased.

[0077] As can be seen from the comparison of the above examples / comparative examples, the use of the multi-stage separation system after the first reactor of the coal direct liquefaction in the present application can effectively improve the coal liquefaction conversion rate and the oil yield, especially for the high-inert group Shendong coal. The multi-stage separation system can extend the reaction residence time of the high-solid-content inert group, improve the reaction depth of the inert group, promote the depolymerization and conversion of the macromolecular structure through the iron-alkali catalyst system, on the other hand, quickly separate the converted small molecule products and low-solid-content asphaltene macromolecules to prevent the over-reaction of the small molecule products, and then promote the liquefaction of the low-solid-content asphaltene macromolecules through the high hydrogenation activity catalyst system to promote the conversion to liquefied oil and improve the overall oil yield and conversion rate of the coal direct liquefaction.​

Claims

1. A method of coal fractionated catalytic direct liquefaction, characterized by, The method comprises the following steps: (1) the oil coal slurry is preheated and then sent into a first reactor for hydroliquefaction reaction; wherein the inert content of the raw coal used for preparing the oil coal slurry is 20wt%-50wt%; (2) the material reacted in the first reactor is subjected to gas-liquid separation through a gas-liquid separator, and the liquid-solid material obtained by the separation is sent into a hydrocyclone separator for multi-stage separation; wherein the low solid content material separated in the first stage is sent into a second reactor for deep hydroliquefaction reaction; the high solid content material separated in the second stage is recycled back to the first reactor to prolong the residence time of the inert; and the remaining solid residue separated in the third stage is discharged from the system; wherein the solid content of the low solid content material separated by the hydrocyclone separator is not more than 15wt%, and the solid content of the solid residue is not less than 90wt%; (3) the reaction product from the second reactor is subjected to product separation to obtain a target product, i.e. coal direct liquefaction oil.

2. The method of claim 1, wherein, The operating temperature of the first reactor is 380-440℃, and the operating pressure is 6-20MPa; the reaction atmosphere is a synthetic gas atmosphere or a hydrogen-rich atmosphere, the reaction catalyst is a first composite catalyst of an iron catalyst, an auxiliary sulfur and an alkali catalyst, and the reaction residence time is 20-100min.

3. The method of claim 2, wherein, The operating temperature of the second reactor is 430-470℃, and the operating pressure is 10-22MPa; the reaction atmosphere is a hydrogen-rich atmosphere, the reaction catalyst is a second composite catalyst of an iron catalyst, an auxiliary sulfur and a nickel / molybdenum / cobalt catalyst, and the reaction residence time is 20-100min; wherein the nickel / molybdenum / cobalt catalyst is a supported catalyst loaded with one or more of oxides of active metal components molybdenum, nickel and cobalt.

4. The method of claim 3, wherein, The temperature in the second reactor is 30-50℃ higher than that in the first reactor, and the pressure is 1.5-2.5MPa higher than that in the first reactor.

5. The method of claim 2, wherein, In the first reactor, the addition amount of the iron catalyst is 0.5-5wt% based on the dry ash-free raw coal used for preparing the oil coal slurry, the addition amount of the alkali catalyst is 0.5-5wt%, and the mass ratio of the addition amount of the iron catalyst to the addition amount of the alkali catalyst is 2:1-1:2; wherein the auxiliary sulfur in the first composite catalyst is added in an S / Fe atomic ratio of 1-2:

1.

6. The method of claim 3, wherein, In the second reactor, the addition amount of the iron catalyst is 0.5-5wt% based on the dry ash-free raw coal used for preparing the oil coal slurry, the addition amount of the nickel / molybdenum / cobalt catalyst is 0.1-3wt%, and the mass ratio of the addition amount of the iron catalyst to the addition amount of the nickel / molybdenum / cobalt catalyst is 5:1-2:1; wherein the auxiliary sulfur in the second composite catalyst is added in an S / Fe atomic ratio of 1-2:1; wherein the nickel / molybdenum / cobalt catalyst is a supported catalyst loaded with one or more of oxides of active metal components molybdenum, nickel and cobalt.

7. The method of claim 6, wherein, The synthetic gas atmosphere is a mixed gas containing CO and H2, wherein the volume concentration of CO is not less than 10%, and the volume concentration of H2 is not less than 50%; In the first reactor and the second reactor, the hydrogen-rich atmosphere is a hydrogen-rich gas with a volume concentration of H2 not less than 70%.

8. The method of claim 6, wherein, The synthesis gas atmosphere is a mixed gas containing CO and H2, wherein the volume concentration of CO is not less than 10%, and the volume concentration of H2 is not less than 50%. In the first reactor and the second reactor, the hydrogen-rich atmosphere is pure hydrogen gas.

9. The method according to claim 7 or 8, characterized in that, The alkali catalyst comprises one or more of alkali-containing minerals, hydroxides, carbonates, aluminate or silicate of alkali metals sodium or potassium; In the first reactor and the second reactor, the iron catalyst comprises one or more of iron-containing minerals, oxides, sulfides and hydroxides of iron; The nickel / molybdenum / cobalt catalyst is a supported catalyst loaded with oxides of molybdenum and nickel.

10. The method of claim 9, wherein, The alkali catalyst is sodium carbonate; In the first reactor and the second reactor, the iron catalyst is γ-FeOOH.

11. The method according to claim 9 or 10, characterized in that, The raw coal for preparing oil coal slurry is lignite, sub-bituminous coal and / or bituminous coal.

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