Preparation method of sodium ferric disulfide catalyst and application of sodium ferric disulfide catalyst in direct coal liquefaction

Abstract

The application provides a preparation method of a sodium ferrous disulfide catalyst and application of the sodium ferrous disulfide catalyst in direct coal liquefaction, and relates to the technical field of coal liquefaction.The preparation method of the sodium ferrous disulfide catalyst comprises the following steps: mixing a ferric salt solution and a Na2S solution or a NaHS solution, performing a precipitation reaction, and obtaining a precipitation reaction system; and aging the precipitation reaction system, and performing solid-liquid separation to obtain the sodium ferrous disulfide catalyst.The preparation method of the NaFeS2 catalyst is simple in process, mild in preparation condition, does not need heating and pressurization, has a wide source of raw materials, is low in cost, and is easy to be industrialized.The obtained sodium ferrous disulfide has high catalytic activity as a catalyst for direct coal liquefaction, and the oil yield and conversion rate of direct coal liquefaction are higher than those of a catalyst used in the industry at present.

Description

Technical Field

[0001] This invention belongs to the field of direct coal liquefaction technology, specifically relating to a method for preparing sodium iron disulfide catalyst and its application in direct coal liquefaction. Background Technology

[0002] Direct coal liquefaction (DCL) is the process of converting coal into liquid fuels and chemical feedstocks through hydrogenation under high temperature, high pressure, and catalytic conditions. Developing DCL technology can improve coal utilization efficiency and reduce the environmental impact of coal use, making it a clean and efficient way to utilize coal. Catalysts play a crucial role in DCL, activating reactants, accelerating the hydrogenation rate, and promoting hydrogen transfer between the hydrogen source and coal. Developing highly efficient catalysts is an important way to improve the efficiency and economics of DCL.

[0003] Currently, coal direct hydrogenation liquefaction catalysts can be mainly divided into three categories: The first category is nickel and molybdenum-based catalysts, such as Co, Mo, Ni, and W. These catalysts are mostly used for the catalytic hydrogenation of heavy oil and have high catalytic hydrogenation activity, but they are expensive. The second category is solid acid catalysts, such as metal chlorides like SnCl2 and ZnCl2. They have good hydrogenation activity, but they are prone to causing equipment corrosion. The third category is iron-based catalysts. Although their activity is not as good as the above two categories, they are widely available, inexpensive, and do not require recycling.

[0004] Traditional iron-based catalysts, while possessing cracking activity, exhibit weak hydrogenation activity, making it difficult to break the bridging bonds (such as short bridging chains between condensed aromatic rings) in intermediate products asphaltene and preasphemes, thus hindering further improvements in the yield of direct coal liquefaction oil. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing sodium iron disulfide catalyst and its application in direct coal liquefaction. The method for preparing the NaFeS2 catalyst provided by this invention is simple and the conditions are mild. The resulting NaFeS2, as a catalyst for direct coal liquefaction, has a high yield of direct coal liquefaction oil.

[0006] To achieve the objectives of this invention, the following technical solutions are provided:

[0007] A method for preparing a sodium iron disulfide catalyst includes the following steps:

[0008] A ferric salt solution is mixed with a Na₂S solution or a NaHS solution to carry out a precipitation reaction, resulting in a precipitation reaction system.

[0009] The precipitation reaction system was aged and then separated into solid and liquid phases to obtain the sodium iron disulfide catalyst.

[0010] Preferably, the concentration of the ferric salt solution is 0.1–2.4 mol / L.

[0011] Preferably, the concentrations of the Na₂S solution and the NaHS solution are independently 0.15–1.2 mol / L;

[0012] The molar ratio of S in the Na2S solution or NaHS solution to Fe in the ferric salt solution is ≥2.

[0013] Preferably, the precipitation reaction is carried out under stirring conditions; the temperature of the precipitation reaction is 10-90°C, and the time is 1-3 hours.

[0014] Preferably, the aging temperature is 10–40°C and the time is 2–24 hours.

[0015] Preferably, the solid-liquid separation process further includes grinding the sodium iron disulfide catalyst to a particle size of <125μm.

[0016] Preferably, the sodium iron disulfide catalyst further includes a coal support, which is a coal support and sodium iron disulfide supported on the coal support; the mass ratio of Fe to coal in the sodium iron disulfide catalyst is 1 to 10:100.

[0017] Preferably, the method for preparing the coal-supported sodium iron disulfide catalyst includes the following steps:

[0018] Coal is mixed with Na2S solution or NaHS solution to obtain coal slurry;

[0019] The coal slurry and the ferric salt solution were mixed to carry out a precipitation reaction, resulting in a precipitation reaction system.

[0020] The precipitation reaction system was aged and then subjected to solid-liquid separation to obtain the sodium iron disulfide catalyst on the coal surface.

[0021] Preferably, the particle size of the coal is <0.15 mm.

[0022] This invention also provides an application of sodium iron disulfide catalyst in direct coal liquefaction, comprising the following steps:

[0023] The sodium iron disulfide catalyst, solvent, and coal are mixed and liquefied under hydrogen conditions.

[0024] The sodium iron disulfide catalyst is the sodium iron disulfide catalyst obtained by the preparation method described in the above technical solution.

[0025] This invention provides a method for preparing sodium iron sulfide catalyst, comprising the following steps: mixing a trivalent iron salt solution with a Na₂S solution or a NaHS solution to carry out a precipitation reaction, obtaining a precipitation reaction system; aging the precipitation reaction system, and obtaining the sodium iron sulfide catalyst through solid-liquid separation. The NaFeS₂ prepared by this invention is in sulfide form, eliminating the need for additional sulfur additives when used as a direct coal liquefaction catalyst. Furthermore, the preparation method of the NaFeS₂ catalyst provided by this invention is simple, uses mild preparation conditions, requires no heating or pressurization, has widely available raw materials, is low in cost, and is easily scaled up industrially.

[0026] Furthermore, this invention loads the NaFeS2 catalyst onto the surface of coal, using coal as a carrier to impregnate and adsorb the NaFeS2 catalyst onto the surface of coal particles. On the one hand, this can inhibit the agglomeration of NaFeS2 crystals and allow for better uniform mixing of the NaFeS2 catalyst during coal slurry preparation, which is beneficial for forming a small-particle-size and well-dispersed NaFeS2 catalyst. At the same time, the presence of coal helps stabilize NaFeS2, preventing it from agglomerating during its conversion to the active phase (Fe7S8). On the other hand, it allows the NaFeS2 catalyst particles to be in close contact with the coal, which is beneficial for improving the catalytic cracking effect of the NaFeS2 catalyst on coal, and can significantly improve the conversion rate and oil yield of the direct coal liquefaction reaction.

[0027] Meanwhile, this invention uses NaFeS2 as a catalyst for direct coal liquefaction, which has high catalytic activity. During the coal liquefaction process, NaFeS2 transforms into a catalytically active phase, which can promote the activation of molecular hydrogen (hydrogen in hydrogen gas) and solvent hydrogen (hydrogen in the hydrogen-donating solvent), increase the amount of active hydrogen, and achieve rapid hydrogenation stabilization of coal pyrolysis free radicals. The Na introduced in NaFeS2 can combine with oxygen-containing groups in coal or intermediate product asphaltene, promote the cracking of coal or intermediate product asphaltene, generate more free radicals, thereby improving the yield and conversion rate of direct coal liquefaction oil. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 The XRD pattern of NaFeS2 catalyst A-1 prepared in Example 1;

[0030] Figures 2-6 SEM image of NaFeS2 catalyst A-1 prepared in Example 1;

[0031] Figure 7 The Na element distribution diagram is shown for NaFeS2 catalyst A-1 prepared in Example 1;

[0032] Figure 8 The Fe elemental distribution diagram of NaFeS2 catalyst A-1 prepared in Example 1 is shown.

[0033] Figure 9 The image shows the S element distribution of NaFeS2 catalyst A-1 prepared in Example 1. Detailed Implementation

[0034] This invention provides a method for preparing a sodium iron disulfide catalyst, comprising the following steps:

[0035] A ferric salt solution is mixed with a Na₂S solution or a NaHS solution to carry out a precipitation reaction, resulting in a precipitation reaction system.

[0036] The precipitation reaction system was aged and then separated into solid and liquid phases to obtain the sodium iron disulfide catalyst.

[0037] Unless otherwise specified, all raw materials used in the preparation of this invention are preferably commercially available products well known to those skilled in the art.

[0038] This invention involves mixing an iron salt solution with a Na2S solution or a NaHS solution to carry out a precipitation reaction, thereby obtaining a precipitation reaction system.

[0039] In this invention, the ferric salt solution is preferably FeCl3 solution or Fe(NO3)3 solution; the concentration of the ferric salt solution is preferably 0.1-2.4 mol / L, more preferably 0.5-2 mol / L, and most preferably 1-1.6 mol / L; the concentrations of the Na2S solution and NaHS solution are independently preferably 0.15-1.2 mol / L, more preferably 0.2-1 mol / L, and even more preferably 0.3-0.8 mol / L.

[0040] In this invention, the molar ratio of S in the Na2S solution or NaHS solution to Fe in the ferric salt solution is preferably ≥2, more preferably 2.2 to 5.0.

[0041] In this invention, it is preferred to add a ferric salt solution dropwise to a Na₂S solution or a NaHS solution; this invention does not impose any special limitation on the dropwise acceleration rate of the ferric salt solution, and any method well known to those skilled in the art can be used; the precipitation reaction is preferably carried out under stirring conditions, and this invention does not limit the stirring rate, as long as the precipitation reaction is complete; in this invention, the temperature of the precipitation reaction is preferably 10–90°C, more preferably 20–40°C; the time is preferably 1–3 h, more preferably 2–3 h.

[0042] In this invention, the solution mixing method is used because if the iron salt and Na₂S or NaHS are both solids, and then water is added to dissolve them, the concentrations of iron ions and sulfur ions are high when a small amount of water is added. This leads to incomplete target reaction and a higher likelihood of side reactions (such as Fe). 3+ With S 2- The redox reaction between the two affects the purity of the prepared NaFeS2.

[0043] In this invention, the chemical formula of the precipitation reaction is preferably as shown in Formulas I to III:

[0044] Fe 3+ +2Na₂S→NaFeS₂+3Na + Formula I;

[0045] HS - +H₂O→H₂S+OH - Formula II;

[0046] Fe 3+ +2NaHS+2OH - →NaFeS2+Na + +2H2O Formulation III.

[0047] After obtaining the precipitation reaction system, the present invention ages the precipitation reaction system and obtains the sodium iron disulfide catalyst by solid-liquid separation.

[0048] In this invention, the aging method is preferably static aging; the aging temperature is preferably 10–40°C, more preferably 20–30°C; and the aging time is preferably 2–24 hours, more preferably 12–24 hours. This invention uses static aging to allow the precipitation reaction system to settle, facilitating subsequent separation. It also removes impurities from the precipitate and promotes the crystallization of newly formed amorphous precipitates or the growth of precipitate crystals, resulting in a uniform particle size distribution. Specifically, the impurities are mainly sodium salts, such as NaCl or NaNO3. Since fine crystals have a higher solubility than coarse crystals, during the aging process, the fine crystals gradually dissolve and deposit on the coarse crystals. In this "dissolution-deposition" process, impurities trapped in the fine crystals are also transferred into the solution, thereby achieving impurity removal.

[0049] In this invention, the solid-liquid separation method is preferably filtration or centrifugation; this invention does not have any particular limitation on the filtration or centrifugation, and any method known to those skilled in the art can be used.

[0050] In this invention, the solid after solid-liquid separation is preferably washed, dried, and ground sequentially to obtain the sodium iron sulfide catalyst; the washing is preferably water washing; the water is preferably deionized water; the number of washings is preferably 3 to 5 times, more preferably 4 times; the drying temperature is preferably 65 to 85°C, more preferably 65 to 75°C; the drying time is preferably 12 to 24 hours, more preferably 12 to 18 hours; the drying is preferably carried out under vacuum or an inert atmosphere; the inert atmosphere is preferably nitrogen, argon, or helium; the particle size of the sodium iron sulfide catalyst is preferably <125 μm, more preferably <75 μm; this invention does not have a special limitation on the grinding method, grinding to the desired particle size is sufficient.

[0051] In this invention, the sodium iron disulfide catalyst further includes a coal support, which is a coal support and sodium iron disulfide loaded on the coal support; the mass ratio of Fe to coal in the sodium iron disulfide catalyst is preferably 1 to 10:100, more preferably 2 to 8:100, and most preferably 6:100.

[0052] In this invention, the method for preparing the coal-supported sodium iron disulfide catalyst preferably includes the following steps:

[0053] Coal is mixed with Na2S solution or NaHS solution to obtain coal slurry;

[0054] The coal slurry and the ferric salt solution were mixed to carry out a precipitation reaction, resulting in a precipitation reaction system.

[0055] The precipitation reaction system was aged and then subjected to solid-liquid separation to obtain the sodium iron disulfide catalyst on the coal surface.

[0056] This invention involves mixing coal with a Na2S solution or a NaHS solution to obtain a coal slurry.

[0057] The present invention does not have any particular limitation on the way the coal is mixed with Na2S solution or NaHS solution, as long as complete mixing is achieved.

[0058] In this invention, the particle size of the coal is preferably <0.15mm, more preferably <0.075mm; in this invention, the coal is preferably low-rank coal with dry ash-free volatile matter ≥35wt%.

[0059] In this invention, the Na2S solution or NaHS solution is preferably the same as the Na2S solution or NaHS solution used in the above-mentioned method for preparing sodium iron disulfide catalyst.

[0060] After obtaining the coal slurry, the present invention mixes the coal slurry with a ferric salt solution and carries out a precipitation reaction to obtain a precipitation reaction system; the precipitation reaction system is aged and then separated into solid and liquid phases to obtain the sodium iron disulfide catalyst on the coal surface.

[0061] In this invention, the molar ratio of S in the coal slurry to Fe in the trivalent iron salt solution is preferably the same as the molar ratio of S in the Na2S solution or NaHS solution in the above-mentioned method for preparing sodium iron disulfide catalyst.

[0062] In this invention, the precipitation reaction, aging and solid-liquid separation methods are preferably consistent with those in the above-mentioned method for preparing sodium iron disulfide catalyst.

[0063] The NaFeS2 catalyst prepared by the method of the present invention is in the form of a sulfide. When used as a direct coal liquefaction catalyst, no additional sulfur additive is required. Furthermore, the preparation method of the NaFeS2 catalyst provided by the present invention is simple, the preparation conditions are mild, no heating or pressurization is required, the raw materials are widely available, the cost is low, and it is easy to scale up industrially.

[0064] This invention uses coal as a carrier, allowing NaFeS2 catalyst to be impregnated and adsorbed onto the surface of coal particles. On the one hand, this can inhibit the agglomeration of NaFeS2 crystals and enable better and more uniform mixing of the NaFeS2 catalyst during coal slurry preparation, which is beneficial for forming a small-sized and well-dispersed NaFeS2 catalyst. At the same time, the presence of coal helps stabilize NaFeS2, preventing it from agglomerating during its conversion to the active phase (Fe7S8). On the other hand, it enables close contact between the NaFeS2 catalyst particles and the coal, which is beneficial for improving the catalytic cracking effect of the NaFeS2 catalyst on coal, and can significantly improve the conversion rate and oil yield of direct coal liquefaction reaction.

[0065] This invention also provides an application of sodium iron disulfide catalyst in direct coal liquefaction, comprising the following steps:

[0066] The sodium iron disulfide catalyst, solvent, and coal are mixed and liquefied under hydrogen conditions.

[0067] The sodium iron disulfide catalyst is the sodium iron disulfide catalyst obtained by the preparation method described in the above technical solution.

[0068] In this invention, the solvent is preferably one or more of tetrahydronaphthalene, hydrogenated aromatics, and recycled solvent oil, more preferably tetrahydronaphthalene; the hydrogenated aromatics preferably include one or more of dihydrophenanthrene and dihydropyrene; the recycled solvent oil is preferably hydrotreated heavy oil produced by a coal direct liquefaction plant, preferably a medium-temperature solvent oil with a distillation range of 220–350°C; the coal is preferably low-rank coal; the dry ash-free volatile matter of the low-rank coal is preferably ≥35 wt%; the low-rank coal preferably includes lignite, sub-bituminous coal, and high-volatile bituminous coal; in a specific embodiment of this invention, the coal is from Shangwan Coal Mine of Shenhua Group Shendong Coal Group; the particle size of the coal is preferably <0.15 mm, more preferably <0.075 mm.

[0069] In this invention, the Fe content in the sodium iron disulfide catalyst is preferably 0.5-3 wt% of coal, more preferably 1-2 wt%; the mass ratio of the solvent to coal is preferably 50-70:30-50, more preferably 55-65:35-45; the initial pressure of the liquefied H2 is preferably 6-10 MPa, more preferably 7-9 MPa; the reaction temperature is preferably 420-480℃, more preferably 430-460℃; and the reaction time is preferably 40-90 min, more preferably 60-80 min.

[0070] In this invention, the conversion rate of the direct coal liquefaction is preferably 77.5-88.0%, more preferably 78.9-87.4%, and even more preferably 82.5-83.5%; the oil yield is preferably 53.1-64.6%, more preferably 56.8-62.0%, and even more preferably 59.8-61.4%.

[0071] This invention uses sodium iron sulfide as a catalyst for direct coal liquefaction. It exhibits high catalytic activity, transforming into a catalytically active phase during coal liquefaction. This phase promotes the activation of molecular hydrogen (hydrogen in hydrogen gas) and solvent hydrogen (hydrogen in the hydrogen-donating solvent), increasing the amount of active hydrogen and achieving rapid hydrogenation stabilization of free radicals from coal pyrolysis. Furthermore, the Na introduced into sodium iron sulfide can combine with oxygen-containing groups in coal or intermediate asphaltene, promoting the cracking of coal or intermediate asphaltene and generating more free radicals, thereby improving the yield and conversion rate of direct coal liquefaction oil.

[0072] To further illustrate the present invention, the preparation method of sodium iron disulfide catalyst provided by the present invention and its application in direct coal liquefaction are described in detail below with reference to the accompanying drawings and embodiments. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0073] Example 1

[0074] Measure 100 mL of 0.1 mol / L FeCl3 solution and add it dropwise to 140 mL of stirred 0.15 mol / L Na2S solution at a rate of 10 mL / min using a separatory funnel. After the FeCl3 solution is completely added, allow the precipitation reaction to proceed for 2 hours at room temperature with stirring to obtain the precipitation reaction system.

[0075] The precipitation reaction system was allowed to stand and age at room temperature for 24 hours. After centrifugation, the solid obtained was washed three times with deionized water and then dried in a vacuum oven at 65°C for 12 hours. Finally, NaFeS2 was ground with an agate mortar until the particle size was <75μm (passing through a 200-mesh sieve) to obtain the NaFeS2 catalyst, denoted as catalyst A-1.

[0076] Example 2

[0077] The NaFeS2 catalyst was prepared according to the preparation method described in Example 1, except that the concentration of the Na2S solution was 1.2 mol / L, and it was designated as catalyst A-2.

[0078] Example 3

[0079] The NaFeS2 catalyst was prepared according to the preparation method described in Example 1, except that NaFeS2 was ground to a particle size of 75-125 μm (passing through a 120-mesh sieve) using an agate mortar, and was designated as catalyst A-3.

[0080] Example 4

[0081] Weigh 10g of coal (passed through a 160-mesh sieve) and place it in 140mL of 0.15mol / L Na2S solution. Stir well to obtain a coal slurry. Measure 100mL of 0.1mol / L FeCl3 solution and add it dropwise to the coal slurry at a rate of 12mL / min using a separatory funnel. After the FeCl3 solution is added, allow the precipitation reaction to proceed for 2 hours at room temperature with stirring to obtain the precipitation reaction system.

[0082] The precipitation reaction system was allowed to stand and age at room temperature for 12 hours. After centrifugation, the solid obtained was washed three times with deionized water and then dried in a vacuum oven at 85°C for 12 hours. Finally, NaFeS2 was ground with an agate mortar until the particle size was <75μm (passing through a 200-mesh sieve) to obtain the NaFeS2 catalyst, denoted as catalyst A-4.

[0083] Comparative Example 1

[0084] The "863 catalyst" (containing promoter S) used industrially by Shenhua Coal-to-Liquid Company is denoted as catalyst B-1. The "863 catalyst" is nanoscale hydrated iron oxide γ-FeOOH with a particle length of 60 - 150 nm and a width of 20 - 50 nm, and this catalyst is dispersed on the surface of pulverized coal with a particle size < 0.15 mm.

[0085] Comparative Example 2

[0086] Use an agate mortar to grind FeS2 with a purity > 99.9% to a particle size < 75 μm (pass through a 200-mesh sieve), and denote it as catalyst B-2.

[0087] Test Example 1

[0088] Use a D8 Advance X-ray diffractometer from Bruker, Germany to conduct XRD tests on the catalyst A-1 prepared in Example 1. The test conditions are: test voltage 40 kV, test current 40 mA, with Cu-Kα as the radiation source, and collect diffraction peaks from 10 - 60° at a scanning speed of 2° / min. The results are as Figure 1 shown. It can be seen from Figure 1 that the main diffraction peaks of the synthesized product correspond to the standard card of the NaFeS2 crystal phase, and there are no other crystal phases, indicating that the main composition of the synthesized product is NaFeS2.

[0089] Use a QUANTA450 tungsten filament scanning electron microscope from FEI, USA to observe the morphological characteristics of the catalyst A-1 prepared in Example 1, with an acceleration voltage of 20 kV. The results are as Figures 2-5 shown. It can be seen from Figures 2-5 that the NaFeS2 catalyst particles prepared in this invention are in the shape of a rhombic prism.

[0090] Use a scanning electron microscope to observe the catalyst A-1 prepared in Example 1, and use an EDS device配套 with the scanning electron microscope to measure the element distribution in the catalyst A-1 prepared in Example 1. The results are as Figures 6-9 shown. It can be seen from Figures 6-9 that Na, Fe, and S elements are evenly distributed throughout the particles.

[0091] Test Example 2

[0092] The direct coal liquefaction catalytic performance of the catalysts prepared in Examples 1-4 and Comparative Examples 1-2 was tested in a 35 mL tubular bomb reactor. The specific steps were as follows: Shangwan coal (passed through a 160-mesh sieve) from the Shangwan Coal Mine of Shenhua Group Shendong Coal Group was added to the reactor at a dry ash-free mass ratio of tetrahydronaphthalene to Shangwan coal of 65:35, with the iron content in the catalysts of Examples 1-4 and Comparative Examples 1-2 being 1 wt% of the coal content. The reaction was carried out at an initial H2 pressure of 7.0 MPa and 450 °C for 60 min. After the reaction, the reactor was rapidly cooled to 20 °C, and the gas in the reactor was collected and its composition analyzed. The liquid and solid products in the reactor were collected and subjected to Soxhlet extraction sequentially with n-hexane, toluene, and tetrahydrofuran. The direct coal liquefaction conversion rate and the yield of each product were calculated based on the obtained data, and the results are shown in Table 1.

[0093] Table 1. Results of the catalytic performance of the catalysts prepared in Examples 1-4 and Comparative Examples 1-2 for direct coal liquefaction.

[0094]

[0095]

[0096] Among them, gas refers to the gaseous products generated during the direct liquefaction reaction of coal, mainly including CO, CO2, CH4, C2H4, C2H6, C3H6, C3H8 and H2S.

[0097] As can be seen from Example 1 and Comparative Example 1, NaFeS2 has high catalytic activity as a direct coal liquefaction catalyst, and its direct coal liquefaction conversion rate and oil yield are significantly higher than those of Shenhua 863 catalyst.

[0098] As can be seen from Examples 1 and 2, when the concentration of the reagent used to synthesize NaFeS2 changes, the catalytic performance of NaFeS2 also changes. This is because the reagent concentration affects the texture properties (such as specific surface area, pore volume, etc.) of the synthesized NaFeS2.

[0099] Examples 1 and 3 show that as the particle size of NaFeS2 increases, its catalytic activity for direct coal liquefaction decreases, indicating that particle size is one of the important factors affecting the catalytic performance of NaFeS2. Meanwhile, compared to Comparative Example 2, even though the catalyst in Example 3 had a larger particle size, its activity was higher, indicating that Na plays a role in the NaFeS2-catalyzed direct coal liquefaction reaction.

[0100] As can be seen from Examples 1 and 4, the conversion rate of NaFeS2 directly loaded on the coal sample is significantly higher than that of unloaded NaFeS2, but the oil yields are similar.

[0101] As shown in Examples 1-3 and Comparative Example 2, the conversion rate and oil yield of NaFeS2 containing Na as a direct coal liquefaction catalyst are significantly higher than those of FeS2 catalyst without Na. This indicates that Na plays a role in the direct coal liquefaction reaction catalyzed by NaFeS2, promoting the liquefaction conversion of coal and significantly improving the oil yield.

[0102] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. The application of a sodium iron disulfide catalyst in direct coal liquefaction, characterized in that, Includes the following steps: The sodium iron disulfide catalyst, solvent, and coal are mixed and liquefied under hydrogen conditions. The sodium iron sulfide catalyst further includes a coal support, comprising a coal support and sodium iron sulfide supported on the coal support; the mass ratio of Fe to coal in the sodium iron sulfide catalyst is 1~10:100, and the preparation method of the sodium iron sulfide catalyst containing a coal support includes the following steps: Coal is mixed with Na2S solution or NaHS solution to obtain coal slurry; The coal slurry and the ferric salt solution were mixed to carry out a precipitation reaction, resulting in a precipitation reaction system. The precipitation reaction system was aged and then subjected to solid-liquid separation to obtain a sodium iron disulfide catalyst with a coal support. The precipitation reaction is carried out under stirring conditions; the precipitation reaction temperature is 20~40℃ and the time is 1~3h; the aging temperature is 10~40℃ and the time is 2~24h.

2. The application according to claim 1, characterized in that, The concentration of the ferric salt solution is 0.1~2.4 mol / L; The concentrations of the Na₂S solution and the NaHS solution are independently 0.15~1.2 mol / L.

3. The application according to claim 1 or 2, characterized in that, The molar ratio of S in the Na2S solution or NaHS solution to Fe in the ferric salt solution is ≥2.

4. The application according to claim 1, characterized in that, The solid-liquid separation process further includes grinding the sodium iron disulfide catalyst to a particle size of <125μm.

5. The application according to claim 1, characterized in that, The coal has a particle size of <0.15mm.

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