Recycled hydrogen-donating solvent for direct coal liquefaction, method for preparing the same, and use thereof

Abstract

The present invention provides a recycled hydrogen-donating solvent for directly liquefying coal, a method for preparing the same, and its use. By using the preparation method of the present invention to provide a recycled hydrogen-donating solvent, a recycled hydrogen-donating solvent having good hydrogen-donating ability can be obtained by a relatively simple process flow. The preparation method includes the following steps: 1) performing a first fractionation on the direct coal liquefaction oil to obtain a liquefied middle oil and a liquefied heavy oil; 2) supplying the liquefied heavy oil to a first hydrogenation reactor to perform a first-stage hydrogenation reaction; 3) supplying the liquefied middle oil and the liquefied heavy oil that has undergone the first-stage hydrogenation reaction in step 2) to a second hydrogenation reactor to perform a second-stage hydrogenation reaction to obtain a hydrogenated product oil; 4) performing a second fractionation on the hydrogenated product oil to obtain a medium-temperature solvent oil and a high-temperature solvent oil; and 5) mixing the medium-temperature solvent oil and the high-temperature solvent oil to prepare a recycled hydrogen-donating solvent.

Description

Detailed description of the invention

[0001] [Technical Field] The present invention relates to the technical field of direct coal liquefaction, and more particularly to a recycled hydrogen-donating solvent for direct coal liquefaction, a method for preparing the same, and its use.

[0002] [Background technology] The direct coal liquefaction process involves mixing coal powder, solvent oil, and catalysts into a coal slurry, then mixing it with hydrogen. This mixed slurry is sequentially supplied to a coal slurry preheater and a coal liquefaction reactor, where it is reacted under specific conditions (reaction temperature of 400-480°C and reaction pressure of 10-30 MPa). The reaction products are then separated using a separation system to obtain gaseous products, liquefied oil products, and solid oil residue, respectively.

[0003] In existing direct coal liquefaction processes, solvents not only have physical effects such as slurring solid coal powder to improve material transport and thermodynamic properties and dissolving coal pyrolysis products, but also important chemical effects in the direct coal liquefaction reaction process, such as supplying hydrogen to coal pyrolysis products and stabilizing low molecular weight pyrolysis products. Direct coal liquefaction solvents possess not only the functions of a general solvent but also excellent hydrogen donating and transport capabilities. Therefore, the hydrogen donating capacity of solvents plays an important role in easing reaction conditions and improving the oil yield in direct coal liquefaction.

[0004] In the continuous operation process of a direct coal liquefaction plant, the solvent used is a mixture of medium-temperature oil and high-temperature oil produced from the direct coal liquefaction itself in a fixed ratio, and is called a recycled solvent. Its main components are 2- to 4-ring aromatic hydrocarbons and hydrogenated aromatic hydrocarbons. Because recycled solvents prepared from liquefied crude oil have a low hydrogen content, a high aromatic carbon ratio, and poor hydrogen donating capacity, the conventional method to improve the hydrogen donating capacity of the solvent oil has been to perform hydrogenation treatment to an appropriate depth on the recycled solvent.

[0005] Therefore, those skilled in the art have conducted much research to obtain recycled solvents with superior hydrogen-donating capacity for direct coal liquefaction. Among these, the processing characteristics of recycled solvents in Japan's NEDOL process involve using a portion of the distilled coal liquefied oil produced in the coal liquefaction unit as a feed material for a hydrogenation plant using a Ni-Mo catalyst. The processing characteristics of recycled solvents in China's Shenhua coal direct liquefaction process (Publication No. CN1257252C) involve using the entire fraction of coal liquefied oil produced in the coal liquefaction unit as a feed material for the hydrogenation plant, and using the cut heavy distillate oil as a recycled solvent, with the hydrogenation plant using a Ni-Mo catalyst. CN1844318A discloses a hydrogenation process for recycled solvents for direct liquefaction and provides catalyst gradation technology for a coal direct liquefaction whole fraction oil hydrogenation process that obtains a recycled hydrogen-donating solvent under appropriate chemical reaction conditions. In CN104194830, fractional distillation is first performed on the direct liquefied coal oil, selectively cutting off the heavy oil fraction. Then, the heavy oil fraction with a narrow distribution is hydrogenated and stabilized to obtain a direct liquefied coal recycling solvent with relatively good hydrogen donating capacity. In CN106479564A, the total distillate of direct liquefied coal oil is cut to obtain medium-temperature oil and high-temperature oil. The different fractions obtained by the cutting are hydrogenated separately, and the hydrogenated oils are mixed to obtain a recycling solvent. The recycling solvent prepared with this solution has advantages such as low hydrogen consumption, low gas yield, and high hydrogen donating capacity.

[0006] However, the recycled solvents for direct coal liquefaction obtained by the aforementioned processing methods have technical problems such as high hydrogen consumption, strict process conditions, insufficient hydrogen supply capacity, and / or complex technical process flows. Therefore, it is necessary to improve the processing methods for existing recycled solvents.

[0007] [Summary of the Invention] The present invention provides a recycled hydrogen-donating solvent for direct coal liquefaction, a method for preparing the same, and its use. The present invention can provide a recycled hydrogen-donating solvent with good hydrogen-donating ability through a relatively simple process flow.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] The present invention provides a method for preparing a recycled hydrogen-donating solvent for direct coal liquefaction, and the method includes the following steps: 1) Performing a first fractionation on direct coal liquefaction oil to obtain liquefied middle oil and liquefied heavy oil, wherein the liquefied middle oil is the distillate oil at 220 to 320 °C, and the liquefied heavy oil is the distillate oil exceeding 320 °C; 2) Supplying the liquefied heavy oil to a first hydrogenation reactor to perform a first-stage hydrogenation reaction; 3) Supplying the liquefied middle oil and the liquefied heavy oil subjected to the first-stage hydrogenation reaction in step 2) to a second hydrogenation reactor to perform a second-stage hydrogenation reaction to obtain a hydrogenated product oil; 4) Performing a second fractionation on the hydrogenated product oil to obtain a medium-temperature solvent oil and a high-temperature solvent oil, wherein the medium-temperature solvent oil is the distillate oil at 220 to 350 °C, and the high-temperature solvent oil is the distillate oil exceeding 350 °C; and 5) Mixing the medium-temperature solvent oil and the high-temperature solvent oil to prepare the recycled hydrogen-donating solvent. In a preferred embodiment, in step 2), the first hydrogenation reactor is a suspended-bed hydrogenation reactor, and in step 3), the second hydrogenation reactor is a fixed-bed hydrogenation reactor.

[0010] In some embodiments, in step 2), the first-stage hydrogenation reaction has a reaction temperature I of 350 to 400 °C, a volume space velocity I of 0.5 to 3 h -1 , a volume ratio of hydrogen to oil I of 400 to 2000:1 (Nm 3 / m 3) and preferably, it is carried out under the condition that the reaction pressure I is 12 to 20 MPa. Here, the volume ratio I of hydrogen to oil means the volume ratio of the hydrogen introduced into the first hydrogenation reactor in step 2) to the feedstock oil (i.e., liquefied heavy oil) of this step.

[0011] In step 3), the second-stage hydrogenation reaction has a reaction temperature II of 320 to 380 °C, a volume space velocity II of 0.5 to 3 h -1 , a volume ratio II of hydrogen to oil of 400 to 1600:1 (Nm 3 / m 3 ) and preferably, it is carried out under the condition that the reaction pressure II is 12 to 20 MPa. Here, the volume ratio II of hydrogen to oil is the volume ratio of the hydrogen introduced into the second hydrogenation reactor in step 3) to the feedstock oil of this step (i.e., the liquefied heavy oil subjected to the first-stage hydrogenation reaction in step 2).

[0012] Furthermore, the reaction temperature I is higher than the reaction temperature II, the volume space velocity I is not less than the volume space velocity II, and the volume ratio I of hydrogen to oil is not less than the volume ratio II of hydrogen to oil. Preferably, the volume space velocity I is higher than the volume space velocity II, and the volume ratio I of hydrogen to oil is higher than the volume ratio II of hydrogen to oil.

[0013] In a preferred embodiment, in step 2), the first-stage hydrogenation reaction has a reaction temperature I of 360 to 390 °C, such as 360 °C, 370 °C, 380 °C, and 390 °C, etc., a volume space velocity I of 0.8 to 2.5 h -1 , such as 0.8 h -1 , 1.0 h -1 , 1.5 h -1 , 2.0 h -1 , and 2.5 h -1 etc., a volume ratio I of hydrogen to oil of 500 to 1200:1 (Nm 3 / m 3The reaction is carried out under conditions where the reaction pressure I is between 13 and 19 MPa, for example, 13 MPa, 14 MPa, 15 MPa, 16 MPa, 17 MPa, 18 MPa, and 19 MPa, with reaction ratios such as 500:1, 600:1, 700:1, 800:1, 900:1, 1000:1, 1100:1, and 1200:1.

[0014] In step 3), the second stage hydrogenation reaction occurs at a reaction temperature II of 340-370°C, for example, 340°C, 350°C, 360°C, and 370°C, with a volume space velocity II of 0.8-2 h. -1 For example, 0.8h -1 , 1.0h -1 , 1.5h -1 , and 2.0h -1 For example, the volume ratio of hydrogen to oil II is 500-1200:1 (Nm³). 3 / m 3 ), for example, 500:1, 600:1, 700:1, 800:1, 900:1, 1000:1, 1100:1, and 1200:1, and the reaction is carried out under conditions where the reaction pressure II is 13 to 19 MPa, for example, 13 MPa, 14 MPa, 15 MPa, 16 MPa, 17 MPa, 18 MPa, and 19 MPa.

[0015] Furthermore, the reaction temperature I is higher than the reaction temperature II, the volume space velocity I is higher than the volume space velocity II, and the volume ratio I of hydrogen to oil is higher than the volume ratio II of hydrogen to oil.

[0016] In some embodiments, the first hydrogenation reaction is carried out in the presence of a first hydrogenation catalyst, and the second hydrogenation reaction is carried out in the presence of a second hydrogenation catalyst.

[0017] The first hydrogenation catalyst comprises a first support and a first active component. The second hydrogenation catalyst comprises a second support and a second active component.

[0018] The first active component and the second active component are each independently one or more selected from oxides of group VIB metal elements and oxides of group VIII metal elements, preferably the group VIB metal element is selected from Mo and / or W, and the group VIII metal element is selected from Co and / or Ni.

[0019] Preferably, the first carrier and the second carrier are each independently one or more selected from alumina, Y-type molecular sieves, and β-type molecular sieves. In some embodiments, the first hydrogenation catalyst contains the first support in an amount of 60 to 90% by weight, and the first active component in an amount of 10 to 40% by weight.

[0020] In the second hydrogenation catalyst, the second support is contained in an amount of 60 to 90% by weight, and the second active component is contained in an amount of 10 to 40% by weight.

[0021] In some embodiments, the first active component and the second active component are, independently, a combination of an oxide of a group VIB metal element and an oxide of a group VIII metal element.

[0022] Preferably, the first hydrogenation catalyst contains an oxide of a group VIB metal element in an amount of 10 to 35% by weight and an oxide of a group VIII metal element in an amount of 4 to 10% by weight.

[0023] Preferably, the second hydrogenation catalyst contains oxides of group VIB metal elements in an amount of 10 to 30% by weight, and oxides of group VIII metal elements in an amount of 1 to 6% by weight.

[0024] In a preferred embodiment, in step 5), the mass ratio of the medium-temperature solvent oil to the high-temperature solvent oil is 4:1 to 1:3, for example, 4:1, 3:1, 2:1, 1:1, 1:2, and 1:3. Preferably, it is 1:1 to 3.5:1, for example, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, and 3.5:1. More preferably, it is 2.5:1 to 3.5:1.

[0025] The present invention also provides a recyclable hydrogen-donating solvent prepared by the above-described preparation method.

[0026] The present invention also provides a method for direct coal liquefaction, in which the aforementioned recycled hydrogen-donating solvent is used.

[0027] The present invention has the following beneficial effects: The present invention makes it possible to provide a recyclable hydrogen-donating solvent with good hydrogen-donating ability through a relatively simple process flow. By employing the preparation method according to the present invention, the present invention can provide a recyclable hydrogen-donating solvent that can effectively improve the hydrogen-donating capacity of the recyclable hydrogen-donating solvent without requiring complex preparation steps and harsh process conditions. The recyclable hydrogen-donating solvent according to the present invention has a wide distillation range and good swelling ability for coal powder. When the recyclable hydrogen-donating solvent according to the present invention is used in the direct coal liquefaction process, a coal slurry with lower viscosity can be obtained, which is convenient for transportation. The process flow for preparing the recyclable hydrogen-donating solvent according to the present invention is simple and can be easily implemented in an industrial plant. [Description of the drawing]

[0028] Figure 1 is a schematic diagram showing the flow of the preparation process for a recyclable hydrogen-donating solvent according to one embodiment. [Detailed explanation]

[0029] The present invention will be further described below in conjunction with embodiments to facilitate understanding of the invention. It should be understood that the following embodiments are provided solely for the purpose of better understanding the invention and do not imply that the invention is limited thereto.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in which the invention pertains. The terms “and / or” as used herein include any and all combinations of one or more related enumerated items. Terms such as “first,” “second,” and “third” are used for descriptive purposes only and are not intended to indicate or imply relative importance.

[0031] In embodiments where specific experimental procedures or conditions are not explicitly stated, they may be carried out according to operations or conditions corresponding to conventional experimental procedures in the art. Reagents or equipment whose manufacturers are not specified are commercially available conventional products.

[0032] One aspect of the present invention provides a method for preparing a recycled hydrogen-donating solvent for direct coal liquefaction, comprising the following steps: 1) A first fractional distillation is performed on the directly liquefied coal oil to obtain liquefied medium-grade oil and liquefied heavy-grade oil. Here, the liquefied medium-grade oil is distillate at 220-320°C, and the liquefied heavy-grade oil is distillate at over 320°C; 2) A step of supplying the liquefied heavy oil to the first hydrogenation reactor and carrying out the first stage of the hydrogenation reaction. 3) A step in which the liquefied medium oil and the liquefied heavy oil subjected to the first stage hydrogenation reaction in step 2) are supplied to a second hydrogenation reactor, and the second stage hydrogenation reaction is carried out to obtain hydrogenated oil. 4) A second fractional distillation of the hydrogenated oil to obtain a medium-temperature solvent oil and a high-temperature solvent oil, wherein the medium-temperature solvent oil is a distillate at 220-350°C, and the high-temperature solvent oil is a distillate at over 350°C; and 5) A step of mixing the medium-temperature solvent oil and the high-temperature solvent oil to prepare the recycled hydrogen donating solvent.

[0033] The present invention provides a method for preparing a recycled hydrogen-donating solvent for direct coal liquefaction. This method involves first performing a first-stage hydrogenation reaction on a liquefied heavy oil at a temperature exceeding 320°C obtained by fractional distillation of the direct coal liquefaction oil, and then subjecting this to a second-stage hydrogenation reaction together with a liquefied medium-temperature oil at 220-320°C. This method effectively solves the problems of insufficient or excessive hydrogenation in the prior art. The hydrogenated oil obtained from the hydrogenation treatment is fractionally distilled to obtain a medium-temperature solvent oil at 220-350°C and a high-temperature solvent oil exceeding 350°C, which are then blended to obtain a recycled hydrogen-donating solvent. When this recycled hydrogen-donating solvent is used in the direct coal liquefaction process, it not only has high hydrogen-donating capacity but also a wide distillation range, effectively swelling coal powder and reducing the viscosity of the coal slurry, thereby contributing to improving the effectiveness of direct coal liquefaction.

[0034] The recycled hydrogen-donating solvent provided by the preparation method according to the present invention has a high content of bicyclic hydrogenated aromatic hydrocarbons and tricyclic hydrogenated aromatic hydrocarbons, and the resulting recycled hydrogen-donating solvent has superior hydrogen-donating ability. In some embodiments, the recycled hydrogen-donating solvent according to the present invention has a bicyclic hydrogenated aromatic hydrocarbon content of 10 to 40% by weight and a tricyclic hydrogenated aromatic hydrocarbon content of 5 to 20% by weight.

[0035] The preparation method according to the present invention has a simple process flow, is easy to implement industrially, and can effectively reduce the complexity of the processing process while improving the hydrogen-donating capacity of the recycled hydrogen-donating solvent. Specifically, in a preferred embodiment, in step 2), the first hydrogenation reaction is preferably carried out in a suspended bed hydrogenation reactor, and in step 3), the second hydrogenation reaction is preferably carried out in a fixed bed hydrogenation reactor.

[0036] Compared to the case where the liquefied heavy oil is directly introduced into a fixed-bed hydrogenation reactor to carry out the hydrogenation reaction, by first introducing the liquefied heavy oil into a suspended-bed hydrogenation reactor to carry out the first stage of the hydrogenation reaction, it is possible to effectively prevent impurities contained in the liquefied heavy oil from contaminating the fixed-bed reactor and catalyst, and effectively avoid adverse effects on hydrogenation efficiency and process operation stability. Furthermore, since the liquefied heavy oil is first subjected to the first stage of hydrogenation treatment in the suspended-bed reactor and then sequentially subjected to the second stage of hydrogenation treatment in the fixed-bed reactor, the reaction residence time is relatively longer compared to a single-stage hydrogenation treatment, and insufficient hydrogenation of the liquefied heavy oil can be effectively prevented. At the same time, since the liquefied heavy oil is first subjected to the first stage of hydrogenation (treatment) in the suspended-bed reactor and then subjected to the second stage of hydrogenation (treatment) together with liquefied medium-grade oil in the fixed-bed reactor, overhydrogenation of the liquefied medium-grade oil and underhydrogenation of the liquefied heavy oil are less likely to occur. Furthermore, the recycled hydrogen-donating solvent according to the present invention can not only effectively improve the hydrogen-donating capacity of the recycled hydrogen-donating solvent, but also avoid the need for harsher hydrogenation (processing) conditions and increased complexity of the hydrogenation process flow due to improved hydrogen-donating capacity. By subjecting the liquefied heavy oil to the first stage of hydrogenation in a suspended bed reactor, and then continuously subjecting it to the second stage of hydrogenation together with the liquefied medium oil in a fixed bed reactor, the advantages of processing inferior raw materials by suspended bed hydrogenation (processing) are maintained. On the other hand, by combining it with the fixed bed reactor, hydrogenation efficiency can be improved, the lifespan of the catalyst in the fixed bed reactor can be extended, and risks such as catalyst clogging, catalyst deactivation, and clogging of the fixed bed reactor due to impurities in the liquefied heavy oil can be reduced. In addition, the stability of process operations can be improved and the operating pressure difference of the plant can be reduced.

[0037] By employing the preparation method according to the present invention, the liquefied heavy oil is first subjected to the first stage of hydrogenation, and then subjected to the second stage of hydrogenation together with the liquefied medium oil. Different hydrogenation conditions can be flexibly used for the first and second stages of hydrogenation, which contributes to reducing the energy consumption and hydrogen consumption required in the processing process of the recyclable hydrogen-donating solvent.

[0038] In a preferred embodiment, in step 2), the first hydrogenation reaction is carried out under the following conditions: reaction temperature I is 350-400°C, and volume space velocity I is 0.5-3h. -1 The volume ratio I of hydrogen to oil is 400-2000:1 (Nm³ 3 / m 3 ), and preferably, the reaction pressure I is 12 to 20 MPa; in step 3), the hydrogenation reaction of the second stage is carried out under the following conditions: reaction temperature II is 320 to 380°C, and volume space velocity II is 0.5 to 3 h -1 The volume ratio of hydrogen to oil is 400-1600:1 (Nm³). 3 / m 3 ), preferably a reaction pressure II of 12 to 20 MPa; furthermore, the reaction temperature I is higher than the reaction temperature II, the volume space velocity I is greater than or equal to the volume space velocity II, and the volume ratio I of hydrogen to oil is greater than or equal to the volume ratio II of hydrogen to oil, preferably, the volume space velocity I is higher than the volume space velocity II, and the volume ratio I of hydrogen to oil is higher than the volume ratio II of hydrogen to oil. In the preparation method according to the present invention, the first and second hydrogenation reactions are carried out under the above conditions, the first hydrogenation reaction uses relatively harsh hydrogenation conditions compared to the second hydrogenation reaction, and the second hydrogenation reaction uses relatively mild hydrogenation conditions, thereby allowing for a greater increase in the content of hydrogenated aromatic hydrocarbons in the recycled hydrogen-donating solvent, avoiding overhydrogenation and underhydrogenation, and contributing to further improving the hydrogen-donating capacity of the recycled hydrogen-donating solvent.

[0039] In some preferred embodiments, in step 2), the first hydrogenation reaction is carried out under the following conditions: reaction temperature I is 360-390°C, and volume space velocity I is 0.8-2.5 h. -1 The volume ratio I of hydrogen to oil is 500-1200:1 (Nm³ 3 / m 3Step 3) The hydrogenation reaction of the second stage is carried out under the following conditions: reaction temperature II is 340-370°C, and volume space velocity II is 0.8-2h. -1 The volume ratio of hydrogen to oil II is 500-1200:1 (Nm³ 3 / m 3 ), the reaction pressure II is 13-19 MPa; furthermore, the reaction temperature I is higher than the reaction temperature II, the volume space velocity I is higher than the volume space velocity II, and the volume ratio I of hydrogen to oil is higher than the volume ratio II of hydrogen to oil. By adopting the above preferred hydrogenation treatment conditions, it is possible to further improve the hydrogen-donating capacity of the hydrogen-donating solvent for recycling, and to obtain a hydrogen-donating solvent for recycling with excellent hydrogen-donating capacity.

[0040] In the present invention, "I" and "II" in terms such as reaction temperature I, reaction temperature II, volume space velocity I, volume space velocity II, volume ratio of hydrogen to oil I, and volume ratio of hydrogen to oil II are merely convenient terms used to distinguish and explain the respective reaction conditions of the first-stage hydrogenation reaction and the second-stage hydrogenation reaction.

[0041] In the preparation method according to the present invention, the first and second hydrogenation reactions may use corresponding catalysts commonly used in the coal direct liquefied oil hydrogenation process in the art. In some embodiments, the first hydrogenation reaction is carried out in the presence of a first hydrogenation catalyst, and the second hydrogenation reaction is carried out in the presence of a second hydrogenation catalyst; the first hydrogenation catalyst comprises a first carrier and a first active component; the second hydrogenation catalyst comprises a second carrier and a second active component; the first active component and the second active component are each independently one or more selected from oxides of group VIB metal elements and oxides of group VIII metal elements. Preferably, the first carrier and the second carrier are each independently one or more selected from alumina, Y-type molecular sieves and β-type molecular sieves.

[0042] Preferably, the group VIB metal element is selected from Mo and / or W; and the group VIII metal element is selected from Co and / or Ni. More preferably, the group VIB metal element in the first hydrogenation catalyst is selected from Mo and W; and preferably, the first active component in the first hydrogenation catalyst is an oxide of Ni, Mo, and W; and more preferably, the second active component in the second hydrogenation catalyst is an oxide of Ni and Mo, or an oxide of Ni, Mo, and W, embodied as a Ni-Mo binary active metal or a Ni-Mo-W ternary active metal.

[0043] In some embodiments, in the first hydrogenation catalyst, the content of the first support is 60-90% by weight, and the content of the first active component is 10-40% by weight; and in the second hydrogenation catalyst, the content of the second support is 60-90% by weight, and the content of the second active component is 10-40% by weight. In some preferred embodiments, the first active component and the second active component are each independently a combination of an oxide of a group VIB metal element and an oxide of a group VIII metal element; preferably, in the first hydrogenation catalyst, the content of the group VIB metal element oxide is 10-35% by weight, and the content of the group VIII metal element oxide is 4-10% by weight; and preferably, in the second hydrogenation catalyst, the content of the group VIB metal element oxide is 10-30% by weight, and the content of the group VIII metal element oxide is 1-6% by weight. The use of the first and second hydrogenation catalysts of the aforementioned composition contributes to improving the catalytic activity of the first and second hydrogenation reactions.

[0044] In some embodiments, the first hydrogenation catalyst is 200 m 2 The first hydrogenation catalyst has a specific surface area of ​​0.3 ml / g or more, a pore volume of 0.3 ml / g or more, and a pore diameter of 6 nm or more, and preferably the first hydrogenation catalyst is 200 to 300 mm 2 It has a specific surface area of ​​0.35 to 0.5 ml / g, a pore volume of 0.35 to 0.5 ml / g, and a pore diameter of 7 nm or more. In some embodiments, the second hydrogenation catalyst is 150 m2 The second hydrogenation catalyst has a specific surface area of ​​0.24 ml / g or more, a pore volume of 0.24 ml / g or more, and a pore diameter of 4 nm or more, and preferably the second hydrogenation catalyst has a specific surface area of ​​180-260 nm. 2 It has a specific surface area of ​​0.25-0.45 ml / g, a pore volume of 0.25-0.45 ml / g, and a pore diameter of 5 nm or larger.

[0045] The first and second hydrogenation catalysts having the aforementioned composition and properties may be corresponding catalysts commercially available in the art, or corresponding catalysts that can be prepared using catalyst preparation techniques disclosed in the prior art. Specifically, in some embodiments, the first hydrogenation catalyst is, for example, an FFT-2 ​​catalyst supplied by the Dalian Chemical Industry Research Institute, and the second hydrogenation catalyst is, for example, an HTS-358 type catalyst supplied by the AXENS Institute in France, and so on.

[0046] In some embodiments, the active components in the first and second hydrogenation catalysts catalyze the first and second hydrogenation reactions in a vulcanized state. Specifically, for example, after filling the hydrogenation reactor with the corresponding hydrogenation catalyst, the catalyst is vulcanized using a vulcanizing agent such as carbon disulfide or dimethyl disulfide. The vulcanization of the hydrogenation catalyst is prior art in this field, and a detailed explanation is omitted here.

[0047] In a preferred embodiment, in step 5), the mass ratio of the medium-temperature solvent oil to the high-temperature solvent oil is 4:1 to 1:3, preferably 1:1 to 3.5:1, and more preferably 2.5:1 to 3.5:1. The medium-temperature solvent oil and high-temperature solvent oil obtained in the present invention are blended according to preferred ratios as recyclable hydrogen-donating solvents and have excellent hydrogen-donating properties when applied to a direct coal liquefaction process, improving the coal conversion rate and oil yield in the direct coal liquefaction process, while simultaneously reducing the asphalt yield and gas yield.

[0048] In a preferred embodiment, in the preparation method according to the present invention, in step 2), the hydrogenation reaction of the first step is carried out under the following conditions: reaction temperature I of 360-390°C, 0, and volume space velocity I of 0.8-2.5 h. -1 The volume ratio I of hydrogen to oil is 500-1200:1 (Nm³ 3 / m 3 ), the reaction pressure I is 13-19 MPa; in step 3), the hydrogenation reaction of the second stage proceeds with a reaction temperature II of 340-370°C and a volume space velocity II of 0.8-2 h -1 The volume ratio of hydrogen to oil is 500-1200:1 (Nm³). 3 / m 3 ), the reaction is carried out under conditions where the reaction pressure II is 13 to 19 MPa; furthermore, the reaction temperature I is higher than the reaction temperature II, the volume space velocity I is higher than the volume space velocity II, and the volume ratio of hydrogen to oil I is higher than the volume ratio of hydrogen to oil II. On the other hand, in step 5), the mass ratio of the medium-temperature solvent oil to the high-temperature solvent oil is 1:1 to 3.5:1, more preferably 2.5:1 to 3.5:1. Adopting this preferred embodiment not only reduces the amount of hydrogen consumed during the hydrogenation process, but also makes it possible to achieve better hydrogen-donating properties of the resulting recycled hydrogen-donating solvent, and further significantly improves the coal conversion rate and oil yield.

[0049] In some embodiments, in step 1) of the preparation method according to the present invention, the first fractional distillation is carried out in a distillation column or rectification column. The first fractional distillation is preferably carried out under conditions of an operating pressure of 0.1 to 0.8 MPa, an operating temperature at the bottom of the column of 300 to 380°C, and an operating temperature at the top of the column of 80 to 200°C. From the coal direct liquefied oil, the first fractional distillation yields liquefied light oil (distillate at less than 200°C), liquefied medium oil, and liquefied heavy oil. Of these, the liquefied light oil can be sent to downstream hydrogenators and upgrading units for the production of naphtha and diesel products, while the liquefied medium oil and liquefied heavy oil are sent to the subsequent steps 2) and 3).

[0050] In some embodiments, in step 4) of the preparation method according to the present invention, the second fractional distillation is carried out in a rectification column. Preferably, the second fractional distillation is carried out under conditions where the operating pressure of the rectification column is 0.1 to 0.8 MPa, the operating temperature at the bottom of the column is 300 to 380°C, and the operating temperature at the top of the column is 120 to 220°C. The second fractional distillation yields hydrogenated light oil (distillate oil with a distillation range of less than 220°C), the medium-temperature solvent oil, and the high-temperature solvent oil, which are used in the preparation of the recycled hydrogen-donating solvent of the present invention.

[0051] By using the preparation method according to the present invention, the recycled hydrogen-donating solvent can be prepared, and 1) as many hydrogenated aromatic hydrocarbons as possible can be obtained, which have good hydrogen-donating ability, and furthermore, the recycled hydrogen-donating solvent has a wide distillation range and good swelling ability for coal powder. When this is applied to a direct coal liquefaction process, a coal slurry with lower viscosity is obtained, which is convenient for transport. 2) The preparation process flow of the recycled hydrogen-donating solvent is simple and can be easily carried out in an industrial plant. 3) In the preparation method according to the present invention, the liquefied heavy oil is first subjected to a first-stage hydrogenation reaction, and then subjected to a second-stage hydrogenation reaction together with the liquefied medium oil, and the liquefied heavy oil undergoes the second-stage hydrogenation reaction. Furthermore, in the hydrogenation of the liquefied heavy oil and the liquefied medium oil during the hydrogenation process, different degrees of harshness of hydrogenation conditions can be flexibly adopted, maximizing the content of hydrogenated aromatic hydrocarbons in the resulting recycled solvent and avoiding over-hydrogenation and under-hydrogenation. Moreover, compared to existing hydrogenation processes for direct coal liquefied oil, the preparation method according to the present invention can effectively reduce the harshness of hydrogenation and hydrogen consumption, and has good economic efficiency and operational stability. 4) In the process of preparing the recycled hydrogen-donating solvent, the liquefied light oil is extracted from the direct coal liquefied oil. This portion of the oil is easy to hydrogenate and can be sent to the subsequent production process unit, thereby increasing the process efficiency of the recycled hydrogen-donating solvent. The hydrogenated light oil at temperatures below 220°C is extracted from the resulting hydrogenated oil, avoiding adverse effects such as a decrease in reactor utilization efficiency due to the gasification of this portion during the liquefaction process.

[0052] The present invention also provides a recyclable hydrogen-donating solvent prepared using the above-described preparation method. The present invention also provides a method for directly liquefying coal, wherein the recycled hydrogen-donating solvent is used in the direct coal liquefaction method.

[0053] In the following examples, coal direct liquefaction oil produced in a megaton-class coal direct liquefaction plant is used as the raw material, and the characteristics of the coal direct liquefaction raw material used are shown in Table 1 below. [Table 1] [Evaluation of the liquefaction performance of recycled hydrogen-donating solvents]

[0054] The liquefaction performance of the recycled hydrogen-donating solvents obtained in the following examples and comparative examples was evaluated by conducting direct coal liquefaction experiments in a high-pressure reactor using the same coal samples. The liquefaction conditions included a reaction temperature of 455°C, an initial hydrogen pressure of 10 MPa, a constant temperature reaction time of 1 hour, a catalyst of Fe2O3 (addition amount of 1% by weight relative to dry coal), a co-catalyst of sulfur (atomic ratio of Fe to S in the catalyst is 2:1), and a mass ratio of coal sample to recycled hydrogen-donating solvent of 45:55. Unless otherwise specified, the above direct coal liquefaction experiments were conducted in accordance with the "High-Pressure Reactor Test Method for Coal Liquefaction Reactivity (GB / T33690-2017)". (Example 1)

[0055] A schematic diagram of the process flow for Example 1 is shown in Figure 1. Using the direct coal liquefaction oil, a recycled hydrogen-donating solvent was prepared according to the following procedure: 1) The directly liquefied coal oil was subjected to the first fractional distillation in the rectification column 1, with the operating temperature at the bottom of the rectification column 1 set to 360°C, the operating temperature at the top set to 160°C, and the operating pressure set to 0.2 MPa. The first fractional distillation yielded liquefied light oil at less than 200°C, liquefied medium oil at 220-320°C, and liquefied heavy oil at over 320°C. 2) The liquefied heavy oil obtained in step 1) was supplied to the suspended bed hydrogenation reactor 2, and the first stage of the hydrogenation reaction was carried out. The catalyst used here was a Ni-Mo hydrogenation purification catalyst (i.e., a commercially available FFT-2 ​​catalyst supplied by the Sinopec Dalian Chemical Research Institute), and the process conditions for the first stage of the hydrogenation reaction included: a reaction temperature of 380°C, a reaction pressure of 15 MPa, and a volume space velocity of 2 h -1 The volume ratio of hydrogen to oil is 1000:1 (Nm³). 3 / m 3 ). 3) The hydrogenation product obtained in step 2) and the liquefied medium oil obtained in step 1) are mixed and supplied to the fixed-bed hydrogenation reactor 3. The catalyst used is a Ni-Mo hydrogenation refining catalyst (i.e., an HTS-358 type catalyst supplied by AXENS, France). The process conditions for the second stage hydrogenation reaction are a reaction temperature of 360°C, a reaction pressure of 15 MPa, and a volume space velocity of 1.5 h. -1 , and the volume ratio of hydrogen to oil is 800:1 (Nm³ 3 / m 3 ) included. Prior to carrying out the hydrogenation reactions in the first and second steps, pre-vulcanization was performed by heating the catalyst from step 2) and the catalyst from step 3), along with virgin kerosene (containing 2% by weight of dimethyl disulfide), to 360°C in a hydrogen atmosphere at a heating rate of 10°C / min to 15°C / min, and holding at that temperature for 12 hours until vulcanization was complete. 4) The hydrogenated oil obtained in step 3) was subjected to a second fractional distillation in the rectification column 4 under the conditions of a rectification column operating pressure of 0.2 MPa, a bottom operating temperature of 310°C, and a top operating temperature of 180°C to obtain hydrogenated light oil at a distillation temperature of less than 220°C, medium-temperature solvent oil at 220-350°C, and high-temperature solvent oil at over 350°C. 5) The high-temperature solvent oil and the medium-temperature solvent oil obtained in step 4) were blended into a recycled hydrogen-donating solvent in a mass ratio of 1:3. (Example 2)

[0056] This embodiment was carried out in reference to Example 1, except that in step 5), the high-temperature solvent oil and the medium-temperature solvent oil were blended into the recycled hydrogen-donating solvent in a mass ratio of 3:1. (Example 3)

[0057] This embodiment was carried out in reference to Example 1, except that in step 5), the high-temperature solvent oil and the medium-temperature solvent oil were blended into the recycled hydrogen-donating solvent in a 1:1 mass ratio. (Example 4)

[0058] This embodiment was carried out in reference to Example 1, except that in step 5), the high-temperature solvent oil and the medium-temperature solvent oil were blended into the recycled hydrogen-donating solvent in a mass ratio of 1:4. (Example 5)

[0059] This embodiment was carried out in reference to Example 1, except that in step 5), the high-temperature solvent oil and the medium-temperature solvent oil were blended into the recycled hydrogen-donating solvent in a mass ratio of 4:1.

[0060] From Examples 1 to 5, it can be seen that in Examples 1 to 4, by controlling the mass ratio of the high-temperature solvent oil to the medium-temperature solvent oil in the range of 3:1 to 1:4, the hydrogen donation index of the recycled hydrogen-donating solvent becomes relatively high, and the coal conversion rate and oil yield in the direct coal liquefaction experiment also become relatively high. By controlling the mass ratio of the high-temperature solvent oil to the medium-temperature solvent oil in the range of 1:1 to 1:3.5, a relatively high hydrogen donation index, coal conversion rate, and oil yield can be achieved without the need to add an excess of the medium-temperature solvent. In Example 1, by controlling the mass ratio of the high-temperature solvent oil to the medium-temperature solvent oil in the range of 1:2.5 to 1:3.5, even better hydrogen donation capacity, coal conversion rate, and oil yield can be achieved simultaneously. (Example 6)

[0061] This embodiment was carried out with reference to Embodiment 1, except as follows. In step 2), the process conditions for the hydrogenation reaction in the first stage are: reaction temperature 400°C, reaction pressure 20 MPa, and volume space velocity 0.5 h. -1 , and the volume ratio of hydrogen to oil is 2000:1 (Nm³ 3 / m 3 ) including; and, In step 3), the process conditions for the hydrogenation reaction in the second stage are: reaction temperature 380°C, reaction pressure 20 MPa, and volume space velocity 0.5 h. -1 , and the volume ratio of hydrogen to oil is 1600:1 (Nm³ 3 / m 3 ) included. (Example 7)

[0062] This embodiment was carried out with reference to Embodiment 1, except as follows. In step 2), the process conditions for the hydrogenation reaction in the first stage are: reaction temperature 350°C, reaction pressure 12 MPa, and volume space velocity 3 h. -1 , and the volume ratio of hydrogen to oil is 400:1 (Nm³). 3 / m 3 ) including; and, In step 3), the process conditions for the hydrogenation reaction in the second stage are: reaction temperature 320°C, reaction pressure 12 MPa, and volume space velocity 3 h. -1 , and the volume ratio of hydrogen to oil is 400:1 (Nm³). 3 / m 3 ) included.

[0063] A comparison of Examples 1, 6, and 7 shows that when Example 1 employs more favorable conditions for the first and second stages of the hydrogenation reaction, not only is the hydrogen consumption in the hydrogenation reaction relatively low, but the hydrogen donation index of the recycled hydrogen-donating solvent is higher compared to Examples 6 and 7, in which the obtained high-temperature solvent oil and medium-temperature solvent oil were blended using the same mass ratio. This allows for the achievement of higher coal conversion rates and oil yields in the direct coal liquefaction experiment. (Comparative Example 1)

[0064] Compared to Example 1, the difference is that step 1) is omitted. Specifically, the coal direct liquefied oil is sent directly to step 2) to carry out the first stage of hydrogenation reaction, then the hydrogenation product is sent to step 3) to carry out the second stage of hydrogenation reaction, then the hydrogenation product obtained in step 3) is sent to step 4) for a second fractional distillation, and the high-temperature solvent oil and medium-temperature solvent oil obtained in step 4) are blended in a mass ratio of 1:3 to form a recyclable hydrogen-donating solvent. Conditions not specified in this Comparative Example 1 were carried out by referring to Example 1.

[0065] Compared to Example 1, Comparative Example 1 shows a significant increase in hydrogen consumption during the hydrogenation reaction. Furthermore, when the high-temperature solvent oil and medium-temperature solvent oil obtained in Comparative Example 1 were blended into the recycled hydrogen-donating solvent in the same mass ratio as in Example 1, the hydrogen donation index of the recycled hydrogen-donating solvent in Comparative Example 1 decreased significantly, resulting in a significant decrease in the coal conversion rate and oil yield in the direct coal liquefaction experiment. (Comparative Example 2)

[0066] Compared to Example 1, the difference is that step 2) is omitted, the liquefied heavy oil obtained in step 1) is mixed with the liquefied medium oil, and the hydrogenation reaction is carried out according to step 3). The other operations are the same as in Example 1.

[0067] In Comparative Example 2, the high-temperature solvent oil and medium-temperature solvent oil obtained in the hydrogenation process were blended with the recycled hydrogen-donating solvent in the same mass ratio as in Example 1. However, the hydrogen-donating index was significantly reduced, and the coal conversion rate and oil yield in the direct coal liquefaction experiment were significantly lowered. (Comparative Example 3)

[0068] Compared to Example 1, this method differs in that the liquefied heavy oil and liquefied medium oil obtained in step 1) were mixed and subjected to a hydrogenation reaction in a suspended-bed hydrogenation reactor according to step 2), while the hydrogenation reaction in a fixed-bed hydrogenation reactor in step 3) was not carried out. The resulting hydrogenated oil underwent a second fractional distillation according to step 4) of Example 1 and was blended with a recycled hydrogen-donating solvent according to step 5) of Example 1. Subsequently, a direct coal liquefaction experiment was conducted referring to Example 1.

[0069] Compared to Example 1, the hydrogen consumption in the hydrogenation reaction during the hydrogenation step of Comparative Example 3 was slightly increased. Furthermore, although the obtained high-temperature solvent oil and medium-temperature solvent oil were blended into the recycled hydrogen-donating solvent in the same mass ratio as in Example 1, the hydrogen donation index of the recycled hydrogen-donating solvent in Comparative Example 3 decreased significantly, resulting in a significant decrease in the coal conversion rate and oil yield in the direct coal liquefaction experiment. (Comparative Example 4)

[0070] Comparative Example 4 was carried out in accordance with Example 1, except that in step 3), only liquefied intermediate oil was sent to the fixed-bed hydrogenation reactor, and in step 4), the hydrogenation product obtained in step 2) was mixed with the hydrogenation product obtained in step 3) and a second fractional distillation was performed.

[0071] Compared to Example 1, although the high-temperature solvent oil and medium-temperature solvent oil obtained in Comparative Example 4 were blended with the recycled hydrogen-donating solvent in the same mass ratio as in Example 1, the hydrogen donation index of the recycled hydrogen-donating solvent in Comparative Example 4 was significantly lower, and the coal conversion rate and oil yield in the direct coal liquefaction experiment were significantly lower. [Table 2]

[0072] In Table 2 above, the hydrogen donating index refers to the mass (mg) of active hydrogen at the β-site of the cycloalkyl group on the cycloalkyl aromatic hydrocarbon per gram of the recycled hydrogen donating solvent. A solvent with a high hydrogen donating index indicates strong hydrogen donating ability and good solvent performance.

[0073] In Table 2 above, density, aromatic carbon ratio, and hydrogen donating index are measurement results for the recycled hydrogen donating solvent; hydrogen consumption in the hydrogenation reaction is the hydrogen consumption in the process of preparing the recycled hydrogen donating solvent by hydrogenating the direct coal liquefaction oil; and coal conversion rate and oil yield are experimental results from the direct coal liquefaction experiment.

[0074] In Table 2 above, the formula for calculating the hydrogen consumption of the hydrogenation reaction is (hydrogen consumption / mass of coal direct liquefaction oil) × 100%; The formula for calculating the coal conversion rate is, ( Response received (Mass of coal / Mass of raw coal) × 100% (anhydrous, ash-free basis), and The formula for calculating oil yield is (mass of produced oil / mass of raw coal) × 100% (on a moisture-free, ash-free basis).

[0075] From the experimental results above, it can be seen that the preparation method according to the present invention can obtain a recycled hydrogen-donating solvent with good hydrogen-donating ability, and that the preparation steps are simple.

[0076] In a preferred embodiment, by employing preferred process conditions for the first and second hydrogenation reactions in the preparation method of the present invention, not only is the hydrogen consumption of the hydrogenation reaction reduced, but the resulting recycled hydrogen-donating solvent has better performance and a superior hydrogen-donating index compared to solvents prepared under other process conditions with the same mass ratio of high-temperature solvent oil to medium-temperature solvent oil. Therefore, a higher coal conversion rate and oil yield can be achieved.

[0077] In a preferred embodiment, the high-temperature solvent oil and the medium-temperature solvent oil obtained by the preparation method according to the present invention are blended with a recycled hydrogen-donating solvent in a mass ratio of 1:1 to 1:3.5, preferably 1:2.5 to 1:3.5, which can result in a product with superior hydrogen-donating ability and contribute to further improving coal conversion rate and oil yield.

[0078] The embodiments described above are given for illustrative purposes only and should not be understood as limiting the invention thereto. Those skilled in the art can make various modifications or variations based on the above description. It is not necessary, nor is it possible, to list all embodiments exhaustively in this specification. Any obvious modifications or variations resulting therefrom remain within the scope of the invention. [Brief explanation of the drawing]

[0079] [Figure 1] Figure 1 is a schematic diagram showing the flow of the preparation process for a recyclable hydrogen-donating solvent according to one embodiment.

Claims

1. A method for preparing a recycled hydrogen-donating solvent for direct coal liquefaction, 1) A step of performing a first fractional distillation on directly liquefied coal oil to obtain liquefied medium-grade oil and liquefied heavy-grade oil, wherein the liquefied medium-grade oil is distillate at 220 to 320°C, and the liquefied heavy-grade oil is distillate at over 320°C; 2) A step of supplying the liquefied heavy oil to the first hydrogenation reactor and carrying out the first stage of the hydrogenation reaction; 3) The liquefied medium-grade oil and the liquefied heavy-grade oil subjected to the first hydrogenation reaction in step 2) are supplied to a second hydrogenation reactor to carry out the second hydrogenation reaction and obtain hydrogenated oil; 4) A second fractional distillation of the hydrogenated oil to obtain a medium-temperature solvent oil and a high-temperature solvent oil, wherein the medium-temperature solvent oil is a distillate at 220 to 350°C, and the high-temperature solvent oil is a distillate at over 350°C; and 5) A step of mixing the medium-temperature solvent oil and the high-temperature solvent oil to prepare the recycled hydrogen donating solvent. A method that includes this.

2. A method for preparing a recycled hydrogen-donating solvent for direct coal liquefaction according to claim 1, wherein in step 2) the first hydrogenation reactor is a suspended bed hydrogenation reactor, and in step 3) the second hydrogenation reactor is a fixed bed hydrogenation reactor.

3. In step 2), the hydrogenation reaction in the first step occurs at a reaction temperature I of 350 to 400°C and a volume space velocity I of 0.5 to 3 hours. －１ , and the volume ratio I of hydrogen to oil is 400 to 2000:1 (Nm³ ３ / m ３ ) to be carried out under the following conditions; In step 3), the hydrogenation reaction in the second stage proceeds with a reaction temperature II of 320 to 380°C and a volume space velocity II of 0.5 to 3 h. －１ , and the volume ratio of hydrogen to oil II is 400 to 1600:1 (Nm³ ３ / m ３ ) shall be carried out under the conditions; and, A method for preparing a recycled hydrogen-donating solvent for direct coal liquefaction according to claim 2, wherein the reaction temperature I is higher than the reaction temperature II, the volume space velocity I is greater than or equal to the volume space velocity II, and the volume ratio I of hydrogen to oil is greater than or equal to the volume ratio II of hydrogen to oil.

4. In step 2), the first hydrogenation reaction is carried out under conditions where the reaction pressure I is 12 to 20 MPa; In step 3), the hydrogenation reaction of the second stage is carried out under conditions where the reaction pressure II is 12 to 20 MPa; and / or, The volume space velocity I is higher than the volume space velocity II, and the volume ratio I of hydrogen to oil is higher than the volume ratio II of hydrogen to oil. A method for preparing a recycled hydrogen-donating solvent for direct coal liquefaction according to claim 3.

5. In step 2), the hydrogenation reaction of the first stage is carried out under the conditions that the reaction temperature I is 360 to 390 °C, the volume space velocity I is 0.8 to 2.5 h －１ , the volume ratio I of hydrogen to oil is 500 to 1200:1 (Nm ３ / m ３ ), and the reaction pressure I is 13 to 19 MPa; In step 3), the hydrogenation reaction of the second stage is carried out at a reaction temperature II of 340 to 370°C and a volume space velocity II of 0.8 to 2 hours. －１ The volume ratio of hydrogen to oil II is 500 to 1200:1 (Nm³). ３ / m ３ ), and the reaction is carried out under conditions where the reaction pressure II is 13 to 19 MPa; and, A method for preparing a recycled hydrogen-donating solvent for direct coal liquefaction according to claim 3, wherein the reaction temperature I is higher than the reaction temperature II, the volume space velocity I is higher than the volume space velocity II, and the volume ratio I of hydrogen to oil is higher than the volume ratio II of hydrogen to oil.

6. The first hydrogenation reaction is carried out in the presence of a first hydrogenation catalyst, and the second hydrogenation reaction is carried out in the presence of a second hydrogenation catalyst. The first hydrogenation catalyst comprises a first support and a first active component; The second hydrogenation catalyst comprises a second support and a second active component; The first active component and the second active component are each independently one or more selected from oxides of group VIB metal elements and oxides of group VIII metal elements. A method for preparing a recycled hydrogen-donating solvent for direct coal liquefaction according to claim 1.

7. The group VIB metallic element is selected from Mo and / or W, and the group VIII metallic element is selected from Co and / or Ni; and, The method for preparing a recycled hydrogen-donating solvent for direct coal liquefaction according to claim 6, wherein the first carrier and the second carrier are each independently one or more selected from alumina, Y-type molecular sieves, and β-type molecular sieves.

8. In the first hydrogenation catalyst, the first support is contained in an amount of 60 to 90% by weight, and the first active component is contained in an amount of 10 to 40% by weight; and A method for preparing a recycled hydrogen-donating solvent for direct coal liquefaction according to claim 6, wherein the second hydrogenation catalyst contains the second support in an amount of 60 to 90% by weight, and the second active component in an amount of 10 to 40% by weight.

9. The first active component and the second active component are, independently, a combination of an oxide of a group VIB metal element and an oxide of a group VIII metal element. A method for preparing a recycled hydrogen-donating solvent for direct coal liquefaction according to claim 8.

10. In the first hydrogenation catalyst, the oxide of the group VIB metal element is contained in an amount of 10 to 35% by weight, and the oxide of the group VIII metal element is contained in an amount of 4 to 10% by weight; and / or, In the second hydrogenation catalyst, the oxide of the group VIB metal element is contained in an amount of 10 to 30% by weight, and the oxide of the group VIII metal element is contained in an amount of 1 to 6% by weight. A method for preparing a recycled hydrogen-donating solvent for direct coal liquefaction according to claim 9.

11. The method for preparing a recycled hydrogen-donating solvent for direct coal liquefaction according to claim 1, wherein in step 5), the mass ratio of the medium-temperature solvent oil to the high-temperature solvent oil is 4:1 to 1:

3.

12. The method for preparing a recycled hydrogen-donating solvent for direct coal liquefaction according to claim 11, wherein in step 5), the mass ratio of the medium-temperature solvent oil to the high-temperature solvent oil is 1:1 to 3.5:

1.

13. The method for preparing a recycled hydrogen-donating solvent for direct coal liquefaction according to claim 11, wherein in step 5), the mass ratio of the medium-temperature solvent oil to the high-temperature solvent oil is 2.5:1 to 3.5:1.

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