Preparation method of high-purity hexadecahydropyrene

Abstract

The invention discloses a preparation method of high-purity hexadecahydropyrene, which comprises the following steps: (1) carrying out hydrofining reaction on direct coal liquefaction oil and hydrogen to obtain hydrofined oil; (2) carrying out hydrogenation mild cracking reaction on the hydrofined oil obtained in the step (1) to convert polycycloalkane and / or polycyclic aromatic hydrocarbon with side chains in the hydrofined oil into polycycloalkane and / or polycyclic aromatic hydrocarbon with broken side chains, so as to obtain hydrogenation mild cracking effluent; (3) carrying out further hydrofining reaction on the hydrogenation mild cracking effluent obtained in the step (2) to obtain hydrofinishing effluent; (4) feeding hydrofinishing effluent obtained in the step (3) into a rectification unit, and separating to obtain fraction at 280-320 DEG C as hexadecahydropyrene-rich oil; and (5) feeding the hexadecahydropyrene-rich oil obtained in the step (4) and the extraction solvent into a recrystallization tower for extraction crystallization, and filtering to remove a mixture of the extraction solvent and oil in the hexadecahydropyrene-rich oil to obtain high-purity hexadecahydropyrene.

Description

Technical Field

[0001] The present invention belongs to the field of coal chemical industry and relates to a method for preparing high-purity hexadecahydropyrene. Specifically, high-purity hexadecahydropyrene is prepared using coal direct liquefaction oil as a raw material and is used in the fields of chemical industry, medicine, material synthesis, etc., thereby extending the coal direct liquefaction product chain and improving the economic benefits of coal direct liquefaction. Background Art

[0002] Pyrene is an important component in coal tar, but coal tar raw materials basically do not contain hexahydropyrene. Direct extraction costs are high, and the extracted hexahydropyrene has low purity and low yield, which is economically unfeasible. At present, hexahydropyrene is mainly obtained by pyrene synthesis, which is limited by parallel sequential reactions, has low purity, harsh purification process, and the production process is monopolized by foreign countries.

[0003] CN108130128A discloses a process for preparing hexahydropyrene using coal tar as raw material. After pretreatment, the coal tar is subjected to hydrorefining and hydrocracking reactions, and the resulting liquid is fractionated; the diesel fraction enters the supplementary refining reaction zone for hydrogenation saturation reaction; the hydrogenated product is cut, cooled, and filtered to obtain high-purity hexahydropyrene. This invention realizes the extraction of high-purity hexahydropyrene from coal tar. This invention uses high-temperature coal tar as raw material, the raw material properties are poor, the hydrogenation process conditions are harsh, and the product yield is low, and the purity needs to be further improved.

[0004] CN108164384A discloses a method for preparing hexahydropyrene by hydrogenating a hydrocarbon oil raw material of a pyrene-based compound. The invention prepares a high-purity hexahydropyrene product by subjecting a pyrene-based compound (selected from at least one of pyrene and its unsaturated hydrogenation products) to a noble metal hydrogenation reaction. The invention is suitable for raw materials with relatively clean raw oil and pyrene-based compounds in the composition, and cannot process raw materials with complex composition and relatively poor properties.

[0005] The direct coal liquefaction process is to prepare coal powder, solvent oil, catalyst, etc. into a coal slurry of a certain concentration and then mix it with hydrogen, and then enter the coal slurry preheater and coal liquefaction reactor to react under certain conditions (reaction temperature 400-480℃, reaction pressure 10-30MPa), and separate the reaction products in the separation system to obtain gas products, liquefied oil products, and solid residues. Studies have found that direct coal liquefaction oil is rich in pyrene and pyrene compounds, so it can provide a stable and reliable source for the production of hexahydropyrene. If high-purity hexahydropyrene can be prepared using direct coal liquefaction oil as raw material, it can not only extend the direct coal liquefaction product chain, but also further improve the economic benefits of direct coal liquefaction. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing high-purity hexadecahydropyrene, using coal direct liquefaction oil as raw material to prepare high-purity hexadecahydropyrene, thereby extending the coal direct liquefaction product chain and improving the economic benefits of coal direct liquefaction.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing high-purity hexahydropyrene comprises the following steps:

[0009] (1) direct coal liquefaction oil and hydrogen enter a hydrotreating unit, contact with a hydrotreating catalyst in the presence of hydrogen, perform a hydrotreating reaction, and obtain hydrotreating oil;

[0010] (2) the hydrotreated oil obtained in step (1) enters a hydro-mild cracking unit, contacts a hydro-mild cracking catalyst in the presence of hydrogen, and performs a hydro-mild cracking reaction to convert polycyclic alkanes and / or polycyclic aromatic hydrocarbons with side chains in the hydro-treated oil into polycyclic alkanes and / or polycyclic aromatic hydrocarbons with broken side chains, thereby obtaining a hydro-mild cracking effluent;

[0011] (3) The hydro-mild cracking effluent obtained in step (2) enters a hydro-refining unit, and the hydro-refining uses a precious metal hydro-refining catalyst in the presence of hydrogen to carry out a further hydro-refining reaction to obtain a hydro-refining effluent;

[0012] (4) The hydroprocessing refining effluent obtained in step (3) enters a distillation unit, and a fraction falling into the temperature range of 280° C. to 320° C. is separated to obtain hexadecene-rich pyrene oil;

[0013] (5) The hexahydropyrene-rich oil and the extraction solvent obtained in step (4) enter a recrystallization tower for extraction and crystallization, and high-purity hexahydropyrene is obtained after filtering to remove the mixture of the extraction solvent and the oil in the hexahydropyrene-rich oil.

[0014] In step (1) of the present invention, the coal direct liquefaction oil and hydrogen are subjected to a hydrotreating reaction in the presence of a hydrotreating catalyst to remove heteroatoms (such as sulfur, nitrogen, etc.) in the oil product and to saturate the aromatic hydrocarbons. It is understood in the art that the hydrotreating treatment of the coal direct liquefaction oil is well known in the art, for example, a hydrotreating catalyst is loaded in a hydrotreating unit to carry out a hydrotreating reaction.

[0015] In the present invention, the hydrotreating catalyst used may be a hydrotreating catalyst commonly used in the art. In some embodiments, the hydrotreating catalyst includes a carrier and a supported active component. The content of the active component may be 10-40 wt.% in terms of oxide, and the content of the carrier may be 50-80 wt.%.

[0016] The carrier of the hydrorefining catalyst can generally be alumina or amorphous silicon aluminum, and the active component can generally be a metal of Group VIB and a metal of Group VIII; wherein the metal of Group VIB is Mo and / or W, and its content is 15-30wt.% in terms of oxide; the metal of Group VIII is Co and / or Ni, and its content is 2-6wt.% in terms of oxide; preferably, it is a Ni-Mo binary or Ni-Mo-W ternary active metal system. It is understood in the art that the above hydrorefining catalyst can be a commercial catalyst, and of course, it can also be a catalyst prepared by itself according to the prior art with the above characteristics, such as the RNC-2 hydrorefining catalyst developed and produced by the Petrochemical Research Institute.

[0017] In some embodiments, the hydrofining reaction conditions are: reaction pressure 3-21 MPa, reaction temperature 330-420°C, hydrogen oil volume ratio 400-2000:1 (Nm 3 / m 3 ), volume space velocity 0.1-2.5h -1 Preferably, the hydrofining reaction conditions are: reaction pressure 10-15MPa, reaction temperature 350-400°C, hydrogen-oil volume ratio 800-1200:1, volume space velocity 0.5-1h -1 .

[0018] In a preferred embodiment, the active component in the hydrotreating catalyst catalyzes the hydrotreating reaction in a sulfided state.

[0019] In some embodiments, in the hydrotreating catalyst, the specific surface area of ​​the hydrotreating catalyst is ≮150m2 / g, the pore volume is ≮0.24ml / g, and the pore diameter is ≮4nm; preferably, the specific surface area of ​​the hydrotreating catalyst is 150-300m2 / g, the pore volume is 0.3-0.5ml / g, and the pore diameter is ≮5nm; wherein, “≮” means “not less than”.

[0020] In step (2) of the present invention, the hydrorefined oil is subjected to mild hydrogenation and mild cracking treatment, the purpose of which is to perform mild hydrogenation and mild cracking, so as to break the side chains of polycyclic alkanes and / or aromatics while retaining the polycyclic aromatic hydrocarbons and polycyclic alkanes of the oil product, thereby regulating the composition structure of the oil product. It is understood in the art that any mild hydrogenation and mild cracking catalyst and mild hydrogenation and mild cracking reaction conditions that can achieve the above purpose can be applied to the method provided by the present invention.

[0021] In a preferred embodiment, in order to achieve a better hydrocracking effect, the carrier of the hydrocracking catalyst can be a high-silicon zeolite molecular sieve or a composite molecular sieve of a high-silicon zeolite molecular sieve and a Y-type molecular sieve, and the active component is a combination of a VIB group metal and a VIII group metal, wherein the VIB group metal is Mo and / or W, and its content is 10-30wt.% in terms of oxide; the VIII group metal is Co and / or Ni, and its content is 4-10wt.% in terms of oxide; wherein the carrier of the hydrocracking catalyst contains 50-90wt.% silicon oxide, preferably 60-80wt.%, and 5-30wt.% aluminum oxide, preferably 5-15wt.%;

[0022] In some embodiments, the reaction conditions of the hydrocracking reaction are: reaction pressure 3-21 MPa, reaction temperature 250-380°C, hydrogen to oil volume ratio 400-2000:1, volume space velocity 0.1-5h -1 Preferably, the conditions of the mild hydrogenation cracking reaction are: reaction pressure 10-15MPa, reaction temperature 280-360°C, hydrogen-oil volume ratio 800-1200:1, volume space velocity 0.8-3h -1 ; Wherein, the hydrogen-to-oil volume ratio is the volume ratio of hydrogen to the hydrocracking effluent.

[0023] In some embodiments, the high-silicon zeolite molecular sieve uses ethyl orthosilicate and aluminum sulfate as raw materials, respectively as silicon and aluminum sources; 1,6-hexanediamine (DAH) is used as a template, and potassium hydroxide is added to improve the crystallinity of the synthesized molecular sieve, the molar ratio of SiO2 and OH- added is 2-15:1, the amount of template added is controlled at a molar ratio of SiO2 and DAH of 1-10:1, and the high-silicon zeolite molecular sieve is synthesized by hydrothermal synthesis; during the synthesis process, the crystallization temperature is 130-190°C, and the crystallization time is 20-60h. Preferably, the high-silicon molecular sieve is a ZSM-22 molecular sieve, which has a topological structure with the same TON structure, and an elliptical straight channel is composed of ten-membered rings.

[0024] In some embodiments, the composite molecular sieve is obtained by bonding, molding and calcining the high silicon zeolite molecular sieve and the Y-type molecular sieve under the action of a binder to obtain the composite molecular sieve as a carrier, which is well known in the art. Preferably, the specific surface area of ​​the composite molecular sieve is 200-500m2 / g, the pore volume is 0.5-2.0mL / g, and the infrared acidity is 0.40-1.2mmol / g; more preferably, the molar ratio of SiO2 and Al2O3 in the composite molecular sieve is 10-40:1, the infrared acidity is 0.2-0.9mmol / g, the specific surface area is 300-450m2 / g, and the pore volume is 0.2-0.65mL / g.

[0025] In step (3) of the present invention, the hydrocracking effluent is subjected to hydrofining for the purpose of further hydrogenating and saturating the olefins and / or aromatics therein, which is well known in the art. It is understood in the art that the hydrofining catalysts and reaction conditions commonly used in the art that can achieve the above purpose can be applied to the method provided by the present invention.

[0026] In some embodiments, the hydrorefining catalyst uses a precious metal hydrorefining catalyst, and its active component is one or both of Pt and Pd; preferably, in the hydrorefining catalyst, the Pd content is 0.1-0.8wt.% in terms of metal element, and the Pt content is 0.1-0.5wt.% in terms of metal element. In some embodiments, the hydrorefining catalyst may also include an additive, and the additive may be at least one of Si, Mg and Ti, preferably an oxide of Mg. It is understood in the art that the above-mentioned hydrorefining catalyst may be a commercial catalyst, and of course it may also be a catalyst prepared by itself according to the prior art with the above-mentioned characteristics, such as the RLF-2 hydroprocessing catalyst developed and produced by the Petrochemical Research Institute.

[0027] In some embodiments, the reaction conditions of the hydrofining reaction are: reaction pressure 3-15MPa, reaction temperature 140-300°C, hydrogen-to-oil volume ratio 200-2000:1, and volume space velocity 0.1-2.5h-1; preferably, the conditions of the hydrofining reaction are: reaction pressure 6-15MPa; reaction temperature 160-220°C; hydrogen-to-oil volume ratio 400-1000:1; volume space velocity 0.6-1.5h-1; wherein the hydrogen-to-oil volume ratio is the volume ratio of hydrogen to the hydrofining effluent.

[0028] In some embodiments, the specific surface area of ​​the hydrorefining catalyst is ≮200m2 / g, the pore volume is ≮0.3mL / g, the pore diameter is ≮4nm, and the active metal H2 adsorption capacity is ≮80mL / g; preferably, the specific surface area of ​​the hydrorefining catalyst is 200-400m2 / g, the pore volume is 0.3-0.6mL / g, the pore diameter is 5-15nm, and the active metal H2 adsorption capacity is 90-150mL / g.

[0029] In step (4) of the present invention, the hydroprocessing refining effluent is subjected to distillation separation, and the fraction falling into the range of 280°C to 320°C is used as hexahydropyrene-rich oil; in addition, it can be understood in the art that the fraction <280°C is used as the hydrogenated light oil fraction, as the naphtha and diesel fractions, and the fraction >320°C is used as the hydrogenated heavy oil fraction, as the lubricating oil fraction.

[0030] In step (5) of the present invention, the obtained hexahydropyrene-rich oil is subjected to extraction and crystallization using an extraction solvent so that the oil in the hexahydropyrene-rich oil is dissolved in the extraction solvent, thereby selectively crystallizing hexahydropyrene, and then the mixture of the extraction solvent and the oil in the hexahydropyrene-rich oil can be removed by filtration to obtain high-purity hexahydropyrene.

[0031] In a preferred embodiment, the extraction solvent is a mixture of one or more of toluene, n-heptane and MTBE.

[0032] In a preferred embodiment, the volume ratio of the extraction solvent to the hexahydropyrene-rich oil is (2-4):1, the extraction temperature is 30-150°C, and the extraction pressure is 0.1-0.8MPa.

[0033] In some embodiments, the method of the present invention may further include step (6): flash separation of the mixture obtained in step (5), and recycling the separated extraction solvent. For example, the obtained mixture is sent to a flash tower for separation, with an operating pressure of 0.01-0.05 MPa and an operating temperature of 30-150° C., the extraction solvent obtained at the top is recycled back to the recrystallization tower, and the product oil at the bottom is used as the product out-of-bounds zone.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] (1) Providing a stable and reliable source for the production of hexadecahydropyrene. The raw materials for the traditional production of hexadecahydropyrene mainly come from coal tar or the hydrogenation synthesis of pyrene, and pyrene also mainly comes from coal tar extraction. Different coal tars have different compositions, and the content of pyrene in them also varies, which cannot provide a stable and reliable source for the production of hexadecahydropyrene. However, using coal direct liquefaction oil as raw material, the composition and properties of this oil are relatively stable, and the primary products of coal direct liquefaction are rich in pyrene and pyrene compounds. Therefore, it can provide a stable and reliable source for the production of hexadecahydropyrene.

[0036] (2) The present invention can produce hexahydropyrene with a high yield. Due to the production process, the content of pyrene and pyrene compounds in the raw material composition of traditional coal tar is relatively low, and the yield of hexahydropyrene produced through the processing process is also low. The content of pyrene and pyrene compounds in direct coal liquefaction oil is relatively high. Through the present invention, the pyrene and pyrene compounds in the raw materials can be better converted into hexahydropyrene, and the hexahydropyrene component can be retained without further conversion, thereby obtaining a high yield of hexahydropyrene.

[0037] (3) The hexadecahydropyrene prepared by the present invention has high purity. The present invention further purifies and separates the hydrogenated coal direct liquefaction oil, and can separate hexadecahydropyrene from the oil phase as much as possible, breaking through the bottleneck of separating hexadecahydropyrene from other hydrocarbon components, and obtaining high-purity hexadecahydropyrene monomer hydrocarbon.

[0038] (4) The present invention can obtain high-purity hexahydropyrene and, because it can remove crystals in the oil product and change the composition of the oil product, the performance of the oil is improved, and fuel oil and lubricating oil fractions with excellent performance are obtained.

[0039] (5) The hydrogenation conditions of the coal direct liquefaction oil of the present invention are relatively mild. Because the raw material oil used in the present invention is the coal direct liquefaction oil product oil, which has been through the coal direct liquefaction process, the impurity content contained therein is relatively low, the cycloalkane content is relatively high, and the side chain on the cycloalkane is relatively short. In order to obtain crude hexahydropyrene with higher purity in the hydrogenation stage, the required hydrogenation conditions are relatively mild compared to the work using coal tar as raw material.

[0040] (6) The mild hydrogenation cracking catalyst used in the present invention can break the side chains on the ring as much as possible without affecting the ring opening of cycloalkanes and aromatics, thereby increasing the yield of hexahydropyrene. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A schematic diagram of a process flow for implementing the method of the present invention. DETAILED DESCRIPTION

[0042] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0043] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values, such as values ​​of ±10% of the endpoint values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article. In the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other.

[0044] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so as to describe the embodiments of the present invention described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0045] like Figure 1 As shown, in the process of preparing high-purity hexahydropyrene from coal direct liquefied oil, hydrogen 1 and coal direct liquefied oil 2 enter the hydroprocessing unit 3 for hydroprocessing to remove heteroatoms such as sulfur and nitrogen in the oil product and saturate the aromatic part. The hydrorefined oil 4 enters the hydrocracking unit 5 to convert the polycyclic alkanes and / or polycyclic aromatic hydrocarbons with side chains in the hydrorefined oil into polycyclic alkanes and / or polycyclic aromatic hydrocarbons with broken side chains, that is, to break the side chains on the polycyclic aromatic hydrocarbons and polycyclic alkanes, while retaining the main structure of the polycyclic aromatic hydrocarbons and polycyclic alkanes. The hydrocracking effluent 6 enters the hydrorefining supplementary refining unit 7 for hydrogenation and saturation of olefins and aromatic hydrocarbons, and the hydrorefining supplementary refining effluent 8 enters the distillation unit 9 to separate the hydrogenated light oil fraction 10, the hexahydropyrene-rich oil fraction 11, and the hydrogenated heavy oil fraction 12. The hexadecahydropyrene oil fraction 11 and the extraction solvent 14 enter the recrystallization tower 13 to separate high-purity hexadecahydropyrene 15, and the mixture 16 enters the extraction solvent recovery tower 17. The recovered extraction solvent 18 is circulated back to the recrystallization tower 13, and the product oil 19 is out of the boundary area.

[0046] The present invention is further described below in conjunction with the examples / comparative examples, wherein the catalysts used are as follows:

[0047] The hydrorefining catalyst is the RNC-2 hydrorefining catalyst developed and produced by the Petrochemical Research Institute (sulfurized before use);

[0048] The hydroprocessing catalyst used for supplementary refining is the RLF-2 hydroprocessing catalyst developed and produced by the Petrochemical Research Institute;

[0049] The hydrocracking catalyst is a composite molecular sieve obtained by impregnating active components, drying and calcining; wherein the composite molecular sieve is obtained by bonding, molding and calcining a ZSM-22 molecular sieve (silicon-aluminum ratio of 60) and a Y-type molecular sieve (silicon-aluminum ratio of 8) under the action of a binder alumina;

[0050] The hydrocracking catalyst composition is as follows:

[0051] Catalyst properties Cat-1 Cat-2 ZSM-22, wt% 30 35 Y, wt% 30 25 NiO, wt% 6 8 <![CDATA[MoO 3 ,wt%]]> 15 10 <![CDATA[WO 3 ,wt%]]> 10 6 Alumina, wt% 20 20

[0052] Example 1

[0053] like Figure 1 As shown, coal direct liquefaction oil (properties are shown in Table 1 below, the same below) is subjected to hydrorefining-hydrocracking-hydrorefining-primary distillation-recrystallization-extraction solvent recovery to prepare high-purity hexahydropyrene, specifically:

[0054] (1) Direct coal liquefaction oil and hydrogen enter a hydrotreating unit, and in the presence of hydrogen, contact with a hydrotreating catalyst to perform a hydrotreating reaction; the reaction conditions of the hydrotreating reaction are: reaction pressure 15 MPa, reaction temperature 380°C, hydrogen-oil volume ratio 1000:1, volume space velocity 2 h -1 ;

[0055] (2) The hydrorefined oil obtained in step (1) enters a hydrocracking unit, which uses a hydrocracking catalyst (Cat-1) containing a high-silicon zeolite molecular sieve as a carrier to carry out a hydrocracking reaction in the presence of hydrogen. The conditions of the hydrocracking reaction are: reaction pressure 15 MPa, reaction temperature 360°C, hydrogen-to-oil volume ratio 800:1, and volume space velocity 1.5 h -1 ; Wherein, the hydrogen-to-oil volume ratio is the volume ratio of hydrogen to the hydrocracking effluent;

[0056] (3) The hydro-mild cracking effluent obtained in step (2) enters a hydro-refining unit, and the hydro-refining uses a precious metal hydro-refining catalyst in the presence of hydrogen to carry out further hydro-refining reaction; the reaction conditions of the hydro-refining reaction zone are: reaction pressure 15 MPa; reaction temperature 220°C; hydrogen-oil volume ratio 500:1; volume space velocity 1h -1 ; wherein the hydrogen-to-oil volume ratio is the volume ratio of hydrogen to the hydrogenation supplementary refining effluent;

[0057] (4) The hydroprocessing refining effluent obtained in step (3) enters a distillation unit to separate and obtain a fraction of 280°C to 320°C as hexahydropyrene-rich oil; the fraction of less than 280°C is used as a hydrogenated light oil fraction, as a naphtha and diesel fraction; the fraction of more than 320°C is used as a hydrogenated heavy oil fraction, as a lubricating oil fraction;

[0058] (5) The hexahydropyrene-rich oil and the extraction solvent obtained in step (4) enter a recrystallization tower, the ratio of the solvent to the hexahydropyrene-rich oil is 3:1, the extraction solvent is MTBE, the operating temperature is 40° C., the operating pressure is 0.2 MPa, and high-purity hexahydropyrene is obtained after filtration at the bottom (the results are shown in Table 2); the extraction solvent and oil mixture enter an extraction solvent recovery tower.

[0059] (6) The solvent and oil mixture obtained in step (5) are separated in an extraction solvent recovery tower at an operating pressure of 0.02 MPa and an operating temperature of 120° C. The top extraction solvent is recycled back to the recrystallization tower, and the product oil is used as the product out-of-bounds zone.

[0060] Example 2

[0061] like Figure 1 As shown, the coal direct liquefaction oil is subjected to hydrofining-hydrocracking-hydrofining supplementary refining-primary distillation-recrystallization-extraction solvent recovery to prepare high-purity hexahydropyrene, specifically:

[0062] (1) Direct coal liquefaction oil and hydrogen enter a hydrotreating unit, and in the presence of hydrogen, contact with a hydrotreating catalyst to perform a hydrotreating reaction; the reaction conditions of the hydrotreating reaction are: reaction pressure 12 MPa, reaction temperature 360°C, hydrogen-oil volume ratio 1200:1, volume space velocity 1 h -1 ;

[0063] (2) The hydrorefined oil obtained in step (1) enters a hydrocracking unit, which uses a hydrocracking catalyst (Cat-2) containing a high-silicon zeolite molecular sieve as a carrier to carry out a hydrocracking reaction in the presence of hydrogen. The conditions for the hydrocracking reaction are: a reaction pressure of 12 MPa, a reaction temperature of 340° C., a hydrogen-to-oil volume ratio of 1000:1, and a volume space velocity of 1 h -1 ; Wherein, the hydrogen-to-oil volume ratio is the volume ratio of hydrogen to the hydrocracking effluent;

[0064] (3) The hydro-mild cracking effluent obtained in step (2) enters a hydro-refining unit, and the hydro-refining uses a precious metal hydro-refining catalyst in the presence of hydrogen to carry out further hydro-refining reaction; the reaction conditions of the hydro-refining reaction zone are: reaction pressure 12 MPa; reaction temperature 200° C.; hydrogen-to-oil volume ratio 800:1; volume space velocity 0.8 h -1 ; wherein the hydrogen-to-oil volume ratio is the volume ratio of hydrogen to the hydrogenation supplementary refining effluent;

[0065] (4) The hydroprocessing refining effluent obtained in step (3) enters a distillation unit to separate and obtain a fraction of 280°C to 320°C as hexahydropyrene-rich oil; the fraction of less than 280°C is used as a hydrogenated light oil fraction, as a naphtha and diesel fraction; the fraction of more than 320°C is used as a hydrogenated heavy oil fraction, as a lubricating oil fraction;

[0066] (5) The hexahydropyrene-rich oil obtained in step (4) and the extraction solvent enter a recrystallization tower, the ratio of the solvent to the hexahydropyrene-rich oil is 3:1, the extraction solvent is toluene, the operating temperature is 30-150° C., and the operating pressure is 0.1-0.8 MPa (toluene solvent, operating temperature 80° C., operating pressure 0.2 MPa), and the bottom is filtered to obtain high-purity hexahydropyrene; the extraction solvent and oil mixture enter an extraction solvent recovery tower.

[0067] (6) The solvent and oil mixture obtained in step (5) are separated in an extraction solvent recovery tower at an operating pressure of 0.01-0.05 MPa and an operating temperature of 30-150° C. The top extraction solvent is recycled back to the recrystallization tower, and the product oil is used as the product out-of-bounds zone.

[0068] Example 3

[0069] The difference from Example 1 is that in step (5), the ratio of the extraction solvent to the hexahydropyrene-rich oil is 3:1, the extraction solvent is n-heptane, the operating temperature is 30-150° C., and the operating pressure is 0.1-0.8 MPa (n-heptane solvent, operating temperature is 60° C., and operating pressure is 0.2 MPa).

[0070] Comparative Example 1

[0071] Compared with Example 1, the hydrocracking unit is missing, but the others are the same.

[0072] Comparative Example 2

[0073] Compared with Example 1, the supplementary refining unit is missing, and the others are the same.

[0074] Comparative Example 3

[0075] Compared with Example 1, the recrystallization unit is missing, and the others are the same.

[0076] Table 1 Properties of direct coal liquefaction feedstock oil

[0077]

[0078]

[0079] Table 2 Implementation results of examples and comparative examples

[0080] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Yield of hexahydropyrene, wt% 12.5 12.3 12.1 8.4 6.5 10.1 Hexahydropyrene purity, wt% 99.6 99.5 99.8 98.2 98.1 78.7 Density (20℃), kg / m3 962 960 965 959 958 940 Flash point, °C 125.4 125.4 125.4 125.1 125.0 121.3

[0081] It can be seen from the above embodiments / comparative examples that by adopting the process of the present invention, the yield and purity of hexahydropyrene are significantly improved, and the product quality is high.

Claims

1. A method for preparing high-purity hexahydropyrene, comprising the following steps: (1) direct coal liquefaction oil and hydrogen enter a hydrotreating unit, contact with a hydrotreating catalyst in the presence of hydrogen, perform a hydrotreating reaction, and obtain hydrotreating oil; (2) the hydrotreated oil obtained in step (1) enters a hydro-mild cracking unit, contacts a hydro-mild cracking catalyst in the presence of hydrogen, and performs a hydro-mild cracking reaction to convert polycyclic alkanes and / or polycyclic aromatic hydrocarbons with side chains in the hydro-treated oil into polycyclic alkanes and / or polycyclic aromatic hydrocarbons with broken side chains, thereby obtaining a hydro-mild cracking effluent; (3) The hydro-mild cracking effluent obtained in step (2) enters a hydro-refining unit, and the hydro-refining uses a precious metal hydro-refining catalyst in the presence of hydrogen to carry out a further hydro-refining reaction to obtain a hydro-refining effluent; (4) The hydroprocessing refining effluent obtained in step (3) enters a distillation unit, and a fraction falling into the temperature range of 280° C. to 320° C. is separated to obtain hexadecene-rich pyrene oil; (5) The hexahydropyrene-rich oil and the extraction solvent obtained in step (4) enter a recrystallization tower for extraction and crystallization, and high-purity hexahydropyrene is obtained after filtering to remove the mixture of the extraction solvent and the oil in the hexahydropyrene-rich oil.

2. The preparation method according to claim 1, characterized in that: In step (1), the carrier of the hydrotreating catalyst is alumina, and the active component is a combination of a VIB group metal and a VIII group metal; the VIB group metal is Mo and / or W, and its content is 15-30wt.% in terms of oxide; the VIII group metal is Co and / or Ni, and its content is 2-6wt.% in terms of oxide; Preferably, the hydrofining reaction conditions are: reaction pressure 3-21 MPa, reaction temperature 330-420°C, hydrogen-oil volume ratio 400-2000:1, volume space velocity 0.1-2.5h -1 Preferably, the hydrofining reaction conditions are: reaction pressure 10-15MPa, reaction temperature 350-400°C, hydrogen-oil volume ratio 800-1200:1, volume space velocity 0.5-1h -1 .

3. The preparation method according to claim 1, characterized in that: In step (2), the carrier of the hydrocracking catalyst is a high-silicon zeolite molecular sieve or a composite molecular sieve of a high-silicon zeolite molecular sieve and a Y-type molecular sieve, and the active component is a combination of a VIB group metal and a VIII group metal, wherein the VIB group metal is Mo and / or W, and the content thereof is 10-30 wt.% in terms of oxide; the VIII group metal is Co and / or Ni, and the content thereof is 4-10 wt.% in terms of oxide; wherein the carrier of the hydrocracking catalyst contains 60-80 wt.% of silicon oxide, preferably 60-80 wt.%, and 5-30 wt.% of aluminum oxide, preferably 5-15 wt.%; Preferably, the reaction conditions of the mild hydrogenation cracking reaction are: reaction pressure 3-21 MPa, reaction temperature 250-380°C, hydrogen-oil volume ratio 400-2000:1, volume space velocity 0.1-5h -1 More preferably, the conditions of the mild hydrogenation cracking reaction include: reaction pressure 10-15MPa, reaction temperature 280-360°C, hydrogen-oil volume ratio 800-1200:1, volume space velocity 0.8-3h -1 ; Wherein, the hydrogen-to-oil volume ratio is the volume ratio of hydrogen to the hydrocracking effluent.

4. The preparation method according to claim 3, characterized in that: The high-silicon zeolite molecular sieve uses ethyl orthosilicate and aluminum sulfate as raw materials, which are respectively used as silicon and aluminum sources; 1,6-hexanediamine (DAH) is used as a template agent, and potassium hydroxide is added to improve the crystallinity of the synthesized molecular sieve, the molar ratio of added SiO2 and OH- is 2-15:1, and the amount of the template agent added is controlled at a molar ratio of SiO2 and DAH of 1-10:

1. The high-silicon zeolite molecular sieve is synthesized by a hydrothermal synthesis method; during the synthesis process, the crystallization temperature is 130-190°C and the crystallization time is 20-60h.

5. The preparation method according to claim 3 or 4, characterized in that: The composite molecular sieve is obtained by bonding the high-silicon zeolite molecular sieve and the Y-type molecular sieve with a binder, forming and calcining the composite molecular sieve as a carrier.

6. The preparation method according to any one of claims 1 to 5, characterized in that: In step (3), the hydrogenation refining adopts a precious metal hydrogenation refining catalyst, and its active component is one or both of Pt and Pd; preferably, the Pd content in the hydrogenation refining catalyst is 0.1-0.8wt.% calculated as metal element, and the Pt content is 0.1-0.5wt.% calculated as metal element; Preferably, the reaction conditions of the hydrofining reaction are: reaction pressure 3-15MPa, reaction temperature 140-300°C, hydrogen-to-oil volume ratio 200-2000:1, and volume space velocity 0.1-2.5h-1; more preferably, the conditions of the hydrofining reaction are: reaction pressure 6-15MPa; reaction temperature 160-220°C; hydrogen-to-oil volume ratio 400-1000:1; volume space velocity 0.6-1.5h-1; wherein the hydrogen-to-oil volume ratio is the volume ratio of hydrogen to the hydrofining effluent.

7. The preparation method according to any one of claims 1 to 6, characterized in that In step (4), the separated fraction with a temperature of less than 280° C. is used as naphtha and diesel fractions, and the fraction with a temperature of more than 320° C. is used as lubricating oil fraction.

8. The preparation method according to any one of claims 1 to 7, characterized in that: In step (5), the extraction solvent is a mixture of one or more of toluene, n-heptane and MTBE.

9. The preparation method according to claim 8, characterized in that: The volume ratio of the extraction solvent to the hexahydropyrene-rich oil is (2-4):1, the extraction temperature is 30-150°C, and the extraction pressure is 0.1-0.8MPa.

10. The preparation method according to any one of claims 1 to 9, characterized in that: The method further comprises step (6): flash distilling and separating the mixture obtained in step (5), and recycling the separated extraction solvent.

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