A method for hydrocracking of coal synthetic oil

Abstract

The present invention discloses a hydrocracking method for coal synthetic oil. The coal synthetic oil first undergoes a hydrorefining reaction, and the hydrorefining effluent contacts a hydrocracking catalyst containing ZSM-5@β composite molecular sieve and undergoes isomerization and cracking reactions; the hydrocracking reaction effluent is fractionated to obtain liquid products including naphtha and tail oil components; the obtained naphtha passes through a normal and isomer adsorption separation device to obtain components rich in normal paraffins and components rich in isoparaffins. The present invention is applicable to the hydrocracking of coal synthetic oil to produce high-octane gasoline and low-freezing diesel components, can significantly increase the isoparaffin content and octane number in the gasoline components, and achieve the purpose of reducing the diesel-gasoline ratio.

Description

Technical Field

[0001] The present invention relates to a hydrocracking method for coal synthetic oil, which is particularly suitable for the process of producing gasoline and low-freezing diesel by hydrocracking coal synthetic oil, and can achieve the purpose of converting coal synthetic oil into high-value-added products. Background Art

[0002] Conventional traditional coal synthetic oil mainly produces diesel, while the gasoline yield is very low. This is mainly because the paraffin content in the feedstock oil produced by indirect coal liquefaction is high. After hydroconversion, it is still mainly paraffin, and the octane number is less than 85, so it cannot be directly sold as gasoline products. In recent years, there is still room for growth in gasoline consumption in China, while diesel consumption has already reached its peak, and the diesel-to-gasoline ratio has been continuously decreasing and is currently below 0.9. For the product structure transformation of coal synthetic oil hydrocracking enterprises to adapt to the drastic market changes and thus maximize the economic benefits of enterprises, it is necessary to change the catalyst grading system for coal synthetic oil hydrocracking in order to achieve the purpose of producing high-octane gasoline and high-cetane diesel. The paraffin content in the feedstock oil of indirect coal liquefaction is high. If the paraffins in coal synthetic oil can be selectively isomerized and cracked into naphtha to produce gasoline components with high octane number and high iso-paraffin content, and after cracking and isomerization of diesel components, the pour point of diesel can also be significantly reduced.

[0003] There are many reports on the production of diesel fractions by the hydrocracking method of coal synthetic oil, but there are few reports on the production of high-octane gasoline and low-freezing diesel from coal synthetic oil. CN 1854264 discloses an integrated hydro-upgrading method for Fischer-Tropsch synthetic oil, which aims to obtain the maximum amount of high-quality middle distillate products. After separation of the products obtained by the reaction of Fischer-Tropsch synthetic oil with hydrofining and cracking catalysts, middle distillate oil, naphtha and tail oil are obtained. The tail oil fraction reacts with a hydroisomerization catalyst and the resulting product is recycled to a high-pressure separator to obtain a low-freezing diesel component. This method can obtain more than 80% of diesel components with a high cetane number.

[0004] CN 107033954A discloses a method for hydro-upgrading Fischer-Tropsch synthetic oil. In this method, the Fischer-Tropsch synthetic oil first undergoes a hydrofining reaction, and then the effluent from the hydrofining reaction is separated to obtain a heavy oil fraction, and the heavy oil fraction is further subjected to an isomerization cracking reaction, and then the effluent from the isomerization hydrocracking reaction is separated to obtain a tail oil fraction. The hydro-upgrading method for Fischer-Tropsch synthetic oil proposed by this invention can improve the selectivity of middle distillate oil. Summary of the Invention

[0005] The technical problem to be solved by the present invention is how to subject the paraffins in coal synthetic oil to selective isomerization cracking to naphtha and diesel components, and the produced naphtha product is separated into normal and isomeric components to obtain ethylene cracking feedstock and high-octane gasoline, and the cetane number and pour point of the diesel product can both meet the national VI diesel standard.

[0006] A hydrocracking method for coal synthetic oil of the present invention comprises the following steps:

[0007] (1) The coal synthetic oil reacts with the hydrofining catalyst in the hydrofining reaction zone to remove oxygen atoms and olefins in the feedstock oil, and the hydrofining effluent contacts the hydrocracking catalyst in the hydrocracking reaction zone and undergoes isomerization and cracking reactions;

[0008] (2) The hydrofining reaction zone usually includes 2 to 6 beds, and the hydrocracking reaction zone usually includes 2 to 5 beds. Each bed is filled with a hydrocracking catalyst containing ZSM-5@β composite molecular sieve;

[0009] (3) The hydrocracking reaction effluent passes through a fractionation system to obtain dry gas, liquefied gas, naphtha, diesel, and tail oil components; the end point of the naphtha is 165 to 210 °C, and the initial boiling point of the tail oil is 300 to 380 °C;

[0010] (4) The naphtha produced by the coal synthetic oil hydrocracking unit is separated by a normal and isomeric adsorption separation unit to obtain components rich in normal paraffins and components rich in isoparaffins; the naphtha fraction rich in normal paraffins can be directly used as the feedstock for steam cracking to produce ethylene, while the component rich in isoparaffins can be used as a high-quality blending component for national VI gasoline.

[0011] Further, the catalyst described in step (1) usually includes that the hydrofining catalyst can be prepared according to the existing patent method or industrial catalysts such as FZC-33, FF-33, FF-36, FF-56, FF-36, and FF-76 developed by Dalian Petrochemical Research Institute can be used.

[0012] Further, the hydrocracking catalyst described in step (2) includes a carrier, an active metal, and a binder. The H-type ZSM-5@β composite molecular sieve synthesized by the above method is used as the acidic component, and the carrier is alumina or a mixture of amorphous silica-alumina and ZSM-5@β composite molecular sieve. The binder is usually alumina or silica. The active metal component is a metal, metal oxide, or metal sulfide of Group VI, Group VII, or Group VIII, and more preferably one or several of iron, chromium, molybdenum, tungsten, cobalt, nickel, or their sulfides or oxides. Based on the weight of the catalyst, the content of the active component is usually 10 to 35 wt%.

[0013] Furthermore, the ZSM-5@β composite molecular sieve with a core-shell structure has β molecular sieve as the core and ZSM-5 molecular sieve as the shell, where the theoretical mass ratio of β molecular sieve to ZSM-5 molecular sieve is 1:15 to 1:25. The total silica-alumina ratio of the composite molecular sieve is 20 to 60, the infrared acid amount is 0.1 to 0.4 mmol / g, the average pore diameter is 5.0 to 7.0 nm, the specific surface area is 220 to 380 m 2 / g, and the pore volume is 0.18 to 0.50 cm 3 / g. The described ZSM-5@β composite molecular sieve can be prepared by a conventional method in the art or according to the method provided by the present invention.

[0014] Furthermore, the present invention also provides a method for preparing the ZSM-5@β composite molecular sieve. Specifically, the method is as follows:

[0015] (a) First, synthesize the nanocrystalline seeds of β molecular sieve, and control the silica-alumina ratio of the feedstock to be 40 to 90; use silica sol as the silicon source and tetraethylammonium hydroxide (TEAOH) as the template agent, and fully stir and mix them in a mass ratio of 1:1 to 1:7 as the mixed solution I; use aluminum isopropoxide as the aluminum source and an aqueous solution of NaOH as the reaction medium, with aluminum isopropoxide:H 2 O:NaOH = 1:50 to 300:0.06 to 1 (mass ratio), and stir the prepared mixed solution II at 15 to 35 °C for 2 to 6 h; then, pour the mixed solution II into the mixed solution I, and transfer the mixed solution of the two to a crystallization kettle, and crystallize at 120 to 160 °C for 12 to 96 h to obtain nanoscale β molecular sieve;

[0016] (b) Secondly, prepare the ZSM-5 synthesis emulsion, and control the silica-alumina ratio of the feedstock to be 10 to 40; use silica sol and tetrapropylammonium hydroxide (TPAOH) as the template agent, and add a certain amount of water as the dissolution medium, and the mass ratio of the three is TEOS:H 2 O:TPAOH = 1:1 to 5:1 to 6, and after the three are fully dissolved, it is recorded as the mixed solution III; use aluminum isopropoxide as the aluminum source and an aqueous solution of NaOH as the reaction medium, with aluminum isopropoxide:H 2 O:NaOH = 1:1 to 12:0.6 to 3 (mass ratio), and stir the prepared solution IV at 15 to 35 °C for 2 to 6 h; add the solution III and the β molecular sieve seeds to the solution IV and stir for 2 to 6 h, then transfer the mixed solution to a crystallization kettle and crystallize at 120 to 160 °C for 12 to 96 h; the solution in the crystallization kettle is filtered, washed with water and then dried (usually dried in an oven at 50 to 100 °C for 6 to 18 h); the dried solid is transferred to a muffle furnace and calcined at 400 to 600 °C for 4 to 10 h to obtain the Na-type ZSM-5@β composite molecular sieve;

[0017] (c) Using an aqueous ammonium chloride solution as the ammonium exchange medium and an exchange temperature of 70-95 °C, the Na-type ZSM-5@β composite molecular sieve prepared above is subjected to two ammonium exchanges and calcined at 400-600 °C for 2-8 h, and finally an H-type ZSM-5@β composite molecular sieve is obtained.

[0018] Further, the diesel component described in step (3) can be used as a blending component for national VI diesel, or as a cracking raw material for steam cracking to produce ethylene, or can be recycled to the refining reaction zone or the cracking reaction zone for deep cracking to maximize the production of high-octane gasoline components. The tail oil component is recycled to the inlet of the hydrofining reactor or the hydrocracking reactor for deep cracking.

[0019] Further, the n-paraffin and i-paraffin separation device for naphtha described in step (4) is divided into an adsorption unit, a purge unit, and a desorption unit. The operating conditions of a typical adsorption unit are: pressure 0.1-1.6 MPa, temperature 150-360 °C, liquid-phase volume space velocity 0.4-5 h -1 , adsorption time 10-30 min. The operating conditions of a typical purge unit are: purge pressure 0.1-1.8 MPa, temperature 150-360 °C, volume space velocity 40-120 h -1 , purge time 5-15 min. The operating conditions of a typical desorption unit are: pressure 0.2-1.6 MPa, temperature 150-360 °C, volume space velocity 40-120 h -1 , desorption time 5-15 min.

[0020] Further, in the hydrocracking process of coal-derived synthetic oil involved in the present invention, the reaction conditions in the hydrofining and hydrocracking reaction zones are generally: reaction pressure 4.0-14.0 MPa, preferably 5.0-12.0 MPa; average reaction temperature 280-420 °C, preferably 310-410 °C; hydrofining volume space velocity 0.5-8.0 h -1 , preferably 0.5-3.0 h -1 ; hydrocracking volume space velocity 0.6-10.0 h -1 , preferably 1.0-3.0 h -1 ; hydrogen-oil volume ratio 400:1-1800:1, preferably 600:1-1200:1.

[0021] In the hydrocracking catalyst of the present invention, ZSM-5 zeolite and β zeolite are compounded to prepare ZSM-5@β with a core-shell structure as the cracking active component. When most of the paraffins in coal-derived synthetic oil contact the shell layer of ZSM-5 and crack into small molecules, and then continue to contact the β zeolite in the core layer, the paraffin components in coal-derived synthetic oil can be cracked into naphtha to the greatest extent at a lower temperature. Moreover, it can ensure that most of the paraffins in naphtha are isoparaffins, and the octane number of the obtained naphtha can also be significantly improved.

[0022] The coal-derived synthetic oil hydrocracking method provided by the present invention can be used in any hydrocracking field. It is particularly suitable for the hydrocracking of coal-derived synthetic oil to produce high-octane gasoline and low-freezing diesel components, can significantly increase the content of isoparaffins and the octane number in gasoline components, and achieve the purpose of reducing the diesel-gasoline ratio.

[0023] Compared with the prior art, the beneficial effects of the method of the present invention are as follows:

[0024] 1. Using coal-derived synthetic oil as the raw material for hydrocracking reaction, the obtained naphtha has a high paraffin content. After normal and isomer separation, the obtained gasoline components have a high isoparaffin content and can be directly used as blending components for national VI gasoline, while the components rich in normal paraffins can be directly used as raw materials for steam cracking to ethylene.

[0025] 2. Selecting the ZSM-5@β composite zeolite with strong paraffin cracking and isomerization ability as the acidic center can effectively isomerize and crack the paraffins in diesel into naphtha components to produce high-octane gasoline.

[0026] 3. Adopting a single-stage series full-circulation process flow, compared with the traditional coal-derived synthetic oil hydrocracking process, the processing route is significantly shortened and the investment is less. After the tail oil is fully circulated, the gasoline yield is higher and the diesel-gasoline ratio can be significantly reduced. Description of the Drawings

[0027] Figure 1 XRD spectra of the composite zeolite, conventional ZSM-5 and Beta zeolite synthesized in the examples. Detailed Embodiments

[0028] The coal-derived synthetic oil hydrocracking method provided by the present invention will be further described below in conjunction with the examples, but the present invention is not limited thereto.

[0029] Table 1 Properties of the feedstock oil.

[0030]

[0031] Table 2 Industrial catalysts.

[0032] Industrial agent FF-36 FC-16 FC-32A Physical and chemical properties Pore size / nm 2 - 10 nm 2 - 8 nm 2 - 8 nm <![CDATA[Pore volume / mL·g -1 > ≥0.30 ≥0.28 ≥0.25 <![CDATA[Specific surface area / m 2 ·g -1 > ≥170 ≥300 ≥300 Shape Toothed ball Toothed ball Toothed ball <![CDATA[Loading heap ratio, g / cm 3 > 0.75 0.83 0.80

[0033] Table 3 Evaluation conditions.

[0034]

[0035] The feedstock oil used in the following examples and comparative examples is coal synthetic oil, and its properties are shown in Table 1. The first-stage refining reactor is filled with FF-36 hydrofining catalyst, and the hydrocracking reactor is filled with hydrocracking catalyst. The naphtha distillation range in the examples and comparative examples is <205 °C, and the initial boiling point of the tail oil is 350 °C.

[0036] Three kinds of ZSM-5@β composite molecular sieves with different properties are used in this example, and their synthesis methods are as follows:

[0037] ZSM-5@β composite molecular sieve 1

[0038] (1) First, synthesize the nanocrystalline seeds of β molecular sieve, and the silicon-aluminum ratio of the feedstock is 45. Using silica sol and tetraethylammonium hydroxide (TEAOH) as the template agent, after fully stirring and mixing in a mass ratio of 1:1.5, it is used as mixed solution I; using aluminum isopropoxide as the aluminum source and an aqueous solution of NaOH as the reaction medium, the mass ratio of aluminum isopropoxide, H 2 O and NaOH is 1:110:0.2. The prepared mixed solution II is stirred at 30 °C for 4 h. Subsequently, mixed solution II is poured into mixed solution I, and the mixed solution of the two is transferred to a crystallization kettle and crystallized at 145 °C for 48 h to obtain nanoscale β molecular sieve seeds.

[0039] (2) Secondly, prepare the ZSM-5 molecular sieve synthesis emulsion, and the silicon-aluminum ratio of the feedstock is 10. Using silica sol and tetrapropylammonium hydroxide (TPAOH) as the template agent, and adding a certain amount of water as the dissolution medium, the mass ratio of the three is TEOS: H 2 O:TPAOH = 1:3:5. After the three are fully dissolved, it is denoted as mixed solution III; using aluminum isopropoxide as the aluminum source and an aqueous solution of NaOH as the reaction medium, aluminum isopropoxide: H 2 O:NaOH = 1:4:1.5 (mass ratio). The prepared solution IV is stirred at 30 °C for 3 h. Solution III and the β molecular sieve seeds are added to solution IV and stirred for 3 h. Subsequently, the mixed solution is transferred to a crystallization kettle and crystallized at 140 °C for 46 h. The solution in the crystallization kettle is filtered, washed with water, and then placed in an oven at 80 °C for drying for 10 h. The dried solid is transferred to a muffle furnace and calcined at 520 °C for 5 h to obtain the Na-type ZSM-5@β composite molecular sieve.

[0040] (3) Using an aqueous solution of ammonium chloride as the ammonium exchange medium and an exchange temperature of 90 °C, the Na-type ZSM-5@β composite molecular sieve prepared above was subjected to two ammonium exchanges and calcined at 500 °C for 3 h, and finally the H-type ZSM-5@β composite molecular sieve 1 was obtained. The theoretical mass ratio of β molecular sieve to ZSM-5 molecular sieve in the composite molecular sieve 1 is 1:15, the infrared acid amount is 0.15 mmol / g, the average pore diameter is 5.8 nm, the specific surface area is 240 m 2 / g, and the pore volume is 0.35 cm 3 / g.

[0041] ZSM-5@β composite molecular sieve 2

[0042] (1) First, nanocrystalline seeds of β molecular sieve were synthesized, and the silicon-aluminum ratio of the feedstock was 65. Using silica sol and tetraethylammonium hydroxide (TEAOH) as template agents, they were fully stirred and mixed in a mass ratio of 1:1.5 to form a mixed solution I; using aluminum isopropoxide as the aluminum source and an aqueous solution of NaOH as the reaction medium, the mass ratio of aluminum isopropoxide, H 2 O and NaOH is 1:110:0.2. The prepared mixed solution II was stirred at 30 °C for 4 h. Subsequently, the mixed solution II was poured into the mixed solution I, and the mixed solution of the two was transferred to a crystallization kettle and crystallized at 145 °C for 48 h to obtain nanoscale β molecular sieve seeds.

[0043] (2) Secondly, a ZSM-5 molecular sieve synthesis emulsion was prepared, and the silicon-aluminum ratio of the feedstock was 20. Using silica sol and tetrapropylammonium hydroxide (TPAOH) as template agents and adding a certain amount of water as a dissolution medium, the mass ratio of the three is TEOS: H 2 O:TPAOH = 1:3:5. After the three were fully dissolved, it was denoted as mixed solution III; using aluminum isopropoxide as the aluminum source and an aqueous solution of NaOH as the reaction medium, aluminum isopropoxide: H 2 O:NaOH = 1:4:1.5 (mass ratio). The prepared solution IV was stirred at 30 °C for 3 h. Solution III and the β molecular sieve seeds were added to solution IV and stirred for 3 h. Subsequently, the mixed solution was transferred to a crystallization kettle and crystallized at 140 °C for 46 h. The solution in the crystallization kettle was filtered, washed with water, and then placed in an oven at 80 °C for drying for 10 h. The dried solid was transferred to a muffle furnace and calcined at 520 °C for 5 h to obtain the Na-type ZSM-5@β composite molecular sieve.

[0044] (3) Using an aqueous solution of ammonium chloride as the ammonium exchange medium and an exchange temperature of 90 °C, the Na-type ZSM-5@β composite molecular sieve prepared above was subjected to two ammonium exchanges and calcined at 500 °C for 3 h, and finally H-type ZSM-5@β composite molecular sieve 2 was obtained. The theoretical mass ratio of β molecular sieve to ZSM-5 molecular sieve in composite molecular sieve 2 is 1:20, the infrared acid amount is 0.20 mmol / g, the average pore diameter is 6.2 nm, the specific surface area is 290 m 2 / g, and the pore volume is 0.45 cm 3 / g.

[0045] ZSM-5@β composite molecular sieve 3

[0046] (1) First, nanocrystalline seeds of β molecular sieve were synthesized, and the silicon-aluminum ratio of the feedstock was 90. Using silica sol and tetraethylammonium hydroxide (TEAOH) as template agents, they were fully stirred and mixed in a mass ratio of 1:1.5 to form mixed solution I; using aluminum isopropoxide as the aluminum source and an aqueous solution of NaOH as the reaction medium, the mass ratio of aluminum isopropoxide, H 2 O and NaOH was 1:110:0.2, and the prepared mixed solution II was stirred at 30 °C for 4 h. Subsequently, mixed solution II was poured into mixed solution I, and the mixed solution of the two was transferred to a crystallization kettle and crystallized at 145 °C for 48 h to obtain nanoscale β molecular sieve seeds.

[0047] (2) Secondly, a ZSM-5 molecular sieve synthesis emulsion was prepared, and the silicon-aluminum ratio of the feedstock was 40. Using silica sol and tetrapropylammonium hydroxide (TPAOH) as template agents and adding a certain amount of water as the dissolution medium, the mass ratio of the three was TEOS: H 2 O:TPAOH = 1:3:5, and after the three were fully dissolved, it was denoted as mixed solution III; using aluminum isopropoxide as the aluminum source and an aqueous solution of NaOH as the reaction medium, aluminum isopropoxide: H 2 O:NaOH = 1:4:1.5 (mass ratio), and the prepared solution IV was stirred at 30 °C for 3 h. Solution III and β molecular sieve seeds were added to solution IV and stirred for 3 h, and then the mixed solution was transferred to a crystallization kettle and crystallized at 140 °C for 46 h. The solution in the crystallization kettle was filtered, washed with water, and then placed in an oven at 80 °C and dried for 10 h. The dried solid was transferred to a muffle furnace and calcined at 520 °C for 5 h to obtain Na-type ZSM-5@β composite molecular sieve.

[0048] (3) Using an aqueous solution of ammonium chloride as the ammonium exchange medium and an exchange temperature of 90 °C, the Na-type ZSM-5@β composite zeolite prepared above was subjected to two ammonium exchanges and calcined at 500 °C for 3 h, and finally the H-type ZSM-5@β composite zeolite 3 was obtained. The theoretical mass ratio of β zeolite to ZSM-5 zeolite in the composite zeolite 3 is 1:20, the infrared acid amount is 0.15 mmol / g, the average pore diameter is 5.9 nm, the specific surface area is 270 m 2 / g, and the pore volume is 0.40 cm 3 / g.

[0049] The XRD patterns of the above three synthesized composite zeolites are as Figure 1 shown. As can be seen from the figure, the XRD pattern of the composite zeolite contains the characteristic peaks of ZSM-5 and β zeolite, indicating the successful synthesis of the ZSM-5@β composite zeolite.

[0050] Example 1

[0051] Using the H-type ZSM-5@β composite zeolite 1 synthesized by the above method and alumina as the carrier, the mass fraction of the H-type ZSM-5@β composite zeolite in the carrier is 15%, and the active metals Ni and Mo are loaded, and the content of the active metals is 20 wt%. After calcination at 510 °C, NiMo / ZSM-5@β-Al 2 O 3 hydrocracking catalyst was obtained. The above-prepared hydrocracking catalyst was loaded into a hydrocracking reactor, and an industrial hydrofining catalyst FF-36 was loaded into the hydrofining reactor. Using coal-derived synthetic oil as the raw material, it was evaluated according to the process conditions in Table 3 to obtain naphtha and diesel products. After passing the naphtha product through a normal-isomer separation device, the properties of all products were analyzed.

[0052] Example 2

[0053] Using the H-type ZSM-5@β composite zeolite 2 synthesized by the above method and alumina as the carrier, the mass fraction of the H-type ZSM-5@β composite zeolite in the carrier is 18%, and the active metals Ni and Mo are loaded, and the content of the active metals is 21 wt%. After calcination at 500 °C, NiMo / ZSM-5@β-Al 2 O 3 hydrocracking catalyst was obtained. The above-prepared hydrocracking catalyst was loaded into a hydrocracking reactor, and an industrial hydrofining catalyst FF-36 was loaded into the hydrofining reactor. Using coal-derived synthetic oil as the raw material, it was evaluated according to the process conditions in Table 3 to obtain naphtha and diesel products. After passing the naphtha product through a normal-isomer separation device, the properties of all products were analyzed.

[0054] Example 3

[0055] The H-type ZSM-5@β composite molecular sieve 3 synthesized by the above method and alumina are used as carriers. The mass fraction of the H-type ZSM-5@β composite molecular sieve in the carrier is 23%, and active metals Ni and Mo are loaded, with the active metal content being 23 wt%. After calcination at 500 °C, the NiMo / ZSM-5@β-Al 2 O 3 hydrocracking catalyst is obtained. The above-prepared hydrocracking catalyst is loaded into a hydrocracking reactor, and an industrial hydrofining catalyst FF-36 is loaded into the hydrofining reactor. Using coal-derived synthetic oil as the raw material, evaluation is carried out according to the process conditions in Table 3 to obtain naphtha and diesel products. After passing the naphtha product through a normal and isomer separation device, the properties of all products are analyzed.

[0056] Example 4

[0057] The H-type ZSM-5@β composite molecular sieve 3 synthesized by the above method and alumina are used as carriers. The mass fraction of the H-type ZSM-5@β composite molecular sieve in the carrier is 32%, and active metals Ni and W are loaded, with the active metal content being 26 wt%. After calcination at 500 °C, the NiW / ZSM-5@β-Al 2 O 3 hydrocracking catalyst is obtained. The above-prepared hydrocracking catalyst is loaded into a hydrocracking reactor, and an industrial hydrofining catalyst FF-36 is loaded into the hydrofining reactor. Using coal-derived synthetic oil as the raw material, evaluation is carried out according to the process conditions in Table 3 to obtain naphtha and diesel products. After passing the naphtha product through a normal and isomer separation device, the properties of all products are analyzed.

[0058] Comparative Example 1

[0059] An industrial hydrocracking catalyst FC-16 is loaded into a hydrocracking reactor, and an industrial hydrofining catalyst FF-36 is loaded into the hydrofining reactor. Using coal-derived synthetic oil as the raw material, evaluation is carried out according to the process conditions in Table 3 to obtain naphtha and diesel products. After passing the naphtha product through a normal and isomer separation device, the properties of all products are analyzed.

[0060] Comparative Example 2

[0061] An industrial hydrocracking catalyst FC-32A is loaded into a hydrocracking reactor, and an industrial hydrofining catalyst FF-36 is loaded into the hydrofining reactor. Using coal-derived synthetic oil as the raw material, evaluation is carried out according to the process conditions in Table 3 to obtain naphtha and diesel products. After passing the naphtha product through a normal and isomer separation device, the properties of all products are analyzed.

[0062] Comparative Example 3

[0063] The industrial hydrocracking catalysts FC-16 / FC-32A are loaded into the hydrocracking reactor after being proportioned at a ratio of 1:1, and the industrial hydrofining catalyst FF-36 is loaded into the hydrofining reactor. Using coal-derived synthetic oil as the raw material, the evaluation is carried out according to the process conditions in Table 3 to obtain naphtha and diesel products. After passing the naphtha product through the normal and isomer separation device, the properties of all products are analyzed.

[0064] Table 4 Test results of the examples.

[0065]

[0066] Table 5 Test results of the comparative examples.

[0067]

[0068] It can be seen from the experimental results of the comparative examples and the examples that, under the condition of controlling the same single-pass conversion rate, when the ZSM-5@β composite molecular sieve prepared by the present invention is used as the carrier component, the octane number of the produced naphtha is above 85, and after normal and isomer separation, the octane number of the raffinate oil rich in isoparaffins can reach above 94. When the catalyst in Example 4 is used, the highest octane number of the naphtha produced by the hydrocracking of coal-derived synthetic oil is 96.8 after normal and isomer separation.

Claims

1. A hydrocracking method for coal synthetic oil, characterized in that, it comprises the following steps: (1) The coal synthetic oil reacts with the hydrofining catalyst in the hydrofining reaction zone to remove oxygen atoms and olefins in the feedstock oil. The hydrofining effluent contacts the hydrocracking catalyst in the hydrocracking reaction zone and undergoes isomerization and cracking reactions; (2) The hydrofining reaction zone includes 2 to 6 beds, and the hydrocracking reaction zone includes 2 to 5 beds. The hydrocracking catalyst containing ZSM-5@β composite molecular sieve is loaded in each bed of the hydrocracking reaction zone; (3) The hydrocracking reaction effluent passes through a fractionation system to obtain dry gas, liquefied gas, naphtha, diesel, and tail oil components; the end point of the naphtha is 165 to 210 °C, and the initial boiling point of the tail oil is 300 to 380 °C; (4) The naphtha obtained in step (3) passes through a normal and isomer adsorption separation device to obtain components rich in normal paraffins and components rich in isoparaffins; the naphtha component rich in normal paraffins is used as a raw material for steam cracking to produce ethylene, while the component rich in isoparaffins is used as a blending component for national VI gasoline; wherein, the ZSM-5@β composite molecular sieve has a β molecular sieve as the core and a ZSM-5 molecular sieve as the shell, and the theoretical mass ratio of the β molecular sieve to the ZSM-5 molecular sieve is 1:15 to 1:25; The total silica-alumina ratio of the composite molecular sieve is 20 to 60, the infrared acid amount is 0.1 to 0.4 mmol / g, the average pore diameter is 5.0 to 7.0 nm, the specific surface area is 220 to 380 m 2 / g, and the pore volume is 0.18 to 0.50 cm 3 / g; Based on the weight of the hydrocracking catalyst, the active component content is 10 to 35 wt%.

2. The hydrocracking method according to claim 1, characterized in that, the tail oil component obtained in step (3) is recycled to the inlet of the hydrofining reaction zone or the hydrocracking reaction zone.

3. The hydrocracking method according to claim 1, characterized in that, in the hydrocracking catalyst, the ZSM-5@β composite molecular sieve is an acidic component, the carrier is alumina or / and amorphous silica-alumina, and a mixture of the ZSM-5@β composite molecular sieve, and the active metal component is a metal, metal oxide or metal sulfide of Group VI, Group VII or Group VIII.

4. The hydrocracking method according to claim 3, characterized in that, the active metal component of the hydrocracking catalyst is one or more of iron, chromium, molybdenum, tungsten, cobalt, nickel, or their sulfides or oxides.

5. The hydrocracking method according to claim 1, characterized in that, The reaction conditions in the hydrofining reaction zone and the hydrocracking reaction zone are as follows: the reaction pressure is 4.0 - 14.0 MPa, the average reaction temperature is 280 - 420 °C, the volumetric space velocity of hydrofining is 0.5 - 8.0 h -1 , the volumetric space velocity of hydrocracking is 0.6 - 10.0 h -1 , and the hydrogen-to-oil volume ratio is 400:1 - 1800:

1.

6. The hydrocracking method according to claim 5, characterized in that, The reaction conditions in the hydrofining reaction zone and the hydrocracking reaction zone are as follows: the reaction pressure is 5.0 - 12.0 MPa, the average reaction temperature is 310 - 410 °C, the volumetric space velocity of hydrofining is 0.5 - 3.0 h -1 , the volumetric space velocity of hydrocracking is 1.0 - 3.0 h -1 , and the hydrogen-to-oil volume ratio is 600:1 - 1200:

1.

7. The hydrocracking method according to claim 1, characterized in that, in step (3), the diesel component is used as a blending component for national VI diesel, or a raw material for steam cracking to produce ethylene, or recycled to the refining reaction zone or the cracking reaction zone.

8. The hydrocracking method according to claim 1, characterized in that, The normal and isomer adsorption separation device includes an adsorption unit, a purging unit and a desorption unit: The operating conditions of the adsorption unit are: pressure 0.1 - 1.6 MPa, temperature 150 - 360 °C, liquid-phase volume space velocity 0.4 - 5 h -1 , adsorption time 10 - 30 min; The operating conditions of the purging unit are: purging pressure 0.1 - 1.8 MPa, temperature 150 - 360 °C, volume space velocity 40 - 120 h -1 , purging time 5 - 15 min; The operating conditions of the desorption unit are: pressure 0.2 - 1.6 MPa, temperature 150 - 360 °C, volume space velocity 40 - 120 h -1 , desorption time 5 - 15 min.

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