A method for producing more chemical raw materials from crude oil

Abstract

The present invention discloses a method for producing more chemical raw materials from crude oil. The method includes: the crude oil is subjected to atmospheric distillation to obtain the overhead oil of the atmospheric column; the overhead oil of the atmospheric column is mixed with hydrogen and enters the first hydrocracking reaction zone for the first hydrocracking, and the mass content of C7 + n-alkanes in the first hydrocracking product is controlled to be 0.1% to 5.0%; the first hydrocrackate enters the second hydrocracking reaction zone to obtain the second hydrocracking product, and then is separated and fractionated to obtain gas, light naphtha, heavy naphtha and tail oil; the tail oil is mixed with hydrogen and enters the third hydrocracking reaction zone to obtain the third hydrocracking product containing monocyclic hydrocarbons, and the third hydrocracking product enters the separation and fractionation system to obtain gas, light naphtha and heavy naphtha; the reaction pressure of the first hydrocracking reaction zone is 5 to 10 MPa; the reaction pressure of the third hydrocracking reaction zone is 2 to 6 MPa. This method can significantly improve the quality and yield of chemical raw materials.

Description

Technical Field

[0001] The present invention relates to a method for producing more chemical raw materials from crude oil, and particularly to a processing method for converting light components in crude oil into chemical raw materials through hydrocracking. Background Art

[0002] With the rapid development of electric vehicles and hydrogen fuel cell vehicles, as well as the improvement of the fuel economy of internal combustion engines, the growth rate of refined oil consumption has continued to slow down. However, the demand for bulk petrochemical raw materials such as light olefins (ethylene, propylene, butene) and aromatics (benzene, toluene, xylene, abbreviated as BTX) still maintains a relatively high growth rate, becoming the main driving force for the growth of crude oil demand. In this new situation, producing chemical raw materials from crude oil has become one of the main means for refinery and petrochemical enterprises to transform and upgrade, improve quality and increase efficiency. From the perspective of the yield of converting crude oil into chemical raw materials, the yield of chemical raw materials in the traditional fuel-type refinery model is 8% - 12%, the yield of chemical raw materials in the conventional refinery-petrochemical integrated plant is 10% - 20%, while the yield of chemical raw materials in the crude oil-to-chemical raw materials plant can reach 40% or even up to 80%. Therefore, the technology of producing chemical raw materials from crude oil has received great attention.

[0003] The ethylene industry is the core of the petrochemical industry and one of the important symbols to measure the petrochemical development level of a country. Therefore, improving the production capacity of ethylene is an important way for petrochemical technology and product innovation. Further optimizing the raw material structure, deeply exploring the potential for integrated efficiency improvement, and increasing the proportion of light and low-grade raw materials in ethylene cracking feedstock are still important tasks for Chinese steam cracking ethylene enterprises to reduce the production cost of olefins. The hydrocracking technology has the characteristics of strong raw material adaptability, great flexibility in production operation and product scheme, and good product quality. It can directly convert various heavy and inferior feeds into high-quality jet fuels, diesel oils, lubricating oil base stocks, chemical naphtha and tail oil for steam cracking to produce ethylene raw materials that are in urgent need in the market. It has become one of the most important heavy oil deep processing processes in modern refining and petrochemical industries and has been increasingly widely used at home and abroad. Crude oil is fractionated by atmospheric and vacuum distillation to obtain products in different distillation sections. The more different distillation sections are separated, the higher the energy consumption. Converting different fractions in crude oil into chemical raw materials with lower energy consumption has become a beneficial technical path for refining enterprises to optimize product structure and improve economic benefits.

[0004] CN201580070326.4 discloses a method for preparing LPG and BTX, comprising: a) subjecting a mixed hydrocarbon stream to a first hydrocracking in the presence of a first hydrocracking catalyst to prepare a first hydrocracking product stream; b) separating the first hydrocracking product stream to provide at least one light hydrocarbon stream comprising at least C2 and C3 hydrocarbons, an intermediate hydrocarbon stream consisting of C4 and / or C5 hydrocarbons, and a heavy hydrocarbon stream comprising at least C6+ hydrocarbons, and c) subjecting the heavy hydrocarbon stream to a second hydrocracking in the presence of a second hydrocracking catalyst to prepare a second hydrocracking product stream comprising BTX, wherein the second hydrocracking is more severe than the first hydrocracking, d) wherein at least part of the intermediate hydrocarbon stream is subjected to C4 hydrocracking in the presence of a C4 hydrocracking catalyst to prepare a C4 hydrocracking product stream, and the C4 hydrocracking is optimized for converting C4 hydrocarbons into C3 hydrocarbons.

[0005] CN201480037272.7 discloses a method for producing light olefin hydrocarbon compounds from a hydrocarbon feedstock, comprising the following steps: (a) feeding the hydrocarbon feedstock to a reaction zone for ring opening; (b) separating the reaction product produced by the reaction zone into an overhead stream and a side stream; (c) feeding the side stream from (b) to a gasoline hydrocracker (GHC) unit; (d) separating the reaction product of the GHC in step (c) into an overhead stream comprising hydrogen, methane, ethane and liquefied petroleum gas and a stream comprising aromatic hydrocarbon compounds and a small amount of hydrogen and non-aromatic hydrocarbon compounds; (e) feeding the overhead stream from the gasoline hydrocracker (GHC) unit to a steam cracker unit.

[0006] In summary, petroleum hydrocarbons have a complex composition, mainly including alkanes, cycloalkanes and aromatics. Among them, alkanes, especially small-molecule alkanes, are high-quality ethylene raw materials, while cycloalkanes and aromatics are high-quality reforming feeds. In the prior art, for the conversion of crude oil, it is impossible to achieve the mixed processing of different fractions, nor can it selectively enrich alkanes (including long side chains on cyclic hydrocarbons) efficiently into ethylene raw materials and enrich cyclic hydrocarbons into reforming raw materials. Therefore, in view of the above problems, it is of great significance to develop an excellent processing method for producing high-quality chemical raw materials. Summary of the Invention

[0007] Aiming at the problems existing in the prior art, the object of the present invention is to provide a method for producing more chemical raw materials from crude oil. This method uses the overhead oil of the atmospheric tower as the raw material, which can greatly improve the quality and yield of chemical products.

[0008] The present invention provides a method for producing more chemical raw materials from crude oil, and the method comprises:

[0009] (1) The crude oil is subjected to atmospheric distillation to obtain the overhead oil of the atmospheric tower;

[0010] (2) The overhead oil from the atmospheric distillation column obtained in step (1) is mixed with hydrogen and enters the first hydrocracking reaction zone for the first hydrocracking, and the mass content of C7 + n - paraffin in the first hydrocracking product is controlled to be 0.1% - 5.0%;

[0011] (3) The reaction effluent from step (2) enters the second hydrocracking reaction zone to selectively open - ring and crack the poly - cyclic hydrocarbons above bicyclic to obtain the second hydrocracking product; the hydrogen - rich gas obtained after the gas - liquid separation of the second hydrocracking product through a separator is used as recycle hydrogen, and the liquid phase enters the fractionation system for fractionation to obtain gas, light naphtha, heavy naphtha and tail oil;

[0012] (4) The tail oil from step (3) is mixed with hydrogen and enters the third hydrocracking reaction zone to obtain the third hydrocracking product containing monocyclic hydrocarbons, and the third hydrocracking product enters the separation and fractionation system to obtain gas, light naphtha and heavy naphtha;

[0013] In step (2), the reaction pressure of the first hydrocracking reaction zone is 5 - 10 MPa; in step (4), the reaction pressure of the third hydrocracking reaction zone is 2 - 6 MPa.

[0014] According to the present invention, the properties of the crude oil in step (1) are as follows: the density is 0.80 g / cm 3 ~1.10 g / cm 3 , preferably 0.85 g / cm 3 ~1.0 g / cm 3 ; the nitrogen mass content is 0.1% - 0.6%, preferably 0.2% - 0.5%; the sulfur mass content is 1% - 6%, preferably 2% - 4%; the metal content is 10 mg / kg - 100 mg / kg, preferably 20 mg / kg - 60 mg / kg.

[0015] According to the present invention, the atmospheric distillation conditions in step (1) are as follows: the overhead pressure is 0.04 MPa - 0.12 MPa, preferably 0.06 MPa - 0.10 MPa; the atmospheric distillation feed temperature is 330 °C - 390 °C, preferably 350 °C - 370 °C.

[0016] According to the present invention, the initial boiling point of the overhead oil from the atmospheric distillation column in step (1) is 50 °C - 80 °C, preferably 60 °C - 70 °C; the final boiling point is 280 °C - 340 °C, preferably 290 °C - 320 °C.

[0017] According to the present invention, the mass content of tricyclic aromatic hydrocarbons in the overhead oil from the atmospheric distillation column is not higher than 1.0%, preferably 0.2% - 0.6%.

[0018] According to the present invention, the chemical raw materials mainly include ethane, propane, butane, and light naphtha, and may also include heavy naphtha. Among them, heavy naphtha is used as a reforming raw material to produce BTX, and ethane, propane, butane, and light naphtha are used as raw materials for producing lower olefins. For example, ethylene is produced as a steam cracking raw material, and propane and butane can also be directly dehydrogenated to produce propylene and butene. Among them, lower olefins refer to olefins with four or fewer carbon atoms, especially ethylene, propylene, and butadiene.

[0019] According to the present invention, preferably, the reaction pressure in the first hydrocracking reaction zone in step (2) is 0.5 - 5.0 MPa higher than the reaction pressure in the third hydrocracking reaction zone in step (4).

[0020] According to the present invention, preferably, the reaction pressure in the first hydrocracking reaction zone in step (2) is 0.5 - 3.0 MPa higher than the reaction pressure in the third hydrocracking reaction zone in step (4).

[0021] According to the present invention, preferably, the mass content of C7 + n - paraffins in the first hydrocracking product in step (2) is 1.0% - 3.0%.

[0022] According to the present invention, the reaction conditions in the first hydrocracking reaction zone in step (2) are as follows: the reaction pressure is 6 - 8 MPa.

[0023] According to the present invention, the reaction conditions in the first hydrocracking reaction zone in step (2) are as follows: the average reaction temperature is 250 - 450 °C, preferably 300 - 400 °C; the liquid hourly space velocity is 0.1 - 15.0 h -1 , preferably 1.0 - 5.0 h -1 ; the hydrogen - to - oil volume ratio is 100:1 - 2500:1, preferably 400:1 - 2000:1.

[0024] According to the present invention, in step (2), the overhead oil of the atmospheric column may contain impurities such as sulfur and nitrogen. According to actual needs, a hydrofining catalyst can be provided upstream of the first hydrocracking catalyst to remove impurities such as sulfur and nitrogen. Among them, the nitrogen content in the reaction fluid stream in contact with the first hydrocracking catalyst is preferably below 50 mg / kg, and more preferably below 20 mg / kg.

[0025] According to the present invention, in step (2), the first hydrocracking reaction zone is filled with a first hydrocracking catalyst. The first hydrocracking catalyst can be one or more catalysts.

[0026] According to the present invention, in step (2), a hydrofining catalyst may be provided upstream of the first hydrocracking catalyst, and a conventional hydrofining catalyst can be used, which is mainly used for hydrodesulfurization, hydrodenitrogenation and other impurities. The hydrofining catalyst includes a carrier and a hydrogenation active metal, wherein the carrier is an inorganic refractory oxide, generally selected from one or more of alumina, amorphous silica-alumina, silica or titanium oxide, etc.; the hydrogenation active metal includes Group VIB and / or Group VIII metal components. In the hydrofining catalyst, Group VIB is preferably selected from tungsten and / or molybdenum, and its content in the catalyst based on the mass of the oxide is 5% to 30%, preferably 10% to 20%, and Group VIII is preferably selected from nickel and / or cobalt, and its content in the catalyst based on the mass of the oxide is 1% to 6%, preferably 1.5% to 5%. The content of the carrier in the catalyst based on the mass of the oxide is 64% to 94%, preferably 75% to 88.5%.

[0027] According to the present invention, in step (2), the first hydrocracking catalyst includes an active metal component and a carrier; the carrier includes a molecular sieve having a selective cracking effect on normal paraffins, preferably selected from one or more of ZSM-5 molecular sieve, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-35 and ZSM-38 molecular sieves, preferably ZSM-5 molecular sieve. The SiO2 / Al2O3 molar ratio of the ZSM-5 molecular sieve is 20 to 60. The carrier may further include a binder. Preferably, the binder is alumina. The active metal component includes at least one of metals of Group VIB and Group VIII. The Group VIB metal is preferably molybdenum and / or tungsten, and the Group VIII metal is preferably cobalt and / or nickel.

[0028] According to the present invention, in step (2), preferably, for the first hydrocracking catalyst, based on the weight of the catalyst, the content of the Group VIB metal (calculated as the oxide) is 5.0% to 15.0%, the content of the Group VIII metal (calculated as the oxide) is 2.0% to 5.0%, and the content of the carrier is 80.0% to 93.0%.

[0029] According to the present invention, in step (2), preferably, in the carrier of the first hydrocracking catalyst, based on the weight of the carrier, the content of the binder is 8% to 60%, and the content of the molecular sieve is 40% to 92%.

[0030] According to the present invention, in step (2), the specific surface area of the first hydrocracking catalyst is 200 - 400m 2 / g, and the pore volume is 0.25 - 0.45 mL / g.

[0031] According to the present invention, the preparation method of the first hydrocracking catalyst in step (2) can be prepared according to the conventional methods in the art. The preparation method includes the preparation of a support and the loading of active metal components. The process of preparing the support is as follows: The shape-selective cracking molecular sieve and the binder are mechanically mixed, formed, and then dried and calcined to obtain a catalyst support. The drying and calcination of the support can be carried out under conventional conditions. The conditions for drying are: drying at 100°C to 150°C for 1 to 12 hours. The conditions for calcination are: calcining at 450°C to 550°C for 2.5 to 6.0 hours.

[0032] According to the present invention, in step (2), in the preparation method of the first hydrocracking catalyst, the method for loading the active metal components is a conventional method, such as the kneading method, the impregnation method, etc., and the impregnation method is preferred. The impregnation method can be the saturated impregnation method, the excess impregnation method or the complex impregnation method, that is, the catalyst support is impregnated with a solution containing the required active components, and then dried and calcined to obtain the first hydrocracking catalyst. The conditions for drying are: drying at 100°C to 150°C for 1 to 12 hours. The conditions for calcination are: calcining at 450°C to 550°C for 2.5 to 6.0 hours.

[0033] According to the present invention, in step (3), the separation and fractionation of the second hydrocracking product and the third hydrocracking product in step (4) preferably share a set of separation and fractionation systems.

[0034] According to the present invention, in step (3), the reaction conditions in the second hydrocracking reaction zone are as follows: the reaction pressure is 6 to 8 MPa.

[0035] According to the present invention, in step (3), the reaction conditions for the second hydrocracking reaction are as follows: the average reaction temperature is 250 to 450°C, preferably 300 to 400°C; the liquid hourly space velocity is 0.1 to 15.0 h -1 , preferably 1.0 to 5.0 h -1 ; the hydrogen-oil volume ratio is 100:1 to 2500:1, preferably 400:1 to 2000:1.

[0036] According to the present invention, preferably, the first hydrocracking reaction zone and the second hydrocracking reaction zone adopt the same reaction pressure.

[0037] According to the present invention, in step (3), the second hydrocracking reaction zone is filled with a second hydrocracking catalyst. The second hydrocracking catalyst can be one or more catalysts.

[0038] According to the present invention, in step (4), the third hydrocracking reaction zone is filled with a third hydrocracking catalyst. The third hydrocracking catalyst can be one or more catalysts.

[0039] According to the present invention, the second hydrocracking catalyst in step (3) has the function of ring-opening cracking of polycyclic cyclic hydrocarbons.

[0040] According to the present invention, the third hydrocracking catalyst in step (4) has the function of selectively cracking isoparaffins or side chains of cyclic hydrocarbons and retaining monocyclic cyclic hydrocarbons.

[0041] According to the present invention, the second hydrocracking catalyst in step (3) and / or the third hydrocracking catalyst in step (4) comprise a cracking component, a hydrogenation component and a binder. The second hydrocracking catalyst and / or the third hydrocracking catalyst can be commercially available products or prepared according to the prior art. The hydrogenation component is at least one of a metal, a metal oxide, and a metal sulfide of an active metal component; the active metal component includes metals of Group VIB and / or Group VIII; the active metal component is more preferably at least one of iron, chromium, molybdenum, tungsten, cobalt, and nickel. The binder is alumina and / or silica; the cracking component includes an acidic molecular sieve, preferably at least one of Beta zeolite and Y zeolite.

[0042] According to the present invention, further preferably, the cracking component of the second hydrocracking catalyst in step (3) is Y zeolite.

[0043] According to the present invention, further preferably, the cracking component of the third hydrocracking catalyst in step (4) is Beta zeolite.

[0044] According to the present invention, in the second hydrocracking catalyst in step (3) and / or the third hydrocracking catalyst in step (4), based on the mass of the catalyst, the content of the hydrogenation component in terms of oxide is 5 wt% to 40 wt%, preferably 10 wt% to 30 wt%; the content of the cracking component is 10 wt% to 80 wt%, preferably 20 wt% to 60 wt%; the content of the binder is 5 wt% to 85 wt%, preferably 10 wt% to 50 wt%.

[0045] According to the present invention, the preparation method of the second hydrocracking catalyst in step (3) and / or the third hydrocracking catalyst in step (4) can be prepared according to the conventional methods in the art. The preparation method includes the preparation of a support and the loading of a hydrogenation component, wherein the preparation process of the support is as follows: the cracking component and the binder are mechanically mixed, shaped, and then dried and calcined to make a catalyst support. The drying and calcination of the support can adopt conventional conditions. The conditions for drying are: drying at 100 °C to 150 °C for 1 to 12 hours. The conditions for calcination are: calcining at 450 °C to 550 °C for 2.5 to 6.0 hours.

[0046] According to the present invention, in the preparation method of the second hydrocracking catalyst described in step (3) and / or the third hydrocracking catalyst described in step (4), the method for loading the hydrogenation component is a conventional method, such as kneading method, impregnation method, etc., and the impregnation method is preferably used. The impregnation method can be saturated impregnation method, excess impregnation method or complex impregnation method, that is, the catalyst carrier is impregnated with a solution containing the required hydrogenation component, and then dried and calcined to obtain a hydrocracking catalyst. The conditions for the drying are: drying at 100°C to 150°C for 1 to 12 hours. The conditions for the calcination are: calcining at 450°C to 550°C for 2.5 to 6.0 hours.

[0047] According to the present invention, in the third hydrocracking product of step (4), the mass ratio of the C6-C8 single-ring cyclic hydrocarbons to the total cyclic hydrocarbon mass in the overhead oil feedstock of the atmospheric column is 0.35 to 0.55, preferably 0.41 to 0.50.

[0048] According to the present invention, the reaction conditions in the third hydrocracking reaction zone of step (4) are as follows: the reaction pressure is 2 to 6 MPa, preferably 3 to 5 MPa.

[0049] According to the present invention, the reaction conditions in the third hydrocracking reaction zone of step (4) are as follows: the average reaction temperature is 250 to 450°C, preferably 300 to 400°C; the liquid hourly space velocity is 0.1 to 15.0 h -1 , preferably 1.0 to 5.0 h -1 ; the hydrogen-oil volume ratio is 100:1 to 2500:1, preferably 400:1 to 2000:1.

[0050] Petroleum hydrocarbons have a complex composition, mainly including paraffins, naphthenes and aromatics, while high-quality ethylene raw materials are small-molecule normal paraffins, and reforming raw materials are single-ring naphthenes and aromatics. The inventors have found through research that the overhead oil feedstock of the atmospheric column can successively undergo shape-selective cracking of straight-chain paraffins, ring-opening cracking of multi-ring cyclic hydrocarbons, and selective hydrocracking of long side chains on isoparaffins or cyclic hydrocarbons to retain single-ring cyclic hydrocarbons as much as possible, and can highly selectively generate small-molecule normal paraffins, thereby realizing the efficient enrichment of small-molecule normal paraffins in low-carbon olefin raw materials, and at the same time retaining single-ring cyclic hydrocarbons in heavy naphtha as much as possible to achieve the efficient enrichment of high-quality reforming raw materials. In this way, the purpose of greatly improving the yields of chemical raw materials (i.e., low-carbon olefin raw materials and reforming raw materials) and the qualities of low-carbon olefin raw materials and reforming raw materials can be achieved, and thus the present invention is completed.

[0051] Compared with the prior art, the present invention has the following beneficial technical effects:

[0052] (1) In the prior art, when hydrogenating and cracking diesel as a raw material to produce chemical raw materials, the final boiling point of the diesel fraction obtained by atmospheric and vacuum distillation is generally 350 - 380 °C. This also results in a relatively high content of tricyclic aromatics in the diesel fraction, and a relatively high reaction pressure is required to achieve the hydrogenation and cracking of tricyclic aromatics. However, a relatively high reaction pressure will also cause some monocyclic aromatics to open-ring and crack during the hydrogenation and cracking process, resulting in the loss of aromatics. In the method for producing more chemical raw materials from crude oil in the present invention, after the crude oil enters the atmospheric column, by controlling the content of tricyclic aromatics in the overhead oil of the atmospheric column to be no higher than 1%, and selecting an appropriate reaction pressure, the mixed processing of monocyclic aromatics and bicyclic aromatics is realized, reducing the loss of aromatics during the hydrogenation process and increasing the content of aromatics in the hydrogenation product. Specifically, the obtained overhead oil raw material of the atmospheric column and hydrogen enter the first hydrocracking reaction zone, mainly selectively cracking the straight-chain paraffins and the long straight chains of isoparaffins and naphthenes containing long straight chains in the raw material to generate small-molecule normal paraffins, so that the content of C7 + normal paraffins in the effluent of the first hydrocracking reaction is 0.1% - 5.0%. The effluent of the first hydrocracking reaction enters the second hydrocracking reaction zone, mainly cracking the polycyclic cyclic hydrocarbons to open the rings and retaining the monocyclic cyclic hydrocarbons and further breaking the side chains in each hydrocarbon to generate small-molecule hydrocarbons. In this way, a large amount of the straight-chain paraffins in the raw material can be converted into gas and light naphtha components, that is, enriched in ethylene raw materials, while the monocyclic cyclic hydrocarbons are retained in the heavy naphtha fraction, that is, enriched in reforming raw materials. Through simple fractionation, the efficient separation of paraffins and cyclic hydrocarbons can be achieved, increasing the production of high-quality ethylene cracking feedstock while improving the quality of heavy naphtha as a catalytic reforming feedstock.

[0053] (2) The content of monocyclic cyclic hydrocarbons in the heavy naphtha obtained by the method of the present invention is high. As the feedstock for the catalytic reforming unit, the alkane cyclization and dehydrogenation unit in the catalytic reforming unit can be cancelled, which can greatly reduce the investment and energy consumption of the catalytic reforming unit; at the same time, since the hydrocracking reaction follows the positive carbon ion reaction mechanism, the side-chain breaking reaction of cyclic hydrocarbons above C9 can be selectively realized, so that the C6 - C8 cyclic hydrocarbons in the product have a relatively high enrichment degree. After catalytic reforming and aromatics extraction, the BTX yield can be greatly increased.

[0054] (3) The present invention selectively converts the straight-chain paraffins in the overhead oil into small-molecule paraffins. This process will consume a certain amount of hydrogen, but the light hydrocarbons also have a high hydrogen yield as the raw material for the ethylene unit. The lower the carbon number, the higher the hydrogen yield. Therefore, most of the hydrogen consumed during the hydrogenation process can be recovered after passing through the ethylene unit. At the same time, the light hydrocarbons as ethylene raw materials can greatly increase the yields of ethylene, propylene and butadiene, and extend the cleaning cycle of the ethylene unit, significantly improving the economic benefits of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 is a process flow schematic diagram of the process method of the present invention;

[0056] Description of main reference numerals:

[0057] 1-crude oil, 2-electric desalting, 3-flash tower, 4-light naphtha, 5-flash tower bottom oil, 6-atmospheric tower, 7-atmospheric tower top oil, 8-atmospheric residue, 9-hydrogen, 10-first hydrocracking reaction zone, 11-first hydrocracking reaction effluent, 12-second hydrocracking reaction zone, 13-second hydrocracking reaction effluent, 14-separator, 15-gas phase stream hydrogen-rich gas, 16-liquid phase stream, 17-fractionation tower, 18-gas fraction, 19-light naphtha, 20-heavy naphtha, 21-tail oil, 22-third hydrocracking reaction zone, 23-third hydrocracking reaction zone effluent. DETAILED DESCRIPTION

[0058] The effects and effects of the present invention are further illustrated below by way of examples, but the following examples do not constitute a limitation of the method of the present invention.

[0059] In the present invention, unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this specification are based on weight, unless the weight basis does not conform to the common understanding of those skilled in the art.

[0060] In the present invention, the total volume space velocity in the examples and comparative examples is the ratio of the volume of fresh feed to the total volume of the catalyst.

[0061] In the present invention, Figure 1 As shown, the process comprises: crude oil 1 enters a flash tower 3 after electro-desalting 2 for separation to obtain light naphtha 4 and flash tower bottom oil 5; the flash tower bottom oil 5 enters an atmospheric tower 6 for separation to obtain atmospheric tower top oil 7 and atmospheric residue 8; the atmospheric tower top oil 7 is mixed with hydrogen 9 and enters a first hydrocracking reaction zone 10 for hydrocracking reaction; the first hydrocracking reaction effluent 11 enters a second hydrocracking reaction zone 12; the second hydrocracking reaction effluent 13 enters a separator 14; the separated gaseous stream hydrogen-rich gas 15 is recycled; the liquid stream 16 enters a fractionation tower 17 for fractionation to obtain a gas fraction 18, light naphtha 19, heavy naphtha 20 and tail oil 21; the tail oil 21 is mixed with hydrogen 7 and enters a third hydrocracking reaction zone 22; the third hydrocracking reaction effluent 23 enters the separator 14 for separation and fractionation.

[0062] In the present invention, the first hydrocracking catalyst in each example is represented by Cat-A plus a number, such as Cat-A1, Cat-A2, Cat-A3, Cat-A4. The first hydrocracking catalyst is prepared by a conventional active metal saturation impregnation method, and the physicochemical properties of the obtained catalyst are shown in Table 1.

[0063] In the present invention, the second hydrocracking catalyst in each example is denoted as Cat-B, and the physical and chemical properties of the catalyst are shown in Table 2.

[0064] In the present invention, the third hydrocracking catalyst in each example is denoted as Cat-C, and the physical and chemical properties of the catalyst are shown in Table 2.

[0065] In the present invention, the second hydrocracking catalyst and the third hydrocracking catalyst in each example are prepared by a conventional active metal saturation impregnation method.

[0066] Among them, the properties of the Beta zeolite used in the catalyst Cat-C are as follows: the molar ratio of SiO2 / Al2O3 is 30, the specific surface area is 350 m 2 / g, and the pore volume is 0.32 cm 3 / g. The properties of the Y zeolite used in the catalyst Cat-B are as follows: the molar ratio of SiO2 / Al2O3 is 15, the specific surface area is 400 m 2 / g, and the pore volume is 0.30 cm 3 / g. The physical and chemical properties of the obtained catalyst are shown in Table 2.

[0067] In the present invention, the feedstock oil in each example uses a crude oil feedstock, and its main properties are shown in Table 3.

[0068] In the present invention, the nitrogen content in the reaction fluid stream in contact with the first hydrocracking catalyst in each example is below 20 mg / kg

[0069] In the present invention, the ethylene feedstock in each example refers to ethane, propane, butane, and light naphtha obtained in step (3). Ethane, propane, butane, and light naphtha can be directly used as feedstocks for steam cracking to produce ethylene.

[0070] In the present invention, the distillation range of light naphtha is the liquid component with a boiling point below 60 °C, and the distillation range of heavy naphtha is 60 - 175 °C.

[0071] In the present invention, the yield of the ethylene feedstock refers to the mass ratio of ethane, propane, butane, and light naphtha in the hydrocracking product to the fresh hydrocracking feedstock (top oil of the atmospheric column), and the yield of heavy naphtha refers to the mass ratio of heavy naphtha in the hydrocracking product to the fresh hydrocracking feedstock (top oil of the atmospheric column).

[0072] Examples 1 - 4

[0073] The method for the crude oil to produce more chemical raw materials adopts the following Figure 1 process, including:

[0074] (1) After the crude oil is desalted by electro - desalting, it enters the flash column to separate the light naphtha fraction, and then enters the atmospheric column to separate the top oil of the atmospheric column and the atmospheric residue.

[0075] (2) The overhead oil from the atmospheric column obtained in step (1) is mixed with hydrogen and enters the first hydrocracking reaction zone; the first hydrocracking reaction zone is filled with the first hydrocracking catalyst; in step (1), the content of C7 + n-alkanes in the effluent from the first hydrocracking reaction is controlled.

[0076] (3) The effluent from the first hydrocracking reaction obtained in step (2) enters the second hydrocracking reaction zone, and the second hydrocracking reaction zone is filled with the second hydrocracking catalyst; a reaction occurs under the action of the catalyst to obtain the second hydrocracking product. The hydrogen-rich gas obtained after the separation and fractionation of the second hydrocracking product is used as recycle hydrogen, and the liquid phase enters the fractionation column for fractionation to obtain gas, light naphtha, heavy naphtha, and tail oil;

[0077] (4) The tail oil from step (3) enters the third hydrocracking reaction zone, and the third hydrocracking reaction zone is filled with the third hydrocracking catalyst; the effluent from the third hydrocracking reaction shares a set of separation and fractionation systems with the effluent from the second hydrocracking reaction.

[0078] The process conditions and hydrocracking effects of each example are shown in Table 5.

[0079] Comparative Example 1

[0080] The difference from Example 1 is that: the overhead oil from the atmospheric column directly enters the second hydrocracking reaction zone, without the first hydrocracking.

[0081] The process conditions and hydrocracking effects in this example are shown in Table 5.

[0082] Comparative Example 2

[0083] The difference from Example 1 is that: in step (1), the mass content of C7 + n-alkanes in the effluent from the first hydrocracking reaction is 6%.

[0084] The process conditions and hydrocracking effects in this example are shown in Table 5.

[0085] Comparative Example 3

[0086] The difference from Example 1 is that: the catalysts in the second and third hydrocracking reaction zones are exchanged. Specifically: the second hydrocracking reaction zone is filled with catalyst Cat-C, and the third hydrocracking reaction zone is filled with catalyst Cat-B.

[0087] The process conditions and hydrocracking effects in this example are shown in Table 5.

[0088] Comparative Example 4

[0089] The difference from Example 1 is that: the reaction pressure in the first hydrocracking reaction zone is the same as the reaction pressure in the third hydrocracking reaction zone.

[0090] In this example, the process conditions and the hydrogenation effect are shown in Table 5.

[0091] Comparative Example 5

[0092] The difference from Example 1 is that the mass content of tricyclic aromatic hydrocarbons in the overhead oil of the atmospheric column is 2.3%.

[0093] In this example, the process conditions and the hydrogenation effect are shown in Table 5.

[0094] Table 1 Physicochemical properties of the first hydrocracking catalyst

[0095]

[0096] Table 2 Physicochemical properties of the second and third hydrocracking catalysts

[0097] Catalyst properties Cat-C Cat-B <![CDATA[Pore volume, cm 3 / g]]> 0.35 0.35 <![CDATA[Specific surface area, m 2 / g]]> 300 300 Catalyst composition and content Beta, wt% 50 - Y, wt% - 30 <![CDATA[MoO3, wt%]]> 10 20 NiO, wt% 5 5 Aluminum oxide, wt% 35 45

[0098] Table 3 Main properties of the feedstock

[0099]

[0100]

[0101] Table 4 Atmospheric distillation process conditions and main properties of the overhead oil of the atmospheric column

[0102] Item Example 1 Example 2 Example 3 Example 4 Top pressure / MPa 0.08 0.08 0.08 0.08 Feed temperature / °C 350 351 353 355 Distillation range / °C (ASTM D86) IBP 59 59 59 59 EBP 290 300 310 320 <![CDATA[C7 + n-alkane, wt%]]> 18.0 17.9 17.6 17.2 Cyclic hydrocarbons, wt% 48.0 48.4 48.7 49.2 Nitrogen content, mg / kg 46 52 60 74 Tricyclic aromatic hydrocarbon content in the overhead oil of the atmospheric column, % 0.2 0.3 0.4 0.6

[0103] Continued Table 4

[0104]

[0105] Table 5 Hydrogenation effect

[0106]

[0107]

[0108] Continued Table 5

[0109]

[0110]

[0111]

[0112] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for producing more chemical raw materials from crude oil, the method comprising: (1) The crude oil is subjected to atmospheric distillation to obtain the overhead oil of the atmospheric column; (2) The overhead oil of the atmospheric column obtained in step (1) is mixed with hydrogen and enters the first hydrocracking reaction zone for the first hydrocracking, and the mass content of C7 + n-alkanes in the first hydrocracking product is controlled to be 0.1% to 5.0%; (3) The reaction effluent from step (2) enters the second hydrocracking reaction zone to selectively open-loop crack the cyclic hydrocarbons with more than two rings to obtain the second hydrocracking product; The hydrogen-rich gas obtained after the gas-liquid separation of the second hydrocracking product through a separator is used as recycle hydrogen, and the liquid phase enters the fractionation system for fractionation to obtain gas, light naphtha, heavy naphtha and tail oil; (4) The tail oil in step (3) is mixed with hydrogen and enters the third hydrocracking reaction zone to obtain a third hydrocracking product containing monocyclic cyclic hydrocarbons, and the third hydrocracking product enters the separation and fractionation system to obtain gas, light naphtha and heavy naphtha; The reaction pressure in the first hydrocracking reaction zone in step (2) is 5-10 MPa; the reaction pressure in the third hydrocracking reaction zone in step (4) is 2-6 MPa; the reaction pressure in the first hydrocracking reaction zone in step (2) is 0.5-5.0 MPa higher than the reaction pressure in the third hydrocracking reaction zone in step (4); The mass content of tricyclic aromatic hydrocarbons in the overhead oil of the atmospheric column is not higher than 1.0%; The first hydrocracking reaction zone is filled with a first hydrocracking catalyst; the first hydrocracking catalyst includes an active metal component and a carrier; the carrier includes a molecular sieve having a selective cracking of normal paraffins, and the molecular sieve is one or more of ZSM-5 molecular sieve, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-35 and ZSM-38 molecular sieves; the active metal component includes at least one of metals in Group VIB and Group VIII; For the first hydrocracking catalyst, based on the weight of the catalyst, the content of the Group VIB metal in terms of oxide is 5.0% - 15.0%, the content of the Group VIII metal in terms of oxide is 2.0% - 5.0%, and the content of the carrier is 80.0% - 93.0%; in the carrier of the first hydrocracking catalyst, based on the weight of the carrier, the content of the molecular sieve is 40% - 92%; The second hydrocracking reaction zone is filled with a second hydrocracking catalyst; the third hydrocracking reaction zone is filled with a third hydrocracking catalyst; The second hydrocracking catalyst and the third hydrocracking catalyst include a cracking component, a hydrogenation component and a binder; the cracking component of the second hydrocracking catalyst in step (3) is Y molecular sieve; the cracking component of the third hydrocracking catalyst in step (4) is Beta molecular sieve; In the second hydrocracking catalyst and the third hydrocracking catalyst, based on the mass of the catalyst, the content of the hydrogenation component in terms of oxide is 5wt% - 40wt%; the content of the cracking component is 10wt% - 80wt%; the content of the binder is 5wt% - 85wt%; The chemical raw materials include ethane, propane, butane, light naphtha and heavy naphtha. Among them, heavy naphtha is used as a reforming raw material to produce BTX, and ethane, propane, butane and light naphtha are used as raw materials for producing low-carbon olefins.

2. The method according to claim 1, wherein In step (2), the reaction pressure in the first hydrocracking reaction zone is 0.5 - 3.0 MPa higher than the reaction pressure in the third hydrocracking reaction zone in step (4).

3. The method according to claim 1, wherein The properties of the crude oil described in step (1) are as follows: the density is 0.80 g / cm 3 ~1.10 g / cm 3 ; the nitrogen mass content is 0.1% - 0.6%; the sulfur mass content is 1% - 6%; the metal content is 10 mg / kg - 100 mg / kg; And / or, the initial boiling point of the overhead oil from the atmospheric column is 50°C - 80°C; the final boiling point is 280°C - 340°C; And / or, the mass content of tricyclic aromatic hydrocarbons in the overhead oil from the atmospheric column is 0.2% - 0.6%.

4. The method according to claim 1, characterized in that, The properties of the crude oil described in step (1) are as follows: the density is 0.85 g / cm 3 ~1.0 g / cm 3 ; the nitrogen mass content is 0.2% - 0.5%; the sulfur mass content is 2% - 4%; the metal content is 20 mg / kg - 60 mg / kg; And / or, the initial boiling point of the overhead oil from the atmospheric column is 60°C - 70°C; the final boiling point is 290°C - 320°C.

5. The method according to claim 1, wherein The atmospheric distillation conditions in step (1) are as follows: the overhead pressure is 0.04 MPa - 0.12 MPa; the feed temperature for atmospheric distillation is 330°C - 390°C.

6. The method according to claim 1, wherein The atmospheric distillation conditions in step (1) are as follows: the overhead pressure is 0.06 MPa - 0.10 MPa; the feed temperature for atmospheric distillation is 350°C - 370°C.

7. The method according to claim 1, characterized in that In step (2), the reaction pressure in the first hydrocracking reaction zone is 6 - 8 MPa.

8. The method according to claim 1, characterized in that, The reaction conditions for the first hydrocracking reaction in step (1) are as follows: the average reaction temperature is 250 to 450 °C; and / or, the liquid hourly space velocity is 0.1 to 15.0 h -1 ; and / or, the hydrogen-oil volume ratio is 100:1 to 2500:

1.

9. The method according to claim 1 or 2, characterized in that, The reaction conditions of the first hydrocracking reaction in step (1) are as follows: the average reaction temperature is 300 to 400 °C; and / or, the liquid hourly space velocity is 1.0 to 5.0 h -1 ; and / or, the hydrogen-oil volume ratio is 400:1 to 2000:

1.

10. The method according to claim 1, wherein In step (3), the reaction pressure in the second hydrocracking reaction zone is 5 - 10 MPa.

11. The method according to claim 1, characterized in that In step (3), the reaction pressure in the second hydrocracking reaction zone is 6 - 8 MPa.

12. The method according to claim 1, characterized in that, In step (3), the reaction conditions in the second hydrocracking reaction zone are as follows: the average reaction temperature is 250~450°C; the liquid hourly space velocity is 0.1~15.0 h -1 ; the hydrogen-oil volume ratio is 100:1~2500:

1.

13. The method according to claim 1, wherein In step (3), the reaction conditions in the second hydrocracking reaction zone are as follows: the average reaction temperature is 300~400°C; the liquid hourly space velocity is 1.0~5.0 h -1 ; the hydrogen-oil volume ratio is 400:1~2000:

1.

14. The method according to claim 1, characterized in that, In step (4), the reaction pressure in the third hydrocracking reaction zone is 3 - 5 MPa.

15. The method according to claim 1, characterized in that In step (4), the reaction conditions in the third hydrocracking reaction zone are as follows: the average reaction temperature is 250~450°C; the liquid hourly space velocity is 0.1~15.0 h -1 ; the hydrogen-oil volume ratio is 100:1~2500:

1.

16. The method according to claim 1, characterized in that, In step (4), the reaction conditions in the third hydrocracking reaction zone are as follows: the average reaction temperature is 300~400°C; the liquid hourly space velocity is 1.0~5.0 h -1 ; the hydrogen-oil volume ratio is 400:1~2000:

1.

17. The method according to claim 1, wherein In step (2), in the first hydrocracking catalyst, the molecular sieve is ZSM-5 molecular sieve; the Group VIB metal is molybdenum and / or tungsten, and the Group VIII metal is cobalt and / or nickel.

18. The method according to claim 1, characterized in that, In the second hydrocracking catalyst in step (3) and / or the third hydrocracking catalyst in step (4), the hydrogenation component is at least one of a metal, a metal oxide, and a metal sulfide of an active metal component; the active metal component includes Group VIB and / or Group VIII metals; the active metal component is at least one of iron, chromium, molybdenum, tungsten, cobalt, and nickel.

19. The method according to claim 1, wherein In the third hydrocracking product of step (4), the ratio of the mass of C6 - C8 monocyclic cyclic hydrocarbons to the total mass of cyclic hydrocarbons in the overhead oil raw material from the atmospheric column is 0.35 - 0.

55.

20. The method according to claim 1, characterized in that In the third hydrocracking product of step (4), the ratio of the mass of C6 - C8 monocyclic cyclic hydrocarbons to the total mass of cyclic hydrocarbons in the overhead oil raw material from the atmospheric column is 0.41 - 0.50.

Images