A processing method for producing more chemical raw materials from crude oil

Abstract

The present invention discloses a processing 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 tower; wherein, the initial boiling point of the overhead oil of the atmospheric tower is 50°C to 80°C, and the final boiling point is 190°C to 240°C; in the presence of hydrogen, the overhead oil of the atmospheric tower enters the first hydrocracking reaction zone to selectively crack the n-alkanes in the overhead oil of the atmospheric tower to obtain the first hydrocracking product; wherein, the mass content of C7 + n-alkanes in the first hydrocracking product is controlled at 0.1% to 5.0%; in the presence of hydrogen, the first hydrocracking product enters the second hydrocracking reaction zone to obtain a second hydrocracking product containing monocyclic cyclic hydrocarbons; the second hydrocracking product is separated and fractionated to obtain a gas fraction, light naphtha, heavy naphtha and tail oil. When using the overhead oil of the atmospheric tower as the raw material to produce chemical raw materials, this method can significantly improve the yield and quality of chemical raw materials.

Description

Technical Field

[0001] The present invention belongs to the field of hydrocracking, and particularly relates to a processing method for producing more chemical raw materials from crude oil, wherein the chemical raw materials are particularly propane, butane, light naphtha, and high-quality heavy naphtha. Background Art

[0002] At present, the rapid growth in the demand for chemical raw materials has become the main driving force for the growth in crude oil demand. Therefore, producing chemical raw materials from crude oil is one of the main means for petroleum refining enterprises to transform and upgrade, improve quality, and increase efficiency. As the source processing unit of modern refineries, the atmospheric and vacuum distillation unit first separates crude oil according to different boiling points, and the obtained products are then subjected to secondary processing. As the most important means for producing chemical raw materials, how to achieve efficient combination with the atmospheric and vacuum distillation unit has become the key for refining enterprises to reduce consumption and increase efficiency.

[0003] Hydrocracking technology has the characteristics of strong feedstock 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 feedstocks for steam cracking of ethylene from tail oil, which are urgently needed in the market. It has become one of the most important hydrocarbon deep processing processes in modern refining and petrochemical industries and has been increasingly widely used in various countries in the world.

[0004] CN201580070326.4 discloses a method for preparing LPG and BTX, including: 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 containing at least C2 and C3 hydrocarbons, an intermediate hydrocarbon stream composed of C4 and / or C5 hydrocarbons, and a heavy hydrocarbon stream containing 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 containing BTX, wherein the second hydrocracking is more severe than the first hydrocracking, d) wherein, in the presence of a C4 hydrocracking catalyst, at least part of the intermediate hydrocarbon stream is subjected to C4 hydrocracking 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 hydrocarbon raw materials, comprising the following steps: (a) feeding the hydrocarbon raw materials into a reaction zone for ring opening; (b) separating the reaction products generated from the reaction zone into an overhead stream and a side stream; (c) feeding the side stream from (b) into a gasoline hydrocracker (GHC) unit; (d) separating the reaction products of the GHC in step (c) into an overhead stream containing hydrogen, methane, ethane and liquefied petroleum gas and a stream containing 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 into a steam cracker unit.

[0006] In summary, petroleum hydrocarbons have a complex composition, mainly including alkanes, cycloalkanes and aromatic hydrocarbons. Among them, alkanes, especially small-molecule alkanes, are high-quality ethylene raw materials, while cycloalkanes and aromatic hydrocarbons 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, 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 processing method for producing more chemical raw materials from crude oil. This method uses the overhead oil of the atmospheric column as the raw material, which can greatly improve the quality and yield of chemical raw materials.

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

[0009] (1) Crude oil is subjected to atmospheric distillation to obtain the overhead oil of the atmospheric column; wherein, the initial boiling point of the overhead oil of the atmospheric column is 50°C to 80°C, and the final boiling point is 190°C to 240°C;

[0010] (2) In the presence of hydrogen, the overhead oil of the atmospheric column enters the first hydrocracking reaction zone to selectively crack the normal paraffins in the overhead oil of the atmospheric column to obtain the first hydrocracking product; wherein, the mass content of C7 normal paraffins in the first hydrocracking product is controlled at 0.1% to 5.0%; +

[0011] (3) In the presence of hydrogen, the first hydrocracking product enters the second hydrocracking reaction zone to obtain a second hydrocracking product containing monocyclic cyclic hydrocarbons;

[0012] (4) The second hydrocracking product is separated and fractionated to obtain a gas fraction, light naphtha, heavy naphtha and tail oil.

[0013] According to the present invention, preferably, in step (2), the mass content of C7 n-alkanes in the first hydrocracking product + is controlled to be 1.0% to 4.0%.

[0014] According to the present invention, in the second hydrocracking product in step (3), the ratio of the mass of C6-C8 monocyclic cyclic hydrocarbons to the total mass of cyclic hydrocarbons in the atmospheric tower top oil feedstock is 0.40 to 0.80, preferably 0.46 to 0.60.

[0015] According to the present invention, in step (2), the first hydrocracking reaction zone is filled with a first hydrocracking catalyst, and in step (3), the second hydrocracking reaction zone is filled with a second hydrocracking catalyst. Among them, the first hydrocracking catalyst can be one or more catalysts, and the second hydrocracking catalyst can be one or more catalysts.

[0016] According to the present invention, the tail oil obtained in step (4) can be recycled to the first hydrocracking reaction zone in step (2), and / or recycled to the second hydrocracking reaction zone in step (3).

[0017] According to the present invention, the chemical raw materials mainly include ethane, propane, butane, 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, they are used as steam cracking raw materials to produce ethylene, 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.

[0018] 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 to 1.10 g / cm 3 , preferably 0.85 g / cm 3 to 1.0 g / cm 3 ; the nitrogen mass content is 0.1% to 0.6%, preferably 0.2% to 0.5%; the sulfur mass content is 1% to 6%, preferably 2% to 4%; the metal content is 10 mg / kg to 100 mg / kg, preferably 20 mg / kg to 60 mg / kg.

[0019] According to the present invention, preferably, the initial boiling point of the atmospheric tower top oil in step (2) is 60 °C to 70 °C, and the final boiling point is 200 °C to 220 °C.

[0020] According to the present invention, preferably, the mass content of bicyclic aromatic hydrocarbons in the atmospheric tower top oil is 0.1% to 1.0%, preferably 0.2% to 0.6%.

[0021] According to the present invention, the atmospheric distillation conditions in step (1) are as follows: the top pressure of the column is 0.04 MPa to 0.12 MPa, preferably 0.06 MPa to 0.10 MPa; the feed temperature for atmospheric distillation is 330 °C to 390 °C, preferably 350 °C to 370 °C.

[0022] According to the present invention, in the raw material of the overhead oil from the atmospheric column, the mass content of C7 + n - paraffin is 6% to 60%, preferably 10% to 40%; the mass content of cyclic hydrocarbons is 30% to 80%, and the cyclic hydrocarbons are the sum of naphthenes and aromatics.

[0023] According to the present invention, a hydrofining catalyst can be arranged 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.

[0024] According to the present invention, the hydrofining catalyst described above can adopt a conventional hydrofining catalyst, which is mainly used for hydrodesulfurization, denitrification and other impurities. The hydrofining catalyst includes a carrier and a hydrogenation active metal. 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%; 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 5.0%.

[0025] 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 with selective cracking of n - 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, and more preferably ZSM - 5 molecular sieve. The SiO2 / Al2O3 molar ratio of the ZSM - 5 molecular sieve is 20 to 60. The carrier may also include a binder. Preferably, the binder is alumina. The active metal component includes at least one of Group VIB and Group VIII metals. The Group VIB metal is preferably molybdenum and / or tungsten, and the Group VIII metal is preferably cobalt and / or nickel.

[0026] According to the present invention, in step (2), preferably, in the first hydrocracking catalyst, based on the weight of the catalyst, the content of Group VIB metal (calculated as oxide) is 5.0% to 15.0%, the content of Group VIII metal (calculated as oxide) is 2.0% to 5.0%, and the content of the carrier is 80.0% to 93.0%.

[0027] 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%.

[0028] According to the present invention, in step (2), the specific surface area of the first hydrocracking catalyst is 200 to 400 m 2 / g, and the pore volume is 0.25 to 0.45 mL / g.

[0029] According to the present invention, in step (2), the preparation method of the first hydrocracking catalyst can be prepared according to the conventional methods in the art. The preparation method includes the preparation of the carrier and the loading of the active metal components. The process of preparing the carrier is as follows: the shape-selective cracking molecular sieve and the binder are mechanically mixed, formed, and then dried and calcined to make the catalyst carrier. The drying and calcining of the carrier can adopt conventional conditions. The conditions for drying are: drying at 100°C to 150°C for 1 to 12 hours. The conditions for calcining are: calcining at 450°C to 550°C for 2.5 to 6.0 hours.

[0030] 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 carrier 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 calcining are: calcining at 450°C to 550°C for 2.5 to 6.0 hours.

[0031] According to the present invention, in step (3), the second hydrocracking catalyst has the function of selectively cracking the side chains of isoparaffins or cyclic hydrocarbons and retaining the monocyclic cyclic hydrocarbons. The second hydrocracking catalyst includes a cracking component, a hydrogenation component, and a binder. The second hydrocracking catalyst can be a commercially available product 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. In the second hydrocracking catalyst, 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, and more preferably Beta zeolite.

[0032] According to the present invention, in step (3), for the second hydrocracking catalyst, based on the weight of the second hydrocracking catalyst, the content of the hydrogenation component in terms of oxide is 5 wt% to 40 wt%, preferably 10 wt% to 20 wt%; the content of the cracking component is 20 wt% to 80 wt%, preferably 30 wt% to 70 wt%; the content of the binder is 5 wt% to 75 wt%, preferably 10 wt% to 50 wt%.

[0033] According to the present invention, in step (3), the preparation method of the second hydrocracking catalyst can be prepared according to the conventional methods in the art. The preparation method includes the preparation of a carrier and the loading of a hydrogenation component, and the process of preparing the carrier is as follows: mechanically mixing the cracking component and the binder, shaping, and then drying and calcining to make a catalyst carrier. The drying and calcining of the carrier can adopt conventional conditions. The conditions for drying are: drying at 100°C to 150°C for 1 to 12 hours. The conditions for calcining are: calcining at 450°C to 550°C for 2.5 to 6.0 hours.

[0034] According to the present invention, in step (3), in the preparation method of the second hydrocracking catalyst, the method for loading the hydrogenation component 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, impregnating the catalyst carrier with a solution containing the required hydrogenation component, and then drying and calcining to obtain the second hydrocracking catalyst. The conditions for drying are: drying at 100°C to 150°C for 1 to 12 hours. The conditions for calcining are: calcining at 450°C to 550°C for 2.5 to 6.0 hours.

[0035] According to the present invention, in step (2), the reaction conditions for the first hydrocracking reaction are as follows: the reaction pressure is 1.0 to 5.0 MPa, preferably 2.0 to 4.0 MPa.

[0036] According to the present invention, the reaction conditions of the first hydrocracking reaction in step (2) 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.

[0037] According to the present invention, the reaction conditions of the second hydrocracking reaction in step (3) are as follows: the reaction pressure is 1.0 to 5.0 MPa, preferably 2.0 to 4.0 MPa.

[0038] According to the present invention, the reaction conditions of the second hydrocracking reaction in step (3) 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.

[0039] According to the present invention, preferably, the first hydrocracking reaction zone and the second hydrocracking reaction zone adopt the same pressure.

[0040] According to the present invention, preferably, the second hydrocracking product in step (3) is subjected to supplementary hydrofining. The supplementary hydrofining can be carried out by loading a hydrofining catalyst at the bottom of the second hydrocracking reaction zone, or it can enter a separate hydrofining reaction zone.

[0041] According to the present invention, preferably, the second hydrocracking product in step (3) can also first enter the fractionation system, and the separated heavy naphtha component is subjected to supplementary hydrofining.

[0042] According to the present invention, in step (4), the heavy naphtha and the tail oil can be sent out of the unit, or the tail oil can be recycled to step (3).

[0043] Petroleum hydrocarbons have a complex composition, mainly including alkanes, cycloalkanes and aromatics. High-quality ethylene raw materials are small-molecule normal alkanes, and reforming raw materials are monocyclic cycloalkanes and aromatics. The inventors have found through research that the overhead oil raw material of the atmospheric tower can pass through the shape-selective cracking of straight-chain alkanes and the selective hydrocracking of long side chains on isoparaffins or cyclic hydrocarbons in sequence to retain monocyclic cyclic hydrocarbons as much as possible, and can highly selectively generate small-molecule normal alkanes, so as to realize the efficient enrichment of small-molecule normal alkanes in the light olefin raw materials, and at the same time retain monocyclic cyclic hydrocarbons in the heavy naphtha as much as possible to realize 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., light olefin raw materials and reforming raw materials) and the qualities of light olefin raw materials and reforming raw materials can be achieved, and thus the present invention is completed.

[0044] Compared with the prior art, the present invention has the following beneficial technical effects:

[0045] (1) Reforming belongs to cyclization dehydrogenation reaction, which will not change the carbon number of hydrocarbons with different molecular structures in the raw material. Generally, by controlling the carbon number distribution of hydrocarbons in the raw material, the C9 + aromatic hydrocarbon yield in the reformed product oil is reduced, and the generation of low-value-added products is reduced. In the prior art, when producing catalytic reforming raw materials, in order to reduce the C9 + content of cyclic hydrocarbons, the final boiling point of heavy naphtha obtained by atmospheric distillation is usually controlled not to be higher than 180 °C. In the processing method for producing more chemical raw materials from crude oil of the present invention, by controlling the mass content of bicyclic aromatic hydrocarbons in the overhead oil of the atmospheric column to be not higher than 1%, the C9 + content of cyclic hydrocarbons is increased, especially the C9 + content of monocyclic cyclic hydrocarbons, while preventing bicyclic aromatic hydrocarbons with higher hydrogenation difficulty from entering the raw material. Then, through hydrocracking, C9 + cyclic hydrocarbons are converted into C6-C9 cyclic hydrocarbons, the final boiling point of the reforming raw material is increased, and the distillation range of the reforming raw material is broadened; as is well known, with the increase of the distillation range in crude oil, the content of cyclic hydrocarbons also increases. Increasing the final boiling point of the reforming raw material can not only increase the source of reforming raw materials, but also increase the yield of C6-C9 light aromatic hydrocarbons in the catalytic reforming unit, thereby greatly improving the efficiency of the reforming unit.

[0046] (2) In the processing method for producing more chemical raw materials from crude oil of the present invention, the overhead oil of the atmospheric column and hydrogen enter the first hydrocracking reaction zone, mainly to selectively crack the n-alkanes in the raw material and the long straight chains of isoalkanes and cycloalkanes containing long straight chains to generate small molecule n-alkanes, so that the content of C7 + n-alkanes in the first hydrocracking product is below 5%. The first hydrocracking product enters the second hydrocracking reaction zone, mainly to selectively crack the iso-side chains on the isoalkanes and cyclic hydrocarbons and retain the monocyclic cyclic hydrocarbons. In this way, a large amount of chain alkanes in the raw material can be converted into gas and light naphtha components, that is, enriched in the raw material of the ethylene plant, while the monocyclic cyclic hydrocarbons are retained in the heavy naphtha fraction, that is, enriched in the reforming raw material. 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 catalytic reforming feedstock.

[0047] (3) 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 carbocation reaction mechanism, the side-chain breaking reaction of cyclic hydrocarbons with more than C9 can be selectively achieved, so that the C6-C8 cyclic hydrocarbons in the product have a higher enrichment degree, and the BTX yield can be greatly increased after catalytic reforming and aromatics extraction.

[0048] (4) The method of the present invention selectively converts the alkanes in the overhead oil of the atmospheric tower into small-molecule alkanes. This process consumes a certain amount of hydrogen, but the light hydrocarbons also have a high hydrogen yield as the feedstock for the ethylene unit. The lower the carbon number, the higher the hydrogen yield. Therefore, most of the hydrogen consumed in the hydrogenation process can be recovered after passing through the ethylene unit. At the same time, the light hydrocarbons as the ethylene feedstock 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

[0049] Figure 1 is a schematic process flow diagram of the process method of the present invention;

[0050] MAIN REFERENCE NUMERALS DESCRIPTION:

[0051] 1 - Crude oil, 2 - Electrostatic desalting, 3 - Flash distillation tower, 4 - Light naphtha, 5 - Bottom oil of flash distillation tower, 6 - Atmospheric tower, 7 - Overhead oil of atmospheric tower, 8 - Diesel oil, 9 - Atmospheric residue, 10 - Hydrogen, 11 - First hydrocracking reaction zone, 12 - Effluent of first hydrocracking reaction, 13 - Second hydrocracking reaction zone, 14 - Effluent of second hydrocracking reaction, 15 - Separator, 16 - Hydrogen-rich gas in gas-phase stream, 17 - Liquid-phase stream, 18 - Fractionating tower, 19 - Gas fraction, 20 - Light naphtha, 21 - Heavy naphtha, 22 - Tail oil. DETAILED DESCRIPTION OF THE INVENTION

[0052] The functions and effects of the present invention will be further described below through examples, but the following examples do not limit the method of the present invention.

[0053] In the present invention, % is the mass fraction unless otherwise specified.

[0054] The overall volume space velocity in the examples and comparative examples is the ratio of the fresh feed volume to the total volume of the catalyst.

[0055] The method of the present invention, as Figure 1As shown in the figure, it includes: The crude oil 1 enters the flash tower 3 after electro - desalting 2 and is separated to obtain light naphtha 4 and the bottom oil 5 of the flash tower. The bottom oil 5 of the flash tower enters the atmospheric tower 6 and is separated to obtain the overhead oil 7 of the atmospheric tower, diesel 8 and atmospheric residue 9. The overhead oil 7 of the atmospheric tower is mixed with hydrogen 10 and enters the first hydrocracking reaction zone 11 for the first hydrocracking reaction. The effluent 12 from the first hydrocracking reaction enters the second hydrocracking reaction zone 13 for the second hydrocracking reaction. The effluent 14 from the second hydrocracking reaction enters the separator 15. The hydrogen - rich gas 16 separated from the gas - phase stream is recycled, and the liquid - phase stream 17 enters the fractionating tower 18, and is fractionated to obtain gas fraction 19, light naphtha 20, heavy naphtha 21 and tail oil 22. The tail oil 22 is recycled to the upstream of the reaction stream in the second hydrocracking reaction zone 13.

[0056] 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. The first hydrocracking catalyst is prepared by the conventional active metal saturation impregnation method, and the physicochemical properties of the obtained catalyst are shown in Table 1.

[0057] In the present invention, the second hydrocracking catalyst in each example is represented by Cat - B plus a number, such as Cat - B1, Cat - B2. The physicochemical properties of the catalyst are shown in Table 2. The second hydrocracking catalyst in each example is prepared by the conventional active metal saturation impregnation method. Among them, the properties of the Beta zeolite used in Cat - B1 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 Cat - B2 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 physicochemical properties of the obtained catalyst are shown in Table 2.

[0058] In the present invention, the main properties of the crude oil used in each example are shown in Table 3.

[0059] In the present invention, the nitrogen content in the reaction stream in contact with the first hydrocracking catalyst in each example is below 20 mg / kg.

[0060] In the present invention, the ethylene raw materials in each example refer to ethane, propane, butane and light naphtha obtained in step (3). Ethane, propane, butane and light naphtha can be directly used as raw materials for steam cracking to produce ethylene.

[0061] In the present invention, the distillation range of light naphtha is the liquid component with a boiling point less than 60 °C, the distillation range of heavy naphtha is 60 - 175 °C, and the distillation range of tail oil is the component with a boiling point > 175 °C.

[0062] In the present invention, the yield of ethylene raw materials refers to the mass ratio of ethane, propane, butane, and light naphtha in the hydrocracking product to the fresh hydrocracking raw materials (the 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 raw materials (the top oil of the atmospheric column).

[0063] Example 1

[0064] The method of this example adopts the process as shown in Figure 1 The process includes:

[0065] (1) After the crude oil is desalted by electro-de-salting, 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, the side-draw oil of the atmospheric column, and the atmospheric residue;

[0066] (2) The top oil of the atmospheric column is mixed with hydrogen and successively enters the first hydrocracking reaction zone and the second hydrocracking reaction zone; the first hydrocracking reaction zone is filled with the shape-selective cracking catalyst Cat-A1; the second hydrocracking reaction zone is filled with the hydrocracking catalyst Cat-B1; in step (2), the content of C7 normal paraffins in the effluent of the first hydrocracking reaction is controlled to be 1%. + The content of normal paraffins is 1%.

[0067] (3) The effluent of the second hydrocracking reaction zone in step (2) is separated into a gas-phase stream and a liquid-phase stream by gas-liquid separation. The gas-phase stream is recycled, and the liquid-phase stream enters the fractionating column to fractionate into a gas fraction, light naphtha, heavy naphtha, and tail oil. The tail oil is recycled to the inlet of the second hydrocracking reaction zone.

[0068] The process conditions and hydrocracking effects in this example are shown in Table 5.

[0069] Example 2

[0070] The method of this example adopts the process as shown in Figure 1 The process includes:

[0071] (1) After the crude oil is desalted by electro-de-salting, 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, the side-draw oil of the atmospheric column, and the atmospheric residue;

[0072] (2) The top oil of the atmospheric column is mixed with hydrogen and successively enters the first hydrocracking reaction zone and the second hydrocracking reaction zone; the first hydrocracking reaction zone is filled with the shape-selective cracking catalyst Cat-A2; the second hydrocracking reaction zone is filled with the hydrocracking catalyst Cat-B2; in step (2), the content of C7 normal paraffins in the effluent of the first hydrocracking reaction is controlled to be 2%. + The content of normal paraffins is 2%.

[0073] (3) In step (2), the reaction effluent from the second hydrocracking reaction zone is separated into a gas-phase stream and a liquid-phase stream. The gas-phase stream is recycled, and the liquid-phase stream enters the fractionating column, where gas fractions, light naphtha, heavy naphtha, and tail oil are fractionated. The tail oil is recycled to the inlet of the second hydrocracking reaction zone.

[0074] In this example, the process conditions and the hydrotreating effect are shown in Table 5.

[0075] Example 3

[0076] The method of this example uses the following Figure 1 process, including:

[0077] (1) After being electro-de-salted, the crude oil enters the flash column to separate the light naphtha fraction, and then enters the atmospheric column to separate the overhead oil of the atmospheric column, the side-draw oil of the atmospheric column, and the atmospheric residue.

[0078] (2) The overhead oil of the atmospheric column is mixed with hydrogen and successively enters the first hydrocracking reaction zone and the second hydrocracking reaction zone. The first hydrocracking reaction zone is filled with the shape-selective cracking catalyst Cat-A3; the second hydrocracking reaction zone is filled with the hydrocracking catalyst Cat-B1; in step (2), the content of C7 + n-paraffins in the reaction effluent from the first hydrocracking reaction is controlled to be 4%.

[0079] (3) In step (2), the reaction effluent from the second hydrocracking reaction zone is separated into a gas-phase stream and a liquid-phase stream. The gas-phase stream is recycled, and the liquid-phase stream enters the fractionating column, where gas fractions, light naphtha, heavy naphtha, and tail oil are fractionated. The tail oil is recycled to the inlet of the second hydrocracking reaction zone.

[0080] In this example, the process conditions and the hydrotreating effect are shown in Table 5.

[0081] Example 4

[0082] The first hydrocracking reaction zone is filled with the same first hydrocracking catalyst Cat-A1 as in Example 1.

[0083] The second hydrocracking reaction zone is filled with the second hydrocracking catalyst Cat-B2.

[0084] The method of this example uses the following Figure 1 process, including:

[0085] (1) After being electro-de-salted, the crude oil enters the flash column to separate the light naphtha fraction, and then enters the atmospheric column to separate the overhead oil of the atmospheric column, the side-draw oil of the atmospheric column, and the atmospheric residue.

[0086] (2) The overhead oil from the atmospheric column is mixed with hydrogen and successively enters the first hydrocracking reaction zone and the second hydrocracking reaction zone; the first hydrocracking reaction zone is filled with a shape-selective cracking catalyst Cat-A1; the second hydrocracking reaction zone is filled with a hydrocracking catalyst Cat-B2; in step (2), the content of C7 + n-paraffins in the effluent from the first hydrocracking reaction is controlled to be 1%.

[0087] (3) The effluent from the second hydrocracking reaction zone in step (2) is separated into a gas-phase stream and a liquid-phase stream by gas-liquid separation. The gas-phase stream is recycled, and the liquid-phase stream enters the fractionating column, where gas fractions, light naphtha, heavy naphtha, and tail oil are fractionated. The tail oil is recycled to the inlet of the second hydrocracking reaction zone.

[0088] In this example, the process conditions and the hydrocracking effect are shown in Table 5.

[0089] Comparative Example 1

[0090] The difference from Example 1 is that the overhead oil from the atmospheric column directly enters the second hydrocracking reaction zone and reacts with the Cat-B1 catalyst.

[0091] In this example, the process conditions and the hydrocracking effect are shown in Table 5.

[0092] Comparative Example 2

[0093] The difference from Example 1 is that in step (2), the content of C7 + n-alkanes in the product of the first hydrocracking reaction is controlled to be 6%.

[0094] In this example, the process conditions and the hydrocracking effect are shown in Table 5.

[0095] Comparative Example 3

[0096] The difference from Example 3 is that the first hydrocracking reaction zone is filled with the catalyst Cat-B2.

[0097] In this example, the process conditions and the hydrocracking effect are shown in Table 5.

[0098] Comparative Example 4

[0099] The difference from Example 1 is that the mass content of bicyclic aromatic hydrocarbons in the overhead oil from the atmospheric column is 2.0%. In this example, the process conditions and the hydrocracking effect are shown in Table 5.

[0100] Table 1 Physicochemical properties of the first hydrocracking catalyst

[0101]

[0102] Table 2 Physicochemical properties of the second hydrocracking catalyst

[0103] Catalyst properties Cat-B1 Cat-B2 <![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% - 50 <![CDATA[MoO3, wt%]]> 10 10 NiO, wt% 5 5 Aluminum oxide, wt% 35 35

[0104] Table 3 Main properties of raw materials

[0105]

[0106]

[0107] Table 4 Atmospheric distillation process conditions and main properties of overhead oil from atmospheric column

[0108] 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 200 206 213 220 <![CDATA[C7 + n - paraffin, wt%]]> 18.0 17.8 17.7 17.5 Cyclic hydrocarbons, wt% 48.0 48.3 48.7 49.2 Nitrogen content, mg / kg 3.4 3.8 4.1 4.7 Amount of bicyclic aromatic hydrocarbons in the overhead oil of the atmospheric column, % 0.2 0.3 0.4 0.6

[0109] Continued Table 4

[0110] Item Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Top pressure / MPa 0.08 0.08 0.08 0.08 Feed temperature / °C 350 350 350 365 Distillation range / °C (ASTM D86) IBP 59 59 59 59 EBP 200 200 200 250 <![CDATA[C7 + n - paraffin, wt%]]> 18.0 18.0 18.0 17.1 Cyclic hydrocarbons, wt% 48.0 48.0 48.0 51.6 Nitrogen content, mg / kg 3.4 3.4 3.4 6.3 Amount of bicyclic aromatic hydrocarbons in the overhead oil of the atmospheric column, % 0.2 0.2 0.2 2.0

[0111] Table 5 Hydrogenation effect

[0112]

[0113]

[0114] Continued Table 5

[0115]

[0116] 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 processing 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; wherein, the initial boiling point of the overhead oil of the atmospheric column is 50°C to 80°C, and the final boiling point is 190°C to 240°C; (2) In the presence of hydrogen, the overhead oil of the atmospheric tower enters the first hydrocracking reaction zone to selectively crack the n-alkanes in the overhead oil of the atmospheric tower, obtaining a first hydrocracking product; wherein, the mass content of C7 + n-alkanes in the first hydrocracking product is controlled to be 0.1% to 5.0%; (3) In the presence of hydrogen, the first hydrocracking product enters the second hydrocracking reaction zone to obtain a second hydrocracking product containing monocyclic cyclic hydrocarbons; (4) The second hydrocracking product is separated and fractionated to obtain a gas fraction, light naphtha, heavy naphtha and tail oil; The mass content of bicyclic aromatic hydrocarbons in the overhead oil of the atmospheric column is 0.1% to 1.0%; The first hydrocracking reaction zone is filled with a first hydrocracking catalyst, and the second hydrocracking reaction zone is filled with a second hydrocracking catalyst; In step (2), the first hydrocracking catalyst includes an active metal component and a support; the support includes a molecular sieve having selective cracking of normal paraffins, and the molecular sieve is 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; the active metal component includes at least one of Group VIB metals and Group VIII metals; In step (2), 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% to 15.0%, the content of the Group VIII metal in terms of oxide is 2.0% to 5.0%, and the content of the support is 80.0% to 93.0%; in the support of the first hydrocracking catalyst, based on the weight of the support, the content of the binder is 8% to 60%, and the content of the molecular sieve is 40% to 92%; In step (3), the second hydrocracking catalyst includes a cracking component, a hydrogenation component and a binder; the cracking component includes at least one of Beta molecular sieve and Y molecular sieve; In step (3), for the second hydrocracking catalyst, based on the weight of the second hydrocracking catalyst, the content of the hydrogenation component in terms of oxide is 5wt% to 40wt%; the content of the cracking component is 20wt% to 80wt%; the content of the binder is 5wt% to 75wt%; In step (3), the second hydrocracking catalyst has the function of selectively cracking the side chains of isoparaffins or cyclic hydrocarbons and retaining monocyclic cyclic hydrocarbons; The chemical raw materials include ethane, propane, butane, light naphtha and heavy naphtha, wherein, the 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, characterized in that, The tail oil obtained in step (4) is recycled to the first hydrocracking reaction zone of step (2), and / or recycled to the second hydrocracking reaction zone of step (3).

3. The method according to claim 1, wherein The properties of the crude oil 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.

4. The method according to claim 1, characterized in that, The properties of the crude oil 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.

5. The method according to claim 1, wherein The initial boiling point of the overhead oil of the atmospheric column is 60°C to 70°C, and the final boiling point is 200°C to 220°C; and / or, the mass content of bicyclic aromatic hydrocarbons in the overhead oil of the atmospheric column is 0.2% to 0.6%.

6. The method according to claim 1, characterized in that, The atmospheric distillation conditions are as follows: the top pressure is 0.04MPa to 0.12MPa; the atmospheric distillation feed temperature is 330°C to 390°C.

7. The method according to claim 1, wherein The atmospheric distillation conditions are as follows: the top pressure is 0.06 MPa to 0.10 MPa; the feed temperature for atmospheric distillation is 350 °C to 370 °C.

8. The method according to claim 1, wherein The nitrogen content in the reaction stream in contact with the hydrocracking catalyst loaded in the first hydrocracking reaction zone is below 50 mg / kg.

9. The method according to claim 1, characterized in that, The nitrogen content in the reaction stream in contact with the hydrocracking catalyst loaded in the first hydrocracking reaction zone is below 20 mg / kg.

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

11. The method according to claim 1, characterized in that, In step (3), for the second hydrocracking catalyst, based on the weight of the second hydrocracking catalyst, the content of the hydrogenation component in terms of oxide is 10 wt% to 20 wt%; the content of the cracking component is 30 wt% to 70 wt%; the content of the binder is 10 wt% to 50 wt%.

12. The method according to claim 1, wherein In step (2), the reaction conditions for the first hydrocracking reaction are as follows: The reaction pressure is 1.0 to 5.0 MPa; The average reaction temperature is 250 to 450 °C; The hourly space velocity of the liquid is 0.1~15.0 h -1 ; The hydrogen-oil volume ratio is 100:1 to 2500:

1.

13. The method according to claim 1, characterized in that In step (2), the reaction conditions for the first hydrocracking reaction are as follows: The reaction pressure is 2.0 to 4.0 MPa; The average reaction temperature is 300 to 400 °C; The hourly space velocity of the liquid is 1.0 to 5.0 h -1 ; The hydrogen-oil volume ratio is 400:1 to 2000:

1.

14. The method according to claim 1, characterized in that, In step (3), the reaction conditions for the second hydrocracking reaction are as follows: The reaction pressure is 1.0 to 5.0 MPa; The average reaction temperature is 250 to 450 °C; The hourly space velocity of the liquid is 0.1~15.0 h -1 ; The hydrogen-oil volume ratio is 100:1 to 2500:

1.

15. The method according to claim 1, wherein In step (3), the reaction conditions for the second hydrocracking reaction are as follows: The reaction pressure is 2.0 to 4.0 MPa; The average reaction temperature is 300 to 400 °C; The hourly space velocity of the liquid is 1.0~5.0 h -1 ; The hydrogen-oil volume ratio is 400:1 to 2000:

1.

16. The method according to claim 1, characterized in that, The ratio of the mass of C6-C8 monocyclic cyclic hydrocarbons in the second hydrocracking product described in step (3) to the total mass of cyclic hydrocarbons in the atmospheric tower top oil feedstock is 0.40 to 0.

80.

17. The method according to claim 1, characterized in that The ratio of the mass of C6-C8 monocyclic cyclic hydrocarbons in the second hydrocracking product described in step (3) to the total mass of cyclic hydrocarbons in the atmospheric tower top oil feedstock is 0.46 to 0.60.

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