A method for producing chemical raw materials from crude oil

Abstract

The present invention discloses a method for producing chemical raw materials from crude oil. The method includes: after the crude oil is subjected to electro-desalting, it enters a flash tower to separate out the light naphtha fraction, and then enters an atmospheric tower to separate out the overhead oil of the atmospheric tower; wherein, the mass content of bicyclic aromatic hydrocarbons in the overhead oil of the atmospheric tower is not higher than 1.0%; in the presence of hydrogen, the overhead oil of the atmospheric tower is contacted with a shape-selective cracking catalyst for shape-selective cracking reaction; wherein the mass content of C7 + n-alkanes in the effluent of the shape-selective cracking reaction is controlled at 0.1% to 5.0%; the effluent of the shape-selective cracking reaction is separated and fractionated to obtain a gas fraction, light naphtha, heavy naphtha and tail oil; the tail oil is contacted with an isohydrocarbon conversion catalyst for isohydrocarbon conversion reaction, and after separation and fractionation, a gas fraction, light naphtha and heavy naphtha are obtained; the pressure of the isohydrocarbon conversion reaction is 0.5 MPa to 2.0 MPa lower than the pressure of the shape-selective cracking reaction. This method can greatly improve the quality and yield of chemical products.

Description

Technical Field

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

[0002] Nowadays, the demand for chemical raw materials has been maintaining a relatively high growth rate and has gradually become a major driving force for the growth of 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 an efficient combination with the atmospheric and vacuum distillation unit has become the key for refining enterprises to reduce consumption and increase efficiency.

[0003] 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 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.

[0004] CN201480037272.7 discloses a method for producing light olefin hydrocarbon compounds from a hydrocarbon raw material, comprising the following steps: (a) feeding the hydrocarbon raw material 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 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 to a steam cracker unit.

[0005] In summary, in the prior art, for the conversion of crude oil, it is impossible to achieve the mixed processing of different fractions, nor can the paraffins (including long side chains on cyclic hydrocarbons) be selectively and efficiently enriched into ethylene raw materials, and the cyclic hydrocarbons be enriched into reforming raw materials. Therefore, in view of the above problems, it is of great significance to develop an excellent processing method for producing chemical raw materials. Summary of the Invention

[0006] Aiming at the problems existing in the prior art, the object of the present invention is to provide a method for producing chemical raw materials from crude oil. This method uses the overhead oil of the atmospheric column as the raw material, which can significantly improve the quality and yield of chemical products.

[0007] The present invention provides a method for producing chemical raw materials from crude oil, and the method includes:

[0008] (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 obtain the overhead oil of the atmospheric column; wherein, the mass content of bicyclic aromatic hydrocarbons in the overhead oil of the atmospheric column is not higher than 1%.

[0009] (2) In the presence of hydrogen, the overhead oil of the atmospheric column in step (1) is contacted with a shape-selective cracking catalyst for shape-selective cracking reaction; wherein the mass content of C7 + n-alkanes in the effluent of the shape-selective cracking reaction is controlled to be 0.1% to 5.0%.

[0010] (3) The effluent of the shape-selective cracking reaction in step (2) is separated and fractionated to obtain a gas fraction, light naphtha, heavy naphtha and tail oil.

[0011] (4) In the presence of hydrogen, the tail oil in step (3) is contacted with an isohydrocarbon conversion catalyst for isohydrocarbon conversion reaction, and after separation and fractionation, a gas fraction, light naphtha and heavy naphtha are obtained.

[0012] The reaction pressure of the isohydrocarbon conversion reaction is 0.5 MPa to 2.0 MPa lower than the reaction pressure of the shape-selective cracking reaction.

[0013] 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.

[0014] According to the present invention, the initial boiling point of the overhead oil of the atmospheric column in step (1) is 50°C to 80°C, preferably 60°C to 70°C; the final boiling point is 190°C to 260°C, preferably 200°C to 220°C.

[0015] According to the present invention, the atmospheric distillation conditions in step (1) are as follows: the overhead pressure 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.

[0016] According to the present invention, preferably, the mass content of bicyclic aromatic hydrocarbons in the overhead oil of the atmospheric column is 0.2% to 0.6%.

[0017] According to the present invention, the chemical raw materials include light olefin raw materials and reforming raw materials. Specifically, 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 light 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, light olefins refer to olefins with four or fewer carbon atoms, especially ethylene, propylene, and butadiene.

[0018] According to the present invention, in step (2), the shape-selective cracking catalyst can be one or more catalysts.

[0019] According to the present invention, the composition of the shape-selective cracking catalyst in step (2), based on the mass of the catalyst, includes:

[0020] a) 55% to 72% of molecular sieve; 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, preferably ZSM-5 molecular sieve;

[0021] b) 3% to 18% of at least one metal selected from Group VIB and Group VIII metals, calculated as oxides;

[0022] c) 1% to 13% of binder;

[0023] d) 8% to 37% of macroporous alumina.

[0024] According to the present invention, preferably, component a) is ZSM-5 molecular sieve. Preferably, the SiO2 / Al2O3 molar ratio of the ZSM-5 molecular sieve is 40 to 60.

[0025] According to the present invention, preferably, the Group VIB metal in component b) is molybdenum and / or tungsten. The Group VIII metal in component b) is cobalt and / or nickel.

[0026] According to the present invention, preferably, the binder in component c) can be a conventional binder; such as one or more of alumina, silica, titanium oxide, etc., and preferably small-pore alumina is used. The properties of the small-pore alumina are as follows: the specific surface area is 240-300 m 2 / g, the pore volume is 0.3-0.5 mL / g, and the average pore diameter is 3-6 nm.

[0027] According to the present invention, preferably, the properties of the large-pore alumina in component d) are as follows: the specific surface area is 300-380 m 2 / g, the pore volume is 0.8-1.2 mL / g, and the average pore diameter is 8-20 nm.

[0028] According to the present invention, preferably, the composition of the shape-selective cracking catalyst in step (2), based on the mass of the catalyst, includes:

[0029] a) 55%-72% of ZSM-5 molecular sieve;

[0030] b) 5%-15% of molybdenum and / or tungsten, and 2%-5% of cobalt and / or nickel, calculated as oxides;

[0031] c) 1%-13% of binder;

[0032] d) 8%-37% of large-pore alumina.

[0033] According to the present invention, the specific surface area of the shape-selective cracking catalyst in step (2) is 300-500 m 2 / g, and the pore volume is 0.30-0.50 mL / g.

[0034] According to the present invention, the preparation method of the shape-selective cracking catalyst in step (2) can be prepared according to the conventional methods in the art. First, the molecular sieve and the binder are shaped, then dried and calcined, and then the metal components are loaded; the loading of the metal components preferably adopts the impregnation method.

[0035] According to the present invention, preferably, the mass content of C7 + n-alkanes in step (2) is controlled at 1.0%-4.0%.

[0036] According to the present invention, the reaction pressure of the shape-selective cracking reaction in step (2) is 2.0-6.0 MPa, preferably 3.0-5.0 MPa.

[0037] According to the present invention, the reaction conditions of the shape-selective cracking reaction 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-oil volume ratio is 100:1 to 2500:1, preferably 400:1 to 2000:1.

[0038] According to the present invention, the overhead oil from the atmospheric column in step (2) may contain impurities such as sulfur and nitrogen. According to actual needs, a hydrofining catalyst may be provided upstream of the shape-selective cracking catalyst to remove impurities such as sulfur and nitrogen. Among them, the nitrogen content in the reaction stream in contact with the shape-selective cracking catalyst is preferably below 50 mg / kg, more preferably below 20 mg / kg. The hydrofining catalyst described above may use 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, 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%.

[0039] According to the present invention, in the product obtained in step (4), the mass ratio of the C6-C8 monocyclic cyclic hydrocarbons to the total cyclic hydrocarbons in the overhead oil raw material from the atmospheric column is 0.40 to 0.80, preferably 0.50 to 0.60.

[0040] According to the present invention, in step (4), the isomer hydrocarbon conversion catalyst may be one or more catalysts. The isomer hydrocarbon conversion catalyst in step (4) has the function of selectively cracking the side chains of isomer hydrocarbons or cyclic hydrocarbons and retaining the monocyclic cyclic hydrocarbons.

[0041] According to the present invention, preferably, the isomer hydrocarbon conversion catalyst in step (4), based on the mass of the catalyst, includes:

[0042] k) The hydrogenation component content is 5 wt% to 40 wt% based on the oxide, preferably 10 wt% to 20 wt%;

[0043] l) The cracking component content is 20 wt% to 80 wt%, preferably 30 wt% to 70 wt%;

[0044] m) The content of the binder is 5 wt% to 75 wt%, preferably 10 wt% to 50 wt%.

[0045] According to the present invention, preferably, the hydrogenation component in component k) includes at least one of Group VIB and / or Group VIII metals, metal oxides, and metal sulfides. Preferably, the hydrogenation component in component k) includes at least one of metals, metal oxides, and metal sulfides of iron, chromium, molybdenum, tungsten, cobalt, and nickel.

[0046] According to the present invention, preferably, the cracking component in component l) comprises an acidic molecular sieve, preferably at least one of Beta molecular sieve and Y molecular sieve, more preferably Beta molecular sieve.

[0047] According to the present invention, preferably, the binder in component m) is alumina and / or silica.

[0048] According to the present invention, the isomerization hydrocarbon conversion catalyst in step (4) can be prepared by a conventional method in the art. First, the molecular sieve and the binder are formed, then dried and calcined, and then the metal component is loaded; the loading of the metal component preferably uses the impregnation method.

[0049] According to the present invention, in step (4), the reaction pressure of the isomerization hydrocarbon conversion reaction is 1 to 5 MPa, preferably 2 to 4 MPa. Preferably, the reaction pressure of the isomerization hydrocarbon conversion reaction in step (4) is 1.0 MPa to 1.5 MPa lower than the pressure of the shape-selective cracking reaction described in step (2).

[0050] According to the present invention, in step (4), the reaction conditions of the isomerization hydrocarbon conversion 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.

[0051] According to the present invention, preferably, the effluent of the isomerization hydrocarbon conversion reaction in step (4) is subjected to supplementary hydrofining.

[0052] According to the present invention, the separation and fractionation system of the effluent of the isomerization hydrocarbon conversion reaction in step (4) can share a set of systems with the separation and fractionation system of the effluent of the shape-selective cracking reaction in step (2).

[0053] Petroleum hydrocarbon compositions are complex and mainly contain paraffins, naphthenes and aromatics, while high-quality ethylene raw materials are small-molecule normal paraffins, and reforming raw materials are monocyclic naphthenes and aromatics. The inventors have found through research that the overhead oil raw material of the atmospheric column can pass through the shape-selective cracking of straight-chain paraffins 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 paraffins, thereby realizing the efficient enrichment of small-molecule normal paraffins in ethylene raw materials, and at the same time retaining monocyclic cyclic hydrocarbons in reforming raw materials as much as possible to realize the efficient enrichment of high-quality reforming raw materials. In this way, the purpose of greatly improving the yield and quality of chemical raw materials can be achieved, and thus the present invention is completed.

[0054] Compared with the prior art, the present invention has the following beneficial technical effects:

[0055] (1) Reforming belongs to cyclization dehydrogenation reaction, which will not change the carbon number of hydrocarbons with different molecular structures in the feedstock. By controlling the carbon number distribution of hydrocarbons in the feedstock, the C9 + aromatic hydrocarbon yield in the reformed product oil can be reduced, and the generation of low-value-added products can be decreased. In the prior art, when producing catalytic reforming feedstock, in order to reduce the C9 + content of cyclic hydrocarbons, the final boiling point of the heavy naphtha obtained by atmospheric separation is generally not higher than 180 °C. In the method for producing 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, especially the C9 + content of monocyclic cyclic hydrocarbons, is increased, while preventing bicyclic aromatic hydrocarbons with higher hydrogenation difficulty from entering the feedstock. Then, through hydrocracking, the C9 + cyclic hydrocarbons are converted into C6 - C9 cyclic hydrocarbons, the final boiling point of the reforming feedstock is increased, and the distillation range of the reforming feedstock is broadened. As is well known, in crude oil, as the distillation range increases, the content of cyclic hydrocarbons also increases. Increasing the final boiling point of the reforming feedstock can not only increase the source of the reforming feedstock, 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. Specifically, the overhead oil of the atmospheric column obtained by atmospheric distillation of crude oil is contacted and reacted with a shape-selective cracking catalyst containing macroporous alumina, which can effectively remove impurities such as sulfur and nitrogen in the reactants, and at the same time selectively crack the straight-chain paraffins and the long straight chains of isoparaffins and naphthenes in the feedstock to generate small-molecule normal paraffins, and control the mass content of C7 + normal paraffins in the reaction effluent to be 0.1% - 5%; then it is contacted and reacted with an isomer hydrocarbon conversion catalyst to selectively crack the isomer side chains on the isoparaffins and cyclic hydrocarbons, and retain the monocyclic cyclic hydrocarbons. In this way, a large amount of the straight-chain alkanes in the feedstock can be converted into gas and light naphtha components, that is, enriched in the ethylene feedstock, while the monocyclic cyclic hydrocarbons are retained in the heavy naphtha fraction, that is, enriched in the reforming feedstock. Through simple fractionation, the efficient separation of alkanes and cyclic hydrocarbons can be realized, increasing high-quality ethylene cracking raw materials while improving the quality of heavy naphtha as the feed for catalytic reforming.

[0056] (2) The content of monocyclic cyclic hydrocarbons in the heavy naphtha obtained by the method of the present invention is high. As the feed for the catalytic reforming unit, it can eliminate the alkane cyclization and dehydrogenation unit in the catalytic reforming unit, and 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, it can selectively carry out the side-chain breaking reaction on cyclic hydrocarbons with more than C9, so that the C6 - C8 cyclic hydrocarbons in the product have a high enrichment degree, and the BTX yield can be greatly increased after catalytic reforming and aromatics extraction.

[0057] (3) The present invention selectively converts the alkanes in the overhead oil of the atmospheric distillation column into small - molecule alkanes. This process consumes a certain amount of hydrogen. However, as a raw material for the ethylene plant, the light hydrocarbons also have a high hydrogen production rate, and the lower the carbon number, the higher the hydrogen production rate. Therefore, most of the hydrogen consumed in the hydrogenation process can be recovered after passing through the ethylene plant. At the same time, as a raw material for ethylene, the light hydrocarbons can significantly increase the yields of ethylene, propylene, and butadiene, and extend the cleaning cycle of the ethylene plant, significantly improving the economic benefits of the plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 is a process flow schematic diagram of Examples 1 - 4;

[0059] MAIN REFERENCE NUMERAL DESCRIPTION:

[0060] 1 - Crude oil, 2 - Electro - desalting, 3 - Flash distillation column, 4 - Light naphtha, 5 - Bottom oil of flash distillation column, 6 - Atmospheric distillation column, 7 - Overhead oil of atmospheric distillation column, 8 - Diesel oil, 9 - Atmospheric residue, 10 - Hydrogen, 11 - Shape - selective cracking reaction zone, 12 - Effluent from shape - selective cracking reaction, 13 - Separator, 14 - Hydrogen - rich gas in gas - phase stream, 15 - Liquid - phase stream, 16 - Fractionating column, 17 - Gas fraction, 18 - Light naphtha, 19 - Heavy naphtha, 20 - Tail oil, 21 - Isomer hydrocarbon conversion reaction zone, 22 - Effluent from isomer hydrocarbon conversion reaction. DETAILED DESCRIPTION OF THE INVENTION

[0061] The functions and effects of the present invention will be further illustrated by the following examples, but the following examples do not limit the method of the present invention.

[0062] In the present invention, unless otherwise specified, % are all mass fractions.

[0063] In the examples and comparative examples, the overall volume space velocity is the ratio of the fresh feed volume to the total volume of the catalyst.

[0064] In the present invention, the shape - selective cracking catalysts in each example are represented by Cat - A plus a number, such as Cat - A1, Cat - A2. The shape - selective cracking catalysts are prepared by the conventional active metal saturation impregnation method, and the physical and chemical properties of the obtained catalysts are shown in Table 1.

[0065] In the present invention, the isomer hydrocarbon conversion catalysts in each example are represented by Cat - B plus a number, such as Cat - B1, Cat - B2. The physical and chemical properties of the catalysts are shown in Table 2. In each example, the isomer hydrocarbon conversion catalysts are prepared by the conventional active metal saturation impregnation method. Among them, the properties of the Beta zeolite used are as follows: the SiO2 / Al2O3 molar ratio 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 are as follows: the SiO2 / Al2O3 molar ratio is 15, the specific surface area is 400 m 2 / g, the pore volume is 0.30 cm 3 / g, and the physicochemical properties of the obtained catalyst are shown in Table 2.

[0066] In the present invention, the feedstock oil in each example is crude oil, and its main properties are shown in Table 3.

[0067] In the present invention, the process flow diagrams of Examples 1 to 4 are as Figure 1 shown. Figure 1 In it, the crude oil 1 enters the flash tower 3 after being electro - desalted 2 to separate 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 to separate 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 shape - selective cracking reaction zone 11 for shape - selective cracking reaction. The effluent 12 from the shape - selective cracking reaction enters the separator 13. The separated gas - phase stream, the hydrogen - rich gas 14, is recycled. The liquid - phase stream 15 enters the fractionating tower 16 to fractionate gas fractions 17, light naphtha 18, heavy naphtha 19 and tail oil 20. The tail oil 20 enters the isohydrocarbon conversion reaction zone 21, and the effluent 22 from the isohydrocarbon conversion reaction is recycled to the inlet of the separator 13.

[0068] In the present invention, the properties of the macroporous alumina in each example are: the specific surface area is 350 m 2 / g, the pore volume is 1.0 mL / g, and the average pore diameter is 15 nm. The binder in Table 1 is small - pore alumina. The properties of the small - pore alumina are: the specific surface area is 260 m 2 / g, the pore volume is 0.4 mL / g, and the average pore diameter is 4 nm.

[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 less than 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 (the overhead oil of the atmospheric tower). The yield of heavy naphtha refers to the mass ratio of heavy naphtha in the hydrocracking product to the fresh hydrocracking feedstock (the overhead oil of the atmospheric tower).

[0072] Examples 1 to 4

[0073] The method for producing chemical raw materials from the crude oil adopts the Figure 1 process, including:

[0074] (1) After the crude oil is desalted electrically, it enters the flash tower to separate the light naphtha fraction, and then enters the atmospheric tower to separate the overhead oil of the atmospheric tower, diesel oil and atmospheric residue;

[0075] (2) In the presence of hydrogen, the overhead oil of the atmospheric tower contacts with the shape-selective cracking catalyst for shape-selective cracking reaction; and the mass content of C7 + n-alkanes in the effluent of the shape-selective cracking reaction is controlled;

[0076] (3) The effluent of the shape-selective cracking reaction 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 tower to fractionate and obtain a gas fraction, light naphtha, heavy naphtha and tail oil;

[0077] (4) In the presence of hydrogen, the tail oil in step (3) contacts with the isohydrocarbon conversion catalyst for isohydrocarbon conversion reaction; the effluent of the isohydrocarbon conversion reaction is separated, and the effluent of the isohydrocarbon conversion reaction shares a set of separation and fractionation systems with the effluent of the shape-selective cracking reaction in step (2).

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

[0079] Comparative Example 1

[0080] The difference from Example 1 is that: the overhead oil of the atmospheric tower directly enters the isohydrocarbon conversion reaction zone and reacts with the Cat-B1 catalyst.

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

[0082] Comparative Example 2

[0083] The difference from Example 1 is that: in step (2), the content of C7 + n-alkanes in the effluent of the shape-selective cracking reaction is 6%.

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

[0085] Comparative Example 3

[0086] The difference from Example 3 is that: the shape-selective cracking reaction zone is filled with the Cat-B2 catalyst.

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

[0088] Comparative Example 4

[0089] The difference from Example 1 is that: the shape-selective cracking reaction zone is filled with the Cat-B1 catalyst and the isohydrocarbon conversion reaction zone is filled with the Cat-B2 catalyst.

[0090] The process conditions and hydrogenation effects in this example are shown in Table 5.

[0091] Comparative Example 5

[0092] It is different from Example 1 in that the reaction pressure of the shape-selective cracking reaction is the same as the reaction pressure of the isohydrocarbon conversion reaction.

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

[0094] Table 1 Physical and Chemical Properties of Shape-Selective Cracking Catalyst

[0095] Catalyst Cat-A1 Cat-A2 <![CDATA[Pore volume, cm 3 / g]]> 0.40 0.50 <![CDATA[Specific surface area, m 2 / g]]> 400 300 Particle size, μm 0.8 0.6 Catalyst composition ZSM-5, wt% 65 58 Mo, wt% 15 5 Ni, wt% 2 5 Binder, wt% 3 2 Macroporous alumina, wt% 15 30 <![CDATA[SiO2 / Al2O3 molar ratio of ZSM-5]]> 40 60

[0096] Table 2 Physical and Chemical Properties of Isohydrocarbon Conversion Catalyst

[0097] 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 Beta, wt% 50 - Y, wt% - 50 <![CDATA[MoO3, wt%]]> 10 10 NiO, wt% 5 5 Alumina, wt% 35 35

[0098] Table 3 Main Properties of Feedstock

[0099]

[0100]

[0101] Table 4 Atmospheric Distillation Process Conditions and Main Properties of Overhead Oil from 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 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

[0103] Continued Table 4

[0104]

[0105] Table 5 Process Conditions and Hydrogenation Effect of Each Example

[0106]

[0107]

[0108] Continued Table 5

[0109]

[0110]

[0111] 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 chemical raw materials from crude oil, the method comprising: (1) After the crude oil is desalted by electro - desalting, it enters a flash tower to separate out the light naphtha fraction, and then enters an atmospheric tower to separate and obtain the overhead oil of the atmospheric tower; wherein, the mass content of bicyclic aromatic hydrocarbons in the overhead oil of the atmospheric tower is not higher than 1.0%; (2) In the presence of hydrogen, the overhead oil of the atmospheric column in step (1) is contacted with a shape-selective cracking catalyst for shape-selective cracking reaction; wherein the mass content of C7 + normal paraffin in the effluent of the shape-selective cracking reaction is controlled to be 0.1% to 5.0%; (3) The effluent from the shape - selective cracking reaction in step (2) is separated and fractionated to obtain a gas fraction, light naphtha, heavy naphtha, and tail oil; (4) In the presence of hydrogen, the tail oil in step (3) contacts an isohydrocarbon conversion catalyst to carry out an isohydrocarbon conversion reaction, and after separation and fractionation, a gas fraction, light naphtha, and heavy naphtha are obtained; The reaction pressure of the isohydrocarbon conversion reaction is 0.5 MPa - 2.0 MPa lower than the reaction pressure of the shape - selective cracking reaction; The composition of the shape - selective cracking catalyst in step (2), based on the mass of the catalyst, includes: a) 55% - 72% molecular sieve; 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; b) At least one metal selected from Group VIB and Group VIII metals, calculated as oxides, in an amount of 3% - 18%; c) 1% - 13% binder; d) 8% - 37% macroporous alumina; The isohydrocarbon conversion catalyst in step (4), based on the mass of the catalyst, includes: k) The content of the hydrogenation component is 5 wt% - 40 wt%, calculated as oxides; l) The content of the cracking component is 20 wt% - 80 wt%; m) The content of the binder is 5 wt% - 75 wt%; Among them, the cracking component in component l) is selected from at least one of Beta molecular sieve and Y molecular sieve; The chemical raw materials include ethane, propane, butane, light naphtha, and heavy naphtha. Among them, 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 lower - carbon olefins.

2. 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.

3. The method according to claim 1, wherein The properties of the crude oil described in step (1) are as follows: the density is 0.85 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.

4. The method according to claim 1, wherein In step (1), the initial boiling point of the overhead oil of the atmospheric tower is 50 °C - 80 °C; the final boiling point is 190 °C - 260 °C; and / or, the mass content of bicyclic aromatic hydrocarbons in the overhead oil of the atmospheric tower is 0.2% - 0.6%.

5. The method according to claim 1, wherein In step (1), the initial boiling point of the overhead oil of the atmospheric tower is 60 °C - 70 °C; the final boiling point is 200 °C - 220 °C.

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

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

8. The method according to claim 1, wherein The composition of the shape - selective cracking catalyst in step (2), based on the mass of the catalyst, includes: a) 55% - 72% ZSM - 5 molecular sieve; b) 5% - 15% molybdenum and / or tungsten, and 2% - 5% cobalt and / or nickel, calculated as oxides; c) 1% - 13% binder; d) 8% - 37% macroporous alumina.

9. The method according to claim 1 or 8, characterized in that, The properties of the macroporous alumina described in component d) are as follows: the specific surface area is 300 - 380 m 2 / g, the pore volume is 0.8 - 1.2 mL / g, and the average pore diameter is 8 - 20 nm.

10. The method according to claim 1, wherein The specific surface area of the shape-selective cracking catalyst described in step (2) is 300 to 500 m 2 / g, and the pore volume is 0.30 to 0.50 mL / g.

11. The method according to claim 1, wherein C7 in step (2) + The mass content of the n-alkane is controlled at 1.0% to 4.0%.

12. The method according to claim 1, wherein The reaction pressure of the shape-selective cracking reaction described in step (2) is 2.0 to 6.0 MPa; and / or, 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.

13. The method according to claim 1, wherein The reaction pressure of the shape-selective cracking reaction described in step (2) is 3.0 to 5.0 MPa; and / or, 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.

14. The method according to claim 1, wherein The isohydrocarbon conversion catalyst in step (4), based on the mass of the catalyst, includes: k) The content of the hydrogenation component is 10 wt% to 20 wt% based on the oxide; l) The content of the cracking component is 30 wt% to 70 wt%; m) The content of the binder is 10 wt% to 50 wt%.

15. The method according to claim 1, characterized in that For component k), the hydrogenation component includes at least one of metals, metal oxides, and metal sulfides of iron, chromium, molybdenum, tungsten, cobalt, and nickel; And / or, for component l), the cracking component is Beta zeolite.

16. The method according to claim 1, wherein In step (4), the reaction pressure of the isomerization hydrocarbon conversion reaction is 1 to 5 MPa.

17. The method according to claim 1, wherein The reaction pressure of the isomerization hydrocarbon conversion reaction in step (4) is 1.0 MPa to 1.5 MPa lower than the pressure of the shape-selective cracking reaction described in step (2).

18. The method according to claim 1, wherein In step (4), the reaction pressure of the isomerization hydrocarbon conversion reaction is 2 to 4 MPa.

19. The method according to claim 1, wherein The reaction conditions for the isomerized hydrocarbon conversion reaction in step (4) 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-to-oil volume ratio is 100:1 to 2500:

1.

20. The method according to claim 1, wherein The reaction conditions for the isomerized hydrocarbon conversion reaction in step (4) 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-to-oil volume ratio is 400:1 to 2000:1.

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