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 comprises: the crude oil is subjected to electrical desalting and then enters a flash distillation tower to separate a light naphtha fraction, which is then separated into an atmospheric tower to obtain atmospheric tower overhead oil; wherein the mass content of tricyclic aromatic hydrocarbons in the atmospheric tower overhead oil is not higher than 1.0%; the atmospheric tower overhead oil is mixed with hydrogen and passed through a normal hydrocarbon conversion reaction zone to carry out a normal hydrocarbon conversion reaction, and the C7 + The mass content of normal paraffins is 0.1% to 5.0%. In the presence of hydrogen, the effluent from the normal hydrocarbon conversion reaction enters a hydrocracking reaction zone for a hydrocracking reaction. The hydrocracking reaction effluent is then fractionated and separated to produce a gas fraction, light naphtha, heavy naphtha, and tail oil. The reaction pressure in the normal hydrocarbon conversion reaction zone is 4 to 7 MPa; the reaction pressure in the hydrocracking reaction zone is 4 to 7 MPa. This method can significantly improve the quality and yield of chemical raw materials.

Description

Technical Field

[0001] The present invention relates to a crude oil processing method, in particular 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 in fuel economy of internal combustion engines, the growth rate of China's refined oil consumption has continued to slow. However, the demand for bulk petrochemical raw materials (referred to as chemical raw materials) such as low-carbon olefins (ethylene, propylene, and butene) and aromatics (benzene, toluene, and xylene, referred to as BTX) has maintained a high growth rate, becoming the main driving force behind the growth of crude oil demand. In this new situation, the production of chemical raw materials from crude oil has become one of the main means for refining and chemical companies to transform and upgrade, improve quality and increase efficiency. In terms of the yield of crude oil into chemical raw materials, the chemical raw material yield of traditional fuel-based refineries is 8% to 12%, and the chemical raw material yield of conventional integrated refining and chemical plants is 10% to 20%. However, the chemical raw material yield of crude oil-to-chemical raw material plants can reach 40% or even 80%. Therefore, the technology of converting crude oil into chemical raw materials has received great attention.

[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 produce a first hydrocracked product stream; b) separating the first hydrocracked 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 produce a second hydrocracked product stream comprising BTX, wherein the second hydrocracking is more severe than the first hydrocracking, d) wherein, in the presence of a C4 hydrocracking catalyst, at least a portion of the intermediate hydrocarbon stream is subjected to C4 hydrocracking to produce 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 hydrocarbon feedstocks, 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 of 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.

[0005] In summary, petroleum hydrocarbons are complex, primarily comprising paraffins, cycloalkanes, and aromatics. Paraffins, especially small-molecule paraffins, are high-quality ethylene feedstocks, while cycloalkanes and aromatics are high-quality reforming feedstocks. Existing technologies for crude oil conversion are unable to achieve mixed processing of different fractions, nor are they able to selectively and efficiently enrich paraffins (including long side chains on cyclic hydrocarbons) into ethylene feedstocks and cyclic hydrocarbons into reforming feedstocks. Therefore, to address these issues, developing an excellent processing method for producing high-quality chemical feedstocks is of great significance. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a method for producing chemical raw materials from crude oil, which uses the top oil of the atmospheric tower as raw material and can greatly improve the quality and yield of the chemical raw materials.

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

[0008] (1) After electro-desalting, the crude oil enters a flash tower to separate a light naphtha fraction, and then enters an atmospheric tower to separate and obtain atmospheric tower top oil; wherein the mass content of tricyclic aromatic hydrocarbons in the atmospheric tower top oil is not higher than 1.0%;

[0009] (2) The atmospheric tower top oil obtained in step (1) is mixed with hydrogen and passed through the normal hydrocarbon conversion reaction zone to carry out normal hydrocarbon conversion reaction, and the C7 + The mass content of normal alkanes is 0.1% to 5.0%;

[0010] (3) in the presence of hydrogen, the normal hydrocarbon conversion reaction effluent of step (2) enters a hydrocracking reaction zone to undergo a hydrocracking reaction, and then the hydrocracking reaction effluent is fractionated and separated to obtain a gas fraction, light naphtha, heavy naphtha, and tail oil;

[0011] The reaction pressure of the normal hydrocarbon conversion reaction zone in step (2) is 4 to 7 MPa; the reaction pressure of the hydrocracking reaction zone in step (3) is 4 to 7 MPa.

[0012] In the above method, the properties of the crude oil in step (1) are as follows: density of 0.80 g / cm 3 ~1.10g / cm 3 , preferably 0.85g / cm 3 ~1.0g / 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 10mg / kg to 100mg / kg, preferably 20mg / kg to 60mg / kg.

[0013] In the above method, the initial distillation point of the atmospheric tower top oil in step (1) is 50°C to 80°C, preferably 60°C to 70°C; and the final distillation point is 280°C to 340°C, preferably 290°C to 320°C.

[0014] In the above method, the atmospheric distillation conditions described in step (1) are as follows: the top pressure is 0.04MPa~0.12MPa, preferably 0.06MPa~0.10MPa; the atmospheric distillation feed temperature is 330℃~390℃, preferably 350℃~370℃.

[0015] According to the present invention, preferably, the mass content of tricyclic aromatic hydrocarbons in the atmospheric tower top oil in step (1) is 0.2% to 0.6%.

[0016] 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 feedstock to produce BTX, and ethane, propane, butane, and light naphtha are used as feedstocks for producing light olefins, such as steam cracking feedstocks to produce ethylene. Propane and butane can also be directly dehydrogenated to produce propylene and butene. Among them, light olefins refer to olefins with a carbon content of less than 4, especially ethylene, propylene, and butadiene.

[0017] According to the present invention, the catalyst loading in the normal hydrocarbon conversion reaction zone in step (2) is specifically performed by sequentially loading the hydrorefining catalyst and the first hydrocracking catalyst along the material flow direction. The first hydrocracking catalyst can be one or more catalysts. The hydrorefining catalyst can be one or more catalysts. The loading ratio of the hydrorefining catalyst to the first hydrocracking catalyst is 0.5 to 5:1 by volume.

[0018] According to the present invention, the hydrorefining catalyst in step (2) can be a conventional hydrorefining catalyst, which is mainly used for hydrodesulfurization, nitrogen and other impurities. The hydrorefining 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, silicon dioxide or titanium oxide; the hydrogenation active metal includes a VIB and / or VIII group metal component. Further preferably, in the hydrorefining catalyst, the VIB group is preferably selected from tungsten and / or molybdenum, and the content of the oxide in the catalyst is 5wt% to 30wt%, preferably 10wt% to 20wt%, and the VIII group is preferably selected from nickel and / or cobalt, and the content of the oxide in the catalyst is 1wt% to 6wt%, preferably 1.5wt% to 5wt%. The content of the carrier in the catalyst is 64wt% to 94wt%, preferably 75wt% to 88.5wt%.

[0019] According to the present invention, in step (2), the first hydrocracking catalyst comprises an active metal component and a support; the support comprises a molecular sieve having the ability to selectively crack normal alkanes, preferably one or more selected from ZSM-5 molecular sieve, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-35, and ZSM-38 molecular sieves, more preferably ZSM-5 molecular sieve. The SiO2 / Al2O3 molar ratio of the ZSM-5 molecular sieve is 20 to 60. The support may further comprise a binder. Preferably, the binder is alumina. The active metal component comprises at least one of a metal of Group VIB and Group VIII, the metal of Group VIB being preferably molybdenum and / or tungsten, and the metal of Group VIII being preferably cobalt and / or nickel.

[0020] According to the present invention, in step (2), preferably, the first hydrocracking catalyst has, based on the weight of the catalyst, a content of Group VIB metal (calculated as oxide) of 5.0% to 15.0%, a content of Group VIII metal (calculated as oxide) of 2.0% to 5.0%, and a content of the carrier of 80.0% to 93.0%.

[0021] According to the present invention, in step (2), preferably, in the carrier of the first hydrocracking catalyst, the content of the binder is 8% to 60%, and the content of the molecular sieve is 40% to 92%, based on the weight of the carrier.

[0022] 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 0.25~0.45mL / g.

[0023] According to the present invention, the preparation method of the first hydrocracking catalyst in step (2) can be prepared according to conventional methods in the art. The preparation method includes preparing a carrier and loading the active metal component, wherein the carrier preparation process is as follows: mechanically mixing the shape-selective cracking molecular sieve and the binder, forming, and then drying and calcining to form a catalyst carrier. The drying and calcining of the carrier can adopt conventional conditions. The drying conditions are: drying at 100°C to 150°C for 1 to 12 hours. The calcining conditions are: calcining at 450°C to 550°C for 2.5 to 6.0 hours.

[0024] According to the present invention, in step (2), in the preparation method of the first hydrocracking catalyst, the method for loading the active metal component is a conventional method, such as a kneading method, an impregnation method, etc., preferably an impregnation method. The impregnation method can be a saturation impregnation method, an excess impregnation method, or a complex impregnation method, that is, the catalyst support is impregnated with a solution containing the desired active component, and then dried and calcined to obtain the first hydrocracking catalyst. The drying conditions are: drying at 100°C to 150°C for 1 to 12 hours. The calcination conditions are: calcining at 450°C to 550°C for 2.5 to 6.0 hours.

[0025] According to the present invention, the nitrogen content in the effluent of the reaction in step (2) is below 50 mg / kg, more preferably below 20 mg / kg.

[0026] According to the present invention, preferably, C7 + The mass content of normal alkanes is 1.0% to 3.0%.

[0027] According to the present invention, preferably, the reaction conditions of the normal hydrocarbon conversion reaction zone in step (2) are as follows: the reaction pressure is 5 to 6 MPa.

[0028] According to the present invention, the reaction conditions of the normal hydrocarbon conversion reaction zone in step (2) are as follows: the average reaction temperature is 250-450°C, preferably 300-400°C; the liquid hourly volume space velocity is 0.1-15.0h -1 , preferably 1.0~5.0h -1 ; The volume ratio of hydrogen to oil is 100:1 to 2500:1, preferably 400:1 to 2000:1.

[0029] According to the present invention, in step (3), the hydrocracking reaction zone is loaded with a second hydrocracking catalyst, which can be one or more catalysts.

[0030] According to the present invention, the hydrocracking reaction effluent obtained in step (3) is a hydrocracking product containing monocyclic cyclic hydrocarbons. In the hydrocracking reaction effluent of step (3), the ratio of the mass of C6-C8 monocyclic cyclic hydrocarbons to the mass of the total cyclic hydrocarbons in the atmospheric tower overhead feedstock is 0.30-0.50, preferably 0.39-0.45.

[0031] According to the present invention, the tail oil obtained after distillation separation of the hydrocracking reaction effluent obtained in step (3) can be recycled to the hydrocracking reaction zone in step (3).

[0032] According to the present invention, the second hydrocracking catalyst in step (3) has the function of ring-opening cracking of polycyclic cyclic hydrocarbons, selectively cracking the side chains of isomeric hydrocarbons or cyclic hydrocarbons and retaining the function of monocyclic cyclic hydrocarbons. The second hydrocracking catalyst includes a cracking component, a hydrogenation component and a binder. The second hydrocracking catalyst can be commercially available or prepared according to existing technology. The hydrogenation component is at least one of the metal, metal oxide, and metal sulfide of the active metal component; the active metal component includes VIB and / or VIII group metals; 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 molecular sieve and Y molecular sieve.

[0033] According to the present invention, preferably, in step (3), the hydrocracking reaction zone is sequentially loaded with a catalyst with a Y molecular sieve as a cracking component and a catalyst with a Beta molecular sieve as a cracking component along the direction of material flow; preferably, the volume ratio of the catalyst with a Y molecular sieve as a cracking component to the catalyst with a Beta molecular sieve as a cracking component is 1:1 to 1:5, preferably 1:2 to 1:4.

[0034] According to the present invention, the second hydrocracking catalyst in step (3) has a hydrogenation component content of 5 wt% to 40 wt%, preferably 10 wt% to 30 wt%, calculated as oxide, based on the weight of the second hydrocracking catalyst; a cracking component content of 10 wt% to 80 wt%, preferably 20 wt% to 60 wt%; and a binder content of 5 wt% to 85 wt%, preferably 10 wt% to 50 wt%.

[0035] According to the present invention, the preparation method of the second hydrocracking catalyst in step (3) can be prepared according to conventional methods in the art. The preparation method includes preparing a carrier and loading the hydrogenation component, wherein the carrier preparation process is as follows: the cracking component and the binder are mechanically mixed, formed, and then dried and calcined to form a catalyst carrier. The drying and calcination of the carrier can adopt conventional conditions. The drying conditions are: drying at 100°C to 150°C for 1 to 12 hours. The calcination conditions are: calcining at 450°C to 550°C for 2.5 to 6.0 hours.

[0036] 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 a kneading method, an impregnation method, etc., preferably an impregnation method. The impregnation method can be a saturation impregnation method, an excess impregnation method, or a complex impregnation method, that is, the catalyst support is impregnated with a solution containing the desired hydrogenation component, and then dried and calcined to obtain the second hydrocracking catalyst. The drying conditions are: drying at 100°C to 150°C for 1 to 12 hours. The calcination conditions are: calcining at 450°C to 550°C for 2.5 to 6.0 hours.

[0037] According to the present invention, preferably, the reaction conditions of the hydrocracking reaction zone in step (3) are as follows: the reaction pressure is 5 to 6 MPa.

[0038] According to the present invention, the reaction conditions of the hydrocracking reaction zone in step (3) are as follows: the average reaction temperature is 250-450°C, preferably 300-400°C; the liquid hourly volume space velocity is 0.1-15.0h -1 , preferably 1.0~5.0h -1 ; The volume ratio of hydrogen to oil is 100:1 to 2500:1, preferably 400:1 to 2000:1.

[0039] According to the present invention, preferably, the normal hydrocarbon conversion reaction zone and the hydrocracking reaction zone adopt the same pressure.

[0040] According to the present invention, preferably, the hydrocracking reaction effluent in step (3) is subjected to supplementary hydrofining. The supplementary hydrofining can be performed by loading a hydrofining catalyst at the bottom of the hydrocracking reaction zone, or by entering a separate hydrofining reaction zone.

[0041] According to the present invention, preferably, the effluent from the hydrocracking reaction in step (3) may also first enter a fractionation system, and the separated heavy naphtha component may be subjected to supplementary hydrorefining.

[0042] According to the present invention, the tail oil obtained in step (3) is circulated to the hydrocracking reaction zone.

[0043] Petroleum hydrocarbons are complex, primarily comprising paraffins, cycloalkanes, and aromatics. High-quality ethylene feedstocks are small-molecule normal alkanes, while reforming feedstocks are monocyclic cycloalkanes and aromatics. The inventors discovered through research that the technical solution of the present invention can highly selectively generate small-molecule normal alkanes, thereby efficiently enriching them in the ethylene feedstock while simultaneously retaining as many monocyclic cyclic hydrocarbons as possible in heavy naphtha, thereby efficiently enriching high-quality reforming feedstock. This significantly improves the yield and quality of chemical feedstocks (i.e., ethylene feedstock and reforming feedstock), leading to the completion of the present invention.

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

[0045] (1) In the prior art, when diesel is used as a raw material for hydrocracking to produce chemical raw materials, the final distillation point of the diesel fraction obtained by atmospheric distillation is generally 350-380°C, which also makes the content of tricyclic aromatics in the diesel fraction relatively high. A higher reaction pressure is required to achieve hydrocracking of tricyclic aromatics. The higher reaction pressure will also cause some monocyclic aromatics to undergo ring-opening cracking during the hydrocracking process, resulting in loss of aromatics. After the crude oil of the present invention enters the atmospheric tower, the tricyclic aromatics content of the atmospheric tower top oil is controlled to be no more than 1%, and an appropriate reaction pressure is selected to achieve mixed processing of monocyclic aromatics and dicyclic aromatics, thereby reducing the loss of aromatics in the raw material during the hydrogenation process and increasing the aromatic content in the hydrogenated product. The atmospheric tower top oil raw material and hydrogen enter the normal hydrocarbon conversion reaction zone, mainly to selectively crack the normal alkanes and the long straight-chain isoalkanes and cycloalkanes containing long straight chains in the raw material to generate small molecular normal alkanes, so that C7 + The content of normal alkanes is between 0.1% and 5.0%. The effluent from the normal hydrocarbon conversion reaction enters the hydrocracking reaction zone, which mainly performs ring-opening cracking of polycyclic cyclic hydrocarbons while retaining monocyclic cyclic hydrocarbons and further breaks the side chains of each hydrocarbon to generate small molecular hydrocarbons. In this way, a large amount of chain alkanes in the feedstock can be converted into gas and light naphtha components, that is, enriched in the ethylene feedstock, while monocyclic cyclic hydrocarbons are retained in the heavy naphtha fraction, that is, enriched in the reforming feedstock. Through simple fractional distillation, efficient separation of chain alkanes and cyclic hydrocarbons can be achieved, thereby increasing the production of high-quality ethylene cracking feed and improving the quality of heavy naphtha as catalytic reforming feed.

[0046] (2) The heavy naphtha obtained by the method of the present invention has a high content of monocyclic cyclic hydrocarbons. When used as feed for a catalytic reforming unit, the cyclization and dehydrogenation units of the paraffins in the catalytic reforming unit can be eliminated, thereby significantly reducing 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 cyclic hydrocarbons above C9 can be selectively subjected to side chain scission reactions, so that the C6-C8 cyclic hydrocarbons in the product have a high enrichment degree. After catalytic reforming and aromatics extraction, the BTX yield can be significantly increased.

[0047] (3) The present invention selectively converts the chain alkanes in the tower top oil into small molecular alkanes. This process consumes a certain amount of hydrogen, but the hydrogen yield of light hydrocarbons as raw materials for ethylene units is also high. 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, light hydrocarbons as ethylene raw materials can greatly increase the yields of ethylene, propylene and butadiene, and extend the rubber cleaning cycle of the ethylene unit, significantly improving the economic benefits of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 Schematic diagram of the process flow of Examples 1 to 4 of the present invention;

[0049] Description of main reference numerals:

[0050] 1-crude oil, 2-electro-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-normal hydrocarbon conversion reaction zone, 11-normal hydrocarbon conversion reaction effluent, 12-hydrocracking reaction zone, 13-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. DETAILED DESCRIPTION

[0051] The effects and benefits of the present invention are further illustrated below by way of examples, but the following examples do not limit the method of the present invention.

[0052] Unless otherwise specified, % in the present invention refers to mass fraction.

[0053] 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.

[0054] The method of the present invention, such as Figure 1 As shown, the process includes: crude oil 1 enters a flash tower 3 after electro-desalting 2 to be separated into 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 normal hydrocarbon conversion reaction zone 10 for normal hydrocarbon conversion reaction; the normal hydrocarbon conversion reaction effluent 11 enters a hydrocracking reaction zone 12 for hydrocracking reaction; the hydrocracking reaction effluent 13 enters a separator 14; the separated gaseous stream hydrogen-rich gas 15 is recycled; the liquid stream 16 enters a fractionating tower 17 for fractionation to obtain a gas fraction 18, a light naphtha 19, a heavy naphtha 20 and a tail oil 21; the tail oil 21 is circulated to the upstream of the reaction stream of the hydrocracking reaction zone 12.

[0055] 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, and Cat-A4. The first hydrocracking catalyst is prepared by a conventional active metal saturation impregnation method. The physicochemical properties of the obtained catalyst are shown in Table 1.

[0056] In the present invention, the second hydrocracking catalyst in each example is represented by Cat-B plus a number, such as Cat-B1 and Cat-B2. The physicochemical properties of the catalyst are shown in Table 2. The second hydrocracking catalyst in each example was prepared by a conventional active metal saturation impregnation method. The properties of the Beta molecular sieve used in Cat-B1 are as follows: SiO2 / Al2O3 molar ratio of 30, specific surface area of 350m 2 / g, pore volume is 0.32cm 3 / g, the properties of the Y molecular sieve used in Cat-B2 are as follows: SiO2 / Al2O3 molar ratio is 15, specific surface area is 400m 2 / g, pore volume is 0.30cm 3 / g.

[0057] In the present invention, the hydrocracking reaction zones in Examples 1 to 3 are sequentially filled with Cat-B2 and Cat-B1 along the material flow direction.

[0058] In the present invention, the hydrorefining catalyst in each example is represented by Cat-J. The properties of the hydrorefining catalyst are shown in Table 3.

[0059] In the present invention, the feedstock oil in each example is crude oil, and its main properties are shown in Table 4.

[0060] In the present invention, the loading ratio of the hydrorefining catalyst to the first hydrocracking catalyst in each example is 1:2.

[0061] In the present invention, the nitrogen content in the effluent of the reaction in step (2) in each example is less than 20 mg / kg.

[0062] In the present invention, the ethylene raw materials in each example refer to the 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.

[0063] In the present invention, the distillation range of light naphtha is the liquid component less than 60°C, the distillation range of heavy naphtha is 60-175°C, and the distillation range of tail oil is the component greater than 175°C.

[0064] In the present invention, the yield of ethylene feedstock refers to the mass ratio of ethane, propane, butane and light naphtha in the hydrocracking products to the fresh hydrocracking feedstock (atmospheric tower overhead oil), and the yield of heavy naphtha refers to the mass ratio of heavy naphtha in the hydrocracking products to the fresh hydrocracking feedstock (atmospheric tower overhead oil).

[0065] Examples 1 to 4

[0066] The method of producing chemical raw materials from crude oil adopts the following methods: Figure 1 The method specifically includes:

[0067] (1) After electro-desalting, the crude oil enters a flash tower to separate the light naphtha fraction, and then enters an atmospheric tower to separate the atmospheric tower top oil and atmospheric residue;

[0068] (2) The top oil of the atmospheric tower is mixed with hydrogen and passed through the normal hydrocarbon conversion reaction zone to carry out the normal hydrocarbon conversion reaction, and the C7 + The mass content of normal paraffins; the catalyst is loaded in the normal hydrocarbon conversion reaction zone; along the logistics direction, the catalyst is loaded with a hydrorefining catalyst and a first hydrocracking catalyst in sequence;

[0069] (3) In the presence of hydrogen, the effluent from the normal hydrocarbon conversion reaction of step (2) enters a hydrocracking reaction zone for a hydrocracking reaction. The effluent from the 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 a fractionating tower for fractionation to obtain a gas fraction, light naphtha, heavy naphtha and tail oil. The tail oil is circulated to the inlet of the hydrocracking reaction zone.

[0070] The process conditions and hydrogenation effects of each case are shown in Table 6.

[0071] Comparative Example 1

[0072] The difference from Example 1 is that the top oil of the atmospheric tower directly enters the hydrocracking reaction zone after being hydrorefined.

[0073] The process conditions and hydrogenation effects in this example are shown in Table 6.

[0074] Comparative Example 2

[0075] The difference from Example 1 is that in step (1), the C7 + The normal alkane content is 6%.

[0076] The process conditions and hydrogenation effects in this example are shown in Table 6.

[0077] Comparative Example 3

[0078] The difference from Example 1 is that the order of loading the catalysts in the hydrocracking reaction zone is different from that in Example 1. In this example, the order of catalysts Cat-B2 and Cat-B1 is exchanged.

[0079] Specifically, the hydrocracking reaction zone of this example is sequentially loaded with catalyst Cat-B1 and catalyst Cat-B2 along the material flow direction.

[0080] The process conditions and hydrogenation effects in this example are shown in Table 6.

[0081] Comparative Example 4

[0082] The difference from Example 1 is that the mass content of tricyclic aromatic hydrocarbons in the atmospheric tower top oil is 2.3%.

[0083] The process conditions and hydrogenation effects in this example are shown in Table 6.

[0084] Table 1 Physicochemical properties of the first hydrocracking catalyst

[0085] catalyst Cat-A1 Cat-A2 Cat-A3 Cat-A4 <![CDATA[Pore volume, cm 3 / g]]> 0.35 0.45 0.25 0.30 <![CDATA[Specific surface area, m 2 / g]]> 300 200 400 350 Content, wt%, based on the weight of the carrier ZSM-5 58 42 85 75 Alumina 42 58 15 25 Active metal content in catalyst, wt% <![CDATA[MoO3]]> 10.0 15.0 5.0 12.5 NiO 3.5 2.0 5.0 4.0 <![CDATA[SiO2 / Al2O3 molar ratio of ZSM-5]]> 40 60 20 50

[0086] Table 2 Physicochemical properties of the second hydrocracking catalyst

[0087] 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% - 30 <![CDATA[MoO3,wt%]]> 10 20 NiO, wt% 5 5 Alumina, wt% 35 45

[0088] Table 3 Hydrorefining catalyst

[0089] Catalyst properties Cat-J <![CDATA[Pore volume, cm 3 / g]]> 0.35 <![CDATA[Specific surface area, m 2 / g]]> 200 Catalyst composition and content <![CDATA[MoO3,wt%]]> 22 NiO, wt% 4.5 Alumina, wt% 73.5

[0090] Table 4 Main properties of crude oil

[0091] project crude <![CDATA[Density (20 °C) / g·cm -3 > 0.9515 <![CDATA[API, o ]]> 16.8 Carbon residue,% 11.52 Ash content, % 0.067 Sulfur content, % 2.69 Nitrogen content, % 0.42 Gum, % 14.27 Asphaltene, % 6.61 <![CDATA[Metal analysis / μg·g -1 > 60

[0092] Table 5 Atmospheric distillation process conditions and main properties of atmospheric tower top oil

[0093] project Example 1 Example 2 Example 3 Example 4 Tower top pressure / MPa 0.08 0.08 0.08 0.08 Feed temperature / ℃ 350 351 353 355 Distillation range / ℃(ASTM D86) IBP 59 59 59 59 EBP 290 300 310 320 <![CDATA[C7 + Normal alkanes, 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 Amount of tricyclic aromatic hydrocarbons in atmospheric tower top oil, % 0.2 0.3 0.4 0.6

[0094] Table 5

[0095] project Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Tower top pressure / MPa 0.08 0.08 0.08 0.08 Feed temperature / ℃ 350 350 350 360 Distillation range / ℃(ASTM D86) IBP 59 59 59 59 EBP 290 290 290 365 <![CDATA[C7 + Normal alkanes, wt%]]> 18.0 18.0 18.0 16.8 Cyclic hydrocarbons, wt% 48.0 48.0 48.0 51.3 Nitrogen content, mg / kg 46 46 46 88 Amount of tricyclic aromatic hydrocarbons in atmospheric tower top oil, % 0.2 0.2 0.2 2.3

[0096] Table 6 Hydrogenation effect of each case

[0097]

[0098]

[0099] Table 6

[0100]

[0101]

[0102] Note: Catalyst volume ratio*: Comparative Examples 1 and 2 are the volume ratios of Cat-B2 and Cat-B1; Comparative Example 3 is the volume ratio of Cat-B1 and Cat-B2. The loading order of the two catalysts was different for comparison.

[0103] The above describes in detail the specific embodiments of the present invention, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as the contents disclosed by the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for producing chemical raw materials from crude oil, characterized in that: The method comprises: (1) After electro-desalting, the crude oil enters a flash tower to separate a light naphtha fraction, and then enters an atmospheric tower to separate and obtain atmospheric tower top oil; wherein the mass content of tricyclic aromatic hydrocarbons in the atmospheric tower top oil is not higher than 1.0%; (2) The atmospheric tower top oil obtained in step (1) is mixed with hydrogen and passed through the normal hydrocarbon conversion reaction zone to carry out normal hydrocarbon conversion reaction, and the C7 + The mass content of normal alkanes is 0.1%~5.0%; (3) In the presence of hydrogen, the normal hydrocarbon conversion reaction effluent of step (2) enters a hydrocracking reaction zone for a hydrocracking reaction, and then the hydrocracking reaction effluent is fractionated and separated to obtain a gas fraction, light naphtha, heavy naphtha, and tail oil; The reaction pressure of the normal hydrocarbon conversion reaction zone in step (2) is 4-7 MPa; the reaction pressure of the hydrocracking reaction zone in step (3) is 4-7 MPa; The normal hydrocarbon conversion reaction zone in step (2) is loaded with catalyst; the hydrorefining catalyst and the first hydrocracking catalyst are sequentially loaded along the direction of material flow; The first hydrocracking catalyst comprises an active metal component and a support; the support comprises a molecular sieve having the ability to selectively crack normal paraffins, the molecular sieve being 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 comprises at least one of a metal of Group VIB and a metal of Group VIII; The first hydrocracking catalyst comprises, based on the weight of the catalyst, a Group VIB metal content of 5.0% to 15.0% in terms of oxide, a Group VIII metal content of 2.0% to 5.0% in terms of oxide, and a carrier content of 80.0% to 93.0%. The carrier of the first hydrocracking catalyst comprises, based on the weight of the carrier, a binder content of 8% to 60% and a molecular sieve content of 40% to 92%. In step (3), the hydrocracking reaction zone is loaded with a second hydrocracking catalyst; the second hydrocracking catalyst comprises a cracking component, a hydrogenation component and a binder; in step (3), the hydrocracking reaction zone is loaded with a catalyst having a Y molecular sieve as a cracking component and a catalyst having a Beta molecular sieve as a cracking component in sequence along the direction of material flow; The second hydrocracking catalyst has a hydrogenation component content of 5 wt% to 40 wt% in terms of oxides, a cracking component content of 10 wt% to 80 wt% and a binder content of 5 wt% to 85 wt% based on the weight of the second hydrocracking catalyst. The chemical raw materials include ethane, propane, butane, light naphtha and heavy naphtha, wherein heavy naphtha is used as a reforming raw material to produce BTX, and ethane, propane, butane and light naphtha are used as raw materials to produce low-carbon olefins.

2. The method according to claim 1, characterized in that The loading volume ratio of the hydrorefining catalyst to the first hydrocracking catalyst is 0.5 to 5:1; and / or the nitrogen content in the effluent of the reaction in step (2) is below 50 mg / kg.

3. The method according to claim 1, characterized in that The nitrogen content in the effluent from the reaction in step (2) is below 20 mg / kg.

4. The method according to claim 1, characterized in that The hydrorefining catalyst comprises a carrier and a hydrogenation active metal; wherein: The carrier is an inorganic refractory oxide, and the carrier is selected from one or more of alumina, amorphous silica-alumina, silica and titania; and / or the hydrogenation active metal includes a Group VIB and / or Group VIII metal component; In the hydrorefining catalyst, the Group VIB metal is selected from tungsten and / or molybdenum, and the content in the catalyst is 5wt% to 30wt% based on the mass of the oxide; and / or the Group VIII metal is selected from nickel and / or cobalt, and the content in the catalyst is 1wt% to 6wt% based on the mass of the oxide; and / or the content of the carrier in the catalyst is 64wt% to 94wt%.

5. The method according to claim 4, characterized in that: In the hydrorefining catalyst, the content of the Group VIB metal in the catalyst, calculated as the mass of the oxide, is 10 wt% to 20 wt%; and / or the content of the Group VIII metal in the catalyst, calculated as the mass of the oxide, is 1.5 wt% to 5 wt%; and / or the content of the carrier in the catalyst is 75 wt% to 88.5 wt%.

6. The method according to claim 1, characterized in that In the first hydrocracking catalyst, the molecular sieve is ZSM-5 molecular sieve; and / or the Group VIB metal is molybdenum and / or tungsten, and the Group VIII metal is cobalt and / or nickel.

7. The method according to claim 1, characterized in that The properties of the crude oil in step (1) are as follows: density 0.80 g / cm 3 ~1.10g / cm 3 ; Nitrogen mass content is 0.1%~0.6%; sulfur mass content is 1%~6%; metal content is 10mg / kg~100mg / kg.

8. The method according to claim 1, characterized in that: The properties of the crude oil in step (1) are as follows: density 0.85 g / cm 3 ~1.0g / cm 3 ; Nitrogen mass content is 0.2%~0.5%; sulfur mass content is 2%~4%; metal content is 20mg / kg~60mg / kg.

9. The method according to claim 1, characterized in that: In step (1), the initial distillation point of the atmospheric tower top oil is 50°C to 80°C; the final distillation point is 280°C to 340°C; and / or the mass content of tricyclic aromatic hydrocarbons in the atmospheric tower top oil is 0.2% to 0.6%.

10. The method according to claim 1, characterized in that: In step (1), the initial distillation point of the atmospheric tower top oil is 60°C to 70°C; and the final distillation point is 290°C to 320°C.

11. The method according to claim 1, characterized in that: The atmospheric distillation conditions described in step (1) are as follows: the tower top pressure is 0.04MPa~0.12MPa; the atmospheric distillation feed temperature is 330℃~390℃.

12. The method according to claim 1, characterized in that: The atmospheric distillation conditions described in step (1) are as follows: the tower top pressure is 0.06MPa~0.10MPa; the atmospheric distillation feed temperature is 350℃~370℃.

13. The method according to claim 1, characterized in that: The reaction conditions of the normal hydrocarbon conversion reaction zone in step (2) are as follows: average reaction temperature of 250-450°C; liquid hourly volume space velocity of 0.1-15.0h -1 ; The volume ratio of hydrogen to oil is 100:1~2500:1; And / or, the reaction conditions of the hydrocracking reaction zone in step (3) are as follows: average reaction temperature is 250-450°C; liquid hourly volume space velocity is 0.1-15.0h -1 ;The volume ratio of hydrogen to oil is 100:1~2500:

1.

14. The method according to claim 1, characterized in that: The reaction conditions of the normal hydrocarbon conversion reaction zone in step (2) are as follows: average reaction temperature of 300-400°C; liquid hourly volume space velocity of 1.0-5.0h -1 ; The volume ratio of hydrogen to oil is 400:1~2000:1; And / or, the reaction conditions of the hydrocracking reaction zone in step (3) are as follows: average reaction temperature of 300-400°C; liquid hourly volume space velocity of 1.0-5.0h -1 ;The volume ratio of hydrogen to oil is 400:1~2000:

1.

15. The method according to claim 1, wherein: 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 20 wt% to 60 wt%; and the content of the binder is 10 wt% to 50 wt%; and / or, in the second hydrocracking catalyst, 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 comprises a VIB and / or VIII Group metal; the active metal component is at least one of iron, chromium, molybdenum, tungsten, cobalt, and nickel; and / or, in the second hydrocracking catalyst, the binder is alumina and / or silica; And / or, the volume ratio of the catalyst with Y molecular sieve as the cracking component to the catalyst with Beta molecular sieve as the cracking component is 1:1 to 1:

5.

16. The method according to claim 15, characterized in that The volume ratio of the catalyst using Y molecular sieve as the cracking component to the catalyst using Beta molecular sieve as the cracking component is 1:2~1:

4.

17. The method according to claim 1, characterized in that: The reaction pressure of the normal hydrocarbon conversion reaction zone in step (2) is 5-6 MPa; and / or the reaction pressure of the hydrocracking reaction zone in step (3) is 5-6 MPa.

18. The method according to claim 1, wherein: The hydrocracking reaction effluent obtained in step (3) is a hydrocracking product containing monocyclic cyclic hydrocarbons.

19. The method according to claim 1, wherein: In the hydrocracking reaction effluent of step (3), the ratio of the mass of C6-C8 monocyclic cyclic hydrocarbons to the mass of the total cyclic hydrocarbons in the atmospheric tower overhead oil feedstock is 0.30-0.

50.

20. The method according to claim 1, wherein: In the hydrocracking reaction effluent of step (3), the ratio of the mass of C6-C8 monocyclic cyclic hydrocarbons to the mass of the total cyclic hydrocarbons in the atmospheric tower overhead oil feedstock is 0.39-0.

45.

21. The method according to claim 1, wherein: The normal hydrocarbon conversion reaction zone in step (2) and the hydrocracking reaction zone in step (3) adopt the same pressure.

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