A process and system for the conversion of a sulfur-containing feedstock hydrocarbon

Abstract

The present application relates to a kind of conversion method and system of sulfur-containing raw hydrocarbon.The conversion method of sulfur-containing raw hydrocarbon according to the present application, including the following steps:1) providing sulfur-containing raw hydrocarbon, wherein the sulfur content of the raw hydrocarbon is 50-5000mg / kg, relative to the total weight of the raw hydrocarbon,2) chemical conversion the sulfur-containing raw hydrocarbon, obtain sulfur-containing conversion product, and 3) steam cracking the sulfur-containing conversion product and obtain the cracking product containing ethylene.According to the present application, the sulfur content in the raw material can be effectively converted into hydrogen sulfide, and selectively retained in the conversion product, which can reduce the amount of sulfur injection or even eliminate the sulfur injection when used as ethylene raw material, achieving high-value utilization of non-value components.

Description

Technical Field

[0001] This invention relates to the field of petrochemical technology, and more specifically, to a method and system for converting sulfur-containing hydrocarbon feedstocks. Background Technology

[0002] During the ethylene production process, the feedstock undergoes a series of complex chemical reactions after high-temperature pyrolysis, leading to varying degrees of coking on the inner walls of the radiant furnace tubes and the quench boiler jacket. As the coke layer thickens, the heat transfer resistance of the furnace tubes increases, preventing timely heat transfer from the outside to the feedstock inside, severely impacting the pyrolysis depth. Furthermore, the continuously rising temperature of the furnace tube surface can cause localized overheating, shortening the tube's lifespan. When the temperature exceeds the maximum design temperature of the furnace tube material, the furnace must be shut down for cleaning. Therefore, if the ethylene feedstock contains little or no sulfides, sulfur needs to be injected during the reaction to prevent coking in the furnace tubes; if the ethylene feedstock contains a certain amount of sulfides, sulfur injection is also necessary to reduce the unit's operating costs.

[0003] With the rapid development of my country's chemical industry, ethylene production capacity has increased year by year. As a result, the demand for ethylene feedstock has also been increasing. How to broaden the selection range of ethylene feedstock and how to obtain high-quality ethylene feedstock have become urgent problems to be solved in the development of the ethylene industry. Summary of the Invention

[0004] The inventors of this invention discovered that ethylene feedstock obtained through hydrogenation processes undergoes a process where organic sulfur is removed and converted into hydrogen sulfide during the hydrogenation reaction. This hydrogen sulfide is then removed during product separation. Therefore, the sulfur content in ethylene feedstock is typically low, requiring sulfur injection before entering the ethylene cracking furnace to prevent coking of the furnace tubes. If a portion of hydrogen sulfide is retained in the hydrogenation products during separation, the sulfur injection before entering the ethylene cracking furnace can be reduced or eliminated when the hydrogenated products are used as ethylene feedstock, enabling high-value utilization of the waste gas.

[0005] Specifically, the present invention relates to the following aspects.

[0006] 1. A method for converting sulfur-containing hydrocarbon feedstock, comprising the following steps:

[0007] 1) Provide sulfur-containing feedstock hydrocarbons, wherein the sulfur content of the feedstock hydrocarbons is 50-5000 mg / kg (preferably 200-1000 mg / kg), relative to the total weight of the feedstock hydrocarbons.

[0008] 2) Chemically convert the sulfur-containing raw material hydrocarbon to obtain sulfur-containing conversion products, and

[0009] 3) Steam cracking of the sulfur-containing conversion products yields cracking products containing ethylene.

[0010] 2. The conversion method of claim 1, wherein the sulfur-containing feedstock hydrocarbon contains C5-C6 isoalkanes, the chemical conversion is to cause at least a portion (e.g., more than 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%, or 90 wt%) of the C5-C6 isoalkanes to undergo a conversion reaction in the presence of hydrogen, and the conversion product contains C2-C6 n-alkanes.

[0011] 3. The conversion method according to any of the foregoing or the following, wherein the initial boiling point of the sulfur-containing feedstock hydrocarbon is 10-30°C (preferably 15-25°C) and the final boiling point is 50-100°C (preferably 55-70°C).

[0012] 4. The conversion method according to any of the foregoing or hereinafter described, wherein the sulfur-containing feedstock hydrocarbon contains C 7+ The hydrocarbon content is 0-10 wt% (preferably 0.5-5 wt%), the C5-C6 isoalkanes content is 50 wt% or more (preferably 60-90 wt%, more preferably 70-80 wt%), the C5-C6 n-alkanes content is 10-30 wt% (preferably 15-25 wt%), the C4-hydrogen content is 0-10 wt% (preferably 2-5 wt%), the cyclic hydrocarbon content is 1-10 wt% (preferably 2-5 wt%), and the sulfur content is 50-5000 mg / kg (preferably 200-1000 mg / kg). Based on a total weight of 100 wt%, and / or, the conversion product contains no more than 5 wt% (preferably no more than 1 wt%) of C7+ hydrocarbons, 0-50 wt% (preferably 10-40 wt%) of C5-C6 isoalkanes, 40-90 wt% (preferably 50-80 wt%) of C2-C6 n-alkanes, no more than 3 wt% (preferably no more than 1 wt%) of cyclic hydrocarbons, and has a sulfur content of 50-1000 mg / kg (preferably 100-200 mg / kg), based on a total weight of 100 wt% of the conversion product.

[0013] 5. The conversion method according to any of the foregoing or the following, wherein the sulfur-containing feedstock hydrocarbon is a light naphtha component obtained by cracking (e.g., hydrocracking or catalytic cracking) a hydrocarbon feedstock.

[0014] 6. The conversion method according to any of the foregoing or hereinafter described, wherein the conversion process needs to be carried out in the presence of a catalyst, and the catalyst comprises an acidic component and a hydrogenation component.

[0015] 7. The conversion method according to any of the foregoing or hereinafter described, wherein the acidic component is a molecular sieve with shape-selective catalytic properties, preferably selected from one or more of mordenite, ZSM molecular sieve, SAPO molecular sieve and EU-1 molecular sieve, more preferably selected from one or more of mordenite and ZSM molecular sieve, particularly preferably selected from one or more of mordenite, ZSM-5 molecular sieve, ZSM-11 molecular sieve, ZSM-12 molecular sieve, ZSM-22 molecular sieve, ZSM-23 molecular sieve, ZSM-35 molecular sieve, Beta molecular sieve and ZSM-38 molecular sieve, especially selected from one or more of mordenite and ZSM-5 molecular sieve.

[0016] 8. The conversion method according to any of the foregoing or hereinafter, wherein the catalyst further comprises a binder (preferably alumina), and the content of the binder is 5-65 wt% (preferably 10-35 wt%) based on the weight of the catalyst.

[0017] 9. The conversion method according to any of the foregoing or hereinafter, wherein the hydrogenation component is selected from at least one metal including Group VIB and Group VIII, wherein the Group VIB metal is preferably molybdenum and / or tungsten, and the Group VIII metal is preferably cobalt and / or nickel.

[0018] 10. The conversion method according to any of the foregoing or the following, wherein, based on the weight of the catalyst, the content of the Group VIB metal (as oxide) is 5.0-30.0 wt% (preferably 10-20 wt%), and the content of the Group VIII non-precious metal (as oxide) is 0.5-15.0 wt% (preferably 3-10 wt%).

[0019] 11. The conversion method according to any of the foregoing or hereinafter, wherein the content of the acidic component is 30-80 wt% (preferably 40-70 wt%) based on the weight of the catalyst.

[0020] 12. The conversion method according to any of the foregoing or hereinafter described, wherein the catalyst has a specific surface area of ​​200-400 m². 2 / g, with a pore volume of 0.25-0.45mL / g.

[0021] 13. The conversion method according to any of the foregoing or hereinafter described aspects, wherein the reaction conditions of the conversion reaction include: a reaction pressure of 0.5-10.0 MPaG (preferably 2.0-8.0 MPaG or 2.0-5.0 MPaG), a reaction temperature of 250-500°C (preferably 350-450°C), and a liquid hourly space velocity of 0.1-15.0 h⁻¹. -1 (Preferred 0.5-5.0h) -1The hydrogen-to-oil volume ratio is 10:1-2500:1 (preferably 100:1-2000:1 or 100:1-1000:1).

[0022] 14. The conversion method according to any of the foregoing or hereinafter, wherein the steam cracking operating conditions include: a reaction temperature of 750-900℃, a reaction pressure of 0.1-0.5MPaG, a water-to-oil mass ratio of 0.2-0.6, and a sulfur content of 100-200mg / kg.

[0023] 15. The method according to any of the foregoing or hereinafter described further comprises the following step:

[0024] The conversion products are separated to obtain a separate stream mainly composed of C2-C6 n-alkanes (e.g., accounting for more than 80 wt%, 90 wt%, or 95 wt% of the total).

[0025] Steam cracking of the separated feed stream yields cracking products containing ethylene.

[0026] 16. The conversion method according to any of the foregoing or hereinafter, wherein the weight ratio of the separated feed stream to the feed hydrocarbon is 0.4-0.9:1 (preferably 0.5-0.8:1).

[0027] 17. The method according to any of the foregoing or the following aspects further comprises the step of:

[0028] The conversion products are separated to obtain a n-alkanes stream dominated by C4-C6 (e.g., accounting for more than 80 wt%, 90 wt%, or 95 wt% of the total) and / or a low-carbon stream dominated by C2-C3 hydrocarbons (e.g., accounting for more than 90 wt% or 95 wt% of the total).

[0029] Steam cracking of the orthocarbon feed stream and / or the low-carbon feed stream yields cracking products containing ethylene.

[0030] 18. A conversion system for sulfur-containing hydrocarbon feedstocks, comprising the following units:

[0031] 1) A feedstock hydrocarbon supply unit configured to provide sulfur-containing feedstock hydrocarbons, wherein the sulfur content of the feedstock hydrocarbons is 50-5000 mg / kg (preferably 200-1000 mg / kg), relative to the total weight of the feedstock hydrocarbons.

[0032] 2) A feedstock hydrocarbon conversion unit, configured to chemically convert the sulfur-containing feedstock hydrocarbons to obtain sulfur-containing conversion products, and

[0033] 3) A steam cracking unit configured to steam crack the sulfur-containing conversion products to obtain cracking products containing ethylene.

[0034] Compared with the prior art, the method and system provided by the present invention can achieve one or more or a combination of the following technical effects:

[0035] 1. In the process of producing ethylene through steam cracking, the sulfur content of the feedstock needs to be controlled to a certain level. If the sulfur content is too low, sulfur needs to be injected before the cracking furnace; otherwise, it will accelerate coking in the ethylene cracking furnace, affecting the operating cycle and cracking effect. Conversely, if the sulfur content in the feedstock is too high, it will increase the operating cost of subsequent desulfurization. When producing ethylene feedstock through hydrogenation, by processing the feedstock and controlling the appropriate sulfur content in the hydrogenation products, the sulfur content in the feedstock of the ethylene plant can be effectively controlled, reducing or even eliminating the need for sulfur injection into the ethylene cracking furnace.

[0036] 2. During the hydrogenation reaction of raw hydrocarbon feedstocks, organic sulfides are converted into hydrogen sulfide. This hydrogen sulfide is a worthless product for the hydrogenation unit and may even require removal through separation methods such as stripping. The removed hydrogen sulfide then requires further harmless treatment. However, when hydrogenation products containing a certain amount of hydrogen sulfide are used as ethylene feedstock, they can solve the problem of sulfur injection into ethylene production, achieving high-value utilization of this useless component. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of a process flow of the present invention.

[0038] exist Figure 1 In the middle, 1-sulfur-containing hydrocarbon stream, 2-hydrogen gas, 3-hydrogenation conversion reaction zone, 4-hydrogenation conversion reaction zone effluent, 5-high pressure separator, 6-hydrogen-rich gas stream, 7-liquid stream.

[0039] Figure 2 This is a schematic diagram of a process flow of the present invention.

[0040] exist Figure 2 In the diagram, 1-sulfur-containing hydrocarbon stream, 2-hydrogen, 3-hydrogenation conversion reaction zone, 4-hydrogenation conversion reaction zone effluent, 5-high-pressure separator, 6-hydrogen-rich gas stream, 7-liquid stream, 8-distillation tower, 9-gas phase product, 10-liquid phase product. Detailed Implementation

[0041] The specific embodiments of the present invention will be described in detail below. However, it should be noted that the scope of protection of the present invention is not limited to these specific embodiments, but is determined by the claims in the appendix.

[0042] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0043] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0044] In the context of this invention, all numerical values ​​of parameters (e.g., quantity or condition) should be understood to be modified by the term “about” in all cases, regardless of whether “about” actually appears before the numerical value.

[0045] In the context of this invention, unless otherwise specified, the various devices used in this invention may use structures conventionally chosen in the art, and there are no particular limitations.

[0046] In the context of this invention, the initial boiling point and final boiling point are measured in accordance with ASTM D86 measurement method.

[0047] In the context of this invention, the method for measuring sulfur content is in accordance with GB / T380.

[0048] In the context of this invention, the term "C2-C6 n-alkanes" refers to n-alkanes with 2 to 6 carbon atoms. It should be particularly clarified that although there is no distinction between n-alkanes and isoalkanes among alkanes with 2 to 3 carbon atoms, for ease of description, this invention also considers alkanes with 2 to 3 carbon atoms as n-alkanes. Furthermore, unless otherwise specified, this invention may use the term to refer to any one or more of n-alkanes with 2 to 6 carbon atoms, or it may refer to all n-alkanes with 2 to 6 carbon atoms.

[0049] In the context of this invention, cyclic hydrocarbons refer to hydrocarbons such as cycloalkanes and aromatics that have a cyclic structure in their molecular structure.

[0050] Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this instruction manual are based on weight, and the pressure is gauge pressure.

[0051] In the context of this invention, any two or more technical solutions or aspects of this invention can be arbitrarily combined, and the resulting technical solutions are part of the original disclosure of this specification and also fall within the protection scope of this invention.

[0052] According to the technical solution of this application, a method for converting sulfur-containing hydrocarbon feedstock is provided. According to this invention, during the hydrogenation reaction, a portion of the hydrogen sulfide generated is retained in the hydrogenation product during separation. Thus, when the hydrogenation product is used as an ethylene feedstock, sulfur injection before entering the ethylene cracking furnace can be reduced or even eliminated, enabling high-value utilization of waste gas.

[0053] According to the technical solution of this application, the method includes the step of providing a sulfur-containing feedstock hydrocarbon. According to the present invention, the sulfur-containing feedstock hydrocarbon can be manufactured by any method known in the art, as long as it meets the requirements of the present invention for sulfur-containing feedstock hydrocarbon. Examples of methods for manufacturing the sulfur-containing feedstock hydrocarbon include hydrocracking, catalytic cracking, or atmospheric and vacuum distillation. Preferably, the initial boiling point of the sulfur-containing feedstock hydrocarbon is 10-30°C (preferably 15-25°C), and the final boiling point is 50-100°C (preferably 55-70°C). More preferably, the sulfur-containing feedstock hydrocarbon is a light naphtha component obtained by hydrocracking a hydrocarbon oil feedstock.

[0054] According to the present invention, the sulfur content of the feedstock hydrocarbon is 50-5000 mg / kg (preferably 200-1000 mg / kg) relative to the total weight of the feedstock hydrocarbon. The inventors of the present invention have discovered that excessively low sulfur content in the feedstock can easily cause continuous sulfur loss from the hydrogenation catalyst during the reaction process, leading to changes in the valence state of the hydrogenated components and consequently catalyst deactivation. Simultaneously, excessively low sulfur content prevents the transfer of sulfur from the feedstock to the hydrogenation products, failing to address the sulfur injection problem in ethylene plants. Excessively high sulfur content in the feedstock increases the difficulty of sulfur removal during the hydrogenation reaction, especially for low-pressure reaction processes, where the difficulty of hydrodesulfurization increases significantly. Furthermore, when excessive sulfides remain in the hydrogenation products and enter the ethylene plant, it also increases the sulfur content of the ethylene products, further complicating subsequent removal.

[0055] According to the technical solution of this application, in order to improve the technical effect of the present invention, it is preferable that the sulfur-containing feedstock hydrocarbon contains C5-C6 isoalkanes. More preferably, the content of C5-C6 isoalkanes in the feedstock hydrocarbon is generally 50 wt% or more (preferably 60-90 wt%, more preferably 70-80 wt%), based on a total weight of 100 wt% of the feedstock hydrocarbon. According to the present invention, the isoalkane content in the feedstock hydrocarbon must be within a certain range. When feedstocks with lower isoalkane content are used directly as ethylene feedstocks, a higher ethylene product yield can still be obtained. Although the proportion of n-alkanes can be increased after conversion, the increase is limited. Feedstocks with higher isoalkane content are more difficult to obtain, and cannot be obtained directly through conventional distillation; they require high-energy-consuming operating units.

[0056] According to the technical solution of this invention, the C in the raw material hydrocarbon is...7+ There is no particular limitation on the hydrocarbon content, but in order to make the technical effect of the present invention more superior, the C content of the raw material hydrocarbon is limited. 7+ The hydrocarbon content is generally 0-10 wt% (preferably 0.5-5 wt%), based on a total weight of 100 wt% of the raw material hydrocarbons. The inventors of this invention have discovered that the C content in the raw material hydrocarbons... 7+ Excessive hydrocarbon content results in the inclusion of complex macromolecular components in the raw materials. These macromolecular components are difficult to enter the molecular sieve channels with shape-selective conversion function, and are difficult to be converted into the main target product of this invention, n-alkanes, through the conversion process, which is detrimental to this invention.

[0057] According to the technical solution of this application, there is no particular limitation on the content of C5-C6 n-alkanes in the raw material hydrocarbons. However, in order to improve the technical effect of this invention, the content of C5-C6 n-alkanes in the raw material hydrocarbons is generally 10-30 wt% (preferably 15-25 wt%), based on a total weight of 100 wt% of the raw material hydrocarbons. The inventors of this invention have discovered that the conversion of isoalkanes to n-alkanes in the raw material hydrocarbons is affected by the chemical reaction equilibrium. If the content of n-alkanes is too high, the chemical reaction equilibrium will proceed in the reverse direction, causing n-alkanes to be converted into isoalkanes, affecting the conversion effect of isoalkanes, which is detrimental to this invention.

[0058] According to the technical solution of this application, there is no particular limitation on the content of C4-hydrogen in the feedstock hydrocarbons. However, in order to improve the technical effect of this invention, the content of C4-hydrogen in the feedstock hydrocarbons is generally 0-10 wt% (preferably 2-5 wt%), based on a total weight of 100 wt% of the feedstock hydrocarbons. The inventors of this invention have found that when C4-hydrogen and C5-C6 hydrocarbons are mixed as feedstocks in a hydroconversion process, the feedstocks need to be pressurized before entering the feed pump to keep the C4-hydrogens in a liquid state, which increases the operational difficulty. Furthermore, the inventors of this invention have found that as the number of carbon atoms in the hydrocarbon molecule decreases, the difficulty of the conversion reaction gradually increases. Under reaction conditions suitable for C5-C6 isoalkanes, the conversion of C4 hydrocarbons is more difficult (e.g., the conversion rate is generally less than 20%). Therefore, an excessively high content of C4 hydrocarbons will significantly inhibit the conversion activity of the feedstock hydrocarbons in this invention, which is detrimental to this invention.

[0059] According to the technical solution of this application, there is no particular limitation on the content of cyclic hydrocarbons in the raw material hydrocarbons. However, in order to improve the technical effect of this invention, the content of cyclic hydrocarbons in the raw material hydrocarbons is generally 1-10 wt% (preferably 2-5 wt%), based on a total weight of 100 wt% of the raw material hydrocarbons. The inventors of this invention have discovered that, due to the influence of reaction conditions and the molecular sieve pore structure, cycloalkanes with complex branched structures and aromatic hydrocarbons with arbitrary structures are difficult to convert during the conversion process of this invention. These cyclic hydrocarbons, after passing through the reaction system, do not change their molecular structure and directly enter the ethylene unit as conversion products, affecting the yield of ethylene and trienes in the ethylene unit, which is detrimental to this invention.

[0060] According to the technical solution of this application, the method includes the step of chemically converting the sulfur-containing raw material hydrocarbon to obtain a sulfur-containing conversion product. Preferably, the chemical conversion involves causing at least a portion of the C5-C6 isoalkanes to undergo a conversion reaction in the presence of hydrogen. Here, "at least a portion" means, for example, 30 wt% or more, 40 wt% or more, 50 wt% or more, 60 wt% or more, 70 wt% or more, 80 wt% or more, or 90 wt% or more of the total amount. According to the present invention, the conversion rate of the C5-C6 isoalkanes is not particularly limited. Therefore, the conversion rate of the C5-C6 isoalkanes can be achieved in a single conversion reaction (single-pass conversion rate), or it can be achieved after multiple recycling processes (e.g., after separating unreacted C5-C6 isoalkanes from the conversion product before carrying out the conversion reaction).

[0061] According to the technical solution of this application, the conversion reaction can be a hydronormative reaction to obtain a conversion product with C4-C6 n-alkanes as the main product, or a hydrocracking reaction to obtain a conversion product with C2-C3 hydrocarbons as the main product. The inventors of this invention have discovered that C5 and C6 isoalkanes mainly undergo two reaction pathways in the conversion process of this invention: one is the direct conversion of isoalkanes to n-alkanes with the same number of carbon atoms, i.e., the nmative reaction; the other is the direct cracking of isoalkanes to lower-carbon alkanes, i.e., the cracking reaction. Both reaction pathways require a catalyst with shape-selective catalysis function to occur, and the acidity of the molecular sieve also affects the reaction process. Molecular sieves with a high content of strong acid centers tend to undergo cracking reactions, while molecular sieves with a high content of moderately strong acid centers tend to undergo nmative reactions. The normalization reaction is affected by the content of isoalkanes in the feedstock. The higher the content of isoalkanes in the feedstock, the more the normalization reaction tends to proceed in the forward direction. However, as the content of n-alkanes generated by conversion increases, the normalization reaction will be inhibited. At this point, we need to increase the cracking reaction to further improve the yield of n-alkanes in the conversion products.

[0062] According to the technical solution of this application, the reaction conditions for the conversion reaction include: a reaction pressure of 0.5-10.0 MPaG (preferably 2.0-8.0 MPaG or 2.0-5.0 MPaG), a reaction temperature of 250-500℃ (preferably 350-450℃), and a liquid hourly space velocity of 0.1-15.0 h⁻¹. -1 (Preferred 0.5-5.0h) -1 The hydrogen-to-oil volume ratio is 10:1-2500:1 (preferably 100:1-2000:1 or 100:1-1000:1). The inventors of this invention have discovered that, compared to prior art feedstock hydrocarbon conversion reactions (such as C4 feedstock hydrocarbon conversion reactions), the reaction conditions of the conversion reaction of this invention are milder, especially the reaction temperature is lower, typically 10-50°C lower. The inventors of this invention have also discovered that, at this lower reaction temperature, C5-C6 isoalkanes still exhibit high conversion rates; for example, C5-C6 isoalkanes can exhibit single-pass conversion rates of 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%, or 90 wt% or higher under the reaction conditions of this invention. In comparison, C4 hydrocarbons are more difficult to convert due to their molecular structure. The conversion process first requires a dehydrogenation reaction, which is far more difficult than that of C5-C6 isoalkanes. This necessitates more stringent reaction conditions for the conversion of C4 hydrocarbons (e.g., reaction temperatures 20-30°C higher). Furthermore, for C… 7+ The conversion of components is affected by reaction conditions and the pore structure of the molecular sieve. Complexly branched cycloalkanes and aromatics with arbitrary structures are difficult to convert in the process of this invention. These cyclic hydrocarbons, after passing through the reaction system, do not undergo molecular structural changes and directly enter the ethylene unit as conversion products, affecting the yield of ethylene and trienes in the ethylene unit.

[0063] According to the technical solution of this application, the conversion reaction is carried out in the presence of a catalyst, and the catalyst comprises a molecular sieve and an active metal component.

[0064] According to the technical solution of this application, the molecular sieve is a molecular sieve with shape-selective catalytic properties, preferably selected from one or more of mordenite, ZSM molecular sieve, SAPO molecular sieve, and EU-1 molecular sieve, more preferably selected from one or more of mordenite and ZSM molecular sieve, particularly preferably selected from one or more of mordenite, ZSM-5 molecular sieve, ZSM-11 molecular sieve, ZSM-12 molecular sieve, ZSM-22 molecular sieve, ZSM-23 molecular sieve, ZSM-35 molecular sieve, Beta molecular sieve, and ZSM-38 molecular sieve, especially selected from one or more of mordenite and ZSM-5 molecular sieve. Here, based on the weight of the catalyst, the content of the molecular sieve is 30-80 wt% (preferably 40-70 wt%). The inventors of this invention have discovered that the acid strength of the molecular sieve directly affects the reaction characteristics of isoalkanes. Molecular sieves with more strong acid centers are more prone to cracking reactions, such as ZSM-5 molecular sieve; while those with more moderately strong acid centers are more prone to normalization reactions, such as mordenite. Therefore, according to the present invention, different reaction pathways can be achieved by selecting the acid strength of the molecular sieve.

[0065] According to the technical solution of this application, the hydrogenation component is selected from at least one metal including Group VIB and Group VIII. The Group VIB metal is preferably molybdenum and / or tungsten, and the Group VIII metal is preferably cobalt and / or nickel. Here, based on the weight of the catalyst, the content of the Group VIB metal (calculated as oxide) is 5.0-30.0 wt% (10.0-20.0 wt%), and the content of the Group VIII non-precious metal (calculated as oxide) is 0.5-15.0 wt% (preferably 3.0-10.0 wt%).

[0066] According to the technical solution of this application, the catalyst further includes a binder. The type of binder can be conventionally chosen in the art, including but not limited to alumina and silicon dioxide, with alumina being preferred. Here, based on the weight of the catalyst, the content of the binder is 5-65 wt% (preferably 10-35 wt%).

[0067] According to the technical solution of this invention, the catalyst has a specific surface area of ​​200-400 m². 2 / g, with a pore volume of 0.25-0.45mL / g.

[0068] According to the technical solution of this application, the catalyst can be prepared using conventional methods in the art. The preparation method includes the preparation of a support and the loading of an active metal component. The support preparation process is as follows: the molecular sieve and the binder are mechanically mixed, shaped, dried, and calcined to form the catalyst support. The drying and calcination of the support can be performed under conventional conditions. The drying conditions are: drying at 100℃-150℃ for 1-12 hours. The calcination conditions are: calcination at 450℃-550℃ for 2.5-6.0 hours.

[0069] According to the technical solution of this application, the method for preparing the catalyst, in which the active metal component is loaded, is a conventional method, such as kneading or impregnation, with impregnation being preferred. The impregnation method can be saturated impregnation, excess impregnation, or complex impregnation, that is, impregnating the catalyst support with a solution containing the desired active metal component, followed by drying and calcination to obtain the first catalyst. The drying conditions are: drying at 100℃-150℃ for 1-12 hours. The calcination conditions are: calcination at 450℃-550℃ for 2.5-6.0 hours.

[0070] According to the present invention, the conversion product comprises C2-C6 n-alkanes and contains sulfur. Preferably, the sulfur contained in the sulfur-containing feedstock hydrocarbons is substantially entirely retained in the conversion product. To further enhance the technical effects of the present invention, the conversion product contains no more than 5 wt% (preferably no more than 1 wt%) of C7+ hydrocarbons, 0-50 wt% (preferably 10-40 wt%) of C5-C6 isoalkanes, 40-90 wt% (preferably 50-80 wt%) of C2-C6 n-alkanes, no more than 3 wt% (preferably no more than 1 wt%) of cyclic hydrocarbons, and has a sulfur content of 50-1000 mg / kg (preferably 100-200 mg / kg), based on a total weight of 100 wt% of the conversion product.

[0071] According to the technical solution of this application, the method further includes the following steps: separating the conversion product to obtain a separated stream mainly composed of C2-C6 n-alkanes (e.g., accounting for more than 80 wt%, 90 wt%, or 95 wt% of the total). Depending on the specific conversion rate, unreacted C5-C6 isoalkanes may also be obtained through this separation. The unreacted C5-C6 isoalkanes can be used as recycled material to continue the conversion reaction together with the feedstock hydrocarbons, thereby converting a higher proportion of C5-C6 isoalkanes into C2-C6 n-alkanes.

[0072] According to the technical solution of this application, the weight ratio of the separated material stream to the raw material hydrocarbon is 0.4-0.9:1 (preferably 0.5-0.8:1).

[0073] According to the technical solution of this invention, the method further includes the following steps: separating the conversion products to obtain a normal-carbon feed stream mainly composed of C4-C6 n-alkanes (e.g., accounting for more than 80 wt%, 90 wt%, or 95 wt% of the total) and / or a low-carbon feed stream mainly composed of C2-C3 hydrocarbons (e.g., accounting for more than 90 wt% or 95 wt% of the total). Depending on the specific conversion rate, unreacted C5-C6 isoalkanes may also be obtained through this separation. The unreacted C5-C6 isoalkanes can be used as recycled material to continue the conversion reaction together with the feedstock hydrocarbons, thereby converting a higher proportion of C5-C6 isoalkanes into C2-C6 n-alkanes.

[0074] According to the technical solution of this application, the conversion product, the separated feed stream, the normal feed stream, or the low-carbon feed stream exhibits high chemical activity compared to the feed hydrocarbon, and therefore can be advantageously used in chemical treatments such as steam cracking, alkane degassing, and hydrocracking to obtain high-value-added chemicals, preferably for steam cracking to produce ethylene.

[0075] According to the technical solution of this invention, ethylene-containing cracking products are obtained by steam cracking the conversion products, the separated feed stream, the ortho-form feed stream, or the low-carbon feed stream. According to this invention, the conversion products, the separated feed stream, the ortho-form feed stream, or the low-carbon feed stream are ideal ethylene cracking feedstocks, and the ethylene yield using these feedstocks is generally above 30 wt%, thus providing a high-value utilization pathway for low-value-added feedstock hydrocarbons in the prior art.

[0076] According to the technical solution of this application, the operating conditions for steam cracking include: a reaction temperature of 750-900℃, a reaction pressure of 0.1-0.5 MPaG, a water-to-oil mass ratio of 0.2-0.6, and a sulfur injection amount controlled to maintain a sulfur content of 100-200 mg / kg in the feedstock. According to this invention, since the conversion products, the separated feed stream, the ortho-form feed stream, or the low-carbon feed stream essentially retain all the sulfur contained in the sulfur-containing feedstock hydrocarbons, the sulfur injection requirement for steam cracking can be reduced by at least 50%. In the most preferred case, steam cracking can be completely free of additional sulfur injection; the sulfur contained in the conversion products, the separated feed stream, the ortho-form feed stream, or the low-carbon feed stream is sufficient to meet the steam cracking requirements.

[0077] According to the technical solution of this application, a conversion system for sulfur-containing feedstock hydrocarbons is also disclosed, comprising a feedstock hydrocarbon supply unit, a feedstock hydrocarbon conversion unit, and a steam cracking unit. According to the present invention, the system is specifically designed to implement the methods described above in this specification. Therefore, apart from the content explicitly stated in this paragraph, any content or matters not explicitly stated can be directly referred to the corresponding content or matters described above in relation to the methods, without any particular limitation.

[0078] The present invention will be further described below with reference to the accompanying drawings, but the present invention is not limited thereto.

[0079] according to Figure 1 The sulfur-containing raw material hydrocarbon 1 is mixed with hydrogen 2 and enters the hydroconversion reaction zone 3. The effluent 4 from the hydroconversion reaction zone enters the high-pressure separator 5. The separated gaseous stream 6 rich in hydrogen is recycled, and the liquid stream is used as ethylene feedstock.

[0080] according to Figure 2 The sulfur-containing raw material hydrocarbon 1 is mixed with hydrogen 2 and enters the hydroconversion reaction zone 3. The effluent 4 from the hydroconversion reaction zone enters the high-pressure separator 5. The separated gaseous stream 6 is recycled. The liquid stream 7 enters the fractionation tower to separate the gaseous product 9 as ethylene raw material. The liquid product 10 is recycled to the inlet of the hydroconversion reaction zone 3.

[0081] Example

[0082] The present invention will be further described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0083] In the following examples and comparative examples, the ethylene yield is calculated as a percentage of the ethylene production to the feed amount of the ethylene plant. The processing benefit per ton of oil refers to the revenue obtained from processing 1 ton of raw material, and is calculated as (ethylene product price - raw material and hydrogen price - processing energy consumption) / processing volume. The benchmark for the processing benefit per ton of oil is that the raw material is used directly as ethylene feedstock without undergoing hydrogenation conversion.

[0084] In the following examples and comparative examples, each hydroconversion catalyst is designated as Cat-A followed by a number, such as Cat-A1, Cat-A2, Cat-A3, etc. The hydroconversion catalysts were prepared using a conventional active metal saturation impregnation method, and the physicochemical properties of the obtained catalysts are shown in Table 1.

[0085] The preparation methods for Cat-A1 to Cat-A3 catalysts are as follows:

[0086] (1) Select mordenite with a SiO2 / Al2O3 molar ratio of 15 and mechanically mix it with a binder, shape it, dry it at 120°C for 10 hours, and calcine it at 500°C for 4 hours to prepare a catalyst support.

[0087] (2) The catalyst support obtained in step (1) containing active components is dried at 120°C for 10 hours and calcined at 500°C for 4 hours to prepare a hydrogenation conversion catalyst.

[0088] The preparation methods for Cat-A4 to Cat-A6 catalysts are as follows:

[0089] (1) Select ZSM-5 with a SiO2 / Al2O3 molar ratio of 10 and mechanically mix it with the binder, shape it, dry it at 120℃ for 10 hours, and calcine it at 500℃ for 4 hours to prepare a catalyst support.

[0090] (2) The catalyst support obtained in step (1) containing active components is dried at 120°C for 10 hours and calcined at 500°C for 4 hours to prepare a hydrogenation conversion catalyst.

[0091] The properties of the raw materials are shown in Table 2. Among them, raw material 5 requires isoparaffinic raw materials to be obtained through adsorption separation or distillation.

[0092] Table 1

[0093]

[0094] Table 2

[0095]

[0096] Example 1

[0097] The conversion method for sulfur-containing hydrocarbon feedstocks adopts, for example... Figure 1 The process includes:

[0098] (1) Raw material 1 is mixed with hydrogen and enters the hydroconversion reaction zone in sequence; the hydroconversion reaction zone is filled with hydroconversion catalyst Cat-A1;

[0099] (2) In step (1), the effluent from the hydrogenation reaction zone is separated into hydrogen-rich gas and liquid stream. The hydrogen-rich gas is recycled, and the liquid stream is used directly as ethylene feedstock. The process conditions and conversion results in this example are shown in Table 3.

[0100] In this example, approximately 47 wt% of the total C5-C6 isoalkanes were converted to C2-C6 n-alkanes. The weight ratio of the liquid stream to feedstock 1 was 0.34:1.

[0101] Example 2

[0102] The conversion method for sulfur-containing hydrocarbon feedstocks adopts, for example... Figure 1 The process includes:

[0103] (1) Raw material 1 is mixed with hydrogen and enters the hydroconversion reaction zone in sequence; the hydroconversion reaction zone is filled with hydroconversion catalyst Cat-A2;

[0104] (2) In step (1), the effluent from the hydrogenation reaction zone is separated into hydrogen-rich gas and liquid stream. The hydrogen-rich gas is recycled, and the liquid stream is used directly as ethylene feedstock. The process conditions and conversion results in this example are shown in Table 3.

[0105] In this example, approximately 38 wt% of the total C5-C6 isoalkanes were converted to C2-C6 n-alkanes. The weight ratio of the liquid stream to feedstock 1 was 0.54:1.

[0106] Example 3

[0107] The conversion method for sulfur-containing hydrocarbon feedstocks adopts, for example... Figure 1 The process includes:

[0108] (1) Raw material 1 is mixed with hydrogen and enters the hydroconversion reaction zone in sequence; the hydroconversion reaction zone is filled with hydroconversion catalyst Cat-A3;

[0109] (2) In step (1), the effluent from the hydrogenation reaction zone is separated into hydrogen-rich gas and liquid stream. The hydrogen-rich gas is recycled, and the liquid stream is used directly as ethylene feedstock. The process conditions and conversion results in this example are shown in Table 3.

[0110] In this example, approximately 31 wt% of the total C5-C6 isoalkanes were converted to C2-C6 n-alkanes. The weight ratio of the liquid stream to feedstock 1 was 0.63:1.

[0111] Example 4

[0112] The conversion method for sulfur-containing hydrocarbon feedstocks adopts, for example... Figure 1 The process includes:

[0113] (1) Raw material 1 is mixed with hydrogen and enters the hydroconversion reaction zone in sequence; the hydroconversion reaction zone is filled with hydroconversion catalyst Cat-A4;

[0114] (2) In step (1), the effluent from the hydrogenation reaction zone is separated into hydrogen-rich gas and liquid stream. The hydrogen-rich gas is recycled, and the liquid stream is used directly as ethylene feedstock. The process conditions and conversion results in this example are shown in Table 3.

[0115] In this example, approximately 59 wt% of the total C5-C6 isoalkanes were converted to C2-C6 n-alkanes. The weight ratio of the liquid stream to feedstock 1 was 0.18:1.

[0116] Example 5

[0117] The conversion method for sulfur-containing hydrocarbon feedstocks adopts, for example... Figure 1 The process includes:

[0118] (1) Raw material 1 is mixed with hydrogen and enters the hydroconversion reaction zone in sequence; the hydroconversion reaction zone is filled with hydroconversion catalyst Cat-A5;

[0119] (2) In step (1), the effluent from the hydrogenation reaction zone is separated into hydrogen-rich gas and liquid stream. The hydrogen-rich gas is recycled, and the liquid stream is used directly as ethylene feedstock. The process conditions and conversion results in this example are shown in Table 3.

[0120] In this example, approximately 53 wt% of the total C5-C6 isoalkanes were converted to C2-C6 n-alkanes. The weight ratio of the liquid stream to feedstock 1 was 0.26:1.

[0121] Example 6

[0122] The conversion method for sulfur-containing hydrocarbon feedstocks adopts, for example... Figure 1 The process includes:

[0123] (1) Raw material 1 is mixed with hydrogen and enters the hydroconversion reaction zone in sequence; the hydroconversion reaction zone is filled with hydroconversion catalyst Cat-A6;

[0124] (2) In step (1), the effluent from the hydrogenation reaction zone is separated into hydrogen-rich gas and liquid stream. The hydrogen-rich gas is recycled, and the liquid stream is used directly as ethylene feedstock. The process conditions and conversion results in this example are shown in Table 3.

[0125] In this example, approximately 46 wt% of the total C5-C6 isoalkanes were converted to C2-C6 n-alkanes. The weight ratio of the liquid stream to feedstock 1 was 0.35:1.

[0126] Example 7

[0127] The conversion method for sulfur-containing hydrocarbon feedstocks adopts, for example... Figure 2 The process includes:

[0128] (1) Raw material 1 is mixed with hydrogen and enters the hydroconversion reaction zone in sequence; the hydroconversion reaction zone is filled with hydroconversion catalyst Cat-A4;

[0129] (2) In step (1), the effluent from the hydroconversion reaction zone is separated into hydrogen-rich gas and liquid stream. The hydrogen-rich gas is recycled, and the C2 and C3 obtained from the liquid stream are used as ethylene feedstock. The remaining stream (referred to as the C4-C6 recycled stream) is cracked. The process conditions and conversion results in this example are shown in Table 3.

[0130] In this example, approximately 78 wt% of the total C5-C6 isoalkanes were converted to C2-C3 n-alkanes. The weight ratio of the C4-C6 recycled stream to feedstock 1 was 0.1:1.

[0131] Example 8

[0132] The conversion method for sulfur-containing hydrocarbon feedstocks adopts, for example... Figure 2 The process includes:

[0133] (1) Raw material 1 is mixed with hydrogen and enters the hydroconversion reaction zone in sequence; the hydroconversion reaction zone is filled with hydroconversion catalyst Cat-A5;

[0134] (2) In step (1), the effluent from the hydroconversion reaction zone is separated into hydrogen-rich gas and liquid stream. The hydrogen-rich gas is recycled, and the C2 and C3 obtained from the liquid stream are used as ethylene feedstock. C4-C6 are recycled for cracking. The process conditions and conversion results in this example are shown in Table 3.

[0135] In this example, approximately 78 wt% of the total C5-C6 isoalkanes were converted to C2-C3 n-alkanes. The weight ratio of the C4-C6 recycled stream to feedstock 1 was 0.2:1.

[0136] Example 9

[0137] The conversion method for sulfur-containing hydrocarbon feedstocks adopts, for example... Figure 2 The process includes:

[0138] (1) Raw material 1 is mixed with hydrogen and enters the hydroconversion reaction zone in sequence; the hydroconversion reaction zone is filled with hydroconversion catalyst Cat-A5;

[0139] (2) In step (1), the effluent from the hydroconversion reaction zone is separated into hydrogen-rich gas and liquid stream. The hydrogen-rich gas is recycled, and the C2 and C3 obtained from the liquid stream are used as ethylene feedstock. C4-C6 are recycled for cracking. The process conditions and conversion results in this example are shown in Table 3.

[0140] In this example, approximately 78 wt% of the total C5-C6 isoalkanes were converted to C2-C3 n-alkanes. The weight ratio of the C4-C6 recycled stream to feedstock 1 was 0.3:1.

[0141] Example 10

[0142] The conversion method for sulfur-containing hydrocarbon feedstocks adopts, for example... Figure 1 The process includes:

[0143] (1) Raw material 2 is mixed with hydrogen and enters the hydroconversion reaction zone in sequence; the hydroconversion reaction zone is filled with hydroconversion catalyst Cat-A1;

[0144] (2) In step (1), the effluent from the hydrogenation reaction zone is separated into hydrogen-rich gas and liquid stream. The hydrogen-rich gas is recycled, and the liquid stream is used directly as ethylene feedstock. The process conditions and conversion results in this example are shown in Table 3.

[0145] In this example, approximately 39 wt% of the total C5-C6 isoalkanes were converted to C2-C6 n-alkanes. The weight ratio of the liquid stream to feedstock 1 was 0.55:1.

[0146] Example 11

[0147] The conversion method for sulfur-containing hydrocarbon feedstocks adopts, for example... Figure 1 The process includes:

[0148] (1) Raw material 3 is mixed with hydrogen and enters the hydroconversion reaction zone in sequence; the hydroconversion reaction zone is filled with hydroconversion catalyst Cat-A4;

[0149] (2) In step (1), the effluent from the hydrogenation reaction zone is separated into hydrogen-rich gas and liquid stream. The hydrogen-rich gas is recycled, and the liquid stream is used directly as ethylene feedstock. The process conditions and conversion results in this example are shown in Table 3.

[0150] In this example, approximately 36 wt% of the total C5-C6 isoalkanes were converted to C2-C6 n-alkanes. The weight ratio of the liquid stream to feedstock 1 was 0.51:1.

[0151] Example 12

[0152] The conversion method for sulfur-containing hydrocarbon feedstocks adopts, for example... Figure 1 The process includes:

[0153] (1) Raw material 1 is mixed with hydrogen and enters the hydroconversion reaction zone in sequence; the hydroconversion reaction zone is filled with hydroconversion catalyst Cat-A1;

[0154] (2) In step (1), the effluent from the hydrogenation reaction zone is separated into hydrogen-rich gas and liquid stream. The hydrogen-rich gas is recycled, and the liquid stream is used directly as ethylene feedstock. The process conditions and conversion results in this example are shown in Table 3.

[0155] In this example, approximately 28 wt% of the total C5-C6 isoalkanes were converted to C2-C6 n-alkanes. The weight ratio of the liquid stream to feedstock 1 was 0.68:1.

[0156] Example 13

[0157] The conversion method for sulfur-containing hydrocarbon feedstocks adopts, for example... Figure 1 The process includes:

[0158] (1) Raw material 7 is mixed with hydrogen and enters the hydroconversion reaction zone in sequence; the hydroconversion reaction zone is filled with hydroconversion catalyst Cat-A1;

[0159] (2) In step (1), the effluent from the hydrogenation reaction zone is separated into hydrogen-rich gas and liquid stream. The hydrogen-rich gas is recycled, and the liquid stream is used directly as ethylene feedstock. The process conditions and conversion results in this example are shown in Table 3.

[0160] In this example, approximately 47 wt% of the total C5-C6 isoalkanes were converted to C2-C6 n-alkanes. The weight ratio of the liquid stream to feedstock 1 was 0.34:1.

[0161] Example 14

[0162] The conversion method for sulfur-containing hydrocarbon feedstocks adopts, for example... Figure 1 The process includes:

[0163] (1) Raw material 8 is mixed with hydrogen and enters the hydroconversion reaction zone in sequence; the hydroconversion reaction zone is filled with hydroconversion catalyst Cat-A1;

[0164] (2) In step (1), the effluent from the hydrogenation reaction zone is separated into hydrogen-rich gas and liquid stream. The hydrogen-rich gas is recycled, and the liquid stream is used directly as ethylene feedstock. The process conditions and conversion results in this example are shown in Table 3.

[0165] In this example, approximately 47 wt% of the total C5-C6 isoalkanes were converted to C2-C6 n-alkanes. The weight ratio of the liquid stream to feedstock 1 was 0.34:1.

[0166] Comparative Example 1

[0167] The conversion method of raw material hydrocarbons adopts, for example... Figure 1 The process includes:

[0168] (1) Raw material 4 is mixed with hydrogen and enters the hydroconversion reaction zone in sequence; the hydroconversion reaction zone is filled with hydroconversion catalyst Cat-A1;

[0169] (2) In step (1), the effluent from the hydrogenation reaction zone is separated into hydrogen-rich gas and liquid stream. The hydrogen-rich gas is recycled, and the liquid stream is used directly as ethylene feedstock. The process conditions and conversion results in this example are shown in Table 3.

[0170] Comparative Example 2

[0171] The conversion method of raw material hydrocarbons adopts, for example... Figure 1 The process includes:

[0172] (1) Raw material 4 is mixed with hydrogen and enters the hydroconversion reaction zone in sequence; the hydroconversion reaction zone is filled with hydroconversion catalyst Cat-A4;

[0173] (2) In step (1), the effluent from the hydrogenation reaction zone is separated into hydrogen-rich gas and liquid stream. The hydrogen-rich gas is recycled, and the liquid stream is used directly as ethylene feedstock. The process conditions and conversion results in this example are shown in Table 3.

[0174] Comparative Example 3

[0175] The conversion method of raw material hydrocarbons adopts, for example... Figure 1 The process includes:

[0176] (1) Raw material 5 is mixed with hydrogen and enters the hydroconversion reaction zone in sequence; the hydroconversion reaction zone is filled with hydroconversion catalyst Cat-A1;

[0177] (2) In step (1), the effluent from the hydrogenation reaction zone is separated into hydrogen-rich gas and liquid stream. The hydrogen-rich gas is recycled, and the liquid stream is used directly as ethylene feedstock. The process conditions and conversion results in this example are shown in Table 3.

[0178] Comparative Example 4

[0179] The conversion method of raw material hydrocarbons adopts, for example... Figure 1 The process includes:

[0180] (1) Raw material 5 is mixed with hydrogen and enters the hydroconversion reaction zone in sequence; the hydroconversion reaction zone is filled with hydroconversion catalyst Cat-A4;

[0181] (2) In step (1), the effluent from the hydrogenation reaction zone is separated into hydrogen-rich gas and liquid stream. The hydrogen-rich gas is recycled, and the liquid stream is used directly as ethylene feedstock. The process conditions and conversion results in this example are shown in Table 3.

[0182] Comparative Example 5

[0183] The conversion method of raw material hydrocarbons adopts, for example... Figure 1 The process includes:

[0184] (1) Raw material 6 is mixed with hydrogen and enters the hydroconversion reaction zone in sequence; the hydroconversion reaction zone is filled with hydroconversion catalyst Cat-A1;

[0185] (2) In step (1), the effluent from the hydrogenation reaction zone is separated into hydrogen-rich gas and liquid stream. The hydrogen-rich gas is recycled, and the liquid stream is used directly as ethylene feedstock. The process conditions and conversion results in this example are shown in Table 3.

[0186] Table 3 Conversion Results

[0187]

[0188] Continued from Table 3: Conversion Results

[0189]

[0190] Continued from Table 3: Conversion Results

[0191]

[0192] Continued from Table 3: Conversion Results

[0193]

[0194] By comparison, it can be seen that the method of the present invention can effectively convert sulfides in raw materials into hydrogen sulfide and selectively retain them in the conversion product. When the conversion product is used as ethylene feedstock, the amount of sulfur injection can be reduced or even eliminated, realizing the high-value utilization of worthless components.

Claims

1. A method for converting sulfur-containing hydrocarbon feedstock, comprising the following steps: 1) Provide sulfur-containing feedstock hydrocarbons, wherein the sulfur content of the sulfur-containing feedstock hydrocarbons is 50-5000 mg / kg, and the sulfur-containing feedstock hydrocarbons contain C5-C6 isoalkanes relative to the total weight of the sulfur-containing feedstock hydrocarbons, and the content of the C5-C6 isoalkanes is 50 wt% or more, based on a total weight of the sulfur-containing feedstock hydrocarbons of 100 wt%. 2) Chemically convert the sulfur-containing raw material hydrocarbons to obtain sulfur-containing conversion products, wherein the chemical conversion involves reacting more than 30 wt% of the C5-C6 isoalkanes in the presence of hydrogen, and the conversion products contain C2-C6 n-alkanes, and the sulfur content of the conversion products is 50-1000 mg / kg. The method further includes the following steps: Optionally, the conversion products can be separated to obtain a separated stream containing more than 80 wt% C2-C6 n-alkanes, or optionally, a n-alkanes stream containing more than 80 wt% C4-C6 n-alkanes or a low-carbon stream containing more than 90 wt% C2-C3 hydrocarbons. Steam cracking of the conversion products, the separated feed stream, the ortho-form feed stream, or the low-carbon feed stream yields cracking products containing ethylene.

2. The conversion method according to claim 1, wherein the sulfur content of the sulfur-containing raw material hydrocarbon is 200-1000 mg / kg.

3. The conversion method according to claim 1, wherein the sulfur-containing raw material hydrocarbon contains C5-C6 isoalkanes, the chemical conversion is to cause more than 90 wt% of the C5-C6 isoalkanes to undergo a conversion reaction in the presence of hydrogen, and the conversion product contains C2-C6 n-alkanes.

4. The conversion method according to claim 1, wherein the initial boiling point of the sulfur-containing feedstock hydrocarbon is 10-30℃ and the final boiling point is 50-100℃.

5. The conversion method according to claim 1, wherein the initial boiling point of the sulfur-containing feedstock hydrocarbon is 15-25°C and the final boiling point is 55-70°C.

6. The conversion method according to claim 1, wherein the sulfur-containing raw material hydrocarbon contains 0-10 wt% C7+ hydrocarbons, 50 wt% or more C5-C6 isoalkanes, 10-30 wt% C5-C6 n-alkanes, 0-10 wt% C4- hydrocarbons, and 1-10 wt% cyclic hydrocarbons, based on a total weight of 100 wt% of the sulfur-containing raw material hydrocarbons.

7. The conversion method according to claim 1, wherein the content of C7+ hydrocarbons in the conversion product is not higher than 5 wt%, the content of C5-C6 isoalkanes is 0-50 wt%, the content of C2-C6 n-alkanes is 40-90 wt%, the content of cyclic hydrocarbons is not higher than 3 wt%, and the sulfur content is 100-200 mg / kg, based on the total weight of the conversion product being 100 wt%.

8. The conversion method according to claim 1, wherein the sulfur-containing raw material hydrocarbon contains 0.5-5 wt% C7+ hydrocarbons, 70-80 wt% C5-C6 isoalkanes, 15-25 wt% C5-C6 n-alkanes, 2-5 wt% C4- hydrocarbons, and 2-5 wt% cyclic hydrocarbons, based on a total weight of 100 wt% of the sulfur-containing raw material hydrocarbons.

9. The conversion method according to claim 1, wherein the content of C7+ hydrocarbons in the conversion product is not higher than 1 wt%, the content of C5-C6 isoalkanes is 10-40 wt%, the content of C2-C6 n-alkanes is 50-80 wt%, and the content of cyclic hydrocarbons is not higher than 1 wt%, based on a total weight of 100 wt% of the conversion product.

10. The conversion method of claim 1, wherein the conversion process is carried out in the presence of a catalyst, and the catalyst comprises a molecular sieve and an active metal component.

11. The conversion method of claim 10, wherein the molecular sieve is a molecular sieve with shape-selective catalytic properties and is selected from one or more of mordenite, ZSM molecular sieve, SAPO molecular sieve and EU-1 molecular sieve.

12. The conversion method of claim 10, wherein the molecular sieve is one or more selected from mordenite and ZSM molecular sieve.

13. The conversion method of claim 10, wherein the molecular sieve is selected from one or more of mordenite, ZSM-5 molecular sieve, ZSM-11 molecular sieve, ZSM-12 molecular sieve, ZSM-22 molecular sieve, ZSM-23 molecular sieve, ZSM-35 molecular sieve, Beta molecular sieve and ZSM-38 molecular sieve.

14. The conversion method of claim 10, wherein the catalyst further comprises a binder, and the content of the binder is 5-65 wt% based on the weight of the catalyst.

15. The conversion method of claim 10, wherein the active metal component is selected from at least one of Group VIB metals and Group VIII non-noble metals, wherein the Group VIB metal is molybdenum and / or tungsten, and the Group VIII non-noble metal is cobalt and / or nickel.

16. The conversion method of claim 15, wherein, based on the weight of the catalyst, the content of the Group VIB metal as oxide is 5.0-30.0 wt%, and the content of the Group VIII non-precious metal as oxide is 0.5-15.0 wt%.

17. The conversion method of claim 15, wherein, based on the weight of the catalyst, the content of the Group VIB metal as oxide is 10-20 wt%, and the content of the Group VIII non-precious metal as oxide is 3-10 wt%.

18. The conversion method of claim 10, wherein the content of the molecular sieve is 30-80 wt% based on the weight of the catalyst.

19. The conversion method of claim 10, wherein the content of the molecular sieve is 40-70 wt% based on the weight of the catalyst.

20. The conversion method according to claim 1, wherein the reaction conditions of the conversion reaction include: The reaction pressure was 0.5-10.0 MPaG, the reaction temperature was 250-500℃, and the liquid hourly space velocity was 0.1-15.0 h⁻¹. -1 The hydrogen-to-oil volume ratio is 10:1-2500:

1.

21. The conversion method according to claim 1, wherein the reaction conditions for the conversion reaction include: The reaction pressure was 2.0-5.0 MPaG, the reaction temperature was 350-450℃, and the liquid hourly space velocity was 0.5-5.0 h⁻¹. -1 The hydrogen-to-oil volume ratio is 100:1-1000:

1.

22. The conversion method according to claim 1, wherein, The C2-C6 n-alkanes in the separated feed stream account for more than 95 wt% of the total content.

23. The conversion method according to claim 1, wherein, The content of C4-C6 n-alkanes in the n-alkane stream is more than 95 wt% of the total.

24. The conversion method according to claim 1, wherein, The low-carbon feed stream contains more than 95 wt% C2-C3 hydrocarbons.

25. The conversion method of claim 1, wherein the weight ratio of the separated feed stream to the raw material hydrocarbon is 0.4-0.9:

1.

26. The conversion method of claim 1, wherein the weight ratio of the separated feed stream to the raw material hydrocarbon is 0.5-0.8:

1.

27. The conversion method of claim 1, wherein the operating conditions for the steam cracking include: The reaction temperature is 750-900℃, the reaction pressure is 0.1-0.5MPaG, the water-oil mass ratio is 0.2-0.6, and the sulfur content of the system is 100-200mg / kg.

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