A method and apparatus for the combined preparation of olefins and aromatics from hydrocarbons.

Abstract

This invention discloses a method and apparatus for the joint preparation of olefins and aromatics from hydrocarbons. The method includes: subjecting atomized feedstock oil to a preliminary cracking reaction under the action of a catalyst to obtain preliminary cracked gas and a catalyst to be generated; performing a first fractionation on the preliminary cracked gas to obtain low-carbon olefins and a heavy fraction; subjecting the atomized heavy fraction to a cyclic cracking reaction under the action of a catalyst to obtain cyclic cracked gas and a catalyst to be generated; and performing a second fractionation on the cyclic cracked gas to obtain low-carbon olefins and low-carbon aromatics. Both the preliminary cracking reaction and the cyclic cracking reaction are carried out in a circulating fluidized bed or riser. In this invention, the preliminary cracking reaction and the cyclic cracking reaction are both tandem reactions, which can significantly improve the yield of low-carbon olefins and low-carbon aromatics, extend catalyst life, reduce operating costs, and ensure long-term stable operation of the equipment.

Description

Technical Field

[0001] This application relates to the field of chemical technology, and more specifically, to a method and apparatus for the combined preparation of olefins and aromatics from hydrocarbons. Background Technology

[0002] Low-carbon olefins (such as ethylene, propylene, butene, and butadiene) and light aromatics (benzene, toluene, and xylene) are core intermediates in the petrochemical industry, hailed as the "cornerstone of the petrochemical industry." Their industrial production mainly relies on two technological routes: one is the steam pyrolysis process using light hydrocarbons (ethane, naphtha, etc.) as feedstock, and the other is the catalytic cracking process using heavy oil as feedstock. Both processes must be carried out in an oxygen-free environment with steam present. Typical feedstocks for steam pyrolysis include gaseous light alkanes such as ethane and propane, as well as liquid feedstocks such as naphtha and hydrotreated tail oil.

[0003] However, traditional steam pyrolysis processes have significant technical limitations: First, the product distribution lacks flexibility. For example, although the ethylene yield from ethane steam pyrolysis can reach over 80%, the yields of propylene, butene, and high-value aromatics are extremely low, making it difficult to adapt to dynamic changes in market demand. Second, although liquid feedstocks such as naphtha can achieve a balanced production of olefins and aromatics, the reaction requires maintaining extremely high temperatures, resulting in high energy consumption. Furthermore, the product distribution is constrained by thermodynamic equilibrium, limiting the potential for increasing the yield of the target product. Third, high-quality raw material resources are scarce and their prices fluctuate wildly, seriously affecting the stable operation of downstream chemical industries.

[0004] To address the demand for aromatics production from naphtha feedstock, the industry has developed mature integrated aromatics production units. The core process comprises three key steps: the first is catalytic reforming, which converts naphtha into aromatic-rich reformate through a reaction; the second is aromatics extraction, utilizing the selective solubility of solvents to achieve precise separation of aromatics from non-aromatics; and the third is xylene separation and conversion, using a closed-loop system consisting of para-xylene fractionation, shape-selective adsorption separation, and isomerization to continuously convert and purify mixed C8 aromatics into para-xylene, the product with the highest market demand. While this technology is mature and reliable, its performance and economic benefits are highly dependent on high-quality naphtha feedstock, limiting its application in a wider range of feedstock systems.

[0005] Therefore, readily available and inexpensive heavy feedstocks (especially straight-run gasoline and diesel and secondary processed low-quality gasoline and diesel) have become a highly attractive alternative route for the production of low-carbon olefins and aromatics. Using heavy feedstocks to produce low-carbon olefins and aromatics enables integrated refining and chemical operations, representing an effective technological choice for maximizing the value of heavy oil. However, it should be noted that direct steam pyrolysis of heavy gasoline and diesel can easily lead to severe coking in the cracking furnace tubes, resulting in low product yields when cracking gasoline and diesel to produce olefins and aromatics, and the unit cannot operate stably for extended periods.

[0006] Therefore, this application is hereby submitted. Summary of the Invention

[0007] The purpose of this invention is to provide a method and apparatus for the combined preparation of olefins and aromatics from hydrocarbons, overcoming the technical deficiency of existing technologies that can only produce olefins or aromatics at a time, but this invention can produce olefins and aromatics simultaneously.

[0008] The raw materials for this invention are abundant. Naphtha, gasoline, or light diesel oil, as long as the carbon number is between 4 and 20, can be used as raw materials for the production of olefins and aromatics in this invention.

[0009] Furthermore, the raw materials required for this invention do not require desulfurization and refining, and the sulfur content of the raw materials is basically not limited. Undesulfurized catalytic gasoline can be used as its raw material. It does not require the use of raw materials with ultra-low sulfur content as in catalytic reforming, and the reaction process is harsh. Therefore, this technology is advanced.

[0010] The method of the present invention does not require aromatic extraction of aromatic hydrocarbons. The non-aromatic content in the mixed aromatic hydrocarbons after distillation directly meets the separation requirements. Benzene, toluene, and xylene with qualified content can be separated by simple direct distillation.

[0011] This application is implemented as follows: In a first aspect, this application provides a method for the combined preparation of olefins and aromatics from hydrocarbons, comprising: The atomized feed oil undergoes a preliminary cracking reaction under the action of a catalyst to obtain preliminary cracked gas and catalyst to be generated; The preliminary cracked gas is subjected to a first fractionation to obtain low-carbon olefins and heavy fractions; The atomized heavy fraction is subjected to a cyclic pyrolysis reaction under the action of a catalyst to obtain cyclic pyrolysis gas and catalyst to be generated; The recycled cracked gas is subjected to a second fractionation to obtain low-carbon olefins and low-carbon aromatics. The initial pyrolysis reaction and the cyclic pyrolysis reaction are both carried out in a circulating fluidized bed or a riser.

[0012] In an optional embodiment, the feedstock oil is a hydrocarbon with a carbon number in the range of 4-20, including but not limited to at least one of naphtha, gasoline, and light diesel oil, and does not require desulfurization refining.

[0013] In an optional embodiment, the catalyst is selected from at least one of ZSM-5 molecular sieve, rare earth-Y molecular sieve, ultrastable Y molecular sieve, X-type molecular sieve, basic solid porous catalyst and β molecular sieve catalyst.

[0014] In an optional embodiment, the temperature of the preliminary pyrolysis reaction is 450℃-650℃, and the agent-to-oil ratio of the preliminary pyrolysis reaction is 1-50:1.

[0015] In an optional embodiment, the temperature of the catalyst in the preliminary pyrolysis reaction is 650°C-1000°C; And / or, the temperature of the raw material oil before atomization is 100-500℃; And / or, in the first fractionation step, the temperature at the top of the fractionation column is 50-200℃, the temperature at the bottom of the column is 100-300℃, and the pressure at the top of the column is 0-2 MPa.

[0016] In an optional embodiment, the temperature of the cyclic pyrolysis reaction is 500℃-800℃, and the agent-to-oil ratio of the cyclic pyrolysis reaction is 1-50:1.

[0017] In an optional embodiment, the temperature of the catalyst in the cyclic pyrolysis reaction is 600°C-850°C; And / or, the temperature of the heavy fraction before atomization is 100-500℃; And / or, in the second fractionation step, the top temperature of the fractionation column is 50-200℃, the bottom temperature is 100-300℃, and the top pressure is 0-2 MPa; after fractionation, the low-carbon aromatics do not require aromatic extraction and can be separated into benzene, toluene, and xylene by direct distillation.

[0018] In an optional embodiment, the catalyst is further regenerated at a temperature of 580°C-1000°C in an oxidizing atmosphere containing oxygen.

[0019] Secondly, this application provides an apparatus for the method of jointly preparing olefins and aromatics from hydrocarbons as described in any of the foregoing embodiments, including a pyrolyzer one and a pyrolyzer two; The reactant inlet of the first pyrolysis unit is connected to a feedstock oil storage tank. The initial pyrolysis gas outlet of the first pyrolysis unit is sequentially connected to a first gas-liquid fractionation tower, a regenerator, and a dry gas storage tank. The C5+ component outlet of the first gas-liquid fractionation tower is connected to an intermediate tank. The total fraction outlet of the intermediate tank is connected to the reactant inlet of the second pyrolysis unit. The circulating pyrolysis gas outlet of the second pyrolyzer is sequentially connected to a regenerator and a second gas-liquid fractionation tower.

[0020] In an optional embodiment, a catalyst regenerator is also included, wherein the catalyst inlet of the catalyst regenerator is connected to the solid phase outlet of the first pyrolyzer and the second pyrolyzer, respectively.

[0021] This application has the following beneficial effects: The method provided in this application enables the combined production of olefins and aromatics in the same system, overcoming the limitation of existing technologies that typically only allow for single-product production. This method offers strong feedstock adaptability, a wide carbon number range (C4-C20), and eliminates the need for pre-desulfurization and purification, reducing feedstock pretreatment costs and complexity. The combination of two-stage riser cracking and fractionation optimizes product distribution; aromatic products do not require complex extraction processes and can be directly obtained as qualified benzene, toluene, and xylene products through simple distillation. The entire process is carried out within a fluidized bed catalytic cracking system, improving the yield of low-carbon olefins and aromatics, achieving efficient catalyst recycling and regeneration, which is beneficial for long-term stable operation of the unit and reduces operating costs. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a flowchart for the combined preparation of olefins and aromatics from hydrocarbons.

[0024] Diagram: 1-Feed oil storage tank, 2-Feed oil and gas outlet, 3-Cracker I, 4-Preliminary cracked gas outlet, 5-First gas-liquid fractionation tower, 6-First fractionation tower, 7-Olefin storage tank, 8-Dry gas storage tank, 9-Regenerator, 10-C5+ component outlet I, 11-Intermediate tank, 12-Cracker II, 13-Second gas-liquid fractionation tower, 14-C5+ component outlet II, 15-Liquid storage tank, 16-Second fractionation tower, 17-C5 component outlet, 18-Benzene removal tower, 19-Benzene storage tank, 20-Toluene removal tower, 21-Toluene storage tank, 22-Xylene removal tower, 23-Xylene storage tank, 24-C9+ component outlet, 25-C3-C4 liquid alkane outlet, 26-First regenerated catalyst outlet; 27-Second regenerated catalyst outlet, 28-Total fraction outlet. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0026] This application provides a method for the combined preparation of olefins and aromatics from hydrocarbons, comprising: The atomized feed oil undergoes a preliminary cracking reaction under the action of a catalyst to obtain preliminary cracked gas and catalyst to be generated; The preliminary cracked gas is subjected to a first fractionation to obtain low-carbon olefins and heavy fractions; The atomized heavy fraction is subjected to a cyclic pyrolysis reaction under the action of a catalyst to obtain cyclic pyrolysis gas and catalyst to be generated; The recycled cracked gas is subjected to a second fractionation to obtain low-carbon olefins and low-carbon aromatics. The initial pyrolysis reaction and the cyclic pyrolysis reaction are both carried out in a circulating fluidized bed or a pyrolysis reactor.

[0027] This application achieves the co-production of olefins and aromatics within the FCC framework through the coupling of two-stage cracking reactions and fractionation, overcoming the limitations of traditional technologies that can only produce one type of product. The system relies on a highly efficient continuous catalyst regeneration mechanism to promptly separate and regenerate coking catalysts, significantly improving the yields of low-carbon olefins and aromatics, while extending catalyst life, reducing operating costs, and ensuring long-term stable operation of the unit.

[0028] In an optional embodiment, the feedstock is a liquid hydrocarbon with a carbon number between 4 and 20, including but not limited to at least one of naphtha, gasoline, and light diesel oil. The feedstock does not require desulfurization refining, and its sulfur content is essentially unrestricted. It can directly use feedstocks such as undesulfurized catalytic gasoline. Compared to processes such as catalytic reforming that require ultra-low sulfur feedstocks, it exhibits significant feedstock adaptability and techno-economic advantages.

[0029] In an optional embodiment, the catalyst is selected from at least one of ZSM-5 molecular sieves, rare earth-Y molecular sieves, ultrastable Y molecular sieves, X-type molecular sieves, basic solid porous catalysts, and β-molecular sieve catalysts. By selecting a suitable catalyst, the selectivity of the target product can be effectively improved.

[0030] In an optional embodiment, the temperature of the preliminary pyrolysis reaction is 450℃-650℃, and the agent-to-oil ratio of the preliminary pyrolysis reaction is 1-50:1. The temperature of the preliminary pyrolysis reaction is the outlet temperature of the pyrolysis reactor.

[0031] In an optional embodiment, the temperature of the catalyst in the preliminary pyrolysis reaction is 650°C-1000°C; And / or, the temperature of the raw material oil before atomization is 100-500℃; And / or, in the first fractionation step, the temperature at the top of the gas-liquid fractionation column is 50-200℃, the temperature at the bottom of the column is 100-300℃, and the pressure at the top of the column is 0-2 MPa.

[0032] In an optional embodiment, the temperature of the cyclic pyrolysis reaction is 550℃-800℃, and the agent-to-oil ratio of the cyclic pyrolysis reaction is 1-50:1. The temperature of the cyclic pyrolysis reaction is the outlet temperature of the pyrolysis reactor.

[0033] In an optional embodiment, the temperature of the catalyst in the cyclic pyrolysis reaction is 600°C-850°C; And / or, the temperature of the heavy fraction before atomization is 100-500℃; And / or, in the second fractionation step, the temperature at the top of the fractionation column is 50-200℃, the temperature at the bottom of the column is 100-300℃, and the pressure at the top of the column is 0-2 MPa; the low-carbon aromatic products obtained by this fractionation have non-aromatic content that can directly meet the separation requirements, so there is no need for a complicated aromatic extraction process, and benzene, toluene, and xylene with qualified content can be separated by conventional distillation.

[0034] In an optional embodiment, the catalyst is also regenerated at a temperature of 580°C-1000°C in an oxidizing atmosphere containing oxygen. By adjusting the regeneration conditions, the reaction process can be optimized.

[0035] In this application, both the initial cracking reaction and the cyclic cracking reaction are carried out in the cracking reactor of the fluidized catalytic cracking (FCC) reactor. The continuous catalyst regeneration system in the FCC reactor can promptly separate the coked and deactivated catalyst during the reaction process and regenerate the separated catalyst in a timely manner, which can effectively extend the service life of the catalyst and ensure the long-term stable operation of the unit. This method is suitable for large-scale industrial production.

[0036] Furthermore, by adjusting the catalyst regeneration temperature and combining it with a rapid fluidized bed reactor to increase the catalyst-to-oil ratio, the reaction process can be precisely controlled, significantly improving the yield of the target product.

[0037] This application also provides an apparatus for the method of jointly preparing olefins and aromatics from hydrocarbons as described in any of the foregoing embodiments, such as... Figure 1 As shown, it includes pyrolyzer 1 (3) and pyrolyzer 2 (12); The reactant inlet of the pyrolysis unit 3 is connected to the feed oil storage tank 1. The initial pyrolysis gas outlet 4 of the pyrolysis unit 3 is sequentially connected to the first gas-liquid fractionation tower 5, the first fractionation tower 6, and the low-carbon olefin storage tank 7. The C5+ component outlet 10 of the first gas-liquid fractionation tower 5 is connected to the intermediate tank 11. The total fraction outlet 28 of the intermediate tank 11 is connected to the reactant inlet of the pyrolysis unit 2 12. The circulating pyrolysis gas outlet of the second pyrolysis unit 12 is sequentially connected to a second gas-liquid fractionation tower 13, a liquid storage tank 15, and a second fractionation tower 16.

[0038] In an optional embodiment, a catalyst regenerator 9 is also included. The catalyst inlet of the catalyst regenerator 9 is connected to the solid phase outlet of the first pyrolyzer 3 and the second pyrolyzer 12, respectively, and the regenerated catalyst outlet of the catalyst regenerator 9 is connected to the catalyst inlet of the second pyrolyzer 12 and the first pyrolyzer 3, respectively.

[0039] In some implementation methods, the specific workflow for the combined preparation of olefins and aromatics from hydrocarbons is as follows: (1) The raw material oil, such as the gasoline and diesel mixture, enters the preheater through the raw material oil outlet 2 in the raw material oil storage tank 1 and is heated to 100-500℃. The raw material oil outlet 2 is then sprayed into the upper part of the cracker 3 by the high-efficiency atomizing nozzle, and comes into millisecond contact with the high-temperature catalyst solid at 650℃-1000℃, where heating, vaporization and preliminary cracking reactions occur. The reaction temperature is 450℃-650℃. After the reaction, the catalyst solid enters the regenerator 9 for regeneration reaction. (2) The preliminary cracked gas enters the first gas-liquid fractionator 5 directly without condensation for separation. The C5+ component enters the intermediate tank 11, and the gas enters the first fractionation tower 6 for separation. The separated low-carbon olefins (such as ethylene, propylene, and butene) are collected in the olefin storage tank 7, and the separated dry gas (H2-methane-ethane) is collected in the dry gas storage tank 8. The C3-C4 liquid alkanes condensed after olefin separation enter the intermediate tank 11 for temporary storage through the C3-C4 liquid alkanes outlet 25. (3) The catalyst to be generated in the first 3 and the catalyst to be generated in the second 12 enter the lower part of the regenerator 9 to undergo a regeneration reaction. The regeneration reaction temperature is 580℃-1000℃. The regenerated high-temperature solid catalyst flows into the riser pipes of the first 3 and the second 12 of the pyrolyzer in a certain proportion after being returned to the first regenerated catalyst outlet 26 and the second regenerated catalyst outlet 27 to participate in the reaction. (4) The heavy fraction separated from the first gas-liquid fractionation tower 5 enters the intermediate tank 11 for temporary storage, and then enters the second cracker 12 to contact the catalyst at 600℃-850℃, and undergoes a cyclic cracking reaction at 500℃-800℃. The reaction products are cyclically cracked, and the spent catalyst after the reaction enters the regenerator 9 for regeneration reaction. The products enter the second gas-liquid fractionation tower 13 for separation. The liquid discharged from the second outlet 14 of C5+ component enters the liquid storage tank 15 for further separation, and the gas enters the first fractionation tower 6 for separation. The separated low carbon olefins (such as ethylene, propylene, butene) are collected in the olefin storage tank 7, and the separated dry gas (H2-methane-ethane) is collected in the dry gas storage tank 8. The C3-C4 liquid alkanes condensed after the separation of olefins enter the intermediate tank 11 for temporary storage. (5) The liquid entering the liquid storage tank 15 enters the second fractionation tower 16 for separation. The obtained low-carbon aromatics are successively fractionated through the benzene removal tower 18, the toluene removal tower 20 and the xylene removal tower 22. The products obtained are collected by the benzene storage tank 19, the toluene storage tank 21 and the xylene storage tank 23 respectively. The heavy fraction enters the intermediate tank 11 through the C5 component outlet 17 to continue to participate in the recycling reaction. The remaining material in the xylene removal tower 22 enters the intermediate tank 11 through the C9+ component outlet 24 to continue to participate in the recycling reaction.

[0040] (6) Yield calculation and data analysis First cleavage reaction: Conversion rate (X1) = (1 - mass of unreacted raw material / total feed mass) × 100%; Low-carbon olefin yield = (total mass of low-carbon olefins produced / total mass of feedstock entering the reactor) × 100%; Hydrogen yield: (mass of hydrogen produced / total mass of feedstock entering the reactor) × 100%; Second cleavage reaction: Conversion rate (X2) = [1 - (mass of unreacted recycled feed / total mass of recycled feed entering the reactor)] × 100%; Note: "Recycled feed" here refers to the mixture of heavy fraction from the intermediate tank and gasoline raffinate.

[0041] Low-carbon olefin yield = (total mass of low-carbon olefins produced / total mass of feedstock entering the reactor) × 100%; Aromatic hydrocarbon yield = (total mass of low-carbon aromatic hydrocarbons generated / total mass of circulating feed entering the reactor) × 100%; Hydrogen yield = (mass of hydrogen generated / total mass of circulating feed entering the reactor) × 100%.

[0042] The features and performance of this application will be further described in detail below with reference to the embodiments.

[0043] Example 1: This embodiment provides a method for the combined preparation of olefins and aromatics from hydrocarbons, specifically including the following steps: Liquid hydrocarbon feedstock (C9+ mixed oil) with carbon numbers 4-20 is released from feedstock storage tank 1. The mixed oil and gas is preheated to 400℃ by a preheater, and then injected into cracker 3 using a high-efficiency atomizing nozzle. The oil mist comes into millisecond contact with the ZSM-5 catalyst and is further mixed and heated, undergoing a preliminary thermal cracking reaction at 650℃. The resulting C9+ mixed oil has a conversion rate of 55%, a low-carbon olefin yield of 35.5%, and a dry gas yield of 5.5%. The spent catalyst enters regenerator 9 and undergoes a regeneration reaction with a regenerating agent at 700℃. The regenerated catalyst material is returned to cracker 3 via a return controller at a catalyst-to-oil ratio of 20 to continue circulating and cracking the mixed oil and gas. The high-temperature mixed oil and gas after the reaction enters the first fractionation tower 6 for component separation. The top temperature of the fractionation tower is 100℃, the bottom temperature is 300℃, and the top pressure is 0.2℃. At MPa, the cracked gas is separated to obtain low-carbon olefins such as ethylene, propylene, and butene, which are output as products through the olefin mixture outlet into the olefin storage tank 7. The intermediate heavy fraction is mixed with recycle oil and slurry oil and passed through intermediate tank 11. After being heated by a preheater, it is used as feedstock in cracker 2 12 and mixed with the regenerated cracking catalyst returned from regenerator 9 (catalyst-to-oil ratio of 25). A cyclic cracking reaction is carried out at 800°C, and the feedstock conversion rate is 90%, the low-carbon olefin yield is 29.5%, the aromatics yield is 67.5%, and the dry gas yield is 3%. After the reaction, the mixed oil and gas and the spent catalyst are subjected to gas-solid separation. The coked spent catalyst is fed into regenerator 9 after flow control and undergoes a regeneration reaction with regenerator oxygen at 650°C. The regenerated catalyst material is returned to cracker 1 3 / cracker 2 12 through the return controller at a catalyst-to-oil ratio of 20 to continue the process. The oil and gas are mixed with circulating and cracked oil and gas. After cracking again, the oil and gas directly enter the second gas-liquid fractionation tower 13 without condensation. The temperature at the top of the fractionation tower is 150°C, the temperature at the bottom of the tower is 280°C, and the pressure at the top of the tower is 0.5 MPa. The products are separated into different fractions. The cracked gas is separated to obtain low-carbon olefins such as ethylene, propylene, and butene, which are output as products into the olefin storage tank through the low-carbon olefin outlet. The gasoline fraction is separated after passing through the fractionation tower to obtain low-carbon aromatics such as benzene, toluene, and xylene. The non-aromatic content of these aromatics already meets the product specifications, and no aromatic extraction is required. Finally, the method in this embodiment achieves a total yield of about 16.7% for low-carbon olefins, a total yield of about 78.5% for low-carbon aromatics, and a total dry gas yield of about 4.8%. It realizes the efficient joint production of olefins and aromatics, and has strong raw material adaptability, does not require desulfurization pretreatment, and the aromatic products such as benzene, toluene, and xylene can be obtained directly through simple fractionation.

[0044] Example 2: This embodiment provides a method for the combined preparation of olefins and aromatics from hydrocarbons, specifically including the following steps: Liquid hydrocarbon feedstock (a mixture of gasoline and diesel) with C4-20 carbon atoms is released from feedstock storage tank 1. The mixture is preheated to 250°C in a preheater, and then injected into cracker 3 using a high-efficiency atomizing nozzle. The oil mist comes into millisecond contact with the Beta molecular sieve catalyst, further mixing and heating, resulting in a preliminary thermal cracking reaction at 620°C. The gasoline and diesel conversion rate is 80%, the low-carbon olefin yield is 33.3%, and the dry gas yield is 6.3%. The spent catalyst enters regenerator 9 and undergoes a regeneration reaction with a regenerating agent at 560°C. The regenerated catalyst material is returned to cracker 3 via a return controller at a catalyst-to-oil ratio of 20 to continue circulating and cracking the mixture. The high-temperature mixture after the reaction enters the first fractionation tower 6 for component separation. The top temperature of the fractionation tower is 200°C, the bottom temperature is 250°C, and the top pressure is 0.4... At MPa, the cracked gas is separated to obtain low-carbon olefins such as ethylene, propylene, and butene, which are output as products through the olefin mixture outlet into the olefin storage tank. The intermediate heavy fraction is mixed with recycle oil and slurry oil and passed through intermediate tank 11. After being heated by the preheater, it is used as feedstock in cracker 2 12 and mixed with the regenerated cracking catalyst returned from regenerator 9 (catalyst-to-oil ratio of 18). A cyclic cracking reaction is carried out at 750°C, and the feedstock conversion rate is 80%, the low-carbon olefin yield is 28.3%, the aromatics yield is 65.5%, and the dry gas yield is 6.2%. After the reaction, the mixed oil and gas and the spent catalyst undergo gas-solid separation. The coked spent catalyst is fed into regenerator 9 after flow control and undergoes a regeneration reaction with regenerator oxygen at 450°C. The regenerated catalyst material is returned to cracker 1 3 / cracker 2 12 through the return controller at a catalyst-to-oil ratio of 8 to continue participating in the cycle. The first step involves cracking the mixed oil and gas. The oil and gas, after further cracking, enter the second gas-liquid fractionation tower 13 directly without condensation. The tower has a top temperature of 200°C, a bottom temperature of 250°C, and a top pressure of 0.2 MPa. The product is separated into different fractions. The cracked gas yields low-carbon olefins such as ethylene, propylene, and butene, which are output as products through the low-carbon olefin outlet into the olefin storage tank. The gasoline fraction, after further separation in the fractionation tower, yields low-carbon aromatics such as benzene, toluene, and xylene. The non-aromatic content of these aromatics already meets product specifications, eliminating the need for aromatic extraction. Ultimately, this method achieves a total low-carbon olefin yield of approximately 30.1%, a total low-carbon aromatic yield of approximately 66.9%, and a total dry gas yield of approximately 2.9%. It successfully achieves the co-production of olefins and aromatics under relatively mild conditions, with strong feedstock adaptability, no need for desulfurization pretreatment, and aromatic products such as benzene, toluene, and xylene can be obtained directly through simple fractionation.

[0045] Example 3: This embodiment provides a method for the combined preparation of olefins and aromatics from hydrocarbons, specifically including the following steps: Liquid hydrocarbon feedstock (C6+ mixed oil) with carbon numbers 4-20 is released from feedstock storage tank 1. The mixed oil and gas is preheated to 450°C in a preheater, and then injected into cracker 3 using a high-efficiency atomizing nozzle. The oil mist comes into millisecond contact with the Beta molecular sieve catalyst, further mixing and heating, resulting in a preliminary thermal cracking reaction at 550°C. The resulting C6+ mixed oil has a conversion rate of 82%, a low-carbon olefin yield of 32.5%, and a dry gas yield of 5.6%. The spent catalyst enters regenerator 9 and undergoes a regeneration reaction with a regenerating agent at 700°C. The regenerated catalyst material is returned to cracker 3 via a return controller at a catalyst-to-oil ratio of 10 to continue circulating and cracking the mixed oil and gas. The high-temperature mixed oil and gas after the reaction enters the first fractionation tower 6 for component separation. The top temperature of the fractionation tower is 150°C, the bottom temperature is 200°C, and the top pressure is 0.5... At MPa, the cracked gas is separated to obtain low-carbon olefins such as ethylene, propylene, and butene, which are output as products through the olefin mixture outlet into the olefin storage tank. The intermediate heavy fraction is mixed with recycle oil and slurry oil and passed through intermediate tank 11. After being heated by the preheater, it is used as feedstock in cracker 2 12 and mixed with the regenerated cracking catalyst returned from regenerator 9 (catalyst-to-oil ratio of 15). A cyclic cracking reaction is carried out at 700°C, and the feedstock conversion rate is 85%, the low-carbon olefin yield is 27.2%, the aromatics yield is 68.2%, and the dry gas yield is 4.6%. After the reaction, the mixed oil and gas and the spent catalyst undergo gas-solid separation. The coked spent catalyst is fed into regenerator 9 after flow control and undergoes a regeneration reaction with regenerator oxygen at 550°C. The regenerated catalyst material is returned to cracker 1 3 / cracker 2 12 through the return controller at a catalyst-to-oil ratio of 8 to continue to participate in the cycle and cracking. The mixed oil and gas, after undergoing further cracking, directly enters the second gas-liquid fractionation tower 13 without condensation. The tower has a top temperature of 150°C, a bottom temperature of 280°C, and a top pressure of 0.5 MPa. The product is separated into different fractions. The cracked gas is separated to obtain low-carbon olefins such as ethylene, propylene, and butene, which are output as products into the olefin storage tank via the low-carbon olefin outlet. The gasoline fraction, after being separated in the fractionation tower, yields low-carbon aromatics such as benzene, toluene, and xylene. The non-aromatic content of these aromatics already meets product specifications, eliminating the need for aromatic extraction. Ultimately, this method achieves a total low-carbon olefin yield of approximately 7% and a total low-carbon aromatic yield of approximately 90.5%, with a BTX yield of 72.1% and a dry gas yield of approximately 2.5%. Under the aforementioned process conditions, this method also achieves efficient co-production of olefins and aromatics, demonstrating the technical advantages of wide feedstock adaptability, no need for deep desulfurization, and easy separation of aromatic products.

[0046] Example 4: This embodiment provides a method for the combined preparation of olefins and aromatics from hydrocarbons, specifically including the following steps: Liquid hydrocarbon feedstock (C5+ mixed oil) with carbon numbers 4-20 is released from feedstock storage tank 1. The mixed oil and gas is preheated to 450°C in a preheater, and then injected into cracker 3 using a high-efficiency atomizing nozzle. The oil mist comes into millisecond contact with the ultra-stable Y molecular sieve catalyst, further mixing and heating, resulting in a preliminary thermal cracking reaction at 600°C. The resulting C5+ mixed oil has a conversion rate of 83%, a low-carbon olefin yield of 33.6%, and a dry gas yield of 8.9%. The spent catalyst enters regenerator 9 and undergoes a regeneration reaction with a regenerating agent at 750°C in an oxygen-containing atmosphere. The regenerated catalyst material is returned to cracker 3 via a return controller at a catalyst-to-oil ratio of 15 to continue circulating and cracking the mixed oil and gas. The high-temperature mixed oil and gas after the reaction enters the first fractionation tower 6 for component separation. The top temperature of the fractionation tower is 200°C, the bottom temperature is 300°C, and the top pressure is 1.5. At MPa, the cracked gas is separated to obtain low-carbon olefins such as ethylene, propylene, and butene, which are output as products through the olefin mixture outlet into the olefin storage tank. The intermediate heavy fraction is mixed with recycle oil and slurry oil and passed through intermediate tank 11. After being heated by the preheater, it is used as feedstock in cracker 2 12 and mixed with the regenerated cracking catalyst returned from regenerator 9 (catalyst-to-oil ratio of 25). A cyclic cracking reaction is carried out at 750°C, and the feedstock conversion rate is 88%, the yield of low-carbon olefins is 25.5%, the yield of aromatics is 66.5%, and the dry gas yield is 8%. The mixed oil and gas then undergoes gas-solid separation with the spent catalyst. The coked spent catalyst, after flow control, enters regenerator 9 and reacts with the regenerating agent oxygen at 700°C for a regeneration reaction. The regenerated catalyst material, at a catalyst-to-oil ratio of 15, is returned to cracker 3 / cracker 12 via a return controller to continue circulating and cracking the mixed oil and gas. The oil and gas after further cracking, without condensation, directly enters the second gas-liquid fractionation tower 13, where the top temperature is 200°C, the bottom temperature is 300°C, and the top pressure is 0.25. MPa; the product is separated into different fractions. The cracked gas is separated to obtain low-carbon olefins such as ethylene, propylene and butene, which are output as products into the olefin storage tank through the low-carbon olefin outlet. The gasoline fraction is separated into low-carbon aromatics such as benzene, toluene and xylene after fractionation in a distillation tower. The non-aromatic content of these aromatics already meets the product specifications, so there is no need for aromatic extraction. Finally, the method in this embodiment achieves a total yield of about 24.8% for low-carbon olefins, a total yield of about 69.4% for low-carbon aromatics, and a total dry gas yield of about 5.8%. Under the process conditions described above, this method also achieves efficient co-production of olefins and aromatics, demonstrating the technical characteristics of wide feedstock adaptability, no need for deep desulfurization and easy separation of aromatic products.

[0047] Comparative Example 1: This comparative example is basically the same as Example 1, except that: The feedstock consists of liquid hydrocarbons (a mixture of gasoline and diesel) with a carbon number between 4 and 20, requiring no desulfurization refining. The feedstock is preheated to 400°C and then reacted in a single reactor with a regenerated catalyst at 650°C (catalyst-to-oil ratio 20). The reaction mixture is then separated in a stripper, the catalyst is regenerated in a regenerator, and the oil and gas mixture is separated in a fractionation tower to obtain the final products. The fractionation tower has a top temperature of 200°C, a bottom temperature of 300°C, and a top pressure of 0.5 MPa. The heavy fractions (diesel, slurry oil, etc.) are directly output as byproducts without further recycling or cracking. The final yield is 9% for low-carbon olefins, 45% for low-carbon aromatics, and 0.95% for hydrogen.

[0048] Comparative Example 2: This comparative example uses a traditional thermal cracking method. The specific steps are as follows: A gasoline-diesel mixture with the same composition as in Example 1 is released from the same feedstock storage tank and mixed with dilution steam at a ratio of 1:0.4 (mass ratio). After preheating to 550°C, it is fed into a tubular furnace reactor (radiation section) for pure thermal cracking at 820°C, with a residence time of approximately 0.3 seconds. The high-temperature stream after the reaction is rapidly introduced into a quench boiler to terminate the reaction, and then enters an oil washing tower, a water washing tower, and a separation system. The products are separated into hydrogen, methane, ethylene, propylene, mixed C4, cracked gasoline, cracked diesel, and fuel oil through a series of fractionation towers. The cracked gasoline fraction can be sent to an aromatics extraction unit to recover benzene, toluene, and xylene (BTX), but the heavy cracked diesel and fuel oil are output as low-value fuel oil byproducts and are not recycled for cracking. The final yield of low-carbon olefins is 16%, low-carbon aromatics is 36%, and hydrogen is 0.2%.

[0049] As can be seen from the above embodiments: 1. Strong adaptability to raw materials and low pretreatment requirements: This application is applicable to liquid hydrocarbon raw materials with carbon numbers of 4-20, such as naphtha, catalytic gasoline, and light diesel oil, which have huge differences in the content of impurities such as sulfur and nitrogen and hydrocarbon composition. Unlike steam cracking or catalytic reforming, the raw materials do not need to undergo harsh purification such as deep desulfurization. A variety of inexpensive or by-product raw materials can be used directly, realizing the high-value and flexible utilization of raw materials.

[0050] 2. Simultaneous Production of Olefins and Aromatics: Traditional refining processes typically focus on producing only a single product type. For example, catalytic cracking mainly produces gasoline and liquefied petroleum gas (LPG), catalytic reforming mainly produces high-octane gasoline and aromatics, while steam cracking mainly produces ethylene and propylene. This application, through the coupling of two-stage cracking reactions and fractionation, simultaneously achieves the cracking of large molecular hydrocarbons (producing low-carbon olefins such as ethylene and propylene) and the aromatization of intermediate products (producing low-carbon aromatics such as benzene, toluene, and xylene, as well as byproduct hydrogen) in the same process, thus optimizing the product structure.

[0051] 3. Low investment: fluidized bed or cracking reactor units are far cheaper than reforming units. Compared to reforming units or steam cracking units that require the construction of multiple fixed-bed reactors, complex high-pressure loops, and expensive platinum-based catalysts, the fluidized bed or cracking reaction process utilized in this application is technically mature and has a large existing stock in refineries. The equipment investment, catalyst cost, and engineering design fees for technical transformation or new construction are far lower than those for a brand-new aromatics complex or ethylene unit of the same scale, which can significantly reduce costs.

[0052] 4. Aromatic separation eliminates the need for aromatic extraction, resulting in low energy consumption: In traditional aromatic production, separating benzene, toluene, xylene, etc., from reformed oil requires the core unit of "aromatic extraction." This process relies on large extraction and stripping towers and necessitates the recycling of large quantities of solvent, leading to extremely high energy consumption for heating, cooling, and solvent regeneration. The fluidized bed or cracking reactor process of this application, through optimized reaction conditions and catalysts, allows the aromatic products to be directly obtained through fractionation without additional extraction, thus bypassing the energy-intensive solvent extraction step and significantly reducing the energy consumption and operating costs of the separation unit from the root cause.

[0053] 5. Aromatics production does not require deep desulfurization of feedstock: Traditional catalytic reforming processes have extremely high requirements for feedstock sulfur content, typically needing to be reduced to below 0.5 ppm. This necessitates complex pretreatment processes and additional desulfurization equipment, increasing investment and operating costs. In contrast, the fluidized bed or riser process of this application has low requirements for feedstock sulfur content and requires no special treatment for the sulfur content of industrial feedstock oil. The molecular sieve catalyst used in this application has stronger tolerance to sulfides, and the sulfides generated during the reaction can be treated by coking in a regenerator, eliminating the need for deep desulfurization as required by reforming processes. This feature significantly reduces investment and energy consumption in the feedstock pretreatment stage of the fluidized bed or riser process, especially when processing high-sulfur crude oil.

[0054] 6. High Yields of Olefins and Aromatics: In the cracking reaction process, the specialized catalyst in this application promotes the generation and rearrangement of carbocations, enabling the efficient cracking of heavy oil molecules into target low-carbon olefins. Simultaneously, this catalytic effect guides some intermediate olefins to undergo further aromatization. Based on this mechanism, by precisely and synergistically optimizing process conditions such as reaction temperature, catalyst-to-oil ratio, and residence time, highly efficient synergy between the cracking (increased olefin production) and aromatization (increased aromatics production) pathways is achieved, effectively suppressing side reactions that generate dry gas and coke. Ultimately, this application's technology can directionally convert more raw material carbon atoms into high-value olefin and aromatic products.

[0055] 7. The fluidized bed process addresses the issue of uneven gas-solid contact in traditional catalytic cracking processes: This application employs a fluidized bed or cracking reactor process, achieving efficient and uniform gas-solid contact through "catalyst fluidization within the cracking reactor." Preheated diesel / gasoline feedstock and high-temperature catalyst flow in parallel upwards within the riser, fully dispersing catalyst particles. The feedstock molecules can achieve a contact area with the catalyst active sites that is 10-20 times larger than in a fixed bed. Furthermore, from a reaction mechanism perspective, this uniform contact can directionally guide hydrocarbon molecules in diesel / gasoline to undergo "selective cracking" (chain scission of long-chain alkanes to form C2-C4 olefins) and "controlled aromatization" (dehydrogenation of cycloalkanes to form monocyclic aromatics), thus avoiding excessive cracking.

[0056] 8. The catalyst regeneration system solves the problem of "difficulty in recycling catalysts after deactivation" in existing processes, which can reduce costs and ensure continuous production.

[0057] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for the combined preparation of olefins and aromatics from hydrocarbons, characterized in that, include: The atomized feed oil undergoes a preliminary cracking reaction under the action of a catalyst to obtain preliminary cracked gas and catalyst to be generated; The preliminary cracked gas is subjected to a first fractionation to obtain low-carbon olefins and heavy fractions; The atomized heavy fraction is subjected to a cyclic pyrolysis reaction under the action of a catalyst to obtain cyclic pyrolysis gas and catalyst to be generated. The recycled cracked gas is subjected to a second fractionation to obtain low-carbon olefins and low-carbon aromatics. The initial pyrolysis reaction and the cyclic pyrolysis reaction are both carried out in a circulating fluidized bed or a riser.

2. The method for jointly preparing olefins and aromatics from hydrocarbons according to claim 1, characterized in that, The feedstock oil is selected from at least one of naphtha, gasoline, and light diesel oil, and the feedstock oil is a hydrocarbon with a carbon number in the range of 4-20.

3. The method for jointly preparing olefins and aromatics from hydrocarbons according to claim 1, characterized in that, The catalyst is selected from at least one of ZSM-5 molecular sieve, rare earth-Y molecular sieve, ultrastable Y molecular sieve, X-type molecular sieve, basic solid porous catalyst and β molecular sieve catalyst.

4. The method for jointly preparing olefins and aromatics from hydrocarbons according to claim 1, characterized in that, The temperature of the preliminary pyrolysis reaction is 450℃-650℃, and the agent-to-oil ratio of the preliminary pyrolysis reaction is 1-50:

1.

5. The method for jointly preparing olefins and aromatics from hydrocarbons according to claim 1, characterized in that, The temperature of the catalyst in the preliminary pyrolysis reaction is 650℃-1000℃; And / or, the temperature of the raw material oil before atomization is 100-500℃; And / or, in the first fractionation step, the temperature at the top of the fractionation column is 50-200℃, the temperature at the bottom of the column is 100-300℃, and the pressure at the top of the column is 0-2 MPa.

6. The method for jointly preparing olefins and aromatics from hydrocarbons according to claim 1, characterized in that, The temperature of the cyclic pyrolysis reaction is 500℃-800℃, and the agent-to-oil ratio of the cyclic pyrolysis reaction is 1-50:

1.

7. The method for jointly preparing olefins and aromatics from hydrocarbons according to claim 1, characterized in that, The temperature of the catalyst in the cyclic pyrolysis reaction is 600℃-850℃; And / or, the temperature of the heavy fraction before atomization is 100-500℃; And / or, in the second fractionation step, the temperature at the top of the fractionation column is 50-200℃, the temperature at the bottom of the column is 100-300℃, and the pressure at the top of the column is 0-2 MPa.

8. The method for jointly preparing olefins and aromatics from hydrocarbons according to claim 1, characterized in that, It also includes catalyst regeneration, wherein the catalyst regeneration temperature is 580℃-1000℃ and the atmosphere is an oxidizing atmosphere containing oxygen.

9. An apparatus used in the method for the combined preparation of olefins and aromatics from hydrocarbons as described in any one of claims 1-8, characterized in that, Including pyrolyzer one and pyrolyzer two; The reactant inlet of the first pyrolysis unit is connected to a feedstock oil storage tank. The primary pyrolysis gas outlet of the first pyrolysis unit is sequentially connected to a first gas-liquid fractionation tower, a regenerator, and a dry gas storage tank. The C5+ component outlet of the first gas-liquid fractionation tower is connected to an intermediate tank. The total fraction outlet of the intermediate tank is connected to the reactant inlet of the second pyrolysis unit. The circulating pyrolysis gas outlet of the second pyrolyzer is sequentially connected to a regenerator and a second gas-liquid fractionation tower.

10. The apparatus for the combined preparation of olefins and aromatics from hydrocarbons according to claim 9, characterized in that, It also includes a catalyst regenerator, wherein the catalyst inlet of the catalyst regenerator is connected to the solid phase outlet of the first pyrolyzer and the second pyrolyzer, respectively.

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