A catalytic conversion method and system for producing light olefins and light aromatics from hydrotreated diesel

Abstract

The present invention provides a catalytic conversion method for producing light olefins and light aromatics from hydrotreated diesel, which comprises: S1, contacting the hydrotreated diesel with a first catalyst in a first riser reaction zone to carry out a first catalytic conversion reaction to obtain a first oil-catalyst mixture; S2, introducing the first oil-catalyst mixture into a second riser reaction zone to contact with a second catalyst to carry out a second catalytic conversion reaction to obtain a second oil-catalyst mixture; S3, carrying out gas-solid separation and stripping on the second oil-catalyst mixture in a settler to obtain an oil-gas product and a mixed spent catalyst; S4, introducing the mixed spent catalyst into a catalyst separation device for separation to obtain a first spent catalyst and a second spent catalyst. The present invention also provides a catalytic conversion system. The present invention can create a suitable reaction environment for the ring-opening reaction and side-chain cleavage reaction of monocyclic aromatics with cycloalkyl side chains in hydrotreated diesel, thereby improving the yields of light olefins and light aromatics.

Description

Technical Field

[0001] The present invention relates to the field of petrochemical industry, and particularly relates to a catalytic conversion method and system for producing light olefins. Background Art

[0002] Hydrotreating diesel can convert bicyclic aromatic hydrocarbons into monocyclic aromatic hydrocarbons. The hydrotreated diesel can be used as a raw material for producing light olefins and light aromatics, and light olefins and light aromatics are obtained after catalytic conversion.

[0003] For example, CN113736511A discloses a method for hydrocarbon oil conversion, including: (1) introducing a hydrocatalytic diesel raw material 1 into a riser reactor 3 in a first reaction zone under the action of lifting steam 2, contacting with a catalyst and then ascending to carry out a catalytic cracking reaction to obtain a stream I; (2) introducing an alkyl transfer agent 5 (benzene and / or toluene) and the stream I into a fluidized bed reactor in a second reaction zone 4 to carry out an alkyl transfer reaction to obtain a stream II; (3) introducing the stream II into a settler 6 for separation to obtain reaction oil gas 8 and spent catalyst; introducing at least part of the spent catalyst into a regenerator 11 through a stripper 7 and a spent catalyst riser 9 in sequence for regeneration, and recycling the obtained regenerated catalyst back to the first reaction zone to participate in the catalytic cracking reaction; recycling the remaining part of the spent catalyst back to the second reaction zone 4 through a circulating inclined pipe 10 to participate in the alkyl transfer reaction; the amount of the spent catalyst recycled back to the second reaction zone 4 accounts for 5-20% by weight of the total amount of the spent catalyst obtained in step (3); separating the reaction oil gas 8 obtained in step (3) to obtain a gasoline fraction and a diesel fraction, the initial boiling point of the gasoline fraction is 60-95°C, and the final boiling point is 180-205°C. Optionally, introducing the gasoline fraction into the second reaction zone to participate in the alkyl transfer reaction together with the alkyl transfer agent. A main air of the regenerator 12 is arranged at the bottom of the regenerator 11, and the main air of the regenerator 12 is used to convey main air into the regenerator 11; a cyclone separator 13 is arranged on the inner side surface of the regenerator 11, and the cyclone separator 13 is used for re-settling and separating the spent catalyst in the regenerator 11 to obtain regenerated flue gas 14 and the regenerated catalyst; an external heat exchanger 15 is arranged on the side surface of the regenerator 11.

[0004] However, it is still necessary to further improve the yields of light olefins and light aromatics produced from hydrotreated diesel. Summary of the Invention

[0005] The object of the present invention is to further improve the yields of light olefins and light aromatics produced from hydrotreated diesel.

[0006] To achieve the above object, the present invention provides a catalytic conversion method for producing light olefins and light aromatics from hydrotreated diesel, and the catalytic conversion method comprises the following steps: S1, contacting the hydrotreated diesel with a first catalyst in a first riser reaction zone to carry out a first catalytic conversion reaction to obtain a first oil-catalyst mixture; S2, introducing the first oil-catalyst mixture into a second riser reaction zone to contact with a second catalyst to carry out a second catalytic conversion reaction to obtain a second oil-catalyst mixture; S3, carrying out gas-solid separation and stripping on the second oil-catalyst mixture in a settler to obtain an oil-gas product and a mixed spent catalyst; S4, introducing the mixed spent catalyst into a catalyst separation device for separation to obtain a first spent catalyst and a second spent catalyst, and the catalyst separation device comprises a primary catalyst separator and a secondary catalyst separator; S5, introducing the first spent catalyst into a first regeneration zone for first regeneration and then returning to step S1 to participate in the first catalytic conversion reaction as the first catalyst, and introducing the second spent catalyst into a second regeneration zone for second regeneration and then returning to step S2 to participate in the second catalytic conversion reaction as the second catalyst, and the second regeneration zone is located in the first regeneration zone.

[0007] The present invention also provides a catalytic conversion system for producing light olefins and light aromatics from hydrotreated diesel, and the catalytic conversion system comprises a first riser reaction zone, a second riser reaction zone, a settler, a catalyst separation device and a regenerator; the upper end of the first riser reaction zone is communicated with the lower end of the second riser reaction zone; the upper end of the second riser reaction zone is communicated with the lower end of the settler; a gas-solid separation device is further arranged in the settler; the lower end of the settler is further connected with a stripper; the lower part of the stripper has a mixed spent catalyst outlet; the catalyst separation device comprises a primary catalyst separator and a secondary catalyst separator, the primary catalyst separator has a material inlet communicated with the mixed spent catalyst outlet, a first spent catalyst outlet and a gas-solid mixture outlet, and the secondary catalyst separator has a logistics inlet communicated with the gas-solid mixture outlet of the primary catalyst separator, a second spent catalyst outlet and an oil-gas conveying outlet; the regenerator comprises a first regenerator and a second regenerator, the second regenerator is arranged in the cavity of the first regenerator, a first regeneration zone is arranged in the first regenerator, and a second regeneration zone is arranged in the second regenerator; a first spent catalyst conveying connection is provided between the first spent catalyst outlet and the first regeneration zone; a second spent catalyst conveying connection is provided between the second spent catalyst outlet and the second regeneration zone; a first regenerated catalyst conveying connection is provided between the first regeneration zone and the first riser reaction zone; a second regenerated catalyst conveying connection is provided between the second regeneration zone and the second riser reaction zone.

[0008] Through the above technical solution, the present invention first reacts the hydrotreated diesel with a first catalyst rich in Y zeolite catalyst, causing the aromatics with cycloalkyl side chains to undergo ring-opening reactions to generate aromatics with alkyl side chains, and then continues to react with a second catalyst rich in shape-selective zeolite catalyst, causing the side chains of alkyl aromatics to break and at the same time suppressing the occurrence of hydrogen transfer reactions, thereby increasing the yields of light olefins and light aromatics.

[0009] Other features and advantages of the present invention will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific implementation, they are used to explain the present invention, but do not constitute a limitation to the present invention. In the drawings:

[0011] Figure 1 It is a schematic structural diagram of a catalytic conversion system according to an embodiment of the present invention.

[0012] DESCRIPTION OF THE REFERENCE NUMERALS

[0013] Figure 1 In the figure, the reference numerals are described as follows:

[0014] 1 - First riser reactor zone 2 - Second riser reactor zone 3 - Settler

[0015] 4 - Stripper 5 - First regeneration zone 6 - Second regeneration zone

[0016] 11 - Hydrotreated diesel 12 - Pre-lift gas 13 - Stripping gas

[0017] 14 - Stripping baffle 15 - Cyclone separator 16 - Gas collecting chamber

[0018] 17 - Reaction oil and gas 18 - Mixed spent catalyst transfer pipe 19 - Primary catalyst separator

[0019] 20 - First spent catalyst transfer pipe 21 - Gas-solid mixture transfer pipe 22 - Secondary catalyst separator

[0020] 23 - Second spent catalyst transfer pipe 24 - Residual oil and gas 25, 26 - Main air

[0021] 27 - First regenerated catalyst transfer pipe 28 - Second regenerated catalyst transfer pipe 29, 30 - Cyclone separator

[0022] 31 - Gas collecting chamber 32 - Regenerated flue gas SPECIFIC IMPLEMENTATION

[0023] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only for the purpose of illustrating and explaining the present invention, and are not intended to limit the present invention.

[0024] Referring to Figure 1 , the present invention provides a catalytic conversion method for producing light olefins and light aromatics from hydrotreated diesel, and the catalytic conversion method includes the following steps: S1. Contacting the hydrotreated diesel with a first catalyst in a first riser reaction zone to carry out a first catalytic conversion reaction to obtain a first oil-catalyst mixture; S2. Introducing the first oil-catalyst mixture into a second riser reaction zone to contact with a second catalyst to carry out a second catalytic conversion reaction to obtain a second oil-catalyst mixture; S3. Carrying out gas-solid separation and stripping on the second oil-catalyst mixture in a settler to obtain an oil-gas product and a mixed spent catalyst; S4. Introducing the mixed spent catalyst into a catalyst separation device for separation to obtain a first spent catalyst and a second spent catalyst, and the catalyst separation device includes a primary catalyst separator and a secondary catalyst separator; S5. Introducing the first spent catalyst into a first regeneration zone for first regeneration and then returning to step S1 as the first catalyst to participate in the first catalytic conversion reaction, and introducing the second spent catalyst into a second regeneration zone for second regeneration and then returning to step S2 as the second catalyst to participate in the second catalytic conversion reaction, and the second regeneration zone is located in the first regeneration zone.

[0025] In the present invention, the materials (including the first catalyst, reaction oil-gas, and fluidization medium) that have undergone the first catalytic conversion in the first riser reaction zone enter the second riser reaction zone without separation to contact with the second catalyst for the second catalytic conversion reaction, that is, the relay of the first catalytic conversion reaction and the second catalytic conversion reaction can be realized.

[0026] Optionally, in order to facilitate the separation of the first spent catalyst and the second spent catalyst, the particle size and density of the first catalyst are both greater than those of the second catalyst.

[0027] Optionally, the first catalyst contains 80-100% by mass of heavy oil catalyst and 0-20% by mass of light oil catalyst; the second catalyst contains 0-20% by mass of heavy oil catalyst and 80-100% by mass of light oil catalyst.

[0028] Preferably, the first catalyst contains 90-100% by mass of heavy oil catalyst and 0-10% by mass of light oil catalyst; the second catalyst contains 0-10% by mass of heavy oil catalyst and 90-100% by mass of light oil catalyst.

[0029] Among them, optionally, the heavy oil catalyst comprises unmodified Y zeolite or modified Y zeolite, clay and binder. Among them, based on the total weight of the heavy oil catalyst, the content of unmodified Y zeolite or modified Y zeolite is 10-80%, preferably 30-60%, the content of clay is 10-80%, preferably 15-60%, and the content of binder is 10-30%, preferably 10-20%. The particle size range of the heavy oil catalyst is 60-250 μm, preferably 80-200 μm, and the particle density is 1150-1600 kg / m 3 , preferably 1300-1500 kg / m 3 . The unmodified Y zeolite or modified Y zeolite can be selected from one or more of HY, USY, REUSY, REY, REHY, DASY, REDASY, or Y zeolite obtained by treatment with various metal oxides. The clay is selected from various clays that can be used as catalyst components, such as kaolin, montmorillonite, bentonite, etc. The binder is selected from one or two or three mixtures of silica sol, aluminum sol and pseudo-boehmite, and the preferred binder among them is the double-aluminum binder of aluminum sol and pseudo-boehmite.

[0030] Among them, optionally, the light oil catalyst comprises unmodified ZSM-5 zeolite or modified ZSM-5 zeolite, clay and binder.

[0031] Among them, optionally, based on the total weight of the catalyst, the content of unmodified ZSM-5 zeolite or modified ZSM-5 zeolite is 10-60%, preferably 20-50%, the content of clay is 10-80%, preferably 20-70%, and the content of binder is 10-30%, preferably 10-20%. The modified ZSM-5 zeolite is, for example, selected from one or more of ZRP zeolite, phosphorus-containing ZRP zeolite, rare-earth-containing ZRP zeolite, phosphorus- and rare-earth-containing ZRP zeolite, phosphorus- and alkaline-earth-metal-containing ZRP zeolite, and phosphorus- and transition-metal-containing ZRP zeolite, and preferably phosphorus- and rare-earth-containing ZRP zeolite. The clay is selected from various clays that can be used as catalyst components, such as kaolin, montmorillonite, bentonite, etc. The binder is selected from one or two or three mixtures of silica sol, aluminum sol and pseudo-boehmite, and the preferred binder among them is the double-aluminum binder of aluminum sol and pseudo-boehmite.

[0032] Among them, optionally, the particle size range of the light oil catalyst is 10-100 μm, preferably 30-80 μm, and the particle density is 800-1200 kg / m 3 , preferably 900-1050 kg / m 3 .

[0033] Optionally, the first regeneration zone is arranged in a first regenerator, the second regeneration zone is arranged in the cavity of the first regenerator, the second regenerator is arranged in the first regeneration zone, and both the first regeneration zone and the second regeneration zone adopt complete regeneration.

[0034] Optionally, the regeneration temperature of the first regeneration zone is 660 - 720 °C, preferably 680 - 700 °C, the catalyst distribution density is 50 - 400 kg / m 3 , preferably 100 - 300 kg / m 3 , and the main air residence time is 0.5 - 20 s, preferably 2 - 10 s.

[0035] Optionally, the regeneration temperature of the second regeneration zone is 670 - 730 °C, preferably 690 - 710 °C, the catalyst distribution density is 30 - 350 kg / m 3 , preferably 80 - 250 kg / m 3 , and the main air residence time is 0.5 - 15 s, preferably 2 - 10 s.

[0036] Optionally, the reaction temperature of the first riser reactor zone is 500 - 620 °C, preferably 520 - 600 °C; the catalyst - to - oil ratio is 1 - 15, preferably 2 - 10; the reaction time is 1 - 10 seconds, preferably 2 - 8 seconds. The hydrotreated diesel 11 can be pre - heated to 180 - 300 °C and then sprayed into the first riser reactor zone through a nozzle.

[0037] Optionally, the reaction temperature of the second riser reactor zone is 520 - 640 °C, preferably 540 - 620 °C, the catalyst - to - oil ratio is 2 - 20, preferably 4 - 15; the reaction time is 1 - 15 seconds, preferably 2 - 10 seconds.

[0038] Optionally, the hydrotreated diesel is a product obtained by hydro - treating a mixture of one or more selected from straight - run diesel, catalytic cracking diesel, coking diesel, and hydrocracking diesel, and the content of bicyclic aromatic hydrocarbons in the hydrotreated diesel is not more than 20% by weight, preferably not more than 10% by weight.

[0039] Optionally, the catalytic conversion method further includes separating a diesel fraction from the oil - gas product in step S3, hydrogenating it, and then returning it to step S1.

[0040] Optionally, the method further includes introducing a pre - lift gas at the bottom of the first riser reactor zone, and the pre - lift gas can be selected from one or more of steam, nitrogen, and dry gas, preferably steam.

[0041] The present invention also provides a catalytic conversion system for producing light olefins and light aromatics from hydrogenated diesel. The catalytic conversion system includes a first riser reaction zone, a second riser reaction zone, a settler, a catalyst separation device, and a regenerator; the upper end of the first riser reaction zone is connected to the lower end of the second riser reaction zone; the upper end of the second riser reaction zone is connected to the lower end of the settler; a gas-solid separation device is also provided in the settler; a stripper is further connected to the lower end of the settler; the lower part of the stripper has a mixed spent catalyst outlet; the catalyst separation device includes a primary catalyst separator and a secondary catalyst separator. The primary catalyst separator has a material inlet connected to the mixed spent catalyst outlet, a first spent catalyst outlet, and a gas-solid mixture outlet. The secondary catalyst separator has a logistics inlet connected to the gas-solid mixture outlet of the primary catalyst separator, a second spent catalyst outlet, and an oil-gas transport outlet; the regenerator includes a first regenerator and a second regenerator. The second regenerator is disposed within the cavity of the first regenerator. A first regeneration zone is provided in the first regenerator, and a second regeneration zone is provided in the second regenerator; there is a first spent catalyst transport connection between the first spent catalyst outlet and the first regeneration zone; there is a second spent catalyst transport connection between the second spent catalyst outlet and the second regeneration zone; there is a first regenerated catalyst transport connection between the first regeneration zone and the first riser reaction zone; there is a second regenerated catalyst transport connection between the second regeneration zone and the second riser reaction zone.

[0042] Optionally, the catalyst separation device separates the first catalyst from the second catalyst based on the difference in particle size and density between the first catalyst and the second catalyst.

[0043] Optionally, as an implementation manner of having a first regenerated catalyst transport connection between the first regeneration zone and the first riser reaction zone, a first catalyst inlet is further provided at the lower part of the first riser reaction zone. The first catalyst inlet can be used to introduce fresh first catalyst or regenerated first catalyst. As an implementation manner of having a second regenerated catalyst transport connection between the second regeneration zone and the second riser reaction zone, a second catalyst inlet is further provided at the lower part of the second riser reaction zone. The second catalyst inlet can be used to introduce fresh second catalyst or regenerated second catalyst.

[0044] Optionally, the catalyst separator is one or a combination of a cyclone type quick separator, a three-blade type quick separator, an ejection type quick separator, a U-shaped tube type separator, an attached wall cutting type quick separator, etc., preferably a cyclone type quick separator; the number of catalyst separators connected to the outside of each settler is one or more; there is a series and / or parallel relationship between the multiple catalyst separators.

[0045] In one embodiment, referring to Figure 1 , a primary catalyst separator is connected to the outside of the stripper. The lower part of the primary catalyst separator has the first spent catalyst outlet, and the upper part of the primary catalyst separator has a gas-solid mixture outlet; the mixed material outlet is communicated with the material inlet of the secondary catalyst separator; the upper part of the secondary catalyst separator is provided with a residual reaction oil and gas outlet, and the lower part of the secondary catalyst separator is provided with a second spent catalyst outlet.

[0046] According to a particularly preferred embodiment of the present invention, in the present invention, the hydrotreated diesel 11 is preheated to 180 - 300 °C and then injected into the bottom of the first riser reactor zone 1 through a nozzle, and contacts and reacts with the first catalyst introduced into the bottom of the first riser reactor zone 1 through the first regenerated catalyst transfer pipe 27 under the conditions of a reaction temperature of 500 - 620 °C, preferably 520 - 600 °C; a catalyst-to-oil ratio of 1 - 15, preferably 2 - 10; and a reaction time of 1 - 10 seconds, preferably 2 - 8 seconds. The first oil-catalyst mixture after the reaction is introduced into the second riser reactor zone 2 and contacts and reacts with the second catalyst introduced into the second riser reactor zone 2 through the second regenerated catalyst transfer pipe 28 under the conditions of a reaction temperature of 520 - 640 °C, preferably 540 - 620 °C; a catalyst-to-oil ratio of 2 - 20, preferably 4 - 15; and a reaction time of 1 - 15 seconds, preferably 2 - 10 seconds. The second oil-catalyst mixture after the reaction is introduced into the cyclone separator 15 in the settler 3 for separation, and the resulting reaction oil gas 17 is collected through the gas collection chamber 16 and then introduced into the subsequent product separation system. The resulting spent catalyst is introduced into the stripper 4 for stripping, and the stripped spent catalyst is introduced into the first-stage catalyst separator 19 through the mixed spent catalyst transfer pipe 18. The separated first spent catalyst is introduced into the first regeneration zone 5 through the first spent catalyst transfer pipe 20 and contacts the main air 25 introduced into the first regeneration zone 5 for a complete regeneration reaction. The resulting regeneration flue gas 32 is separated from the carried catalyst through the cyclone separator 29 and then collected through the gas collection chamber 31 and introduced into the regeneration flue gas treatment system. The resulting first regenerated catalyst is introduced into the bottom of the first reaction zone 1 through the first regenerated catalyst transfer pipe 27 for recycling. The oil-catalyst mixture separated by the first-stage catalyst separator 19 is introduced into the second-stage catalyst separator 22 through the oil-catalyst mixture transfer pipe 21. The separated second spent catalyst is introduced into the second regeneration zone 6 through the second spent catalyst transfer pipe 23 and contacts the main air 26 introduced into the second regeneration zone 6 for a complete regeneration reaction. The resulting regeneration flue gas 32 is separated from the carried catalyst through the cyclone separator 30 and then collected through the gas collection chamber 31 and introduced into the regeneration flue gas treatment system. The resulting second regenerated catalyst is introduced into the bottom of the second reaction zone 2 through the second regenerated catalyst transfer pipe 28 for recycling. The second regeneration zone 6 is located in the first regeneration zone 5 to facilitate heat transfer between the second regeneration zone 6 and the first regeneration zone 5, so that the temperatures of both regeneration zones are at a relatively high level. The residual oil gas separated by the second-stage catalyst separator 22 is introduced into the settler 3 through the oil gas transfer pipe 24 and mixed with the reaction oil gas 17 and then introduced into the subsequent product separation system together. In the product separation system, the catalytic cracking products are separated into products such as dry gas, cracked gas, gasoline, light oil, and slurry. The resulting diesel is subjected to hydrotreatment and returned to step S1 for reaction again.

[0047] Three catalysts were used in the examples and comparative examples, namely GOR-II catalyst, RAG-6 catalyst and SLA catalyst, all of which were commercial catalysts produced by Qilu Branch of Sinopec Catalyst Company. The specific properties of the three catalysts are shown in Table 1. Among them, GOR-II is a catalyst containing 40 wt% Y zeolite, RAG-6 is a catalyst containing 35 wt% ZSM-5 zeolite, and DMMC-2 is a catalyst containing 15 wt% Y zeolite and 15 wt% ZSM-5 zeolite. Before the experiment, the catalyst was aged for 17 hours under the conditions of 800 °C and 100% steam. The feedstock oil used in the examples and comparative examples was hydrotreated diesel, and its specific properties are shown in Table 2.

[0048] Table 1 Composition and properties of catalysts

[0049] Catalyst GOR-II RAG-6 DMMC-2 Chemical components, %(w) <![CDATA[Al2O3]]> 57.5 51.2 48.1 BET total analysis <![CDATA[BET total surface area / (m 2 ·g -1 )]]> 181.000 197.000 102.491 <![CDATA[Total pore volume / (cm 3 ·g -1 )]]> 0.2240 0.1500 0.1057 <![CDATA[Particle density / (kg / m 3 )]]> 1352 965 987 Particle size distribution, %(w) 0 - 20μm 0.1 0.5 0.1 0 - 40μm 5.1 32.6 17 0 - 80μm 20.3 87.3 70.9 0 - 105μm 50.6 98.5 87.8 > 105μm 49.4 1.5 12.2

[0050] Table 2 Composition and properties of hydrotreated diesel

[0051]

[0052]

[0053] Examples 1-2

[0054] The experiment was carried out on the Figure 1 shown device. The device includes two riser reactors connected in series. The inner diameters of the two riser reactors are both 16 mm and the lengths are both 3000 mm. The preheated hydrotreated diesel and the first catalyst rich in GOR-II catalyst were both introduced into the bottom of the first riser reactor. The two contacted and reacted in the first riser reactor. The oil-agent mixture after the reaction was introduced into the second riser reactor, contacted with the second catalyst rich in RAG-6 catalyst therein and continued to react. The oil-agent mixture after the reaction was separated by a cyclone separator. The catalyst entered the stripper for stripping and then was introduced into a two-stage catalyst separator, divided into a first spent catalyst rich in GOR-II catalyst and a second spent catalyst rich in RAG-6 catalyst. The two spent catalysts were respectively introduced into the first regeneration zone and the second regeneration zone. The regenerated catalyst was returned to the first riser reactor and the second riser reactor for recycling, and the oil and gas were introduced into the fractionation system for separation. The reaction conditions and results are shown in Table 3.

[0055] Example 2

[0056] According to the method of Example 1, the difference is that the first catalyst introduced into the bottom of the first riser reactor is the first catalyst rich in DMMC-2 catalyst. The reaction conditions and results are shown in Table 3.

[0057] Comparative Example 1

[0058] The experiment was carried out on an experimental device. The device includes a riser reactor. The inner diameter of the riser reactor is 16 mm and the length is 5000 mm. The preheated hydrotreated diesel and the DMMC-2 catalyst were both introduced into the bottom of the riser reactor, and the two contacted and reacted in the riser reactor. The oil-catalyst mixture after the reaction was separated by a cyclone separator. The catalyst entered the stripper and then entered the regenerator for regeneration. The regenerated catalyst returned to the riser reactor for recycling, and the oil-gas was introduced into the fractionation system for separation. The reaction conditions and results are shown in Table 3.

[0059] Comparative Example 2

[0060] According to the method in Comparative Example 1, the difference is that the catalyst used in the first riser reactor and the second riser reactor is a mixed catalyst of DMMC-2 catalyst and RAG-6 catalyst with a mass ratio of 1:1. The reaction conditions and results are shown in Table 3.

[0061] Table 3 Reaction conditions and results of Examples 1-2 and Comparative Examples 1-2

[0062]

[0063] It can be seen from Table 3 that the method and system provided by the present invention can improve the yields of light olefins and light aromatics in the production of hydrotreated diesel.

[0064] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0065] In addition, it should be noted that, in the case of no contradiction, the various specific technical features described in the above specific embodiments can be combined in any suitable manner. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0066] In addition, any combination can be made between different embodiments of the present invention, as long as it does not violate the idea of the present invention, and it should also be regarded as the content disclosed by the present invention.

Claims

1. A catalytic conversion method for producing light olefins and light aromatics from hydrotreated diesel, characterized in that, The catalytic conversion method comprises the following steps: S1. Contacting hydrogenated diesel oil with a first catalyst in a first riser reactor reaction zone to carry out a first catalytic conversion reaction to obtain a first oil-catalyst mixture; S2. Introducing the first oil-catalyst mixture into a second riser reactor reaction zone to contact with a second catalyst to carry out a second catalytic conversion reaction to obtain a second oil-catalyst mixture; S3. Carrying out gas-solid separation and stripping on the second oil-catalyst mixture in a settler to obtain an oil-gas product and a mixed spent catalyst; S4. Introducing the mixed spent catalyst into a catalyst separation device for separation to obtain a first spent catalyst and a second spent catalyst, wherein the catalyst separation device comprises a primary catalyst separator and a secondary catalyst separator; S5. Introducing the first spent catalyst into a first regeneration zone for first regeneration and then returning to step S1 to participate in the first catalytic conversion reaction as the first catalyst, and introducing the second spent catalyst into a second regeneration zone for second regeneration and then returning to step S2 to participate in the second catalytic conversion reaction as the second catalyst, wherein the second regeneration zone is located in the first regeneration zone; Wherein, the first catalyst contains 80-100% by mass of a heavy oil catalyst and 0-20% by mass of a light oil catalyst; the second catalyst contains 0-20% by mass of a heavy oil catalyst and 80-100% by mass of a light oil catalyst; the heavy oil catalyst comprises an unmodified Y-type molecular sieve or a modified Y-type molecular sieve, clay and a binder; based on the total weight of the heavy oil catalyst, the content of the unmodified Y-type molecular sieve or the modified Y-type molecular sieve is 10-80%, the content of clay is 10-80%, and the content of the binder is 10-30%; the light oil catalyst comprises an unmodified ZSM-5 molecular sieve or a modified ZSM-5 molecular sieve, clay and a binder, based on the total weight of the catalyst, the content of the unmodified ZSM-5 molecular sieve or the modified ZSM-5 molecular sieve is 10-60%, the content of clay is 10-80%, and the content of the binder is 10-30%.

2. The catalytic conversion method according to claim 1, wherein The particle size and density of the first catalyst are both greater than those of the second catalyst.

3. The catalytic conversion method according to claim 1, wherein the first catalyst contains 90-100% by mass of a heavy oil catalyst and 0-10% by mass of a light oil catalyst; the second catalyst contains 0-10% by mass of a heavy oil catalyst and 90-100% by mass of a light oil catalyst.

4. The catalytic conversion method according to claim 3, wherein, Based on the total weight of the heavy oil catalyst, the content of the unmodified Y-type molecular sieve or the modified Y-type molecular sieve is 30-60%, the content of clay is 15-60%, and the content of the binder is 10-20%; The particle size range of the heavy oil catalyst is 60 - 250 μm, and the particle density is 1150 - 1600 kg / m 3 .

5. The catalytic conversion method according to claim 4, wherein The particle size range of the heavy oil catalyst is 80 to 200 μm, and the particle density is 1300 to 1500 kg / m 3 .

6. The catalytic conversion method according to any one of claims 3-5, wherein based on the total weight of the catalyst, the content of the unmodified ZSM-5 molecular sieve or the modified ZSM-5 molecular sieve is 20-50%, the content of clay is 20-70%, and the content of the binder is 10-20%. The particle size range of the light oil catalyst is 10 to 100 μm, and the particle density is 800 to 1200 kg / m 3 .

7. The catalytic conversion method according to claim 6, wherein, The particle size range of the light oil catalyst is 30 to 80 μm, and the particle density is 900 to 1050 kg / m 3 .

8. The catalytic conversion method according to claim 1, wherein, The first regeneration zone and the second regeneration zone are respectively arranged in a first regenerator and a second regenerator. The second regeneration zone is arranged in the cavity of the first regenerator, and the second regenerator is arranged in the first regeneration zone. Both the first regeneration zone and the second regeneration zone adopt complete regeneration.

9. The catalytic conversion method according to claim 1, wherein The regeneration temperature in the first regeneration zone is 660 to 720 °C, the catalyst distribution density is 50 to 400 kg / m 3 , and the main air residence time is 0.5 to 20 s; The regeneration temperature of the second regeneration zone is 670 to 730 °C, the catalyst distribution density is 30 to 350 kg / m 3 , and the main air residence time is 0.5 to 15 s.

10. The catalytic conversion method according to claim 9, wherein, The regeneration temperature of the first regeneration zone is 680 to 700 °C, the catalyst distribution density is 100 to 300 kg / m 3 , and the main air residence time is 2 to 10 s; The regeneration temperature of the second regeneration zone is 690 - 710 °C, the catalyst distribution density is 80 - 250 kg / m 3 , and the main air residence time is 2 - 10 s.

11. The catalytic conversion method according to claim 1, wherein, The reaction temperature in the first riser reaction zone is 500 - 620 °C; the catalyst-to-oil ratio is 1 - 15; the reaction time is 1 - 10 seconds. The reaction temperature in the second riser reaction zone is 520 - 640 °C, the catalyst-to-oil ratio is 2 - 20; the reaction time is 1 - 15 seconds.

12. The catalytic conversion method according to claim 11, wherein, The reaction temperature in the first riser reaction zone is 520 - 600 °C; the catalyst-to-oil ratio is 2 - 10; the reaction time is 2 - 8 seconds. The reaction temperature in the second riser reaction zone is 540 - 620 °C, the catalyst-to-oil ratio is 4 - 15; the reaction time is 2 - 10 seconds.

13. The catalytic conversion method according to claim 1, wherein The hydrotreated diesel is a product obtained by hydrotreating a mixture of one or more selected from straight-run diesel, catalytic cracking diesel, coking diesel, and hydrocracking diesel. The content of bicyclic aromatic hydrocarbons in the hydrotreated diesel is not more than 20% by weight. The catalytic conversion method further includes separating a diesel fraction from the oil-gas product in step S3, hydrogenating it, and returning it to step S1.

14. The catalytic conversion method according to claim 13, wherein The content of bicyclic aromatic hydrocarbons in the hydrotreated diesel is not more than 10% by weight.

15. A catalytic conversion system for producing light olefins and light aromatics from hydrotreated diesel, characterized in that, For the catalytic conversion method according to any one of claims 1 - 14, the catalytic conversion system includes a first riser reaction zone, a second riser reaction zone, a settler, a catalyst separation device, and a regenerator; the upper end of the first riser reaction zone is connected to the lower end of the second riser reaction zone. The upper end of the second riser reaction zone is connected to the lower end of the settler; a gas-solid separation device is also arranged in the settler. The lower end of the settler is further connected to a stripping vessel; the lower part of the stripping vessel has a mixed spent catalyst outlet. The catalyst separation device includes a primary catalyst separator and a secondary catalyst separator. The primary catalyst separator has a material inlet communicating with the mixed spent catalyst outlet, a first spent catalyst outlet, and a gas-solid mixture outlet. The secondary catalyst separator has a logistics inlet communicating with the gas-solid mixture outlet of the primary catalyst separator, a second spent catalyst outlet, and an oil-gas delivery outlet. The regenerator includes a first regenerator and a second regenerator. The second regenerator is arranged in the cavity of the first regenerator. A first regeneration zone is arranged in the first regenerator, and a second regeneration zone is arranged in the second regenerator. There is a first spent catalyst transfer connection between the first spent catalyst outlet and the first regeneration zone; there is a second spent catalyst transfer connection between the second spent catalyst outlet and the second regeneration zone; there is a first regenerated catalyst transfer connection between the first regeneration zone and the first riser reaction zone; there is a second regenerated catalyst transfer connection between the second regeneration zone and the second riser reaction zone.

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