Process for the production of renewable hydrocarbon fuels

Abstract

This invention relates to the field of organic synthesis technology and discloses a method for preparing renewable hydrocarbon fuels. The method includes contacting an ethylene-containing raw material with a first polymerization catalyst to conduct a first-stage polymerization reaction, obtaining a mixed product stream; the temperature of the first-stage polymerization reaction is not higher than 60°C; the first polymerization catalyst comprises: formula (1), where Me is any one of the transition metals, and R is selected from H or C1-C4 alkyl groups; a co-catalyst is also added to the first-stage polymerization reaction, selected from diethylaluminum chloride and / or methylaluminoxane; the mixed product stream is separated to obtain ethylene, butene-rich streams, and the first polymerization catalyst; the butene-rich stream is contacted with a second polymerization catalyst to conduct a second-stage polymerization reaction; the temperature of the second-stage polymerization reaction is not higher than 250°C; the product obtained from the second-stage polymerization reaction is sequentially subjected to gas-liquid separation and hydrogenation treatment. This method solves the problem of excessively high reaction temperature and energy consumption in the preparation of combustible hydrocarbons from ethylene.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, and more specifically to a method for preparing renewable hydrocarbon fuels. Background Technology

[0002] Against the backdrop of dwindling fossil fuel resources, the importance of renewable hydrocarbon fuels is self-evident, especially renewable gasoline, aviation fuel, and diesel used in the transportation sector. Among these, the rapid development of the aviation industry will lead to a continuous increase in greenhouse gas emissions and their proportion. Adopting sustainable aviation fuel (SAF) is a major measure for emissions reduction in the aviation industry. Compared to fossil fuels, SAF significantly reduces carbon emissions over its entire life cycle, achieving a reduction of up to 80%.

[0003] Ethanol, as a feedstock for renewable hydrocarbon fuels, mainly originates from the fermentation of bio-based sugars and starches or from the production of syngas from industrial waste. It boasts advantages such as abundant and renewable sources. However, due to its low energy density, hygroscopicity, and corrosiveness, ethanol cannot be used as aviation fuel or in high-compression engines; it can only be added in small quantities to gasoline for use in small cars. Therefore, converting ethanol into a high-energy-density, oxygen-free hydrocarbon fuel compatible with existing infrastructure is of practical significance. The dehydration of ethanol to produce ethylene is a relatively mature process, with a reaction temperature of 200-300℃. In this process, the ethanol conversion rate is over 97%, and the ethylene selectivity is over 96%. Further polymerization of ethylene into higher carbon olefins has been extensively studied. Among them, CN107148461 discloses a system and method for converting ethylene feedstock into hydrocarbon fuels. This patent involves passing the ethylene-containing feedstock through a Ni catalyst supported on an aluminosilicate substrate for the first step of polymerization, followed by a second step of polymerization through a solid acid catalyst, yielding C8... + It contains up to 77% jet fuel and diesel fuel. It also boasts a higher C8 content compared to the one-step process. + The yield is improved while avoiding the high reaction temperature (greater than 300℃) and excessively high aromatic content (greater than 60%) caused by direct ethanol polymerization. However, this two-stage polymerization process still faces the problems of excessively high reaction temperatures (40-220℃ for the first polymerization and 150-350℃ for the second polymerization) and excessively high energy consumption, resulting in hydrocarbon fuels with a much higher yield than those from fossil fuels on the market. US12157862B2 reports a method for preparing aviation fuel containing 8-25% aromatics using a mixture of low-carbon alcohols and water as raw materials through a solid acid-graded catalyst. This process also suffers from the problem of excessively high reaction temperatures (290-350℃). Therefore, new catalysts and reaction processes are needed to produce lower-cost renewable hydrocarbon fuels. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of excessively high reaction temperature and high energy consumption in the preparation of combustible hydrocarbon fuels from ethylene in the existing technology, and to provide a method for preparing renewable hydrocarbon fuels. This method solves the problems of excessively high reaction temperature and high energy consumption in the preparation of combustible hydrocarbons from ethylene.

[0005] To achieve the above objectives, the present invention provides a method for preparing renewable hydrocarbon fuel, comprising: (1) The ethylene-containing raw material and the first polymerization catalyst are brought into contact to carry out the first stage of polymerization reaction to obtain a mixed product stream; the temperature of the first stage of polymerization reaction is not higher than 60℃; The first polymerization catalyst comprises a metal complex as shown in formula (1), Equation (1), Wherein, Me is any one of the transition metals, and each R is independently selected from H and any one of C1-C4 alkyl groups; a co-catalyst is also added to the first polymerization reaction, and the co-catalyst is selected from diethylaluminum chloride and / or methylaluminoxane; (2) The mixed product streams are separated to obtain ethylene, butene-rich streams and the first polymerization catalyst; (3) The butene-rich stream is brought into contact with the second polymerization catalyst to carry out the second stage polymerization reaction; The second polymerization catalyst includes a silica-alumina molecular sieve; the temperature of the second-stage polymerization reaction does not exceed 250℃; (4) The products obtained from the second polymerization reaction are subjected to gas-liquid separation and hydrogenation treatment in sequence.

[0006] This invention, through the aforementioned technical solution, employs two different polymerization catalysts to sequentially carry out the first and second stage polymerization reactions, thereby reducing the reaction temperature of both stages and overcoming the problems of excessively high reaction temperatures and high energy consumption in the existing technology for producing combustible hydrocarbon fuels from ethylene. Furthermore, by adjusting the process parameters, it can achieve three operating conditions: high-yield gasoline (C5-C10), aviation kerosene (C8-C16), and diesel (C10-C22). Attached Figure Description

[0007] Figure 1 This is a schematic diagram of a renewable hydrocarbon fuel preparation apparatus according to one embodiment of the present invention.

[0008] Explanation of reference numerals in the attached figures 101. First stage polymerization reactor; 102. Distillation column one; 103. Butene-rich stream storage tank; 201. Second stage polymerization reactor; 202. Butene distillation column; 301. Hydrogenation reactor; 302. Distillation column two; 1. Ethylene feed line; 2. Co-catalyst feed line; 3. First polymerization catalyst feed line; 4. First stage polymerization reactor outlet line; 5. Distillation column one top outlet line; 6. Distillation column one bottom outlet line one; 7. Distillation column one bottom outlet line two; 8. Butene-rich material storage tank inlet line; 9. Butene-rich material storage tank outlet line; 10. Second stage polymerization reactor gas inlet line; 11. Second stage polymerization reactor outlet line; 12. Butene distillation column top outlet line; 13. Butene distillation column bottom outlet line; 14. Hydrogenation reactor inlet gas line; 15. Hydrogenation reactor outlet line; 16. Low-carbon alkane outlet line; 17. Gasoline outlet line; 18. Kerosene outlet line; 19. Diesel outlet line. Detailed Implementation

[0009] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0010] This invention provides a method for preparing renewable hydrocarbon fuel, comprising: (1) The ethylene-containing raw material and the first polymerization catalyst are brought into contact to carry out the first stage of polymerization reaction to obtain a mixed product stream; the temperature of the first stage polymerization reaction is not higher than 60℃; The first polymerization catalyst comprises a metal complex as shown in formula (1), Equation (1), Wherein, Me is any one of the transition metals, and each R is independently selected from H and any one of C1-C4 alkyl groups; a co-catalyst is also added to the first polymerization reaction, and the co-catalyst is selected from diethylaluminum chloride and / or methylaluminoxane; (2) The mixed product streams are separated to obtain ethylene, butene-rich streams and the first polymerization catalyst; (3) The butene-rich stream is brought into contact with the second polymerization catalyst to carry out the second stage polymerization reaction; The second polymerization catalyst includes a silica-alumina molecular sieve; the temperature of the second-stage polymerization reaction does not exceed 250℃; (4) The products obtained from the second polymerization reaction are subjected to gas-liquid separation and hydrogenation treatment in sequence.

[0011] In existing technologies, the direct production of combustible hydrocarbon fuels from ethylene typically involves reactions at temperatures above 300°C, resulting in high energy consumption and rapid catalyst deactivation. This invention employs two different polymerization catalysts to sequentially perform the first and second polymerization reactions, thereby reducing the reaction temperatures of both stages and enabling the production of high-yield gasoline, jet fuel, and diesel fuel through adjustment of reaction process parameters.

[0012] This invention does not particularly limit the source of the ethylene-containing raw materials, as long as the technical objective of the invention can be achieved. According to some preferred embodiments of the invention, the ethylene-containing raw materials are obtained from bio-based sugars and alcohols derived from starch fermentation through a dehydration process.

[0013] According to the present invention, preferably, in step (1), the mass ratio of the ethylene-containing raw material to the metal complex is 5000-30000:1; more preferably, it is 8000-25000:1.

[0014] According to the present invention, preferably, the temperature of the first polymerization reaction is 10-60°C and the pressure is 1-4 MPa. More preferably, the temperature of the first polymerization reaction is 15-45°C and the pressure is 2-4 MPa; even more preferably, the temperature of the first polymerization reaction is 25-45°C and the pressure is 3-4 MPa.

[0015] In this invention, the conditions of the first polymerization reaction being within the above-mentioned preferred range are beneficial to improving the catalytic activity of the catalyst, increasing the yield of butene-rich products, and increasing the proportion of isobutene products.

[0016] According to the present invention, preferably, the metal complex is provided by a complex solution having a concentration of 0.5 × 10⁻⁶. -5 Up to 1×10 -4 g / g, more preferably 0.8×10 g / g. -5 Up to 0.7×10 -4 g / g.

[0017] In this invention, the concentration of the complex solution within the above-mentioned preferred range is beneficial to the dissolution and dispersion of the catalyst, fully exerting the catalytic activity of the catalyst and improving the conversion rate of ethylene in a single pass.

[0018] In this invention, the first polymerization catalyst comprises a metal complex as shown in formula (1). Equation (1), Wherein, Me is any of the transition metals, and each R is independently selected from H and any of the C1-C4 alkyl groups.

[0019] In the metal complex provided by the present invention, preferably, Me in formula (1) is at least one of Ni, Co and Fe, and more preferably, Me is Ni.

[0020] Preferably, each R is independently selected from methyl, ethyl, isopropyl or tert-butyl, more preferably each R is independently tert-butyl.

[0021] In this invention, the use of the above-mentioned preferred composition of the metal complex is beneficial to increasing the yield of butene products and the proportion of isobutylene in the products.

[0022] In this invention, there are no particular limitations on the preparation process of the first polymerization catalyst, as long as the technical objective of this invention can be achieved.

[0023] According to some preferred embodiments of the present invention, the preparation method of the first polymerization catalyst includes: S1. Mix N,N'-bis(2-aminoethyl)-1,4-butanediamine solution with salicylaldehyde compound solution as shown in formula (2), stir and reflux, and then recrystallize to obtain ligand; Equation (2), S2. Mix the solution containing the ligand with the metal chloride, and then react and recrystallize.

[0024] In this invention, there are no particular limitations on the mixing method in S1, as long as it achieves the technical objective of this invention. According to some preferred embodiments of the invention, the mixing method in S1 includes: using a constant pressure funnel, slowly adding a salicylaldehyde compound solution as shown in formula (2) dropwise to an N,N'-bis(2-aminoethyl)-1,4-butanediamine solution. According to some preferred embodiments of the invention, the mixing temperature is 20-60°C.

[0025] In this invention, there is no particular limitation on the amount of salicylaldehyde compound and N,N'-bis(2-aminoethyl)-1,4-butanediamine solution used, as long as the technical objective of this invention is achieved. According to some preferred embodiments of this invention, the mass ratio of the salicylaldehyde compound and the N,N'-bis(2-aminoethyl)-1,4-butanediamine solution is 2-3:1.

[0026] In this invention, there are no particular limitations on the conditions for stirring and reflux in S1, as long as the technical objective of this invention is achieved. According to some preferred embodiments of this invention, the conditions for stirring and reflux include: under an inert atmosphere, at a temperature of 90-150°C, for a time of 4-8 hours.

[0027] In this invention, there are no particular limitations on the mixing method in S2, as long as it achieves the technical objective of this invention. According to some preferred embodiments of this invention, the mixing method in S2 includes: adding the metal chloride solution dropwise to the ligand-containing solution while stirring at room temperature.

[0028] In this invention, the reaction conditions described in S2 are not particularly limited, as long as they achieve the technical objective of this invention. According to some preferred embodiments of this invention, the reaction conditions include a temperature of 35-100°C and a time of 3-7 hours under stirring conditions.

[0029] According to the present invention, in step (1), a co-catalyst is also added to the first polymerization reaction. Preferably, the co-catalyst is selected from diethylaluminum chloride (Et2AlCl) and / or methylaluminoxane (MAO).

[0030] In this invention, the use of the above-mentioned preferred co-catalyst is beneficial to activating the main catalyst, improving the polymerization activity of the catalyst, and removing impurities such as water and oxygen that are detrimental to the reaction.

[0031] According to the present invention, preferably, the molar ratio of the co-catalyst (calculated as a metal element) to the molar ratio of the transition metal in the metal complex is 100-2000:1. More preferably, it is 400-1500:1.

[0032] In this invention, the amount of the co-catalyst within the above-mentioned preferred range is beneficial to activating the main catalyst, while avoiding over-activation of the main catalyst, thereby improving the polymerization activity of the main catalyst and increasing the yield of the butene-rich product.

[0033] According to the present invention, preferably, the co-catalyst is provided by a co-catalyst solution with a concentration of 0.1-1.5 mol / L.

[0034] In this invention, the concentration of the co-catalyst solution within the above-mentioned preferred range is beneficial for maintaining good fluidity of the solution, which is beneficial for pump delivery and metering.

[0035] This invention does not impose any particular limitation on the solvent of the co-catalyst solution, as long as it achieves the technical objective of this invention. According to some preferred embodiments of this invention, the solvent is selected from at least one of hexaane, heptane, octane, nonane, toluene, gasoline, etc.

[0036] According to the present invention, preferably, in step (1), the ethylene-containing raw material and the first polymerization catalyst are fed into the reactor for the first stage of polymerization reaction by a bottom feeding method.

[0037] In this invention, the bottom-feed method facilitates full contact between ethylene and the catalyst, increases the probability of ethylene polymerization, and increases the yield of butene-rich products.

[0038] In this invention, there are no particular limitations on the separation conditions described in step (2), as long as the unreacted ethylene and unreacted co-catalyst can be recycled back to the bottom inlet of 101, the first polymerization catalyst and the deactivated co-catalyst can be separated by precipitation from the bottom of the tower, and the butene-rich product can enter the second polymerization reactor 201 for secondary polymerization. Preferably, in step (2), the separation conditions include: pressure 0.1-1 MPa and tower bottom temperature 80-150°C.

[0039] According to the present invention, preferably, in step (1), the mass fraction of butene in the mixed product stream, based on the total amount of olefins, is 40-90%, more preferably 50-90%; and the mass fraction of hexene is 2-5%, more preferably 3-5%. In the present invention, the olefins in the mixed product stream include unreacted raw material ethylene and the first-stage polymerization products butene and hexene, wherein the butene includes 1-butene (butene-1), 2-butene (butene-2), and isobutene. In the present invention, the butene content in the mixed stream within the above-mentioned preferred range is beneficial for the design of the second polymerization catalyst because the raw material source composition is relatively fixed, allowing for targeted adjustment of the acid type and acid distribution of the catalyst to achieve optimal polymerization effect.

[0040] Preferably, in step (1), the mass fraction of isobutylene in the mixed product stream is 20-70%, more preferably 40-70%, based on the total amount of olefins.

[0041] In this invention, the content of isobutylene in the mixed product stream within the above-mentioned preferred range is beneficial to reducing the reaction temperature of the second polymerization catalyst, reducing carbon deposition on the catalyst, and extending the service life of the catalyst.

[0042] According to the present invention, preferably, step (2) further includes: returning the separated ethylene to step (1).

[0043] According to the present invention, preferably, in the second polymerization catalyst, the silica-alumina molecular sieve is selected from any one of Y-molecular sieve, ZSM-5 molecular sieve, MCM-41 molecular sieve, ZSM-22 molecular sieve, β molecular sieve, SAPO-11 molecular sieve, and SAPO-34 molecular sieve.

[0044] This invention does not impose a particular limitation on the silicon-to-aluminum ratio of the silicon-aluminum molecular sieve, as long as the technical objective of this invention is achieved. According to some preferred embodiments of this invention, the molar ratio of silicon oxide to alumina in the silicon-aluminum molecular sieve is 20-100:1.

[0045] In this invention, the use of the above-mentioned preferred silica-alumina molecular sieve is beneficial for the polymerization of butene-rich streams to prepare high-carbon olefins, and for the synthesis of gasoline, jet fuel and diesel fuel.

[0046] According to the present invention, preferably, the second polymerization catalyst further includes an auxiliary agent, an active metal component, and a binder, wherein the auxiliary agent is P and / or S; the active metal component is selected from at least one of Ni, Zr, La, Ti, and Fe, preferably a combination of two, such as Ni / Zr, Ni / La, Ni / Ti, or Ni / Fe.

[0047] This invention does not impose any particular limitation on the type of binder in the second polymerization catalyst; conventional binders in the art can be used. According to some preferred embodiments of the invention, the binder is selected from at least one of alumina, amorphous aluminosilicate, and kaolin.

[0048] According to the present invention, preferably, the content of molecular sieve is 60-90 wt% based on the total amount of the second polymerization catalyst.

[0049] According to the present invention, preferably, in the second polymerization catalyst, the content of the auxiliary component is 0.2-0.8 wt% and the content of the active metal component is 0.2-1.5 wt%.

[0050] According to the present invention, preferably, the content of the binder in the second polymerization catalyst is 10-40 wt%.

[0051] In this invention, there are no particular limitations on the preparation process of the second polymerization catalyst, as long as the technical objective of this invention can be achieved.

[0052] According to the present invention, preferably, the second polymerization reaction is carried out in the presence of a carrier gas selected from nitrogen or an inert gas, and the volume ratio of the carrier gas to the butene-rich stream is 100-1600.

[0053] According to the present invention, preferably, the reaction temperature of the second polymerization reaction is 140-250°C, the reaction pressure is 2-6 MPa, and the liquid hourly space velocity of the butene-rich stream is 0.2-2.5 h⁻¹. -1 .

[0054] In this invention, by further adjusting the process parameters, three operating conditions can be achieved: high production of gasoline (C5-C10), aviation kerosene (C8-C16), and diesel (C10-C22).

[0055] According to some preferred embodiments of the present invention, the temperature of the second-stage polymerization reaction is 140-180°C, the volume ratio of carrier gas to butene-rich stream is 600-1200, the reaction pressure is 2-3.5 MPa, and the space velocity of the butene-rich stream is 0.7-1.5 h⁻¹. -1To obtain gasoline as the primary fuel.

[0056] More preferably, the second-stage polymerization reaction is carried out at a temperature of 145-175°C, a volume ratio of carrier gas to butene-rich stream of 700-1000, a reaction pressure of 2-3.5 MPa, and a space velocity of 0.8-1.3 h⁻¹ for the butene-rich stream. -1 To obtain gasoline as the primary fuel.

[0057] In this invention, "gasoline-based" means that the yield of gasoline (C5-C10) in the product is above 70%.

[0058] According to other preferred embodiments of the present invention, the temperature of the second-stage polymerization reaction is 160-200°C, the volume ratio of carrier gas to butene-rich stream is 400-800, the reaction pressure is 2.5-4.5 MPa, and the liquid hourly space velocity (LHSV) of the butene-rich stream is 0.5-1 h⁻¹. -1 To obtain fuel primarily composed of aviation kerosene. More preferably, the second-stage polymerization reaction temperature is 170-190℃, the volume ratio of carrier gas to butene-rich stream is 450-800, the reaction pressure is 3-4.5 MPa, and the liquid hourly space velocity (LHSV) of the butene-rich stream is 0.6-0.9 h⁻¹. -1 To obtain fuel, primarily jet fuel.

[0059] In this invention, "mainly aviation kerosene" means that the yield of aviation kerosene (C8-C16) in the product is above 70%.

[0060] According to other preferred embodiments of the present invention, the temperature of the second-stage polymerization reaction is 180-240°C, the volume ratio of carrier gas to butene-rich stream is 200-600, the reaction pressure is 3.5-6 MPa, and the space velocity of the butene-rich stream is 0.3-0.7 h⁻¹. -1 To obtain diesel-based fuel. More preferably, the second-stage polymerization reaction temperature is 190-230℃, the volume ratio of carrier gas to butene-rich stream is 250-550, the reaction pressure is 4-6 MPa, and the liquid hourly space velocity (LHSV) of the butene-rich stream is 0.4-0.6 h⁻¹. -1 To obtain diesel as the primary fuel.

[0061] In this invention, "diesel-based" means that the yield of diesel (C10-C22) in the product is above 70%.

[0062] According to the present invention, preferably, the hydrogenation treatment is carried out in the presence of a hydrogenation catalyst selected from Ni-based catalysts or noble metal catalysts. According to some preferred embodiments of the present invention, the noble metal catalyst is Pd and / or Pt-based.

[0063] In this invention, the use of the above-mentioned preferred hydrogenation catalyst is beneficial for the hydrogenation of olefins.

[0064] According to the present invention, preferably, the hydrotreating temperature is 80℃-180℃, the pressure is 1-5MPa, the hydrogen-to-oil volume ratio is 300-1500, and the feed space velocity is 0.5-2.5h. -1 .

[0065] In this invention, the above-mentioned preferred hydrogenation conditions facilitate the near-complete hydrogenation of olefin components, thus meeting the standards for combustible hydrocarbon fuels.

[0066] This invention does not impose any particular limitation on the apparatus used in the above preparation method. Those skilled in the art can select and combine suitable equipment based on the reaction conditions required in the above preparation method. According to some preferred embodiments of the invention, such as... Figure 1 As shown, the system used in the preparation method includes: 101, a first-stage polymerization reactor; 102, a first distillation column; 103, a butene-rich stream storage tank; 201, a second-stage polymerization reactor; 202, a butene distillation column; 301, a hydrogenation reactor; 302, a second distillation column; 1, an ethylene feed line; 2, a co-catalyst feed line; 3, a first polymerization catalyst feed line; 4, an outlet line of the first-stage polymerization reactor; and 5, a top outlet line of the first distillation column. 6. Bottom outlet pipeline of distillation column 1; 7. Bottom outlet pipeline of distillation column 1 (second line); 8. Inlet pipeline of butene-rich material storage tank; 9. Outlet pipeline of butene-rich material storage tank; 10. Gas inlet pipeline of the second-stage polymerization reactor; 11. Outlet pipeline of the second-stage polymerization reactor; 12. Top outlet pipeline of butene distillation column; 13. Bottom outlet pipeline of butene distillation column; 14. Inlet gas pipeline of hydrogenation reactor; 15. Outlet pipeline of hydrogenation reactor; 16. Low-carbon alkane outlet pipeline; 17. Gasoline outlet pipeline; 18. Kerosene outlet pipeline; 19. Diesel outlet pipeline.

[0067] The bottom of the first polymerization reactor 101 is equipped with an ethylene feed line 1, a co-catalyst feed line 2, and a first polymerization catalyst feed line 3, which are used to feed the ethylene-containing raw material, the co-catalyst solution, and the first polymerization catalyst solution into the first polymerization reactor 101, respectively. The top of the first polymerization reactor 101 is connected to a distillation column 102 via a first polymerization reactor outlet line 4. The mixed product stream from reactor 101 is sent to the distillation column 102 for separation through the first polymerization reactor outlet line 4 to obtain ethylene, butene-rich streams, and the first polymerization catalyst solution. A polymerization catalyst is used. A distillation column 102 is equipped with a top outlet pipeline 5. The obtained ethylene returns to the ethylene feed pipeline 1 via the top outlet pipeline 5 to continue the first stage of polymerization. The bottom of the distillation column 102 is also connected to a bottom outlet pipeline 6 and a bottom outlet pipeline 7. After the reaction, the first polymerization catalyst and the deactivated co-catalyst precipitate and are discharged from the bottom outlet pipeline 7. The undeactivated co-catalyst and solvent enter the first stage polymerization reactor 101 via the bottom outlet pipeline 6 for reuse. The distillation column 102 and the butene-rich material storage tank 103 are connected via a butene-rich material storage tank inlet pipeline 8. The butene-rich storage tank is connected to the second-stage polymerization reactor 201 via the butene-rich stream storage tank outlet pipeline 9. The second-stage polymerization reactor 201 is also connected to the second-stage polymerization reactor gas inlet pipeline 10. The butene-rich stream from the distillation column 102 is mixed with N2 introduced through the second-stage polymerization reactor gas inlet pipeline 10 via the butene-rich stream storage tank outlet pipeline 9 before entering the second-stage polymerization reactor 201 for the second-stage polymerization reaction. The bottom of the reactor 201 is connected to the butene distillation column 202 via the second-stage polymerization reactor outlet pipeline 11, which is used to send the product from the second-stage polymerization reactor 201 into the butene distillation column 202. The product from the second-stage polymerization reactor 201 is separated by the butene distillation column 202, and the unreacted C4 olefins and nitrogen are recycled to the feed inlet of the second-stage polymerization reactor 201 and fresh feed through the top outlet pipeline 12 of the butene distillation column for further reaction. The bottom of the butene distillation column 202 is connected to the hydrogenation reactor 301 via the bottom outlet pipeline 13. The hydrogenation reactor 301 is also connected to the inlet gas pipeline 14. The target oil product exiting the bottom of the butene distillation column 202 mixes with hydrogen gas introduced through the bottom outlet pipeline 13 and the inlet gas pipeline 14 before entering the hydrogenation reactor 301 for hydrogenation reaction via a hydrogenation catalyst. The hydrogenated product enters the second distillation column 302 via the outlet pipeline 15 of the hydrogenation reactor. The second distillation column 302 is also connected to the low-carbon alkane outlet pipeline 16, gasoline outlet pipeline 17, kerosene outlet pipeline 18, and diesel outlet pipeline 19.

[0068] This invention overcomes the problems of excessively high reaction temperatures and energy consumption in the existing technology for producing combustible hydrocarbon fuels from ethylene. By developing two types of polymerization catalysts and innovating the process route, the reaction temperature of the two-stage polymerization catalysts is significantly reduced. Furthermore, through adjustment of process parameters, three operating conditions are achieved: high-yield gasoline (C5-C10), aviation kerosene (C8-C16), and diesel (C10-C22). This solves the problem of excessively high reaction temperatures and energy consumption in the production of combustible hydrocarbons from ethylene.

[0069] Preparation Example 1 Preparation of the first polymerization catalyst: A certain amount of N,N'-bis(2-aminoethyl)-1,4-butanediamine was dissolved in 50 mL of anhydrous methanol to obtain solution A. In another container, 4.12 g of 3,5-di-tert-butylsalicylaldehyde was dissolved in 30 mL of anhydrous methanol to obtain solution B. Then, solution B was slowly added dropwise to solution A using a constant pressure dropping funnel, maintaining the reaction system at 30 °C and continuously stirring during the addition. The mixture was then stirred and refluxed (120 °C) under an inert atmosphere for 12 h, recrystallized, and dried to obtain a bright yellow N,N'-bis(2-aminoethyl)-1,4-butanediamine solution-salicylimine ligand.

[0070] The N,N'-bis(2-aminoethyl)-1,4-butanediamine solution-salicylimine ligand (1 g) synthesized in the previous step was dissolved in 30 mL of anhydrous toluene and stirred until completely dissolved. A certain amount of nickel(II) chloride was dissolved in 10 mL of anhydrous methanol. Under stirring at room temperature, the methanol solution of the nickel salt was added dropwise to the toluene solution of the ligand. After the addition was complete, the reaction mixture was heated to 70 °C and refluxed and stirred at this temperature for 12 hours. Finally, after recrystallization and drying, the catalyst Cat.1 was obtained, with the structure shown in formula (1).

[0071] Preparation Example 2 Preparation of the second polymerization catalyst: 200g of ZSM-5 molecular sieve (molar ratio of silica to alumina: 60), 50g of boehmite, and 6g of guar gum powder were weighed and mixed in a kneader for 10min. Then, a certain amount of dilute phosphoric acid solution was added and kneaded again for 20min. The mixture was then extruded into strips in an extruder. Afterward, it was dried in an oven at 150℃ for 2h and calcined in a muffle furnace at 550℃ for 4h. The obtained molecular sieve support was impregnated in an aqueous solution of nickel nitrate hexahydrate and zirconium oxynitrate. Afterward, it was dried at 120℃ for 2h and calcined at 450℃ for 4h to obtain catalyst Cat.2, with a P content of 0.5wt%, a Ni loading of 0.45wt%, and a Zr content of 0.35wt% based on the support (100% basis).

[0072] Preparation Example 3 Preparation of the second polymerization catalyst: The method is the same as in Preparation Example 2, except that the Ni loading was increased to 0.8 wt% by adjusting the impregnation conditions of the support, thus obtaining catalyst Cat.3.

[0073] Comparative Preparation Example 1 The method is the same as in Preparation Example 1, except that 3,5-di-tert-butylsalicylaldehyde is replaced with 3,5-dichlorosalicylaldehyde to obtain catalyst DBCat.1.

[0074] Comparative Preparation Example 2 The method is the same as in Preparation Example 1, except that 3,5-di-tert-butylsalicylaldehyde is replaced with 5-methoxysalicylaldehyde to obtain catalyst DBCat.2.

[0075] Examples 1-1 to 1-9 Ethylene gas and a mass concentration of 1.3 × 10⁻⁶ -5 In Example 1, a solution of the first polymerization catalyst in isooctane and a 1.0 mol / L solution of diethylaluminum chloride in isooctane were introduced into the first polymerization reactor 101 from the bottom. The mass ratio of ethylene to the first polymerization catalyst was 18000:1. The reaction conditions and the material balance data obtained after the reaction are shown in Table 1 below.

[0076] Examples 1-10 The method is the same as in Examples 1-5, except that the materials all enter the reactor from the top of the first polymerization reactor 101. The reaction conditions and the material balance data obtained after the reaction are shown in Table 1 below.

[0077] Comparative Example 1-1 The method is the same as in Examples 1-5, except that DBCat.1 is used for testing.

[0078] Comparative Examples 1-2 The method is the same as in Examples 1-5, except that DBCat.2 is used for testing.

[0079] Comparative Examples 1-3 The method is the same as in Examples 1-5, except that no co-catalyst is added.

[0080] Table 1

[0081] Examples 2-1 to 2-12 The product of the first polymerization of ethylene obtained under the operating conditions of Examples 1-5 was refluxed through a distillation column to the first polymerization reactor 101 with unreacted ethylene components. The resulting butene, hexene, and nitrogen were mixed and then subjected to a secondary polymerization reaction in the second polymerization reactor 201 under the action of the second polymerization catalyst Cat.2. The reaction conditions and the material balance tables obtained after the reaction are shown in Tables 2-1, 2-2, and 2-3 below.

[0082] Example 2-13 The method is the same as in Examples 2-12, except that the butene-rich products obtained in Examples 1-9 were used as the raw material for the second polymerization. The material balance table after the reaction is shown in Table 2-3 below.

[0083] Example 2-14 The method is the same as in Examples 2-12, except that the temperature of the second polymerization reaction is 250°C, the pressure is 5 MPa, and the liquid hourly space velocity (LHSV) of the butene-rich stream is 0.4 h⁻¹. -1 The material balance table obtained after the reaction is shown in Table 2-3 below.

[0084] Example 2-15 The method is the same as in Examples 2-12, except that the second polymerization catalyst is Cat.3. The material balance table obtained after the reaction is shown in Table 2-3 below.

[0085] Example 2-16 The method is the same as in Examples 2-12, except that the liquid hourly space velocity (LHSV) is 0.8. The material balance table obtained after the reaction is shown in Table 2-3 below.

[0086] Comparative Example 2-1 The method is the same as in Examples 2-12, except that the butene-rich product obtained in Comparative Example 1-1 was used as the raw material for the second polymerization. The material balance table obtained after the reaction is shown in Table 2-3 below.

[0087] Comparative Example 2-2 The method is the same as in Examples 2-12, except that the butene-rich product obtained in Comparative Examples 1-2 was used as the raw material for the second polymerization. The material balance table obtained after the reaction is shown in Table 2-3 below.

[0088] Table 2-1

[0089] Table 2-2

[0090] Table 2-3

[0091] In Tables 2-1, 2-2, and 2-3, the C value is the volume ratio of carrier gas to butene-rich stream.

[0092] As can be seen from the results in Tables 2-1, 2-2, and 2-3, the embodiments of the two-stage polymerization process of the present invention have significant technical effects in maximizing the production of gasoline, jet fuel, and diesel fuel under different operating conditions, realizing the preparation of combustible hydrocarbon fuels from ethylene.

[0093] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing renewable hydrocarbon fuel, characterized in that, include: (1) The ethylene-containing raw material and the first polymerization catalyst are brought into contact to carry out the first stage of polymerization reaction to obtain a mixed product stream; The temperature of the first polymerization reaction should not exceed 60℃; The first polymerization catalyst comprises a metal complex as shown in formula (1), Equation (1), Wherein, Me is any one of the transition metals, and each R is independently selected from H and any one of C1-C4 alkyl groups; a co-catalyst is also added to the first polymerization reaction, and the co-catalyst is selected from diethylaluminum chloride and / or methylaluminoxane; (2) The mixed product streams are separated to obtain ethylene, butene-rich streams and the first polymerization catalyst; (3) The butene-rich stream is brought into contact with the second polymerization catalyst to carry out the second stage polymerization reaction; The second polymerization catalyst includes a silica-alumina molecular sieve; the temperature of the second-stage polymerization reaction does not exceed 250℃; (4) The products obtained from the second polymerization reaction are subjected to gas-liquid separation and hydrogenation treatment in sequence.

2. The preparation method according to claim 1, characterized in that, In step (1), the mass ratio of the ethylene-containing raw material to the metal complex is 5000-30000:1; And / or, the temperature of the first polymerization reaction is 10-60℃ and the pressure is 1-4MPa; And / or, the metal complex is provided by a complex solution with a concentration of 0.5 × 10⁻⁶. -5 Up to 1×10 -4 g / g.

3. The preparation method according to claim 1, characterized in that, Me is at least one of Ni, Co, and Fe, and each R is independently selected from methyl, ethyl, isopropyl, and tert-butyl.

4. The preparation method according to claim 1, characterized in that, The ratio of the molar amount of the co-catalyst, calculated as a metal element, to the molar amount of the transition metal in the metal complex is 100-2000:1; The co-catalyst is provided by a co-catalyst solution with a concentration of 0.1-1.5 mol / L.

5. The preparation method according to claim 4, characterized in that, In step (1), the ethylene-containing raw material, the first polymerization catalyst and the co-catalyst are fed into the reactor to carry out the first stage of polymerization reaction by bottom feeding. And / or, in step (1), the mass fraction of butene in the mixed product stream is 40-90% and the mass fraction of hexene is 2-5% based on the total amount of olefins; And / or, step (2) further includes: returning the separated ethylene to step (1).

6. The preparation method according to claim 5, characterized in that, In step (1), the mass fraction of isobutylene in the mixed product stream is 20-70% based on the total amount of olefins.

7. The preparation method according to claim 1, characterized in that, The silica-aluminum molecular sieve is selected from any one of the following: Y-molecular sieve, ZSM-5 molecular sieve, MCM-41 molecular sieve, ZSM-22 molecular sieve, β molecular sieve, SAPO-11 molecular sieve, and SAPO-34 molecular sieve. And / or, the second polymerization catalyst further includes an auxiliary component, an active metal component, and a binder, wherein the auxiliary component is selected from at least one of P and S; and the active metal component is selected from at least one of Ni, Zr, La, Ti, and Fe. Based on the total amount of the second polymerization catalyst, the molecular sieve content is 60-90 wt%, the auxiliary component content (in elemental terms) is 0.2-0.8 wt%, the active metal component content is 0.2-1.5 wt%, and the binder content is 10-40 wt%.

8. The preparation method according to claim 1, characterized in that, The second polymerization reaction is carried out in the presence of a carrier gas, which is selected from nitrogen or an inert gas, and the volume ratio of the carrier gas to the butene stream is 100-1600. And / or, the reaction temperature of the second polymerization reaction is 140-250℃, the reaction pressure is 2-6MPa, and the liquid hourly space velocity of the butene-rich stream is 0.2-2.5h. -1 .

9. The preparation method according to claim 8, characterized in that, The second-stage polymerization reaction is carried out at a temperature of 140-180℃, with a volume ratio of carrier gas to butene-rich stream of 600-1200, a reaction pressure of 2-3.5 MPa, and a liquid hourly space velocity (LHSV) of 0.7-1.5 h⁻¹ for the butene-rich stream. -1 To obtain gasoline as the primary fuel; or, The second-stage polymerization reaction is carried out at a temperature of 160-200℃, with a volume ratio of carrier gas to butene-rich stream of 400-800, a reaction pressure of 2.5-4.5 MPa, and a liquid hourly space velocity (LHSV) of 0.5-1 h⁻¹ for the butene-rich stream. -1 In order to obtain fuel, primarily jet fuel; The second-stage polymerization reaction is carried out at a temperature of 180-230℃, with a volume ratio of carrier gas to butene-rich stream of 200-600, a reaction pressure of 3.5-6 MPa, and a liquid hourly space velocity (LHSV) of 0.3-0.7 h⁻¹ for the butene-rich stream. -1 To obtain diesel as the primary fuel.

10. The preparation method according to claim 1, characterized in that, The hydrogenation process is carried out in the presence of a hydrogenation catalyst, which is selected from Ni-based catalysts or noble metal catalysts. The hydrotreating process is carried out at a temperature of 80℃-180℃, a pressure of 1-5MPa, a hydrogen-to-oil volume ratio of 100-1000, and a feed space velocity of 0.5-2.5h. -1 .

Images