A catalyst for the oligomerization of butenes to produce long chain olefins, its preparation and use

Abstract

This invention discloses a catalyst, its preparation method, and its application for the oligomerization of butene to prepare long-chain olefins, belonging to the fields of comprehensive resource utilization and energy chemical technology. The catalyst preparation method includes: adding HZSM-5 molecular sieve to a lithium nitrate solution or a citric acid solution, heating and stirring, taking the solid product, centrifuging and washing it, and then drying and calcining it to obtain the modified HZSM-5 molecular sieve catalyst. This invention provides a micro-mesoporous molecular sieve catalyst with high activity and long-chain olefin selectivity for the oligomerization process of butene, achieving a butene conversion rate of 96.49%, a C8-C18 yield of 79.63%, of which the C12-C18 yield reaches 23.31%, and it also exhibits good stability.

Description

Technical Field

[0001] This invention belongs to the fields of comprehensive utilization of resources and energy chemical technology, specifically relating to a catalyst, preparation method and application for the oligomerization of butene to prepare long-chain olefins. Background Technology

[0002] In the petrochemical industry, C4 olefins are a crucial chemical resource. Catalytic cracking (FCC) and steam cracking (SC) of heavy oil processes generate large quantities of usable C4 fractions (such as n-butane, n-butene, butadiene, and isobutene). The direct emission of large amounts of untreated C4 fractions poses a significant threat to the atmosphere, water, soil, ecosystems, and human health, and exacerbates global warming. Therefore, there is growing interest in utilizing C4 olefins through oligomerization processes for resource reuse, which is of great importance in addressing the challenges of C4 fraction processing and environmental pollution.

[0003] Butene oligomerization is a process in which butene, under the action of an acidic catalyst, forms a carbocation, which then undergoes an electrophilic addition reaction with another butene molecule, leading to carbon chain growth. This process is repeated continuously to generate long-chain alkanes. Currently, due to the growing market demand for high-quality fuels, butene oligomerization to produce long-chain alkanes is a very attractive production route. This process can efficiently and sustainably produce high-quality, environmentally friendly liquid fuels that are low in aromatics and sulfur-free, enabling the high-value utilization of low-carbon olefin products.

[0004] Currently, the key to research on butene oligomerization lies in developing highly selective, long-lived, and highly active catalysts and suitable catalytic processes. Traditional olefin oligomerization processes suffer from numerous problems, including insufficient catalyst activity, selectivity, and stability, as well as complex and costly catalyst preparation. For example, traditional Ziegler-Natta catalysts offer limited control over product distribution in olefin oligomerization and are easily affected by impurities. Therefore, finding superior catalysts and processes to achieve efficient, environmentally friendly, and economical butene oligomerization is of significant practical importance. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a catalyst, preparation method and application for the oligomerization of butene to prepare long-chain olefins, thereby solving the problems in the prior art.

[0006] Methods for preparing catalysts for the oligomerization of butene to long-chain olefins include: HZSM-5 was added to a lithium nitrate solution for ion exchange, followed by centrifugation, washing, drying, and calcination to obtain a modified HZSM-5 molecular sieve catalyst. Alternatively, HZSM-5 can be added to a citric acid solution, heated and stirred, then centrifuged, washed, dried and calcined to obtain a modified HZSM-5 molecular sieve catalyst.

[0007] Furthermore, the concentration of the lithium nitrate solution is 0.01 M to 0.5 M.

[0008] Furthermore, the ion exchange process is as follows: heating and stirring at 60~80 °C for 6~8 h.

[0009] Furthermore, the drying and calcining step includes: drying at 55 °C for 12-24 h, then raising the temperature to 400-600 °C at a rate of 2-20 °C / min and holding for 4-6 h.

[0010] Furthermore, the concentration of the citric acid solution is 0.1 M to 1 M.

[0011] In the above-mentioned method for preparing a butene oligomerization catalyst, the heating and stirring step involves heating and stirring at 40-60 °C for 2-6 h.

[0012] A catalyst for the oligomerization of butene to prepare long-chain olefins was prepared using the method described above.

[0013] The above-mentioned catalyst is used in the preparation of jet fuel segment components by butene oligomerization. The steps for preparing jet fuel segment components include: activating the catalyst after loading it into a fixed-bed reactor; and then feeding butene into the fixed-bed reactor filled with the catalyst to carry out the oligomerization reaction.

[0014] Furthermore, the activation process includes: activation at 400 °C in a N2 atmosphere.

[0015] Furthermore, the reaction temperature of the butene oligomerization reaction is 200~300 °C, the reaction pressure is 3~5 MPa, and the mass hourly space velocity of the butene feed is 0.5~2 h⁻¹. -1 .

[0016] The beneficial effects of this invention are: 1. This invention modulates the surface properties and acidic site characteristics of the HZSM-5 molecular sieve by ion exchange treatment with lithium nitrate solution. Experimental data show that the butene conversion rate of the unmodified Z5 catalyst (Example 2) is 72.04%, while the conversion rate of the 0.1Li-Z5 catalyst (Example 1) treated with 0.1M lithium nitrate increases to 96.49% under the same reaction conditions. This indicates that the introduction of lithium ions effectively enhances the catalyst's activation ability for butene molecules; lithium nitrate modification not only improves the conversion rate but also improves the product distribution. As shown in Example 3, when treated with 0.05M lithium nitrate, the C12-C18 yield reaches 28.47%, significantly higher than the 18.32% of the unmodified catalyst. By fine-tuning the lithium ion concentration, sensitive control of the selectivity of the target jet fuel components can be achieved.

[0017] 2. This invention uses citric acid solution to treat HZSM-5 molecular sieves, utilizing its dealumination or acidity adjustment effects to form a micro-mesoporous structure conducive to macromolecular diffusion. Data from Example 7 shows that the catalyst treated with 0.3M citric acid achieved a butene conversion rate of 88.86%, a C8-C18 yield of 76.91%, and a C12-C18 yield of 27.07%. Compared to commercial HZSM-5 catalysts, this modification method improves the pore connectivity of the molecular sieve, reducing the diffusion resistance of reactants and products, thereby enhancing reaction efficiency. 3. This invention achieves good matching with the modified catalyst by limiting specific reaction temperature, pressure, and space velocity. Comparisons in Examples 1, 14, and 15 show that the conversion and yield of the 0.1Li-Z5 catalyst reach a relatively optimal balance at 250°C. Lowering the temperature (220°C) leads to a decrease in conversion to 89.11%, while excessively high temperatures (280°C) maintain a high conversion, but product selectivity declines. Examples 16 and 17 show that when the mass hourly space velocity is... Its time performance is relatively good. However, its airspeed is too slow. This can lead to secondary fission of the product, causing the C12-C18 yield to decrease to 17.60%; excessively high space velocity ( The conversion rate dropped sharply to 85.25% due to insufficient residence time; precise parameter limits ensured the activity stability of the catalyst during long-term operation.

[0018] 4. This invention realizes the conversion of low-carbon olefins into high-value-added liquid fuels, with a yield of up to 79.63% for the generated C12-C18 components, which are characterized by low aromatics and zero sulfur. This not only effectively alleviates the environmental pressure caused by C4 fraction processing, but also provides a high-quality, green and environmentally friendly fuel production path, which has a practical role in ensuring energy security and promoting the sustainable development of the petrochemical industry. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram showing the changes in conversion rate during continuous operation of 0.1Li-Z5, 0.05Li-Z5, and Z5 catalysts. Detailed Implementation

[0021] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] The technical solution of the present invention will be described below through the following embodiments, and the sources of the relevant raw materials are as follows: Commercial HZSM-5 molecular sieve (SiO2 / Al2O3 ratio 27, produced by Tianjin Nankai University Catalyst Factory); commercial Beta molecular sieve (SiO2 / Al2O3 ratio 25, produced by Tianjin Nankai University Catalyst Factory); commercial MCM-41 molecular sieve (SiO2 / Al2O3 ratio 25, produced by Tianjin Nankai University Catalyst Factory); n-Butene (purity 99.99%, produced by Shandong Yong'an Special Equipment Co., Ltd.)

[0023] Example 1 With the increasing market demand for high-quality fuels and the growing severity of global warming and environmental pollution, butene oligomerization to produce long-chain alkanes has become a promising technology due to its advantages such as enabling the high-value utilization of C4 olefins and producing high-quality, green liquid fuels. This technology not only helps address the shortage crisis of high-quality fuels but also reduces greenhouse gas emissions and environmental pollution, contributing to carbon compliance. In this embodiment, 0.1Li-Z5 is used as a catalyst to illustrate the superior performance of molecular sieve catalysts in the butene oligomerization to long-chain alkanes reaction.

[0024] Preparation of 0.1Li-Z5 catalyst: HZSM-5 was added to a 0.1 M lithium nitrate solution, heated and stirred at 80 °C for 8 h, centrifuged and washed, then dried at 55 °C and calcined at 2 °C / min to 500 °C for 4 h to obtain a 0.1 Li-Z5 catalyst.

[0025] Applications of 0.1Li-Z5 catalyst: The catalyst was loaded using a standard fixed-bed catalyst loading process. 5 g of 0.1Li-Z5 catalyst was loaded into the fixed-bed reactor, activated at 350 °C for 4 h in a N2 atmosphere at a flow rate of 40 mL / min, and then the reaction was initiated. The reaction temperature was 250 °C, the reaction pressure was 4 MPa, the N2 flow rate was 140 mL / min, and the mass hourly space velocity (MSV) of the butene feed was 1 h⁻¹. -1 Every hour, gaseous products were collected for analysis, and liquid products obtained from the reaction were also collected for analysis.

[0026] The main evaluation indicators for butene oligomerization activity include: butene conversion rate, yield of C8-C18 alkane and olefin products, and yield of C12-C18 products.

[0027] The specific calculation formula is as follows: Conversion C4 n represents the butene conversion rate. int n represents the amount of butene entering the reactor. out The amount after the reaction, Selectivity C8-C18 Selectivity represents the selectivity of C8-C18 products. C12-C18 Represents the selectivity of C12-C18 products, n i The component with the number of carbons i in the product is represented by 'i', and 'Yield' represents the product yield.

[0028] Represents the olefins in each component.

[0029] In this embodiment, the butene conversion rate reached 96.49%, the yield of C8-C18 alkanes and olefins reached 79.63%, the yield of C12-C18 reached 23.31%, and the catalyst stability was good.

[0030] Example 2 The difference from Example 1 is that the HZSM-5 catalyst in this example was not treated with lithium nitrate. It was directly calcined at 2 °C / min to 500 °C and held for 4 h to obtain the Z5 catalyst. Under the same reaction conditions, the butene conversion rate in this example reached 72.04%, the C8-C18 yield reached 61.85%, and the C12-C18 yield reached 18.32%. Its catalytic performance is much lower than that of the 0.1Li-Z5 catalyst, indicating that lithium nitrate treatment of ZSM-5 molecular sieves can significantly improve the butene oligomerization conversion rate, the yield of C8-C18 alkanes, and the yield of C12-C18 products.

[0031] Example 3 The difference from Example 1 is that this example uses a 0.05 M lithium nitrate solution to prepare a 0.05 M-Z5 catalyst. Under the same reaction conditions, the butene conversion rate in this example reaches 94.67%, the C8-C18 yield reaches 75.18%, and the C12-C18 yield reaches 28.47%, still exhibiting good catalytic activity and selectivity. Furthermore, the C12-C18 yield is higher than that of the 0.1 Li-Z5 catalyst, but its catalyst stability is lower than that of the 0.1 Li-Z5 catalyst.

[0032] Example 4 The difference from Example 1 is that this example uses a 0.3 M lithium nitrate solution to prepare a 0.3 M-Z5 catalyst. Under the same reaction conditions, the butene conversion rate in this example reaches 93.49%, the C8-C18 yield reaches 73.94%, and the C12-C18 yield reaches 21.51%. Its catalyst activity, selectivity, and stability are all lower than those of 0.1 Li-Z.

[0033] Example 5 The difference from Example 1 is that in this example, HZSM-5 was added to a 0.1 M citric acid solution, heated and stirred at 60°C for 2 h, centrifuged and washed until the pH was neutral, then dried at 55°C and calcined at 500°C at a rate of 2°C / min for 4 h to obtain a 0.1 M-Z5 catalyst. Under the same reaction conditions, the butene conversion rate in this example reached 80.89%, the C8-C18 yield reached 69.01%, and the C12-C18 yield reached 20.15%.

[0034] Example 6 The difference from Example 5 is that in this example, a 0.2 M citric acid solution was used to prepare the 0.2 M-Z5 catalyst. Under the same reaction conditions, the butene conversion rate in this example reached 81.87%, the C8-C18 yield reached 70.07%, and the C12-C18 yield reached 20.51%.

[0035] Example 7 The difference from Example 5 is that in this example, a 0.3 M citric acid solution was used to prepare the 0.3 M-Z5 catalyst. Under the same reaction conditions, the butene conversion rate in this example reached 88.86%, the C8-C18 yield reached 76.91%, and the C12-C18 yield reached 27.07%.

[0036] Example 8 The difference from Example 5 is that in this example, a 0.4 M citric acid solution was used to prepare the 0.4 M-Z5 catalyst. Under the same reaction conditions, the butene conversion rate in this example reached 86.57%, the C8-C18 yield reached 71.29%, and the C12-C18 yield reached 19.28%.

[0037] Example 9 The difference from Example 5 is that in this example, a 0.5 M citric acid solution was used to prepare the 0.5 M-Z5 catalyst. Under the same reaction conditions, the butene conversion rate in this example reached 75.03%, the C8-C18 yield reached 64.86%, and the C12-C18 yield reached 19.51%.

[0038] Example 10 Unlike Example 1, in this example, HZSM-5 molecular sieve and Beta were mixed in a 1:1 ratio, water was added (molecular sieve to water ratio was 1:5), and the mixture was stirred until homogeneous. The mixture was then filtered, dried at 55 °C, and subsequently calcined at 400–600 °C with a heating rate of 2–20 °C / min for 4 h to obtain the HB1-1 catalyst. Under the same reaction conditions, the butene conversion rate in this example reached 70.15%, the C8–C18 yield reached 59.56%, and the C12–C18 yield reached 16.07%.

[0039] Example 11 Unlike Example 10, in this example, HZSM-5 molecular sieve and MCM-41 were mixed in a 1:1 ratio to obtain the HM1-1 catalyst. Under the same reaction conditions, the butene conversion rate in this example reached 70.12%, the C8-C18 yield reached 59.25%, and the C12-C18 yield reached 14.03%.

[0040] Example 12 Unlike Example 10, this example uses Beta molecular sieves, which are directly heated to 500 °C at a rate of 2 °C / min and calcined for 4 h to obtain a Beta catalyst. Under the same reaction conditions, the butene conversion rate in this example reaches 53.00%, the C8-C18 yield reaches 43.00%, and the C12-C18 yield reaches 9.05%.

[0041] Example 13 Unlike Example 10, this example uses MCM-41 molecular sieve, which is directly heated to 500 °C at a rate of 2 °C / min and calcined for 4 h to obtain the MCM-41 catalyst. Under the same reaction conditions, the butene conversion rate in this example reaches 42.49%, the C8-C18 yield reaches 28.96%, and the C12-C18 yield reaches 5.87%.

[0042] Molecular sieve catalysts obtained by different preparation methods, different lithium nitrate treatments, different citric acid treatments, and different molecular sieve mixtures exhibit different butene oligomerization catalytic properties, as shown in Table 1 below: Table 1 Catalytic performance of different molecular sieve catalysts a Reaction conditions: mass hourly space velocity 1.0 h⁻¹ -1 The reaction temperature was 250 °C and the reaction time was 11 h.

[0043] Table 1 compares the effects of different modification methods (lithium nitrate treatment, citric acid treatment, and physical mixing) and different treatment concentrations / ratios on catalytic performance. The data in Table 1 are analyzed below: 1) Comparative analysis of lithium nitrate modified group (Examples 1, 3, 4) and unmodified group (Example 2) The unmodified Z5 catalyst (Example 2) achieved a butene conversion of 72.04% and a C12-C18 yield of 18.32%. After treatment with lithium nitrate, the performance was significantly improved across the board. At a lithium nitrate concentration of 0.1M (Example 1), the conversion reached a peak of 96.49%, and the C8-C18 yield reached a maximum of 79.63%. At a concentration of 0.05M (Example 3), the yield of the target long-chain product, C12-C18, reached a maximum of 28.47%. However, if the concentration was further increased to 0.3M (Example 4), all indicators began to decline (conversion 93.49%, C12-C18 yield 21.51%). This demonstrates that lithium nitrate ion exchange can effectively enhance the catalyst's reactivity and selectivity for long-chain alkanes. Furthermore, this modification has a relatively narrow "optimal concentration window" (0.05M~0.1M), where excessively high concentrations can lead to negative effects.

[0044] 2) Trend analysis of citric acid modified group (Examples 5-9) The catalytic performance increased with increasing citric acid concentration (from 0.1M to 0.3M). The optimal concentration was reached at 0.3M (Example 7), achieving a conversion of 88.86% and a C12-C18 yield of 27.07%. Subsequently, when the concentration was further increased to 0.4M (Example 8) and 0.5M (Example 9), the conversion decreased to 86.57% and 75.03%, respectively, and the yield also declined significantly.

[0045] This demonstrates that citric acid dealumination and pore-expansion modification can also improve catalytic performance (superior to unmodified Z5), and its pore-expansion effect has a non-linear relationship with acid concentration, with 0.3M being the optimal concentration for this modification route. However, the overall conversion rate ceiling (88.86%) is lower than that of the lithium nitrate modification route (96.49%).

[0046] 3) Analysis of physically modified composite groups (Examples 10-11) and pure single molecular sieves (Examples 12 and 13) Beta (Example 12) and MCM-41 (Example 13) alone exhibited extremely low catalytic activity, with conversion rates of only 53% and 42.49%, respectively. When mixed with ZSM-5 (Examples 10-11), the conversion rate stabilized at around 70%, which was higher than that of Beta / MCM-41 alone, but lower than that of unmodified pure ZSM-5 (72.04%).

[0047] This demonstrates that the catalytic activity of single Beta, MCM-41, and physically mixed molecular sieves with different pore structures in butene oligomerization is inferior to that of ZSM-5 molecular sieve and lithium nitrate / citric acid-treated modified ZSM-5 molecular sieve.

[0048] Example 14 Unlike Example 1, the reaction temperature in this example was 220 °C, achieving a butene conversion of 89.11%, a C8-C18 yield of 77.01%, and a C12-C18 yield of 20.29%. Lowering the reaction temperature slightly increased the C8-C18 selectivity, but significantly reduced the butene conversion, thus decreasing both the C8-C18 and C12-C18 yields.

[0049] Example 15 Unlike Example 1, the reaction temperature in this example was 280 °C, achieving a butene conversion of 95.49%, a C8-C18 yield of 75.98%, and a C12-C18 yield of 19.56%. Excessively high reaction temperatures led to a decrease in butene conversion and product selectivity, as well as a decrease in the C8-C18 and C12-C18 yields. Therefore, the optimal reaction temperature for the 0.1Li-Z5 catalyst is 250 °C. Example 16 Unlike Example 1, the mass hourly space velocity (MSV) in this example is 0.5 h⁻¹. -1 The butene conversion reached 96.02%, the C8-C18 yield reached 74.75%, and the C12-C18 yield reached 17.60%. However, excessively slow mass hourly space velocity and prolonged residence time led to rapid catalyst deactivation and secondary fission of the product, resulting in decreased conversion and selectivity.

[0050] Example 17 Unlike Example 1, the mass hourly space velocity (MSV) in this example is 1.5 h⁻¹. -1 The butene conversion reached 85.25%, the C8-C18 yield reached 69.11%, and the C12-C18 yield reached 15.49%. Excessive mass hourly space velocity (MHSV) and shortened residence time led to a significant decrease in butene conversion and product selectivity. Therefore, the optimal MHSV for the 0.1Li-Z5 catalyst is 1 h⁻¹. -1 .

[0051] The 0.1Li-Z5 molecular sieve catalyst exhibits different butene oligomerization catalytic properties under different reaction conditions, as shown in Table 2 below.

[0052] Table 2. Reaction performance of 0.1Li-Z5 catalyst under different reaction temperatures and mass hourly space velocities. Table 2, using the best-performing 0.1Li-Z5 catalyst as a benchmark, explores the effects of two core process parameters: reaction temperature and mass hourly space velocity (WHSV). The analysis of Table 2 is as follows: 1) Sensitivity analysis of reaction temperature Example 1 represents the baseline state at 250°C (conversion 96.49%, C12-C18 yield 23.31%). When the temperature decreased to 220°C (Example 14), the reaction driving force was insufficient, resulting in a significant decrease in butene conversion to 89.11%, and a corresponding decrease in the yield of long-chain products. When the temperature increased to 280°C (Example 15), although the conversion remained at a high level of 95.49%, the high temperature exacerbated side reactions such as cracking, causing the yield of long-chain products (C12-C18) to drop sharply to 19.56%.

[0053] This demonstrates that the butene oligomerization reaction catalyzed by 0.1Li-Z5 catalyst is highly sensitive to temperature, and 250℃ is the optimal temperature point for balancing reaction kinetics (conversion rate) and thermodynamic side reactions (long-chain selectivity).

[0054] 2) Matching analysis of mass hourly space velocity (dwell time) Example 1 represents an airspeed of 1 h. -1 The state. When the airspeed decreases to 0.5 h -1 In Example 16, the reactants remained in the reactor for too long, causing secondary cracking of the already formed long-chain olefins, resulting in a sharp decrease in the C12-C18 yield to 17.60%. Conversely, when the space velocity was increased to 1.5 h⁻¹, the yield decreased. -1 In Example 17, the contact time between the reactants and the catalyst was too short, resulting in an incomplete reaction and a significant drop in conversion rate to 85.25%.

[0055] This demonstrates that mass hourly space velocity (MHV) directly determines product distribution and catalyst efficiency. Too high or too low a velocity will disrupt the ideal chain formation for oligomerization. (1.0 h) -1 It is the optimal mass space velocity for this catalytic system.

[0056] Figure 1 The stability of the catalyst before and after lithium nitrate modification was compared. Figure 1 The data analysis is as follows: After 141 hours of continuous operation, the butene conversion rate of 0.1Li-Z5 decreased by only 22.29%, while that of 0.05Li-Z5 decreased by 24.51%. In contrast, the conversion rate of unmodified Z5 dropped sharply after 11 hours of operation, and decreased by 46.96% after 57 hours. This demonstrates that the lithium nitrate treatment method significantly improves the stability of the catalyst, and 0.1Li-Z5 exhibits good stability.

[0057] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0058] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A method for preparing a catalyst for the oligomerization of butene to prepare long-chain olefins, characterized in that, include: HZSM-5 was added to a lithium nitrate solution for ion exchange, followed by centrifugation, washing, drying, and calcination to obtain a modified HZSM-5 molecular sieve catalyst. Alternatively, HZSM-5 can be added to a citric acid solution, heated and stirred, then centrifuged, washed, dried and calcined to obtain a modified HZSM-5 molecular sieve catalyst.

2. The method for preparing a catalyst for the oligomerization of butene to prepare long-chain olefins according to claim 1, characterized in that, The concentration of the lithium nitrate solution is 0.01 M to 0.5 M.

3. The method for preparing a catalyst for the oligomerization of butene to long-chain olefins according to claim 1, characterized in that, The ion exchange process is as follows: heating and stirring at 60~80 ℃ for 6~8 h.

4. The method for preparing a catalyst for the oligomerization of butene to prepare long-chain olefins according to claim 1, characterized in that, The drying and calcination steps include: drying at 55 °C for 12-24 h, then raising the temperature to 400-600 °C at a rate of 2-20 °C / min and holding for 4-6 h.

5. The method for preparing a catalyst for the oligomerization of butene to prepare long-chain olefins according to claim 1, characterized in that, The concentration of the citric acid solution is 0.1 M to 1 M.

6. The method for preparing a butene oligomerization catalyst according to claim 1, characterized in that, The heating and stirring step involves heating and stirring at 40~60 ℃ for 2~6 h.

7. A catalyst for the oligomerization of butene to prepare long-chain olefins, characterized in that, It is prepared by the method described in any one of claims 1-6.

8. The application of the catalyst according to claim 7 in the preparation of jet fuel components by butene oligomerization, characterized in that, The steps for preparing the jet fuel component include: activating the catalyst after loading it into a fixed-bed reactor; and then feeding butene into the fixed-bed reactor filled with the catalyst to carry out an oligomerization reaction.

9. The application according to claim 8, characterized in that, The activation process includes: activation at 400°C in a N2 atmosphere.

10. The application according to claim 8, characterized in that, The reaction temperature of the butene oligomerization reaction is 200-300℃, the reaction pressure is 3-5 MPa, the mass space velocity of butene feed is 0.5-2 h -1 .

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