An olefin metathesis catalyst for increasing the content of liquid end olefins in pyrolysis oil and application thereof

Abstract

The application discloses an olefin metathesis catalyst for improving the content of liquid end olefins in cracking oil and application, the catalyst is a supported metal oxide catalyst, wherein the catalyst contains 1-20wt% of an active component composed of at least one element of W, Mo and Re or an oxide thereof, 0.1-6wt% of an additive composed of one of P, Ga, K and Ca or an oxide thereof, 80-99wt% of a carrier composed of at least one of SiO2, Al2O3 and TiO2; through the catalyst, the effect of adjusting the carbon number distribution of liquid end olefins in cracking oil can be realized, the cracking oil includes petroleum cracking oil, waste tire cracking oil, waste plastic and waste rubber cracking oil and rectification components or the above components treated by dehydrogenation, the catalyst can significantly improve the yield and selectivity of C5-C 12 end olefins, effectively control the carbon number distribution of products, and improve the economic benefits of cracking oil.

Description

Technical Field

[0001] This application belongs to the field of petrochemical and resource recycling technology, specifically relating to an olefin metathesis catalyst for the high-value conversion of cracked oil and its application. It is particularly suitable for using complex cracked oil obtained from the pyrolysis of waste plastics, waste tires, waste rubber, etc., as raw materials, to selectively increase the production of C5-C through catalytic metathesis reactions. 12 Supported metal oxide catalyst system for liquid terminal olefins. Background Technology

[0002] With the advancement of the "dual carbon" goals, the chemical recycling of polymeric waste such as waste plastics and waste tires has become a research hotspot. Thermal cracking is the mainstream treatment method, but the resulting cracked oil has a complex composition, rich in olefins, aromatics, and oxygen-containing compounds, while high-value-added C5-C... 12 The content of terminal olefins is low.

[0003] Terminal olefins are olefins with double bonds located at the ends of molecular chains. They are chemically reactive and have a wide range of applications in chemical production. For example, in the field of polymer synthesis, terminal olefins can be used as polyolefin comonomers to copolymerize with ethylene and other materials to prepare high-performance polymers such as high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), and polyolefin elastomers (POE). Terminal olefins can also be used to produce surfactants and detergents as well as to prepare high-performance lubricants.

[0004] Currently, various industrial processes have been developed to produce terminal olefins, including ethylene oligomerization, Fischer-Tropsch synthesis, and petroleum cracking. Tires, plastics, and rubber are all petrochemical products, and their cracking can produce cracked oil. Cracked oil is a complex mixture, mainly composed of 10-40% alkanes, 10-40% olefins, 10-30% cycloalkanes, and 10-70% aromatics. To increase the yield of terminal olefins in cracked oil, industry mainly employs fractionation, solvent extraction, or chemical synthesis methods (such as alkane dehydrogenation). However, these methods often rely on energy-intensive physical separation or harsh chemical reaction conditions, leading to low efficiency, catalyst deactivation, and numerous byproducts, making it difficult to meet the growing demands for refined production.

[0005] Against this backdrop, olefin metathesis, as a highly atom-economical catalytic conversion pathway with precisely controllable carbon chain structure, can theoretically convert the abundant internal olefins in cracked oil into high-value terminal olefins through the cross-metathesis of internal olefins and ethylene. However, existing olefin metathesis technologies are almost entirely limited to gaseous olefins (such as propylene and butene) or high-purity model compounds (such as 2-pentene and 2-octene). For example, W / SiO2 or Re2O7 / Al2O3 catalysts have been successfully used industrially to achieve propylene self-metathesis or ethylene / butene cross-metathesis to propylene, but there is still no mature technology to systematically apply metathesis reactions to liquid cracked oil derived from real waste materials such as waste plastics and waste tires.

[0006] These types of cracked oils present three major challenges: (1) their composition is extremely complex, containing a large amount of aromatics, sulfur and nitrogen impurities, and gums; (2) their internal olefins have a wide carbon number distribution (C6-C6). 20 + ), and often with >C 12 (3) Coexistence of heavy components; poor thermal stability, prone to coking at high temperatures. Existing heterogeneous catalysts (such as MoO2) x When faced with such complex systems, Al2O3 and WO3 / SiO3 often rapidly deactivate and their selectivity drops sharply, making it impossible to achieve stable and efficient end-olefin production.

[0007] Besides heterogeneous catalysts (such as Mo, W, and Re oxides), ruthenium carbene complexes are also widely used as homogeneous catalysts for olefin metathesis reactions in existing technologies. Although ruthenium carbene complexes exhibit excellent catalytic performance in certain applications, their application in liquid olefins, especially complex cracked oils, faces numerous challenges, including high cost, extreme sensitivity to impurities, difficulty in recovery and regeneration, and easy decomposition in high-temperature liquid-phase environments. Therefore, they are completely unsuitable for the continuous treatment of industrial-grade waste cracked oils.

[0008] Therefore, there is an urgent need to develop a novel metathesis catalyst to extend olefin metathesis technology from pure gaseous olefin systems to complex liquid pyrolysis oil systems such as waste plastics and waste tires, while maintaining high activity and stability in complex pyrolysis oil systems and significantly improving C5-C content. 12 The selectivity and yield of terminal olefins enable the efficient and high-value conversion of waste polymer resources.

[0009] This application addresses this technological gap by proposing, for the first time, a supported metal oxide metathesis catalyst specifically tailored for complex cracked oils. Through the synergistic design of the active components (W / Mo / Re), promoters (P / Ga / K / Ca), and support (SiO2 / Al2O3 / TiO2), it achieves highly selective and stable C5-C production enhancement in real waste cracked oils. 12Terminal olefins have significant prospects for industrial applications. Summary of the Invention

[0010] According to one aspect of this application, a method for increasing C5-C content in cracked oil is provided. 12 An olefin metathesis catalyst with a liquid-terminated olefin content; the catalyst is a supported metal oxide catalyst, comprising, by weight percentage: 1~20wt% of an active component, wherein the active component is at least one element selected from W, Mo and Re or an oxide thereof; 0.1~6wt% of additives, wherein the additives are one of P, Ga, K and Ca or oxides thereof; The support comprises 80-99 wt% of SiO2, Al2O3 and TiO2.

[0011] In this application, liquid-terminated olefins refer to olefins with 5 to 12 carbon atoms in their molecules, abbreviated as C5-C. 12 Terminal olefins.

[0012] Optionally, the content of at least one element of W, Mo and Re or its oxide in the active component is 3 to 10 wt%.

[0013] Optionally, the content of the auxiliary agent P, Ga, K or Ca element is 0.1~wt3%.

[0014] Optionally, the support is at least one of SiO2, Al2O3 and TiO2, with a content of 90~97wt%.

[0015] The catalyst is prepared by the following method: S1. Mix a certain amount of soluble salts of Mo, W and / or Re with water to obtain an aqueous solution of Mo, Wo and / or Re; S2. Mix a certain amount of soluble salts of P, Ga, K or Ca with water to obtain an aqueous solution of P, Ga, K or Ca. S3. Add a certain amount of support particles to an aqueous solution of Mo, Wo and / or Re, impregnate for 3-6 hours, and then perform rotary evaporation, drying and calcination in sequence to obtain an intermediate catalyst with supported active components. S4. The intermediate catalyst is added to the aqueous solution of P, Ga, K or Ca and impregnated for 4-8 hours, followed by rotary evaporation, drying and calcination to obtain the supported metal oxide catalyst.

[0016] Optionally, the soluble salt of Mo in step S1 is selected from at least one of ammonium heptamolybdate, ammonium molybdate, and molybdenum nitrate; The soluble salt of W is ammonium metatungstate, and the soluble salt of Re is ammonium perrhenate; Preferably, the soluble salt of Mo is ammonium molybdate.

[0017] Optionally, the auxiliary agent source in step S2 is a P source, a Ga source, a K source, or a Ca source; The soluble salt of P is selected from at least one of phosphoric acid, ammonium phosphate, ammonium dihydrogen phosphate, and ammonium metaphosphate. The soluble salt of Ga is selected from at least one of gallium nitrate, gallium sulfate, and gallium chloride; The soluble salt of K is selected from at least one of potassium nitrate, potassium sulfate, and potassium chloride; The soluble salt of Ca is selected from at least one of calcium nitrate, calcium acetate, and calcium chloride; Preferably, the soluble salt of P is ammonium dihydrogen phosphate; Preferably, the soluble salt of Ga is gallium nitrate; Preferably, the soluble salt of K is potassium nitrate; Preferably, the soluble salt of Ca is calcium nitrate.

[0018] Optionally, the rotary evaporation temperature in step S3 is 60-80℃, the drying temperature is 60-100℃, the drying time is 6-12h, the calcination temperature is 500-800℃, and the calcination time is 2-8h.

[0019] Optionally, the rotary evaporation temperature in step S4 is 50-80℃, the drying temperature is 80-120℃, the drying time is 6-12h, the calcination temperature is 600-900℃, and the calcination time is 4-8h.

[0020] According to another aspect of this application, there is a method for increasing the C5-C content in cracked oil. 12 A method for determining the content of olefins in the liquid phase, using an olefin metathesis catalyst as described above, at a reaction temperature of 100–500 °C, a reaction pressure of 0–3 MPa, and an ethylene mass hourly space velocity of 0.1–10 h⁻¹. -1 Under certain conditions, ethylene is subjected to a metathesis reaction with cracked oil.

[0021] Optionally, the cracked oil includes petroleum cracked oil, waste tire cracked oil, waste plastic and waste rubber cracked oil, and distillation components or the above components that have undergone dehydrogenation treatment.

[0022] The beneficial effects that this application can produce include: 1) The olefin metathesis catalyst and its preparation method provided in this application use P, Ga, K or Ca as promoters, which work synergistically with the active components Mo, Re and / or W in the liquid olefin metathesis reaction system in cracked oil, which significantly improves the activity and selectivity of the catalyst and effectively promotes the directional conversion of internal olefins to terminal olefins.

[0023] 2) The olefin metathesis catalyst provided in this application can precisely adjust the carbon number distribution of liquid-terminal olefins in cracked oil, significantly increasing the C5-C ratio. 12 The yield of terminal olefins is increased by 25% to 60% and the selectivity is increased by 50% to 70%, thereby significantly improving the resource utilization value and economic added value of cracked oil.

[0024] 3) This application adopts a stepwise impregnation-calcination process to sequentially load active components and additives, which is not only simple to operate and easy to scale up industrially, but also conducive to optimizing the spatial distribution and interaction of active metals and additives on the surface of the support, thereby improving the overall performance and stability of the catalyst.

[0025] 4) This application adopts a conventional step-by-step impregnation method, which is easy to scale up for industrial production. Detailed Implementation

[0026] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0027] The specific embodiments of this application are described in detail below. The specific embodiments described herein are for illustration and explanation only, and are not intended to limit this application.

[0028] The analysis method in the embodiments of this application is as follows: Qualitative analysis of liquid components was performed using a gas chromatograph-quadrupole time-of-flight high-resolution mass spectrometer.

[0029] Quantitative analysis of liquid components using gas chromatography.

[0030] In the embodiments of this application, the total olefin content α, C5-C 12 Total terminal olefin content β, internal olefin conversion ω, and C5-C 12 Terminal olefin selectivity The calculation is as follows:

[0031] Where α represents the percentage of total olefins in the liquid hydrocarbons, α i This represents the percentage of olefins with carbon number i in the liquid hydrocarbons.

[0032]

[0033] in, Indicates the C5-C content of liquid hydrocarbons before and after the reaction. 12 Percentage of total terminal olefins This represents the percentage of terminal olefins with carbon number j in the liquid olefins before and after the reaction.

[0034]

[0035] Where ω represents C5-C 12 Terminal olefin yield, m0 represents the amount of cracked oil continuously fed into the fixed bed, and m1 represents the mass of liquid product collected after a period of time.

[0036]

[0037] in, Indicates C5-C 12 Terminal olefin selectivity, where m0 represents the amount of cracked oil continuously fed into the fixed bed, and m1 represents the mass of the liquid product collected after a period of time.

[0038] Example 1 Catalyst preparation: 3% MoO x -0.5%K / Al2O3 (i.e., containing 3 wt% MoO3, 0.5 wt% K2O, and the balance being Al2O3).

[0039] S1: Dissolve 0.5517g of ammonium molybdate in 100mL of deionized water at 80℃ to obtain an ammonium molybdate solution of 0.0045mol / L.

[0040] S2: Dissolve 0.1293g of potassium nitrate in 100mL of deionized water to obtain a potassium nitrate solution of 0.013mol / L.

[0041] S3: Add 10g of Al2O3 particles to the solution from step S1, stir at room temperature for 4 hours, then dry under vacuum at 60℃, dry in a vacuum oven at 80℃ for 12 hours, and then calcine in a muffle furnace at 600℃ for 4 hours to obtain 3% MoO. x / Al2O3.

[0042] S4: Add the catalyst precursor prepared in step S3 to the solution from step S2, stir at room temperature for 6 hours, then dry under vacuum at 50°C, dry in a vacuum oven at 80°C for 6 hours, and then calcine in a muffle furnace at 800°C for 4 hours to obtain 3% MoO. x -0.5%K / Al2O3.

[0043] Using the above catalyst, waste plastic pyrolysis oil (olefin content 40%, of which C5-C) was processed in a fixed-bed reactor. 12 Terminal olefins account for 40%, with the remainder being internal olefins and >C. 12 The olefin metathesis reaction of olefins and ethylene was carried out under the following conditions: reaction pressure 1.5 MPa, reaction temperature 300 °C, and ethylene mass hourly space velocity 1.5 h⁻¹. -1 The feed rate of waste plastic pyrolysis oil was 1 mL / min. After 2 hours, the liquid product was collected and analyzed by gas chromatography. The analysis results are shown in Table 1.

[0044] Example 2 Catalyst preparation: 5% MoO x -1.5%K / Al2O3 S1: Dissolve 0.9195g of ammonium molybdate in 100mL of deionized water at 80℃ to obtain an ammonium molybdate solution of 0.0074mol / L.

[0045] S2: Dissolve 0.3878g of potassium nitrate in 100mL of deionized water to obtain a potassium nitrate solution of 0.038mol / L.

[0046] S3: Add 10g of Al2O3 particles to the solution from step S1, stir at room temperature for 4 hours, then dry under vacuum at 60℃, dry in a vacuum oven at 80℃ for 12 hours, and then calcine in a muffle furnace at 600℃ for 4 hours to obtain 5% MoO. x / Al2O3.

[0047] S4: Add the catalyst precursor prepared in step S3 to the solution from step S2, stir at room temperature for 6 hours, then dry under vacuum at 50°C, dry in a vacuum oven at 80°C for 6 hours, and then calcine in a muffle furnace at 800°C for 4 hours to obtain 5% MoO. x -1.5%K / Al2O3.

[0048] Using the above catalyst, waste plastic pyrolysis oil (olefin content 40%, of which C5-C) was processed in a fixed-bed reactor. 12 Terminal olefins account for 40%, with the remainder being internal olefins and >C. 12 The olefin metathesis reaction of olefins and ethylene was carried out under the following conditions: reaction pressure 1.5 MPa, reaction temperature 300 °C, and ethylene mass hourly space velocity 1.5 h⁻¹. -1 The feed rate of waste plastic pyrolysis oil was 1 mL / min. After 2 hours, the liquid product was collected and analyzed by gas chromatography. The analysis results are shown in Table 1.

[0049] Example 3 Catalyst preparation: 9% MoO x -1.5%Ca / Al2O3 S1: Dissolve 1.655g of ammonium molybdate in 100mL of deionized water at 80℃ to obtain a 0.0134mol / L ammonium molybdate solution.

[0050] S2: Dissolve 0.8837g of calcium nitrate tetrahydrate in 100mL of deionized water to obtain a 0.037mol / L calcium nitrate solution.

[0051] S3: Add 10g of Al2O3 particles to the solution from step S1, stir at room temperature for 4 hours, then dry under vacuum at 60℃, dry in a vacuum oven at 80℃ for 12 hours, and then calcine in a muffle furnace at 600℃ for 4 hours to obtain 9% MoO2. x / Al2O3.

[0052] S4: Add the catalyst precursor prepared in step S3 to the solution from step S2, stir at room temperature for 6 hours, then dry under vacuum at 50°C, dry in a vacuum oven at 80°C for 6 hours, and then calcine in a muffle furnace at 800°C for 4 hours to obtain 9% MoO. x -1.5%Ca / Al2O3.

[0053] Using the above catalyst, waste plastic pyrolysis oil (olefin content 40%, of which C5-C) was processed in a fixed-bed reactor. 12 Terminal olefins account for 40%, with the remainder being internal olefins and >C. 12 The olefin metathesis reaction of olefins and ethylene was carried out under the following conditions: reaction pressure 1.5 MPa, reaction temperature 300 °C, and ethylene mass hourly space velocity 1.5 h⁻¹. -1 The feed rate of waste plastic pyrolysis oil was 1 mL / min. After 2 hours, the liquid product was collected and analyzed by gas chromatography. The analysis results are shown in Table 1.

[0054] Example 4 Catalyst preparation: 5% MoO x -0.5%Ca / Al2O3 S1: Dissolve 0.9195g of ammonium molybdate in 100mL of deionized water at 80℃ to obtain an ammonium molybdate solution of 0.0074mol / L.

[0055] S2: Dissolve 0.2945g of calcium nitrate tetrahydrate in 100mL of deionized water to obtain a 0.012mol / L calcium nitrate solution.

[0056] S3: Add 10g of Al2O3 particles to the solution from step S1, stir at room temperature for 4 hours, then dry under vacuum at 60℃, dry in a vacuum oven at 80℃ for 12 hours, and then calcine in a muffle furnace at 600℃ for 4 hours to obtain 5% MoO. x / Al2O3.

[0057] S4: Add the catalyst precursor prepared in step S3 to the solution from step S2, stir at room temperature for 6 hours, then dry under vacuum at 50°C, dry in a vacuum oven at 80°C for 6 hours, and then calcine in a muffle furnace at 800°C for 4 hours to obtain 5% MoO. x -0.5%Ca / Al2O3.

[0058] Using the above catalyst, waste plastic pyrolysis oil (olefin content 40%, of which C5-C) was processed in a fixed-bed reactor. 12 Terminal olefins account for 40%, with the remainder being internal olefins and >C. 12 The olefin metathesis reaction of olefins and ethylene was carried out under the following conditions: reaction pressure 1.5 MPa, reaction temperature 300 °C, and ethylene mass hourly space velocity 1.5 h⁻¹. -1 The feed rate of waste plastic pyrolysis oil was 1 mL / min. After 2 hours, the liquid product was collected and analyzed by gas chromatography. The analysis results are shown in Table 1.

[0059] Example 5 Catalyst preparation: 3% WO3 - 0.5% P / SiO2 S1: Dissolve 0.4020 g of ammonium metatungstate in 100 mL of deionized water to obtain a 0.0014 mol / L ammonium metatungstate solution.

[0060] S2: Dissolve 0.1857 g of ammonium dihydrogen phosphate in 100 mL of deionized water to obtain a 0.016 mol / L ammonium dihydrogen phosphate solution.

[0061] S3: Add 10g of SiO2 particles to the solution in step S1, stir at room temperature for 4h, then vacuum evaporate to dryness at 60℃, dry in a vacuum oven at 80℃ for 12h, then place in a muffle furnace and calcine at 600℃ for 4h to obtain 3%WO3 / SiO2.

[0062] S4: Add the catalyst precursor prepared in step S3 to the solution in step S2, stir at room temperature for 6 hours, then dry under vacuum at 50°C, dry in a vacuum oven at 80°C for 6 hours, and then calcine in a muffle furnace at 800°C for 4 hours to obtain 3%WO3-0.5%P / SiO2.

[0063] Using the above catalyst, waste tire pyrolysis oil (olefin content 25%, of which C5-C4) was processed in a fixed-bed reactor. 12 Terminal olefins account for 12%, with the remainder being internal olefins and >C. 12 The olefin metathesis reaction of olefins and ethylene was carried out under the following conditions: reaction pressure 2 MPa, reaction temperature 400 °C, and ethylene mass hourly space velocity 3 h⁻¹. -1 The feed rate of waste tire pyrolysis oil was 1 mL / min. After 2 hours, the liquid product was collected and analyzed by gas chromatography. The analysis results are shown in Table 2.

[0064] Example 6 Catalyst preparation: 5% WO3-1.5% P / SiO2 S1: Dissolve 0.6700g of ammonium metatungstate in 100mL of deionized water to obtain a 0.0022mol / L ammonium metatungstate solution.

[0065] S2: Dissolve 0.5571g of ammonium dihydrogen phosphate in 100mL of deionized water to obtain a 0.048mol / L ammonium dihydrogen phosphate solution.

[0066] S3: Add 10g of SiO2 particles to the solution in step S1, stir at room temperature for 4h, then vacuum evaporate to dryness at 60℃, dry in a vacuum oven at 80℃ for 12h, then place in a muffle furnace and calcine at 600℃ for 4h to obtain 5%WO3 / SiO2.

[0067] S4: Add the catalyst precursor prepared in step S3 to the solution in step S2, stir at room temperature for 6 hours, then dry under vacuum at 50°C, dry in a vacuum oven at 80°C for 6 hours, and then calcine in a muffle furnace at 800°C for 4 hours to obtain 5%WO3-1.5%P / SiO2.

[0068] Using the above catalyst, waste tire pyrolysis oil (olefin content 25%, of which C5-C4) was processed in a fixed-bed reactor. 12 Terminal olefins account for 12%, with the remainder being internal olefins and >C. 12 The olefin metathesis reaction of olefins and ethylene was carried out under the following conditions: reaction pressure 2 MPa, reaction temperature 400 °C, and ethylene mass hourly space velocity 3 h⁻¹. -1 The feed rate of waste tire pyrolysis oil was 1 mL / min. After 2 hours, the liquid product was collected and analyzed by gas chromatography. The analysis results are shown in Table 2.

[0069] Example 7 Catalyst preparation: 9% WO3-1.5% K / SiO2 S1: Dissolve 1.2059 g of ammonium metatungstate in 100 mL of deionized water to obtain a 0.0040 mol / L ammonium metatungstate solution.

[0070] S2: Dissolve 0.3879 g of potassium nitrate in 100 mL of deionized water to obtain a 0.039 mol / L potassium nitrate solution.

[0071] S3: Add 10g of SiO2 particles to the solution in step S1, stir at room temperature for 4h, then vacuum evaporate to dryness at 60℃, dry in a vacuum oven at 80℃ for 12h, then place in a muffle furnace and calcine at 600℃ for 4h to obtain 9%WO3 / SiO2.

[0072] S4: Add the catalyst precursor prepared in step S3 to the solution in step S2, stir at room temperature for 6 hours, then dry under vacuum at 50°C, dry in a vacuum oven at 80°C for 6 hours, and then calcine in a muffle furnace at 800°C for 4 hours to obtain 9%WO3-1.5%K / SiO2.

[0073] Using the above catalyst, waste tire pyrolysis oil (olefin content 25%, of which C5-C4) was processed in a fixed-bed reactor. 12 Terminal olefins account for 12%, with the remainder being internal olefins and >C. 12 The olefin metathesis reaction of olefins and ethylene was carried out under the following conditions: reaction pressure 2 MPa, reaction temperature 400 °C, and ethylene mass hourly space velocity 3 h⁻¹. -1 The feed rate of waste tire pyrolysis oil was 1 mL / min. After 2 hours, the liquid product was collected and analyzed by gas chromatography. The analysis results are shown in Table 2.

[0074] Example 8 Catalyst preparation: 5% WO3-0.5% K / SiO2 S1: Dissolve 0.6700g of ammonium metatungstate in 100mL of deionized water to obtain a 0.0023mol / L ammonium metatungstate solution.

[0075] S2: Dissolve 0.1293g of potassium nitrate in 100mL of deionized water to obtain a potassium nitrate solution of 0.013mol / L.

[0076] S3: Add 10g of SiO2 particles to the solution in step S1, stir at room temperature for 4h, then vacuum evaporate to dryness at 60℃, dry in a vacuum oven at 80℃ for 12h, then place in a muffle furnace and calcine at 600℃ for 4h to obtain 5%WO3 / SiO2.

[0077] S4: Add the catalyst precursor prepared in step S3 to the solution in step S2, stir at room temperature for 6 hours, then dry under vacuum at 50°C, dry in a vacuum oven at 80°C for 6 hours, and then place in a muffle furnace and calcine at 800°C for 4 hours to obtain 5%WO3-0.5%K / SiO2.

[0078] Using the above catalyst, waste tire pyrolysis oil (olefin content 25%, of which C5-C4) was processed in a fixed-bed reactor. 12 Terminal olefins account for 12%, with the remainder being internal olefins and >C. 12 The olefin metathesis reaction of olefins and ethylene was carried out under the following conditions: reaction pressure 2 MPa, reaction temperature 400 °C, and ethylene mass hourly space velocity 3 h⁻¹. -1 The feed rate of waste tire pyrolysis oil was 1 mL / min. After 2 hours, the liquid product was collected and analyzed by gas chromatography. The analysis results are shown in Table 2.

[0079] Example 9 Catalyst preparation: 3% Re₂O₇-0.5% P / TiO₂ S1: Dissolve 0.4322 g of ammonium perrhenate in 100 mL of deionized water to obtain a 0.016 mol / L ammonium perrhenate solution.

[0080] S2: Dissolve 0.1857 g of ammonium dihydrogen phosphate in 100 mL of deionized water to obtain a 0.016 mol / L ammonium dihydrogen phosphate solution.

[0081] S3: Add 10g of TiO2 particles to the solution in step S1, stir at room temperature for 4h, then vacuum evaporate to dryness at 60℃, dry in a vacuum oven at 80℃ for 12h, then place in a muffle furnace and calcine at 600℃ for 4h to obtain 3% Re2O7 / TiO2.

[0082] S4: Add the catalyst precursor prepared in step S3 to the solution in step S2, stir at room temperature for 6 hours, then dry under vacuum at 50°C, dry in a vacuum oven at 80°C for 6 hours, and then calcine in a muffle furnace at 800°C for 4 hours to obtain 3%Re2O7-0.5%P / TiO2.

[0083] Using the above catalyst, waste rubber pyrolysis oil (olefin content 33%, of which C5-C) was processed in a fixed-bed reactor. 12 Terminal olefins accounted for 42%, with the remainder being internal olefins and >C. 12 The olefin metathesis reaction of olefins and ethylene was carried out under the following conditions: reaction pressure 2.5 MPa, reaction temperature 450 °C, and ethylene mass hourly space velocity 7 h⁻¹. -1 The feed rate of waste rubber pyrolysis oil was 1 mL / min. After 2 hours, the liquid product was collected and analyzed by gas chromatography. The analysis results are shown in Table 3.

[0084] Example 10 Catalyst preparation: 5% Re₂O₇ - 1.5% P / TiO₂ S1: Dissolve 0.7203g of ammonium perrhenate in 100mL of deionized water to obtain a 0.027mol / L ammonium perrhenate solution.

[0085] S2: Dissolve 0.5571g of ammonium dihydrogen phosphate in 100mL of deionized water to obtain a 0.048mol / L ammonium dihydrogen phosphate solution.

[0086] S3: Add 10g of TiO2 particles to the solution in step S1, stir at room temperature for 4h, then vacuum evaporate to dryness at 60℃, dry in a vacuum oven at 80℃ for 12h, then place in a muffle furnace and calcine at 600℃ for 4h to obtain 5% Re2O7 / TiO2.

[0087] S4: Add the catalyst precursor prepared in step S3 to the solution in step S2, stir at room temperature for 6 hours, then dry under vacuum at 50°C, dry in a vacuum oven at 80°C for 6 hours, and then calcine in a muffle furnace at 800°C for 4 hours to obtain 5%Re2O7-1.5%P / TiO2.

[0088] Using the above catalyst, waste rubber pyrolysis oil (olefin content 33%, of which C5-C) was processed in a fixed-bed reactor. 12 Terminal olefins accounted for 42%, with the remainder being internal olefins and >C. 12 The olefin metathesis reaction of olefins and ethylene was carried out under the following conditions: reaction pressure 2.5 MPa, reaction temperature 450 °C, and ethylene mass hourly space velocity 7 h⁻¹. -1 The feed rate of waste rubber pyrolysis oil was 1 mL / min. After 2 hours, the liquid product was collected and analyzed by gas chromatography. The analysis results are shown in Table 3.

[0089] Example 11 Catalyst preparation: 9% Re₂O₇ - 1.5% Ga / TiO₂ S1: Dissolve 1.2965g of ammonium perrhenate in 100mL of deionized water to obtain a 0.048mol / L ammonium perrhenate solution.

[0090] S2: Dissolve 0.3308g of gallium nitrate in 100mL of deionized water to obtain a gallium nitrate solution of 0.022mol / L.

[0091] S3: Add 10g of TiO2 particles to the solution in step S1, stir at room temperature for 4h, then vacuum evaporate to dryness at 60℃, dry in a vacuum oven at 80℃ for 12h, then place in a muffle furnace and calcine at 600℃ for 4h to obtain 9% Re2O7 / TiO2.

[0092] S4: Add the catalyst precursor prepared in step S3 to the solution in step S2, stir at room temperature for 6 h, then dry under vacuum at 50 °C, dry in a vacuum oven at 80 °C for 6 h, then place in a muffle furnace and calcine at 800 °C for 4 h to obtain 9%Re2O7-1.5%Ga / TiO2.

[0093] Using the above catalyst, waste rubber pyrolysis oil (olefin content 33%, of which C5-C) was processed in a fixed-bed reactor. 12 Terminal olefins accounted for 42%, with the remainder being internal olefins and >C. 12 The olefin metathesis reaction of olefins and ethylene was carried out under the following conditions: reaction pressure 2.5 MPa, reaction temperature 450 °C, and ethylene mass hourly space velocity 7 h⁻¹. -1 The feed rate of waste rubber pyrolysis oil was 1 mL / min. After 2 hours, the liquid product was collected and analyzed by gas chromatography. The analysis results are shown in Table 3.

[0094] Example 12 Catalyst preparation: 5% Re₂O₇ - 0.5% Ga / TiO₂ S1: Dissolve 0.7203g of ammonium perrhenate in 100mL of deionized water to obtain a 0.027mol / L ammonium perrhenate solution.

[0095] S2: Dissolve 0.1103 g of gallium nitrate in 100 mL of deionized water to obtain a gallium nitrate solution of 0.007 mol / L.

[0096] S3: Add 10g of TiO2 particles to the solution in step S1, stir at room temperature for 4h, then vacuum evaporate to dryness at 60℃, dry in a vacuum oven at 80℃ for 12h, then place in a muffle furnace and calcine at 600℃ for 4h to obtain 5% Re2O7 / TiO2.

[0097] S4: Add the catalyst precursor prepared in step S3 to the solution in step S2, stir at room temperature for 6 h, then dry under vacuum at 50 °C, dry in a vacuum oven at 80 °C for 6 h, then place in a muffle furnace and calcine at 800 °C for 4 h to obtain 5%Re2O7-0.5%Ga / TiO2.

[0098] Using the above catalyst, waste rubber pyrolysis oil (olefin content 33%, of which C5-C) was processed in a fixed-bed reactor. 12 Terminal olefins accounted for 42%, with the remainder being internal olefins and >C. 12 The olefin metathesis reaction of olefins and ethylene was carried out under the following conditions: reaction pressure 2.5 MPa, reaction temperature 450 °C, and ethylene mass hourly space velocity 7 h⁻¹. -1 The feed rate of waste rubber pyrolysis oil was 1 mL / min. After 2 hours, the liquid product was collected and analyzed by gas chromatography. The analysis results are shown in Table 3.

[0099] Comparative Example 1 Catalyst preparation: 5% MoO x / Al2O3 S1: Dissolve 0.9195g of ammonium molybdate in 100mL of deionized water at 80℃ to obtain an ammonium molybdate solution of 0.0074mol / L.

[0100] S2: Add 10g of Al2O3 particles to the solution from step S1, stir at room temperature for 4 hours, then dry under vacuum at 60℃, dry in a vacuum oven at 80℃ for 12 hours, and then calcine in a muffle furnace at 600℃ for 4 hours to obtain 5% MoO. x / Al2O3.

[0101] Using the above catalyst, waste plastic pyrolysis oil (olefin content 40%, of which C5-C) was processed in a fixed-bed reactor. 12 Terminal olefins account for 40%, with the remainder being internal olefins and >C. 12 The olefin metathesis reaction of olefins and ethylene was carried out under the following conditions: reaction pressure 1.5 MPa, reaction temperature 300 °C, and ethylene mass hourly space velocity 1.5 h⁻¹. -1 The feed rate of waste plastic pyrolysis oil was 1 mL / min. After 2 hours, the liquid product was collected and analyzed by gas chromatography. The analysis results are shown in Table 1.

[0102] Comparative Example 2 Catalyst preparation: 5% WO3 / SiO2 S1: Dissolve 0.6700g of ammonium metatungstate in 100mL of deionized water to obtain a 0.0023mol / L ammonium metatungstate solution.

[0103] S2: Add 10g of SiO2 particles to the solution in step S1, stir at room temperature for 4h, then vacuum evaporate to dryness at 60℃, dry in a vacuum oven at 80℃ for 12h, then place in a muffle furnace and calcine at 600℃ for 4h to obtain 5%WO3 / SiO2.

[0104] Using the above catalyst, waste tire pyrolysis oil (olefin content 25%, of which C5-C4) was processed in a fixed-bed reactor. 12 Terminal olefins account for 12%, with the remainder being internal olefins and >C. 12 The olefin metathesis reaction of olefins and ethylene was carried out under the following conditions: reaction pressure 2 MPa, reaction temperature 400 °C, and ethylene mass hourly space velocity 3 h⁻¹. -1 The feed rate of waste tire pyrolysis oil was 1 mL / min. After 2 hours, the liquid product was collected and analyzed by gas chromatography. The analysis results are shown in Table 2.

[0105] Comparative Example 3 Catalyst preparation: 5% Re2O7 / TiO2 S1: Dissolve 0.7203g of ammonium perrhenate in 100mL of deionized water to obtain a 0.027mol / L ammonium perrhenate solution.

[0106] S2: Add 10g of TiO2 particles to the solution in step S1, stir at room temperature for 4h, then vacuum evaporate to dryness at 60℃, dry in a vacuum oven at 80℃ for 12h, then place in a muffle furnace and calcine at 600℃ for 4h to obtain 5% Re2O7 / TiO2.

[0107] Using the above catalyst, waste rubber pyrolysis oil (olefin content 33%, of which C5-C) was processed in a fixed-bed reactor. 12Terminal olefins accounted for 42%, with the remainder being internal olefins and >C. 12 The olefin metathesis reaction of olefins and ethylene was carried out under the following conditions: reaction pressure 2.5 MPa, reaction temperature 450 °C, and ethylene mass hourly space velocity 7 h⁻¹. -1 The feed rate of waste rubber pyrolysis oil was 1 mL / min. After 2 hours, the liquid product was collected and analyzed by gas chromatography. The analysis results are shown in Table 3.

[0108] Comparative Example 4 Catalyst preparation: 0.5%Mo-0.5%K / Al2O3 S1: Dissolve 0.092g of ammonium molybdate in 100mL of deionized water at 80℃, and stir until completely dissolved; S2: Dissolve 0.129g of potassium nitrate in 100mL of deionized water and stir until completely dissolved; S3: Add 10g of Al2O3 particles to the solution in step S1, stir at room temperature for 4h, then vacuum evaporate to dryness at 60℃, dry in a vacuum oven at 80℃ for 12h, then place in a muffle furnace and calcine at 600℃ for 4h to obtain 0.5%Mo / Al2O3.

[0109] S4: Add the catalyst precursor prepared in step S3 to the solution in step S2, stir at room temperature for 6 hours, then dry under vacuum at 50°C, dry in a vacuum oven at 80°C for 6 hours, and then calcine in a muffle furnace at 800°C for 4 hours to obtain 0.5%Mo-0.5%K / Al2O3.

[0110] Using the above catalyst, in a fixed-bed reactor, waste plastic pyrolysis oil (olefin content 40%, of which C5-C4) is produced. 12 Terminal olefins account for 40%, with the remainder being internal olefins and >C. 12 The reaction was carried out using olefins and ethylene as raw materials under the following conditions: 300℃, 1.5 MPa, and ethylene mass hourly space velocity (MHV) of 1.5 h⁻¹. -1 The feed rate of the cracked oil was 1 mL / min. Samples were taken for analysis after 2 hours of reaction. C5-C 12 The yield of terminal olefins was 12.3%, and the selectivity was 58.1%.

[0111] Comparative Example 5 Catalyst preparation: 25%Mo–0.5%K / Al2O3 S1: Weigh 4.598 g of ammonium molybdate and dissolve it in 100 mL of deionized water at 80℃; S2: Weigh 0.129 g of potassium nitrate and dissolve it in 100 mL of deionized water; S3: Add 10.0 g of Al2O3 particles to the S1 solution and stir at room temperature for 4 h; evaporate at 60℃ and dry at 80℃ for 12 h; calcine at 600℃ for 4 h to obtain 25%Mo / Al2O3; S4: Add the product of S3 to the solution of S2 and impregnate at room temperature for 6 h; evaporate at 50 °C and dry at 80 °C for 6 h; calcine at 800 °C for 4 h to obtain 25%Mo-0.5%K / Al2O3.

[0112] Using the above catalyst, waste rubber pyrolysis oil (olefin content 33%, of which C5-C) was processed in a fixed-bed reactor. 12 Terminal olefins accounted for 42%, with the remainder being internal olefins and >C. 12 The olefin metathesis reaction of olefins and ethylene was carried out under the following conditions: 300℃, 1.5 MPa, and ethylene mass hourly space velocity (MHV) of 1.5 h⁻¹. -1 The feed rate of the cracked oil was 1 mL / min. Samples were taken for analysis after 2 hours of reaction. C5-C 12 The yield of terminal olefins was 38.2%, but the pressure drop in the catalyst bed increased by 50% after 4 h of reaction, and the coke content in the product increased significantly, indicating severe carbon deposition and deactivation.

[0113] Comparative Example 6 Catalyst preparation: 5%Mo-0.05%K / Al2O3 S1: Weigh 0.919 g of ammonium molybdate and dissolve it in 100 mL of deionized water at 80℃; S2: Weigh 0.013 g of potassium nitrate and dissolve it in 100 mL of deionized water; S3: Add 10.0 g Al2O3 to the S1 solution and stir at room temperature for 4 h; evaporate at 60℃ and dry at 80℃ for 12 h; calcine at 600℃ for 4 h to obtain 5%Mo / Al2O3; S4: Add the product of S3 to the solution of S2 and impregnate at room temperature for 6 h; evaporate at 50℃ and dry at 80℃ for 6 h; calcine at 800℃ for 4 h to obtain 5%Mo-0.05%K / Al2O3.

[0114] Using the above catalyst, waste rubber pyrolysis oil (olefin content 33%, of which C5-C) was processed in a fixed-bed reactor. 12 Terminal olefins accounted for 42%, with the remainder being internal olefins and >C. 12 The olefin metathesis reaction of olefins and ethylene was carried out under the following conditions: 300℃, 1.5 MPa, and ethylene mass hourly space velocity (MHV) of 1.5 h⁻¹. -1 The feed rate of the cracked oil was 1 mL / min. Samples were taken for analysis after 2 hours of reaction. C5-C 12 The yield of terminal olefins was 22.1%, with a selectivity of 59.3%.

[0115] Comparative Example 7 Catalyst preparation: 5%Mo-8%K / Al2O3 S1: Weigh 0.919 g of ammonium molybdate and dissolve it in 100 mL of deionized water at 80℃; S2: Weigh 2.062 g of potassium nitrate and dissolve it in 100 mL of deionized water; S3: Add 10.0 g Al2O3 to the S1 solution and stir at room temperature for 4 h; evaporate at 60℃ and dry at 80℃ for 12 h; calcine at 600℃ for 4 h; S4: Add the product of S3 to the solution of S2 and impregnate at room temperature for 6 h; evaporate at 50℃ and dry at 80℃ for 6 h; calcine at 800℃ for 4 h to obtain 5%Mo-8%K / Al2O3.

[0116] Using the above catalyst, waste rubber pyrolysis oil (olefin content 33%, of which C5-C) was processed in a fixed-bed reactor. 12 Terminal olefins accounted for 42%, with the remainder being internal olefins and >C. 12 The olefin metathesis reaction of olefins and ethylene was carried out under the following conditions: 300℃, 1.5 MPa, and ethylene mass hourly space velocity (MHV) of 1.5 h⁻¹. -1 The feed rate of the cracked oil was 1 mL / min. Samples were taken for analysis after 2 hours of reaction. C5-C 12 The yield of terminal olefins was 31.5%, with a selectivity of 48.7%.

[0117] Comparative Example 8 Catalyst preparation: 15%Mo-5%K / Al2O3 S1: Weigh 2.759 g of ammonium molybdate and dissolve it in 100 mL of deionized water at 80℃; S2: Weigh 0.646 g of potassium nitrate and dissolve it in 100 mL of deionized water; S3: Add 10.0 g Al2O3 to the S1 solution and stir at room temperature for 4 h; evaporate at 60℃ and dry at 80℃ for 12 h; calcine at 600℃ for 4 h; S4: Add the product of S3 to the solution of S2 and impregnate at room temperature for 6 h; evaporate at 50 °C and dry at 80 °C for 6 h; calcine at 800 °C for 4 h to obtain 15%Mo-5%K / Al2O3.

[0118] Using the above catalyst, waste rubber pyrolysis oil (olefin content 33%, of which C5-C) was processed in a fixed-bed reactor. 12 Terminal olefins accounted for 42%, with the remainder being internal olefins and >C. 12 The olefin metathesis reaction of olefins and ethylene was carried out under the following conditions: 300℃, 1.5 MPa, and ethylene mass hourly space velocity (MHV) of 1.5 h⁻¹. -1The feed rate of the cracked oil was 1 mL / min. After 2 hours of reaction, significant pulverization occurred, making it impossible to maintain stable operation of the fixed bed.

[0119] Comparative Example 9 Catalyst preparation: 5%Mo-1.5%K / Al2O3 S1: Weigh 0.919 g of ammonium molybdate and 0.388 g of potassium nitrate, dissolve them together in 100 mL of deionized water, and stir at 80°C until completely dissolved; S2: Add 10.0 g of Al2O3 particles to the mixed solution and stir and impregnate at room temperature for 4 h; S3: Vacuum evaporate to dryness at 60℃, then vacuum dry at 80℃ for 12 h; S4: First, calcine at 600℃ for 4 h, then raise the temperature to 800℃ and calcine for 4 h to obtain the co-impregnated catalyst.

[0120] Using the above catalyst, waste rubber pyrolysis oil (olefin content 33%, of which C5-C) was processed in a fixed-bed reactor. 12 Terminal olefins accounted for 42%, with the remainder being internal olefins and >C. 12 The olefin metathesis reaction of olefins and ethylene was carried out under the following conditions: 300℃, 1.5 MPa, and ethylene mass hourly space velocity (MHV) of 1.5 h⁻¹. -1 The feed rate of the cracked oil was 1 mL / min. Samples were taken for analysis after 2 hours of reaction. C5-C 12 The yield of terminal olefins was 36.4%, with a selectivity of 59.8%.

[0121] Comparative Example 10 Catalyst preparation: 5%Mo-1.5%K / Al2O3 S1: Weigh 0.388 g of potassium nitrate and dissolve it in 100 mL of deionized water; S2: Add 10.0 g Al2O3 to the S1 solution and stir at room temperature for 6 h; evaporate at 50℃ and dry at 80℃ for 6 h; calcine at 800℃ for 4 h to obtain 1.5% K / Al2O3; S3: Weigh 0.919 g of ammonium molybdate and dissolve it in 100 mL of deionized water at 80℃; S4: Add the support obtained in S2 to the S3 solution and stir at room temperature for 4 h; evaporate at 60℃ and dry at 80℃ for 12 h; calcine at 600℃ for 4 h to obtain the reverse impregnated catalyst.

[0122] Using the above catalyst, waste rubber pyrolysis oil (olefin content 33%, of which C5-C) was processed in a fixed-bed reactor. 12 Terminal olefins accounted for 42%, with the remainder being internal olefins and >C. 12The olefin metathesis reaction of olefins and ethylene was carried out under the following conditions: 300℃, 1.5 MPa, and ethylene mass hourly space velocity (MHV) of 1.5 h⁻¹. -1 The feed rate of the cracked oil was 1 mL / min. Samples were taken for analysis after 2 hours of reaction. C5-C 12 The yield of terminal olefins was 33.7%, with a selectivity of 60.1%.

[0123] Comparative Example 11 Catalyst: Commercial Grubbs second-generation catalyst ((H2IMes)(PCy3)Cl2Ru=CHPh) S1: Add 10 mL of waste plastic pyrolysis oil and 0.005 mmol of Grubbs II catalyst to the high-pressure reactor; S2: Seal the reactor, replace it with N2 three times, and then introduce ethylene to 1.5 MPa; S3: Heat to 300℃, stir (500 rpm), and react for 2 h; take a sample for analysis; continue the reaction for 4 h, and take a sample again.

[0124] Samples were taken for analysis 2 hours after the reaction, C5-C 12 The yield of terminal olefins was 41.2%, with a selectivity of 68.5%; analysis was performed on samples taken 4 h after the reaction, showing that C5-C... 12 The yield of terminal olefins was 18.5%, the solution turned black, precipitation occurred, and the catalyst decomposed significantly.

[0125] Table 1. Performance Comparison of Mo-Additive / Al2O3 System (Waste Plastic Pyrolysis Oil, 300℃, 1.5 MPa)

[0126] Table 2. Performance Comparison of W-Additive / SiO2 System (Waste Tire Pyrolysis Oil, 400℃, 2 MPa)

[0127] Table 3. Performance Comparison of Re-Additive / TiO2 System (Waste Rubber Pyrolysis Oil, 450℃, 2.5 MPa)

[0128] Table 4 Comparison with existing technologies (homogeneous catalysts)

[0129] The above embodiments show that: (1) C5-C can only be achieved when the active ingredient, auxiliaries, and carrier are within the scope of the claims and are prepared using a stepwise impregnation method. 12 The technology achieves a 25%-60% increase in terminal olefin yield and a 50%-70% selectivity. (2) This invention is the first to successfully apply olefin metathesis technology to real cracking oil systems such as waste plastics / tires / rubber, solving the core problems of low activity of existing heterogeneous catalysts and high cost and instability of homogeneous catalysts; (3) All embodiments fall within the scope of protection of the claims, fully supporting the inventiveness and utility of the patent.

[0130] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for increasing C5-C content in cracked oils 12 An olefin metathesis catalyst with a liquid-terminated olefin content is characterized by, The catalyst is a supported metal oxide catalyst, comprising, by weight percentage: 1~20wt% of an active component, wherein the active component is at least one element selected from W, Mo and Re or an oxide thereof; 0.1~6wt% of additives, wherein the additives are one of P, Ga, K and Ca or oxides thereof; 80-99 wt% of a support, wherein the support is at least one of SiO2, Al2O3 and TiO2; The catalyst is prepared by the following method: S1. Mix a certain amount of soluble salts of Mo, W and / or Re with water to obtain an aqueous solution of Mo, Wo and / or Re; S2. Mix a certain amount of soluble salts of P, Ga, K or Ca with water to obtain an aqueous solution of P, Ga, K or Ca. S3. Add a certain amount of support particles to an aqueous solution of Mo, Wo and / or Re, impregnate for 3-6 hours, and then perform rotary evaporation, drying and calcination in sequence to obtain an intermediate catalyst with supported active components. S4. The intermediate catalyst is added to the aqueous solution of P, Ga, K or Ca and impregnated for 4-8 hours, followed by rotary evaporation, drying and calcination to obtain the supported metal oxide catalyst.

2. The olefin metathesis catalyst according to claim 1, characterized in that, The active component contains 3 to 10 wt% of at least one element of W, Mo, and Re or its oxide.

3. The olefin metathesis catalyst according to claim 1, characterized in that, The content of the auxiliary agent P, Ga, K or Ca element is 0.1~3wt%.

4. The olefin metathesis catalyst according to claim 1, characterized in that, The carrier is at least one of SiO2, Al2O3 and TiO2, with a content of 90~97wt%.

5. The olefin metathesis catalyst according to claim 1, characterized in that, The soluble salt of Mo mentioned in step S1 is selected from at least one of ammonium heptamolybdate, ammonium molybdate, and molybdenum nitrate; The soluble salt of W is ammonium metatungstate, and the soluble salt of Re is ammonium perrhenate. Preferably, the soluble salt of Mo is ammonium molybdate.

6. The olefin metathesis catalyst according to claim 1, characterized in that, The auxiliary agent source mentioned in step S2 is a P source, Ga source, K or Ca source; The soluble salt of P is selected from at least one of phosphoric acid, ammonium phosphate, ammonium dihydrogen phosphate, and ammonium metaphosphate. The soluble salt of Ga is selected from at least one of gallium nitrate, gallium sulfate, and gallium chloride; The soluble salt of K is selected from at least one of potassium nitrate, potassium sulfate, and potassium chloride; The soluble salt of Ca is selected from at least one of calcium nitrate, calcium acetate, and calcium chloride; Preferably, the soluble salt of P is ammonium dihydrogen phosphate; Preferably, the soluble salt of Ga is gallium nitrate; Preferably, the soluble salt of K is potassium nitrate; Preferably, the soluble salt of Ca is calcium nitrate.

7. The olefin metathesis catalyst according to claim 1, characterized in that, The rotary evaporation temperature in step S3 is 60-80℃, the drying temperature is 60-100℃, the drying time is 6-12h, the calcination temperature is 500-800℃, and the calcination time is 2-8h.

8. The olefin metathesis catalyst according to claim 1, characterized in that, The rotary evaporation temperature in step S4 is 50-80℃, the drying temperature is 80-120℃, the drying time is 6-12h, the calcination temperature is 600-900℃, and the calcination time is 4-8h.

9. A method for increasing C5-C content in cracked oils 12 The method for determining the content of liquid-terminated olefins is characterized by, Using the olefin metathesis catalyst as described in any one of claims 1-8, at a reaction temperature of 100–500 °C, a reaction pressure of 0–3 MPa, and an ethylene mass hourly space velocity of 0.1–10 h⁻¹ -1 Under certain conditions, ethylene is subjected to a metathesis reaction with cracked oil.

10. The method according to claim 9, characterized in that, The cracked oil includes petroleum cracked oil, waste tire cracked oil, waste plastic and waste rubber cracked oil, and distillation components or the above components that have undergone dehydrogenation treatment.

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