A method for enhancing the synthesis of high-density aviation fuel through CO2 hydrogenation coupled with polycyclic aromatic hydrocarbon alkylation using a dual-site regulation strategy.

Abstract

This invention discloses a method for enhancing the synthesis of high-density aviation fuel through CO2 hydrogenation coupled with polycyclic aromatic hydrocarbon alkylation using a dual-site regulation strategy, employing a multifunctional M1ZnZrO42 ... x / M2β catalyst, which comprises M2β molecular sieve and M1ZnZrO x A homogeneous mixture, M2β represents a β-type molecular sieve loaded with the metal element M2, where M2 is one or more of Zn, Cu, Co, Fe, and Mo, and M1ZnZrO x This refers to a Zn-Zr composite oxide doped with a metallic element M1, where M1 is one or more of Ga, Ce, La, Mn, and Pr; it is produced by passing the catalyst through an M2β molecular sieve and M1ZnZrO. x The resulting dual active sites catalyze the CO2 hydrogenation coupled with the alkylation of polycyclic aromatic hydrocarbons to synthesize high-density aviation fuel. This invention improves the space-time yield of sustainable high-density aviation fuel.

Description

Technical Field

[0001] This invention belongs to the field of organocatalytic synthesis, specifically relating to a multifunctional M1ZnZrO x / M2β catalysts and their applications. Background Technology

[0002] High-density aviation fuel is the primary energy source for systems such as drones, missiles, and fighter jets, and is a key factor determining the overall performance of aerospace equipment. Aerospace vehicles have stringent requirements for fuel energy density, cryogenic performance, and safety. The current energy supply method, primarily based on liquid hydrocarbon fuels, is unlikely to be replaced by other energy forms such as electricity and hydrogen in the short term. Therefore, developing sustainable high-density aviation fuel has become an important technological approach to meeting the growing fuel demands of the aerospace sector and achieving dual-carbon goals.

[0003] Currently, sustainable aviation fuel production mainly utilizes technologies such as hydrogenated oleate (HEFA), gasification-Fischer-Tropsch synthesis (FT), alcohol-to-oil (ATJ), and electro-hydraulic conversion (PTL). Among these, the PTL process, based on the synthesis of CO2 and green hydrogen, can achieve a 99% reduction in carbon emissions and is not limited by raw materials, making it a core pathway to achieving zero carbon emissions in the aviation industry. However, due to the chemical inertness of CO2 and the high C / C bond coupling energy barrier during hydrocarbon molecule construction, existing technologies struggle to synthesize high-density aviation fuel components such as alkyl polycyclic hydrocarbons, failing to meet the high energy density (ρ≥0.85g / mL) requirements of advanced aircraft. Therefore, designing feasible reaction pathways and constructing high-performance catalysts to directionally convert CO2 and green hydrogen into high-density aviation fuel has become a critical challenge that urgently needs to be overcome in this field.

[0004] In recent years, metal oxide-molecular sieve (OX-ZEO) composite catalytic systems have attracted widespread attention in the field of CO2 conversion. While the carbon number of lignin-derived polycyclic aromatic hydrocarbons (PAHs) such as naphthalene and phenanthrene is compatible with that of aviation fuels, their application in high-density fuels is limited by their low hydrogen content, poor low-temperature performance, and tendency to carbonize during combustion. Structure-property relationships of hydrocarbon fuel molecules indicate that constructing polycyclic hydrocarbon components can significantly improve the density and bulk calorific value of aviation fuels, and alkyl branched structures can improve their low-temperature performance. Therefore, by coupling CO2 hydrogenation with the alkylation of lignin-derived PAHs, a new pathway for the synthesis of sustainable high-density aviation fuels using alkyl PAHs can be developed.

[0005] Metal oxides (OX) with redox properties can catalyze the hydrogenation of CO2 to form H2. x CO*, acidic molecular sieves (ZEO) can activate polycyclic aromatic hydrocarbons and H+. x CO* alkylation produces alkyl polycyclic aromatic hydrocarbons. The applicant disclosed a bifunctional MeO in patent CN119771479A. xThe synthesis method of / AZE catalyst and its catalytic CO2 hydrogenation to synthesize high-density aviation fuel have been developed. However, this catalyst exhibits high selectivity for the byproduct CO in high-temperature reactions, resulting in low carbon utilization, and its activation capacity for CO2 is insufficient. Furthermore, the strong acidity of acidic molecular sieves easily induces cracking and continuous alkylation reactions, leading to a decrease in the yield of alkyl polycyclic aromatic hydrocarbon products, which are the sustainable components of high-density aviation fuel. Therefore, improving the coupling performance of CO2 hydrogenation and polycyclic aromatic hydrocarbon alkylation reactions, and reducing CO formation, is currently the main challenge.

[0006] To address the aforementioned problems, this invention proposes a multifunctional M1ZnZrO x The / M2β catalyst enhances the synthesis of sustainable high-density aviation fuels through CO2 hydrogenation coupled with polycyclic aromatic hydrocarbon alkylation using a dual-site regulation strategy, and modulates the composition of high-density fuel components from alkyl polycyclic hydrocarbons. Specifically, metal M1-doped ZnZrO is employed. x Oxides are used to increase oxygen vacancy concentration and construct asymmetric Zn-O-Me (Me = M1, Zr) active sites, promoting CO2 activation and the formation of alkylation active intermediates. Metallic M2 is used to modify acidic molecular sieves, optimizing the distribution of Brønsted (B) and Lewis (L) acids. A dual-site regulation strategy is employed to synergistically regulate oxygen vacancies and acidic sites, inhibiting CO formation and thus enhancing the catalytic efficiency of polycyclic aromatic hydrocarbon (PAH) alkylation. This enables the efficient synthesis of high-density aviation fuels through CO2 hydrogenation coupled with PAH alkylation. Summary of the Invention

[0007] To address the aforementioned technical problems in the existing technology, the present invention aims to provide a multifunctional M1ZnZrO x / M2β catalysts and their applications.

[0008] The technical solution adopted in this invention is as follows: A method for enhancing the synthesis of high-density aviation fuel through CO2 hydrogenation coupled with polycyclic aromatic hydrocarbon alkylation using a dual-site regulation strategy, wherein the method employs a multifunctional M1ZnZrO x / M2β catalyst, which comprises M2β molecular sieve and M1ZnZrO x A homogeneous mixture, M2β represents a β-type molecular sieve loaded with the metal element M2, where M2 is one or more of Zn, Cu, Co, Fe, and Mo, and M1ZnZrO x This indicates a Zn-Zr composite oxide doped with a metallic element M1, where M1 is one or more of Ga, Ce, La, Mn, and Pr. Through the M2β molecular sieve and M1ZnZrO of the catalyst x The resulting dual active sites catalyze the hydrogenation of CO2 coupled with the alkylation of polycyclic aromatic hydrocarbons to synthesize high-density aviation fuel.

[0009] Furthermore, in the catalyst, M2β and M1ZnZrO x The mass ratio is 1:0.8-1.5.

[0010] Furthermore, in the M2β molecular sieve, the molar ratio of M2 to the mass of the β-type molecular sieve is 0.2-0.8 mmol: 1 g.

[0011] Furthermore, M1ZnZrO x In this mixture, the molar amount of Zr is 6-8 times that of Zn, and the molar amount of M1 is 3-7% of the total molar amount of M1, Zn, and Zr.

[0012] Furthermore, the M2β and M1ZnZrO x The mass ratio is 1:1-1.2, the molar mass of M2 to the mass of β-type molecular sieve is 0.4-0.5 mmol:1g; the molar mass of Zr is 7-7.5 times that of Zn, and the molar mass of M1 is 4-5% of the total molar mass of M1, Zn and Zr.

[0013] Further, the preparation method of M2β is as follows: dissolve the M2 source in deionized water, add β molecular sieve under stirring, and stir at 60-90℃ for 5-8h; then remove excess water by rotary evaporation, dry, grind thoroughly until the particle size distribution is stable, and calcine in a muffle furnace at 450-600℃ for 4-9h to obtain M2β molecular sieve.

[0014] Furthermore, M1ZnZrO x The preparation method is as follows: S1: Dissolve the Zn source and Zr source in anhydrous ethanol and stir in a water bath at 25-40℃ for 30-90 min; then add the M1 source and continue stirring for 30-90 min. S2: Add the precipitant solution dropwise to the solution obtained in step S1, stir the reaction thoroughly, and allow the precipitation to be complete; S3: Collect the solid precipitate, wash and dry it, and calcine it in a muffle furnace at 450-550℃ for 4-9 hours to obtain M1ZnZrO. x .

[0015] Further, in step S2, the precipitant is one or more of ammonium carbonate, sodium carbonate, oxalic acid, and ammonia water, and the reaction is carried out under stirring in a water bath at 25-40℃ for 90-150 min.

[0016] Furthermore, the catalyst is prepared by mixing M2β and M1ZnZrO. x The catalyst is obtained by grinding the material thoroughly in a mortar, then pressing it into tablets and granulating it.

[0017] Furthermore, the method of the present invention specifically includes the following steps: Step 1: Combine the multi-functional M1ZnZrO x / M2β catalyst is tableted, granulated, and then loaded into a fixed-bed reactor; Step 2: Introduce a N2-H2 mixture and heat to 300-400℃ for 2.0-6.0 hours to activate the catalyst; Step 3: Using N2 as an internal standard gas, prepare a mixture of CO2, H2 and N2 as the gas-phase reaction raw material; dissolve polycyclic aromatic hydrocarbons in an alkane solvent to prepare a liquid-phase reaction raw material, wherein the polycyclic aromatic hydrocarbons are one or more of naphthalene, phenanthrene and their alkyl-substituted derivatives, and the alkane solvent is one or more of decahydronaphthalene, cyclohexane, octane and heptane. Step 4: After activation in Step 2, introduce gaseous and liquid reactants, adjust the reaction pressure to 2.0-6.0 MPa, the reaction temperature to 250-500℃, and the gas hourly space velocity (GHSV) to 3000-48000 h⁻¹. -1 The liquid hourly space velocity (WHSV) is 5-50 h⁻¹. -1 Under certain conditions, a CO2 hydrogenation conversion reaction is carried out to obtain a product of CO2 hydrogenation coupled with polycyclic aromatic hydrocarbon alkylation, which is high-density aviation fuel.

[0018] Furthermore, in step 2, the volume ratio of H2 to N2 is 1:2-6, preferably 1:4-5, and the reduction temperature is 300-350℃.

[0019] Furthermore, in step S3, the volume fractions of each component in the gas phase reaction feedstock are 20-25% CO2, 65-75% H2, and the balance is N2, and the mass concentration of polycyclic aromatic hydrocarbons in the liquid phase reaction feedstock is 2-15%.

[0020] Furthermore, in step S4, the reaction temperature is 360±20℃ and the reaction pressure is 4.0±0.5MPa.

[0021] Compared with the prior art, the beneficial effects achieved by the present invention are: 1) This invention proposes a dual-site regulation strategy to enhance the synthesis of sustainable high-density aviation fuel through CO2 hydrogenation coupled with polycyclic aromatic hydrocarbon alkylation. Metal M1 is used to regulate the active sites of ZnZrOx oxides, increasing oxygen vacancy concentration and constructing asymmetric Zn-O-Me (Me=M1, Zr) activation sites, promoting CO2 activation and the formation of alkylation active intermediates. Metal M2 is used to modify acidic molecular sieves, optimizing the distribution of Brønsted (B) and Lewis (L) acids. This dual-site regulation strategy enhances the catalytic activity of CO2, inhibits CO formation, exhibits stronger hydrogenation coupled catalytic performance, and improves the space-time yield of sustainable high-density aviation fuel.

[0022] 2) The composition of high-density fuel components of alkyl polycyclic hydrocarbons can be controlled by using a dual-site catalyst regulation strategy. Attached Figure Description

[0023] Figure 1 Ga5ZnZrO x Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) images of oxides and Zn3β molecular sieves; Figure 2 The fuel process of the high-density aviation fuel sample HD synthesized in this invention has an ignition delay time of 2382ms, exhibiting good combustion performance. Detailed Implementation

[0024] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0025] Comparative Example 1: Multifunctional ZnZrO x / β catalyst synthesis 1) Weigh 2.992 mmol zinc nitrate and 20.987 mmol zirconium nitrate and dissolve them in 150 mL anhydrous ethanol. Stir at 600 rpm for 45 min in a 30 °C constant temperature water bath.

[0026] 2) Weigh 53.983 mmol of oxalic acid and dissolve it in 50 mL of anhydrous ethanol. Add the oxalic acid solution dropwise to the metal salt solution prepared in step 1) using a constant-pressure dropping funnel, and continue stirring for 120 min. Then, separate and collect the resulting solid precipitate by centrifugation, and refract it three times with anhydrous ethanol. Place the washed solid in an oven and dry it at 110 ℃ for 12 h. Then, place the dried sample in a muffle furnace and calcine it at 500 ℃ for 6 h to obtain ZnZrO. x Oxides.

[0027] 3) Add 500 mg of ZnZrO x After being mixed with 500 mg of β-zeolite, the mixture was placed in an agate mortar and ground thoroughly for 20 minutes to obtain the prepared ZnZrO. x / β catalyst. The ground powder was then pressed using a powder press, and then crushed and sieved to obtain 40-60 mesh particles.

[0028] Example 1: Multifunctional Ga3ZnZrO x / β catalyst synthesis 1) Weigh 2.992 mmol zinc nitrate and 20.987 mmol zirconium nitrate and dissolve them in 150 mL anhydrous ethanol. Stir at 600 rpm for 45 min in a 30 °C constant temperature water bath. Then weigh 0.742 mmol gallium nitrate and add it to the above solution. Continue stirring for 30 min.

[0029] 2) Weigh 55.31g of oxalic acid and dissolve it in 50mL of anhydrous ethanol. Using a constant-pressure dropping funnel, add the oxalic acid solution dropwise to the mixed metal salt solution prepared in step 1), and continue stirring for 120min. Then, separate and collect the resulting solid precipitate by centrifugation, and refract it three times with anhydrous ethanol. Place the washed solid in an oven and dry it at 110℃ for 12h. Then, place the dried sample in a muffle furnace and calcine it at 500℃ for 6h to obtain Ga3ZnZrO. x Oxides.

[0030] 3) Add 500 mg of Ga3ZnZrO x After being mixed with 500 mg of β-zeolite, the mixture was placed in an agate mortar and ground thoroughly for 20 minutes to obtain the prepared Ga3ZnZrO. x / β catalyst. The ground powder was then pressed and sieved using a powder press to obtain 40-60 mesh particles.

[0031] Example 2: Multifunctional Ga5ZnZrO x / β catalyst synthesis 1) Weigh 2.992 mmol zinc nitrate and 20.987 mmol zirconium nitrate and dissolve them in 150 mL anhydrous ethanol. Stir at 600 rpm for 45 min in a 30 °C constant temperature water bath. Then weigh 1.262 mmol gallium nitrate and add it to the above solution. Continue stirring for 30 min.

[0032] 2) Weigh 57.59g of oxalic acid and dissolve it in 50mL of anhydrous ethanol. Using a constant-pressure dropping funnel, add the oxalic acid solution dropwise to the mixed metal salt solution prepared in step 1), and continue stirring for 120min. Then, separate and collect the resulting solid precipitate by centrifugation, and refract it three times with anhydrous ethanol. Place the washed solid in an oven and dry it at 110℃ for 12h. Then, place the dried sample in a muffle furnace and calcine it at 500℃ for 6h to obtain Ga₅ZnZrO₂. x Oxides.

[0033] 3) Add 500 mg of Ga5ZnZrO x After being mixed with 500 mg of β-zeolite, the mixture was placed in an agate mortar and ground thoroughly for 20 minutes to obtain the prepared Ga5ZnZrO. x / β catalyst. The ground powder was then pressed and sieved using a powder press to obtain 40-60 mesh particles.

[0034] Example 3: Multifunctional Ga5ZnZrO x / Zn3β catalyst synthesis 1) Weigh 2.992 mmol zinc nitrate and 20.987 mmol zirconium nitrate and dissolve them in 150 mL anhydrous ethanol. Stir at 600 rpm for 45 min in a 30 °C constant temperature water bath. Then weigh 1.262 mmol gallium nitrate and add it to the above solution. Continue stirring for 30 min.

[0035] 2) Weigh 57.59g of oxalic acid and dissolve it in 50mL of anhydrous ethanol. Using a constant-pressure dropping funnel, add the oxalic acid solution dropwise to the mixed metal salt solution prepared in step 1), and continue stirring for 120min. Then, separate and collect the resulting solid precipitate by centrifugation, and refract it three times with anhydrous ethanol. Place the washed solid in an oven and dry it at 110℃ for 12h. Then, place the dried sample in a muffle furnace and calcine it at 500℃ for 6h to obtain Ga₅ZnZrO₂. x Oxides.

[0036] 3) Weigh 1.892 mmol of zinc nitrate and dissolve it in 40 mL of deionized water. Stir at 600 rpm for 30 min in a 30℃ constant temperature water bath. Slowly add 4 g of β-molecular sieve and stir at 80℃ for 6 h. Remove excess water using a rotary evaporator at 50℃, and dry at 110℃ for 8 h. Then place the dried sample in a muffle furnace and calcine at 550℃ for 6 h to obtain Zn3β-molecular sieve.

[0037] 4) Add 500 mg of Ga5ZnZrO x After being mixed with 500 mg of Zn3β molecular sieve, the mixture was placed in an agate mortar and ground thoroughly for 20 min to obtain the prepared multifunctional Ga5ZnZrO. x / Zn3β catalyst. The ground powder was then pressed and sieved using a powder press to obtain 40-60 mesh particles.

[0038] Example 4: Multifunctional Ga5ZnZrO x / Zn5β catalyst synthesis 1) Weigh 2.992 mmol zinc nitrate and 20.987 mmol zirconium nitrate and dissolve them in 150 mL anhydrous ethanol. Stir at 600 rpm for 45 min in a 30 °C constant temperature water bath. Then weigh 1.262 mmol gallium nitrate and add it to the above solution. Continue stirring for 30 min.

[0039] 2) Weigh 57.59g of oxalic acid and dissolve it in 50mL of anhydrous ethanol. Using a constant-pressure dropping funnel, add the oxalic acid solution dropwise to the mixed metal salt solution prepared in step 1), and continue stirring for 120min. Then, separate and collect the resulting solid precipitate by centrifugation, and refract it three times with anhydrous ethanol. Place the washed solid in an oven and dry it at 110℃ for 12h. Then, place the dried sample in a muffle furnace and calcine it at 500℃ for 6h to obtain Ga₅ZnZrO₂. x Oxides.

[0040] 3) Weigh 3.220 mmol of zinc nitrate and dissolve it in 40 mL of deionized water. Stir at 600 rpm for 30 min in a 30℃ constant temperature water bath. Slowly add 4 g of β-molecular sieve and stir at 80℃ for 6 h. Remove excess water using a rotary evaporator at 50℃, and dry at 110℃ for 8 h. Then place the dried sample in a muffle furnace and calcine at 550℃ for 6 h to obtain Zn3β-molecular sieve.

[0041] 4) Add 500 mg of Ga5ZnZrO x After being mixed with 500 mg of Zn3β molecular sieve, the mixture was placed in an agate mortar and ground thoroughly for 20 min to obtain the prepared multifunctional Ga5ZnZrO. x / Zn3β catalyst. The ground powder was then pressed and sieved using a powder press to obtain 40-60 mesh particles.

[0042] Example 5: Multifunctional Ce5ZnZrO x / Zn3β catalyst synthesis 1) Weigh 2.992 mmol zinc nitrate and 20.987 mmol zirconium nitrate and dissolve them in 150 mL anhydrous ethanol. Stir at 600 rpm for 45 min in a 30 °C constant temperature water bath. Then weigh 1.262 mmol cerium nitrate and add it to the above solution. Continue stirring for 30 min.

[0043] 2) Weigh 57.59g of oxalic acid and dissolve it in 50mL of anhydrous ethanol. Using a constant-pressure dropping funnel, add the oxalic acid solution dropwise to the mixed metal salt solution prepared in step 1), and continue stirring for 120min. Then, separate and collect the resulting solid precipitate by centrifugation, and refract it three times with anhydrous ethanol. Place the washed solid in an oven and dry it at 110℃ for 12h. Then, place the dried sample in a muffle furnace and calcine it at 500℃ for 6h to obtain Ce₅ZnZrO₂. x Oxides.

[0044] 3) Weigh 1.892 mmol of zinc nitrate and dissolve it in 40 mL of deionized water. Stir at 600 rpm for 30 min in a 30℃ constant temperature water bath. Slowly add 4 g of β-molecular sieve and stir at 80℃ for 6 h. Remove excess water using a rotary evaporator at 50℃, and dry at 110℃ for 8 h. Then place the dried sample in a muffle furnace and calcine at 550℃ for 6 h to obtain Zn3β-molecular sieve.

[0045] 4) Add 500 mg of Ce5ZnZrO x After being mixed with 500 mg of Zn3β molecular sieve, the mixture was placed in an agate mortar and ground thoroughly for 20 min to obtain the prepared multifunctional Ce5ZnZrO. x / Zn3β catalyst. The ground powder was then pressed and sieved using a powder press to obtain 40-60 mesh particles.

[0046] Example 6: CO2 hydrogenation for high-density aviation fuel preparation based on functional coupling CO2 hydrogenation was carried out in a stainless steel tubular fixed-bed reactor with a quartz liner. The prepared multifunctional catalyst was mixed with quartz sand and loaded into the quartz liner of the stainless steel reaction tube. Quartz wool was used to fix the catalyst particles in the middle of the reaction tube before it was installed on the fixed-bed reactor. The fixed-bed pressure was adjusted to 4.0 MPa using nitrogen gas for leak testing. No significant pressure drop within 30 minutes indicated good sealing. After purging the high-pressure nitrogen, a hydrogen-nitrogen mixture was used to replace the nitrogen at atmospheric pressure. The hydrogen flow rate was adjusted to 20 mL / min, and the nitrogen flow rate to 80 mL / min. The catalyst was activated by reduction at 350℃ for 2.5 h. After catalyst activation, a mixed gas (CO2:H2:N2 volume ratio = 23:69:8) was used to adjust the reaction pressure to 4.0 MPa and the reaction temperature to 320-400℃. The liquid feed was a 5 wt% cyclohexane solution of the polycyclic aromatic hydrocarbon naphthalene. The gas hourly space velocity (GHSV) during the hydrogenation coupling reaction was 6000 h⁻¹. -1 The liquid hourly space velocity (WHSV) was 9.5 h⁻¹. -1 After the reaction reaches steady state, the liquid product is collected. The gaseous product is analyzed online using a multichannel gas chromatograph (Agilent 8890) with TCD and FID detectors, while the liquid product is analyzed offline using a single-channel chromatograph (Agilent 8890) with FID. CO2 is utilized in the reaction products primarily through three pathways: 1) coupling with polycyclic aromatic hydrocarbons to form high-density aviation fuel; 2) forming CO; 3) generating C1-C5 gaseous hydrocarbon molecules; and 4) forming dimethyl ether.

[0047] Table 1 shows the CO2 conversion performance data for the catalysts prepared in Comparative Examples 1 and Examples 1-5 in the catalytic CO2 hydrogenation coupled with polycyclic aromatic hydrocarbon naphthalene to produce sustainable high-density aviation fuel. Table 2 shows the carbon utilization pathway data, and Table 3 shows the liquid-phase product selectivity data for the high-density aviation fuel. Reaction conditions: pressure 4.0 MPa, temperature 360℃, gas feedstock volume ratio CO2:H2:N2 = 23:69:8, liquid feedstock was a cyclohexane solution of polycyclic aromatic hydrocarbon naphthalene, and gas hourly space velocity (GHSV) was 6000 h⁻¹. -1 The liquid hourly space velocity (WHSV) was 9.5 h⁻¹. -1 .

[0048] Table 1. CO2 hydrogenation activity data of the catalysts prepared in Comparative Example 1 and Examples 1-5 .

[0049] As can be seen from the results in Table 1, the catalyst ZnZrO in Comparative Example 1 x / β exhibits only a 21.2% CO2 conversion rate at 360℃. When Ga is used to modify ZnZrO... x After the active sites are regulated, Ga3ZnZrO with a doping amount of 3% x The CO2 conversion rate was significantly enhanced on the β-catalyst, increasing to 23.3%. Further increasing the Ga content to 5% also improved the CO2 conversion rate to 23.7%. Furthermore, the CO2 conversion rate was also improved by regulating the active sites of the β-zeolite. For example, Ga₅ZnZrO₂... x The / Zn3β catalyst exhibited a conversion rate of 25.6%. This indicates that the use of metal M1 for ZnZrO2... x Dual regulation of active sites and metal M2-catalyzed β-active sites can significantly improve the catalytic conversion performance of CO2, which is conducive to the generation of more active intermediates and promotes the synthesis of sustainable high-density aviation fuel components.

[0050] Table 2. Data on carbon utilization pathways of CO2 during the catalytic process of the catalysts prepared in Comparative Example 1 and Examples 1-5. .

[0051] The hydrogenation coupling selectivity in Table 2 refers to the selectivity of carbon in CO2 to generate alkylation active intermediates. These alkylation active intermediates can participate in the alkylation reaction of polycyclic aromatic hydrocarbons and can be effectively utilized. Furthermore, other intermediates from CO2 conversion, such as CO, C1-C5 gaseous hydrocarbons, and dimethyl ether, cannot participate in the alkylation coupling reaction of polycyclic aromatic hydrocarbons.

[0052] Table 2 clearly shows that after Ga regulation, Ga3ZnZrO x / β and Ga5ZnZrOx The decreased CO selectivity of / β and the increased hydrogen coupling selectivity indicate that more carbon from CO2 participates in the alkylation reaction, forming a sustainable high-density aviation fuel composition. The use of metallic M1 to alkylate ZnZrO x Catalysts with dual regulation of active sites and metal M2-catalyzed β-active sites exhibit the best hydrogenation coupling selectivity, among which Ga5ZnZrO x The hydrogenation coupling selectivity of / Zn3β reached 86.3%, while the selectivity for CO was the lowest.

[0053] Table 3. Selectivity of alkylnaphthalenes in the liquid-phase products of CO2 hydrogenation coupled with polycyclic aromatic hydrocarbon naphthalene alkylation catalyzed by the catalysts prepared in Comparative Examples 1 and Examples 1-4 .

[0054] Table 3 shows that the liquid-phase products are mainly monomethylnaphthalene, followed by dimethylnaphthalene and trimethylnaphthalene, with a small amount of ethylnaphthalene. These alkyl polycyclic aromatic hydrocarbon components are high-density aviation fuel components with excellent performance. Additionally, Ga was used to prepare ZnZrO. x After regulating the active site of / β, Ga3ZnZrO x / β and Ga5ZnZrO x The / β catalyst enhances the selectivity of polyalkyl-substituted products such as dimethylnaphthalene and trimethylnaphthalene. This is due to the increased CO2 conversion, which facilitates the formation of more alkylation intermediates that react with naphthalene, thus improving the selectivity of polyalkyl-substituted products. Furthermore, the catalyst reacts with Ga5ZnZrO... x Compared to β-catalysts, Ga5ZnZrO2 was improved by using Zn to modulate the active sites of the molecular sieve. x / Zn3β and Ga5ZnZrO x The Zn5β catalyst improves the selectivity of monomethylnaphthalene because Zn modulates the acidity of the β-zeolite, reducing the acidity of the zeolite and thus weakening the continuous alkylation reaction, thereby increasing the selectivity of monomethylnaphthalene. These data indicate that by regulating the active sites of ZnZrOx oxide and β-zeolite, the compositional distribution of high-density aviation fuel in the liquid product can be changed, which can further affect the combustion properties of the prepared high-density aviation fuel.

[0055] Table 4 shows the density data of the prepared high-density aviation fuel after being mixed and blended with JP-10. JP-10 is a widely used petroleum-based high-density aviation fuel with a density of 0.936 g / mL. After being mixed and blended with the high-density aviation fuel component synthesized in this invention, the density was significantly improved. When the doping amount of the high-density aviation fuel synthesized in this invention was 15 wt%, the density increased to 0.945 g / mL, which proves the good energy density and excellent application prospects of the high-density aviation fuel component synthesized in this invention.

[0056] Table 4. Density data of the synthesized high-density aviation fuel components and JP-10 after blending. .

[0057] Figure 1 Ga5ZnZrO x Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) images of oxides and Zn3β molecular sieves. Figure 1 The TEM image in part a shows Ga5ZnZrO x Composed of uniformly dispersed amorphous nanoparticles with an average particle size of approximately 14.1 nm, lattice fringes with an interplanar spacing of approximately 2.925 Å were observed in HRTEM images, belonging to the (101) crystal plane of ZrO2. Figure 1 (part b). This value is slightly smaller than the interplanar spacing of 2.950 Å for pure ZrO2(101), indicating that it is Ga-doped with ZnZrO. x The framework causes lattice contraction. On the other hand, Zn3β molecular sieves exhibit an ellipsoidal morphology. Figure 1 Part c), HRTEM images show highly dispersed Zn clusters in the molecular sieve ( Figure 1 The average particle size of the d-part (marked by the white arrow) is concentrated at 2.05 nm. Notably, the molecular sieve also contains a high density of atomically dispersed Zn species, indicating that Zn exists in a dual dispersion state where single atoms and clusters coexist. This dispersion state plays a crucial role in regulating acidity and enhancing alkylation performance during the coupling reaction.

[0058] Example 7: Property Testing of Synthesized High-Density Aviation Fuel

[0059] The density of the synthesized high-density aviation fuel was measured using a Mettler Toledo DE40 densitometer. The combustion process was tested on a flat-plate ignition device, where the ignition temperature was maintained at 500°C, and the combustion process was captured using a high-speed camera. Results are shown below. Figure 2 As shown, the ignition delay time is shortened compared to the JP-10 alone.

[0060] The contents described in this specification are merely an enumeration of the implementation forms of the inventive concept, and the scope of protection of this invention should not be regarded as limited to the specific forms described in the embodiments.

Claims

1. A method for enhancing the synthesis of high-density aviation fuel through CO2 hydrogenation coupled with polycyclic aromatic hydrocarbon alkylation using a dual-site regulation strategy, characterized in that, The method employs a multifunctional M1ZnZrO x / M2β catalyst, which comprises M2β molecular sieve and M1ZnZrO x A homogeneous mixture, M2β represents a β-type molecular sieve loaded with the metal element M2, where M2 is one or more of Zn, Cu, Co, Fe, and Mo, and M1ZnZrO x This indicates a Zn-Zr composite oxide doped with a metallic element M1, where M1 is one or more of Ga, Ce, La, Mn, and Pr. Through the M2β molecular sieve and M1ZnZrO of the catalyst x The resulting dual active sites catalyze the coupling of CO2 hydrogenation with polycyclic aromatic hydrocarbon alkylation to synthesize high-density aviation fuel.

2. The method as described in claim 1, characterized in that, In the catalyst, M2β and M1ZnZrO x The mass ratio is 1:0.8-1.5; In M2β molecular sieve, the molar amount of M2 to the mass ratio of β-type molecular sieve is 0.2-0.8 mmol: 1g; M1ZnZrO x In this mixture, the molar amount of Zr is 6-8 times that of Zn, and the molar amount of M1 is 3-7% of the total molar amount of M1, Zn, and Zr.

3. The method as described in claim 2, characterized in that, The M2β and M1ZnZrO x The mass ratio is 1:1-1.2, the molar mass of M2 to the mass of β-type molecular sieve is 0.4-0.5 mmol:1g; the molar mass of Zr is 7-7.5 times that of Zn, and the molar mass of M1 is 4-5% of the total molar mass of M1, Zn and Zr.

4. The method as described in claim 1, characterized in that, The preparation method of M2β is as follows: dissolve the M2 source in deionized water, add β molecular sieve under stirring, and stir at 60-90℃ for 5-8h; then remove excess water by rotary evaporation, dry, grind thoroughly until the particle size distribution is stable, and calcine in a muffle furnace at 450-600℃ for 4-9h to obtain M2β molecular sieve.

5. The method as described in claim 1, characterized in that, M1ZnZrO x The preparation method is as follows: S1: Dissolve the Zn source and Zr source in anhydrous ethanol and stir in a water bath at 25-40℃ for 30-90 min; then add the M1 source and continue stirring for 30-90 min. S2: Add the precipitant solution dropwise to the solution obtained in step S1, stir the reaction thoroughly, and allow the precipitation to be complete; S3: Collect the solid precipitate, wash and dry it, and calcine it in a muffle furnace at 450-550℃ for 4-9 hours to obtain M1ZnZrO. x .

6. The method as described in claim 1, characterized in that, In step S2, the precipitant is one or more of ammonium carbonate, sodium carbonate, oxalic acid, and ammonia water, and the mixture is stirred and reacted in a water bath at 25-40℃ for 90-150 minutes.

7. The method as described in claim 1, characterized in that, The catalyst is prepared by mixing M2β and M1ZnZrO. x The catalyst is obtained by grinding the material thoroughly in a mortar, then pressing it into tablets and granulating it.

8. The method as described in claim 1, characterized in that, The method specifically includes the following steps: Step 1: Combine the multi-functional M1ZnZrO x / M2β catalyst is tableted, granulated, and then loaded into a fixed-bed reactor; Step 2: Introduce a N2-H2 mixture and heat to 300-400℃ for 2.0-6.0 hours to activate the catalyst; Step 3: Using N2 as an internal standard gas, prepare a mixture of CO2, H2 and N2 as the gas-phase reaction raw material; dissolve polycyclic aromatic hydrocarbons in an alkane solvent to prepare a liquid-phase reaction raw material, wherein the polycyclic aromatic hydrocarbons are one or more of naphthalene, phenanthrene and their alkyl-substituted derivatives, and the alkane solvent is one or more of decahydronaphthalene, cyclohexane, octane and heptane. Step 4: After activation in Step 2, introduce gaseous and liquid reactants, adjust the reaction pressure to 2.0-6.0 MPa, the reaction temperature to 250-500℃, and the gas hourly space velocity (GHSV) to 3000-48000 h⁻¹. -1 The liquid hourly space velocity (WHSV) is 5-50 h⁻¹. -1 Under certain conditions, a CO2 hydrogenation conversion reaction is carried out to obtain a product of CO2 hydrogenation coupled with polycyclic aromatic hydrocarbon alkylation, which is high-density aviation fuel.

9. The method as described in claim 7, characterized in that, In step 2, the volume ratio of H2 to N2 is 1:2-6, preferably 1:4-5, and the reduction temperature is 300-350℃.

10. The method as described in claim 7, characterized in that, In step S3, the volume fractions of each component in the gas phase reaction feedstock are 20-25% CO2, 65-75% H2, and the balance is N2, and the mass concentration of polycyclic aromatic hydrocarbons in the liquid phase reaction feedstock is 2-15%; in step S4, the reaction temperature is 360±20℃ and the reaction pressure is 4.0±0.5MPa.

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