Synthesis method of difunctional MeOx / AZE catalyst and application of difunctional MeOx / AZE catalyst in catalyzing CO2 hydrogenation to synthesize high-density aviation fuel

Abstract

The invention discloses a synthesis method of a bifunctional MeOx / AZE catalyst and application of the bifunctional MeOx / AZE catalyst in catalyzing CO2 hydrogenation to synthesize high-density aviation fuel, MeOx in the catalyst is a composite metal oxide of metal Zr and auxiliary metal M, the content of Zr in the metal is 75.0-95.0 mol%, and the content of the auxiliary metal M is 5.0-25.0 mol%; the auxiliary metal M is one or more of Zn, Ga, Ce, La and In; aZE is an acidic molecular sieve. The synthesized catalyst shows excellent CO2 hydrogenation coupling performance, the polycyclic aromatic hydrocarbon is introduced in the CO2 hydrogenation reaction for functional coupling reaction, the conversion of CO2 is promoted, the coupling reaction with the polycyclic aromatic hydrocarbon is carried out, the alkyl-substituted polycyclic hydrocarbon compound is synthesized, the difficulty that high-density aviation fuel components cannot be synthesized through single CO2 hydrogenation is overcome, and the synthesis efficiency is improved. And the selectivity of the high-density aviation fuel component alkyl polycyclic hydrocarbon product with excellent performance is enhanced.

Description

Technical Field

[0001] The present invention belongs to the field of organic catalytic synthesis, and specifically relates to a bifunctional MeO x / The synthesis method of AZE catalyst and its application in catalytic CO2 hydrogenation to synthesize high-density aviation fuel. Background Art

[0002] Liquid hydrocarbon fuel is the power source for aerospace vehicles and weapon systems such as missiles, and is the key to determining the speed, range and load of aircraft. The development of modern supersonic aircraft has also put forward higher requirements on the density of aviation fuel (ρ≥0.85g / mL). Compared with conventional aviation fuel (such as RP-3), high-density aviation fuel has higher density, volume calorific value and thermal oxidation stability. Under limited tank volume, it can greatly improve the range of missiles, the flight distance and load of aircraft. The development of green, sustainable and high-density aviation fuel has become an important technical path to achieve the green and rapid development of the aviation industry and the "dual carbon" goals.

[0003] Carbon dioxide (CO2) is an abundant, readily available, non-toxic and renewable carbon resource. It is an important way to achieve green and sustainable development of the aviation industry by converting it into alkyl polycyclic hydrocarbon high-density aviation fuel through coupling with green hydrogen. However, due to the chemical inertness, hydrogenation kinetic complexity and high carbon-carbon bond coupling energy barrier of CO2, it is easy to form C1 compounds such as CO and CH4, which is difficult to synthesize alkyl polycyclic hydrocarbon high-density aviation fuel (C8-C 16 ) is very difficult.

[0004] Professor Peter P. Edwards of Oxford University (Nature Communications, 2020, 11(1):6395) used an organic combustion method to construct a Fe-Mn-K catalyst to convert CO2 and green hydrogen into aviation fuel. 16 The selectivity of chain hydrocarbons is as high as 47.8%, but the density is low (ρ<0.78g / mL), and it cannot be used as a high-density aviation fuel. Tsinghua University (ACS Catalysis, 2022, 12(3):2023-2033) used nano ZnCr2O4 / Sbx-H-ZSM-5 catalyst to hydrogenate CO2 to synthesize C8-C 12 Monocyclic aromatic compounds are used as aromatic hydrocarbon components of aviation fuel, but the selectivity for high-density aviation fuel components such as bicyclic hydrocarbons in the hydrogenation products is not high.

[0005] Designing a suitable reaction pathway and constructing a high-performance hydrogenation catalyst to enhance the selectivity of alkyl polycyclic hydrocarbons are the key to catalytic CO2 hydrogenation to produce high-density aviation fuel with high energy density and excellent low-temperature performance.

[0006] Condensed aromatics are the main components of heavy oil and coal tar. With the exhaustion of fossil energy and the improvement of my country's coal liquefaction capacity, the output of heavy oil and coal tar is also increasing year by year, but due to the low reactivity caused by the high resonance energy and steric hindrance of condensed aromatics, its resource utilization has always been a difficult problem in refining, but condensed aromatics have a polycyclic structure and high energy density. The inventor carried out deep hydrogenation saturation synthesis of high-density aviation fuel components such as decalin and perhydrophenanthrene by condensed aromatics such as naphthalene and phenanthrene in the early stage, showing a density and volume calorific value superior to U.S. military high-density fuel JP-10, but saturated condensed aromatics lack alkyl substituents, and their viscosity and low-temperature fluidity are poor (CN113368891A, CN115197743A).

[0007] The introduction of alkyl substituents into polycyclic aromatic hydrocarbons can enhance the low-temperature performance of the fuel. Based on this, if CO2 hydrogenation is coupled with polycyclic aromatic hydrocarbon alkylation to prepare alkyl polycyclic aromatic hydrocarbons, and then hydrogenated and saturated, high-density aviation fuel with high energy density and excellent low-temperature performance can be prepared. At the same time, the resource utilization of CO2 and heavy oil is enhanced, and the problem that CO2 hydrogenation cannot synthesize high-density aviation fuel is overcome. Alkyl polycyclic aromatic hydrocarbons can be used as high-density aviation fuel components and compounded with other aviation fuels, or as a matrix to synthesize high-density aviation fuel with better performance through hydrogenation, isomerization, ring opening and other reactions; and polycyclic aromatic hydrocarbons can also be obtained from biomass, in which case the entire high-density aviation fuel preparation process is carbon neutral. However, there is currently no report on the preparation of high-density aviation fuel by coupling CO2 hydrogenation with polycyclic aromatic hydrocarbons.

[0008] In order to solve the above problems, a new route for synthesizing high-density aviation fuel components with excellent performance by CO2 hydrogenation is developed. The present invention adopts a coprecipitation method to synthesize MeO x / AZE bifunctional metal oxide-molecular sieve catalyst, CO2 hydrogenation reaction in the atmosphere of polycyclic aromatic hydrocarbons, CO2 hydrogenation and polycyclic aromatic hydrocarbon alkylation for functional coupling with high selectivity to synthesize high-density aviation fuel component alkyl polycyclic hydrocarbon compounds with excellent performance. The catalyst exhibits excellent hydrogenation performance and coupling efficiency, has high selectivity for alkyl polycyclic hydrocarbon products, and significantly improves the density of the fuel after mixing with JP-10, showing good fuel properties and has broad application prospects. Summary of the invention

[0009] In view of the above technical problems existing in the prior art, the present invention aims to provide a dual-functional MeO x / The synthesis method of AZE catalyst and its application in catalytic CO2 hydrogenation to synthesize high-density aviation fuel.

[0010] The technical solution adopted by the present invention is as follows:

[0011] A dual-function MeO x / AZE catalyst synthesis method, the MeO x It is a composite metal oxide of metal Zr and auxiliary metal M, wherein the total molar content of metal Zr and auxiliary metal M is 100%, wherein the content of Zr is 75.0-95.0 mol%, and the content of auxiliary metal M is 5.0-25.0 mol%;

[0012] The additive metal M is one or more of Zn, Ga, Ce, La, and In;

[0013] AZE is an acidic molecular sieve;

[0014] The synthesis method of the catalyst comprises the following steps:

[0015] 1) dissolving a Zr source and a M source in a solvent, and uniformly dispersing them by ultrasonication to prepare a mixed metal solution;

[0016] 2) adding the precipitant solution dropwise to the mixed metal solution in step 1), stirring the reaction sufficiently to allow complete precipitation;

[0017] 3) The precipitate obtained in step 2) is centrifuged, collected, dried, and calcined in a muffle furnace to obtain MeO x Metal oxides;

[0018] 4) MeO x The metal oxide and AZE molecular sieve are ground in a mortar to ensure that the metal oxide and the molecular sieve are in full contact.

[0019] That is, bifunctional MeO x / AZE catalyst.

[0020] Furthermore, in step 1), the solvent is anhydrous ethanol.

[0021] Furthermore, in step 2), the precipitant is oxalic acid, and the ratio of the molar amount of oxalic acid to the total molar amount of metal Zr and auxiliary metal M is 2-3:1. After the precipitant solution in step 2) is added dropwise, the reaction is continued to stir at a temperature of 15-40°C for 1-4h.

[0022] Furthermore, in step 3), the calcination temperature in the muffle furnace is 300-550° C., preferably 450-550° C., and the calcination time is 3.0-9.0 h, preferably 4.0-6.0 h.

[0023] Further, step 4) MeO x The mass ratio of the metal oxide to the AZE molecular sieve is 1:0.5-2, preferably 1:1-1.5, and the grinding time in the mortar is 0.2-1.0 h.

[0024] Furthermore, the auxiliary metal M is Zn, or Zn-Ga with a molar ratio of 3-4:1, and the total molar content of metal Zr and auxiliary metal M is 100%, wherein the content of Zr is 80.0-90.0 mol%, and the content of auxiliary metal M is 10.0-20.0 mol%.

[0025] The present invention also provides a dual-function MeO x / Application of AZE catalyst in catalytic hydrogenation conversion of carbon dioxide to synthesize high-density aviation fuel, the application method is:

[0026] S1: Prepare MeO x / AZE catalyst is pressed into granules on a powder tablet press, and the granulated catalyst is loaded into a fixed bed reactor, and a H2-N2 mixed gas with a H2 concentration of 5-30% is first introduced, and the temperature is raised to 300-500°C to reduce for 2.0-6.0h to activate the catalyst;

[0027] S2: using N2 as internal standard gas, preparing a mixed gas of CO2, H2 and N2 as a gas raw material; dissolving 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, acenaphthene and fluorene, and the alkane solvent is one or more of decahydronaphthalene, cyclohexane, octane and heptane;

[0028] S3: After the catalyst activation in step S1 is completed, gas phase reaction raw materials and liquid phase reaction raw materials are introduced, and then the reaction pressure is 2.0-6.0MPa, the reaction temperature is 250-500℃, and the gas hourly space velocity GHSV is 3000-48000h -1 , liquid hourly space velocity WHSV is 5-50h -1 The CO2 hydrogenation conversion reaction is carried out under the following conditions to obtain the product of CO2 hydrogenation coupling condensed aromatic hydrocarbons, which is the high-density aviation fuel.

[0029] Furthermore, in step S1, the H2 concentration of the H2-N2 mixed gas introduced during reduction is 10-20%, and the reduction temperature is 300-350°C.

[0030] Furthermore, in step S3, the reaction pressure is 3.0-4.0 MPa, and the reaction temperature is 300-400°C.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The prior art does not introduce condensed aromatics into the CO2 hydrogenation reaction, and the aviation fuel products obtained are C8-C16 chain alkanes and monocyclic aromatics such as alkylbenzenes, which are not high-density aviation fuel components. The present invention introduces condensed aromatics into the CO2 hydrogenation reaction, performs functional coupling reaction, and synthesizes alkyl-substituted condensed hydrocarbon compounds, thus overcoming the difficulty that high-density aviation fuel components cannot be synthesized by single CO2 hydrogenation, and enhancing the selectivity of alkyl polycyclic hydrocarbon products, which are high-density aviation fuel components with excellent performance.

[0033] 2. Dual-functional MeO of the present invention x The mechanism of CO2 hydrogenation coupling reaction promoted by AZE catalyst is that CO2 x Under the action of CO2, activated hydrogenation is performed to form methoxy active species, which then diffuse into AZE and react with polycyclic aromatic hydrocarbons under the action of acidic sites to form alkyl-substituted polycyclic aromatic hydrocarbons. The catalyst synthesized by the present invention exhibits excellent CO2 hydrogenation coupling performance and excellent hydrogenation coupling efficiency, promotes the conversion of CO2 and the coupling reaction with polycyclic aromatic hydrocarbons, and enhances the selectivity of high-density aviation fuel components.

[0034] 3. The reaction route for preparing high-density aviation fuel in the present invention is simple. x / AZE catalyst can catalyze the conversion in one step, and high-density aviation fuel components can be obtained without multi-step reactions.

[0035] 4. Dual-functional MeO of the present invention x When preparing the / AZE catalyst, MeOx metal oxide is first prepared by precipitation reaction and calcination, and then MeO x The metal oxide and AZE molecular sieve are ground in a mortar to make the metal oxide fully contact with the molecular sieve. The metal oxide will not block the pores of the AZE molecular sieve. Since the catalyst pore size has a relatively large impact on the reaction of CO2 hydrogenation coupled with polycyclic aromatic hydrocarbon conversion, the catalytic activity is maintained at a high level. In the existing conventional catalyst preparation method, metal Zr and M react with a precipitant and are directly precipitated on the AZE molecular sieve, then dried and calcined in a muffle furnace. Although the metal oxide and the molecular sieve are more closely combined, the metal oxide is easy to block the pores of the molecular sieve, affecting the diffusion of polycyclic aromatic hydrocarbons into the pores to contact the acidic sites, and the catalytic performance is deteriorated. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is the X-ray crystal diffraction pattern of the solid oxide prepared in Example 1-2;

[0037] Figure 2The pictures are of the combustion process of JP-10 fuel and JP-10 fuel mixed with different amounts of high-density aviation fuel synthesized by the present invention, (a) a fuel sample with a mixed amount of 10wt% of the high-density aviation fuel synthesized by the present invention, (b) a fuel sample with a mixed amount of 20wt% of the high-density aviation fuel synthesized by the present invention, and (c) JP-10 fuel. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0039] In the present invention, Hβ molecular sieve was purchased from Clariant Company, with a specific surface area of ​​562m 2 / g, pore diameter ~0.70nm, pore volume 0.4187cm 3 / g.

[0040] Example 1: Bifunctional Zn 0.20 Zr 0.80 Synthesis of O / Hβ Catalyst

[0041] Weigh 0.45g (1.5mmol) Zn(NO3)2·6H2O and 2.56g (6mmol) Zr(NO3)4·5H2O and dissolve them in anhydrous ethanol, ultrasonically treat for 0.5h, put them in a constant temperature water bath at 25℃, and stir at 800rpm, which is recorded as solution A. Weigh 1.44g oxalic acid and dissolve it in anhydrous ethanol, stir vigorously for 0.5h to dissolve evenly, which is recorded as solution B. Under the condition of magnetic stirring in a constant temperature water bath, use a microsyringe to add solution B to solution A at a rate of 2.5mL / min. After stirring for 2.0h, use centrifugation at 10000rpm to separate and collect the precipitated solid, and wash it with anhydrous ethanol 3 times. After drying the collected solid at 110℃ in an oven for 8h, calcine it at 500℃ in a muffle furnace for 6h to prepare Zn 0.20 Zr 0.80 O solid oxide, wherein the Zn content is 20 mol%. 0.5 g Zn 0.20 Zr 0.80 O was mixed with 0.5 g Hβ molecular sieve and ground in an agate mortar for 0.25 h. The ground powder was pressed into 60-80 mesh particles using a powder tablet press, i.e., the synthesized bifunctional Zn 0.20 Zr 0.80 O / Hβ catalyst.

[0042] Example 2: Bifunctional Zn 0.11 Zr 0.89 Synthesis of O / Hβ Catalyst

[0043] Weigh 0.45g (1.5mmol) Zn(NO3)2·6H2O and 5.15g (12mmol) Zr(NO3)4·5H2O and dissolve them in anhydrous ethanol, ultrasonically treat for 0.5h, put them in a constant temperature water bath at 25℃, and stir at 800rpm, which is recorded as solution A. Weigh 2.75g oxalic acid and dissolve it in anhydrous ethanol, stir vigorously for 0.5h to dissolve evenly, which is recorded as solution B. Under the condition of magnetic stirring in a constant temperature water bath, use a microsyringe to add solution B to solution A at a rate of 2.5mL / min. After stirring for 2.0h, use centrifugation at 10000rpm to separate and collect the precipitated solid, and wash it with anhydrous ethanol 3 times. After drying the collected solid at 110℃ in an oven for 8h, calcine it at 500℃ in a muffle furnace for 6h to prepare Zn 0.11 Zr 0.89 O solid oxide, wherein the Zn content is 11 mol%. 0.5 g Zn 0.11 Zr 0.89 O was mixed with 0.5 g Hβ molecular sieve and ground in an agate mortar for 0.25 h. The ground powder was pressed into 60-80 mesh particles using a powder tablet press, i.e., the synthesized bifunctional Zn 0.11 Zr 0.89 O / Hβ catalyst.

[0044] Figure 1 The X-ray crystal diffraction pattern of the solid oxide prepared in Example 1-2 is as follows: Figure 1 It can be seen that the solid oxide prepared by oxalic acid has a good tetragonal zirconia crystal phase (PDF#01-088-1007), and no characteristic diffraction peak of ZnO is observed, indicating that Zn is successfully doped into the crystal structure of zirconia to form a highly dispersed solid solution structure, which can effectively catalyze the CO2 hydrogenation coupling reaction.

[0045] Example 3: Bifunctional Zn 0.11 Ga 0.03 Zr 0.86 Synthesis of O / Hβ Catalyst

[0046] 0.25g (0.84mmol) Zn(NO3)2·6H2O, 0.06g (0.234mmol) Ga(NO3)3·xH2O and 2.87g (6.69mmol) Zr(NO3)4·5H2O were weighed and dissolved in anhydrous ethanol, ultrasonically treated for 0.5h, placed in a 25℃ constant temperature water bath, and stirred at 800rpm, which was recorded as solution A. 1.57g oxalic acid was weighed and dissolved in anhydrous ethanol, vigorously stirred for 0.5h to dissolve evenly, which was recorded as solution B. Under the condition of magnetic stirring in a constant temperature water bath, solution B was added dropwise to solution A at a speed of 2.5mL / min using a microsyringe, and after stirring for 2.0h, the precipitated solid was separated and collected by centrifugation at 10000rpm, and washed with anhydrous ethanol 3 times. The collected solid was dried in an oven at 110 °C for 8 h and then calcined in a muffle furnace at 500 °C for 6 h to prepare Zn 0.11 Ga 0.03 Zr 0.86 O solid oxide, wherein the content of Zn is 11mol%, and the content of Ga is 3mol%. 0.5g Zn 0.11 Ga 0.03 Zr 0.86 O was mixed with 0.5 g Hβ molecular sieve and ground in an agate mortar for 0.25 h. The ground powder was pressed into 60-80 mesh particles using a powder tablet press, i.e., the synthesized bifunctional Zn 0.11 Ga 0.03 Zr 0.86 O / Hβ catalyst.

[0047] Example 4: Preparation of high-density aviation fuel by CO2 hydrogenation based on functional coupling

[0048] The CO2 hydrogenation reaction was carried out using a stainless steel tubular fixed bed reactor with a quartz liner, using the following steps:

[0049] (1) A stainless steel tubular fixed bed reactor with a quartz lining is used for the CO2 hydrogenation catalytic reaction. Compared with the intermittent operation of a high-pressure reactor, a fixed bed reactor can perform a continuous reaction, which has obvious advantages;

[0050] (2) MeO prepared in Examples 1-3 x / AZE catalysts were pressed into 60-80 mesh particles on a powder tablet press;

[0051] (3) loading the granulated catalyst in step (2) into the quartz lining of a stainless steel reaction tube of a fixed bed reactor, fixing the catalyst particles in the middle of the reaction tube with quartz wool, and then installing it on the fixed bed reactor;

[0052] (4) Use nitrogen to adjust the fixed bed pressure to 5.0 MPa and perform a leak test. The pressure of the device does not drop significantly within 0.5 h, indicating that the device has good sealing performance.

[0053] (5) After the high-pressure nitrogen is exhausted, the nitrogen is replaced with a hydrogen-nitrogen mixed gas under normal pressure, the hydrogen flow rate is adjusted to 20 mL / min, the nitrogen flow rate is adjusted to 80 mL / min, and the temperature is raised to 350° C. to reduce for 2.5 h to activate the catalyst;

[0054] (6) After the catalyst activation is completed, the reaction pressure is adjusted to 4.0 MPa and the reaction temperature is 300-400° C. using a mixed gas (CO2:H2:N2=23:69:8, volume ratio). The liquid feed is a cyclohexane solution of polycyclic aromatic hydrocarbon naphthalene. The gas hourly space velocity (GHSV) during the hydrogenation coupling reaction is 6000 h -1 , liquid hourly space velocity (WHSV) is 9.5h -1 After the reaction reaches steady state, the liquid products after the reaction are collected, the gas products are detected online using a multi-channel gas chromatograph (Agilent 8890) with TCD and FID detectors, and the liquid products are analyzed offline using a single-channel chromatograph (Agilent 8890) with FID. There are three main ways for CO2 to be used in the reaction products: 1) coupling with polycyclic aromatic hydrocarbons to form high-density aviation fuel, 2) forming CO, 3) generating C1-C4 gaseous hydrocarbon small molecules, and 4) forming dimethyl ether.

[0055] Table 1.1 shows the performance data of catalytic CO2 hydrogenation coupling naphthalene to prepare high-density aviation fuel using a fixed bed reactor and the catalysts of Example 1-3. Reaction conditions: pressure 4.0 MPa, temperature 320-360°C, gas raw material composition volume ratio CO2:H2:N2=23:69:8 (N2 is internal standard gas), liquid feed is cyclohexane solution of polycyclic aromatic hydrocarbon naphthalene, gas raw material gas hourly space velocity (GHSV) is 6000h -1 , liquid hourly space velocity (WHSV) is 9.5h -1 . As the reaction temperature increases, the conversion rate of CO2 increases. Zn 0.20 Zr 0.80 O / Hβ and Zn 0.11 Zr 0.89 O / Hβ exhibits a very high CO2 conversion rate, which is further improved after further doping with Ga.

[0056] Table 1.1 Bifunctional MeO x / Hβ catalyst CO2 hydrogenation activity data

[0057]

[0058]

[0059] In addition, referring to the synthesis method of the catalyst in Example 1, the only difference is that the precipitant is replaced by an equal molar amount of ammonium carbonate instead of oxalic acid, and the other conditions remain unchanged, and Zn prepared by using ammonium carbonate is obtained. 0.20 Zr 0.80 O / Hβ catalyst. This catalyst was used for CO2 hydrogenation reaction under the same reaction conditions as in "Table 1.1" at a reaction temperature of 360°C. The reaction results are listed in Table 1.2.

[0060] Table 1.2 Effect of catalysts prepared with different precipitants on CO2 hydrogenation reaction

[0061]

[0062] Ammonium carbonate is also a commonly used precipitant in the literature, but MeO prepared with ammonium carbonate x The performance is not as good as that prepared by oxalic acid, because the number of active sites in the oxide prepared by ammonium carbonate is low, such as low oxygen vacancies, which are the main active sites for catalytic CO2 activation, leading to the deterioration of the CO2 hydrogenation performance of the catalyst. As shown in Table 1.2, the CO2 conversion rate of the catalyst prepared by using ammonium carbonate precipitant is 17.1%, which is lower than 20.5% of oxalic acid.

[0063] Table 2 shows the performance data of the hydrogenation coupling of naphthalene to prepare high-density aviation fuel using a fixed bed reactor in Examples 1-3. Reaction conditions: pressure 4.0 MPa, temperature 320-360°C, gas raw material composition CO2:H2:N2=23:69:8, gas hourly space velocity (GHSV) 6000h -1 The liquid feed is a cyclohexane solution of polycyclic aromatic hydrocarbon naphthalene, and the liquid hourly space velocity (WHSV) is 9.5h -1 As the reaction temperature increases, the hydrogenation coupling selectivity of the bifunctional catalyst decreases. This is mainly because the increase in reaction temperature promotes the reverse water gas reaction and enhances the selectivity of CO. However, the prepared bifunctional MeO x The / Hβ catalyst showed an excellent hydrogenation coupling efficiency, indicating that the CO2 hydrogenation and condensed aromatic hydrocarbon alkylation reactions were successfully coupled, which promoted the conversion of CO2, enhanced the selectivity of alkyl polycyclic hydrocarbon products, and obtained a high-density aviation fuel component with excellent performance.

[0064] Table 2 Bifunctional MeO x Hydrogenation coupling performance data of / Hβ catalyst

[0065]

[0066] Table 3 shows the selectivity data of the liquid phase product of high-density aviation fuel prepared by catalytic hydrogenation of CO2 coupled with naphthalene in Example 1-2 using a fixed bed reactor. Reaction conditions: pressure 4.0 MPa, temperature 320-360°C, gas raw material composition CO2:H2:N2=23:69:8, gas hourly space velocity (GHSV) 6000h -1 The liquid feed is a cyclohexane solution of polycyclic aromatic hydrocarbon naphthalene, and the liquid hourly space velocity (WHSV) is 9.5h -1 It can be seen that the liquid products are mainly 2-methylnaphthalene and 1-methylnaphthalene, followed by dimethylnaphthalene, and a small amount of ethylnaphthalene and trimethylnaphthalene. All of them are good polyalkyl-substituted naphthalene compounds and are high-density aviation fuel components with excellent performance.

[0067] Table 3 Bifunctional MeO x Liquid-phase product selectivity of CO2 hydrogenation coupling catalyzed by / Hβ catalyst

[0068]

[0069] Table 4 shows the density data of the prepared high-density aviation fuel (i.e., the liquid product obtained in Experiment 3 in Table 1.1 and Table 2) after being mixed with JP-10. The density of the currently widely used U.S. military aviation fuel JP-10 is 0.936 g / mL. After being mixed with the high-density aviation fuel component synthesized by the present invention, the density is significantly improved. When the doping amount of the "high-density aviation fuel component synthesized by the present invention" is 20wt%, the density is increased to 0.949 g / mL, indicating the excellent performance of the high-density aviation fuel prepared by the present invention. In addition, when the doping amount is increased from 0 to 20wt%, the dynamic viscosity of the fuel increases from 3.10 mm 2 / s reduced to 2.76mm 2 / s, indicating that the flow properties of the fuel have been significantly improved.

[0070] Table 4 Fuel density data after mixing synthetic high-density aviation fuel and JP-10

[0071] Fuel samples Doping amount (wt%) Density(g / mL) <![CDATA[Viscosity (mm 2 / s)]]> 1 0 0.936 3.10 2 10 0.942 2.89 3 20 0.949 2.76

[0072] Figure 2 The following is a picture of the combustion process of a fuel sample with a doping amount of 20wt% and JP-10. The ignition delay time is defined as the time difference between the fuel droplet contacting the flat surface and the appearance of the spark, which can be used to characterize the fuel performance. Figure 2 (a) It can be seen that the ignition delay time of the fuel sample with a doping amount of 10wt% is 2548ms. Figure 2 (b) The ignition delay time of the fuel sample with a doping amount of 20wt% is 2276ms. As the doping amount increases, the ignition delay time of the fuel is significantly shortened, which is better than Figure 2The ignition delay time of JP-10 in (c) is 2752ms. The ignition delay time represents the combustion performance of the synthesized fuel. The shorter the ignition time, the more conducive it is to ignite the fuel within a short period of time, fully release the energy of the fuel, and the better the fuel performance.

[0073] It is proved that the ignition performance of JP-10 is enhanced after mixing and blending. This is because the aromatic ring structure in the alkyl condensed aromatic hydrocarbons has abundant π electrons and is easy to generate active free radicals under high-temperature combustion conditions. These free radicals can accelerate the propagation of the chain reaction during the combustion process, provide additional reaction paths, promote the chain reaction during the combustion process, and enhance the combustion rate; the alkyl substituent reduces the symmetry of the molecule, making its combustion process more efficient. The synergistic effect of the aromatic ring and the alkyl chain provides multiple reaction paths for the oxidation reaction. This complex reaction network reduces the combustion activation energy and improves the combustion rate of JP-10. Shortening the ignition delay time can reduce the combustion start time, improve the combustion efficiency, avoid combustion chamber instability or efficiency loss, reduce the risk of pressure fluctuations caused by incomplete combustion in high-pressure and high-temperature combustion chambers, and improve combustion stability. This shows that the alkyl polycyclic hydrocarbon compounds synthesized by CO2 hydrogenation coupled to condensed aromatic hydrocarbon alkylation in the present invention are high-density aviation fuel components with good performance.

Claims

1. A bifunctional MeO x / A method for synthesizing an AZE catalyst, characterized in that The MeO x It is a composite metal oxide of metal Zr and auxiliary metal M, wherein the total molar content of metal Zr and auxiliary metal M is 100%, wherein the content of Zr is 75.0-95.0 mol%, and the content of auxiliary metal M is 5.0-25.0 mol%; The additive metal M is one or more of Zn, Ga, Ce, La, and In; AZE is an acidic molecular sieve; The synthesis method of the catalyst comprises the following steps: 1) Dissolve the Zr source and the M source in a solvent, disperse them uniformly by ultrasonication, and prepare a mixed metal solution; 2) adding the precipitant solution to the mixed metal solution in step 1) and stirring the reaction sufficiently to achieve complete precipitation; 3) The precipitate obtained in step 2) is collected by centrifugation, dried, and calcined in a muffle furnace to obtain MeO x Metal oxides; 4) Add MeO x The metal oxide and AZE molecular sieve are ground in a mortar to ensure that the metal oxide and the molecular sieve are in full contact. That is, bifunctional MeO x / AZE catalyst.

2. A bifunctional MeO as claimed in claim 1 x / A method for synthesizing an AZE catalyst, characterized in that In step 1), the solvent is anhydrous ethanol.

3. A bifunctional MeO as claimed in claim 1 x / A method for synthesizing an AZE catalyst, characterized in that In step 2), the precipitant is oxalic acid, and the ratio of the molar amount of oxalic acid to the total molar amount of metal Zr and auxiliary metal M is 2-3:

1. After the precipitant solution in step 2) is added dropwise, the reaction is continued to stir at a temperature of 15-40°C for 1-4h.

4. A bifunctional MeO as claimed in claim 1 x / A method for synthesizing an AZE catalyst, characterized in that Step 3) The calcination temperature in the muffle furnace is 300-550° C., preferably 450-550° C., and the calcination time is 3.0-9.0 h, preferably 4.0-6.0 h.

5. A bifunctional MeO as claimed in claim 1 x / A method for synthesizing an AZE catalyst, characterized in that Step 4) MeO x The mass ratio of the metal oxide to the AZE molecular sieve is 1:0.5-2, preferably 1:1-1.5, and the grinding time in the mortar is 0.2-1.0 h.

6. A bifunctional MeO as claimed in claim 1 x / A method for synthesizing an AZE catalyst, characterized in that The auxiliary metal M is Zn, or Zn-Ga with a molar ratio of 3-4:

1. Taking the total molar content of metal Zr and auxiliary metal M as 100%, the content of Zr is 80.0-90.0 mol%, and the content of auxiliary metal M is 10.0-20.0 mol%.

7. A bifunctional MeO synthesized by the method according to any one of claims 1 to 6 x / Application of AZE catalyst in catalytic carbon dioxide hydrogenation conversion to synthesize high-density aviation fuel.

8. The use according to claim 7, characterized in that The application method is: S1: Prepare MeO x / AZE catalyst is pressed into granules on a powder tablet press, and the granulated catalyst is loaded into a fixed bed reactor, and a H2-N2 mixed gas with a H2 concentration of 5-30% is first introduced, and the temperature is raised to 300-500°C for reduction for 2.0-6.0h to activate the catalyst; S2: using N2 as internal standard gas, preparing a mixed gas of CO2, H2 and N2 as a gas raw material; dissolving 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, acenaphthene and fluorene, and the alkane solvent is one or more of decahydronaphthalene, cyclohexane, octane and heptane; S3: After the catalyst activation in step S1 is completed, gas phase reaction raw materials and liquid phase reaction raw materials are introduced, and then the reaction pressure is 2.0-6.0MPa, the reaction temperature is 250-500℃, and the gas hourly space velocity GHSV is 3000-48000h -1 , liquid hourly space velocity WHSV is 5-50h -1 The CO2 hydrogenation conversion reaction is carried out under the following conditions to obtain the product of CO2 hydrogenation coupling condensed ring aromatics, which is the high-density aviation fuel.

9. The use according to claim 8, characterized in that In step S1, the H2 concentration of the H2-N2 mixed gas introduced during reduction is 10-20%, and the reduction temperature is 300-350°C.

10. The use according to claim 8, characterized in that In step S3, the reaction pressure is 3.0-4.0 MPa, and the reaction temperature is 300-400°C.

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