Synthesis of bifunctional meox / aze catalyst and its application in the synthesis of high-density aviation fuel by co2 hydrogenation

Abstract

The application discloses a synthesis method of a bifunctional MeO x / AZE catalyst and application of the catalyst in catalyzing CO2 hydrogenation to synthesize high-density aviation fuel, wherein MeO x is a composite metal oxide of Zr and an 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; and AZE is an acid molecular sieve. The catalyst synthesized by the application has excellent CO2 hydrogenation coupling performance. In the CO2 hydrogenation reaction, a condensed ring aromatic hydrocarbon is introduced to perform a functional coupling reaction, the conversion of CO2 is promoted, and the coupling reaction with the condensed ring aromatic hydrocarbon is performed, so that an alkyl-substituted condensed ring hydrocarbon compound is synthesized. The difficulty that single CO2 hydrogenation cannot synthesize a high-density aviation fuel component is overcome, and the selectivity of the high-density aviation fuel component alkyl polycyclic hydrocarbon product with excellent performance is strengthened.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of organic catalysis synthesis, and particularly relates to a synthesis method of a bifunctional MeO x / AZE catalyst and application of the catalyst in synthesis of high-density aviation fuel from CO2 hydrogenation. BACKGROUND

[0002] Liquid hydrocarbon fuel is the power source of aerospace vehicles and missile weapon systems, and is the key to determining the speed, range and load of the aircraft. The development of modern supersonic aircraft also puts forward higher requirements for the density (p>0.85 g / mL) of aviation fuel. Compared with conventional aviation fuel (such as RP-3), high-density aviation fuel has higher density, volumetric heat value and thermal oxidation stability, which can greatly improve the range of missiles, the flight distance and load of aircraft in a limited fuel tank volume. Developing green and sustainable high-density aviation fuel has become an important technical path to realize the green and rapid development of the aviation industry and the "double carbon" goal.

[0003] Carbon dioxide (CO2) is a rich, readily available, non-toxic and renewable carbon resource. Through coupling with green hydrogen, it is converted into alkyl polycyclic hydrocarbon high-density aviation fuel, which is an important way to realize the green and sustainable development of the aviation industry. However, due to the chemical inertness of CO2, the complexity of hydrogenation kinetics and the high carbon-carbon bond coupling energy barrier, C1 compounds such as CO and CH4 are easily formed, making it very difficult to synthesize alkyl polycyclic hydrocarbon high-density aviation fuel (C8-C 16 ).

[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, and the selectivity of C8-C 16 chain hydrocarbons in the product was as high as 47.8%, but the density was low (p<0.78 g / mL), which could not be used as high-density aviation fuel. Tsinghua University (ACS Catalysis, 2022, 12(3): 2023-2033) used a nano ZnCr2O4 / Sbx-H-ZSM-5 catalyst to synthesize C8-C 12 monocyclic aromatic compounds from CO2 hydrogenation, which can be used as aromatic components of aviation fuel, but the selectivity of high-density aviation fuel components such as polycyclic hydrocarbons in the hydrogenation product is not high.

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

[0006] Polycyclic aromatic hydrocarbons are the main components of heavy oil and coal tar. With the depletion of fossil energy and the improvement of coal liquefaction capacity in China, the production of heavy oil and coal tar is also increasing year by year. However, due to the low reactivity of polycyclic aromatic hydrocarbons caused by high resonance energy and steric hindrance, the resource utilization of polycyclic aromatic hydrocarbons has been a difficult problem in refining. However, polycyclic aromatic hydrocarbons have a multi-ring structure and high energy density. In the early stage, the inventors synthesized high-density aviation fuel components such as decalin and perhydrophenanthrene by deeply hydrogenating and saturating polycyclic aromatic hydrocarbons such as naphthalene and phenanthrene, which showed better density and volumetric heat value than the US military high-density fuel JP-10. However, saturated polycyclic aromatic hydrocarbons lack alkyl substituents, and their viscosity and low-temperature flowability are poor (CN113368891A, CN115197743A).

[0007] The introduction of alkyl substituents to 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 saturated by hydrogenation, 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 also 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, etc. Moreover, polycyclic aromatic hydrocarbons can also be obtained from biomass, and at this time 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 path for synthesizing high-density aviation fuel components with excellent performance by CO2 hydrogenation is developed. The MeO x / AZE bifunctional metal oxide-molecular sieve catalyst is synthesized by a coprecipitation method, and CO2 hydrogenation reaction is carried out under a polycyclic aromatic hydrocarbon atmosphere. The CO2 hydrogenation is coupled with polycyclic aromatic hydrocarbon alkylation to synthesize high-density aviation fuel components with excellent performance, i.e. alkyl polycyclic hydrocarbons, with high selectivity. The catalyst shows 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 having broad application prospects. SUMMARY

[0009] In view of the above technical problems existing in the prior art, the purpose of the present application is to provide a synthesis method of a bifunctional MeO x / AZE catalyst and its application in catalyzing CO2 hydrogenation to synthesize high-density aviation fuel.

[0010] The technical solutions adopted by the present application are as follows:

[0011] A bifunctional MeO xThe synthesis method of the / AZE catalyst, the MeO x is a complex metal oxide of metal Zr and auxiliary metal M, with the total mole content of both metal Zr and auxiliary metal M being 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 auxiliary metal M is one or several of Zn, Ga, Ce, La, and In;

[0013] The AZE is an acidic molecular sieve;

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

[0015] 1) Dissolving a Zr source and an M source together in a solvent, uniformly dispersing by ultrasonic, and preparing a mixed metal solution;

[0016] 2) Adding a precipitant solution to the mixed metal solution of step 1) dropwise, fully stirring and reacting to make the precipitation complete;

[0017] 3) Centrifuging and collecting the precipitate obtained in step 2), drying, and calcining in a muffle furnace to obtain the MeO x metal oxide;

[0018] 4) Grinding the MeO x metal oxide and the AZE molecular sieve in a mortar to make the metal oxide and the molecular sieve fully contact,

[0019] to obtain the bifunctional MeO x / AZE catalyst.

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

[0021] Further, in step 2), the precipitant is oxalic acid, and the ratio of the mole amount of oxalic acid to the total mole amount of metal Zr and auxiliary metal M is 2-3:1. After the addition of the precipitant solution in step 2) is completed, the stirring and reaction are continued at a temperature of 15-40°C for 1-4h.

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

[0023] Further, in step 4), the mass ratio of the MeO x 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 0.2-1.0h.

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

[0025] The application also provides a bifunctional MeO x / AZE catalyst in the application of catalyzing the synthesis of high-density aviation fuel from carbon dioxide and hydrogen, and the application method is:

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

[0027] S2: N2 is used as an internal standard gas, and a mixed gas of CO2, H2 and N2 is prepared as a gaseous raw material; and polycyclic aromatic hydrocarbons are dissolved 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 decalin, cyclohexane, octane and heptane;

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

[0029] Further, 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 DEG C.

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

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

[0032] 1. The prior art does not introduce condensed ring aromatic hydrocarbons in the CO2 hydrogenation reaction, and the obtained aviation fuel product is C8-C16 paraffin and monocyclic aromatic hydrocarbons such as alkylbenzene, which is not a high-density aviation fuel component. The present application introduces condensed ring aromatic hydrocarbons in the CO2 hydrogenation reaction, and performs a functional coupling reaction to synthesize alkyl-substituted condensed ring hydrocarbon compounds, overcoming the difficulty of synthesizing high-density aviation fuel components by single CO2 hydrogenation, and strengthening the selectivity of high-density aviation fuel component alkyl polycyclic hydrocarbon products with excellent performance.

[0033] 2. The bifunctional MeO x / AZE catalyst promotes the CO2 hydrogenation coupling reaction mechanism, CO2 is activated and hydrogenated under the action of MeO x to form a methoxy active species, which then diffuses into AZE to undergo alkylation with condensed ring aromatic hydrocarbons under the action of the acid site to form alkyl-substituted condensed ring aromatic hydrocarbons. The synthesized catalyst of the present application exhibits excellent CO2 hydrogenation coupling performance, has excellent hydrogenation coupling efficiency, promotes the conversion of CO2 and coupling reaction with condensed ring aromatic hydrocarbons, and strengthens the selectivity of high-density aviation fuel components.

[0034] 3. The reaction route for preparing high-density aviation fuel of the present application is simple, and the bifunctional MeO x / AZE catalyst is catalytically converted in one step, without the need for multi-step reactions, to obtain high-density aviation fuel components.

[0035] 4. The bifunctional MeO x / AZE catalyst of the present application is prepared by first preparing MeOx metal oxide through a precipitation reaction and calcination, and then grinding MeO x metal oxide and AZE molecular sieve in a mortar to ensure sufficient contact between the metal oxide and the molecular sieve. The metal oxide does not block the pores of the AZE molecular sieve, and since the catalyst pore size has a greater impact on the conversion of condensed ring aromatic hydrocarbons by CO2 hydrogenation coupling, it maintains high catalytic activity. However, in the conventional catalyst preparation method, metal Zr, M is directly precipitated on the AZE molecular sieve through a precipitant reaction, then dried, and calcined in a muffle furnace. Although the intimacy of the combination of the metal oxide and the molecular sieve is higher, the metal oxide easily blocks the pores of the molecular sieve, affecting the diffusion of condensed ring aromatic hydrocarbons into the pores to contact the acid sites, and the catalytic performance is poor. BRIEF DESCRIPTION OF DRAWINGS

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

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

[0038] The application will be further described in conjunction with specific examples, but the scope of protection of the application is not limited thereto.

[0039] In the embodiments of the application, the Hβ molecular sieve is purchased from Clariant Company, and has a specific surface area of 562m 2 / g, a pore size of ~0.70nm, and a pore volume of 0.4187cm 3 / g.

[0040] Example 1: Synthesis of bifunctional Zn 0.20 Zr 0.80 O / Hβ catalyst

[0041] 0.45g (1.5mmol) of Zn(NO3)2·6H2O and 2.56g (6mmol) of Zr(NO3)4·5H2O were weighed and dissolved in anhydrous ethanol, ultrasonically treated for 0.5h, and placed in a 25℃ constant-temperature water bath, and stirred at a speed of 800rpm, and marked as solution A. 1.44g of oxalic acid was weighed and dissolved in anhydrous ethanol, and stirred vigorously for 0.5h to dissolve uniformly, and marked as solution B. Under the condition of constant-temperature water bath magnetic stirring, solution B was added dropwise to solution A at a speed of 2.5mL / min using a microsyringe, and stirring was continued for 2.0h, and the precipitated solid was separated and collected by centrifugation at 10000rpm, and washed with anhydrous ethanol for 3 times. The collected solid was dried in an oven at 110℃ for 8h, and then calcined in a muffle furnace at 500℃ for 6h, to prepare Zn 0.20 Zr 0.80 O solid oxide, wherein the content of Zn is 20mol%. 0.5g of Zn 0.20 Zr 0.80 O was mixed with 0.5g of Hβ molecular sieve, and ground in an agate mortar for 0.25h. The ground powder was pressed into particles of 60-80 mesh using a powder tablet press, to synthesize the bifunctional Zn 0.20 Zr 0.80 O / Hβ catalyst.

[0042] Example 2: Synthesis of bifunctional Zn 0.11 Zr 0.89 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 them at 800rpm, which is recorded as solution A. Weigh 2.75g oxalic acid and dissolve it in anhydrous ethanol, stir vigorously for 0.5h and 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 continuing to stir 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, calcined it at 500℃ in a muffle furnace for 6h to prepare Zn 0.11 Zr 0.89 O solid oxide, wherein the content of Zn 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, which was 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, forming 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] Zn(NO3)2.6H2O, 0.06 g (0.234 mmol) Ga(NO3)3.xH2O and 2.87 g (6.69 mmol) Zr(NO3)4.5H2O were dissolved in absolute ethanol, ultrasonic treated for 0.5 h, put into a constant temperature water bath at 25 °C and stirred at a speed of 800 rpm, denoted as solution A. 1.57 g of oxalic acid was dissolved in absolute ethanol, and stirred vigorously for 0.5 h to dissolve uniformly, denoted as solution B. Under the condition of constant temperature water bath magnetic stirring, solution B was added to solution A at a speed of 2.5 mL / min using a microsyringe, and stirring was continued for 2.0 h. The precipitated solid was separated by centrifugation at 10,000 rpm, and washed with absolute ethanol for 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 11 mol%, and the content of Ga is 3 mol%. 0.5 g of Zn 0.11 Ga 0.03 Zr 0.86 O was mixed with 0.5 g of Hβ molecular sieve, and ground in an agate mortar for 0.25 h. The ground powder was pressed into particles of 60-80 mesh using a powder tablet press, to synthesize a 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] A stainless steel tubular fixed bed reactor with a quartz lining was used for the CO2 hydrogenation reaction, using the following steps:

[0049] (1) The CO2 hydrogenation catalytic reaction was carried out in a stainless steel tubular fixed bed reactor with a quartz lining, which has obvious advantages over the batch operation of high-pressure autoclaves, as it can perform continuous reaction;

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

[0051] (3) The catalyst particles prepared in step (2) were loaded into the quartz lining of the stainless steel reaction tube of the fixed bed reactor, the catalyst particles were fixed in the middle of the reaction tube using quartz wool, and then installed on the fixed bed reactor;

[0052] (4) The pressure of the fixed bed was adjusted to 5.0 MPa using nitrogen, and leakage was detected. The pressure of the device did not decrease significantly within 0.5 h, indicating that the device was well sealed.

[0053] (5) After emptying the high-pressure nitrogen, the nitrogen was replaced with hydrogen and nitrogen mixture at atmospheric pressure. The hydrogen flow was adjusted to 20 mL / min, and the nitrogen flow was adjusted to 80 mL / min. The catalyst was activated by reducing at 350°C for 2.5 h;

[0054] (6) After the catalyst activation was completed, the reaction pressure was adjusted to 4.0 MPa using a mixed gas (CO2:H2:N2=23:69:8, volume ratio). The reaction temperature was 300-400°C. The liquid feed was a naphthalene cyclohexane solution. The gas hourly space velocity (GHSV) during the hydrogenation coupling reaction was 6000 h -1 , and the liquid hourly space velocity (WHSV) was 9.5 h -1 . After the reaction reached steady state, the liquid product after the reaction was collected. The gas phase product was detected online using a multi-channel gas chromatograph (Agilent 8890) with TCD and FID detectors. The liquid product was analyzed offline using a single-channel chromatograph (Agilent 8890) with FID. The main utilization pathways of CO2 in the reaction product were as follows: 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 CO2 hydrogenation performance data of the catalysts of Examples 1-3 for preparing high-density aviation fuel by CO2 hydrogenation coupling with naphthalene using a fixed bed reactor. The reaction conditions were as follows: pressure 4.0 MPa, temperature 320-360°C, gas feed composition volume ratio CO2:H2:N2=23:69:8 (N2 as internal standard gas), liquid feed polycyclic aromatic hydrocarbon naphthalene cyclohexane solution, gas feed gas hourly space velocity (GHSV) 6000 h -1 , and liquid hourly space velocity (WHSV) 9.5 h -1 . As the reaction temperature increased, the CO2 conversion rate increased. Zn 0.20 Zr 0.80 O / Hβ and Zn 0.11 Zr 0.89 O / Hβ showed very high CO2 conversion rate, and further doping with Ga further improved the CO2 conversion rate.

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

[0057]

[0058]

[0059] According to the synthesis method of the catalyst of Example 1, the difference is only that the precipitant is replaced by "ammonium carbonate" with the same molar amount, and the other conditions remain unchanged, to obtain ZnO / Hβ catalyst prepared by "ammonium carbonate". 0.20 Zr 0.80 O / Hβ catalyst. The catalyst was subjected to CO2 hydrogenation reaction under the same reaction conditions as the reaction temperature 360°C in "Table 1.1", and the reaction results are listed in Table 1.2.

[0060] Table 1.2 Influence of catalyst prepared by different precipitants on CO2 hydrogenation reaction

[0061]

[0062] Ammonium carbonate is also a commonly used precipitant in the literature, but the MeO x prepared by ammonium carbonate has poorer performance than that prepared by oxalic acid, because the number of active sites in the oxide prepared by ammonium carbonate is lower, such as the content of oxygen vacancies, and oxygen vacancies are the main active sites for catalyzing CO2 activation, which further leads to the deterioration of the performance of the catalyst for CO2 hydrogenation. As shown in Table 1.2, the CO2 conversion rate of the catalyst prepared by using ammonium carbonate as the precipitant is 17.1%, which is lower than 20.5% of oxalic acid.

[0063] Table 2 is the hydrogenation coupling performance data of Examples 1-3 for catalyzing CO2 hydrogenation to prepare high-density aviation fuel coupled with naphthalene. 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) 6000 h -1 , and the liquid phase feed is a cyclohexane solution of polycyclic aromatic hydrocarbon naphthalene, and the liquid hourly space velocity (WHSV) is 9.5 h -1 . With the increase of reaction temperature, the hydrogenation coupling selectivity of the bifunctional catalyst decreases, which is mainly because the increase of reaction temperature promotes the occurrence of reverse water gas shift reaction, and strengthens the selectivity of CO. However, the bifunctional MeO x / Hβ catalyst prepared shows excellent hydrogenation coupling efficiency, indicating that CO2 hydrogenation and alkylation of polycyclic aromatic hydrocarbon are successfully coupled, which promotes the conversion of CO2 and enhances the selectivity of alkylation polycyclic hydrocarbon product, and obtains high-density aviation fuel component with excellent performance.

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

[0065]

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

[0067] Table 3 dual functional MeO x / Hβ catalyst catalyzed CO2 hydrogenation coupled liquid phase product selectivity

[0068]

[0069] Table 4 is the density data of the high-density aviation fuel prepared (i.e. the liquid product obtained in experiment 3 in Table 1.1, Table 2) mixed with JP-10. The density of the widely used US military aviation fuel JP-10 is 0.936 g / mL. The density of the mixed fuel with the high-density aviation fuel component synthesized in the present application is significantly improved. When the doping amount of the "high-density aviation fuel component synthesized in the present application" is 20 wt%, the density is increased to 0.949 g / mL, indicating that the high-density aviation fuel prepared in the present application has excellent performance. In addition, when the doping amount increases from 0 to 20 wt%, the dynamic viscosity of the fuel decreases from 3.10 mm 2 / s to 2.76 mm 2 / s, indicating that the flow performance of the fuel has been significantly improved.

[0070] Table 4 density data of the mixed fuel of the synthesized high-density aviation fuel and JP-10

[0071] Fuel sample Doping amount (wt%) Density (g / mL) 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 pictures of the combustion process of the fuel sample with a doping amount of 20 wt% and JP-10. The ignition delay time is defined as the time difference from the time when the fuel droplet contacts the flat surface to the time when the spark appears, which can be used to characterize the fuel performance of the fuel. From Figure 2 (a) it can be seen that the ignition delay time of the fuel sample with a doping amount of 10 wt% is 2548 ms, Figure 2 (b) the ignition delay time of the fuel sample with a doping amount of 20 wt% is 2276 ms, and as the doping amount increases, the ignition delay time of the fuel is significantly shortened, which is better than Figure 2(c) The ignition delay time of JP-10 is 2752 ms, which represents the combustion performance of the synthesized fuel. The shorter the ignition time, the more beneficial it is to ignite the fuel within a certain 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, because the aromatic ring structure in alkyl condensed ring aromatic hydrocarbon has rich π electrons, which is easy to generate active free radicals under high temperature combustion conditions. These free radicals can accelerate the propagation of chain reaction in the combustion process, provide additional reaction path, promote the chain reaction in the combustion process, and enhance the combustion rate; the alkyl substituent group reduces the symmetry of the molecule, making the combustion process more efficient, and the synergistic effect of aromatic ring and alkyl chain provides multiple reaction paths for 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-up time, improve the combustion efficiency, avoid the instability or efficiency loss of the combustion chamber, reduce the risk of pressure fluctuation caused by incomplete combustion in the high-pressure and high-temperature combustion chamber, and improve the combustion stability. This shows that the alkyl polycyclic hydrocarbon compound synthesized by CO2 hydrogenation coupling alkylation of condensed ring aromatic hydrocarbon in the present application is a high-density aviation fuel component with good performance.

Claims

1. A bifunctional MeO catalyst for catalytic carbon dioxide hydrogenation to synthesize high-density aviation fuel 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 auxiliary metal M is one or both of Zn and Ga; 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 a precipitant solution, wherein the precipitant is oxalic acid, to the mixed metal solution in step 1) and stirring the reaction thoroughly to allow complete precipitation; 3) The precipitate obtained in step 2) was collected by centrifugation, dried, and calcined in a muffle furnace to obtain MeO x Metal oxides; 4) MeO x Grind the metal oxide and AZE molecular sieve in a mortar to ensure full contact between the metal oxide and the molecular sieve. That is, bifunctional MeO was prepared x / AZE catalyst.

2. A bifunctional MeO for catalytic carbon dioxide hydrogenation conversion to synthesize high-density aviation fuel according to 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 for catalytic carbon dioxide hydrogenation conversion to synthesize high-density aviation fuel according to claim 1 x / A method for synthesizing an AZE catalyst, characterized in that In step 2), 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 dropwise addition of the precipitant solution in step 2), the reaction is continued with stirring at a temperature of 15-40° C. for 1-4 hours.

4. A bifunctional MeO for catalytic carbon dioxide hydrogenation conversion to synthesize high-density aviation fuel according to claim 1 x / A method for synthesizing an AZE catalyst, characterized in that Step 3) calcining in a muffle furnace at a temperature of 300-550° C. for 3.0-9.0 h.

5. A bifunctional MeO for catalytic carbon dioxide hydrogenation conversion to synthesize high-density aviation fuel as claimed in claim 4 x / A method for synthesizing an AZE catalyst, characterized in that Step 3) calcining in a muffle furnace at a temperature of 450-550° C. for 4.0-6.0 h.

6. A bifunctional MeO for catalytic carbon dioxide hydrogenation conversion to synthesize high-density aviation fuel according to 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, and the grinding time in the mortar is 0.2-1.0 h.

7. A bifunctional MeO for catalytic carbon dioxide hydrogenation conversion to synthesize high-density aviation fuel according to claim 6 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 1:1-1.

5.

8. A bifunctional MeO for catalytic carbon dioxide hydrogenation conversion to synthesize high-density aviation fuel 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. Based on the total molar content of metal Zr and auxiliary metal M being 100%, the content of Zr is 80.0-90.0 mol%, and the content of auxiliary metal M is 10.0-20.0 mol%.

9. A bifunctional MeO synthesized by the method according to any one of claims 1 to 8 x / Application of AZE catalyst in catalytic carbon dioxide hydrogenation to synthesize high-density aviation fuel.

10. The use according to claim 9, characterized in that The application method is: S1: Prepare MeO x / AZE catalyst is pressed into granules on a powder tablet press. The granulated catalyst is loaded into a fixed bed reactor. A H2-N2 mixture with a H2 concentration of 5-30% is first introduced, and the temperature is raised to 300-500°C for reduction for 2.0-6.0 hours 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 condensed ring aromatic hydrocarbons in an alkane solvent to prepare a liquid phase reaction raw material, wherein the condensed ring 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, the gas phase reaction raw materials and the 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 in the reaction is 3000-48000h -1 , liquid hourly space velocity WHSV is 5-50h -1 The CO2 hydrogenation reaction is carried out under the following conditions to obtain the product of CO2 hydrogenation coupling with condensed ring aromatics, which is the high-density aviation fuel.

11. The use according to claim 10, 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.

12. The use according to claim 10, 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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