A chain-substituted tricyclic fused cycloalkane compound, a preparation method thereof, and an application thereof

Abstract

The present invention discloses a molecular of chain-substituted tricyclic fused cycloalkane compounds, having the following structure: wherein, n = 1, 2 or 3; R1, R2, R3, R4 are each H or -CH3 or -CH2CH3. The present invention also discloses a heterogeneous catalytic preparation method of the chain-substituted tricyclic fused cycloalkane compounds and their use as liquid propellants for aerospace vehicles. The chain-substituted fused cycloalkane fuels of the present invention have excellent properties of high density, high calorific value, low freezing point and high thermal stability, and the preparation method has mild reaction conditions and high selectivity of the target product.

Description

Technical Field:

[0001] The present invention belongs to the technical field of liquid fuel propellants, and particularly relates to a chain-substituted tricyclic fused cycloalkane compound, a preparation method thereof, and an application thereof. Background Art:

[0002] High-energy density liquid fuels have the characteristics of high density and large volumetric calorific value. Without increasing the fuel tank volume, they can significantly improve the payload, range, and penetration ability of aircraft.

[0003] Traditional aerospace fuels mainly come from the fractionation of petroleum, and their main components are linear alkanes, with a density usually lower than 0.80 g / cm 3 , which cannot meet the high-performance requirements of advanced jet fuels. Fossil energy is a non-renewable resource. In recent years, the international community has paid more and more attention to the energy crisis and carbon emission issues. Using renewable biomass resources to replace traditional fossil energy helps to achieve the dual-carbon goal earlier. Currently, the hydrocarbon fuels prepared from renewable biomass are mainly divided into linear alkanes, monocyclic alkanes, bicyclic alkanes, tricyclic alkanes, and polycyclic alkanes in terms of molecular structure. The densities of the first four compounds are approximately 0.78, 0.8, 0.85, and 0.9 g / cm 3 respectively. It can be seen that the density of hydrocarbons increases with the increase in the number of ring units in their molecular structure. In addition, the current synthesis strategies for biomass fuels are mainly through hydroxyalkylation / alkylation reactions, aldol condensation reactions, olefin polymerization reactions, cyclohexanone coupling reactions, and Michael addition reactions, etc. These synthesis processes are all limited to carbon chain growth, only increasing the carbon number in the molecular structure, but lacking the construction of new ring units. Therefore, the fuel density highly depends on the characteristics of the cyclic raw materials themselves and it is difficult to significantly improve the fuel density.

[0004] Therefore, the key to synthesizing high-performance biomass hydrocarbon fuels is to develop new reactions to construct polycyclic structures to further increase the fuel density. Summary of the Invention:

[0005] To solve the technical problems existing in the above background art, the first aspect of the present invention provides a chain-substituted tricyclic fused cycloalkane compound, and the fuel has the following molecular structure:

[0006]

[0007] Wherein, n = 1, 2 or 3; R1, R2, R3, and R4 are each H or -CH3 or -CH2CH3.

[0008] Furthermore, the density of the compound is greater than 0.910 g / cm 3 , the freezing point is not higher than -50 °C, and the net calorific value by mass is not lower than 42.8 MJ / kg.

[0009] In the second aspect of the present invention, a preparation method of the chain-substituted tricyclic fused cycloalkane compounds described in the above technical solution is provided. The method includes the following steps:

[0010] S1: In the presence of a catalyst, a carbon-carbon coupling cyclization reaction occurs between a substituted ketene itself or between a substituted ketene and another substituted ketene to obtain a compound parent molecule:

[0011]

[0012] S2: Hydrogenate and deoxygenate the compound parent molecule obtained in step S1 to obtain a tricyclic fused cycloalkane fuel molecule:

[0013]

[0014] Further, in step S1, the catalyst is one or more of KOH, NaOH, LiOH, Ca(OH)2, Mg(OH)2, Ba(OH)2, KF, NaF, LiF, CaF2, MgF2, BaF2, CsF2, BeF2, CaO, MgO, BaO, BeO.

[0015] Further, in step S1, the addition amount of the catalyst is 10 wt% - 20 wt% of the reactants; the reaction temperature is 60 °C - 120 °C, and the reaction time is 10 h - 24 h.

[0016] Further, in step S1, the substituted cycloalkenone is 2 - cyclopentenone, 3 - methyl - 2 - cyclopentenone, 4 - methyl - 2 - cyclopentenone, 5 - methyl - 2 - cyclopentenone, 4,4’ - dimethyl - 2 - cyclopentenone, 3,4 - dimethyl - 2 - cyclopentenone, 3,5 - dimethyl - 2 - cyclopentenone, 4,5 - dimethyl - 2 - cyclopentenone, 3,4,4’ - trimethyl - 2 - cyclopentenone, 3,4,5 - trimethyl - 2 - cyclopentenone, 3 - ethyl - 2 - cyclopentenone, 4 - ethyl - 2 - cyclopentenone, 5 - ethyl - 2 - cyclopentenone, 4,4’ - diethyl - 2 - cyclopentenone, 3,4 - diethyl - 2 - cyclopentenone, 3,5 - diethyl - 2 - cyclopentenone, 4,5 - diethyl - 2 - cyclopentenone, 3,4,4’ - triethyl - 2 - cyclopentenone, 3,4,5 - triethyl - 2 - cyclopentenone, 2 - cyclohexenone, 2 - methyl - 2 - cyclohexenone, 3 - methyl - 2 - cyclohexenone, 4 - methyl - 2 - cyclohexenone, 5 - methyl - 2 - cyclohexenone, 6 - methyl - 2 - cyclohexenone, 2,3 - dimethyl - 2 - cyclohexenone, 2,4 - dimethyl - 2 - cyclohexenone, 2,5 - dimethyl - 2 - cyclohexenone, 2,6 - dimethyl - 2 - cyclohexenone, 3,4 - dimethyl - 2 - cyclohexenone, 3,5 - dimethyl - 2 - cyclohexenone, 3,6 - dimethyl - 2 - cyclohexenone, 4,5 - dimethyl - 2 - cyclohexenone, 4,6 - dimethyl - 2 - cyclohexenone, 5,6 - dimethyl - 2 - cyclohexenone, 2 - ethyl - 2 - cyclohexenone, 3 - ethyl - 2 - cyclohexenone, 4 - ethyl - 2 - cyclohexenone, 5 - ethyl - 2 - cyclohexenone, 6 - ethyl - 2 - cyclohexenone, 2,3 - diethyl - 2 - cyclohexenone, 2,4 - diethyl - 2 - cyclohexenone, 2,5 - diethyl - 2 - cyclohexenone, 2,6 - diethyl - 2 - cyclohexenone, 3,4 - diethyl - 2 - cyclohexenone, 3,5 - diethyl - 2 - cyclohexenone, 3,6 - diethyl - 2 - cyclohexenone, 4,5 - diethyl - 2 - cyclohexenone, 4,6 - diethyl - 2 - cyclohexenone, 5,6 - diethyl - 2 - cyclohexenone, 2,3,4 - trimethyl - 2 - cyclohexenone, 2,3,5 - trimethyl - 2 - cyclohexenone, 2,3,6 - trimethyl - 2 - cyclohexenone, 3,4,5 - trimethyl - 2 - cyclohexenone, 3,4,6 - trimethyl - 2 - cyclohexenone, 4,5,6 - trimethyl - 2 - cyclohexenone, 3 - methyl - 2 - cycloheptenone, 4 - methyl - 2 - cycloheptenone, 5 - methyl - 2 - cycloheptenone, 4,4’ - dimethyl - 2 - cycloheptenone, 3,4 - dimethyl - 2 - cycloheptenone, 3,5 - dimethyl - 2 - cycloheptenone, 4,5 - dimethyl - 2 - cycloheptenone, 3,4,4’ - trimethyl - 2 - cycloheptenone, 3,4,5 - trimethyl - 2 - cycloheptenone, 3 - ethyl - 2 - cycloheptenone, 4 - ethyl - 2 - cycloheptenone, 5 - ethyl - 2 - cycloheptenone, 4,One or more of 4’-diethyl-2-cycloheptenone, 3,4-diethyl-2-cycloheptenone, 3,5-diethyl-2-cycloheptenone, 4,5-diethyl-2-cycloheptenone, 3,4,4’-triethyl-2-cycloheptenone, and 3,4,5-triethyl-2-cycloheptenone.,

[0017] Further, in step S2, the conditions for hydrodeoxygenation of the compound parent molecule are: in the presence of a catalyst, the reaction temperature is 150°C to 200°C, the hydrogen pressure is 4 to 8 MPa, and the reaction time is 24 h to 48 h;

[0018] Further, in step S2, the catalyst is a catalyst formed by loading a metal on a support; wherein, the metal is one or more of copper, nickel, platinum, gold, and palladium; the support is one or more of Al2O3, SiO2, HZSM-5, Al-MCM-41, Hβ, SBA-15, and HY.

[0019] Further, in step S2, the addition amount of the catalyst accounts for 5% to 20% of the mass of the compound parent molecule.

[0020] The third aspect of the present invention provides an application of the chain-substituted tricyclic fused cycloalkane compound described in the above technical solution in a liquid propellant for an aerospace vehicle.

[0021] Compared with the prior art, the present invention has the following beneficial technical effects:

[0022] (1) The chain-substituted tricyclic fused cycloalkane compound of the present invention has excellent properties such as high density, high calorific value, low freezing point, and high thermal stability. In particular, its density is increased by more than 17.5% compared with traditional RP-3 aviation kerosene (0.78 g / cm 3 ). For aerospace vehicles with limited fuel tank volume, it can effectively improve the fuel-carrying mass and meet the application requirements of long range, high speed, and large load.

[0023] (2) The preparation method of the chain-substituted tricyclic fused cycloalkane compound of the present invention can be prepared by heterogeneous catalytic reaction and hydrodeoxygenation reaction under relatively mild conditions, has strong substrate universality, high selectivity of the target product, and has high industrial application value. Specific embodiments:

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] Currently, the synthetic strategies for biomass fuels mainly involve hydroxyalkylation / alkylation reactions, aldol condensation reactions, olefin polymerization reactions, cyclohexanone coupling reactions, and Michael addition reactions, etc. These synthetic processes are all limited to carbon chain growth, only increasing the number of carbons in the molecular structure, but lacking the construction of new ring units. Therefore, their fuel density highly depends on the characteristics of the cyclic raw materials themselves and it is very difficult to significantly improve the fuel density.

[0026] Therefore, the key to synthesizing high-performance biomass hydrocarbon fuels is to develop new reactions to construct polycyclic structures in order to further increase the fuel density. Based on the above considerations, the present invention provides a chain-substituted tricyclic fused cycloalkane compound, and the compound has the following molecular structure:

[0027]

[0028] Wherein, n = 1, 2 or 3; R1, R2, R3, and R4 are each H or -CH3 or -CH2CH3. The density of the compound is greater than 0.910 g / cm 3 , the freezing point is not higher than -50 °C, and the net calorific value by mass is not lower than 42.8 MJ / kg.

[0029] The preparation method of the above-mentioned chain-substituted tricyclic fused cycloalkane compound comprises the following steps:

[0030] S1: In the presence of a catalyst, a carbon-carbon coupling cyclization reaction occurs between a substituted ketene itself or between a substituted ketene and another substituted ketene to obtain a compound parent molecule:

[0031]

[0032] S2: The compound parent molecule obtained in step S1 is subjected to hydrodeoxygenation to obtain a tricyclic fused cycloalkane fuel molecule:

[0033]

[0034] In some embodiments, in step S1, the catalyst is one or more of KOH, NaOH, LiOH, Ca(OH)2, Mg(OH)2, Ba(OH)2, KF, NaF, LiF, CaF2, MgF2, BaF2, CsF2, BeF2, CaO, MgO, BaO, BeO.

[0035] In some embodiments, the addition amount of the catalyst is 10 wt% to 20 wt% of the reactant, and can be, for example, 10 wt%, 12 wt%, 15 wt%, 18 wt%, 20 wt%, etc.; the reaction temperature is 60 °C to 120 °C, and can be, for example, 60 °C, 65 °C, 70 °C, 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, etc.; the reaction time is 10 h to 24 h, and can be, for example, 10 h, 12 h, 15 h, 18 h, 20 h, 24 h, etc.

[0036] In some embodiments, in step S1, the substituted cycloalkenone is 2-cyclopentenone, 3-methyl-2-cyclopentenone, 4-methyl-2-cyclopentenone, 5-methyl-2-cyclopentenone, 4,4'-dimethyl-2-cyclopentenone, 3,4-dimethyl-2-cyclopentenone, 3,5-dimethyl-2-cyclopentenone, 4,5-dimethyl-2-cyclopentenone, 3,4,4'-trimethyl-2-cyclopentenone, 3,4,5-trimethyl-2-cyclopentenone, 3-ethyl-2-cyclopentenone, 4-ethyl-2-cyclopentenone, 5-ethyl-2-cyclopentenone, 4,4'-diethyl-2-cyclopentenone, 3,4-diethyl-2-cyclopentenone, 3,5-diethyl-2-cyclopentenone, 4,5-diethyl-2-cyclopentenone, 3,4,4'-triethyl-2-cyclopentenone, 3,4,5-triethyl-2-cyclopentenone, 2-cyclohexenone, 2-methyl-2-cyclohexenone, 3-methyl-2-cyclohexenone, 4-methyl-2-cyclohexenone, 5-methyl-2-cyclohexenone, 6-methyl-2-cyclohexenone, 2,3-dimethyl-2-cyclohexenone, 2,4-dimethyl-2-cyclohexenone, 2,5-dimethyl-2-cyclohexenone, 2,6-dimethyl-2-cyclohexenone, 3,4-dimethyl-2-cyclohexenone, 3,5-dimethyl-2-cyclohexenone, 3,6-dimethyl-2-cyclohexenone, 4,5-dimethyl-2-cyclohexenone, 4,6-dimethyl-2-cyclohexenone, 5,6-dimethyl-2-cyclohexenone, 2-ethyl-2-cyclohexenone, 3-ethyl-2-cyclohexenone, 4-ethyl-2-cyclohexenone, 5-ethyl-2-cyclohexenone, 6-ethyl-2-cyclohexenone, 2,3-diethyl-2-cyclohexenone, 2,4-diethyl-2-cyclohexenone, 2,5-diethyl-2-cyclohexenone, 2,6-diethyl-2-cyclohexenone, 3,4-diethyl-2-cyclohexenone, 3,5-diethyl-2-cyclohexenone, 3,6-diethyl-2-cyclohexenone, 4,5-diethyl-2-cyclohexenone, 4,6-diethyl-2-cyclohexenone, 5,6-diethyl-2-cyclohexenone, 2,3,4-trimethyl-2-cyclohexenone, 2,3,5-trimethyl-2-cyclohexenone, 2,3,6-trimethyl-2-cyclohexenone, 3,4,5-trimethyl-2-cyclohexenone, 3,4,6-trimethyl-2-cyclohexenone, 4,5,6-trimethyl-2-cyclohexenone, 3-methyl-2-cycloheptenone, 4-methyl-2-cycloheptenone, 5-methyl-2-cycloheptenone, 4,4'-dimethyl-2-cycloheptenone, 3,4-dimethyl-2-cycloheptenone, 3,5-dimethyl-2-cycloheptenone, 4,5-dimethyl-2-cycloheptenone, 3,4,4'-trimethyl-2-cycloheptenone, 3,4,5-trimethyl-2-cycloheptenone, 3-ethyl-2-cycloheptenone, 4-ethyl-2-cycloheptenone, 5-ethyl-2-cycloheptenone, 4,One or more of 4’-diethyl-2-cycloheptenone, 3,4-diethyl-2-cycloheptenone, 3,5-diethyl-2-cycloheptenone, 4,5-diethyl-2-cycloheptenone, 3,4,4’-triethyl-2-cycloheptenone, 3,4,5-triethyl-2-cycloheptenone.,

[0037] In some embodiments, in step S2, the conditions for hydrodeoxygenation of the compound parent molecule are as follows: in the presence of a catalyst, the reaction temperature is 150 °C to 200 °C, for example, it can be 150 °C, 170 °C, 180 °C, 190 °C, 200 °C, etc.; the hydrogen pressure is 4 to 8 MPa, for example, it can be 4 MPa, 6 MPa, 8 MPa, etc.; the reaction time is 24 h to 48 h, for example, it can be 24 h, 30 h, 36 h, 42 h, 48 h, etc.

[0038] In some embodiments, in step S2, the catalyst is a catalyst formed by loading a metal on a support; wherein, the metal is one or more of copper, nickel, platinum, gold, and palladium; the support is one or more of Al2O3, SiO2, HZSM-5, Al-MCM-41, Hβ, SBA-15, and HY.

[0039] In some embodiments, in step S2, the addition amount of the catalyst accounts for 5% to 20% of the mass of the compound parent molecule, for example, it can be 5%, 10%, 16%, 20%, etc.

[0040] In the preparation process of the chain-substituted tricyclic fused cycloalkane high-density fuel molecules provided by the present invention, the process conditions are mild, the substrate universality is strong, and the selectivity of the target product is high. Moreover, the synthesized fuel molecules simultaneously have excellent properties of high density, high calorific value, and low freezing point.

[0041] The following is described in conjunction with specific examples:

[0042] Table 1 shows Examples 1-30 of the synthesis reaction of the chain-substituted fused cycloalkane compound parent molecule.

[0043] Table 1 Synthesis reaction of the chain-substituted fused cycloalkane compound parent molecule

[0044]

[0045]

[0046]

[0047] Taking Example 1 in Table 1 as an example for the specific reaction steps: Weigh an appropriate amount of base catalyst and 3,5,5’-trimethyl-2-cyclohexen-1-one and place them in a flask, and stir and react at 120 °C under argon protection for 10 h. After the reaction solution is cooled, the fuel precursor is obtained by centrifugation, and the yield is 85%.

[0048] The reaction conditions and yields of Examples 1 - 30 are shown in Table 1.

[0049] Table 2 shows Examples 31 - 60 of the hydrodeoxygenation reaction of the parent molecule of the compound.

[0050] Table 2 Hydrodeoxygenation reaction of the parent molecule of the compound

[0051]

[0052]

[0053] Taking Example 36 in Table 2 of the hydrodeoxygenation reaction of the parent molecule of the compound as an example, the specific steps are as follows: Add 30 g of the parent molecule of the compound obtained in Example 6 and 3 g of Pt / Hβ catalyst into a 100 mL autoclave, seal it, displace it with N2 three times, then fill it with H2 at 6 MPa, stir and heat up to 170 °C, and react for 48 h. Analyze the reaction solution by gas chromatography - mass spectrometry to qualitatively analyze the products and calculate the reaction yield. The fuel parent is completely converted, and the yield of the target product, the chain - substituted polycyclic naphthene - type fuel molecule, is 93%. The reaction conditions and yields of Examples 31 - 35 and 37 - 60 are shown in Table 2.

[0054] As can be seen from the above, the reactant containing the α,β - unsaturated aldehyde - ketone structure can obtain chain - substituted tricyclic polycyclic naphthene - type compounds in high yield through self - condensation reaction and hydrodeoxygenation reaction. After measurement, preferably, the density of the chain - substituted polycyclic naphthene - type fuel obtained in Example 31 is 0.918 g / cm 3 , the freezing point is - 55 °C, and the net calorific value by mass is 42.85 MJ / kg. Its density is 17.7% higher than that of traditional RP - 3 aviation kerosene (0.78 g / cm 3 ). Therefore, this route provides a new idea for the design and synthesis of high - energy - density fuel molecules in the future.

[0055] It should be noted that in this article, terms such as "including", "comprising" or any other variant thereof are intended to cover non - exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or elements inherent to such a process, method, article or device.

[0056] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation method of chain-substituted tricyclic fused cycloalkane compounds, characterized in that the compounds have the following molecular structure: ； wherein, n = 1, 2 or 3; R1, R2, R3, R4 are each H or -CH3 or -CH2CH3; the method comprises the following steps: S1: In the presence of a catalyst, carbon-carbon coupling cyclization reaction occurs between a substituted ketene itself or between a substituted ketene and another substituted ketene to obtain a compound parent molecule: ； S2: Hydrogenating and deoxygenating the compound parent molecule obtained in step S1 to obtain a tricyclic fused cycloalkane fuel molecule: 。 2. The method for preparing a chain-substituted tricyclic fused cycloalkane compound according to claim 1, characterized in that, The density of the compound is greater than 0.910 g / cm 3 , the freezing point is not higher than -50 °C, and the net calorific value by mass is not lower than 42.8 MJ / kg.

3. The preparation method of the chain-substituted tricyclic fused cycloalkane compounds according to claim 1, characterized in that, In step S1, the catalyst is one or more of KOH, NaOH, LiOH, Ca(OH)2, Mg(OH)2, Ba(OH)2, KF, NaF, LiF, CaF2, MgF2, BaF2, CsF2, BeF2, CaO, MgO, BaO, BeO.

4. The preparation method of the chain-substituted tricyclic fused cycloalkane compound according to claim 1, characterized in that, In step S1, the addition amount of the catalyst is 10wt% - 20wt% of the reactants; the reaction temperature is 60°C - 120°C, and the reaction time is 10h - 24h.

5. The method for preparing a chain-substituted tricyclic condensed cycloalkane compound according to claim 1, characterized in that, In step S1, the substituted cycloalkenone is 2-cyclopentenone, 3-methyl-2-cyclopentenone, 4-methyl-2-cyclopentenone, 5-methyl-2-cyclopentenone, 4,4'-dimethyl-2-cyclopentenone, 3,4-dimethyl-2-cyclopentenone, 3,5-dimethyl-2-cyclopentenone, 4,5-dimethyl-2-cyclopentenone, 3,4,4'-trimethyl-2-cyclopentenone, 3,4,5-trimethyl-2-cyclopentenone, 3-ethyl-2-cyclopentenone, 4-ethyl-2-cyclopentenone, 5-ethyl-2-cyclopentenone, 4,4'-diethyl-2-cyclopentenone, 3,4-diethyl-2-cyclopentenone, 3,5-diethyl-2-cyclopentenone, 4,5-diethyl-2-cyclopentenone, 3,4,4'-triethyl-2-cyclopentenone, 3,4,5-triethyl-2-cyclopentenone, 2-cyclohexenone, 2-methyl-2-cyclohexenone, 3-methyl-2-cyclohexenone, 4-methyl-2-cyclohexenone, 5-methyl-2-cyclohexenone, 6-methyl-2-cyclohexenone, 2,3-dimethyl-2-cyclohexenone, 2,4-dimethyl-2-cyclohexenone, 2,5-dimethyl-2-cyclohexenone, 2,6-dimethyl-2-cyclohexenone, 3,4-dimethyl-2-cyclohexenone, 3,5-dimethyl-2-cyclohexenone, 3,6-dimethyl-2-cyclohexenone, 4,5-dimethyl-2-cyclohexenone, 4,6-dimethyl-2-cyclohexenone, 5,6-dimethyl-2-cyclohexenone, 2-ethyl-2-cyclohexenone, 3-ethyl-2-cyclohexenone, 4-ethyl-2-cyclohexenone, 5-ethyl-2-cyclohexenone, 6-ethyl-2-cyclohexenone, 2,3-diethyl-2-cyclohexenone, 2,4-diethyl-2-cyclohexenone, 2,5-diethyl-2-cyclohexenone, 2,6-diethyl-2-cyclohexenone, 3,4-diethyl-2-cyclohexenone, 3,5-diethyl-2-cyclohexenone, 3,6-diethyl-2-cyclohexenone, 4,5-diethyl-2-cyclohexenone, 4,6-diethyl-2-cyclohexenone, 5,6-diethyl-2-cyclohexenone, 2,3,4-trimethyl-2-cyclohexenone, 2,3,5-trimethyl-2-cyclohexenone, 2,3,6-trimethyl-2-cyclohexenone, 3,4,5-trimethyl-2-cyclohexenone, 3,4,6-trimethyl-2-cyclohexenone, 4,5,6-trimethyl-2-cyclohexenone, 3-methyl-2-cycloheptenone, 4-methyl-2-cycloheptenone, 5-methyl-2-cycloheptenone, 4,4'-dimethyl-2-cycloheptenone, 3,4-dimethyl-2-cycloheptenone, 3,5-dimethyl-2-cycloheptenone, 4,5-dimethyl-2-cycloheptenone, 3,4,4'-trimethyl-2-cycloheptenone, 3,4,5-trimethyl-2-cycloheptenone, 3-ethyl-2-cycloheptenone, 4-ethyl-2-cycloheptenone, 5-ethyl-2-cycloheptenone, 4,4'-diethyl-2-cycloheptenone, 3,One or more of 4 - diethyl - 2 - cycloheptenone, 3,5 - diethyl - 2 - cycloheptenone, 4,5 - diethyl - 2 - cycloheptenone, 3,4,4’ - triethyl - 2 - cycloheptenone, 3,4,5 - triethyl - 2 - cycloheptenone., 6. The method for preparing a chain-substituted tricyclic fused cycloalkane compound according to claim 1, wherein In step S2, the conditions for hydrogenating and deoxygenating the compound parent molecule are: in the presence of a catalyst, the reaction temperature is 150°C - 200°C, the hydrogen pressure is 4 - 8MPa, and the reaction time is 24h - 48h.

7. The preparation method of the chain-substituted tricyclic fused cycloalkane compound according to claim 6, characterized in that, In step S2, the catalyst is a catalyst formed by loading a metal on a support; wherein, the metal is one or more of copper, nickel, platinum, gold and palladium; the support is one or more of Al2O3, SiO2, HZSM-5, Al-MCM-41, Hβ, SBA-15 and HY.

8. The preparation method of the chain-substituted tricyclic fused cycloalkane compound according to claim 6, characterized in that, In step S2, the addition amount of the catalyst accounts for 5% - 20% of the mass of the compound parent molecule.

9. Use of the chain-substituted tricyclic fused cycloalkane compounds obtained by the preparation method according to any one of claims 1 - 8 in liquid propellants for aerospace vehicles.

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