A method for producing a high energy density fuel

Abstract

The application discloses a preparation method of fuel, which comprises the following steps: (1) taking guaiacol derivative and / or eugenol derivative as single raw material, adding a catalyst with a core-shell structure, and reacting under certain conditions to obtain an oxygen-free fuel precursor; and (2) catalytically hydrogenating the oxygen-free fuel precursor obtained in the step (1) to obtain the fuel. The application further discloses the fuel obtained by the preparation method.

Description

Technical Field

[0001] This invention belongs to the field of fuel technology, specifically relating to a method for preparing high-energy-density fuels using guaiacol-based derivatives and / or eugenol-based derivatives as single raw materials. Background Technology

[0002] Fuel density and calorific value are key factors determining spacecraft flight performance. High-energy-density liquid fuels can be used in turbojet, ramjet, rocket, and combined-fuel engines. The development of the aerospace industry has placed higher demands on high-density fuels: on the one hand, they require fuels to provide more propulsive kinetic energy within a given fuel tank volume (i.e., higher density and higher volumetric calorific value, density > 0.85 g / mL); on the other hand, they require safe use in lower temperature environments, i.e., good low-temperature fluidity and good thermal stability. High-energy-density fuel is an abbreviation for high-density liquid hydrocarbon fuels. RJ-4 (bridged tetrahydromethyldicyclopentadiene dimer) and JP-10 (hanging tetrahydrodicyclopentadiene) are classic petroleum-based high-energy-density fuels, widely recognized for their excellent overall properties. They are typically synthesized from petroleum-based feedstocks such as cyclopentadiene or methylcyclopentadiene. However, feedstock sources are limited, and these fuels produce large amounts of CO2 during combustion. With increasing national concern for environmental and resource issues, exploring green high-energy-density fuel technologies is of great significance.

[0003] Lignin is one of the sources of pure natural aromatic compounds. It is a three-dimensional amorphous macromolecule composed of various cross-linked phenylpropane (C3-C6) units such as p-hydroxyphenyl, guaiacol, and eugenyl, linked by ether bonds (β-O-4, α-O-4, 4-O-5, etc.) and carbon-carbon bonds (β-5, 5-5, etc.). The annual industrial production of lignin can reach 50 million tons, and in recent years, reports on the synthesis of high-density fuels from lignin extracts have been increasing. The literature Journal of Energy Chemistry 77(2023)452–460 reports the use of lignin oil and externally added cyclopentanol for alkylation and hydrodeoxygenation to obtain high-energy-density fuels. Patent CN111218308 A discloses the preparation of 2,5-hexanedione from biomass raw materials, followed by the acquisition of oxygen-containing organic compounds from 2,5-hexanedione through aldol condensation and hydrogenation, and then hydrodeoxygenation to obtain high-density fuels. CN116676098A discloses a method for preparing high-energy-density fuels in a one-pot process using biomass phenols and added cyclic alcohols (cyclopentanol, cyclohexanol). Other documents such as Catalysis Today 365(2021)235–240; Chemical Engineering Science 207(2019)441–447; ACS Sustainable Chem.Eng.2021,9,7112-7119; Fuel 97(2012)560–568; EnergyFuels Chemical Engineering Science Methods for preparing high-energy-density fuels using lignin extracts as raw materials have also been reported in Angew. Chem. Int. Ed. 2019, 58, 12154 and Sustainable Energy Fuels, 2022, 6, 1616–1624.

[0004] However, these methods have the following problems: 1. Although the raw materials use one or more specific molecules of lignin extract, other components need to be added as raw materials to promote the reaction, increasing the complexity of the raw material source. 3. The high-density fuel precursor contains oxygen, and then harsh conditions of hydrodeoxygenation are required to obtain the high-density fuel. The steps are not only cumbersome but also reduce the product yield and place higher demands on the equipment. 4. The raw materials use one or more specific molecules of lignin extract, but the raw materials are singular. The components of the high-energy-density fuel product are mostly single or a mixture of two, resulting in the need to improve the overall performance of the product; currently, liquid fuels with a density exceeding 1.0 g / mL are rare. 5. The use of acidic catalysts such as concentrated sulfuric acid results in heavy pollution.

[0005] The present invention is proposed to solve the above problems. Summary of the Invention

[0006] This invention utilizes guaiacol-based and eugenol-based derivatives as single raw materials, employing a newly synthesized core-shell catalyst in a one-pot series process to prepare high-energy, high-density fuel precursors. The resulting fuel precursors are oxygen-free, similar to classic petroleum-based high-density fuel precursors. Simple and mild hydrogenation then yields saturated alkane-based classic petroleum-based high-density fuels. The method of this invention features a simple synthesis process, oxygen-free fuel precursors, mild hydrogenation conditions, a three-dimensional fuel structure, and complementary components; the resulting fuel has a density greater than 0.96 g / mL. -1 .

[0007] The technical solution of the present invention is as follows:

[0008] The first aspect of the present invention discloses a method for preparing a fuel, comprising the following steps: (1) using guaiacol derivatives and / or eugenol derivatives as single raw materials, adding a catalyst with a core-shell structure, and reacting under certain conditions to obtain an oxygen-free fuel precursor; (2) catalytically hydrogenating the oxygen-free fuel precursor obtained in step (1) to obtain the fuel.

[0009] Preferably, the guaiacol-based derivative and / or eugenol-based derivative in step (1) are obtained by separating lignin, wherein the lignin is one or more of lignin sulfonate, beech, poplar, birch, or corn stalk. Of course, the guaiacol-based derivative and / or eugenol-based derivative can also be obtained from other sources such as petrochemical-based materials.

[0010] Preferably, the guaiacol-based derivative and / or eugenol-based derivative are: One or more of them.

[0011] Preferably, the catalyst with a core-shell structure comprises: metal nanoparticles, a non-acidic spherical core, and an acidic spherical outer shell, wherein the metal nanoparticles are loaded on the spherical core. The core and shell walls have hollow cavities. The core and shell can be regular spherical shells or irregular spherical shells, such as ellipsoidal shells, flattened spherical shells, or other irregular spherical shells.

[0012] Preferably, the core shell wall has pores with a diameter of 0.5nm-30nm, the average diameter of the hollow cavity inside the core shell wall is 5-200nm, and the thickness of the core shell wall is 5-100nm; the outer shell wall also has pores with a diameter that gradually decreases from the outside to the inside, from 5nm-100nm to 0.5nm-30nm, and the thickness of the outer shell wall is 5-500nm.

[0013] Preferably, the core is one or more of silicon dioxide, titanium dioxide, zirconium dioxide, cerium dioxide, magnesium oxide, calcium oxide, zinc oxide, or pure silicon molecular sieve, and the metal nanoparticles are one or more of the same, with the metal nanoparticles accounting for 5wt% to 50wt% of the core; the outer shell is one or more molecular sieves, one or more metal oxides, or a composite of one or more metal oxides and silicon dioxide, or a composite of one or more molecular sieves and silicon dioxide.

[0014] Preferably, the core-shell structured catalyst comprises: Ni / SiO2@NbWOx, Ni / SiO2@Al-MCM-41, Au / Silicalite-1@WO3, Ni / TiO2@Al-SBA-15, RuNiCu / ZrO2@Al-SBA-16, NiFe / MgO@Ti-MCM-41, Ni / SBA-15@HY, Ni / SiO2@Hβ, Ir / SBA-16@HZSM-5, NiCo / SiO2@Al2O3, Pt / M CM-48@Nb2O5, RuNiCu / ZrO2@SiO2-Al2O3, NiFe / MgO@CsTPA, Pt / ZnO@HfTPA / MCM-41, RuNi / CeO2@SiO2-Nb2O5, RhF e / MCM-41@MOF-808-2.5SO4, PtCu / MCM-22@HfTPA, RuMo / SiO2@SnTPA, RuNiCu / SiO2@ZrTPA, NiCoMo / Si-CeOx@SO4 2- / ZrO2、NiZn / Ce-MgO x @ITQ、NiIr / Ce-MgO x@KIT-6, Au / Silicalite-1@Mordenite, Ni / SiO2@MMT-K10, Ni / TiO2@HPW / MCM-41. The above expressions a / b@c, where a / b before @ indicates that metal nanoparticle a is loaded on the core b; after @ indicates the outer shell, and c indicates the outer shell composition; the above expressions a / b@c / d, where a / b before @ indicates that metal nanoparticle a is loaded on the core b; after @ indicates the outer shell, and c / d indicates a composite of outer shell components c and d.

[0015] Preferably, the reaction temperature in step (1) is 150℃~350℃, the hydrogen pressure is 2~6MPa, and the reaction time is 5~30h; the catalyst accounts for 5wt%~20wt% of the mass of the reactants.

[0016] Preferably, the conditions for the catalytic hydrogenation reaction of the oxygen-free fuel precursor in step (2) are: temperature of 60℃~180℃, hydrogen pressure of 2~6MPa, and reaction time of 2~10h; the catalyst for catalytic hydrogenation is one or more of Pd / C, Ni / SiO2, NiCo / MCM-41, PtO, RuNiCu / SBA-15, NiFe / SBA-16, Pt / C, RuNi / SiO2, RhFe / MCM-41, PtCu / HZSM-5, RuMo / Hβ, Pd / SAPO-11, Ni / HY, Ru / Al2O3, Rh / Al2O3-SiO2, Ni / Nb2O5, and Ni / Al-MCM-41; the catalyst accounts for 5wt%~20wt% of the mass of the oxygen-free fuel precursor.

[0017] The second aspect of this invention discloses that the fuel obtained by the preparation method described above is a high-energy-density fuel, with a density greater than 0.96 g·mL. -1 Freezing point below -50℃, kinetic viscosity less than 10.90 mm. 2 The fuel has a heat value of 39.0 MJ / kg and a calorific value of 20°C / s (at 20°C). The resulting fuel can be used for jet fuel production or for the preparation of jet fuel.

[0018] The beneficial effects of this invention are:

[0019] 1. The preparation method of this invention directly uses guaiacol-based derivatives and / or eugenol-based derivatives as single raw materials. The guaiacol-based and eugenol-based derivatives used are isolated from one or more of lignin sulfonates, beech, poplar, birch, or corn stalks; these raw materials can be mixed in any proportion and used simultaneously to react with each other to prepare high-density fuel precursors. The synthesized fuel is a mixture containing multiple components, allowing for complementary advantages between the components. These guaiacol-based and eugenol-based derivatives can also be obtained from other sources such as petrochemical-based materials; therefore, the raw material sources are wide-ranging. Furthermore, this invention uses these raw materials as single raw materials, eliminating the need for additional raw materials to participate in the reaction process.

[0020] 2. The preparation method of this invention uses a newly developed catalyst with a core-shell structure to achieve direct, multi-step, tandem preparation of fuel precursors under single-pot conditions, avoiding multiple intermediate product separation and transfer processes and simplifying the preparation process. The feed conversion rate is 100%, and the yield of high-density fuel precursors can reach over 70%, with a maximum of 98%. The obtained fuel precursors are oxygen-free, containing only C=C single bonds and unsaturated C=C double bonds, and further hydrogenation is easily achieved under mild conditions. The final fuel molecule is a mixture of classic petroleum-based JP-10 and RJ-4 structures, with complementary components; the density is greater than 0.96 g / mL. -1 Freezing point below -50℃, kinetic viscosity less than 10.90 mm. 2 / s (20℃), calorific value greater than 39.0MJ / Kg.

[0021] 3. The newly developed core-shell structured catalysts of this invention include: Ni / SiO2@NbWOx, Ni / SiO2@Al-MCM-41, Au / Silicalite-1@WO3, Ni / TiO2@Al-SBA-15, RuNiCu / ZrO2@Al-SBA-16, NiFe / MgO@Ti-MCM-41, Ni / SBA-15@HY, Ni / SiO2@Hβ, Ir / SBA-16@HZSM-5, NiCo / SiO2@Al2O3, Pt / MCM-48@Nb2O5, RuNiCu / ZrO2@SiO2-Al2O3, NiFe / MgO@CsTPA, Pt / ZnO@HfTPA / MCM-41, RuNi / CeO2@SiO2-Nb2O5, R hFe / MCM-41@MOF-808-2.5SO4, PtCu / MCM-22@HfTPA, RuMo / SiO2@SnTPA, RuNiCu / SiO2@ZrTPA, NiCoMo / Si-CeOx@SO4 2- / ZrO2、NiZn / Ce-MgO x@ITQ、NiIr / Ce-MgO x @KIT-6, Au / Silicalite-1@Mordenite, Ni / SiO2@MMT-K10, Ni / TiO2@HPW / MCM-41. The newly developed core-shell structured catalyst and its preparation method are described in patent CN2024110013158.

[0022] 4. The preparation method of this invention can obtain high-density fuel using a one-pot series process. However, the newly developed core-shell structured catalyst does not exhibit the same catalytic hydrogenation effect as traditional hydrogenation catalysts, resulting in a lower yield. Existing catalytic hydrogenation methods can achieve higher yields in converting fuel precursors into high-energy, high-density fuels. Attached Figure Description

[0023] Figure 1 The GC-MS diagram of the fuel precursor obtained in Example 1 is shown (R1, R2, R3 represent hydrogen, methyl, ethyl, and propyl).

[0024] Figure 2 The image shows the GC-MS plot of the fuel obtained in Example 26 (R1, R2, R3 represent hydrogen, methyl, ethyl, and propyl). Detailed Implementation

[0025] The technical solution of the present invention will be described in detail below with reference to specific embodiments. Unless otherwise specified, the raw materials used in the embodiments are all commercially available products; unless otherwise specified, the processes used are all conventional processes in the art.

[0026] Example 1: Preparation of fuel precursors.

[0027] 25 g of propylguaiacol and 2.00 g of a core-shell catalyst were added to a high-pressure reactor, and the air was purged three times with nitrogen. Hydrogen gas was then introduced at 4 MPa, and the mixture was mechanically stirred at 600 rpm / min and reacted at 200 °C for 10 h. After the reaction was completed and the temperature dropped to room temperature, the catalyst was separated and analyzed. The results showed that the feed conversion rate was 100% and the yield of the fuel precursor was 90%. After dehydration, the resulting liquid was analyzed by gas chromatography. The GC-MS chromatogram of the product is shown below. Figure 1 As shown, dimers account for 85% of the fuel precursor, while trimers account for 15%.

[0028] The catalyst used is a core-shell structured Ni / SiO2@NbWOx catalyst; the core is metallic Ni supported on SiO2, with the loading of metallic Ni being 10 wt% of the total core; the shell is NbWOx. The applicant filed a separate patent application on the same day for the catalyst preparation method.

[0029] Examples 2-25: Preparation of fuel precursors.

[0030] Similar to Example 1, catalysts with core-shell structures, such as Ni / SiO2@NbWOx, Ni / SiO2@Al-MCM-41, Au / Silicalite-1@WO3, Ni / TiO2@Al-SBA-15, RuNiCu / ZrO2@Al-SBA-16, NiFe / MgO@Ti-MCM-41, Ni / SBA-15@HY, Ni / SiO2@Hβ, Ir / SBA-16@HZSM-5, NiCo / SiO2@Al2O3, and Pt / MCM-48@Nb2O5, RuNiCu / ZrO2@SiO2-Al2O3, NiFe / MgO@CsTPA, Pt / ZnO@HfTPA / MCM-41, RuNi / CeO2@SiO2-Nb2O5, Rh Fe / MCM-41@MOF-808-2.5SO4, PtCu / MCM-22@HfTPA, RuMo / SiO2@SnTPA, RuNiCu / SiO2@ZrTPA, NiCoMo / Si-CeOx@SO4 2- / ZrO2、NiZn / Ce-MgO x @ITQ、NiIr / Ce-MgO x @KIT-6, Au / Silicalite-1@Mordenite, Ni / SiO2@MMT-K10, Ni / TiO2@HPW / MCM-41, etc., were used as catalysts (the molar ratio of bimetallic compounds in the core was 1:20 to 20:1, and the molar ratio of trimetallic compounds was 1:20:1 to 20:1:20; other parameters were the same as in Example 1). The results of reactants and their amounts, catalysts and their amounts, reactant conversion rates, reaction temperatures, reaction times, and fuel precursor yields are listed in Table 1.

[0031] Table 1. Synthetic fuel precursors from guaiacol-based and / or eugenol-based derivatives.

[0032]

[0033]

[0034] As shown in Table 1, the conversion rate of the raw materials was 100%, and the yield of the fuel precursor was 75-98%.

[0035] Examples 26-50: Preparation of high-energy, high-density fuels. Using the fuel precursors obtained in Examples 1-25 as raw materials, Pd / C, Ni / SiO2, NiCo / MCM-41, PtO, RuNiCu / SBA-15, NiFe / SBA-16, Pt / C, RuNi / SiO2, RhFe / MCM-41, PtCu / HZSM-5, RuMo / Hβ, Pd / SAPO-11, Ni / HY, Ru / Al2O3, and Rh / Al2O3-S were prepared. One or more of iO2, Ni / Nb2O5, and Ni / Al-MCM-41 are used as catalysts, accounting for 5wt% to 20wt% of the mass of the oxygen-free fuel precursor (if the catalyst is a bimetallic molar ratio of 1:10 to 10:1, or a trimetallic molar ratio of 1:20:1 to 20:1:20, the SiO2 / Al2O3 ratio of the molecular sieve used is in the range of 10 to 200), and the fuel precursor is mildly hydrogenated to produce high-energy, high-density fuel.

[0036] High-energy, high-density fuels were prepared by mild hydrogenation using the fuel precursors obtained in Examples 1-25, respectively. The fuel precursors and catalysts obtained in Examples 1-25 were added together to an autoclave (corresponding to Examples 26-50, respectively). Air was purged three times with nitrogen, followed by hydrogen injection. The mixture was mechanically stirred and reacted at a certain temperature for a period. After the reaction was complete and the temperature dropped to room temperature, the catalyst was separated. The analysis results showed that the fuel precursor conversion rate was 100%. The reactants and their amounts, catalyst and its amount, reactant conversion rate, reaction temperature, and reaction time are shown in Table 2. The fuel yield, and the mass percentages of dimers and trimers are also shown in Table 2. Analysis of the product obtained in Example 26 showed that the fuel precursor conversion rate was 100%, and the fuel yield was 94%. Gas chromatography analysis was performed, and the GC-MS chromatogram of the product is shown below. Figure 2 As shown, the results indicate that dimers account for 85% of the fuel, while trimers account for 15%.

[0037] Table 2. Preparation of High-Energy, High-Density Fuels via Hydrogenation of Fuel Precursors

[0038]

[0039]

[0040] As shown in Table 2, the conversion rate of fuel precursors is 100%, and the yield of high-energy, high-density fuel is not less than 91%.

[0041] The fuel obtained in Example 26 was subjected to density determination according to the national standard GB2540-81 "Determination of Density of Petroleum Products", and the result was 1.12 g·mL⁻¹. -1The freezing point was determined according to the national standard GB2430-81 "Determination of Freezing Point of Jet Fuel", and was below -70℃; the kinetic viscosity was determined according to the national standard GB265-88 "Determination of Kinematic Viscosity and Calculation of Dynamic Viscosity of Petroleum Products", and was 1.85 mm. 2 / s (20℃); its calorific value was determined according to the national standard GB / T 384-81 "Determination of Calorific Value of Petroleum Products", and was 41.1 MJ / Kg.

[0042] The fuel measured in Example 33 had a density of 1.31 g / mL. -1 Freezing point is below -50℃; kinetic viscosity is 1.65 mm. 2 / s (20℃); its calorific value was determined to be 41.5 MJ / Kg according to the national standard GB / T 384-81 "Determination of Calorific Value of Petroleum Products".

[0043] The fuel densities obtained in other embodiments were all greater than 0.96 g·mL⁻¹. -1 The highest value was 1.30 g / mL. -1 The freezing point is below -50℃, with a minimum of -110℃; its kinetic viscosity is less than 10.90 mm. 2 / s (20℃), minimum is 1.95mm 2 / s (20℃); its calorific value is greater than 39.0MJ / Kg, with a maximum of 43.2MJ / Kg.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a fuel, characterized in that, The steps include: (1) using guaiacol derivatives and / or eugenol derivatives as single raw materials, adding a catalyst with a core-shell structure, and reacting under certain conditions to obtain an oxygen-free fuel precursor; (2) Catalytically hydrogenate the oxygen-free fuel precursor obtained in step (1) to obtain the fuel; The catalyst with a core-shell structure comprises: metal nanoparticles, a non-acidic spherical core, and an acidic spherical shell, wherein the metal nanoparticles are loaded on the spherical core; The core shell has pores with a diameter of 0.5 nm-30 nm, the average diameter of the hollow cavity inside the core shell is 5-200 nm, and the thickness of the core shell is 5-100 nm; the outer shell also has pores with a diameter that gradually decreases from the outside to the inside, from 5 nm-100 nm to 0.5 nm-30 nm, and the thickness of the outer shell is 5-500 nm. The core is made of silicon dioxide, and metal nanoparticles account for 5 wt% to 50 wt% of the core. The core-shell structured catalyst is one or more of Ni / SiO2@NbWOx, Ni / SiO2@Al-MCM-41, Ni / SiO2@Hβ, NiCo / SiO2@Al2O3, and Ni / SiO2@MMT-K10.

2. The preparation method according to claim 1, characterized in that, The guaiacol-based derivative and / or eugenol-based derivative in step (1) are obtained by separating lignin from lignin, wherein the lignin is one or more of lignin sulfonate, beech, poplar, birch or corn stalk.

3. The preparation method according to claim 1 or 2, characterized in that, The guaiacol-based derivative and / or eugenol-based derivative are: ， One or more of them.

4. The preparation method according to claim 1, characterized in that, Step (1) The reaction temperature is 150℃ ~ 350℃, the hydrogen pressure is 2 ~ 6 MPa, and the reaction time is 5 ~ 30h; the catalyst accounts for 5wt% ~ 20wt% of the mass of the reactants.

5. The preparation method according to claim 1, characterized in that, The conditions for the catalytic hydrogenation reaction of the oxygen-free fuel precursor in step (2) are as follows: temperature 60℃ ~ 180℃, hydrogen pressure 2 ~ 6 MPa, reaction time 2 ~ 10 h; the catalyst for catalytic hydrogenation is one or more of Pd / C, Ni / SiO2, NiCo / MCM-41, PtO, RuNiCu / SBA-15, NiFe / SBA-16, Pt / C, RuNi / SiO2, RhFe / MCM-41, PtCu / HZSM-5, RuMo / Hβ, Pd / SAPO-11, Ni / HY, Ru / Al2O3, Rh / Al2O3-SiO2, Ni / Nb2O5, Ni / Al-MCM-41; the catalyst accounts for 5wt% ~ 20wt% of the mass of the oxygen-free fuel precursor.

6. The fuel obtained by the preparation method according to any one of claims 1-5, characterized in that, The density of the fuel was measured to be greater than 0.96 g / mL. -1 Freezing point below -50 o C, kinetic viscosity less than 10.90 mm 2 / s, calorific value greater than 39.0 MJ / Kg.

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