Method for preparing high-density aviation fuel by catalyzing turpentine with Bronsted acid

Abstract

The invention discloses a method for preparing high-density aviation fuel by catalyzing turpentine with Bronsted acid. The method comprises the following specific steps: step 1, regulating the strength of Bronsted acid to catalyze the isomerization reaction of terpenoids in turpentine, firstly generating cyclohexene and cyclohexadiene intermediates, and then performing Diels-Alder dimerization addition reaction on the intermediates generated by isomerization under the catalysis of the acid to generate a polycyclic high-density fuel precursor with the carbon number of 20; and 2, carrying out hydrogenation on C = C double bonds in the double-ring structure of the high-density aviation fuel precursor with the carbon number of 20 under the catalysis of a hydrogenation catalyst so as to generate the high-density aviation fuel. The invention provides a novel method for preparing high-density aviation fuel from biomass platform compound turpentine, and the whole preparation process is simple and convenient to operate.

Description

Technical Field

[0001] The invention relates to the technical field of compound organic synthesis, and in particular to a method for preparing high-density aviation fuel using turpentine oil catalyzed by Bronsted acid. Background Art

[0002] High-density hydrocarbon fuels usually refer to artificially synthesized fuels with a density greater than 0.80 g / cm 3 Alkane fuels provide important power guarantees for various aerospace vehicles such as missiles, rockets and fighters, and are the research focus in the field of propellants. With the development of modern advanced technology, it is very necessary to improve the flight performance of aircraft (including high speed, long range, large load and high flexibility, etc.), which also puts forward higher requirements for the power propulsion capability of aircraft. Among them, improving the density and volume calorific value of fuel is an important way to enhance the propulsion performance of aircraft at low cost. The greater the calorific value of the fuel, the greater the energy released by its unit volume combustion, and the smaller the required fuel tank volume, which is more beneficial to improving the performance of the aircraft. For an aircraft with a certain fuel tank volume, the higher the density of the fuel, the greater the fuel mass it can carry, and the longer the range of the aircraft; under the condition of a certain total thrust of the aircraft, the higher the density of the fuel it carries, the smaller the required fuel tank volume, which is conducive to the miniaturization of the aircraft and improving its penetration capability and flexibility.

[0003] Turpentine is mainly derived from plant metabolites, with an annual production of 330,000 tons. α-pinene and β-pinene are two important terpene compounds and are also the main components of turpentine. Pinene isomerization can produce many chemicals. For example, α-pinene can be used to prepare a mixture of camphene and limonene. The dimerization of α-pinene and β-pinene catalyzed by liquid or solid acids has also been widely studied (Tribology Transactions, 2006, 49(3): 454-472). In particular, mixing high-density fuels, including these hydrogenated dimers and other distillate fuels, is very meaningful for increasing the range of spacecraft (Energy & Fuels, 2013, 27(2): 883-888). Summary of the invention

[0004] The invention aims to provide a method for preparing high-density aviation fuel by using Bronsted acid-catalyzed turpentine oil, which has simple steps and high yield and can prepare aviation fuel with high density and high calorific value.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows: a method for preparing high-density aviation fuel by using Bronsted acid-catalyzed turpentine oil, comprising the following steps:

[0006] In the first step, the main terpene compounds 1 (such as α-pinene, β-pinene, limonene, etc.) in turpentine oil undergo an isomerization reaction under acid catalysis to generate intermediates with cyclohexene and cyclohexadiene structures, and the intermediates with cyclohexene and cyclohexadiene structures undergo Diels-Alde dimerization addition reaction with themselves or alternately under acid catalysis to generate a high-density fuel precursor 2 with a carbon number of 20 (C20); the acid is selected from one or more of the following catalysts: H2SO4, p-toluenesulfonic acid, trifluoroacetic acid, acetic acid, Nafion, T-62MP, Amberlyst15, Al-MCM-41 (silicon-aluminum ratios are 60, 40, 20, respectively), HPW / SiO2, HPW / MCM-41, MCM-41, D600, CD750, CD250; wherein the ratio of the mass of the acid to the mass of the reaction substrate is between 0.01 and 0.5;

[0007]

[0008] The second step is to generate a C20 high-density fuel precursor 2, and then perform a hydrogenation reaction under the catalysis of a hydrogenation catalyst to generate a high-density aviation fuel 3;

[0009]

[0010] Preferably, in the first step, the solvent used is selected from one or more of propylene carbonate, acetonitrile, toluene, cyclohexane, tetrahydrofuran, dichloromethane, ethyl acetate, N,N-dimethylformamide, dichloroethane, methanol, and isopropanol, and the substrate concentration range is 0.01-1 mol / L; the reaction temperature is between 120-140° C., and the reaction time is between 3-6 h.

[0011] Preferably, in the second step, the hydrogenation catalyst is selected from one of Raney Ni, Raney Co, Pt / C, Pd / C, Ru / C, Ir / C, Rh / C, Co / C, Ni / C, and Fe / C; wherein the ratio of the amount of the catalyst to the mass of the fuel precursor 2 is between 0.01 and 0.3.

[0012] Preferably, in the second step, the solvent used is selected from one or more of cyclohexane, acetonitrile, propylene carbonate, methanol, propanol, isopropanol, tridecane, toluene, tetrahydrofuran, N,N-dimethylformamide, n-hexane, and ethyl acetate, and the substrate concentration range is 0.01-1 mol / L.

[0013] Preferably, in the second step, the hydrogenation reaction temperature is between 100-200° C., the reaction time is between 5-10 h, and the hydrogen pressure is between 3-5 MPa.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. The present invention can completely realize the preparation of high-density C20 aviation fuel with high yield from biomass platform compounds such as α-pinene, β-pinene, limonene and other terpenoid compounds through a two-step method. The density of the high-density C20 aviation fuel is greater than 0.90 g / mL, and the high-performance aviation kerosene alkane compound is obtained.

[0016] 2. The entire route uses biomass as raw material. It is a new green route that does not produce harmful substances. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Example 7: MS spectra of isomerization and DA cycloaddition products using Masson pine turpentine as raw material;

[0018] Figure 2 Example 8 GC spectra of isomerization and DA cycloaddition dimerization products using Masson pine turpentine as raw material;

[0019] Figure 3 Example 9: GC spectra of isomerization and DA cycloaddition dimerization products using Masson pine turpentine as raw material;

[0020] Figure 4 Example 11 Using Masson pine turpentine as raw material, GC spectra of isomerization and DA cycloaddition products

[0021] Figure 5 Example 21 Using α-pinene as raw material, MS spectra of isomerization and DA cycloaddition products;

[0022] Figure 6 Example 22 Using α-pinene as raw material, MS spectrum of isomerization and DA cycloaddition dimerization products;

[0023] Figure 7 Example 36 GC spectrum of isomerization and DA cycloaddition trimerization products using α-pinene as raw material;

[0024] Figure 8 Example 55 Using α-pinene as raw material, MS spectrum of isomerization and DA cycloaddition dimerization products;

[0025] Fig. 9 Example 67 MS spectrum of hydrogenation of aviation fuel precursor 2;

[0026] Fig.10 .GC spectrum of Example 67 aviation fuel precursor 2 hydrogenation. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] Example 1-63

[0029] Natural terpenoids (α-pinene, β-pinene and limonene) in turpentine undergo isomerization / Diels-Alder dimerization under acidic conditions to generate precursor 2 with a bicyclic structure (effects of catalyst, temperature, solvent and time)

[0030] Add turpentine (7 mmol, 0.952 g) into a 35 mL reaction tube, add 0.7 mmol of acid catalyst, and react at 120-140°C for 3-6 hours.

[0031]

[0032] Table 1. Effects of catalyst, temperature and solvent on isomerization / Diels-Alder dimerization reaction

[0033]

[0034]

[0035]

[0036] From the results in Table 1, it can be seen that the heterogeneous catalysts Amberlyst15, Al-MCM-41 (silicon-aluminum ratio of 20), T-62MP and Nafion and the homogeneous catalyst H2SO4 showed good catalytic performance in catalyzing the isomerization / Diels-Alder dimerization addition reaction of terpenoids, and achieved medium to high yields. Among them, T-62MP had the best catalytic performance, and the yield of dimerization products reached 86% at 120°C for 3h. At low temperature of 80°C, the catalytic effect of T-62MP was poor, and the yield of dimerization products was 65%. When the temperature was higher than 120°C, the catalyst activity decreased, resulting in a product yield lower than 86%. By screening different solvents, it was found that toluene, dimethyl carbonate and propylene carbonate had relatively good effects on the reaction, but toluene was selected as the solvent from the perspective of environmental greenness. By screening different reaction times, it was found that extending the time did not increase the product yield. The yield of dimerization products was 83% after 12h reaction, which was not much different from the result of 3h reaction.

[0037] Since the service life of the catalyst needs to be examined in practical applications, the recycling of T-62MP and HPW / SiO2 was studied using toluene as solvent and reacted at 120°C for 3 hours. After the first reaction, the product and catalyst will automatically separate into layers, with the upper layer being the product and the lower layer being the catalyst. The product is separated and turpentine is continued for the next cycle. From the results in Tables 2 and 3, it can be seen that the yield of DA product 3 does not change significantly when T-62MP is recycled four times and HPW / SiO2 is recycled three times, which shows that the reaction system can be reused.

[0038] Table 2. T-62MP cycle test

[0039]

[0040] Table 3. HPW / SiO2 cycle experiment

[0041]

[0042] The MS spectrum of the DA product obtained in Example 7 is as follows: Figure 1 As shown in the figure, it can be seen that the maximum mass-to-charge ratio of the molecular ion peak of the substance is m / z=272, while the molecular weight of pinene is 136 and the theoretical molecular weight of the dimerization product is 272, so the product is the target C20 precursor.

[0043] The GC spectrum of the DA product obtained in Example 8 is as follows: Figure 2 As shown. The gas chromatograph set the injection port temperature to 280℃, the initial column box temperature to 60℃, the heating rate to 15℃ / min, and the temperature was raised to 310℃ and maintained for 5min. The substance with a peak at 5.2min in the GC graph is the isomer camphene of α-pinene and β-pinene in turpentine oil, the substance with a peak at 5.9min is the isomeric aromatization intermediate p-methyl isopropylbenzene, the substance with a peak at 8min is the internal standard tridecane, and the substance appearing within 12-15min is the C20 high-density fuel precursor produced by the dimerization of pinene itself.

[0044] The GC spectrum of the DA product obtained in Example 9 is as follows: Figure 3 As shown. The gas chromatograph set the injection port temperature to 280°C, the initial column box temperature to 60°C, the heating rate to 15°C / min, and the temperature was raised to 310°C and maintained for 5 minutes. It can be seen from the GC graph that under the catalysis of Amberlyst-15 catalyst, the isomers produced by the isomerization of the main terpenoid compounds in turpentine oil and the substances produced by molecular sieve catalysis have the same peak time. The substance that peaks at 5.2min is camphene, and the substance that peaks at 5.9min is the isomeric aromatization intermediate p-methyl isopropylbenzene. The peak shapes of the dimerization products are different within 12 to 15 minutes, so the properties of the final hydrogenation products will be different.

[0045] The GC spectrum of the DA product obtained in Example 11 is as follows: Figure 4As shown. The gas chromatograph set the injection port temperature to 280°C, the initial column box temperature to 60°C, the heating rate to 15°C / min, and the temperature was raised to 310°C and maintained for 5 minutes. The gas phase diagram shows the isomerization / Diels-Alder reaction of turpentine oil catalyzed by T-62MP. The substance with a peak at 5.2min is camphene, the substance with a peak at 5.9min is p-methylisopropylbenzene, the substance with a peak at 6.6min is terpinolene, the substance with a peak at 8min is the internal standard tridecane, and the substance that appears within 12-15min is the C20 high-density fuel precursor produced by the dimerization of pinene itself.

[0046] The MS spectrum of the DA product obtained in Example 21 is as follows: Figure 5 As shown in the figure, it can be seen that the maximum mass-to-charge ratio of the molecular ion peak of the substance is m / z=272, while the molecular weight of pinene is 136, and the theoretical molecular weight of the dimerization product is 272, so the product is the target C20 precursor.

[0047] The MS spectrum of the DA product obtained in Example 22 is as follows: Figure 6 As shown in the figure, it can be seen that the maximum mass-to-charge ratio of the molecular ion peak of the substance is m / z=272, while the molecular weight of pinene is 136 and the theoretical molecular weight of the dimerization product is 272, so the product is the target C20 precursor.

[0048] The GC spectrum of the DA product obtained in Example 36 is as follows: Figure 7 As shown. The gas chromatograph set the injection port temperature to 280°C, the initial column box temperature to 60°C, the heating rate to 15°C / min, and the temperature was raised to 310°C and maintained for 5 minutes. The gas phase diagram shows the isomerization / Diels-Alder reaction of turpentine oil under HPW / SiO2 catalysis. The substance with a peak at 5.2min is camphene, the substance with a peak at 5.9min is p-methylisopropylbenzene, the substance with a peak at 8min is the internal standard tridecane, and the substance that appears within 12-15min is the C20 high-density fuel precursor produced by the dimerization of pinene itself.

[0049] The MS spectrum of the DA product obtained in Example 55 is as follows: Figure 8 As shown in the figure, it can be seen that the maximum mass-to-charge ratio of the molecular ion peak of the substance is m / z=272, while the molecular weight of pinene is 136 and the theoretical molecular weight of the dimerization product is 272, so the product is the target C20 precursor.

[0050] Examples 64-83

[0051] C20 high-density fuel precursor 2 is hydrogenated under the catalysis of Metal / C, Raney Ni, and Raney Co to produce high-density aviation fuel 3; (Influence of catalyst, temperature, and solvent)

[0052] In a 100mL reactor, C20 high-density fuel precursor 2 (14.96g, 55mmol) and 10mL solvent were added, and then 150mg catalyst (active metal loading 5wt%) was added. The reaction was carried out at a certain temperature and 3.5MPa hydrogen pressure for 10h to obtain high-density aviation fuel 3.

[0053]

[0054] Table 4. Effects of catalyst, temperature and solvent on hydrogenation reaction

[0055]

[0056] From the results in Table 4, it can be seen that different metal catalysts have different hydrogenation capabilities. Among them, metal Pt and Pd have better activity. When screening solvents, it was found that ethyl acetate and cyclohexane both had good effects, but because ethyl acetate has better solubility, ethyl acetate was used as the hydrogenation solvent. Then the temperature when using ethyl acetate as a solvent for hydrogenation reaction was screened, and it can be concluded that the yield is higher at 120°C, so the optimal conditions for hydrogenation reaction can be obtained.

[0057] The MS spectrum of the hydrogenation product obtained in Example 67 is as follows: Fig. 9 As shown in the GC spectrum Fig.10 As shown. It can be seen from the figure that the maximum mass-to-charge ratio of the molecular ion peak of the substance is m / z=276, while the molecular weight of pinene is 136, and the theoretical molecular weight of the dimerization product is 272. During the hydrogenation process, the addition is mainly to the double bond, and the theoretical molecular weight is 276. Therefore, the product is the target C20 high-density fuel. The gas chromatograph sets the injection port temperature to 280°C, the initial column box temperature to 60°C, the heating rate to 15°C / min, and the temperature is raised to 310°C and maintained for 5 minutes. From the GC graph, it can be seen that the peak with the largest peak area is the peak of the target hydrogenation product, that is, the peak of the target biomass high-density fuel appears around 11 to 15 minutes, which is consistent with the peak time of the precursor generated by isomerization / Diels-Alder.

[0058] The obtained biomass high-density fuel was compared with traditional petroleum-based fuels, and it was found that while maintaining key properties such as density, calorific value, and freezing point, the difficulty and cost of synthesis were greatly reduced.

[0059] Table 5. Comparison of performance of different fuels

[0060]

[0061] As can be seen from the embodiment in Table 5, high-density aviation fuel can be prepared from turpentine by the two-step method. The density of the prepared high-density aviation fuel is 0.935 g / cm 3 , calorific value is 41.9MJ / Kg, freezing point is -55℃; it is an aviation fuel with relatively good performance. The entire route uses biomass as raw material, which is a new green and environmentally friendly route and does not produce harmful substances.

[0062] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for preparing high-density aviation fuel by using Bronsted acid-catalyzed turpentine, characterized in that: The following steps are involved: In the first step, the main terpene compound 1 in turpentine oil undergoes an isomerization reaction under acid catalysis to generate an intermediate with a cyclohexene and cyclohexadiene structure. The intermediate with a cyclohexene and cyclohexadiene structure undergoes a Diels-Alde dimerization addition reaction with itself or with each other under acid catalysis to generate a high-density fuel precursor 2 with a carbon number of 20; In the second step, the generated high-density fuel precursor 2 with a carbon number of 20 is subjected to a hydrogenation reaction under the catalysis of a hydrogenation catalyst to generate a high-density aviation fuel 3; 2. The method for preparing high-density aviation fuel by using Bronsted acid-catalyzed turpentine according to claim 1, characterized in that: In the first step, terpenoid compounds undergo isomerization reaction under the catalysis of an acid catalyst using toluene as solvent.

3. The method for preparing high-density aviation fuel by using Bronsted acid-catalyzed turpentine according to claim 1, characterized in that: In the first step, the acid catalyst is selected from one or more of the following catalysts: H2SO4, p-toluenesulfonic acid, trifluoroacetic acid, acetic acid, Nafion, T-62MP, Amberlyst15, Al-MCM-41-NaAlO2 (Si / Al=60, 40, 20), HPW / SiO2, HPW / MCM-41, D600, CD750, CD250; wherein the ratio of the mass of the acid catalyst to the mass of the reaction substrate is between 0.01 and 0.

5.

4. The method for preparing high-density aviation fuel by using Bronsted acid-catalyzed turpentine according to claim 1, characterized in that: In the first step, when the raw material is pinene, the reaction temperature is 100-160 o C, and the reaction time is between 2-10 h.

5. The method for preparing high-density aviation fuel by using Bronsted acid-catalyzed turpentine according to claim 1, characterized in that: In the first step, the solvent used is selected from propylene carbonate, acetonitrile, toluene, cyclohexane, tetrahydrofuran, dichloromethane, ethyl acetate, N,N - one or more of dimethylformamide, dichloroethane, methanol, isopropanol, the substrate concentration range is 0.01-1 mol / L; the reaction temperature is 100-160 o C, and the reaction time is between 2-10 h.

6. The method for preparing high-density aviation fuel by using Bronsted acid-catalyzed turpentine according to claim 1, characterized in that: In the second step, the hydrogenation catalyst is one of Raney Ni, Raney Co, Pt / C, Pd / C, Ru / C, Ir / C, Rh / C, Co / C, Ni / C, and Fe / C; wherein the ratio of the amount of the catalyst to the mass of the fuel precursor 2 is between 0.01 and 0.

3.

7. The method for preparing high-density aviation fuel by using Bronsted acid-catalyzed turpentine according to claim 1, characterized in that: In the second step, the solvent used is selected from cyclohexane, propylene carbonate, methanol, propanol, isopropanol, tridecane, toluene, tetrahydrofuran, N,N - one or more of dimethylformamide, n-hexane, ethyl acetate, and the substrate concentration range is 0.01-1 mol / L.

8. The method for preparing high-density aviation fuel by using Bronsted acid-catalyzed turpentine according to claim 1, characterized in that: In the second step, the hydrogenation reaction is carried out in a tank reactor at a temperature of 100-200 o C, the reaction time is between 5-10h, and the hydrogen pressure is between 3-5MPa.

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