CN106190344B - A kind of method and its fuel for preparing the compound hydrocarbon fuel of high energy - Google Patents

Abstract

The invention discloses a method for preparing high-energy composite hydrocarbon fuel and the fuel thereof. The silane coupling agent is dissolved in a mixed solvent and hydrolyzed at a certain temperature for a certain period of time; the hydrolyzed silane coupling agent is added dropwise to the suspension composed of nano boron powder and mixed solvent, and reacted for a certain period of time at a certain temperature to make the nano Hydrophobic groups are introduced into the surface of the boron powder; the surface-modified nano-boron powder is added to the hydrocarbon fuel, and ultrasonically dispersed to obtain a uniformly dispersed high-energy composite hydrocarbon fuel. The invention is used to improve the energy density of different types of hydrocarbon fuels, and the prepared fuel has higher weight and volume combustion calorific value, can be used as high-energy fuel for aviation or aerospace engines, and has good application prospects.

Description

A method for preparing high-energy composite hydrocarbon fuel and its fuel

technical field

The invention belongs to a method for preparing high-energy fuel, and in particular relates to a method for preparing high-energy composite hydrocarbon fuel and the fuel thereof.

Background technique

Hydrocarbon fuels such as aviation kerosene and rocket kerosene have been used in aerospace engines, and have the advantages of non-toxicity and high combustion calorific value. With the development of large launch vehicles and hypersonic vehicles, higher requirements are placed on the energy density of fuels, and the existing hydrocarbon fuels can no longer meet these requirements.

There are usually two ways to increase the energy density of fuels: one is to directly synthesize high-energy fuels through chemical methods; the other is to add high-energy substances, such as aluminum, magnesium, and boron, to the fuels. Chemical synthesis method is an important way to obtain new high-energy fuels, but it often has disadvantages such as low synthesis yield and high cost, and the synthesized fuels are difficult to be applied on a large scale. Adding high-energy substances to fuel is currently the most effective and simple way to increase the energy density of fuel.

Elemental boron has a high combustion calorific value, and its weight combustion calorific value is about 59kJ/g, second only to hydrogen and beryllium, but the density of hydrogen fuel is very small, and the combustion products of beryllium are highly toxic. The volumetric combustion calorific value of elemental boron is about 140kJ/cm ³ , which is the highest among all elements, 1.7 times and 3.2 times that of metal aluminum (83.6kJ/cm ³ ) and magnesium (43.7kJ/cm ³ ), so elemental boron Boron is the most ideal high-energy additive to increase the energy density of hydrocarbon fuels. Unfortunately, due to the poor compatibility of elemental boron with hydrocarbon fuels, it is impossible to obtain stable high-energy composite fuels by directly adding elemental boron to hydrocarbon fuels.

Analyzing published patents and documents, it is found that surface hydrophobized nano boron has better dispersion stability in hydrocarbon fuels, which is beneficial to the preparation of high-energy composite hydrocarbon fuels.

In 2007, Pickering et al. from the University of California, Davis reported a method for directly synthesizing surface-functionalized nano-elemental boron by liquid phase reduction (AL Pickering, C Mitterbauer, ND Browing et al. Chem.Commun.2007, 580-582). The basic principle of the method is: in anhydrous di(methoxy)ethane solvent, reduce boron tribromide (BBr ₃ ) with naphthyl sodium to obtain nanometer elemental boron whose surface is covered by bromine atoms, and the latter is combined with Excessive higher aliphatic alcohols (such as octanol) react to obtain surface-hydrophobized nanometer elemental boron. The method uses boron tribromide as a raw material to directly synthesize surface-hydrophobized nanometer elemental boron, which has the advantages of easy-to-obtain raw materials and simple process, but the reaction yield is very low. Whether these surface-functionalized nano-boron powders are easy to disperse in hydrocarbon fuels is not reported in this paper.

In 2009, Bellott et al. from the University of Illinois at Urbana-Champaign in the United States used decaborane (B ₁₀ H ₁₄ ) as a raw material to obtain a diameter of 10-150nm through steam pyrolysis (700-900°C). Crystalline elemental boron with oxides (BJ Bellott, W Noh, RG Nuzzo et al. Chem. Commun. 2009, 3214-3215). According to reports, the nanometer boron prepared by this method is easy to disperse in organic solvents such as toluene and pentane, but it settles after a few hours. Bellott et al. also discussed the surface functionalization of nano-boron powder, and found that the product obtained after the reaction of nano-elemental boron with Br ₂ (benzene as solvent) or XeF ₂ (benzene as solvent), that is, surface brominated or fluorinated nano-boron Powder needs to be oxidized at a higher temperature. As for whether the surface-modified nano-boron powder is easy to disperse in hydrocarbon fuels, this paper does not report.

In 2009, Anderson et al. of Utah University in the U.S. used high-energy ball milling to prepare nano boron powder (B V Devener, J P L Perez, S L Anderson. Journal of Materials Research, 2009, 24 (11): 3462-3464 without oxide on the surface. ). Typical operating conditions are: under nitrogen protection, 2g of original boron powder (average size 800nm) is mixed with 15mL of n-hexane, then 1mL of oleic acid is added, mixed evenly and then ball milled. It is reported that the nano-boron powder prepared by this method has better dispersibility in hydrocarbon fuels (no specific experimental results are given), but if oleic acid is not added during ball milling, the obtained nano-boron powder has a good dispersion in hydrocarbon fuels. The reason for this is that oleic acid is added during the ball milling process, and when the large-particle boron powder is ground into small-particle boron powder, a layer of oleic acid molecules will be coated on the surface of the small-particle boron powder. protective film. This protective film prevents boron from being oxidized and also facilitates dispersion in organic solvents or hydrocarbon fuels. Although the nano-boron powder prepared by the ball milling method has many advantages, it usually contains more impurities. The jars and balls used for ball milling are generally made of tungsten carbide, whose hardness is equivalent to that of boron. Therefore, during the ball milling process, not only the boron particles are ground, but also the tungsten carbide is also worn out, which is mixed with boron as impurities and is difficult to separate. .

In 2015, Zhang Xiangwen's research group at Tianjin University reported a method for uniformly dispersing nano boron powder in JP-10 hydrocarbon fuel (X E, X Zhi, Y Zhang et al. Chemical Engineering Science, 2015,129:9-13 ). The principle of the method is: using nanometer elemental boron as a raw material, using intermolecular interactions to coat a layer of protective ligands on the surface of nanometer boron powder to increase its dispersibility in hydrocarbon fuels. They tested several ligands such as oleylamine, oleic acid, dodecyl mercaptan, dodecyl nitrile, tri-n-octyl phosphate (TOP), tri-n-octyl phosphine oxide (TOPO), and triphenyl phosphate (TPP). The coating effect of TOPO was found to be the best. TOPO-modified nano-boron powder can be uniformly dispersed in JP-10 hydrocarbon fuel with certain stability, but the reproducibility of this method is poor.

Contents of the invention

The object of the present invention is to provide a method for preparing high-energy composite hydrocarbon fuel and its fuel. The method is applicable to the preparation of different types of hydrocarbon fuels and has the advantages of simple process, low cost and high yield.

The purpose of the present invention is achieved through the technical solution of the following steps:

One, a kind of method for preparing high-energy composite hydrocarbon fuel:

1) Hydrolysis of the silane coupling agent: the silane coupling agent is dissolved in a mixed solvent and hydrolyzed for a certain period of time at a certain temperature;

2) Surface chemical modification of nano-boron powder: Weigh nano-boron powder and disperse it in a mixed solvent, then add dropwise the silane coupling agent after the first step of hydrolysis, and react at a certain temperature for several hours to obtain surface-hydrophobized nano-boron powder ;

3) Preparation of high-energy composite hydrocarbon fuel: adding the surface-modified nano-boron powder into liquid hydrocarbon fuel, and ultrasonically dispersing for 5-30 minutes to obtain a uniformly dispersed high-energy composite hydrocarbon fuel.

In the step 1), the hydrolysis temperature is 25-75° C., and the hydrolysis time is 0.5-12 hours.

The reaction temperature in the step 2) is 50-120°C, and the reaction time is 1-12h.

The step 2) is to dissolve the nano-boron powder in the mixed solvent of alcohol and water, disperse it ultrasonically, stir and heat it to 50-120°C under nitrogen atmosphere, add the hydrolyzed silane coupling agent solution, and react for 1-12 hours , suction filtration, the method of washing the solid with alcohol-water mixed solvent, and suction filtration was repeated three times, and dried in a constant temperature environment to obtain surface-modified nano-boron powder.

The mass ratio of the silane coupling agent to the nano boron powder in the step 2) is 0.50:1˜1.25:1.

The silane coupling agent in the step 1) is n-octyltrimethoxysilane, n-octyltriethoxysilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, dodecane Trimethoxysilane, Dodecyltriethoxysilane, Tetradecyltrimethoxysilane, Tetradecyltriethoxysilane, Hexadecyltrimethoxysilane, Hexadecyltriethoxysilane silane, octadecyltrimethoxysilane, octadecyltriethoxysilane, etc.

The mixed solvent in the step 1) is formed by mixing an organic solvent of methanol, ethanol, 1-propanol or 2-propanol with pure water in proportion, and the volume percentage of pure water in the mixed solvent is 10-90%. .

The hydrocarbon fuel in the described step 3) includes aviation kerosene, rocket kerosene, JP-10, decahydronaphthalene and the like.

The content of the nano boron powder in the said step 3) in the hydrocarbon fuel is not higher than 30wt%.

2. A high-energy composite hydrocarbon fuel is prepared by the above-mentioned method.

The mechanism of silane coupling agent to modify nano-boron powder is: after hydrolysis, the hydroxyl group in the silane coupling agent reacts with the surface of boron, and the hydrophobic long carbon chain in the silane coupling agent coats the surface of boron particles. On the one hand, it can Inhibiting the agglomeration between nano-boron powders, on the other hand, enhances the hydrophobicity of the surface of boron particles, thereby improving the compatibility between nano-boron powders and hydrocarbon fuels, and is conducive to obtaining uniform and stable high-energy fuels.

The beneficial effect that the present invention has compared with background technology is:

The invention uses a silane coupling agent to modify the surface of the nano-boron powder, and the modified boron powder is easily dispersed in hydrocarbon fuels such as decahydronaphthalene, and has good stability and reproducibility.

Adding boron powder modified with silane coupling agent to the hydrocarbon fuel of the present invention can increase the energy density of different types of hydrocarbon fuels, and the fuel produced has a higher weight and volume calorific value of combustion, and can be used as a fuel for aviation or spaceflight. The use of high-energy fuel for the engine, specifically for the use of engine fuel for large launch vehicles and hypersonic vehicles, has good application prospects and value.

Description of drawings

Fig. 1 is the photo of the original nano-boron powder, the nano-boron powder prepared according to the comparative example of the prior art and the nano-boron powder prepared in Example 1 of the present invention dispersed in decahydronaphthalene fuel. Among the figures: A represents the original nano-boron powder; B represents the nano-boron powder prepared in the comparative example; C represents the nano-boron powder prepared in Example 1 of the present invention.

Fig. 2 is a photo of nano-boron powder prepared in the embodiment of the present invention dispersed in different types of hydrocarbon fuels. In the figure: A represents JP-10 fuel; B represents aviation kerosene.

detailed description

The present invention will be further described below in conjunction with drawings and embodiments.

Embodiments of the present invention are as follows:

Comparative example (by the method that people such as Zhang Xiangwen proposes)

Weigh 1.00g of original nano-boron powder and 1.00g of tri-n-octylphosphine oxide (TOPO), add it to 15mL of decahydronaphthalene, ultrasonically disperse for 5min, heat up to 190°C under nitrogen atmosphere, stir for 6h, filter with suction, use for solid The decahydronaphthalene is ultrasonically dispersed, filtered with suction, washed three times in this way, and finally the boron powder is dried in an oven at 60°C.

Add a certain amount of nano-boron powder modified by the above method (the content of B is 1wt%) in the decahydronaphthalene fuel, and leave it standing after ultrasonic dispersion for 5 minutes. After 4 hours, obvious sedimentation occurs. After 24 hours, the upper layer solution becomes clear. (As shown in Figure 1).

Embodiment 1 of the present invention

Weigh 1.00 g of hexadecyltrimethoxysilane, dissolve it in 30 mL of methanol-water mixed solvent (volume ratio 2:1), stir and hydrolyze at 25° C. for 3 h.

Add 1.00g of original nano-boron powder and 30mL of methanol-water mixed solvent (volume ratio 2:1) into a three-necked flask, ultrasonically disperse for 5min, stir and heat to 70°C under nitrogen atmosphere, then add the above hydrolyzed silane coupling agent dropwise The solution was reacted for 3 hours, filtered with suction, the solid was washed with methanol-water mixed solvent, and then filtered with suction, and the washing was repeated three times in this way, and finally the boron powder was dried in an oven at 60°C.

Add the nano-boron powder modified by the above method (the content of B is 1wt%) in the decahydronaphthalene fuel, and let it stand after ultrasonic dispersion for 5 minutes. After 24 hours, the system is still very uniform, and no sedimentation occurs (as shown in Figure 1) . It can be seen that the nano-boron powder prepared by the present invention can be uniformly dispersed in decahydronaphthalene, and its stability is far better than that of the nano-boron powder prepared by the comparative example.

Embodiment 2 of the present invention

Weigh 1.00 g of n-octyltrimethoxysilane, dissolve it in 30 mL of methanol-water mixed solvent (volume ratio 2:1), and stir and hydrolyze at 25° C. for 12 h.

Add 1.00g of original nano-boron powder and 30mL of methanol-water mixed solvent (volume ratio 2:1) into a three-neck flask, ultrasonically disperse for 15min, stir and heat to 80°C under a nitrogen atmosphere, then add the above-mentioned hydrolyzed silane coupling agent dropwise The solution was reacted for 6 hours, filtered with suction, the solid was washed with methanol-water mixed solvent, and then filtered with suction, and the washing was repeated three times in this way, and finally the boron powder was dried in an oven at 60°C.

Add the nano-boron powder modified by the above method (the content of B is 10wt%) to the decahydronaphthalene fuel, ultrasonically disperse it for 5 minutes and let it stand still. After 24 hours, the system is still very uniform without sedimentation.

Embodiment 3 of the present invention

Weigh 1.00g of octadecyltriethoxysilane, dissolve it in 30mL of ethanol-water mixed solvent (volume ratio 2:1), and stir and hydrolyze at 55°C for 12h.

Add 1.00g of original nano-boron powder and 30mL of ethanol-water mixed solvent (volume ratio 2:1) into the three-necked flask, ultrasonically disperse for 10min, stir and heat to 90°C under nitrogen atmosphere, then add dropwise the hydrolyzed silane coupling agent solution , react for 12 hours, filter with suction, wash the solid with ethanol-water mixed solvent, and filter with suction again, repeat the washing three times in this way, and finally put the boron powder in an oven at 60°C to dry.

Add the nano-boron powder modified by the above method (the content of B is 10wt%) to the JP-10 fuel, ultrasonically disperse it for 5 minutes and let it stand. After 24 hours, the system is still very uniform without sedimentation (as shown in Figure 2) .

Embodiment 4 of the present invention

Weigh 1.00g of dodecyltriethoxysilane, dissolve it in 30mL of 2-propanol-water mixed solvent (volume ratio 2:1), stir and hydrolyze at 75°C for 8h.

Add 1.00g of original nano-boron powder and 30mL of 2-propanol-water mixed solvent (volume ratio 2:1) into the three-necked flask, ultrasonically disperse for 10min, stir and heat to 80°C under nitrogen atmosphere, then dropwise add the above-mentioned hydrolyzed silane coupling solution, reacted for 10 hours, filtered with suction, washed the solid with a mixed solvent of 2-propanol-water, and filtered with suction again, repeated washing in this way three times, and finally dried the boron powder in an oven at 60°C.

Add the nano-boron powder modified by the above method (the content of B is 10wt%) to the aviation kerosene, ultrasonically disperse it for 5 minutes and let it stand. After 24 hours, the system is still very uniform without sedimentation (as shown in Figure 2).

Embodiment 5 of the present invention

Weigh 1.00 g of n-octyltriethoxysilane, dissolve it in 30 mL of 1-propanol-water mixed solvent (volume ratio 2:1), stir and hydrolyze at 45°C for 10 h.

Add 1.00g of original nano-boron powder and 30mL of 1-propanol-water mixed solvent (volume ratio 2:1) into a three-necked flask, ultrasonically disperse for 5min, stir and heat to 100°C under nitrogen atmosphere, then add dropwise the hydrolyzed silane distillate The joint agent solution was reacted for 8 hours, filtered with suction, and the solid was washed with a mixed solvent of 1-propanol-water, and then filtered with suction, and the washing was repeated three times in this way, and finally the boron powder was dried in an oven at 60°C.

Add the nano-boron powder modified by the above method (the content of B is 30wt%) to the decahydronaphthalene fuel, ultrasonically disperse it for 30 minutes and let it stand still. After 24 hours, the system is still very uniform without sedimentation.

Compared with the comparative examples by the above examples, the existing method cannot obtain stable high-energy hydrocarbon fuels with boron powder added, and adopts the preparation method of the present invention, it is easy to obtain the high-energy composite carbon with boron powder added uniformly dispersed The hydrogen fuel, the nano-boron powder modified by the technology of the present invention, can be used as a high-energy additive for different types of hydrocarbon fuels, and the obtained high-energy composite hydrocarbon fuel has good uniformity and stability.

The embodiments in the above-mentioned specific embodiments are used to illustrate the present invention, rather than to limit the present invention, within the spirit of the present invention and the scope of protection of the claims, any amendments and changes made to the present invention all fall within the scope of the present invention. protected range.

Claims (7)

1. A method for preparing high-energy composite hydrocarbon fuel, characterized in that it may further comprise the steps: 1) Hydrolysis of the silane coupling agent: the silane coupling agent is dissolved in a mixed solvent and hydrolyzed for a certain period of time at a certain temperature; 2) Surface chemical modification of nano-boron powder: Weigh nano-boron powder and disperse it in a mixed solvent, then add dropwise the silane coupling agent after the first step of hydrolysis, and react at a certain temperature for several hours to obtain surface-hydrophobized nano-boron powder ; 3) Preparation of high-energy composite hydrocarbon fuel: add surface-modified nano-boron powder to hydrocarbon fuel, and disperse ultrasonically for 5-30 minutes to obtain a uniformly dispersed high-energy composite hydrocarbon fuel; The mixed solvent in the step 1) is formed by mixing organic solvents such as methanol, ethanol, 1-propanol or 2-propanol and pure water in proportion, and the volume percentage of pure water in the mixed solvent is 10-90% %; the hydrolysis temperature is 25-75°C, and the hydrolysis time is 0.5-12h; The reaction temperature in the step 2) is 50-120°C, and the reaction time is 1-12h. 2. A kind of method for preparing high-energy composite hydrocarbon fuel according to claim 1, is characterized in that: described step 2) is specifically that nano-boron powder is dissolved in the mixed solvent of alcohol and water, ultrasonically dispersed, and then in nitrogen gas Stir and heat to 50-120°C under the atmosphere, add the hydrolyzed silane coupling agent solution, react for 1-12 hours, filter with suction, wash the solid with a mixed solvent of alcohol and water, and then filter with suction for three times, and place in a constant temperature environment Dry in medium to obtain the surface-modified nano-boron powder. 3. A method for preparing high-energy composite hydrocarbon fuel according to claim 2, characterized in that: the mass ratio of silane coupling agent and nano-boron powder in said step 2) is 0.50:1～1.25:1 . 4. a kind of method for preparing high-energy composite hydrocarbon fuel according to claim 1 is characterized in that: the silane coupling agent in the described step 1) is n-octyltrimethoxysilane, n-octyltriethylsilane Oxysilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, dodecyltrimethoxysilane, dodecyltriethoxysilane, tetradecyltrimethoxysilane, Tetraalkyltriethoxysilane, Hexadecyltrimethoxysilane, Hexadecyltriethoxysilane, Octadecyltrimethoxysilane, Octadecyltriethoxysilane. 5. A method for preparing high-energy composite hydrocarbon fuel according to claim 1, characterized in that: the hydrocarbon fuel in the described step 3) comprises aviation kerosene, rocket kerosene, JP-10, and decahydronaphthalene. 6. A method for preparing high-energy composite hydrocarbon fuel according to claim 1, characterized in that: the content of nano-boron powder in the hydrocarbon fuel in the step 3) is not higher than 30wt%. 7. A high-energy composite hydrocarbon fuel, characterized in that it is prepared by any one of the methods described in claims 1-6.