Compound self-ignition ionic liquid, preparation method and application thereof

Abstract

The application belongs to the technical field of aerospace propellants and energetic materials, and relates to a compounded self-ignition ionic liquid, a preparation method and application. The compounded self-ignition ionic liquid is composed of a self-ignition ionic liquid and a promoter, wherein the self-ignition ionic liquid is cyanoborohydride 1-allyl-3-ethyl imidazole or cyanoborohydride 1-allyl-3-methyl imidazole, and the promoter is 1,3-dimethyl-4,5-diiodo imidazole iodine salt or 1,3-dimethyl-4,5-diiodo imidazole triiodine salt; the self-ignition ionic liquid accounts for 80wt%-95wt%, and the promoter accounts for 5wt%-20wt%. The compounded self-ignition ionic liquid has high density, low viscosity and good thermal stability, and when used in the field of rocket propellants, can achieve good self-ignition effect with H2O2 and fuming nitric acid, and is superior to a single self-ignition ionic liquid.

Description

Technical Field

[0001] This invention belongs to the field of aerospace propellant and energetic materials technology, and relates to a compounded self-igniting ionic liquid, its preparation method and application. Background Technology

[0002] Liquid rocket propellants are liquid substances or combinations of several liquid substances that can undergo exothermic chemical reactions to form high-temperature reaction products. Among them, self-igniting liquid propellants, as a relatively special type of propulsion system, have advantages such as simple structure, high safety and reliability, and re-ignition capability. They play a crucial role in the orbit control and attitude control propulsion systems of spacecraft and have become a frontier and key development direction in aerospace propulsion system research.

[0003] Spontaneous combustion propellants consist of an oxidizer and a fuel. The fuel is typically hydrazine or its derivatives, while the oxidizer is HNO3, N2O4, etc. These substances have drawbacks such as high volatility, strong toxicity, and strong corrosiveness, increasing the difficulty of propellant handling and safety. Therefore, there is an urgent need to develop new green spontaneous combustion propellant systems to meet the rapid development needs of new spacecraft. Since the first report of spontaneous combustion ionic liquids in 2008, hundreds of such liquids have been synthesized, mainly including dicyandiamide-based, borohydride-rich, hydrazine-based, hypophosphorous acid-based, and cyanoboronhydride-based liquids. Their overall performance is superior to that of the currently used spontaneous combustion propellant, unsymmetrical dimethylhydrazine. Rocket-stage H2O2 (>90%) has characteristics such as low toxicity, low vapor pressure, and environmentally friendly exothermic decomposition products, and is widely used as a green oxidizer for various spontaneous combustion fuels, such as lower fatty alcohols, hydrocarbons, and ethylene glycol ethers. H2O2-ionic liquid spontaneous combustion propellants can achieve both fuel greening and low oxidizer corrosivity, making them a key component in green propellant research.

[0004] In recent years, scholars both domestically and internationally have conducted preliminary studies on the auto-ignition behavior of ionic liquids in H2O2. For example, in 2019, Bhosale et al. studied ionic liquids with cyanoboronium anions ([EMIM][BH3CN] and [AEIM][BH3CN]) and found that their ignition delays were all greater than 1000 ms (Bhosale VK, Jeong J, Kwon S. Ignition of boron-based green hypergolic fuels with hydrogen peroxide [J]. Fuel, 2019, 255:115729.). It has been proven that both boron-rich and thiocyanate-based ionic liquids can auto-ignite with H2O2, but the weak acidity and high latent heat of H2O2 generally result in a relatively long ignition delay time. Summary of the Invention

[0005] To address the technical problem of long ignition delay times in existing technologies involving self-igniting ionic liquids and H2O2, this invention proposes a compound self-igniting ionic liquid, its preparation method, and its applications. This compound self-igniting ionic liquid consists of a self-igniting ionic liquid and a promoter, exhibiting good stability and a high decomposition temperature. The promoter used has good solubility in the self-igniting ionic liquid. Adding the compound self-igniting ionic liquid of this invention enables rapid self-ignition behavior of H2O2-compound self-igniting ionic liquid, with an ignition delay time as low as 55 ms when ignited with H2O2 and as low as 1 ms when ignited with nitric acid.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0007] A compounded self-igniting ionic liquid, comprising a self-igniting ionic liquid and an accelerator; wherein the self-igniting ionic liquid is 1-allyl-3-ethylimidazolium cyanoboronide (IL-1) or 1-allyl-3-methylimidazolium cyanoboronide (IL-2); and the accelerator is 1,3-dimethyl-4,5-diiodoimidazolium iodide (P-1) or 1,3-dimethyl-4,5-diiodoimidazolium triiodide (P-2).

[0008] Preferably, the self-igniting ionic liquid has a mass fraction of 80wt% to 95wt%; and the accelerator has a mass fraction of 5wt% to 20wt%.

[0009] Preferably, the self-igniting ionic liquid has a mass fraction of 80wt%~90wt%; and the accelerator has a mass fraction of 10wt%~20wt%.

[0010] The preparation method of the compounded self-igniting ionic liquid is as follows: the self-igniting ionic liquid is mixed and stirred with an accelerator to obtain the compounded self-igniting ionic liquid. The mixing and stirring conditions are at room temperature.

[0011] In this invention, when the accelerator concentration is too high, under the same conditions, the ignition effect may be worse due to the dissolution effect. When the accelerator concentration is too low, experiments have shown that, under the same conditions, such as the ignition experiment of an ionic liquid with a accelerator content of 2% and 89% H2O2, the ignition delay time is about 1000 ms, which is much greater than the effect when the accelerator content is 20%. Therefore, in the experimental scheme of this invention, the accelerator content is 5wt%~20wt%.

[0012] The application of the aforementioned compounded self-igniting ionic liquid in the field of rocket propellants.

[0013] The method for applying the compounded self-igniting ionic liquid in the field of rocket propellants is as follows: the compounded self-igniting ionic liquid is added dropwise to an oxidant-rich oxidant pool, and after full contact, self-ignition occurs; the oxidant is H2O2.

[0014] The oxidant can also be fuming nitric acid.

[0015] The mass fraction of H2O2 is greater than or equal to 89%.

[0016] The mass fraction of the fuming nitric acid is greater than or equal to 68%.

[0017] When the compounded self-igniting ionic liquid is ignited with H2O2, the ignition delay time is as low as 55ms; when the compounded self-igniting ionic liquid is ignited with fuming nitric acid, the ignition delay time is as low as 1ms.

[0018] The accelerator used in this invention was prepared in the laboratory according to the preparation method of patent CN114276300A. The self-igniting ionic liquid 1-allyl-3-ethylimidazole cyanoboronide (IL-1) or 1-allyl-3-methylimidazole cyanoboronide (IL-2) was prepared in the laboratory, and the preparation method is as follows:

[0019] The preparation method of the self-igniting ionic liquid comprises the following steps:

[0020]

[0021] Step a: Preparation of intermediate bromide salt

[0022] At room temperature, 1-allylimidazolium was added to a reaction flask containing redistilled acetonitrile as solvent. Then, under nitrogen protection, bromoethane or bromomethane was slowly added dropwise. After the addition was complete, the reaction mixture was heated and refluxed using an oil bath and stirring apparatus. After the reaction was complete, the product was washed with ethyl acetate, and excess solvent was removed to obtain 1-allyl-3-ethylimidazolium bromide and 1-allyl-3-methylimidazolium bromide.

[0023] Further, in step a, the molar ratio of 1-allylimidazol to bromomethane and bromoethane is 1:(1.05~1.1); the amount of acetonitrile redistilled per millimole of 1-allylimidazol used in the reaction is 1 mL. After the reaction is complete, the amount of ethyl acetate used per millimole of product is 0.5 mL.

[0024] Furthermore, in step a, the reaction temperature is 70°C, the reflux stirring time is 30-36 h, and the product is washed with ethyl acetate 2-3 times.

[0025] Step b: Preparation and purification of spontaneously combusting ionic liquids

[0026] At room temperature, 1-allyl-3-ethylimidazolium bromide and 1-allyl-3-methylimidazolium bromide were added separately to reaction flasks containing redistilled acetonitrile as solvent. Sodium cyanoborohydride was added in proportion, and the mixture was stirred at room temperature. After the reaction was complete, the NaBr salt was filtered out, and the remaining liquid was rotary evaporated under reduced pressure to obtain a crude ionic liquid. Dichloromethane was added to the crude ionic liquid, and the mixture was refrigerated. It was then filtered, rotary evaporated under reduced pressure, and excess solvent was removed using a vacuum evaporator and liquid nitrogen to obtain the purified auto-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazolium (IL-1) or cyanoborohydride 1-allyl-3-methylimidazolium (IL-2).

[0027] Furthermore, in step b, the molar ratio of 1-allyl-3-ethylimidazolium bromide and 1-allyl-3-methylimidazolium bromide to sodium cyanoboronide is 1:(1.05~1.1); the amount of acetonitrile redistilled from the solvent used per millimole of 1-allyl-3-ethylimidazolium bromide and 1-allyl-3-methylimidazolium bromide in the reaction is 1 mL.

[0028] Furthermore, in step b, the stirring time at room temperature is 12~16h.

[0029] The present invention has the following beneficial effects:

[0030] 1. In the experimental process, this invention calculated the corresponding activation energy data. Based on this data, it was initially concluded that the energy generated after the promoter and ionic liquid combined decreased, thus the reaction proceeded faster. Furthermore, this invention tested the physicochemical properties of the compounded self-igniting ionic liquid, and the results showed that the compounded self-igniting ionic liquid exhibited good physicochemical properties. The density of the compounded self-igniting ionic liquid almost all increased to 1.00 g·cm³. -3 The viscosity is slightly higher than that of the original ionic liquid, the ignition delay time is significantly reduced, and good thermal stability is maintained (the thermal decomposition temperature of the ionic liquid without accelerator is 244℃ or 230℃, while the decomposition temperature of the ionic liquid with accelerator can reach up to 324℃); the specific impulse is calculated using EXPLO5 software, and the density specific impulse of the compound ionic liquid is slightly improved compared with that of the single ionic liquid.

[0031] 2. The compounded self-igniting ionic liquid provided by the present invention improves the ignition performance of self-igniting ionic liquid and H2O2. Without accelerators, the ignition delay times of both auto-igniting ionic liquids and 89% H2O2 were greater than 2000 ms. When the amount of accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide was 5% and the amount of auto-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole was 95%, the ignition delay time decreased to 259 ms. When the amount of accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide was 5% and the amount of ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole was 95%, the ignition delay time decreased to 171 ms. When the amount of accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide was 20% and the amount of ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole was 80%, the ignition delay time decreased to 55 ms. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a photograph of the ignition process in Embodiment 12 of the present invention.

[0034] Figure 2 In Example 3 of this invention, 10% P-1 was added to IL-1. 1 H NMR shift change spectrum ( d 6-DMSO).

[0035] Figure 3 In Example 3 of this invention, 10% P-1 was added to IL-1 and then stored for 30 days. 1 H NMR shift change spectrum ( d 6-DMSO).

[0036] Figure 4 In Example 9 of this invention, 10% P-2 was added to IL-1. 1 H NMR shift change spectrum ( d 6-DMSO).

[0037] Figure 5 In Example 9 of this invention, 10% P-2 was added to IL-1 and then stored for 30 days. 1 H NMR shift change spectrum ( d 6-DMSO). Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] In the following embodiments, "%" means: the mass percentage of the corresponding substance.

[0040] Example 1

[0041] The preparation steps of the compounded self-igniting ionic liquid (5% P-1 + 95% IL-1) are as follows:

[0042] At room temperature, 0.25 g of accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide salt was added to 4.75 g of self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole. A magnetic stir bar was added to the glass bottle, and the mixture was stirred and allowed to stand until the solution became clear, thus obtaining a compound self-igniting ionic liquid containing 5% accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide salt and 95% self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole.

[0043] The application of H2O2 as an oxidant in rocket propellants, using a compounded self-igniting ionic liquid (5% P-1 + 95% IL-1), follows these steps:

[0044] At room temperature, 2 mL of 89% H₂O₂ oxidant was added to an open glass bottle. One drop (40-50 μL) of the compounded self-igniting ionic liquid prepared in this example (containing 5% accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide and 95% self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole) was added to a 2 mL H₂O₂ oxidation pool rich in oxidant. Upon full contact, spontaneous combustion occurred, with a vigorous reaction and bright flame. A high-speed camera recorded the entire ignition experiment at 1000 frames per second, showing an ignition delay time of 259 ms.

[0045] The application of fuming nitric acid as an oxidizer in rocket propellants, combined with a self-igniting ionic liquid (5% P-1 + 95% IL-1), follows these steps:

[0046] At room temperature, fuming nitric acid (WFNA, 65%, 2 mL) was added to an open glass bottle as the oxidant. One drop (40-50 μL) of the compounded self-igniting ionic liquid prepared in Example 1 (containing 5% accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide and 95% self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole) was then dropped into an oxidation pool rich in fuming nitric acid. Upon full contact, spontaneous combustion occurred, with a vigorous reaction and a bright flame. A high-speed camera recorded the entire ignition experiment at 1000 frames per second, showing an ignition delay time of 1 ms.

[0047] Example 2

[0048] The preparation steps of the compounded self-igniting ionic liquid (7% P-1 + 93% IL-1) are as follows:

[0049] At room temperature, 0.35 g of accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide salt was added to 4.65 g of self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole. A magnetic stir bar was added to the glass bottle, and the mixture was stirred and allowed to stand until the solution became clear, thus obtaining a compound self-igniting ionic liquid containing 7% accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide salt and 93% self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole.

[0050] The application of H2O2 as an oxidant in rocket propellants, using a compounded self-igniting ionic liquid (7% P-1 + 93% IL-1), follows these steps:

[0051] At room temperature, 2 mL of 89% H₂O₂ oxidant was added to an open glass bottle. One drop (40-50 μL) of the compounded self-igniting ionic liquid prepared in this example (containing 7% accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide and 93% self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole) was added to a 2 mL H₂O₂ oxidation pool rich in oxidant. Upon full contact, spontaneous combustion occurred, with a vigorous reaction and bright flame. A high-speed camera recorded the entire ignition experiment at 1000 frames per second, showing an ignition delay time of 209 ms.

[0052] The application of fuming nitric acid as an oxidizer in rocket propellants, combined with a self-igniting ionic liquid (7% P-1 + 93% IL-1), follows these steps:

[0053] At room temperature, fuming nitric acid (WFNA, 65%, 2 mL) was added to an open glass bottle as the oxidant. One drop (40-50 μL) of the compounded self-igniting ionic liquid prepared in Example 1 (containing 7% accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide and 93% self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole) was then dropped into an oxidation pool rich in fuming nitric acid. Upon full contact, spontaneous combustion occurred, with a vigorous reaction and a bright flame. A high-speed camera recorded the entire ignition experiment at 1000 frames per second, showing an ignition delay time of 1 ms.

[0054] Example 3

[0055] The preparation of the compounded self-igniting ionic liquid (10% P-1 + 90% IL-1) follows these steps:

[0056] At room temperature, 0.5 g of accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide salt was added to 4.5 g of self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole. A magnetic stir bar was added to the glass bottle, and the mixture was stirred and allowed to stand until the solution became clear, thus obtaining a compound self-igniting ionic liquid containing 10% accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide salt and 90% self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole.

[0057] The application of H2O2 as an oxidant in rocket propellants, using a compounded self-igniting ionic liquid (10% P-1 + 90% IL-1), follows these steps:

[0058] At room temperature, 2 mL of 89% H₂O₂ oxidant was added to an open glass bottle. One drop (40-50 μL) of the compounded self-igniting ionic liquid prepared in this example (containing 10% accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide and 90% self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole) was added to a 2 mL H₂O₂ oxidation pool rich in oxidant. Upon full contact, spontaneous combustion occurred, with a vigorous reaction and bright flame. A high-speed camera recorded the entire ignition experiment at 1000 frames per second, showing an ignition delay time of 135 ms.

[0059] The compound system (i.e., the compounded self-igniting ionic liquid) was placed at room temperature and pressure for more than 30 days. No precipitation was observed with the naked eye. Nuclear magnetic resonance (NMR) tests were performed before and after the placement. Figure 2 and Figure 3 As shown, the results further demonstrate that the compound system remained unchanged. Therefore, this compounded self-igniting ionic liquid exhibits good stability.

[0060] Example 4

[0061] The preparation of the compounded self-igniting ionic liquid (12% P-1 + 88% IL-1) follows these steps:

[0062] At room temperature, 0.6 g of accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide salt was added to 4.4 g of self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole. A magnetic stir bar was added to the glass bottle, and the mixture was stirred and allowed to stand until the solution became clear, thus obtaining a compound self-igniting ionic liquid containing 12% accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide salt and 88% self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole.

[0063] Example 5

[0064] The preparation of the compounded self-igniting ionic liquid (15% P-1 + 85% IL-1) follows these steps:

[0065] At room temperature, 0.75 g of accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide salt was added to 4.25 g of self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole. A magnetic stir bar was added to the glass bottle, and the mixture was stirred and allowed to stand until the solution became clear, thus obtaining a compound self-igniting ionic liquid containing 15% accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide salt and 85% self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole.

[0066] The application of H2O2 as an oxidant in rocket propellants, using a compounded self-igniting ionic liquid (15% P-1 + 85% IL-1), follows these steps:

[0067] At room temperature, 2 mL of 89% H₂O₂ oxidant was added to an open glass bottle. One drop (40-50 μL) of the compounded self-igniting ionic liquid prepared in this example (containing 15% accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide and 85% self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole) was added to a 2 mL H₂O₂ oxidation pool rich in oxidant. Upon full contact, spontaneous combustion occurred, with a vigorous reaction and bright flame. A high-speed camera recorded the entire ignition experiment at 1000 frames per second, showing an ignition delay time of 90 ms.

[0068] Example 6

[0069] The preparation of the compounded self-igniting ionic liquid (20% P-1 + 80% IL-1) follows these steps:

[0070] At room temperature, 1 g of accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide salt was added to 4 g of self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole. A magnetic stir bar was added to the glass bottle, and the mixture was stirred and allowed to stand until the solution became clear, thus obtaining a compound self-igniting ionic liquid containing 20% ​​accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide salt and 80% self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole.

[0071] The application of H2O2 as an oxidant in rocket propellants, using a compounded self-igniting ionic liquid (20% P-1 + 80% IL-1), follows these steps:

[0072] At room temperature, 2 mL of 89% H₂O₂ oxidant was added to an open glass bottle. One drop (40-50 μL) of the compounded self-igniting ionic liquid prepared in this example (containing 20% ​​accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide and 80% self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole) was added to a 2 mL H₂O₂ oxidation pool rich in oxidant. Upon full contact, spontaneous combustion occurred, with a vigorous reaction and bright flame. A high-speed camera recorded the entire ignition experiment at 1000 frames per second, showing an ignition delay time of 130 ms.

[0073] Example 7

[0074] The preparation steps of the compounded self-igniting ionic liquid (5% P-2 + 95% IL-1) are as follows:

[0075] At room temperature, 0.25 g of accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide salt was added to 4.75 g of self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole. A magnetic stir bar was added to the glass bottle, and the mixture was stirred and allowed to stand until the solution became clear, thus obtaining a compound self-igniting ionic liquid containing 5% accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide salt and 95% self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole.

[0076] The application of H2O2 as an oxidant in rocket propellants, using a compounded self-igniting ionic liquid (5% P-2 + 95% IL-1), follows these steps:

[0077] At room temperature, 2 mL of 89% H₂O₂ oxidant was added to an open glass bottle. One drop (40-50 μL) of the compounded self-igniting ionic liquid prepared in this example (containing 5% accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide and 95% self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole) was added to an oxidant-rich H₂O₂ oxidation pool. Upon full contact, spontaneous combustion occurred, with a vigorous reaction and bright flame. A high-speed camera recorded the entire ignition experiment at 1000 frames per second, showing an ignition delay time of 171 ms.

[0078] Example 8

[0079] The preparation of the compounded self-igniting ionic liquid (7% P-2 + 93% IL-1) is as follows:

[0080] At room temperature, 0.35 g of accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide salt was added to 4.65 g of self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole. A magnetic stir bar was added to the glass bottle, and the mixture was stirred and allowed to stand until the solution became clear, thus obtaining a compound self-igniting ionic liquid containing 7% accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide salt and 93% self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole.

[0081] Example 9

[0082] The preparation of the compounded self-igniting ionic liquid (10% P-2 + 90% IL-1) follows these steps:

[0083] At room temperature, 0.5 g of accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide salt was added to 4.5 g of self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole. A magnetic stir bar was added to the glass bottle, and the mixture was stirred and allowed to stand until the solution became clear, thus obtaining a compound self-igniting ionic liquid containing 10% accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide salt and 90% self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole.

[0084] The application of H2O2 as an oxidant in rocket propellants, combined with a self-igniting ionic liquid (10% P-2 + 90% IL-1), follows these steps:

[0085] At room temperature, 2 mL of 89% H₂O₂ oxidant was added to an open glass bottle. One drop (40-50 μL) of the compounded self-igniting ionic liquid prepared in this example (containing 10% accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide and 90% self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole) was added to an oxidant-rich H₂O₂ oxidation pool. Upon full contact, spontaneous combustion occurred, with a vigorous reaction and bright flame. A high-speed camera recorded the entire ignition experiment at 1000 frames per second, showing an ignition delay time of 99 ms.

[0086] The compound system (i.e., the compounded self-igniting ionic liquid) was placed at room temperature and pressure for more than 30 days. No precipitation was observed with the naked eye. Nuclear magnetic resonance (NMR) tests were performed before and after the placement. Figure 4 and Figure 5 As shown, the results further demonstrate that the compound system remained unchanged. Therefore, this compounded self-igniting ionic liquid exhibits good stability.

[0087] Example 11

[0088] The preparation of the compounded self-igniting ionic liquid (12% P-2 + 88% IL-1) follows these steps:

[0089] At room temperature, 0.6 g of accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide salt was added to 4.4 g of self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole. A magnetic stir bar was added to the glass bottle, and the mixture was stirred and allowed to stand until the solution became clear, thus obtaining a compound self-igniting ionic liquid containing 12% accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide salt and 88% self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole.

[0090] Example 12

[0091] The preparation of the compounded self-igniting ionic liquid (15% P-2 + 85% IL-1) follows these steps:

[0092] At room temperature, 0.75 g of accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide salt was added to 4.25 g of self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole. A magnetic stir bar was added to the glass bottle, and the mixture was stirred and allowed to stand until the solution became clear, thus obtaining a compound self-igniting ionic liquid containing 15% accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide salt and 85% self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole.

[0093] The application of H2O2 as an oxidant in rocket propellants, using a compounded self-igniting ionic liquid (15% P-2 + 85% IL-1), follows these steps:

[0094] At room temperature, 2 mL of 89% H₂O₂ oxidant was added to an open glass bottle. One drop (40-50 μL) of the compounded self-igniting ionic liquid prepared in this embodiment (containing 15% accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide and 85% self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole) was added dropwise to an oxidant-rich H₂O₂ oxidation pool. After sufficient contact, spontaneous combustion occurred; the reaction was vigorous, with a bright flame produced. A high-speed camera recorded the entire ignition experiment at 1000 frames per second. The results showed an ignition delay time of 63 ms. Figure 3 As shown.

[0095] Example 13

[0096] The preparation of the compounded self-igniting ionic liquid (20% P-2 + 80% IL-1) follows these steps:

[0097] At room temperature, 1 g of accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide salt was added to 4 g of self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole. A magnetic stir bar was added to the glass bottle, and the mixture was stirred and allowed to stand until the solution became clear, thus obtaining a compound self-igniting ionic liquid containing 20% ​​accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide salt and 80% self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole.

[0098] The application of H2O2 as an oxidant in rocket propellants, using a compounded self-igniting ionic liquid (20% P-2 + 80% IL-1), follows these steps:

[0099] At room temperature, 2 mL of 89% H₂O₂ oxidant was added to an open glass bottle. One drop (40-50 μL) of the compounded self-igniting ionic liquid prepared in this example (containing 20% ​​accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide and 80% self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole) was added dropwise to an oxidant-rich H₂O₂ oxidation chamber. Upon full contact, spontaneous combustion occurred, with a vigorous reaction and bright flame. A high-speed camera recorded the entire ignition experiment at 1000 frames per second, showing an ignition delay time of 55 ms.

[0100] Example 14

[0101] The preparation of the compounded self-igniting ionic liquid (20% P-2 + 80% IL-2) follows these steps:

[0102] At room temperature, 1 g of accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide salt was added to 4 g of self-igniting ionic liquid cyanoborohydride 1-allyl-3-methylimidazole. A magnetic stir bar was added to the glass bottle, and the mixture was stirred and allowed to stand until the solution became clear, thus obtaining a compound self-igniting ionic liquid containing 20% ​​accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide salt and 80% self-igniting ionic liquid cyanoborohydride 1-allyl-3-methylimidazole.

[0103] The application of H2O2 as an oxidant in rocket propellants, combined with a self-igniting ionic liquid (20% P-2 + 80% IL-2), follows these steps:

[0104] At room temperature, 2 mL of 89% H₂O₂ oxidant was added to an open glass bottle. One drop (40-50 μL) of the compounded self-igniting ionic liquid prepared in this example (containing 20% ​​accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide and 80% self-igniting ionic liquid cyanoborohydride 1-allyl-3-methylimidazole) was added to the oxidant-rich H₂O₂ oxidation pool. Upon full contact, spontaneous combustion occurred, with a vigorous reaction and bright flame. A high-speed camera recorded the entire ignition experiment at 1000 frames per second, showing an ignition delay time of 70 ms.

[0105] Example 15

[0106] The preparation of the compounded self-igniting ionic liquid (12% P-2 + 88% IL-2) follows these steps:

[0107] At room temperature, 0.6 g of accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide salt was added to 4.4 g of self-igniting ionic liquid cyanoborohydride 1-allyl-3-methylimidazole. A magnetic stir bar was added to the glass bottle, and the mixture was stirred and allowed to stand until the solution became clear, thus obtaining a compound self-igniting ionic liquid containing 12% accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide salt and 88% self-igniting ionic liquid cyanoborohydride 1-allyl-3-methylimidazole.

[0108] The application of H2O2 as an oxidant in rocket propellants, using a compounded self-igniting ionic liquid (12% P-2 + 88% IL-2), follows these steps:

[0109] At room temperature, 2 mL of 89% H₂O₂ oxidant was added to an open glass bottle. One drop (40-50 μL) of the compounded self-igniting ionic liquid prepared in this example (containing 12% accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide and 88% self-igniting ionic liquid cyanoborohydride 1-allyl-3-methylimidazole) was added to an oxidant-rich H₂O₂ oxidation pool. Upon full contact, spontaneous combustion occurred, with a vigorous reaction and bright flame. A high-speed camera recorded the entire ignition experiment at 1000 frames per second, showing an ignition delay time of 161 ms.

[0110] Comparative Example 1

[0111] The application of the compounded self-igniting ionic liquid (IL-1) without accelerator in rocket propellant in this embodiment is as follows:

[0112] At room temperature, 2 mL of 89% H₂O₂ oxidant was added to an open glass bottle. A single drop (40–50 μL) of the single self-igniting ionic liquid 1-allyl-3-ethylimidazolium cyanoborohydride was added to the oxidant-rich H₂O₂ oxidation chamber. Upon full contact, spontaneous combustion occurred, with a vigorous reaction and bright flame. A high-speed camera recorded the entire ignition experiment at 1000 frames per second, showing an ignition delay time of 2870 ms.

[0113] Comparative Example 2

[0114] The application of the compounded self-igniting ionic liquid (IL-2) without accelerator in rocket propellant in this embodiment is as follows:

[0115] At room temperature, 2 mL of 89% H₂O₂ oxidant was added to an open glass bottle. A single drop (40–50 μL) of the single self-igniting ionic liquid 1-allyl-3-methylimidazolium cyanoborohydride was added to the oxidant-rich H₂O₂ oxidation chamber. Upon full contact, spontaneous combustion occurred, with a vigorous reaction and bright flame. A high-speed camera recorded the entire ignition experiment at 1000 frames per second, showing an ignition delay time of 2575 ms.

[0116] Comparative Example 3

[0117] The preparation steps of the compounded self-igniting ionic liquid (2% P-2 + 98% IL-1) are as follows:

[0118] At room temperature, 0.1 g of accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide salt was added to 4.9 g of self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole. A magnetic stir bar was added to the glass bottle, and the mixture was stirred and allowed to stand until the solution became clear, thus obtaining a compound self-igniting ionic liquid containing 2% accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide salt and 98% self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole.

[0119] At room temperature, oxidant H2O2 (89%, 2 mL) was added to an open glass bottle. The compound self-igniting ionic liquid prepared in this example (containing 2% accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide salt and 98% self-igniting ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole) was added dropwise (40-50 μL) to the oxidant-rich H2O2 oxidation pool. After sufficient contact, self-ignition occurred. A high-speed camera recorded the entire ignition experiment at a speed of 1000 frames per second. The results showed that the ignition delay time was about 1000 ms.

[0120] Comparative Example 4

[0121] The preparation steps of this comparative example of a compounded self-igniting ionic liquid (10% P-2 + 90% 1-butyl-3-methylimidazolium cyanoboronide ([BMIM][BH3CN]) are as follows:

[0122] At room temperature, 0.5 g of accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide salt was added to 4.5 g of self-igniting ionic liquid cyanoborohydride 1-butyl-3-methylimidazole. A magnetic stir bar was added to the glass bottle, and the mixture was stirred and allowed to stand until the solution became clear, thus obtaining a compound self-igniting ionic liquid containing 10% accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide salt and 90% self-igniting ionic liquid cyanoborohydride 1-butyl-3-methylimidazole.

[0123] The application of a compound self-igniting ionic liquid prepared using H2O2 as an oxidant in rocket propellants (a compound self-igniting ionic liquid containing 10% accelerator 1,3-dimethyl-4,5-diiodoimidazolium triiodide salt and 90% self-igniting ionic liquid cyanoborohydride 1-butyl-3-methylimidazolium ([BMIM][BH3CN])) is as follows:

[0124] At room temperature, 89% H₂O₂ (2 mL) was added to an open glass bottle. A compound self-igniting ionic liquid containing 10 wt% accelerator 1,3-dimethyl-4,5-diiodoimidazole triiodide and 90 wt% self-igniting ionic liquid cyanoborohydride 1-butyl-3-methylimidazole ([BMIM][BH₃CN]) was dropped into an oxidant-rich H₂O₂ oxidation chamber. Upon full contact, spontaneous combustion occurred, with a vigorous reaction and bright flame. A high-speed camera recorded the entire ignition experiment at 1000 frames per second, showing an ignition delay time of 451 ms.

[0125] Comparative Example 5

[0126] The preparation steps of this comparative example of a compounded self-igniting ionic liquid (10% P-1 + 90% 1-butyl-3-methylimidazolium cyanoboronide ([BMIM][BH3CN]) are as follows:

[0127] At room temperature, 0.5 g of accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide salt was added to 4.5 g of self-igniting ionic liquid cyanoborohydride 1-butyl-3-methylimidazole. A magnetic stir bar was added to the glass bottle, and the mixture was stirred and allowed to stand until the solution became clear, thus obtaining a compound self-igniting ionic liquid containing 10% accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide salt and 90% self-igniting ionic liquid cyanoborohydride 1-butyl-3-methylimidazole.

[0128] The application of a compounded self-igniting ionic liquid in rocket propellants using H2O2 as an oxidant (a compounded self-igniting ionic liquid containing 10% accelerator 1,3-dimethyl-4,5-diiodoimidazolium iodide and 90% self-igniting ionic liquid cyanoborohydride 1-butyl-3-methylimidazolium ([BMIM][BH3CN])) is as follows:

[0129] At room temperature, 89% H₂O₂ (2 mL) was added to an open glass bottle. A compound self-igniting ionic liquid containing 10 wt% accelerator 1,3-dimethyl-4,5-diiodoimidazolium iodide and 90 wt% self-igniting ionic liquid cyanoborohydride 1-butyl-3-methylimidazolium ([BMIM][BH₃CN]) was then dropped into an oxidant-rich H₂O₂ oxidation chamber. Upon full contact, spontaneous combustion occurred, with a vigorous reaction and bright flame. A high-speed camera recorded the entire ignition experiment at 1000 frames per second, showing an ignition delay time of 730 ms.

[0130] The main purpose of this application's embodiments is to study the ignition effect of green propellants, i.e., when the oxidant is H2O2. The ignition delay time of fuming nitric acid and cyanoborhydride-like ionic liquids is already very fast, less than 1ms, and is only used as a supplementary group.

[0131] For the prepared compounded auto-igniting ionic liquids and single ionic liquids, density, viscosity, and glass transition temperature were measured using a DMA 5000M-Lovis2000ME digital density-viscosity meter and a Swiss Mettler-Toledo DSC1 differential scanning calorimeter; Gaussian 09 was used to calculate the enthalpy of formation, and EXPLO5 software was used to calculate the specific impulse. The calculation results are shown in the table below: ( [a] Density at 25℃; [b] Viscocity at 25℃; [c] :decompositiontemperature; [d] : melting temperature; [e] :specific impulse; [f] : oxidizer to fuel ratio at maximum specific impact; [g] (ignition delay time)

[0132] Table 1. Physicochemical properties of the self-igniting ionic liquid before and after compounding.

[0133]

[0134] Note: fuel: fuel

[0135] ρ density at 25 o C (density of the system at 25 °C)

[0136] η viscocity at 25 o C (viscosity of the system at 25 °C)

[0137] T p Decomposition temperature

[0138] T m Melting temperature

[0139] I sp Specific impulse

[0140] O / F: Oxidizer to fuel ratio at maximum specific impact (the ratio of oxidizer to fuel at maximum specific impulse)

[0141] ρI sp Density specific impulse

[0142] IDT: Ignition Delay Time

[0143] Oxidizer: Oxidizing agent

[0144] Table 1 shows that, in Comparative Examples 1 and 2, without the addition of an accelerator, the ignition delay times of both auto-igniting ionic liquids and 89% H2O2 were greater than 2000 ms. When the amount of accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide was 5% and the amount of ionic liquid cyanoborohydride 1-allyl-3-ethylimidazole was 95% (i.e., 5% P-1 + 95% IL-1), the ignition delay time decreased to 259 ms; when the amount of accelerator 1,3-dimethyl-4,5-diiodoimidazole iodide was 5%, the ignition delay time decreased to 259 ms. When the addition of 5% diiodoimidazole triiodide salt and 95% cyanoborohydride 1-allyl-3-ethylimidazole ionic liquid (i.e., 5% P-2 + 95% IL-1) reduces the ignition delay time to 171 ms; when the addition of 20% 1,3-dimethyl-4,5-diiodoimidazole triiodide salt accelerator and 80% cyanoborohydride 1-allyl-3-ethylimidazole ionic liquid (i.e., 20% P-2 + 80% IL-1) ignition delay time reduces to 55 ms. Therefore, after adding the compound self-igniting ionic liquid of the present invention, rapid self-ignition behavior of H2O2 / compound self-igniting ionic liquid can be achieved, with an ignition delay time as low as 55 ms when the accelerator addition is 20%.

[0145] The compounded self-igniting ionic liquid of this invention exhibits excellent physicochemical properties. The density of the compounded self-igniting ionic liquid is almost always increased to 1.00 g·cm³ compared to the self-igniting ionic liquid. -3 The viscosity increased with increasing accelerator dosage, while the ignition delay time decreased significantly. Simultaneously, good stability was maintained (no precipitation was observed visually after the compound system was placed at room temperature and pressure for over 30 days; NMR and IR tests further confirmed that the compound system remained unchanged) and thermal stability (the thermal decomposition temperature of the ionic liquid without accelerator was 244℃ or 230℃, while the ionic liquid with accelerator reached a maximum decomposition temperature of 324℃). Specific impulse calculations using EXPLO5 software showed that the density specific impulse of the compound ionic liquid was slightly higher than that of the single ionic liquid.

[0146] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A compounded self-igniting ionic liquid, characterized in that: The compounded self-igniting ionic liquid is composed of a self-igniting ionic liquid and an accelerator; the self-igniting ionic liquid is 1-allyl-3-ethylimidazolium cyanoboronide or 1-allyl-3-methylimidazolium cyanoboronide; the accelerator is 1,3-dimethyl-4,5-diiodoimidazolium iodide or 1,3-dimethyl-4,5-diiodoimidazolium triiodide; the mass fraction of the self-igniting ionic liquid is 80wt%~90wt%; the mass fraction of the accelerator is 10wt%~20wt%.

2. The method for preparing the compounded self-igniting ionic liquid according to claim 1, characterized in that: The self-igniting ionic liquid was mixed and stirred with an accelerator at room temperature to dissolve, resulting in a compounded self-igniting ionic liquid.

3. The application of the compounded self-igniting ionic liquid as described in claim 1 in the field of rocket propellants.

4. The application according to claim 3, characterized in that: The compounded self-igniting ionic liquid is added dropwise to an oxidant-rich oxidant pool, and after full contact, spontaneous combustion occurs.

5. The application according to claim 4, characterized in that: The oxidant is H2O2.

6. The application according to claim 4, characterized in that: The oxidant is fuming nitric acid.

7. The application according to claim 5, characterized in that: The mass fraction of H2O2 is greater than or equal to 89%.

8. The application according to claim 6, characterized in that: The mass fraction of the fuming nitric acid is greater than or equal to 68%.

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