Method for efficiently synthesizing CL-20 high-energy cage compound based on supported palladium hydroxide catalyst
By using a palladium hydroxide catalyst supported by TiO2(B) nanosheets, the problem of high production cost of CL-20 was solved, and an efficient and low-cost catalytic hydrobenzyl reaction was achieved to prepare a high-purity CL-20, which is suitable for the large-scale production of military energy-containing materials.
Patent Information
- Application Number
- CN202510401571.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-01
- Publication Date
- 2025-07-11
AI Technical Summary
In the prior art, the production cost of CL-20 is high, the traditional palladium catalyst has low dispersion and insufficient atomic utilization rate, resulting in limited reaction efficiency and increased by-products, making it difficult to achieve large-scale mass production.
TiO2(B) nanosheets were used as support to support palladium hydroxide to form a catalyst. Hexabenzylhexazaisowoodsane was converted into tetraacetyldibenzylhexazaisowoodsane and tetraacetylhexazaisowoodsane intermediates by two-step catalytic hydrodebenzylhexazaisowoodsane intermediates, and then CL-20 was prepared by nitration reaction. The palladium atomic dispersion of the catalyst was atomic order and the loading was ≤5 wt%.
The palladium usage is significantly reduced by 50%, the catalytic efficiency is improved, and the yield of catalytic hydrodebenzylacetylation products reaches 93%, and the purity is higher than 99.5%, which is suitable for large-scale production in high-value-added fields.
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Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of chemical synthesis, and in particular to a method for efficiently synthesizing CL-20 high-energy cage compounds based on a supported palladium hydroxide catalyst. Background Art
[0002] As the current single-component energetic material with the best comprehensive performance, CL-20 (hexanitrohexaazaisowurtzitane) has irreplaceable strategic value in the fields of national defense, military industry, aerospace and high-energy propellants due to its high energy density (2.04 g·cm -3 ), ultra-high detonation velocity (9580 m·s -1 ), and detonation pressure (45.2 GPa). However, its industrial application has long been limited by high production costs, and the key bottleneck is concentrated in the debenzylation process. Traditional production processes require the use of precious metal palladium catalysts (such as Pd / C, with a palladium loading of 10 wt.%) to catalyze the debenzylation reaction, and this step accounts for more than 50% of the total cost. In addition, the existing palladium catalysts in the prior art have problems such as low dispersion and insufficient atomic utilization rate, resulting in limited reaction efficiency and increased by-products, further exacerbating resource waste and economic burden.
[0003] In recent years, although researchers have tried to reduce costs by optimizing reaction conditions or improving catalyst supports (such as activated carbon, metal oxides), the amount of palladium used is still difficult to significantly reduce, and the interfacial compatibility between the support and the active component is insufficient, easily leading to agglomeration and inactivation of palladium particles. At the same time, the traditional process has strict requirements for solvent purity, reaction temperature and pressure, and large-scale production faces challenges such as high energy consumption and complex operation. In this context, the development of a new catalytic system with high activity, high stability and low precious metal consumption has become the core direction to break through the industrialization bottleneck of CL-20. Summary of the Invention
[0004] In order to achieve the above object, the present invention provides a method for efficiently synthesizing CL-20 high-energy cage compounds based on a supported palladium hydroxide catalyst, which solves the technical problems such as the overly expensive production cost of CL-20 and the inability to be mass-produced and applied on a large scale.
[0005] The present invention provides a method for efficiently synthesizing CL-20 high-energy cage compounds based on a supported palladium hydroxide catalyst, comprising the following steps: using TiO2(B) nanosheets as a support, loading palladium hydroxide to form a catalyst, and successively converting hexabenzylhexaazaisowurtzitane (HBIW) into tetraacetyl dibenzylhexaazaisowurtzitane (TADBIW) and tetraacetylhexaazaisowurtzitane (TAIW) intermediates through two-step catalytic hydrogenation debenzylation, and then converting TAIW into CL-20 through a nitration reaction.
[0006] Further, the preparation method of the catalyst comprises the following steps:
[0007] a) Mix a titanium source with an alcohol solvent and react to generate a TiO2(B) precursor;
[0008] b) Treat the precursor by hydrothermal method at 100 - 200 °C to form ultrathin TiO2(B) nanosheets;
[0009] c) Mix a palladium salt solution with the TiO2(B) nanosheets, adjust the pH to alkaline conditions so that palladium is deposited on the surface of the nanosheets in the form of palladium hydroxide to obtain a supported palladium hydroxide catalyst.
[0010] Furthermore, the TiO2(B) nanosheets have an open channel structure.
[0011] Furthermore, the 010 crystal plane of the TiO2(B) nanosheets is preferentially exposed.
[0012] Furthermore, the palladium atomic dispersion of the catalyst is at the atomic level and the loading amount ≤ 5 wt%.
[0013] Furthermore, the dispersion of the palladium hydroxide is at the atomic level, and the high-exposure active sites of palladium atoms are realized through the open channel structure of the support, and the palladium loading amount is 0.1% - 5 wt%.
[0014] Furthermore, in the preparation of the catalyst, the titanium source is TiCl4 or titanate, and the alcohol solvent is ethylene glycol, propylene glycol or glycerol; after the hydrogenation reaction, the intermediates of tetraacetyldibenzylhexanitroisowurtzitane (TADBIW) and tetraacetylhexanitroisowurtzitane (TAIW) are purified by organic solvent extraction, and the organic solvent is dimethyl sulfoxide, N,N-dimethylformamide or acetone.
[0015] Furthermore, in the catalytic hydrogenation debenzylation, the amount of palladium used is 0.1% - 1% of the mass of the substrate HBIW, the reaction temperature is 20 - 80 °C, and the reaction time is 8 - 24 hours; the hydrogenation reaction is carried out in two stages: the first stage reacts at room temperature for 2 - 4 hours, and the second stage is heated to 40 - 60 °C and reacts for 6 - 20 hours.
[0016] Furthermore, in step b), the hydrothermal reaction temperature is 120 - 180 °C, the reaction time is 2 - 6 hours, the thickness of the generated TiO2(B) nanosheets ≤ 5 nm, and the lateral size is 50 - 200 nm.
[0017] Furthermore, in step c), the palladium salt is PdCl2, Pd(NO3)2 or Pd(OAc)2, the pH is adjusted to 10 - 14, and Pd is 2+ converted to Pd(OH)2 deposition through alkaline conditions.
[0018] The method for efficiently synthesizing high-energy cage compound CL-20 based on supported palladium hydroxide catalyst proposed by the present invention has the following beneficial effects:
[0019] 1. The present invention adopts the strategy of supported palladium hydroxide catalyst to participate in the catalytic synthesis of high-energy cage compound CL-20. The TiO2-supported palladium hydroxide catalyst is macroscopically prepared by the impregnation deposition method. Further, due to the high-activity catalytic interface and high atomic utilization rate of the catalyst, the cage-shaped CL-20 is successfully and efficiently prepared. The yield of the catalytic hydrogenation debenzylation acetylation product reaches 93%, and the Pd usage is reduced by 50%. It can greatly reduce the production cost, improve the synthesis efficiency, and is beneficial to large-scale production and application.
[0020] 2. Through carrier innovation (TiO2(B) nanosheets) and atomic-level dispersion technology, the dispersion bottleneck of traditional activated carbon-supported catalysts is broken through, and the catalytic efficiency is significantly improved. By using atomic-level dispersion + open channel structure, high yield (93%) and high selectivity are achieved, which is applicable to high-value-added fields (such as military energetic materials) with strict requirements for product yield and purity. Description of the Drawings
[0021] Figure 1 It is the test spectrum of Example 1;
[0022] Figure 2 It is the 1H NMR spectrum of the TADBIW intermediate;
[0023] Figure 3 It is the high-resolution mass spectrum of CL-20;
[0024] Figure 4 It is the scanning electron microscope spectrum of CL-20. Detailed Embodiments
[0025] The following specific examples illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.
[0026] Unless otherwise specified, the examples and comparative examples are parallel tests with the same components, component contents, preparation steps, and preparation parameters. The experimental methods in the following examples are all conventional methods unless otherwise specified; the test materials used in the following examples are all obtained from commercial channels unless otherwise specified.
[0027] Unless otherwise stated, all reagents are used as they are without further purification.
[0028] In the preparation examples and implementation examples of the present invention, unless otherwise specified, "parts" are parts by mass, and unless otherwise specified, concentration percentages are mass concentrations.
[0029] Example 1
[0030] This example provides a method for efficiently synthesizing high-energy cage-shaped CL-20 compounds based on a supported palladium hydroxide catalyst, which includes the following specific steps:
[0031] The core of this technical solution lies in the large-scale preparation of a palladium hydroxide catalyst supported on ultrathin TiO2(B) nanosheets using the impregnation deposition method. The metastable atomic-thick TiO2(B) ultrathin nanosheets, due to the coupling of inherent open channels and the preferential exposure of the (010) plane, this unique open structure can effectively enhance the activity of the material and easily dope other metal or non-metal ions because they rapidly incorporate and diffuse along the exposed channels. A palladium hydroxide catalyst supported on TiO2(B) was prepared on a large scale by the impregnation deposition method. This catalyst has an extremely high dispersion of palladium species. Further, due to the high-activity catalytic interface and high atomic utilization rate of the catalyst, cage-shaped CL-20 was successfully and efficiently prepared. The yield of catalytic hydrogenation debenzylation acetylation product reached 93%, and the Pd usage decreased by 50%.
[0032] A method for efficiently synthesizing high-energy cage-shaped CL-20 compounds based on a supported palladium hydroxide catalyst, which uses a palladium hydroxide catalyst supported on TiO2(B) for catalytic hydrogenation debenzylation.
[0033] Among them, the palladium dosage is 0.1%-1.0% of the mass of the substrate HBIW, the hydrogenation reaction yield is 93%, and the purity of CL-20 is greater than 99.5%;
[0034] These results indicate that the palladium hydroxide catalyst supported on TiO2(B), as a hydrogenation reaction catalyst in the preparation process of CL-20, can greatly reduce production costs, improve synthesis efficiency, and is conducive to large-scale production applications.
[0035] To more clearly illustrate the palladium hydroxide catalyst supported on TiO2(B), its preparation method is now disclosed, and this method includes the following steps:
[0036] Step 1: Mix TiCl4 (1 mL, 0.05 mmol) and 30 mL of ethylene glycol together, and then react at room temperature until no HCl gas is produced.
[0037] Step 2: Then add 1 mL of water to the mixture. Transfer the resulting homogeneous pale yellow solution to a 20 mL high-temperature and high-pressure reactor. Seal the container and heat it at 150 °C for 4 hours, and then cool it to room temperature. The white product is collected by centrifugation, washed with water and ethanol, and then dried in a vacuum oven to obtain ultrathin TiO2(B) nanosheets;
[0038] Step 3: Dissolve 0.84 g of PdCl2 in concentrated hydrochloric acid, add an appropriate amount of deionized water, and then add 5 g of ultrathin TiO2(B) nanosheets. Neutralize with 5% (mass fraction) NaOH solution to pH 10. Filter and wash with water, and then dry in a vacuum oven to obtain a Pd(OH)2 catalyst supported on TiO2(B);
[0039] In this experimental process, Pd is 2+ converted to Pd(OH)2 and deposited on the ultrathin TiO2(B) nanosheets to form a Pd(OH)2 catalyst with a specific Pd loading amount.
[0040] Example 2
[0041] Based on Example 1, this example uses a catalyst for the debenzylation of HBIW, specifically as follows:
[0042] In this example, a high-temperature and high-pressure reactor of the CLF-50ml specification model is used as the hydrogenation reactor; a hydrogen generator is used as the hydrogen source; the high-pressure reactor is subjected to high-speed stirring at 1400 rpm and constant-temperature heating through an intelligent magnetic heating stirrer of the JRCL-DT model.
[0043] Add 1400 mg of HBIW, 50 mL of DMF, 2 mL of bromobenzene, 200 mg of Pd(OH)2 / TiO2 catalyst (3% loading), and 50 μL of acetic anhydride into the reactor. After replacing the air with nitrogen, seal the reaction system and continuously introduce hydrogen. React at room temperature for 2 h and then raise the temperature to 50 °C and react for 8 h. Filter the product, wash it with ethanol and acetone, and dry it. Filter out the catalyst with a sintered glass suction filtration device and then distill the filtrate under reduced pressure to obtain the white solid tetraacetyl dibenzyl hexaazaisowurtzitane (TADBIW). Place 1400 mg of TADBIW in a mixed solution composed of methanol and formic acid to form a slurry. Add 200 mg of Pd(OH)2 / TiO2 catalyst (3% loading) to this slurry under stirring and heat it to 40 - 50 °C and react for 18 h. Filter out the reaction product with the catalyst and extract it with dimethyl sulfoxide to remove the catalyst. Concentrate the extractive solution to precipitate TAIW. Furthermore, purified TAIW can be used for nitrolysis to prepare HNIW (CL-20).
[0044] Example 3
[0045] Step 1: Mix TiCl4 (1 mL, 0.05 mmol) with 30 mL of ethylene glycol, and then carry out the reaction at room temperature until no HCl gas is produced.
[0046] Step 2: Then add 1 mL of water to the mixture. Transfer the resulting homogeneous pale yellow solution to a 20 mL high-temperature and high-pressure autoclave. Seal the container and heat it at 150 °C for 4 hours, and then cool it to room temperature. The white product is collected by centrifugation, washed with water and ethanol, and then dried in a vacuum oven to obtain ultrathin TiO2(B) nanosheets;
[0047] Step 3: Dissolve 0.84 g of PdCl2 in concentrated hydrochloric acid, add an appropriate amount of deionized water, and then add 5 g of ultrathin TiO2(B) nanosheets. Neutralize to pH 12 with 5% (mass fraction) NaOH solution. Filter and wash with water, and then dry in a vacuum oven to obtain a Pd(OH)2 catalyst supported on TiO2(B);
[0048] In this experimental process, Pd is 2+ converted to Pd(OH)2 and deposited on the ultrathin TiO2(B) nanosheets to form a Pd(OH)2 catalyst with a specific Pd loading.
[0049] Example 4
[0050] Step 1: Mix TiCl4 (1 mL, 0.05 mmol) with 30 mL of ethylene glycol, and then carry out the reaction at room temperature until no HCl gas is produced.
[0051] Step 2: Then add 1 mL of water to the mixture. Transfer the resulting homogeneous pale yellow solution to a 20 mL high-temperature and high-pressure autoclave. Seal the container and heat it at 150 °C for 4 hours, and then cool it to room temperature. The white product is collected by centrifugation, washed with water and ethanol, and then dried in a vacuum oven to obtain ultrathin TiO2(B) nanosheets;
[0052] Step 3: Dissolve 0.84 g of PdCl2 in concentrated hydrochloric acid, add an appropriate amount of deionized water, and then add 5 g of ultrathin TiO2(B) nanosheets. Neutralize to pH 14 with 5% (mass fraction) NaOH solution. Filter and wash with water, and then dry in a vacuum oven to obtain a Pd(OH)2 catalyst supported on TiO2(B);
[0053] In this experimental process, Pd is 2+ converted to Pd(OH)2 and deposited on the ultrathin TiO2(B) nanosheets to form a Pd(OH)2 catalyst with a specific Pd loading.
[0054] Performance Test
[0055] The following tests were conducted on the examples:
[0056] Test 1, Purity test of TiO2(B): The purity of ultrathin TiO2(B) nanosheets was tested using an X-ray powder diffractometer of D8 ADVANCE specification at a scanning speed of 6° / min;
[0057] Test 2, Purity test of Pd(OH)2 / TiO2(B) catalyst: The purity of the supported Pd(OH)2 / TiO2(B) catalyst was tested using an X-ray powder diffractometer of D8 ADVANCE model at a scanning speed of 6° / min;
[0058] Test 3, Pd species dispersion degree test of Pd(OH)2 / TiO2(B) catalyst: The Pd species dispersion degree of the supported Pd(OH)2 / TiO2(B) catalyst was tested using a high-throughput transmission electron microscope of JEOL 2800 model;
[0059] Test 4, Nuclear magnetic resonance test of TADBIW intermediate;
[0060] Test 5, High-resolution mass spectrometry test of CL-20;
[0061] Test 4, Scanning electron microscope test of CL-20.
[0062] Please refer to Figure 1 a- Figure 1 as shown in c, Figure 1 a is the X-ray powder diffraction pattern of TiO2(B), Figure 1 b is the X-ray powder diffraction pattern of the supported Pd(OH)2 / TiO2(B) catalyst; The test shows that the purity of the ultrathin TiO2(B) nanosheets and the supported Pd(OH)2 / TiO2(B) catalyst both reached over 99.5%; Figure 1 c and Figure 1 d are the high-throughput transmission electron microscope patterns of the supported Pd(OH)2 / TiO2(B) catalyst. The test shows that the Pd species dispersion degree of the Pd(OH)2 / TiO2(B) catalyst is extremely high, indicating its strong catalytic activity.
[0063] Please refer to Figure 2 as shown, Figure 2 is the 1H nuclear magnetic resonance spectrum of the TADBIW intermediate; The test results show that the purity of the prepared TADBIW intermediate is extremely high, higher than 99.5%.
[0064] Please refer to Figure 3 as shown, Figure 3High-resolution mass spectrometry results of the CL-20 final product prepared by this method. The test results show that the purity of CL-20 is extremely high, higher than 99.5%.
[0065] Please refer to Figure 4 as shown Figure 4 Scanning electron microscope images of the CL-20 final product prepared by this method; the test results show that the purity of CL-20 is extremely high, higher than 99.5%.
[0066] In summary, the present invention proposes a method for efficiently synthesizing the high-energy cage compound CL-20 based on a supported palladium hydroxide catalyst. Through a simple, environmentally friendly and economical one-pot method, high-quality metastable atomically thin TiO2(B) ultrathin nanosheets can be produced on a large scale. Due to the coupling of inherent open channels and the preferential exposure of the (010) plane, this unique open structure can effectively enhance the activity of the material and easily dope other metal or non-metal ions because they rapidly incorporate and diffuse along the exposed channels.
[0067] Furthermore, a Pd(OH)2 catalyst supported on TiO2(B) was macroscopically prepared by the impregnation deposition method. Further, due to the high-activity catalytic interface and high atomic utilization rate of the catalyst, the cage-shaped CL-20 was successfully and efficiently prepared. The yield of the catalytic hydrogenation debenzylation acetylation product reached 93%, and the Pd usage decreased by 50%. This can greatly reduce the production cost, improve the synthesis efficiency, and is conducive to large-scale production applications.
[0068] The present invention not only provides new ideas for the optimized design of supported Pd(OH)2 catalysts, but also solves the bottleneck that the large-scale synthesis of HNIW requires catalysts with high prices. With extremely excellent performance, CL-20 is the best single-component energetic material with comprehensive performance that has been successfully developed and can be used in industrial production so far. In the future, it is expected to be applied on a large scale in aspects such as the propellant of new-generation heavy weapon shells and solid rocket propellants.
[0069] The specific embodiments of the present invention have been described in detail above, but they are only examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions to the present invention are also within the scope of the present invention. Therefore, all equivalent transformations and modifications made without departing from the spirit and scope of the present invention should be covered within the scope of the present invention.
Claims
1. A method for efficiently synthesizing CL-20 high-energy cage compounds based on a supported palladium hydroxide catalyst, characterized in that, It includes the following steps: Using TiO2(B) nanosheets as a carrier, palladium hydroxide is loaded to form a catalyst. Through two-step catalytic hydrogenation debenzylation, hexabenzylhexaazaisowurtzitane is successively converted into tetraacetyl dibenzylhexaazaisowurtzitane and tetraacetylhexaazaisowurtzitane intermediates, and then TAIW is converted into CL-20 through a nitration reaction.
2. The method according to claim 1, wherein The preparation method of the catalyst includes the following steps: a) Mix a titanium source with an alcohol solvent for reaction to generate a TiO2(B) precursor; b) Treat the precursor by hydrothermal method at 100-200 °C to form ultrathin TiO2(B) nanosheets; c) Mix a palladium salt solution with the TiO2(B) nanosheets, adjust the pH to alkaline conditions so that palladium is deposited on the surface of the nanosheets in the form of palladium hydroxide to obtain a supported palladium hydroxide catalyst.
3. The method according to claim 1, wherein The TiO2(B) nanosheets have an open channel structure.
4. The method according to claim 3, wherein The 010 crystal plane of the TiO2(B) nanosheets is preferentially exposed.
5. The method according to claim 1, wherein The palladium atom dispersion of the catalyst is atomic level and the loading amount ≤ 5 wt%.
6. The method according to claim 1, characterized in that, The dispersion of the palladium hydroxide is atomic level, and high-exposure active sites of palladium atoms are realized through the open channel structure of the carrier. The palladium loading amount is 0.1%-5 wt%.
7. The method according to claim 1, characterized in that, In the preparation of the catalyst, the titanium source is TiCl4 or titanate, and the alcohol solvent is ethylene glycol, propylene glycol or glycerol; after the hydrogenation reaction, the intermediates tetraacetyl dibenzylhexaazaisowurtzitane and tetraacetylhexaazaisowurtzitane are purified by organic solvent extraction. The organic solvent is dimethyl sulfoxide, N,N-dimethylformamide or acetone.
8. The method according to claim 1, wherein In the catalytic hydrogenation debenzylation, the amount of palladium used is 0.1%-1.0% of the mass of the substrate HBIW, the reaction temperature is 20-80 °C, and the reaction time is 8-24 hours; the hydrogenation reaction is carried out in two stages: the first stage reacts at room temperature for 2-4 hours, and the second stage is heated to 40-60 °C and reacts for 6-20 hours.
9. The method according to claim 2, wherein In step b), the hydrothermal reaction temperature is 120-180 °C, the reaction time is 2-6 hours, and the thickness of the generated TiO2(B) nanosheets ≤ 5 nm, and the lateral size is 50-200 nm.
10. The method according to claim 2, wherein In step c), the palladium salt is PdCl2, Pd(NO3)2 or Pd(OAc)2, the pH is adjusted to 10-14, and Pd is converted into Pd(OH)2 deposition through alkaline conditions. 2+