Nitrogen-doped titanium dioxide loaded Pd (OH) 2 catalyst as well as preparation method and application thereof

Abstract

The invention discloses a nitrogen-doped titanium dioxide loaded Pd (OH) 2 catalyst as well as a preparation method and application thereof. The preparation method of the catalyst comprises the following steps: (1) preparing the nitrogen-doped titanium dioxide carrier; (2) dissolving PdCl2 in hydrochloric acid to obtain a solution A; (3) adding the nitrogen-doped titanium dioxide carrier and deionized water into a container, and stirring for 10-20 minutes at the temperature of 50-70 DEG C to uniformly mix the nitrogen-doped titanium dioxide carrier and the deionized water; slowly dropwise adding the solution A into a container containing the mixture, and continuously stirring for 5-7 hours; then adjusting the pH to gt by using an alkaline solution; 10, continuously stirring for 1-3 hours, stopping heating, and continuously stirring for 1-3 hours; and finally, carrying out suction filtration and drying to obtain the nitrogen-doped titanium dioxide loaded Pd (OH) 2 catalyst. The invention discloses application of the catalyst in preparation of TAIW through two-step hydrogenolysis debenzylation of HBIW, and the catalyst shows good product yield and stability in two-step reaction.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst preparation, and specifically relates to a nitrogen-doped titanium dioxide-supported Pd(OH)2 catalyst and a preparation method thereof, and application thereof in two-step hydrogenolysis of hexabenzylhexaazaisowurtzitane (HBIW). Background Art

[0002] Improving the energy density of explosives and propellants is an important research direction in both military and civilian fields. Energy density refers to the energy stored per unit volume or unit mass, which is crucial for explosive performance and propulsion effect. Early explosives and propellants used traditional nitrates and organic explosives, which had relatively low energy density, limiting the performance of explosion and propulsion systems. Materials with broad application prospects in rocket, propellant and explosive chemistry are usually high energy density materials (HEDMs).

[0003] In the field of energetic materials, the main focus is currently on the development of advanced solid propellants with higher energy (Is) and environmentally friendly combustion products that are insensitive to explosion. CL-20 is the highest energy compound known in organic chemicals and also the highest density compound. It was first successfully synthesized by Neilsen in 1986. The hydrogenolysis debenzylation of HBIW is considered to be a key step in the synthesis of CL-20. Because of the competitive nitration of the benzene ring, the direct nitration of HBIW to CL-20 by nitration is not successful, so it is necessary to debenzylate HBIW by catalytic hydrogenolysis before nitration. The hydrogenolysis debenzylation reaction of HBIW involves multiple steps, and the use of a large amount of catalysts results in high costs. In addition, due to the easy deactivation of the catalyst and the many side reactions during the reaction, the catalyst recycling rate is low and the yield is low.

[0004] The present invention prepares a nitrogen-doped titanium dioxide-supported Pd(OH)2 catalyst, which has high reaction activity, high selectivity and stability for products, and produces very few by-products during the reaction process, thereby greatly improving the rate and yield of HBIW hydrogenolysis debenzylation. Summary of the invention

[0005] To solve the above problems, the present invention discloses a nitrogen-doped titanium dioxide-supported Pd(OH)2 catalyst, a preparation method thereof, and an application thereof in the two-step hydrogenolysis debenzylation of hexabenzylhexaazaisowurtzitane (HBIW).

[0006] In order to achieve the above-mentioned invention object, the present invention adopts the following technical scheme:

[0007] In a first aspect, the present invention provides a method for preparing a nitrogen-doped titanium dioxide-supported Pd(OH)2 catalyst, comprising the following specific steps:

[0008] (1) Preparation of nitrogen-doped titanium dioxide carrier: titanium-containing organic matter and anhydrous ethanol are mixed, and then a certain amount of nitrogen-containing organic matter is added, and the mixture is stirred for 22-24 hours, centrifuged, and dried in a 100-120° C. forced air oven for 6-8 hours; then, the mixture is ground to obtain a powder; finally, the powder is placed in a muffle furnace and calcined at 300-500° C. for 1-4 hours, and cooled to room temperature to obtain a nitrogen-doped titanium dioxide carrier, which is recorded as TiO2-mN-xy, wherein x represents the calcination temperature, y represents the calcination time, and m represents the molar percentage of the doped nitrogen element to the titanium element, m=1%-5%, and m is calculated based on the feed ratio; the nitrogen-containing organic matter is at least one of pyrrole, pyridine, 1,3,5-tris(4-aminophenyl)benzene, melamine, and L-glutamine;

[0009] (2) dissolving PdCl2 in hydrochloric acid to obtain solution A;

[0010] (3) Add the nitrogen-doped titanium dioxide carrier and deionized water obtained in step (1) into a container, and stir in a water bath at 60-70°C for 10-20 minutes to mix them evenly; slowly drop solution A obtained in step (2) into the container containing the mixture, and continue stirring for 5-7 hours; then use an alkaline solution to adjust the pH to >10 (preferably 11-13, more preferably 11), continue stirring for 1-3 hours, turn off the heating and continue stirring for 1-3 hours; finally, filter and vacuum dry the obtained sample to obtain a nitrogen-doped titanium dioxide-loaded Pd(OH)2 catalyst, so that the Pd loading = the mass of Pd / (the mass of Pd + the mass of the nitrogen-doped titanium dioxide carrier) × 100% = 5wt%-10wt%, wherein the mass of Pd refers to the mass of the Pd element contained in the added solution A.

[0011] Furthermore, in step (1), the titanium-containing organic matter is at least one of tetraethyl titanate, tetraisopropyl titanate, and tetrabutyl titanate.

[0012] Furthermore, in step (1), the volume ratio of the titanium-containing organic matter to anhydrous ethanol is 1:10-30.

[0013] Furthermore, in step (1), the nitrogen-containing organic matter is 1,3,5-tris(4-aminophenyl)benzene, m=5%, the calcination temperature is 350° C., and the calcination time is 2 h.

[0014] Furthermore, in step (1), the dispersant is first dissolved in anhydrous ethanol, and then the titanium-containing organic matter is added, the dispersant is selected from one of triethoxysilane, silyl ether, polyethylene glycol, sodium dodecylbenzene sulfonate, and hexadecyltrimethylammonium bromide, and the mass volume ratio of the dispersant to the titanium-containing organic matter is (1-3) g:10 mL, preferably 2 g:10 mL. Furthermore, the dispersant is selected from sodium dodecylbenzene sulfonate or hexadecyltrimethylammonium bromide, the nitrogen-containing organic matter is 1,3,5-tris(4-aminophenyl)benzene, m=5%, the calcination temperature is 400°C, and the calcination time is 2 hours.

[0015] Furthermore, in step (3), the alkaline solution is an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution or aqueous ammonia.

[0016] Furthermore, in step (3), the vacuum drying temperature is 80-110° C., and the vacuum drying time is 6-12 h.

[0017] In a second aspect, the present invention provides a nitrogen-doped titanium dioxide-loaded Pd(OH)2 catalyst prepared according to the preparation method described in the first aspect.

[0018] In a third aspect, the present invention provides the use of the nitrogen-doped titanium dioxide-supported Pd(OH)2 catalyst in the preparation of tetraacetylhexaazaisowurtzitane (TAIW) by two-step hydrogenolysis debenzylation of hexabenzylhexaazaisowurtzitane (HBIW).

[0019] The preparation of TAIW by two-step hydrogenolysis of hexabenzylhexaazaisowurtzitane (HBIW) is specifically carried out according to the following steps:

[0020] The first step of debenzylation: add hexabenzylhexaazaisowurtzitane, N,N-dimethylformamide, bromobenzene or p-bromotoluene, nitrogen-doped titanium dioxide-supported Pd(OH)2 catalyst, and acetic anhydride into a reaction kettle in sequence, replace the air in the reaction kettle with hydrogen, introduce hydrogen, and react for 20-24 hours under the reaction conditions of 0.4-0.5MPa and 25-40°C. After the hydrogenolysis reaction of HBIW is completed, the hydrogen in the reaction kettle is discharged and filtered, and the filter cake is rinsed with ethanol and dried in a blast oven at 100-110°C for 2-3 hours to obtain a gray solid containing the target product tetraacetyldibenzylhexaazaisowurtzitane (TADBIW) and the catalyst;

[0021] The second step is debenzylation: the gray solid obtained in the first step of debenzylation, acetic acid, nitrogen-doped titanium dioxide-loaded Pd(OH)2 catalyst and water are added to the reactor in sequence, the air in the reactor is replaced by hydrogen, hydrogen is introduced, and the reaction is carried out under the reaction conditions of 1.4-1.5MPa and 40-60°C for 20-24h. The product obtained after hydrogenolysis of TADBIW is tetraacetylhexaazaisowurtzitane (TAIW), which is dissolved in the reaction solvent. After filtering the catalyst, the filtrate is distilled or rectified to obtain tetraacetylhexaazaisowurtzitane (TAIW).

[0022] Furthermore, the feed ratio of hexabenzylhexaazaisowurtzitane, N,N-dimethylformamide, bromobenzene or p-bromotoluene, the nitrogen-doped titanium dioxide-loaded Pd(OH)2 catalyst added in the first step, acetic anhydride, acetic acid, the nitrogen-doped titanium dioxide-loaded Pd(OH)2 catalyst added in the second step, and water is 15g:127mL:0.3mL:0.2g:21mL:127mL:0.2g:18mL.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1) The nitrogen-doped titanium dioxide-loaded Pd(OH)2 catalyst prepared in the present invention introduces defect sites and nitrogen species during the nitrogen doping process in the preparation of the nitrogen-doped titanium dioxide carrier, which is conducive to better dispersion of metallic palladium. Therefore, the nitrogen-doped titanium dioxide-loaded Pd(OH)2 catalyst has good stability in the reaction and can be applied repeatedly.

[0025] 2) The nitrogen-doped titanium dioxide-loaded Pd(OH)2 catalyst prepared in the present invention has excellent acid resistance and a mesoporous structure. The mesoporous structure can reduce the particle size of Pd, thereby increasing the specific surface area of ​​the catalyst and improving the reaction activity. On the other hand, TiO2 and Pd have a strong interaction, and nitrogen doping enhances this effect.

[0026] 3) The nitrogen-doped titanium dioxide-loaded Pd(OH)2 catalyst prepared in the present invention has a surfactant added, which not only increases the electron density of Pd but also improves the dispersibility of PdNPs, and exhibits excellent catalytic performance in hydrogenation reactions.

[0027] 4) The nitrogen-doped titanium dioxide-supported Pd(OH)2 catalyst prepared in the present invention is applied to hexabenzylhexaazaisowurtzitane (HBIW) to prepare tetraacetylhexaazaisowurtzitane (TAIW) via two-step hydrogenolysis debenzylation. The yield of the two-step debenzylation reaction is high and the catalyst stability is good.

[0028] 5) In the method for preparing TADBIW by hydrogenolysis and debenzylation of HBIW according to the present invention, the bromobenzene auxiliary is replaced with p-bromotoluene, which can further improve the yield of TADBIW. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is the XRD diagram of the catalysts prepared in Example 1, Example 10 and Example 11. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is described in more detail below in conjunction with the embodiments. The protection scope of the present invention is not limited to the following specific embodiments.

[0031] If no specific conditions are specified in the examples of the present invention, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be obtained by conventional technical means or purchased commercially.

[0032] Example 1

[0033] (1) 20 mL of tetrabutyl titanate was added to 300 mL of anhydrous ethanol and stirred evenly, then 0.2020 mL of pyrrole was slowly added dropwise, stirred for 24 h, centrifuged, and dried in a 110°C forced air oven for 6 h. After that, the mixture was ground with an agate mortar to obtain a light yellow powder; finally, the light yellow powder was calcined in a muffle furnace at a heating rate of 5°C / min, calcined at 400°C for 2 h, and cooled to room temperature to obtain a nitrogen-doped titanium dioxide carrier, which was recorded as TiO2-5% N-400-2.

[0034] (2) 8.34 g of PdCl2 was placed in 70 mL of concentrated hydrochloric acid and stirred in a 50°C water bath to dissolve. The completely dissolved solution was then transferred to a 100 mL volumetric flask and deionized water was added dropwise to the constant volume mark. Finally, the solution was ultrasonicated for 5 min and shaken to obtain Solution A.

[0035] (3) Weigh 1.8g of the carrier using a weighing balance and place it in a 150mL beaker, add 70mL of deionized water, and stir in a 70°C water bath for 10 minutes to mix evenly. Take 4mL of solution A obtained in step (2) and slowly add it dropwise to the beaker containing deionized water and the carrier. Continue stirring for 5 hours after the addition is complete. Then use sodium hydroxide solution to adjust the pH to 11, continue stirring for 1 hour, turn off the heating and continue stirring for 1 hour. Finally, filter and dry in a vacuum drying oven at 110°C for 8 hours to obtain a nitrogen-doped titanium dioxide-loaded Pd(OH)2 catalyst, in which the Pd loading is 10wt%.

[0036] Example 2

[0037] (1) 20 mL of tetrabutyl titanate was added to 300 mL of anhydrous ethanol and stirred evenly, then 0.2350 mL of pyridine was slowly added dropwise, stirred for 24 h, centrifuged, and dried in a 110°C forced air oven for 6 h. Finally, the mixture was calcined in a muffle furnace at a heating rate of 4°C / min, and then ground with an agate mortar to obtain a light yellow powder; finally, the light yellow powder was calcined in a muffle furnace at 300°C for 2 h, and cooled to room temperature to obtain a nitrogen-doped titanium dioxide carrier, which was recorded as TiO2-5% N-300-2.

[0038] (2) 8.34 g of PdCl2 was placed in 70 mL of concentrated hydrochloric acid and stirred in a 65°C water bath to dissolve. The completely dissolved solution was then transferred to a 100 mL volumetric flask and deionized water was added dropwise to the constant volume mark. Finally, the solution was ultrasonicated for 8 min and shaken to obtain Solution A.

[0039] (3) Weigh 1.9 g of the carrier using a weighing balance and place it in a 150 mL beaker, add 80 mL of deionized water, and stir in a 70 ° C water bath for 13 minutes to mix evenly. Take 2 mL of solution A obtained in step (2) and slowly add it dropwise to the beaker containing deionized water and the carrier. Continue stirring for 5 hours after the addition is complete. Then use sodium hydroxide solution to adjust the pH to 12, continue stirring for 2 hours, turn off the heating and continue stirring for 2 hours. Finally, filter and dry at 100 ° C for 10 hours to obtain a nitrogen-doped titanium dioxide-loaded Pd(OH)2 catalyst, in which the Pd loading is 5wt%.

[0040] Example 3

[0041] (1) 20 mL of tetrabutyl titanate was added to 300 mL of anhydrous ethanol and stirred evenly, then 0.3640 g of 1,3,5-tris(4-aminophenyl)benzene was slowly added, stirred for 24 h, centrifuged, and dried in a 120°C forced air oven for 6 h. Finally, the mixture was calcined in a muffle furnace at a heating rate of 3°C / min, and then ground with an agate mortar to obtain a light yellow powder; finally, the light yellow powder was calcined in a muffle furnace at 350°C for 2 h, and cooled to room temperature to obtain a nitrogen-doped titanium dioxide carrier, which was recorded as TiO2-5%N-350-2.

[0042] (2) 8.34 g of PdCl2 was placed in 70 mL of concentrated hydrochloric acid and stirred in a 60°C water bath to dissolve. The completely dissolved solution was then transferred to a 100 mL volumetric flask and deionized water was added dropwise to the constant volume mark. Finally, the solution was ultrasonicated for 7 min and shaken to obtain Solution A.

[0043] (3) Weigh 1.8g of the carrier using a weighing balance and place it in a 150mL beaker, add 75mL of deionized water, and stir in a 70°C water bath for 10min to mix evenly. Take 4mL of solution A obtained in step (2) and slowly add it dropwise to the beaker containing deionized water and the carrier. Continue stirring for 5h after the addition is complete. Then use sodium hydroxide solution to adjust the pH to 11, continue stirring for 1h, turn off the heating and continue stirring for 1h. Finally, filter and dry at 110°C for 8h to obtain a nitrogen-doped titanium dioxide-loaded Pd(OH)2 catalyst, in which the Pd loading is 10wt%.

[0044] Example 4

[0045] (1) 20 mL of tetrabutyl titanate was added to 300 mL of anhydrous ethanol and stirred evenly, then 0.0611 g of melamine was slowly added, stirred for 24 h, centrifuged, and dried in a 110°C forced air oven for 6 h. Finally, the mixture was calcined in a muffle furnace at a heating rate of 5°C / min, and then ground with an agate mortar to obtain a light yellow powder; finally, the light yellow powder was calcined in a muffle furnace at 450°C for 2 h, and cooled to room temperature to obtain a nitrogen-doped titanium dioxide carrier, which was recorded as TiO2-5% N-450-2.

[0046] (2) 8.34 g of PdCl2 was placed in 70 mL of concentrated hydrochloric acid and stirred in a 60°C water bath to dissolve. The completely dissolved solution was then transferred to a 100 mL volumetric flask and deionized water was added dropwise to the constant volume mark. Finally, the solution was ultrasonicated for 6 min and shaken to obtain Solution A.

[0047] (3) Weigh 1.8g of the carrier using a weighing balance and place it in a 150mL beaker, add 60mL of deionized water, and stir in a 65°C water bath for 15min to mix evenly. Take 4mL of solution A obtained in step (2) and slowly add it dropwise to the beaker containing deionized water and the carrier. Continue stirring for 5h after the addition is complete. Then use sodium hydroxide solution to adjust the pH to 13, continue stirring for 1h, turn off the heating and continue stirring for 1h. Finally, filter with suction and dry at 110°C for 7h to obtain a nitrogen-doped titanium dioxide-loaded Pd(OH)2 catalyst, in which the Pd loading is 10wt%.

[0048] Example 5

[0049] (1) 20 mL of tetrabutyl titanate was added to 300 mL of anhydrous ethanol and stirred evenly, then 0.2125 g of L-glutamine was slowly added, stirred for 24 h, centrifuged, and dried in a 110°C forced air oven for 7 h. Finally, the mixture was calcined in a muffle furnace at a heating rate of 5°C / min, and then ground with an agate mortar to obtain a light yellow powder; finally, the light yellow powder was calcined in a muffle furnace at 500°C for 2 h, and cooled to room temperature to obtain a nitrogen-doped titanium dioxide carrier, which was recorded as TiO2-5% N-500-2.

[0050] (2) 8.34 g of PdCl2 was placed in 70 mL of concentrated hydrochloric acid and stirred in a 60°C water bath to dissolve. The completely dissolved solution was then transferred to a 100 mL volumetric flask and deionized water was added dropwise to the constant volume mark. Finally, the solution was ultrasonicated for 10 min and shaken to obtain Solution A.

[0051] (3) Weigh 1.8g of the carrier using a weighing balance and place it in a 150mL beaker, add 70mL of deionized water, and stir in a 60°C water bath for 10 minutes to mix evenly. Take 4mL of solution A obtained in step (2) and slowly add it dropwise to the beaker containing deionized water and the carrier. Continue stirring for 7 hours after the addition is complete. Then use sodium hydroxide solution to adjust the pH to 12, continue stirring for 3 hours, turn off the heating and continue stirring for 1 hour. Finally, filter and dry at 110°C for 10 hours to obtain a nitrogen-doped titanium dioxide-loaded Pd(OH)2 catalyst, in which the Pd loading is 10wt%.

[0052] Example 6

[0053] (1) 20 mL of tetraisobutyl titanate was added to 300 mL of anhydrous ethanol and stirred evenly, then 0.2660 mL of pyrrole was slowly added dropwise, stirred for 24 h, centrifuged, and dried in a 110°C forced air oven for 8 h. Finally, the mixture was calcined in a muffle furnace at a heating rate of 5°C / min, and then ground with an agate mortar to obtain a light yellow powder; finally, the light yellow powder was calcined in a muffle furnace at 400°C for 1 h, and cooled to room temperature to obtain a nitrogen-doped titanium dioxide carrier, which was recorded as TiO2-5%N-400-1.

[0054] (2) 8.34 g of PdCl2 was placed in 70 mL of concentrated hydrochloric acid and stirred in a 65°C water bath to dissolve. The completely dissolved solution was then transferred to a 100 mL volumetric flask and deionized water was added dropwise to the constant volume mark. Finally, the solution was ultrasonicated for 10 min and shaken to obtain Solution A.

[0055] (3) Weigh 1.85g of the carrier using a weighing balance and place it in a 150mL beaker, add 75mL of deionized water, and stir in a 65°C water bath for 15min to mix evenly. Take 3mL of solution A obtained in step (2) and slowly add it dropwise to the beaker containing deionized water and the carrier. Continue stirring for 5h after the addition is complete. Then use sodium hydroxide solution to adjust the pH to 11, continue stirring for 1h, turn off the heating and continue stirring for 1h. Finally, filter and dry at 110°C for 6h to obtain a nitrogen-doped titanium dioxide-loaded Pd(OH)2 catalyst, in which the Pd loading is 10wt%.

[0056] Example 7

[0057] (1) 20 mL of tetrabutyl titanate was added to 300 mL of anhydrous ethanol and stirred evenly, then 0.0470 mL of pyridine was slowly added dropwise, stirred for 24 h, centrifuged, and dried in a 120°C forced air oven for 6 h. Finally, the mixture was calcined in a muffle furnace at a heating rate of 3°C / min, and then ground with an agate mortar to obtain a light yellow powder; finally, the light yellow powder was calcined in a muffle furnace at 400°C for 3 h, and cooled to room temperature to obtain a nitrogen-doped titanium dioxide carrier, which was recorded as TiO2-1%N-400-3.

[0058] (2) 8.34 g of PdCl2 was placed in 70 mL of concentrated hydrochloric acid and stirred in a 60°C water bath to dissolve. The completely dissolved solution was then transferred to a 100 mL volumetric flask and deionized water was added dropwise to the constant volume mark. Finally, the solution was ultrasonicated for 10 min and shaken to obtain Solution A.

[0059] (3) Weigh 1.8g of the carrier using a weighing balance and place it in a 150mL beaker, add 70mL of deionized water, and stir in a 70°C water bath for 15min to mix evenly. Take 4mL of solution A obtained in step (2) and slowly add it dropwise to the beaker containing deionized water and the carrier. Continue stirring for 5h after the addition is complete. Then use sodium hydroxide solution to adjust the pH to 13, continue stirring for 2h, turn off the heating and continue stirring for 3h. Finally, filter and dry at 100°C for 6h to obtain a nitrogen-doped titanium dioxide-loaded Pd(OH)2 catalyst, in which the Pd loading is 10wt%.

[0060] Example 8

[0061] (1) 20 mL of tetrabutyl titanate was added to 300 mL of anhydrous ethanol and stirred evenly, then 0.0728 g of 1,3,5-tris(4-aminophenyl)benzene was slowly added, stirred for 24 h, centrifuged, and dried in a 100°C forced air oven for 8 h. Finally, the mixture was calcined in a muffle furnace at a heating rate of 5°C / min, and then ground with an agate mortar to obtain a light yellow powder; finally, the light yellow powder was calcined in a muffle furnace at 400°C for 4 h, and cooled to room temperature to obtain a nitrogen-doped titanium dioxide carrier, which was recorded as TiO2-1%N-400-4.

[0062] (2) 8.34 g of PdCl2 was placed in 70 mL of concentrated hydrochloric acid and stirred in a 60°C water bath to dissolve. The completely dissolved solution was then transferred to a 100 mL volumetric flask and deionized water was added dropwise to the constant volume mark. Finally, the solution was ultrasonicated for 8 min and shaken to obtain Solution A.

[0063] (3) Weigh 1.8g of the carrier using a weighing balance and place it in a 150mL beaker, add 60mL of deionized water, and stir in a 65°C water bath for 10 minutes to mix evenly. Take 4mL of solution A obtained in step (2) and slowly add it dropwise to the beaker containing deionized water and the carrier. Continue stirring for 6 hours after the addition is complete. Then use sodium hydroxide solution to adjust the pH to 12, continue stirring for 1 hour, turn off the heating and continue stirring for 1 hour. Finally, filter and dry at 110°C for 8 hours to obtain a nitrogen-doped titanium dioxide-loaded Pd(OH)2 catalyst, in which the Pd loading is 10wt%.

[0064] Example 9

[0065] (1) 20 mL of tetrabutyl titanate was added to 300 mL of anhydrous ethanol and stirred evenly, then 0.03666 g of melamine was slowly added, stirred for 24 h, centrifuged, and dried in a 100°C forced air oven for 8 h. Finally, the mixture was calcined in a muffle furnace at a heating rate of 4°C / min, and then ground with an agate mortar to obtain a light yellow powder; finally, the light yellow powder was calcined in a muffle furnace at 450°C for 3 h, and cooled to room temperature to obtain a nitrogen-doped titanium dioxide carrier, which was recorded as TiO2-3% N-450-3.

[0066] (2) 8.34 g of PdCl2 was placed in 70 mL of concentrated hydrochloric acid and stirred in a 60°C water bath to dissolve. The completely dissolved solution was then transferred to a 100 mL volumetric flask and deionized water was added dropwise to the constant volume mark. Finally, the solution was ultrasonicated for 10 min and shaken to obtain Solution A.

[0067] (3) Weigh 1.8g of the carrier using a weighing balance and place it in a 150mL beaker, add 70mL of deionized water, and stir in a 60°C water bath for 15min to mix evenly. Take 4mL of solution A obtained in step (2) and slowly add it dropwise to the beaker containing deionized water and the carrier. Continue stirring for 5h after the addition is complete. Then use sodium hydroxide solution to adjust the pH to 12, continue stirring for 3h, turn off the heating and continue stirring for 2h. Finally, filter with suction and dry at 110°C for 6h to obtain a nitrogen-doped titanium dioxide-loaded Pd(OH)2 catalyst, in which the Pd loading is 10wt%.

[0068] Example 10

[0069] (1) Weigh 2g of sodium dodecylbenzene sulfonate, add it to 150mL of anhydrous ethanol and stir until it is completely dissolved, then add 10mL of tetrabutyl titanate, then slowly add 0.1820g of 1,3,5-tris(4-aminophenyl)benzene, stir for 24h, centrifuge, and dry in a 100℃ forced air oven for 8h. Finally, calcine in a muffle furnace at a heating rate of 5℃ / min, then grind with an agate mortar to obtain a light yellow powder; finally, place the light yellow powder in a muffle furnace and calcine at 400℃ for 2h, cool to room temperature, and obtain a nitrogen-doped titanium dioxide carrier modified with sodium dodecylbenzene sulfonate, which is recorded as TiO2-5%N-SDBS-400-2.

[0070] (2) 8.34 g of PdCl2 was placed in 70 mL of concentrated hydrochloric acid and stirred in a 60°C water bath to dissolve. The completely dissolved solution was then transferred to a 100 mL volumetric flask and deionized water was added dropwise to the constant volume mark. Finally, the solution was ultrasonicated for 10 min and shaken to obtain Solution A.

[0071] (3) Weigh 1.8g of the carrier using a weighing balance and place it in a 150mL beaker, add 70mL of deionized water, and stir in a 60°C water bath for 15min to mix evenly. Take 4mL of solution A obtained in step (2) and slowly add it dropwise to the beaker containing deionized water and the carrier. Continue stirring for 5h after the addition is complete. Then use sodium hydroxide solution to adjust the pH to 12, continue stirring for 1h, turn off the heating and continue stirring for 1h. Finally, filter with suction and dry at 110°C for 6h to obtain a nitrogen-doped titanium dioxide-loaded Pd(OH)2 catalyst modified with sodium dodecylbenzenesulfonate, in which the Pd loading is 10wt%.

[0072] Embodiment 11

[0073] (1) Weigh 2 g of hexadecyltrimethylammonium bromide, add it to 150 mL of anhydrous ethanol and stir until it is completely dissolved, then add 10 mL of tetrabutyl titanate, then slowly add 0.1820 g of 1,3,5-tris(4-aminophenyl)benzene, stir for 24 h, centrifuge, and dry in a 100 °C forced air oven for 8 h. Finally, calcine in a muffle furnace at a heating rate of 5 °C / min, then grind with an agate mortar to obtain a light yellow powder; finally, place the light yellow powder in a muffle furnace and calcine at 400 °C for 2 h, cool to room temperature, and obtain a nitrogen-doped titanium dioxide carrier modified with sodium dodecylbenzene sulfonate, which is recorded as.

[0074] (2) 8.34 g of PdCl2 was placed in 70 mL of concentrated hydrochloric acid and stirred in a 60°C water bath to dissolve. The completely dissolved solution was then transferred to a 100 mL volumetric flask and deionized water was added dropwise to the constant volume mark. Finally, the solution was ultrasonicated for 10 min and shaken to obtain Solution A.

[0075] (3) Weigh 1.8g of the carrier using a weighing balance and place it in a 150mL beaker, add 70mL of deionized water, and stir in a 60°C water bath for 15min to mix evenly. Take 4mL of solution A obtained in step (2) and slowly add it dropwise to the beaker containing deionized water and the carrier. Continue stirring for 5h after the addition is complete. Then use sodium hydroxide solution to adjust the pH to 13, continue stirring for 1h, turn off the heating and continue stirring for 1h. Finally, filter with suction and dry at 110°C for 6h to obtain a nitrogen-doped titanium dioxide-loaded Pd(OH)2 catalyst modified with sodium dodecylbenzenesulfonate, in which the Pd loading is 10wt%.

[0076] Example 12

[0077] The application of different nitrogen-doped titanium dioxide-supported Pd(OH)2 catalysts prepared in Examples 1 to 9 in the two-step hydrogenolysis of hexabenzylhexaazaisowurtzitane (HBIW) was investigated.

[0078] In the first step of debenzylation, hexabenzyl hexaazaisowurtzitane, N, N-dimethylformamide, bromobenzene, nitrogen-doped titanium dioxide-supported Pd(OH)2 catalyst, and acetic anhydride were added to a 250 mL reactor in sequence, with a feed ratio of 15 g: 127 mL: 0.3 mL: 0.2 g: 21 mL. The air in the reactor was replaced with hydrogen 5 times, and hydrogen was introduced. The reaction was carried out under the reaction conditions of 0.5 MPa and 40 ° C for 24 hours. After the hydrogenolysis reaction of HBIW was completed, the hydrogen in the reactor was discharged and filtered, and the filter cake was rinsed with ethanol three times. Dry it at 110 ° C in a blast oven for 2 hours to obtain a gray solid containing the target product tetraacetyldibenzylhexaazaisowurtzitane (TADBIW) and the catalyst. In the second step of debenzylation, the gray solid in the first step, 127 mL of acetic acid, 0.2 g of nitrogen-doped titanium dioxide-loaded Pd(OH)2 catalyst, and 18 mL of water were added to the reactor in sequence. The air in the reactor was replaced with hydrogen 5 times, and hydrogen was introduced. The reaction was carried out under reaction conditions of 1.5 MPa and 60°C for 24 hours. The product obtained after hydrogenolysis of TADBIW was tetraacetylhexaazaisowurtzitane (TAIW), which was dissolved in the reaction solvent. After filtering the catalyst, the filtrate was analyzed by liquid chromatography. The experimental results are shown in Table 1.

[0079] Table 1 Catalytic hydrogenation debenzylation performance of Pd(OH)2 / TN catalysts prepared by TN carrier calcined at different calcination temperatures and times

[0080] catalyst First step yield (%) Second step yield (%) Example 1 52 91 Example 2 59 92 Example 3 78 92 Example 4 71 87 Example 5 33 93 Example 6 71 61 Example 7 73 70 Example 8 71 72 Example 9 68 82

[0081] Embodiment 13

[0082] The application of nitrogen-doped titanium dioxide-supported Pd(OH)2 catalysts prepared in Examples 3, 10 and 11 in the two-step hydrogenolysis of hexabenzylhexaazaisowurtzitane (HBIW) was investigated. The application process and conditions were the same as in Example 12. The experimental results are shown in Table 2.

[0083] Table 2 Comparison of the hydrogenation performance of catalysts modified by different surfactant supports

[0084] catalyst First step yield (%) Second step yield (%) Example 3 78 92 Example 10 79 93 Embodiment 11 77 95

[0085] Comparative Example 1 (Compared with Example 3)

[0086] Comparative Example 1 investigated the reaction performance of commercial titanium dioxide (P25) supported Pd(OH)2 catalyst.

[0087] 8.34 g PdCl2 was placed in 70 mL concentrated hydrochloric acid, stirred and dissolved in a 60°C water bath, and then the completely dissolved solution was transferred to a 100 mL volumetric flask, and deionized water was added dropwise to the constant volume mark. Finally, ultrasonicated for 10 min and shaken to obtain solution A.

[0088] Weigh 1.8g of commercial TiO2 carrier on a weighing balance and put it into a 150mL beaker, add 70mL of deionized water, and stir in a 70℃ water bath for 10min to mix it evenly. Take 4mL of solution A and slowly add it dropwise to the beaker containing deionized water and the carrier. Continue stirring for 5h after the addition is complete. Then adjust the pH to 11 with sodium hydroxide solution, continue stirring for 1h, and continue stirring for 1h after turning off the heating. Finally, filter and dry at 110℃ for 8h. A titanium dioxide-loaded Pd(OH)2 catalyst is obtained, in which the Pd loading is 10wt%.

[0089] The application of the prepared titanium dioxide supported Pd(OH)2 catalyst in the two-step hydrogenolysis debenzylation of hexabenzylhexaazaisowurtzitane (HBIW) was investigated. The application process and conditions were the same as those in Example 12, and the first step debenzylation yield was 72% and the second step debenzylation yield was 90%.

[0090] Comparative Example 2 (Compared with Example 3)

[0091] Comparative Example 2 investigated the reaction performance of nitrogen and fluorine co-doped titanium dioxide supported Pd(OH)2 catalyst.

[0092] (1) NaF was used as the F source, added to 150 mL of anhydrous ethanol and stirred until completely dissolved, then 10 mL of tetrabutyl titanate was added, and then 0.3640 g of 1,3,5-tris(4-aminophenyl)benzene was slowly added, stirred for 24 h, centrifuged, and repeatedly washed with deionized water. Dry in a 110 °C forced air oven for 6 h. Finally, calcined in a muffle furnace at 400 °C for 2 h, with a heating rate of 5 °C / min. A nitrogen and fluorine co-doped titanium dioxide carrier was obtained. This carrier was recorded as TN-F.

[0093] (2) 8.34 g of PdCl2 was placed in 70 mL of concentrated hydrochloric acid, stirred and dissolved in a water bath at 60 ° C, and then the completely dissolved solution was transferred to a 100 mL volumetric flask, and deionized water was added to the constant volume mark. Finally, ultrasonic for 10 minutes and shaken to obtain solution A. 1.8 g of the carrier was weighed with a weighing balance and placed in a 150 mL beaker, and 70 mL of deionized water was added, and stirred in a water bath at 70 ° C for 10 minutes to mix evenly. 4 mL of solution A was slowly added to the beaker containing deionized water and the carrier, and continued to stir for 5 hours after the addition was completed. Then, the pH was adjusted to 11 with sodium hydroxide solution, and continued to stir for 1 hour. After turning off the heating, continue to stir for 1 hour. Finally, filter and dry at 110 ° C for 8 hours. A nitrogen and fluorine co-doped titanium dioxide supported Pd(OH)2 catalyst was obtained, in which the Pd loading was 10wt%.

[0094] (3) The application of the prepared nitrogen and fluorine co-doped titanium dioxide supported Pd(OH)2 catalyst in the two-step hydrogenolysis debenzylation of hexabenzylhexaazaisowurtzitane (HBIW) was investigated. The application process and conditions were the same as those in Example 12. The first step debenzylation yield was 64% and the second step debenzylation yield was 77%.

[0095] Comparative Example 3 (Compared with Example 3)

[0096] Comparative Example 3 investigated the reaction performance of nitrogen and phosphorus co-doped titanium dioxide supported Pd(OH)2 catalyst.

[0097] (1) Take 2 g of TN-400-2 powder prepared in Example 3 and use the equal volume impregnation method. Orthophosphoric acid and 3 mL of deionized water are mixed evenly and added dropwise to the culture dish containing TN-400-2 powder. After impregnation for 24 hours, dry it in a 100°C forced air oven for 8 hours. Finally, calcine it at 400°C in a muffle furnace for 2 hours with a heating rate of 5°C / min. Recorded as TN-P.

[0098] (2) 8.34 g of PdCl2 was placed in 70 mL of concentrated hydrochloric acid, stirred and dissolved in a water bath at 60 ° C, and then the completely dissolved solution was transferred to a 100 mL volumetric flask, and deionized water was added to the constant volume mark. Finally, ultrasonic for 10 minutes and shaken to obtain solution A. 1.8 g of the carrier was weighed with a weighing balance and placed in a 150 mL beaker, and 70 mL of deionized water was added, and stirred in a water bath at 70 ° C for 10 minutes to mix evenly. 4 mL of solution A was slowly added to the beaker containing deionized water and the carrier, and continued to stir for 5 hours after the addition was completed. Then, the pH was adjusted to 11 with sodium hydroxide solution, and continued to stir for 1 hour. After turning off the heating, continue to stir for 1 hour. Finally, filter and dry at 110 ° C for 8 hours. A nitrogen and phosphorus co-doped titanium dioxide supported Pd(OH)2 catalyst was obtained, in which the Pd loading was 10wt%.

[0099] (3) The application of the prepared nitrogen and phosphorus co-doped titanium dioxide supported Pd(OH)2 catalyst in the two-step hydrogenolysis debenzylation of hexabenzylhexaazaisowurtzitane (HBIW) was investigated. The application process and conditions were the same as those in Example 12, and the first step debenzylation yield was 55% and the second step debenzylation yield was 80%.

[0100] Comparative Example 4 (Compared with Example 3)

[0101] Comparative Example 4 investigated the reaction performance of nitrogen and sulfur co-doped titanium dioxide supported Pd(OH)2 catalyst.

[0102] (1) KSCN was added as the S source to 150 mL of anhydrous ethanol and stirred until completely dissolved. Then 10 mL of tetrabutyl titanate was added, and then 0.3640 g of 1,3,5-tri(4-aminophenyl)benzene was slowly added. The mixture was stirred for 24 h, centrifuged, and repeatedly washed with deionized water. The mixture was dried in a 110 °C forced air oven for 6 h. Finally, the mixture was calcined in a muffle furnace at 400 °C for 2 h with a heating rate of 5 °C / min. A nitrogen and fluorine co-doped titanium dioxide carrier was obtained. This carrier was recorded as TN-S.

[0103] (2) 8.34 g of PdCl2 was placed in 70 mL of concentrated hydrochloric acid, stirred and dissolved in a water bath at 60 ° C, and then the completely dissolved solution was transferred to a 100 mL volumetric flask, and deionized water was added to the constant volume mark. Finally, ultrasonic for 10 minutes and shaken to obtain solution A. 1.8 g of the carrier was weighed with a weighing balance and placed in a 150 mL beaker, and 70 mL of deionized water was added, and stirred in a water bath at 70 ° C for 10 minutes to mix evenly. 4 mL of solution A was slowly added dropwise to the beaker containing deionized water and the carrier, and continued to stir for 5 hours after the addition was completed. Then, the pH was adjusted to 11 with sodium hydroxide solution, and continued to stir for 1 hour. After turning off the heating, continue to stir for 1 hour. Finally, filter and dry at 110 ° C for 8 hours. A nitrogen and sulfur co-doped titanium dioxide supported Pd(OH)2 catalyst was obtained, in which the Pd loading was 10wt%.

[0104] (3) The application of the prepared nitrogen and sulfur co-doped titanium dioxide supported Pd(OH)2 catalyst in the two-step hydrogenolysis debenzylation of hexabenzylhexaazaisowurtzitane (HBIW) was investigated. The application process and conditions were the same as those in Example 12. The first step debenzylation yield was 64% and the second step debenzylation yield was 81%.

[0105] Comparative Example 5 (Compared with Example 3)

[0106] Comparative Example 5 investigated the reaction performance of sulfur-doped titanium dioxide-supported Pd(OH)2 catalyst.

[0107] (1) KSCN was added as the sulfur source to 150 mL of anhydrous ethanol and stirred until completely dissolved. Then 10 mL of tetrabutyl titanate was added, stirred for 24 h, centrifuged, and repeatedly washed with deionized water. Dry in a 110°C forced air oven for 6 h. Finally, calcined in a muffle furnace at 400°C for 2 h with a heating rate of 5°C / min. A sulfur-doped titanium dioxide carrier was obtained. This carrier was denoted as TS.

[0108] (2) 8.34 g of PdCl2 was placed in 70 mL of concentrated hydrochloric acid, stirred and dissolved in a water bath at 60 ° C, and then the completely dissolved solution was transferred to a 100 mL volumetric flask, and deionized water was added to the constant volume mark. Finally, ultrasonic for 10 minutes and shaken to obtain solution A. 1.8 g of the carrier was weighed with a weighing balance and placed in a 150 mL beaker, and 70 mL of deionized water was added, and stirred in a water bath at 70 ° C for 10 minutes to mix evenly. 4 mL of solution A was slowly added to the beaker containing deionized water and the carrier, and continued to stir for 5 hours after the addition was completed. Then, the pH was adjusted to 11 with sodium hydroxide solution, and continued to stir for 1 hour. After turning off the heating, continue to stir for 1 hour. Finally, filter and dry at 110 ° C for 8 hours. A sulfur-doped titanium dioxide-supported Pd(OH)2 catalyst was obtained, in which the Pd loading was 10 wt%.

[0109] (3) The application of the prepared sulfur-doped titanium dioxide-supported Pd(OH)2 catalyst in the two-step hydrogenolysis debenzylation of hexabenzylhexaazaisowurtzitane (HBIW) was investigated. The application process and conditions were the same as those in Example 12, and the first step debenzylation yield was 14% and the second step debenzylation yield was 23%.

[0110] Comparative Example 6 (Compared with Example 3)

[0111] Comparative Example 6 investigated the reaction performance of phosphorus-doped titanium dioxide-supported Pd(OH)2 catalyst.

[0112] (1) Use the equal volume impregnation method. Orthophosphoric acid was mixed with 3 mL of deionized water and added dropwise to a culture dish containing commercial TiO2 powder. After impregnation for 24 h, it was dried in a forced air oven at 80 °C for 8 h. Finally, it was calcined in a muffle furnace at 400 °C for 2 h with a heating rate of 5 °C / min. This was recorded as TP.

[0113] (2) 8.34 g of PdCl2 was placed in 70 mL of concentrated hydrochloric acid, stirred and dissolved in a water bath at 60 ° C, and then the completely dissolved solution was transferred to a 100 mL volumetric flask, and deionized water was added to the constant volume mark. Finally, ultrasonic for 10 minutes and shaken to obtain solution A. 1.8 g of the carrier was weighed with a weighing balance and placed in a 150 mL beaker, and 70 mL of deionized water was added, and stirred in a water bath at 70 ° C for 10 minutes to mix evenly. 4 mL of solution A was slowly added to the beaker containing deionized water and the carrier, and continued to stir for 5 hours after the addition was completed. Then, the pH was adjusted to 11 with sodium hydroxide solution, and continued to stir for 1 hour. After turning off the heating, continue to stir for 1 hour. Finally, filter and dry at 110 ° C for 8 hours. A phosphorus-doped titanium dioxide-supported Pd(OH)2 catalyst was obtained, in which the Pd loading was 10 wt%.

[0114] (3) The application of the prepared phosphorus-doped titanium dioxide-supported Pd(OH)2 catalyst in the two-step hydrogenolysis debenzylation of hexabenzylhexaazaisowurtzitane (HBIW) was investigated. The application process and conditions were the same as those in Example 12. The first step debenzylation yield was 23%, and the second step debenzylation yield was 33%.

[0115] Comparative Example 7

[0116] Comparative Example 7 investigated the effect of solvent on the performance of the catalyst in the HBIW hydrogenolysis debenzylation reaction.

[0117] (1) 20 mL of tetrabutyl titanate was added to 300 mL of anhydrous ethanol and stirred evenly, then 0.3640 g of 1,3,5-tris(4-aminophenyl)benzene was slowly added, stirred for 24 h, centrifuged, and dried in a 120°C forced air oven for 6 h. Finally, the mixture was calcined in a muffle furnace at a heating rate of 3°C / min, and then ground with an agate mortar to obtain a light yellow powder; finally, the light yellow powder was calcined in a muffle furnace at 350°C for 2 h, and cooled to room temperature to obtain a nitrogen-doped titanium dioxide carrier, which was recorded as TN-350-2.

[0118] (2) 8.34 g of PdCl2 was placed in 70 mL of concentrated hydrochloric acid and stirred in a 60°C water bath to dissolve. The completely dissolved solution was then transferred to a 100 mL volumetric flask and deionized water was added dropwise to the constant volume mark. Finally, the solution was ultrasonicated for 10 min and shaken to obtain Solution A.

[0119] (3) Weigh 1.8g of the carrier using a weighing balance and place it in a 150mL beaker, add 75mL of deionized water, and stir in a 65°C water bath for 15min to mix evenly. Take 4mL of solution A obtained in step (2) and slowly add it dropwise to the beaker containing deionized water and the carrier. Continue stirring for 6h after the addition is complete. Then use sodium hydroxide solution to adjust the pH to 11, continue stirring for 1h, turn off the heating and continue stirring for 1h. Finally, filter with suction and dry at 120°C for 8h to obtain a nitrogen-doped titanium dioxide-loaded Pd(OH)2 catalyst, in which the Pd loading is 10wt%.

[0120] (4) The application of the prepared nitrogen-doped titanium dioxide-supported Pd(OH)2 catalyst in the two-step hydrogenolysis debenzylation of hexabenzylhexaazaisowurtzitane (HBIW) was investigated. The application process and conditions were similar to those in Example 12, except that the solvent in the first step of debenzylation was replaced with N,N-dimethylacetamide, resulting in a first step debenzylation yield of 0% and a second step debenzylation yield of 70%.

[0121] Comparative Example 8

[0122] Comparative Example 8 investigated the effect of the additive on the catalyst performance in the HBIW hydrogenolysis debenzylation reaction.

[0123] (1) 20 mL of tetrabutyl titanate was added to 300 mL of anhydrous ethanol and stirred evenly, then 0.3640 g of 1,3,5-tris(4-aminophenyl)benzene was slowly added, stirred for 24 h, centrifuged, and dried in a 120°C forced air oven for 6 h. Finally, the mixture was calcined in a muffle furnace at a heating rate of 3°C / min, and then ground with an agate mortar to obtain a light yellow powder; finally, the light yellow powder was calcined in a muffle furnace at 350°C for 2 h, and cooled to room temperature to obtain a nitrogen-doped titanium dioxide carrier, which was recorded as TN-350-2.

[0124] (2) 8.34 g of PdCl2 was placed in 70 mL of concentrated hydrochloric acid and stirred in a 60°C water bath to dissolve. The completely dissolved solution was then transferred to a 100 mL volumetric flask and deionized water was added dropwise to the constant volume mark. Finally, the solution was ultrasonicated for 10 min and shaken to obtain Solution A.

[0125] (3) Weigh 1.8g of the carrier using a weighing balance and place it in a 150mL beaker, add 75mL of deionized water, and stir in a 65°C water bath for 15min to mix evenly. Take 4mL of solution A obtained in step (2) and slowly add it dropwise to the beaker containing deionized water and the carrier. Continue stirring for 6h after the addition is complete. Then use sodium hydroxide solution to adjust the pH to 11, continue stirring for 1h, turn off the heating and continue stirring for 1h. Finally, filter and dry at 120°C for 8h to obtain a nitrogen-doped titanium dioxide-loaded Pd(OH)2 catalyst, in which the Pd loading is 10wt%.

[0126] (4) The application of the prepared nitrogen-doped titanium dioxide-supported Pd(OH)2 catalyst in the two-step hydrogenolysis debenzylation of hexabenzylhexaazaisowurtzitane (HBIW) was investigated. The application process and conditions were similar to those in Example 12, except that bromobenzene in the first step of debenzylation was replaced by p-bromotoluene, resulting in a first step debenzylation yield of 81% and a second step debenzylation yield of 95%.

Claims

1. A method for preparing a nitrogen-doped titanium dioxide-supported Pd(OH)2 catalyst, characterized in that: The preparation method comprises the following specific steps: (1) Preparation of nitrogen-doped titanium dioxide carrier: titanium-containing organic matter and anhydrous ethanol are mixed, and then a certain amount of nitrogen-containing organic matter is added, and the mixture is stirred for 22-24 hours, centrifuged, and dried in a 100-120° C. forced air oven for 6-8 hours; then, the mixture is ground to obtain a powder; finally, the powder is placed in a muffle furnace and calcined at 300-500° C. for 1-4 hours, and cooled to room temperature to obtain a nitrogen-doped titanium dioxide carrier, which is recorded as TiO2-mN-xy, wherein x represents the calcination temperature, y represents the calcination time, and m represents the molar percentage of the doped nitrogen element to the titanium element, m=1%-5%, and m is calculated based on the feed ratio; the nitrogen-containing organic matter is at least one of pyrrole, pyridine, 1,3,5-tris(4-aminophenyl)benzene, melamine, and L-glutamine; (2) dissolving PdCl2 in hydrochloric acid to obtain solution A; (3) Add the nitrogen-doped titanium dioxide carrier and deionized water obtained in step (1) into a container, and stir in a water bath at 60-70°C for 10-20 minutes to mix them evenly; slowly drop solution A obtained in step (2) into the container containing the mixture, and continue stirring for 5-7 hours; then use an alkaline solution to adjust the pH to >10, continue stirring for 1-3 hours, turn off the heating and continue stirring for 1-3 hours; finally, filter and vacuum dry the obtained sample to obtain a nitrogen-doped titanium dioxide-loaded Pd(OH)2 catalyst, so that the Pd loading = the mass of Pd / (the mass of Pd + the mass of the nitrogen-doped titanium dioxide carrier) × 100% = 5wt%-10wt%, wherein the mass of Pd refers to the mass of the Pd element contained in the added solution A.

2. The preparation method according to claim 1, characterized in that: In step (1), the titanium-containing organic matter is at least one of tetraethyl titanate, tetraisopropyl titanate, and tetrabutyl titanate.

3. The preparation method according to claim 1, characterized in that: In step (1), the volume ratio of the titanium-containing organic matter to anhydrous ethanol is 1:10-30.

4. The preparation method according to claim 1, characterized in that: In step (1), the nitrogen-containing organic matter is 1,3,5-tri(4-aminophenyl)benzene, m=5%, the calcination temperature is 350° C., and the calcination time is 2 h.

5. The preparation method according to claim 1, characterized in that: In step (1), a dispersant is first dissolved in anhydrous ethanol, and then the titanium-containing organic matter is added. The dispersant is selected from one of triethoxysilane, silane ether, polyethylene glycol, sodium dodecylbenzene sulfonate, and hexadecyltrimethylammonium bromide. The mass volume ratio of the dispersant to the titanium-containing organic matter is (1-3) g:10 mL.

6. The preparation method according to claim 5, characterized in that: The dispersant is selected from sodium dodecylbenzenesulfonate or hexadecyltrimethylammonium bromide, the nitrogen-containing organic matter is 1,3,5-tris(4-aminophenyl)benzene, m=5%, the calcination temperature is 400° C., and the calcination time is 2 hours.

7. The preparation method according to claim 1, characterized in that: In step (3), the alkaline solution is a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution or an ammonia solution; the vacuum drying temperature is 80-110° C., and the vacuum drying time is 6-12 h.

8. A nitrogen-doped titanium dioxide-supported Pd(OH)2 catalyst prepared according to the preparation method of any one of claims 1 to 7.

9. Use of the nitrogen-doped titanium dioxide-supported Pd(OH)2 catalyst as claimed in claim 8 in the preparation of tetraacetylhexaazaisowurtzitane by two-step hydrogenolysis of hexabenzylhexaazaisowurtzitane.

10. The use according to claim 9, characterized in that: The preparation of tetraacetylhexaazaisowurtzitane by two-step hydrogenolysis of hexabenzylhexaazaisowurtzitane is specifically carried out according to the following steps: The first step of debenzylation: add hexabenzylhexaazaisowurtzitane, N,N-dimethylformamide, bromobenzene or p-bromotoluene, nitrogen-doped titanium dioxide-supported Pd(OH)2 catalyst, and acetic anhydride into a reaction kettle in sequence, replace the air in the reaction kettle with hydrogen, introduce hydrogen, and react for 20-24 hours under the reaction conditions of 0.4-0.5MPa and 25-40°C. After the HBIW hydrogenolysis reaction is completed, the hydrogen in the reaction kettle is discharged and filtered, and the filter cake is rinsed with ethanol and dried in a blast oven at 100-110°C for 2-3 hours to obtain a gray solid containing the target product tetraacetyldibenzylhexaazaisowurtzitane and the catalyst; The second step is debenzylation: the gray solid obtained in the first step of debenzylation, acetic acid, nitrogen-doped titanium dioxide-loaded Pd(OH)2 catalyst and water are added to the reactor in sequence, the air in the reactor is replaced by hydrogen, hydrogen is introduced, and the reaction is carried out under the reaction conditions of 1.4-1.5MPa and 40-60°C for 20-24h. The product obtained after hydrogenolysis of tetraacetyldibenzylhexaazaisowurtzitane is tetraacetylhexaazaisowurtzitane, which is dissolved in the reaction solvent. After filtering the catalyst, the filtrate is distilled or rectified to obtain tetraacetylhexaazaisowurtzitane.

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