Iron-based MOF and induced titanium dioxide composite catalyst, preparation method and application

Abstract

The present invention provides an iron-based MOF and induced titanium dioxide composite catalyst, a preparation method and an application, including: Step 1, loading TiO2 on the surface of a MOF(Fe) carrier to form a MOF(Fe)@TiO2 composite catalyst. Step 2, loading TiO2 on the surface of a Fe2O3-HT carrier to form a Fe2O3-HT@TiO2 composite catalyst. Step 3, subjecting the MOF(Fe)@TiO2 prepared in Step 2 to high-temperature calcination and annealing under atmosphere protection to obtain a Fe2O3@TiO2-HT composite catalyst. The composite catalyst is used as a catalyst for the thermal decomposition of ammonium perchlorate. The present invention explores the application of MOF(Fe) and Fe2O3 materials in the catalytic thermal decomposition reaction of AP and obtains good catalytic performance. Compared with the traditional TiO2 (P25) catalyst, the high-temperature decomposition peak temperature for catalyzing the thermal decomposition of AP is significantly advanced.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanomaterials, relates to a catalyst for composite solid propellants, and particularly relates to an iron-based MOF and induced titanium dioxide composite catalyst, a preparation method and an application thereof. Background Art

[0002] Composite solid propellants are composed of oxidizers, additives, binders and fuels, and are the power sources widely used in aviation, aerospace and missiles. Among these components, the oxidizer usually occupies more than half of the composite solid propellant, greatly affecting the performance of the composite solid propellant. Ammonium perchlorate (AP) is a common oxidizer in composite solid propellants, and its thermal decomposition performance has an important impact on the combustion performance of composite solid propellants. It is reported that AP-based composite solid propellants can exhibit high specific impulse, low pressure index and fast burning rate by increasing the heat release of AP and reducing the decomposition temperature of AP. Therefore, promoting the thermal decomposition of AP can improve the combustion performance of composite solid propellants. Summary of the Invention

[0003] Aiming at the deficiencies existing in the prior art, the purpose of the present invention is to provide an iron-based MOF and induced titanium dioxide composite catalyst, a preparation method and an application thereof, so as to solve the technical problem that the thermal decomposition temperature of the thermal decomposition catalyst of the composite solid propellant in the prior art needs to be further advanced.

[0004] To solve the above technical problems, the present invention is implemented by adopting the following technical solutions:

[0005] A preparation method of a composite catalyst, wherein the composite catalyst is a MOF(Fe)@TiO2 composite catalyst, a Fe2O3-HT@TiO2 composite catalyst or a Fe2O3@TiO2-HT composite catalyst.

[0006] The preparation method of the MOF(Fe)@TiO2 composite catalyst adopts Step 1.

[0007] The preparation method of the Fe2O3-HT@TiO2 composite catalyst adopts Step 2.

[0008] The preparation method of the Fe2O3@TiO2-HT composite catalyst adopts Step 1 and Step 3.

[0009] Step 1, load TiO2 on the surface of the MOF(Fe) carrier by atomic layer deposition to form a MOF(Fe)@TiO2 composite catalyst.

[0010] Step 2: Under an atmosphere protection, the MOF(Fe) support is annealed by high-temperature calcination to obtain an Fe2O3 support induced by MOF(Fe), namely the Fe2O3-HT support; then, TiO2 is loaded on the surface of the Fe2O3-HT support by atomic layer deposition to form an Fe2O3-HT@TiO2 composite catalyst.

[0011] Step 3: Under an atmosphere protection, the MOF(Fe)@TiO2 prepared in Step 2 is annealed by high-temperature calcination to obtain an Fe2O3@TiO2-HT composite catalyst.

[0012] The present invention also has the following technical features:

[0013] Preferably, in Step 1, the particle size of the MOF(Fe) support is 1 - 2 μm; in Step 2, the particle size of the Fe2O3-HT support is 200 - 600 nm.

[0014] Specifically, in Step 1 and Step 2, the specific process of loading TiO2 by atomic layer deposition is as follows:

[0015] Step1: The support material is laid flat on the sample stage, and this sample stage is placed in the reaction chamber of atomic layer deposition and the outlet is sealed. The air in the reaction chamber is pumped out by a mechanical vacuum pump; the temperature is set and raised. The temperature of the reaction chamber is 150 °C, and the temperature of the titanium source is set at 45 °C.

[0016] Step2: An inert carrier gas with a total flow rate of 50 - 150 ml / min is introduced into the reaction chamber from the inlet of the atomic layer deposition equipment, and pumped out at the outlet by a mechanical pump to keep the vacuum degree in the reaction chamber stable at 10 - 100 Pa; the titanium source is injected into the reaction chamber by bubbling, so that the titanium source molecules are saturated chemically adsorbed on the surface of the support material. After the titanium source is saturatedly adsorbed on the support surface, the injection of the titanium source is stopped, and the physically adsorbed or excess titanium source is blown away from the system by an inert gas flow.

[0017] Step3: Similarly, the oxidant molecules are injected into the reaction chamber by bubbling, so that the oxidant molecules react with the iron source adsorbed on the support surface through redox reaction; after the reaction is completed, the injection of the oxidant molecules is stopped, and the physically adsorbed or excess oxidant molecules and by-products are blown away from the system by an inert gas flow.

[0018] Step4: Step 2 and Step 3 are one cycle of titanium dioxide deposition; by increasing the number of cycles of titanium dioxide deposition, different loadings of titanium dioxide are controlled to prepare composite catalysts with different numbers of titanium dioxide cycles.

[0019] Preferably, the carrier material is MOF(Fe) carrier in Step 1 and Fe2O3-HT carrier in Step 2; the titanium source is titanium tetraisopropoxide; the oxidant is hydrogen peroxide; the inert carrier gas is high-purity nitrogen or high-purity argon.

[0020] Specifically, in Step 1, the MOF(Fe) carrier is prepared by hydrothermal method. The specific process is as follows: Place FeCl3·6H2O in the polytetrafluoroethylene inner liner of a hydrothermal autoclave, add terephthalic acid, then pour DMF into the polytetrafluoroethylene inner liner and start stirring for 30 min; Place this polytetrafluoroethylene inner liner into the stainless-steel outer shell of the hydrothermal autoclave, place it in an oven and keep it at 150 °C for 2 h; After the temperature drops to room temperature, centrifuge to collect the sample, wash it with deionized water, and dry it in an oven at 80 °C to obtain the MOF(Fe) carrier.

[0021] Preferably, in Step 2, the temperature of the high-temperature calcination is 300 - 600 °C, and it is annealed after holding for 2 h; the atmosphere is air or nitrogen; in Step 3, the temperature of the high-temperature calcination and annealing is 300 - 600 °C, and it is annealed after holding for 2 h; the atmosphere is air or nitrogen.

[0022] The present invention also protects a composite catalyst, which is prepared by the preparation method of the composite catalyst as described above.

[0023] The present invention also protects the application of the composite catalyst as described above as a catalyst for the thermal decomposition of ammonium perchlorate.

[0024] Specifically, the addition amount of the composite catalyst is 10% of the total weight of ammonium perchlorate and the composite catalyst, the catalytic heating rate is 10 °C / min, and the temperature range of catalytic heating is 50 - 600 °C.

[0025] Compared with the prior art, the present invention has the following technical effects:

[0026] (Ⅰ) The present invention explores the application of MOF(Fe) and Fe2O3 materials in the catalytic thermal decomposition reaction of AP and obtains good catalytic performance. Compared with the traditional TiO2(P25) catalyst, the high-temperature decomposition peak temperature of the catalytic thermal decomposition of AP is significantly advanced.

[0027] (Ⅱ) The composite catalyst of the present invention has low cost; the composite catalyst of the present invention is easy to prepare, has good repeatability and low price, greatly reduces the preparation cost of the catalyst, and has good application prospects.

[0028] (Ⅲ) The preparation process of the present invention is simple and convenient; this experimental method does not require special experimental instruments, and at the same time, the experimental drugs are all common drugs in the laboratory.

[0029] (Ⅳ) The high-temperature decomposition peak temperature of pure AP is 438 °C; the MOF(Fe)@TiO2 composite catalyst advances the high-temperature decomposition peak temperature of AP to 318 - 337 °C; the Fe2O3-HT@TiO2 composite catalyst advances the high-temperature decomposition peak temperature of AP to 336 - 366 °C; the Fe2O3@TiO2-HT composite catalyst advances the high-temperature decomposition peak temperature of AP to 336 - 366 °C. Description of the Drawings

[0030] Figure 1 Scanning electron microscope SEM images of the MOF(Fe) support (Figure A) and the Fe2O3-HT support (Figure B).

[0031] Figure 2 Transmission electron microscope TEM images of the MOF(Fe) support (Figure A) and the Fe2O3-HT support (Figure B).

[0032] Figure 3 Transmission electron microscope TEM image of MOF(Fe)@TiO2-10c.

[0033] Figure 4 EDS Mapping image of MOF(Fe)@TiO2-10c.

[0034] Figure 5 Transmission electron microscope TEM image of Fe2O3@TiO2-10c-HT.

[0035] Figure 6 EDS Mapping image of Fe2O3@TiO2-10c-HT.

[0036] Figure 7 DSC data graph of the catalytic thermal decomposition of ammonium perchlorate by the MOF(Fe)@TiO2-nc material. Figure 7 In it, a1 represents MOF(Fe)@TiO2-5c / AP; a2 represents MOF(Fe)@TiO2-10c / AP; a3 represents MOF(Fe)@TiO2-20c / AP.

[0037] Figure 8 TG data graph of the catalytic thermal decomposition of ammonium perchlorate by the MOF(Fe)@TiO2-nc material. Figure 8 In it, a1 represents MOF(Fe)@TiO2-5c / AP; a2 represents MOF(Fe)@TiO2-10c / AP; a3 represents MOF(Fe)@TiO2-20c / AP.

[0038] Figure 9 DSC data graph of the catalytic thermal decomposition of ammonium perchlorate by the Fe2O3@TiO2-nc-HT material. Figure 9Among them, b1 represents Fe2O3@TiO2-5c-HT / AP; b2 represents Fe2O3@TiO2-10c-HT / AP; b3 represents Fe2O3@TiO2-20c-HT / AP.

[0039] Figure 10 It is the TG data graph of the catalytic thermal decomposition of ammonium perchlorate by Fe2O3@TiO2-nc-HT material. Figure 10 Among them, b1 represents Fe2O3@TiO2-5c-HT / AP; b2 represents Fe2O3@TiO2-10c-HT / AP; b3 represents Fe2O3@TiO2-20c-HT / AP.

[0040] The following further elaborates on the specific content of the present invention in combination with examples. Specific embodiments

[0041] It should be noted that all materials and equipment in the present invention, without special instructions, are materials and equipment known in the art. In the present invention, MOF(Fe) refers to an iron-based MOF material, which is a basic carrier material; HT refers to high-temperature calcination annealing treatment.

[0042] Metals, metal oxides, metal salts, etc. are often used to catalyze the thermal decomposition of AP. Transition metals and their metal oxides have the characteristics of simple preparation, easy acceptance of electrons, and acceleration of electron transfer, etc., and show excellent performance in catalyzing the decomposition of AP. A large number of studies have been carried out on the catalysis of AP decomposition by transition metals and their metal oxides, especially iron oxide and titanium dioxide catalysts.

[0043] In recent years, the emerging field of metal-organic frameworks or porous coordination polymers has attracted more and more interest. Transition metal (Fe, Co, Ni)-based metal-organic framework materials with controllable structures, large surface areas, and adjustable pore sizes have attracted extensive research interest. In the past decade, these microporous materials have found a variety of applications, including gas storage and separation, sensors, catalysis, and functional materials. In the field of combustion catalysis, MOF is also a potential energetic additive for the thermal decomposition of AP because it is a porous compound composed of organic ligands and catalytic transition metal cations. Therefore, in the direction of combustion catalysis, MOF has received extensive attention due to its advantages such as high specific surface area, high porosity, and adjustable structure. Using MOF as a template, highly dispersed metal and metal oxide nanomaterials with different morphologies can be prepared. Based on this, iron-based MOF materials are prepared, and by virtue of the large specific surface area and rich pore structure of the MOF material, loading other transition metal oxides such as TiO2 is expected to significantly improve the thermal decomposition performance of AP.

[0044] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent transformations made on the basis of the technical solutions of this application fall within the protection scope of the present invention.

[0045] Example 1:

[0046] A preparation method of a carrier material is given in this example. The specific carrier materials are MOF(Fe) carriers and Fe2O3-HT carriers; the specific steps are as follows:

[0047] Preparation of MOF(Fe) carriers: Weigh 1.35 g of FeCl3·6H2O into the polytetrafluoroethylene liner in a 100 ml hydrothermal autoclave, and add 0.83 g of terephthalic acid. Weigh 25 ml of DMF and pour it into the above polytetrafluoroethylene liner and start stirring (at room temperature, the rotation speed is 550 r / min), and stir for 30 min. Put this polytetrafluoroethylene liner into the stainless steel shell of the hydrothermal autoclave and place it in an oven at 150 °C for 2 h. After the temperature drops to room temperature, centrifuge to collect the sample, wash it several times with deionized water, and dry it in an oven at 80 °C to obtain a light reddish-brown solid powder MOF(Fe) sample.

[0048] Preparation of Fe2O3-HT carriers: Put the MOF(Fe) sample in a crucible, place this crucible in a tube furnace, and calcine and anneal it at 450 °C under an air atmosphere to obtain a dark reddish-brown date pit-shaped Fe2O3 sample.

[0049] Figure 1 are the scanning electron microscope SEM images of MOF(Fe) and MOF-induced date pit-shaped Fe2O3. From the pictures, it can be seen that the morphology of MOF(Fe) is regular, showing a date pit shape, with a length of 1-2 μm; the size of Fe2O3 obtained after high-temperature calcination is significantly reduced, the morphology of Fe2O3 is date pit-shaped, with a size of 200-600 nm, and there is a sintering phenomenon.

[0050] Figure 2 are the TEM and HRTEM pictures of MOF(Fe) and MOF-induced date pit-shaped Fe2O3. It can be seen from the high-resolution electron microscope that MOF(Fe) has no lattice fringes and is amorphous. The size of Fe2O3 is significantly reduced, and there is a sintering phenomenon. HRTEM shows the lattice fringes of Fe2O3.

[0051] Example 2:

[0052] A preparation method of a composite catalyst is given in this example. The specific composite catalysts are MOF(Fe)@TiO2 composite catalysts, Fe2O3-HT@TiO2 composite catalysts or Fe2O3@TiO2-HT composite catalysts.

[0053] The preparation method of the MOF(Fe)@TiO2 composite catalyst adopts Step 1.

[0054] The preparation method of the Fe2O3-HT@TiO2 composite catalyst adopts Step 2.

[0055] The preparation method of the Fe2O3@TiO2-HT composite catalyst adopts Step 1 and Step 3.

[0056] Step 1: Prepare the MOF(Fe) support using Example 1; use atomic layer deposition to load TiO2 on the surface of the MOF(Fe) support to form the MOF(Fe)@TiO2 composite catalyst.

[0057] Step 2: Prepare the Fe2O3-HT support using Example 1; then use atomic layer deposition to load TiO2 on the surface of the Fe2O3-HT support to form the Fe2O3-HT@TiO2 composite catalyst.

[0058] Step 3: Under the protection of an atmosphere, the MOF(Fe)@TiO2 prepared in Step 1 is annealed by high-temperature calcination to obtain the Fe2O3@TiO2-HT composite catalyst. In Step 3, the temperature for high-temperature calcination and annealing is 450 °C, and after holding for 2 h, it is annealed; the atmosphere is air or nitrogen.

[0059] The MOF(Fe)@TiO2 and Fe2O3-HT@TiO2 composite catalysts use MOF(Fe) and Fe2O3 as supports respectively, and ALD is used to deposit TiO2. The precursors used are titanium tetraisopropoxide (Ti(OPr)4) and hydrogen peroxide (H2O2), the reaction temperature is 150 °C, the temperature of the precursor Ti(OPr)4 is 45 °C, and the deposition timing is 100 - 100 - 100 - 100 s. The surface reaction proceeds in two steps as follows: ||-OH * + Ti(OCH(CH3)2)4 → ||-OTi(OCH(CH3)2)3 * + HOCH(CH3)2 Step 1 ||-OTi(OCH(CH3)2)3 * + 3H2O2 → ||-OTi(OH)3 * + 3HOCH(CH3)2 + 1.5O2 Step 2

[0060] The specific steps are as follows:

[0061] Step1: Lay the support material (MOF(Fe) or Fe2O3-HT) flat on the sample stage, place this sample stage in the reaction chamber of atomic layer deposition and seal the outlet, use a mechanical vacuum pump to pump out the air in the reaction chamber; set the temperature and heat up. The temperature of the reaction chamber is 150 °C, and the temperature of the titanium source is set to 45 °C.

[0062] Step 2: Introduce an inert carrier gas with a total flow rate of 100 ml / min into the reaction chamber from the inlet of the atomic layer deposition equipment, and evacuate the gas at the outlet with a mechanical pump to stabilize the vacuum degree in the reaction chamber at 10 - 100 Pa. Inject the titanium source into the reaction chamber in a bubbling manner (the carrier gas flow rate of the titanium source path is 40 ml / min, the total carrier gas flow rate is 100 ml / min, and the injection time is 100 s) to enable the titanium source molecules to perform saturated chemical adsorption on the surface of the carrier material. After the titanium source completes saturated adsorption on the carrier surface, stop injecting the titanium source, and blow off the physically adsorbed or excess titanium source from the system with an inert gas flow (the total carrier gas flow rate is 100 ml / min, and the injection time is 100 s).

[0063] Step 3: Similarly, inject the oxidant molecules into the reaction chamber in a bubbling manner to cause a redox reaction between the oxidant molecules and the iron source adsorbed on the carrier surface (the carrier gas flow rate of the H2O2 path is 40 ml / min, the total carrier gas flow rate is 100 ml / min, and the injection time is 100 s). After the reaction is completed, stop injecting the oxidant molecules, and blow off the physically adsorbed or excess oxidant molecules and by-products from the system with an inert gas flow (the total carrier gas flow rate is 100 ml / min, and the injection time is 100 s).

[0064] Step 4: Step 2 and Step 3 are one cycle of titanium dioxide deposition. By increasing the number of cycles of titanium dioxide deposition, different titanium dioxide loadings are controlled to prepare composite catalysts with different numbers of titanium dioxide cycles.

[0065] Figure 3 is the transmission electron microscope (TEM) image of MOF(Fe)@TiO2-10c, Figure 4 is the EDS Mapping image of MOF(Fe)@TiO2-10c, Figure 5 is the transmission electron microscope (TEM) image of Fe2O3@TiO2-10c-HT, Figure 6 is the EDS Mapping image of Fe2O3@TiO2-10c-HT. The above results show that the TiO2 species are highly dispersed. From the STEM and EDS Mapping pictures, it can be seen that the distribution regions of Fe, O, and Ti elements coincide with the ranges on the STEM pictures. The uniform distribution of Fe and Ti elements indicates that the TiO2 deposited by ALD on the carrier is highly dispersed.

[0066] Example 3:

[0067] This example presents the application of the composite catalyst as a catalyst for the thermal decomposition of ammonium perchlorate. The specific catalysts are MOF(Fe)@TiO2 composite catalyst, Fe2O3-HT@TiO2 composite catalyst, or Fe2O3@TiO2-HT composite catalyst; the specific process of this application is described as follows.

[0068] 5 mg of MOF(Fe)@TiO2, Fe2O3-HT@TiO2, and Fe2O3@TiO2-HT materials were separately and uniformly mixed with 45 mg of ultrafine ammonium perchlorate (AP). An appropriate amount of the above-mentioned uniformly mixed samples was taken for thermal decomposition test experiments. The performance of their catalysis of AP was tested by thermogravimetry and differential scanning calorimetry (TG-DSC) in combination. The heating rate was 10 °C / min, and the test temperature range was 50 - 600 °C.

[0069] Figure 7 and Figure 8 are the DSC data and TG data graphs of the catalysis of ammonium perchlorate thermal decomposition by the MOF(Fe)@TiO2-nc material. It can be seen from the DSC curve that the high-temperature decomposition peak temperatures of MOF(Fe)@TiO2-5c / AP and MOF(Fe)@TiO2-10c / AP are both 330 °C; the high-temperature decomposition peak temperature of MOF(Fe)@TiO2-20c / AP is 337 °C. The results of the TG curve are consistent with the DSC results.

[0070] Figure 9 and Figure 10 are the DSC data and TG data graphs of the catalysis of ammonium perchlorate thermal decomposition by the Fe2O3@TiO2-nc-HT material. It can be seen from the DSC curve that the high-temperature decomposition peak temperature of Fe2O3@TiO2-5c-HT / AP is 344 °C; the high-temperature decomposition peak temperature of Fe2O3@TiO2-10c-HT / AP is 336 °C; the high-temperature decomposition peak temperature of Fe2O3@TiO2-5c-HT / AP is 338 °C; the results of the TG curve are consistent with the DSC results.

[0071] It should be noted that the high-temperature decomposition peak temperatures of Fe2O3-HT@TiO2 / AP and Fe2O3@TiO2-HT / AP with the same deposition cycle are the same, that is, the high-temperature decomposition peak temperature of Fe2O3-HT@TiO2-5c / AP is 344 °C; the high-temperature decomposition peak temperature of Fe2O3-HT@TiO2-10c / AP is 336 °C; the high-temperature decomposition peak temperature of Fe2O3-HT@TiO2-5c / AP is 338 °C; the high-temperature decomposition peak temperature of pure AP is 438 °C. The results of the TG curve are consistent with the DSC results.

[0072] After depositing TiO2 on the Fe2O3-HT support induced by MOF(Fe), its catalytic performance is improved, and the activity reaches the best when the deposition cycle is 10. The experiment of depositing TiO2 on the Fe2O3-HT support also proves from the side that the activity of the Fe2O3-TiO2 interface sites is significantly better than that of the isolated Fe2O3 sites.

[0073] Table 1 shows the peak temperatures of AP decomposition catalyzed by different catalysts.

[0074] From Figure 7 , Figure 8 , Figure 9 , Figure 10 and Table 1, it can be seen that the peak temperature of high-temperature decomposition of pure AP is 438 °C; the MOF(Fe)@TiO2 composite catalyst advances the peak temperature of high-temperature decomposition of AP to 318 - 337 °C; the Fe2O3-HT@TiO2 composite catalyst advances the peak temperature of high-temperature decomposition of AP to 336 - 366 °C; the Fe2O3@TiO2-HT composite catalyst advances the peak temperature of high-temperature decomposition of AP to 336 - 366 °C.

[0075] Table 1 Peak Temperatures of AP Decomposition Catalyzed by Different Catalysts

[0076] Catalyst / AP Peak temperature of high-temperature decomposition of AP (°C) Advance degree of the highest decomposition peak temperature ΔT <![CDATA[MOF(Fe)@TiO2-5c / AP]]> 330 108 <![CDATA[MOF(Fe)@TiO2-10c / AP]]> 330 108 <![CDATA[MOF(Fe)@TiO2-20c / AP]]> 337 101 <![CDATA[Fe2O3@TiO2-5c-HT / AP]]> 344 94 <![CDATA[Fe2O3@TiO2-10c-HT / AP]]> 336 102 <![CDATA[Fe2O3@TiO2-20c-HT / AP]]> 338 100 Without catalyst (pure AP) 438 -

Claims

1. Use of a composite catalyst as a catalyst for thermal decomposition of ammonium perchlorate, characterized in that, The composite catalyst described above is a MOF(Fe)@TiO2 composite catalyst, an Fe2O3-HT@TiO2 composite catalyst, or an Fe2O3@TiO2-HT composite catalyst; The preparation method of the MOF(Fe)@TiO2 composite catalyst adopts Step 1; The preparation method of the Fe2O3-HT@TiO2 composite catalyst adopts Step 2; The preparation method of the Fe2O3@TiO2-HT composite catalyst adopts Step 1 and Step 3; Step 1: Use atomic layer deposition to load TiO2 on the surface of the MOF(Fe) support to form a MOF(Fe)@TiO2 composite catalyst; Step 2: Under the protection of an atmosphere, the MOF(Fe) support is annealed by high-temperature calcination to obtain an Fe2O3 support induced by MOF(Fe), that is, an Fe2O3-HT support; then use atomic layer deposition to load TiO2 on the surface of the Fe2O3-HT support to form an Fe2O3-HT@TiO2 composite catalyst; Step 3: The MOF(Fe)@TiO2 prepared in Step 1 is annealed by high-temperature calcination under the protection of an atmosphere to obtain an Fe2O3@TiO2-HT composite catalyst.

2. The application according to claim 1, characterized in that The addition amount of the composite catalyst described above is 10% of the total weight of ammonium perchlorate and the composite catalyst, the catalytic heating rate is 10 °C / min, and the temperature range for catalytic heating is 50 - 600 °C.

3. The application according to claim 1, characterized in that In Step 1, the particle size of the MOF(Fe) support is 1 - 2 μm; in Step 2, the particle size of the Fe2O3-HT support is 200 - 600 nm.

4. The application according to claim 1, wherein In Step 1 and Step 2, the specific process of loading TiO2 by atomic layer deposition is as follows: Step1: Lay the support material flat on the sample stage, place this sample stage in the reaction chamber of atomic layer deposition and seal the outlet, and use a mechanical vacuum pump to evacuate the air in the reaction chamber; set the temperature and heat up, the temperature of the reaction chamber is 150 °C, and the temperature of the titanium source is set to 45 °C; Step2: Introduce an inert carrier gas with a total flow rate of 50 - 150 ml / min into the reaction chamber from the inlet of the atomic layer deposition equipment, and evacuate at the outlet with a mechanical pump to make the vacuum degree in the reaction chamber stable at 10 - 100 Pa; inject the titanium source into the reaction chamber by bubbling, so that the titanium source molecules perform saturated chemical adsorption on the surface of the support material. After the titanium source completes saturated adsorption on the support surface, stop injecting the titanium source, and use an inert gas flow to blow away the physically adsorbed or excess titanium source from the system; Step3: Similarly, inject oxidant molecules into the reaction chamber by bubbling, so that the oxidant molecules react with the iron source adsorbed on the support surface through redox reaction; after the reaction is completed, stop injecting the oxidant molecules, and use an inert gas flow to blow away the physically adsorbed or excess oxidant molecules and by-products from the system; Step4: Steps Step2 and Step3 are one cycle of titanium dioxide deposition; by increasing the number of cycles of titanium dioxide deposition, different titanium dioxide loadings are controlled to prepare composite catalysts with different numbers of titanium dioxide cycles.

5. The application according to claim 4, characterized in that The carrier material is MOF(Fe) carrier in the first step and Fe2O3-HT carrier in the second step; the titanium source is titanium tetraisopropoxide; the oxidant is hydrogen peroxide; the inert carrier gas is high-purity nitrogen or high-purity argon.

6. The application according to claim 1, wherein In the first step, the MOF(Fe) carrier is prepared by hydrothermal method. The specific process is as follows: Put FeCl3•6H2O in the polytetrafluoroethylene liner in the hydrothermal autoclave, add terephthalic acid, then pour DMF into the polytetrafluoroethylene liner and start stirring for 30 min; put this polytetrafluoroethylene liner into the stainless steel shell of the hydrothermal autoclave and place it in an oven at 150 °C for heat preservation for 2 h; after the temperature drops to room temperature, centrifuge to collect the sample, wash it with deionized water, and dry it in an oven at 80 °C to obtain the MOF(Fe) carrier.

7. The application according to claim 1, characterized in that In the second step, the temperature of the high-temperature calcination is 300-600 °C, and it is annealed after heat preservation for 2 h; the atmosphere is air or nitrogen; in the third step, the temperature of the high-temperature calcination and annealing is 300-600 °C, and it is annealed after heat preservation for 2 h; the atmosphere is air or nitrogen.

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