CN112108145A - Alumina-supported iridium cluster catalyst and preparation and application thereof - Google Patents

Abstract

The invention relates to an alumina supported iridium cluster catalyst and preparation and application thereof. Specifically, the content of iridium is 0.1-5% of the total mass of the catalyst, the iridium is highly dispersed on alumina in the form of clusters, and the cluster size is 0.5-5 nm. The iridium cluster serving as a unique catalytic activity center is suitable for room-temperature formaldehyde elimination and catalytic decomposition of NJ-DT-3, shows excellent catalytic activity, can be used for completely catalytically oxidizing high-concentration formaldehyde (180ppm) into carbon dioxide and water at room temperature, and has higher reaction rate when being used for decomposition reaction of NJ-DT-3.

Description

Alumina-supported iridium cluster catalyst and preparation and application thereof

Technical Field

The invention relates to an alumina supported iridium cluster catalyst, and preparation and application thereof, which can be used for room temperature elimination and NJ-DT-3 decomposition reaction of typical volatile organic pollutants formaldehyde.

Background

Volatile Organic Compounds (VOCs) are the main air pollutants, and formaldehyde (HCHO) is one of the typical VOCs, and the problem of air pollution caused by the VOCs is becoming more serious and more important. On the one hand, outdoor formaldehyde is mainly derived from industrial exhaust gas and automobile exhaust emission. Recent research shows that the discharged formaldehyde can react with sulfur dioxide to generate hydroxymethanesulfonate, which is an important source of PM2.5, so that the formaldehyde is the main cause of haze weather in winter in China. On the other hand, indoor formaldehyde is mainly released from building and decorative and finishing materials such as adhesives, plywood, paints, diluents, and the like. Formaldehyde is a highly toxic substance and is a main indoor air pollutant, and long-term exposure to formaldehyde can cause symptoms such as headache, nausea, allergy and the like, and even cause teratogenesis and carcinogenesis. Therefore, the elimination of formaldehyde, especially at room temperature, has important significance for effectively improving the air quality, solving the problem of air pollution and protecting the human health.

At present, the commonly used method for eliminating formaldehyde at room temperature mainly comprises an adsorption method, a photocatalysis method and a catalytic oxidation method [ ChemSusChem,2013,6,578-]. The adsorption method generally adopts porous materials as adsorbents, and carbon-based adsorbents (such as activated carbon, carbon fibers and the like) and porous oxides (such as activated alumina, silica gel and the like) are commonly used. Although the formaldehyde scavenger is low in price and good in adsorption capacity, the formaldehyde scavenger is limited in adsorption amount and is easy to reach saturation, so that the formaldehyde can not be continuously eliminated. The photocatalysis method mostly adopts ZnO and TiO₂The adsorbed formaldehyde is irradiated by the photocatalystOxidation to CO₂And H₂However, the generation of CO and other by-products is often accompanied in the catalytic process, and the cost of the used ultraviolet light source is high and the service life is short, so that the wide application of the method is limited. The catalytic oxidation method uses metal or its oxide as catalyst, oxygen in air as oxidant, and converts formaldehyde into nontoxic CO₂And H₂And O. The method has the advantages of low energy consumption, high efficiency, environmental friendliness and the like, and is paid much attention by researchers.

In the formaldehyde oxidation reaction, a supported noble metal catalyst system generally shows excellent catalytic performance, and at present, Pt, Pd, Au and the like are researched more. He et al reported that alkali metal ion (Li, Na, K) modified Pt/TiO₂Catalyst, found 2% Na-1% Pt/TiO₂The catalyst has excellent catalytic performance in formaldehyde oxidation reaction, and can completely oxidize 600ppm formaldehyde at room temperature [ Angew. chem. int. Ed.,2012,51,9628-]. Zhou et al for CeO of different morphologies₂The performance of the supported Pd catalyst in the formaldehyde oxidation reaction is compared and researched, and CeO is found₂The catalytic activity of the supported noble metal Pd is higher than that of octahedron and rodlike CeO when the supported noble metal Pd is in a cubic shape and the exposed crystal face is a (100) crystal face₂Has high catalytic activity of formaldehyde oxidation when being used as a carrier [ Environ. Sci. Technol.2015,49,8675-]. Iridium, which is an important member of platinum group metals, exhibits excellent catalytic activity in PROX, water vapor shift, and other reactions, while it is less studied in formaldehyde oxidation reactions. Recently, Li et al prepared Ir/TiO by the excess impregnation method₂The catalyst has lower activity in the catalytic formaldehyde oxidation reaction, the catalytic activity is greatly improved after the catalyst is further modified by Na ions, formaldehyde can be completely eliminated at room temperature, and the addition of the Na ions is considered by the catalyst to promote the reduction of titanium oxide at the metal-carrier interface, increase the oxygen vacancy on the carrier surface and promote the activation of water, so that the catalytic performance is improved [ ACS Catal.2018,8,11377-]. Gao et al use hydrogenated TiO₂(i.e., NaBH)₄Pre-reduction treatment) as a carrier, loading Ir and then catalyzing formaldehyde oxidation reaction to find hydrogenated TiO₂Has abundant oxygen vacancy and surface hydroxyl group to catalyzeThe activation activity is obviously improved, but the conversion rate is still less than 20% at room temperature, and the activity is lower [ New J.chem.,2018,42, 18381-18387-]. At present, reducible TiO is selected in all reported Ir catalyst systems₂As a carrier, inert Al₂O₃The Ir-based catalyst loaded on the carrier is not reported to be used for formaldehyde oxidation reaction.

The propellant provides an energy source for the thrust of the rocket engine, can directly influence the flight performance of an aircraft, and is very important for the rocket engine. Conventional propellants are largely divided into solid propellants and liquid propellants. The solid propellant exists in a rocket engine in a solid form, is easy to store and has high density, but has low specific impulse and poor controllability, and can not be started and stopped repeatedly, while the liquid propellant is easy to leak although the flow is convenient to control, and has low safety coefficient, so that the solid propellant and the liquid propellant can not completely meet the requirements on the safety and the high efficiency of the propellant. In the continuous search of novel propellants, gel propellants are produced, and the gel propellants are considered to be propellants with great application prospects in the field of future aerospace due to the advantages of both solid propellants and liquid propellants. The gel propellant can be rapidly decomposed under the action of the catalyst to generate a large amount of gas and release heat, so that the rapid conversion from chemical energy to kinetic energy is realized. At present, the most typical catalyst for catalyzing the decomposition of gel propellants is Al₂O₃Supported Ir catalysts, e.g. catalyst No. Shell405 U.S. Pat. No. 4,124,538]However, Ir loadings of up to 20-40 wt% were achieved. Ir as a rare noble metal and a high-grade strategic material needs to be optimized by a new catalyst synthesis method so as to reduce the dosage of Ir and reduce the dependence on Ir reserves. It is subjected to monoatomic dispersion into an effective method [ ZL201218006496.5]However, during the decomposition of the propellant, it is possible that the Ir particles aggregate and grow due to the higher specific surface energy of the monoatomic atoms [ angelw.chem., int.ed.2012,51,5929]. Up to now, Ir-based catalysts mainly adopt an impregnation method, precursors are primarily dispersed on the surface of a carrier in an ion form, and the formation of a catalytic center (Catalysis Today,2012,185,198) with nonuniform dispersion is difficult to avoid in the post-treatment process]Manufacture ofThe proportion of the effective components is low, and most Ir metal is wasted.

The invention firstly uses inert carrier Al₂O₃The supported Ir cluster catalyst with uniform size is applied to the catalytic decomposition of propellant NJ-DT-3.

Disclosure of Invention

The invention aims to provide an inert carrier Al₂O₃A supported cluster Ir catalyst and preparation and application thereof.

In order to achieve the purpose, the invention adopts the technical scheme that:

a cluster Ir catalyst, which is made of non-reducible Al₂O₃Is a carrier, noble metal Ir is an active component, the Ir content accounts for 0.1-5% of the total mass of the catalyst, and Al is added₂O₃The above-mentioned components are highly dispersed in the form of clusters, and the size of the clusters is 0.5-5 nm.

The catalyst is prepared by a colloid formation-deposition loading two-step method, and the specific process comprises the following steps: ir sol prepared by adopting a low-carbon alcohol reduction method as a precursor, and then the Ir sol is added into Al drop by drop under the condition of violent stirring₂O₃And (3) reacting in the carrier suspension for 3h, standing and aging for 1h, filtering and washing while the carrier suspension is hot, and drying at 80 ℃ for 12h to obtain the target catalyst.

The Ir cluster sol is prepared by the low carbon alcohol reduction method, and the specific process is as follows: dissolving chloroiridic acid in 50-100 mL of low-carbon alcohol to prepare L with the concentration of 3.9-39 mmol^-150-100 mL of 0.03-0.75 mol L of the solution (a)^-1And stirring NaOH or KOH low-carbon alcohol solution at room temperature for 0.5-3 h until the solution is uniformly mixed, transferring the solution into an oil bath at the temperature of 100-160 ℃, and reacting for 1-3 h under the protection of argon or nitrogen atmosphere to obtain the iridium cluster sol.

The lower alcohol is one or more of methanol, ethylene glycol, glycerol and 1, 4-butanediol.

The catalyst is reduced in a hydrogen atmosphere, and the gas composition is 20-100 vol% H₂He is balance gas, and reduction is carried out for 0.5-2 h at 200-300 ℃.

The catalyst can be used for catalyzing formaldehyde oxidation reaction at room temperature, and has the composition of 180ppm formaldehyde and 20 vol.% O₂Former of He equilibriumRelative humidity of material gas is 50%, and space velocity is 3X 10⁴mL g_cat ^-1h^-1And introducing the mixture into a normal-pressure fixed bed reactor filled with a catalyst, and testing the conversion rate of formaldehyde at the temperature of between 20 and 80 ℃.

The catalyst can be used for catalytic decomposition reaction of NJ-DT-3 propellant and has higher reaction rate.

Compared with the prior art, the invention has the substantial characteristics that:

1. the catalyst prepared by the method has the advantages that the active component Ir is dispersed in clusters with uniform size, and the catalytic activity of the catalyst is improved and the dosage of the noble metal Ir is reduced.

2. The carrier used for preparing the catalyst is inert alumina, the specific surface area is large, Ir dispersion is facilitated, and Ir is taken as the only active center.

3. The Ir catalyst loaded by the inert carrier alumina has high activity, can completely oxidize the formaldehyde with high concentration of 180ppm at room temperature, and realizes the breakthrough of the performance of efficiently eliminating the formaldehyde by taking the non-reducible oxide as the Ir catalyst loaded by the carrier for the first time.

4. The decomposition reaction rate of the cluster Ir catalyst catalyzed NJ-DT-3 propellant prepared by the method is higher than that of Ir/Al propellant prepared by other preparation methods₂O₃A catalyst.

Drawings

FIG. 1 is a schematic representation of Ir/Al prepared in example 1 and comparative examples 1 and 2₂O₃XRD pattern of catalyst.

FIG. 2 is Ir/Al prepared in example 1₂O₃Catalyst HAADF-STEM diagram and particle size statistical diagram.

FIG. 3 is a graph of Ir/Al prepared in example 1 of the present invention and comparative examples 1 and 2₂O₃The catalytic performance of the catalyst for catalyzing formaldehyde oxidation is compared with a graph.

FIG. 4 is a graph of Ir/Al prepared in examples 1, 12, 13, 14 and 15 of the present invention₂O₃The oxidation performance of the catalyst catalyzing formaldehyde is shown in the test chart.

FIG. 5 is a graph of Ir/Al prepared in comparative example 3 of the present invention₂O₃Comparison graph of formaldehyde oxidation performance catalyzed by catalyst。

FIG. 6 is a graph of Ir/Al prepared in example 1 of the present invention and comparative examples 1 and 2₂O₃Catalyst stability test chart.

FIG. 7 is a schematic view of Ir/Al prepared by different methods₂O₃The decomposition rates of the catalyst NJ-DT-3 are compared.

Detailed Description

The following examples are intended to illustrate the invention in more detail and are not intended to limit the scope of the invention.

Example 1:

dissolving 1.0g of chloroiridic acid in 50mL of ethylene glycol, wherein the concentration of metallic iridium ions in the solution is 39mmol L^-150mL of the solution was added at a concentration of 0.25mol L^-1Adding sodium hydroxide and ethylene glycol solution into the solution, stirring the solution at room temperature for 0.5h, transferring the solution into an oil bath at 160 ℃, stirring the solution for reaction for 1h under the protection of argon atmosphere to obtain Ir nanosol, measuring 4.0mL of Ir nanosol, and dropwise adding the Ir nanosol into the vigorously stirred Al nanosol with the particle size of 10-12 nm₂O₃Reacting in the carrier suspension at 80 ℃ for 3h, aging for 1h, filtering and washing while the solution is hot, and drying at 80 ℃ for 12h to obtain 1.5 wt.% Ir/Al₂O₃Catalyst, labeled 1.5 IrAl-NP. The catalyst was at 20 vol.% H₂/He(H₂Volume fraction of 20%, He is equilibrium gas, hereinafter both expressed in this way) was reduced at 300 ℃ for 0.5h in an atmosphere and then subjected to XRD and STEM characterization, the results are shown in fig. 1 and 2. The XRD result shows that no diffraction peak of Ir species is found in the spectrogram, and the Ir species is on the carrier Al₂O₃A highly dispersed state is exhibited. The STEM electron micrograph shows that the average particle size of the Ir nanoparticles is 1.1nm, the particle size distribution range is narrow (0.8-2 nm), and the size is uniform. 1.5IrAl-NP catalyst was used for evaluation of the formaldehyde oxidation reaction. The test conditions were that the catalyst amount was 100mg, the composition of the reaction feed gas was 180ppm HCHO, 20 vol.% O₂He is balance gas, relative humidity is 50%, and total flow is 50mL min^-1(STP) at a mass space velocity of 3X 10⁴mL g_cat ^-1h^-1And carrying out temperature programming activity test on the catalyst at a temperature range of 20-80 ℃. Catalyst before reaction testing at 20 vol.% H₂Reducing for 0.5h at 300 ℃ in a He atmosphere. The results are shown in FIG. 3, which shows the methodThe 1.5IrAl-NP catalyst prepared by the method has excellent catalytic performance in formaldehyde oxidation reaction, and the formaldehyde conversion rate is kept at 100% within the temperature range of 20-80 ℃.

Examples 2 to 11: the preparation method is the same as example 1, and the specific conditions are shown in the following table:

example 13:

compared with example 1, except that the amount of Ir nanosol used was 2.7mL Ir nanosol, the remaining steps were consistent, and 1.0 wt.% Ir/Al was obtained₂O₃Catalyst, labeled 1.0 IrAl-NP.

Example 14:

compared with example 1, except that the amount of Ir nanosol used was 1.4mL Ir nanosol, the remaining steps were identical, and 0.5 wt.% Ir/Al was obtained₂O₃Catalyst, labeled 0.5 IrAl-NP.

Example 15:

compared with example 1, except that the amount of Ir nanosol used was 14mL Ir nanosol, the remaining steps were consistent, and finally 5 wt.% Ir/Al was obtained₂O₃Catalyst, labeled 5 IrAl-NP.

Example 16:

compared with example 1, except that the amount of Ir nanosol used was 0.28mL Ir nanosol, the remaining steps were consistent, and 0.1 wt.% Ir/Al was obtained₂O₃Catalyst, labeled 0.1 IrAl-NP.

Comparative example 1:

al preparation by deposition precipitation method₂O₃A supported Ir catalyst. 1.0g of Al with the particle size of 10-12 nm₂O₃Dispersing in 100mL ultrapure water to form a suspension, and stirring vigorously for 3.0mL min^-1Was added dropwise at a rate of 91uL of 164mg mL^-10.2mol L of chloroiridic acid solution (2)^-1Adjusting the pH value to 9.2 with NaOH, reacting at 80 ℃ for 3h, aging for 1h, filtering and washing while hot, and drying at 80 ℃ for 12h to obtain 1.5 wt.% Ir/Al₂O₃Catalyst, labelled 1.5 IrAl-DP.

Comparative example 2:

al preparation by adopting equal-volume impregnation method₂O₃A supported Ir catalyst. Diluting 91uL of 164mg mL chloroiridic acid solution to 0.6mL by using ultrapure water, and dropwise adding the diluted solution to 1.0g of Al with the particle size of 10-12 nm₂O₃Adding the powder into a glass rod, stirring the mixture evenly, and drying the mixture in an oven at the temperature of 80 ℃ for 12 hours and 1.5 wt.% of Ir/Al₂O₃Catalyst, labelled 1.5 IrAl-IMP.

Examples 17 to 20 were carried out to examine the influence of different influencing factors on the performance and stability of the catalysts prepared. And (3) carrying out formaldehyde elimination performance test on the catalyst by adopting a normal-pressure fixed bed micro-reaction evaluation device. The test conditions were that the catalyst amount was 100mg, the composition of the reaction feed gas was 180ppm HCHO, 20 vol.% O₂He is balance gas, relative humidity is 50%, and total flow is 50mL min^-1(STP) at a mass space velocity of 3X 10⁴mL g_cat ^-1h^-1. And carrying out temperature programming activity test on the catalyst at a temperature range of 20-80 ℃. Catalyst before reaction testing at 20 vol.% H₂Reducing the mixture for 0.5h at 300 ℃ in an atmosphere of/He, and then blowing He gas to reduce the temperature to room temperature. During the test, samples were taken every 20min, 1h at each temperature point, 3 times. The concentration of the reaction equilibrium gas was detected by FID detector in the chromatogram. Because the HCHO concentration in the feed gas is ppm level, trace CO is obtained₂Before entering the FID detector, the hydrogen is hydrogenated by a nickel converter, and all the hydrogen is converted into CH₄And then detecting.

The HCHO conversion was calculated as follows:

HCHO Conversion(％)＝[CO₂]/[CO₂]^A×100％

wherein: [ CO ]₂]^ACompletely convert formaldehyde in the raw material gas into CO₂Time corresponding CH₄Chromatographic peak area

[CO₂]For balancing CO in gas under different reaction temperature conditions₂Corresponding CH₄Chromatographic peak area.

Example 17: investigating the influence of the preparation method on the formaldehyde elimination performance of the catalyst

100mg of the catalyst prepared in example 1 and comparative examples 1 and 2 was packed in a quartz reaction tube, and the catalyst was at 20 vol.% H before the reaction₂Reducing for 0.5h at 300 ℃ under the atmosphere of/He, purging helium to room temperature, and using the pretreated catalyst for formaldehyde oxidation reaction evaluation. The results are shown in fig. 3, which shows that the 1.5Ir/Al-NP catalyst prepared by the colloid-deposition method in example 1 shows the highest formaldehyde elimination performance, the formaldehyde conversion rate is kept at 100% within the temperature test range of 20-80 ℃, while the 1.5Ir/Al-DP catalyst with the same Ir loading prepared by the deposition-precipitation method has the conversion rate of 57% at room temperature and 83% at 80 ℃, the 1.5Ir/Al-IMP catalyst prepared by the impregnation method has the worst formaldehyde elimination performance, and the formaldehyde conversion rate is still below 40% at 80 ℃. Therefore, the 1.5Ir/Al-NP catalyst prepared by the preparation method of the catalyst, namely the colloid-deposition method has obvious elimination performance advantage in the formaldehyde elimination reaction.

Example 18: investigating the influence of noble metal Ir loading on the formaldehyde elimination performance of the catalyst

The loading capacity of 100mg Ir is 0.1-5 wt% Ir/Al₂O₃The catalyst was packed in a quartz reaction tube at 20 vol.% H before reaction₂Reducing for 0.5h at 300 ℃ under the atmosphere of/He, purging helium to room temperature, and using the pretreated catalyst for formaldehyde oxidation reaction evaluation. The results are shown in fig. 4, which shows that the catalytic formaldehyde oxidation performance is also increased with the increase of the Ir loading, indicating that the Ir nanoclusters are the active centers of catalytic reaction during the catalytic formaldehyde elimination process.

Example 19: investigating the influence of the pretreatment atmosphere on the formaldehyde elimination performance of the catalyst

Different from example 1, catalyst 1.5IrAl-NP was 20 vol.% O₂Pre-reducing for 0.5h at 300 ℃ under the atmosphere of/He, purging with helium to room temperature, and then evaluating the formaldehyde oxidation reaction. The results are shown in FIG. 5, which shows that the catalytic activity is greatly reduced after the treatment in the oxygen atmosphere, and the conversion rate at room temperature is less than 20%, thus showing that the pretreatment atmosphere of the catalyst has an important influence on the catalytic activity.

Example 20: investigating the influence of the preparation method of the catalyst on the stability of the catalytic formaldehyde oxidation reaction

80mg of the catalyst prepared in example 1 and comparative examples 1 and 2 was packed in a quartz reaction tube, and the catalyst was at 20 vol.% H before the reaction₂Reducing for 0.5h at 300 ℃ under the atmosphere of/He, blowing helium to room temperature, and using the pretreated catalyst for evaluating the oxidation stability of formaldehyde. The results are shown in fig. 6, which shows that the three catalysts prepared by the colloid-deposition method, the precipitation method and the equal-volume impregnation method all have stable reaction performance in the formaldehyde oxidation reaction, but the catalytic activities show obvious differences, the formaldehyde elimination performance is the highest on the 1.5Ir/Al-NP catalyst, the last time on the 1.5Ir/Al-DP and the worst on the 1.5Ir/Al-IMP catalyst, and the activity sequence is consistent with the results in fig. 3.

Example 21 catalytic NJ-DT-3 decomposition reaction Rate testing

Catalyst of example 1 and comparative examples 1 and 2 at 20 vol.% H₂Reducing the mixture for 0.5h at 300 ℃ in a hydrogen atmosphere of/He, then filling the mixture into a reactor, adding a certain amount of NJ-DT-3 raw material, and recording the reaction time after the test temperature is reached. The rate of decomposition reaction of NJ-DT-3 can be expressed in TOF, i.e., the amount of reactant converted per unit time per unit active site, and is calculated as follows:

wherein, C_DT-3For the NJ-DT-3 conversion, t is the reaction time after the reaction temperature has been reached, M_Ir/DT-3Is the molar ratio of Ir in the added catalyst to the raw material NJ-DT-3.

The results are shown in FIG. 7, which shows that the 1.5IrAl-NP catalyst prepared by the preparation method of the invention has higher reaction rate for catalyzing the decomposition of NJ-DT-3 than the catalyst prepared by the traditional deposition precipitation method and the equal volume impregnation method.

Claims (10)

1. An alumina-supported iridium cluster catalyst characterized in that: alumina is used as a carrier, noble metal iridium is used as an active component, the iridium content is 0.1-5% of the total mass of the catalyst (preferably, the iridium content is 0.5-2%), the noble metal iridium is highly dispersed on the alumina carrier in a cluster form, and the cluster size is 0.5-5 nm (preferably, the cluster size is 0.8-2 nm).

2. The preparation method of the catalyst according to claim 1, which is characterized by adopting a two-step synthesis method of cluster colloid formation and subsequent deposition and loading, and comprises the following specific steps: firstly, iridium sol is obtained by a low-carbon alcohol reduction method and is used as a precursor, then the iridium sol is dripped into alumina carrier low-carbon alcohol suspension, the mixture is stirred, kept stand and aged, so that nanoclusters in the iridium sol are deposited on carrier alumina, and then the target catalyst is obtained through the steps of filtering, washing and drying.

3. The preparation method of the catalyst according to claim 2, wherein the precursor iridium sol is prepared by a low carbon alcohol reduction method, and the specific process comprises the following steps: dissolving noble metal chloroiridic acid in 50-100 mL of low carbon alcohol to prepare a solution, wherein the concentration of metal iridium ions in the solution is 3.9-39 mmol L^-1Adding 50-100 mL of L with the concentration of 0.03-0.75 mol into the solution^-1Stirring the NaOH and/or KOH low-carbon alcohol solution at room temperature for 0.5-3 h, uniformly mixing, transferring into an oil bath at 100-160 ℃, and reacting for 1-5 h under the protection of argon or nitrogen atmosphere to obtain the iridium cluster sol.

4. The method for preparing a catalyst according to claim 2 or 3, wherein the lower alcohol is one or more of methanol, ethylene glycol, glycerin, and 1, 4-butanediol.

5. A process for preparing a catalyst according to claim 2, wherein: the stirring speed is 500-1000 rpm, the reaction time is 2-6 h, the aging temperature is 25-80 ℃, and the aging time is 1-5 h.

6. A process for preparing a catalyst according to claim 2, wherein: the drying temperature of the catalyst is 60-100 ℃, and the drying time is 12-48 h.

7. A process for preparing a catalyst according to claim 2, wherein: the mass concentration of the alumina carrier low-carbon alcohol suspension is 2-10 g/L, and the particle size of the used alumina is 10-12 nm.

8. Use of the catalyst of claim 1 for formaldehyde elimination.

9. Use of a catalyst according to claim 8, wherein: the raw material gas comprises 30-300 ppm of formaldehyde and 5-40 vol.% of O₂He balance gas, relative air humidity of 0-75%, space velocity of 6X 10³～6×10⁵mL g_cat ^-1h^-1A normal-pressure fixed bed reactor is adopted, the testing temperature is 20-80 ℃, and room temperature is preferred.

10. Use of the catalyst of claim 1 for NJ-DT-3 propellant catalyzed decomposition reactions with a high reaction rate.

Images