Preparation method and application of transition metal oxide catalyst for efficient catalytic decomposition of N2O pollution

Abstract

The present application mainly relates to the technical field of pollution gas prevention and treatment, and particularly relates to a preparation method and application of a transition metal oxide catalyst for high-efficiency catalytic decomposition of N2O pollution. The preparation method is as follows: a specific surfactant is dissolved in deionized water, inorganic acid is added, stirring is performed until the mixture is miscible, transition metal nitrate is added, reaction is performed until a gel is formed, drying is performed to obtain a dry gel, calcination is performed, and the target catalyst is obtained. The prepared catalyst 10TX-Co3O4 has extremely high low-temperature catalytic activity, and the catalytic conversion rate of N2O reaches 90% at 300 DEG C; and under the condition of coexistence of O2, NO x , H2O impurity gas and N2O (simulated tail gas of a nitric acid plant), the catalyst still has high catalytic activity and stability (81% conversion rate at 400 DEG C). The present application provides a plurality of high-activity low-temperature catalysts for catalytic decomposition of N2O, and provides a wider train of thought for subsequent design of the catalyst and effective development and utilization of the additives.

Description

TECHNICAL FIELD

[0001] The present application mainly relates to the technical field of pollution gas prevention and treatment, and particularly relates to a preparation method and application of a transition metal oxide catalyst for efficiently catalytically decomposing N2O pollution. BACKGROUND

[0002] According to investigations, although the content of nitrous oxide (N2O) in the atmosphere is very low, the greenhouse effect caused by N2O is 298 times that of carbon dioxide, and N2O is the third strongest greenhouse gas after CO2 and CH4, which has a great impact on the environment. With the rise of the industrial revolution, human activities, especially industrial production and automobile exhaust, have emitted a large amount of N2O, and the amount of emission is increasing day by day. Therefore, the elimination of N2O has attracted more and more attention, and it is urgent to seek an efficient and low-energy consumption decomposition method. At present, in the standard method for eliminating N2O, the direct catalytic decomposition method has the most application prospects due to its low cost, simple operation, high efficiency, no reducing agent, no secondary pollution and other advantages.

[0003] For the catalyst for directly catalytically decomposing N2O, it is found that in the transition metal oxide catalyst, especially Co3O4, it has important significance and research potential in the catalytic decomposition of N2O due to its economy, good hydrothermal stability, high catalytic activity, easy change of structure and physicochemical properties and other characteristics. In the current research on improving the performance of cobalt-based catalysts for catalyzing N2O decomposition, various modification methods have been proposed, which can cause changes in structure and morphology by changing the preparation method or adding different additives, and finally greatly affect the catalytic performance of Co3O4. In addition to catalytic activity, the resistance and stability to impurity gases (H2O, NO x , O2) are important properties for industrial production, so the research focus of direct catalytic N2O decomposition is mainly to synthesize catalysts with high catalytic performance in the actual exhaust gas environment.

[0004] Currently, the main preparation method of cobalt-based catalysts is co-precipitation, through which catalysts with good activity can be obtained by a simple method. It has been reported that when Co3O4 catalysts are prepared by co-precipitation (Ohnishi et al., Catalysis Today. 2007, 120, 145-150), different factors such as precipitants, stirring temperature and precipitation time have a significant impact on the catalytic decomposition of N2O on the catalyst, thereby affecting the structure of the Co3O4 catalyst. MgCo2O4 spinel catalysts for the decomposition of N2O were prepared by solution combustion and co-precipitation methods (Zamudio et al., Industrial and Engineering Chemistry Research. 2011, 50, 2622-2627), and the results showed that the catalyst prepared by co-precipitation method exhibited higher activity due to its larger specific surface area and stronger ability to enrich oxygen species on the surface. At the same time, most researchers add additives to Co3O4 by co-precipitation method to obtain a series of catalysts with excellent performance, such as Bi 0.02 Co (Tursun et al., Catalysis Communications. 2015, 65, 1-5), Pb 0.04 Co (Yu et al., Applied Catalysis B: Environmental. 2016, 185, 110-118), Gd 0.06 Co (Xiong et al., Environmental Science and Technology, 2021, 55, 13335-13344) and Ag 0.04 Co (Tursun et al., Catalysis Communications. 2015, 65, 1-5). In these catalysts, the improvement of catalyst activity depends on the electronic effect between the additive and the active component, or on the structural regulation of the additive, and only through co-precipitation can it play its best role. However, as the research deepens, researchers have gradually found that the traditional co-precipitation method and the simple additive doping mode are difficult to improve the comprehensive performance of cobalt-based oxide catalysts, and cannot meet the harsh requirements of catalysts for the actual treatment of N2O pollution in industrial waste gas.

[0005] Sol-gel is a simple method for catalyst synthesis and is also commonly used to prepare N2O decomposition catalysts. However, the choice of complexing agent during preparation has a significant impact on the performance of the catalyst. When using citric acid as a complexing agent and urea as a combustion agent, Sm-doped Co3O4 catalysts were prepared, and the decomposition performance of N2O on the catalyst was significantly improved (Liu et al., Chemical Engineering Journal. 2021, 414, 128643). In addition, the research group used the sol-gel method to integrate Co3O4 catalysts containing single-atom Pr into their matrix (Liu et al., Environmental Science and Technology. 2022, 56, 16325-16335), which showed higher catalytic efficiency, and with the increase of the amount of the auxiliary agent, the reaction conversion rate changed in a volcanic type.

[0006] The previous invention patent CN115739090A of the research group provides a catalyst that can be used for N2O decomposition in industry and its preparation method. The method is based on the sol-gel method supplemented with non-ionic surfactant F127 (PEO 106 PPO 70 PEO 106 , Mav=12600), Co3O4 catalysts with special "sub-Dan landform" microstructure and exposed high activity (400) and (511) crystal faces can be successfully obtained. In the catalytic decomposition of N2O in simulated nitric acid plant tail gas, the catalyst showed better low-temperature activity and stability than Co3O4 obtained by conventional precipitation method. The results show that non-ionic surfactants have great potential in the synthesis of high-activity catalysts by sol-gel method.

[0007] Based on the previous research of the research group, in order to further reduce the preparation cost of the catalyst and improve the comprehensive performance of the catalyst, industrial surfactants Triton X-100, Tergitol NP-40 and OP-10 Emulsifier were selected as complexing agents, and the morphology and structure of the obtained catalysts were controlled by changing the preparation conditions. So far, there has been no report on the use of sol-gel method and the addition of the above commonly used industrial surfactants to synthesize catalysts for catalytic decomposition of N2O, and there has been no report on the tolerance of such catalysts to NO x , O2, H2O impurities in simulated real nitric acid plant environment. SUMMARY

[0008] In order to solve the problems that the catalytic activity of the cobalt-based catalyst is difficult to continue to improve the low-temperature catalytic activity and the resistance to impurity gas is poor, the application provides a preparation process of a transition metal oxide catalyst with good low-temperature activity, simple preparation process, good stability and good resistance to NO x , O2, H2O impurity gas, and application thereof. On the basis of the catalyst preparation process, more high-activity N2O catalysts can be prepared under different catalyst formulations.

[0009] The technical scheme of the application is: a preparation method of a transition metal oxide catalyst for efficiently catalytically decomposing N2O pollution, comprising the following steps: dissolving a proper amount of a specific surfactant into deionized water, adding a certain amount of inorganic acid, stirring until completely miscible, adding transition metal nitrate, reacting until gelatinous, drying to obtain dry gel, calcining, and obtaining the target catalyst.

[0010] The preparation method of the transition metal oxide catalyst for efficiently catalytically decomposing N2O pollution, the transition metal nitrate is one or more of Co(NO3)2·6H2O, Cu(NO3)2·3H2O and Ni(NO3)2·6H2O.

[0011] The preparation method of the transition metal oxide catalyst for efficiently catalytically decomposing N2O pollution, the surfactant is one or more of common industrial inexpensive surfactants Triton X-100 polyethylene glycol octylphenyl ether, molecular formula is C 18 H 28 O5, Tergitol NP-40 nonylphenol polyoxyethylene ether, molecular formula is C 33 H 60 O 10 , OP-10 Emulsifier octylphenol polyoxyethylene ether, molecular formula is C8H 17 C6H4(OCH2CH2) n OH.

[0012] The preparation method of the transition metal oxide catalyst for efficiently catalytically decomposing N2O pollution, the inorganic acid is HNO3.

[0013] The preparation method of the transition metal oxide catalyst for efficiently catalytically decomposing N2O pollution, the stirring temperature is 15℃-35℃.

[0014] The preparation method of the transition metal oxide catalyst for efficiently catalytically decomposing N2O pollution, the reaction temperature is 70℃-95℃, and the reaction time is 3h-30h.

[0015] The preparation method of the transition metal oxide catalyst for high-efficiency catalytic decomposition of N2O pollution, wherein the drying temperature is 100-150 DEG C; and the drying time is 12-24 hours.

[0016] The preparation method of the transition metal oxide catalyst for high-efficiency catalytic decomposition of N2O pollution, wherein the calcination is carried out at 140-160 DEG C for 0.5-1.5 hours, at 240-260 DEG C for 0.5-1.5 hours, and at 350-450 DEG C for 1-4 hours.

[0017] The application of the transition metal oxide catalyst prepared by the preparation method in catalytic decomposition of N2O.

[0018] The application of the transition metal oxide catalyst prepared by the preparation method in catalytic decomposition of N2O.

[0019] The application of the transition metal oxide catalyst prepared by the preparation method in catalytic decomposition of N2O.

[0020] The preparation method of the present application is an industrial non-ionic surfactant-assisted sol-gel method, and the obtained catalyst has a large number of oxygen vacancies and exposes a large number of different crystal surfaces, and it is just due to the high surface oxygen vacancy density and different crystal surface exposure of the crystal surface that a large number of active sites are provided for the catalytic decomposition of N2O.

[0021] The active component of the catalyst prepared by the present application is a transition metal oxide, which not only has excellent low-temperature direct catalytic decomposition activity of N2O, but also has extremely high low-temperature catalytic activity, and the catalytic conversion rate of the prepared catalyst 10TX-Co3O4 to N2O reaches 90% at 300 DEG C. x , O2, H2O and other impurities, and the catalyst can still maintain an N2O conversion rate of more than 80% for more than 15 hours under the condition of full impurity gas (5vol% O2+100ppmv NO+2vol% H2O) at 400 DEG C, and is suitable for application in actual industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is the activity diagram of the catalysts obtained in Examples 1-7 and Comparative Examples 1 and 2 in catalytic decomposition of N2O.

[0023] Figure 2 is the activity diagram of the catalysts obtained in Comparative Example 3 and Comparative Examples 1 and 2 in catalytic decomposition of N2O.

[0024] Figure 3 is the resistance test diagram of the catalyst obtained in Example 1 to impurity gas.

[0025] Figure 4 is a stability test graph of the catalyst obtained in Example 1 to impurity gas.

[0026] Figure 5 is a TEM graph of the catalyst sample obtained in Example 1, A is an electron microscope graph of S(1)-10TX-Co3O4 catalyst sample at 10,0000 times magnification, B, C are magnified graphs of two different areas in A, b1, b2 are partial magnified graphs of B, c1 is a partial magnified graph in C.

[0027] Figure 6 is an XPS analysis graph of the catalysts obtained in Example 1 and Comparative Examples 1, 2, wherein A is a Co 2p spectrum graph of B(1)-Co3O4(P), B(2)-0TX-Co3O4, S(1)-10TX-Co3O4, B is an O 1s orbital spectrum graph of B(1)-Co3O4(P), B(2)-0TX-Co3O4, S(1)-10TX-Co3O4. DETAILED DESCRIPTION

[0028] In order for those skilled in the art to have a more comprehensive understanding of the present application, the present application is described in more detail by the following non-limiting examples or comparative examples, but the examples or comparative examples do not limit the present application in any way.

[0029] Preparation of transition metal oxide catalyst S(1)-10TX-Co3O4 of Example 1

[0030] 10 g of surfactant Triton X-100 (a polyethylene glycol octylphenyl ether, molecular formula C 18 H 28 O5) was dissolved into a beaker containing 17 mL of deionized water and 2.4 g of HNO3, and after stirring to dissolution at room temperature, 5.0 g of Co(NO3)2·6H2O was added, and the reaction was stirred in a 90℃ water bath until a gel that was difficult to stir was formed, and then the obtained product was placed in an oven at 120℃ and dried for 12 h or more to obtain a dry gel, which was ground and placed in a muffle furnace and calcined at 400℃ at a temperature increasing rate of 5℃ / min for 2 h to obtain the catalyst S(1)-10TX-Co3O4 (xTX-Co3O4), wherein x represents the amount of surfactant, and TX represents the surfactant Triton X-100.

[0031] Preparation of catalyst S(2)-2TX-Co3O4 of Example 2

[0032] Prepared according to the method described in Example 1, except that 2 g of Triton X-100 was used instead of 10 g of Triton X-100 in Example 1 to obtain the catalyst S(2)-2TX-Co3O4.

[0033] Preparation of catalyst S(3)-4TX-Co3O4

[0034] Prepared according to the method described in example 1 except that 4 g of Triton X-100 was used instead of 10 g of Triton X-100 in example 1 to obtain catalyst S(3)-4TX-Co3O4.

[0035] Preparation of catalyst S(4)-6TX-Co3O4

[0036] Prepared according to the method described in example 1 except that 6 g of Triton X-100 was used instead of 10 g of Triton X-100 in example 1 to obtain catalyst S(4)-6TX-Co3O4.

[0037] Preparation of catalyst S(5)-8TX-Co3O4

[0038] Prepared according to the method described in example 1 except that 8 g of Triton X-100 was used instead of 10 g of Triton X-100 in example 1 to obtain catalyst S(5)-8TX-Co3O4.

[0039] Preparation of catalyst S(6)-9TX-Co3O4

[0040] Prepared according to the method described in example 1 except that 9 g of Triton X-100 was used instead of 10 g of Triton X-100 in example 1 to obtain catalyst S(6)-9TX-Co3O4.

[0041] Preparation of catalyst S(7)-1 1 TX-Co3O4

[0042] Prepared according to the method described in example 1 except that 1 1 g of Triton X-100 was used instead of 10 g of Triton X-100 in example 1 to obtain catalyst S(7)-1 1 TX-Co3O4.

[0043] Preparation of catalyst S(8)-1 OP-Co3O4

[0044] Prepared according to the method described in example 1 except that 1 g of OP-10 Emulsifier was used instead of 10 g of Triton X-100 in example 1 to obtain catalyst S(8)-1 OP-Co3O4.

[0045] Preparation of catalyst S(9)-3OP-Co3O4

[0046] Prepared according to the method described in Example 1 except that 3 g of OP-10 Emulsifier was used instead of 10 g of Triton X-100 in Example 1 to give catalyst S(9)-3OP-Co304.

[0047] Example 10 Preparation of catalyst S(10)-5OP-Co304

[0048] Prepared according to the method described in Example 1 except that 5 g of OP-10 Emulsifier was used instead of 10 g of Triton X-100 in Example 1 to give catalyst S(10)-5OP-Co304.

[0049] Example 11 Preparation of catalyst S(11)-7OP-Co304

[0050] Prepared according to the method described in Example 1 except that 7 g of OP-10 Emulsifier was used instead of 10 g of Triton X-100 in Example 1 to give catalyst S(11)-7OP-Co304.

[0051] Example 12 Preparation of catalyst S(12)-9OP-Co304

[0052] Prepared according to the method described in Example 1 except that 9 g of OP-10 Emulsifier was used instead of 10 g of Triton X-100 in Example 1 to give catalyst S(12)-9OP-Co304.

[0053] Example 13 Preparation of catalyst S(13)-11OP-Co304

[0054] Prepared according to the method described in Example 1 except that 11 g of OP-10 Emulsifier was used instead of 10 g of Triton X-100 in Example 1 to give catalyst S(13)-11OP-Co304.

[0055] Example 14 Preparation of catalyst S(14)-13OP-Co304

[0056] Prepared according to the method described in Example 1 except that 13 g of OP-10 Emulsifier was used instead of 10 g of Triton X-100 in Example 1 to give catalyst S(14)-13OP-Co304.

[0057] Example 15 Preparation of catalyst S(15)-14OP-Co304

[0058] Prepared according to the method described in Example 1, except that 14 g of OP-10 Emulsifier was used instead of 10 g of Triton X-100 in Example 1, to give catalyst S(15)-14OP-Co304.

[0059] Example 16 Preparation of catalyst S(16)-15OP-Co304

[0060] Prepared according to the method described in Example 1, except that 15 g of OP-10 Emulsifier was used instead of 10 g of Triton X-100 in Example 1, to give catalyst S(16)-15OP-Co304.

[0061] Example 17 Preparation of catalyst S(17)-17OP-Co304

[0062] Prepared according to the method described in Example 1, except that 17 g of OP-10 Emulsifier was used instead of 10 g of Triton X-100 in Example 1, to give catalyst S(17)-17OP-Co304.

[0063] Preparation of catalyst B(l)-Co304(P)

[0064] Cobalt nitrate hexahydrate (Co(N03)2-6H20) 5.8206 g was dissolved in 100 mL of deionized water to give a homogeneous precursor solution. Subsequently, under continuous stirring at 40 °C, a 0.5 mol-L -1 of Na2C03solution was added dropwise to pH 9.3, and allowed to age sufficiently to ensure complete precipitation. The precipitated suspension was thoroughly washed with deionized water to remove residual ions and impurities. The washed precipitate was dried at 110 °C, ground, and calcined in air at 500 °C for 3 hours to give catalyst B(l)-Co304(P).

[0065] Preparation of catalyst B(2)-0TX-Co304 / B(2)-0OP-Co304

[0066] Prepared according to the method described in Example 1, except that no surfactant was added during the preparation to give catalyst B(2)-0TX-Co304 / B(2)-0OP-Co304.

[0067] Preparation of catalyst B(3)-10TX-NiO

[0068] Prepared according to the method described in Example 1, except that 5 g of Ni(NO3)2-6H2O was used instead of 5 g of Co(NO3)2-6H2O in Example 1, to give Catalyst B(4)-10TX-NiO.

[0069] Preparation of Catalyst B(4)-10TX-CuO

[0070] Prepared according to the method described in Example 1, except that 5 g of Cu(NO3)2-3H2O was used instead of 5 g of Co(NO3)2-6H2O in Example 1, to give Catalyst B(5)-10TX-CuO.

[0071] Preparation of Catalyst B(5)-4NP-Co3O4

[0072] Prepared according to the method described in Example 1, except that 4 g of Tergitol NP-40 was used instead of 10 g of Triton X-100 in Example 1, to give Catalyst B(6)-4NP-Co3O4.

[0073] Performance test of catalysts

[0074] The catalyst samples of Examples 1-17 and Comparative Examples 1, 2 were pressed into tablets using a mold, sieved, and 200 mg of the 40-60 mesh catalyst sample was placed in a quartz tube reactor (inner diameter: 4 mm) on a tubular atmospheric pressure integral fixed bed reactor. Before the activity test, the catalyst was treated at 400 °C for 30 minutes with pure Ar (50 mL min -1 ) to remove impurities adsorbed on the surface of the catalyst. Subsequently, the reaction gas consisting of 2000 ppmv N2O / Ar (or some impurity gases 5 vol.% O2, 2 vol.% H2O or 100 ppmv NO) was introduced into the reactor for direct catalytic decomposition of N2O reaction test. The residual N2O concentration was detected in real time by a Varian CP-3800 gas chromatograph (inner diameter equipped with a stationary phase Porapak Q and a thermal conductivity detector, high-purity Ar as carrier gas) through a six-way valve.

[0075] The results of the activity test of the catalysts of Examples 1-7 and Comparative Examples 1, 2 are shown in Table 1. Figure 1As shown in the figure, the catalytic activity of the catalyst samples (Examples 1-7) greatly improved after the addition of surfactant Triton X-100, all showing more excellent performance than Co3O4(P) (Comparative Example 1), while the catalyst 0TX-Co3O4 (Comparative Example 2) obtained without the addition of Triton X-100 during preparation had very poor activity. This shows that Triton X-100 plays a crucial role in improving catalytic performance, rather than the preparation method. As can be seen from the activity graph, the catalytic activity continuously rises with the increase of the amount of Triton X-100, and reaches the maximum activity when the amount of Triton X-100 is 10.0 g, at which the proportion of N2O converted into N2 and O2 is about 90% at 300°C. After reaching this value, further increase of the amount of Triton X-100 does not lead to improvement of the performance of the catalyst. This means that with the assistance of Triton X-100, a high-activity Co3O4 catalyst for catalytic decomposition of N2O can be obtained by the sol-gel method, which opens up a new way for the synthesis of high-activity cobalt-based catalysts in the future.

[0076] The results of the catalyst activity test of Examples 8-17 and Comparative Examples 1 and 2 are shown in the figure Figure 2 As shown in the figure, the catalytic activity of the catalyst samples (Examples 8-17) greatly improved after the addition of surfactant OP-10 Emulsifier, and reached nearly 100% N2O conversion rate at 250°C when the optimal amount of 14 g was added, while the decomposition ability of the Co3O4 catalyst prepared by the precipitation method (Comparative Example 1) for N2O was almost 0 at the same temperature. In addition, it can also be seen that when no surfactant OP-10 Emulsifier is added, the catalytic performance of catalyst B(2) is the worst, even lower than that of catalyst sample B(1) prepared by the ordinary coprecipitation method, which proves that the surfactant is the key to the activity improvement.

[0077] The impurity gas resistance of the catalyst with the best activity (the catalyst obtained in Example 1) was tested

[0078] In order to determine the resistance of the catalyst S(1)-10TX-Co3O4 with the best activity to impurity gases (NO x , O2, H2O), the ability of the catalyst to catalytically decompose N2O in the presence of different impurity gases at different temperatures was determined, and the related results are shown in the figure Figure 3 As shown in the figure, when no impurity gas was introduced into the system, the T 90The temperature at which the N2O conversion rate reached 90% was 300°C; when 100 ppmv NO, 5 vol.% O2 and 2 vol.% H2O were added to the reaction system respectively, the activity of the catalysts all decreased to different degrees, which means that NO, O2 and H2O all inhibited the activity of the catalysts, but the inhibition was relatively limited. In addition, when all the impurity gases (100 ppmv NO, 5 vol.% O2 and 2 vol.% H2O) were introduced into the reaction system, the N2O conversion rate of the catalyst S(l)-lOTX-Co3O4 could still reach 100% at 400°C.

[0079] Stability test of the most active catalyst (catalyst obtained in Example 1)

[0080] In order to determine the stability of the most active catalyst S(l)-lOTX-Co3O4 after long-term introduction of impurity gases, a stability test of the catalyst was carried out for 26 h, and the results are shown in Figure 4 First, the catalyst was continuously exposed to the environment of N2O at 400°C, and it was found that the conversion rate of the catalyst remained at 100%; then all the impurity gases (100 ppmv NO, 5 vol.% O2 and 2 vol.% H2O) were directly introduced, and the activity of the catalyst rapidly decreased and finally remained at about 81%; then the temperature was lowered, and it was found that the conversion rate of the catalyst remained at about 13% when all the impurity gases were introduced at 350°C. After that, all the impurity gases were cut off, and the N2O conversion rate of the catalyst gradually increased to 100% and remained stable.

[0081] TEM image analysis of the most active catalyst (catalyst obtained in Example 1)

[0082] In order to further explore the changes in the morphology of the catalyst, the microstructure morphology and crystal face exposure of the S(l)-lOTX-Co3O4 catalyst were analyzed in more detail by transmission electron microscopy (TEM), and the results are shown in Figure 5 Figure A is an electron microscope image of the S(l)-lOTX-Co3O4 catalyst sample at a magnification of 10,0000 times, and it can be seen that the Co3O4 grains in the catalyst exhibit irregular spherical morphology and have pore structures. Different regions (B and C) in Figure A were further enlarged, as shown in Figures bl, b2, cl. From the enlarged high-resolution TEM photos, it can be seen that the S(l)-lOTX-Co3O4 catalyst mainly exposes (111) and (400) crystal faces, which is completely different from the pure Co3O4 catalyst prepared by the traditional precipitation method (mainly exposing (222) and (311) crystal faces). That is, the addition of Triton X-100 makes the catalyst expose more crystal faces, and the preferential exposure of different crystal faces is probably an important reason for the excellent catalytic performance of the catalyst.

[0083] XPS analysis of the active catalyst (catalyst from Example 1)

[0084] To explore the changes of surface chemical properties of the catalysts, the surface properties of the B(l)-Co3O4(P) from Comparative Example 1, B(2)-0TX-Co3O4 from Comparative Example 2 and S(l)-10TX-Co3O4 from Example 1 were analyzed by XPS photoelectron spectroscopy, as shown in Figure 6 Figure 6 A is the Co 2p spectrum of the three catalyst samples. The two obvious characteristic peaks of the three catalysts are attributed to the Co 2p1 / 2and Co 2p3 / 2orbit of spinel Co3O4. The shift of Co 2p3 / 2spin-orbit to low binding energy proves that the Co-O bond in the Co3O4 catalyst is weakened. Accordingly, it can be seen that the value of Co 2p3 / 2orbit of the sample with Triton X-100 is shifted to 779.6 eV, and the proportion of Co 3+ increases to 52.2%, indicating that the addition of Triton X-100 in the synthesis process changes the surface properties of the Co3O4 catalyst. In addition, the O1s orbit of the three catalysts was also deconvoluted, as shown in Figure 6 B, the O 1s orbit spectrum contains three deconvoluted peaks, which are attributed to the surface lattice oxygen (O β ), surface adsorbed oxygen (O α1 ), oxygen from water or hydroxyl species (O α2 ). By calculating the area of each, the proportion of different atoms was obtained, and the proportion of surface adsorbed oxygen of the S(l)-10TX-Co3O4 sample was 55.9%. After the incorporation of Triton X-100, the number of surface adsorbed oxygen increased, which is consistent with the conclusion that the S(l)-10TX-Co3O4 catalyst contains more Co 3+ ​​

Claims

1. A method for preparing a highly efficient transition metal oxide catalyst for the catalytic decomposition of N₂O, characterized in that, The process includes the following steps: dissolving an appropriate amount of a specific surfactant in deionized water, adding a certain amount of inorganic acid, stirring until completely miscible, adding Co(NO3)2·6H2O, reacting at 70℃~95℃ for 3h~30h until a gel is formed, drying to obtain a dry gel, calcining to obtain the target catalyst; the surfactant is Triton X-100 polyethylene glycol octylphenyl ether or OP-10 Emulsifier octylphenol polyoxyethylene ether, with the molecular formula C8H 17 C6H4(OCH2CH2) n OH.

2. The method for preparing a highly efficient transition metal oxide catalyst for the catalytic decomposition of N₂O according to claim 1, characterized in that, The inorganic acid is HNO3.

3. The method for preparing a highly efficient transition metal oxide catalyst for the catalytic decomposition of N₂O according to claim 1, characterized in that, The stirring temperature is 15℃~35℃.

4. The method for preparing a highly efficient transition metal oxide catalyst for the catalytic decomposition of N₂O according to claim 1, characterized in that, The drying temperature is 100℃~150℃; the drying time is 12h~24h.

5. The method for preparing a highly efficient transition metal oxide catalyst for the catalytic decomposition of N₂O according to claim 1, characterized in that, The calcination is carried out at 140℃~160℃ for 0.5h~1.5h, at 240℃~260℃ for 0.5h~1.5h, and at 350℃~450℃ for 1h~4h.

6. The application of the transition metal oxide catalyst prepared by the method according to claim 1 in the catalytic decomposition of N2O.

7. The application according to claim 6, characterized in that, The method is as follows: The transition metal oxide catalyst prepared according to the preparation method of claim 1 is placed in a reactor, and N2O is introduced to carry out catalytic decomposition.

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