A method for synthesizing a CeO2 / Co3O4 interfacial catalyst by electrospinning of a suspension

Abstract

This invention discloses a method for synthesizing a catalyst containing a controllable amount of CeO2 / Co3O4 interface through electrospinning of a suspension. The method involves adding sodium acetate and cobalt nitrate to an aqueous solution containing silica, followed by ultrasonication, stirring, hydrothermal treatment, and centrifugal drying to prepare spinel-type Co-SiO2. Then, a mixed solution containing cerium nitrate, N-N-dimethylamide, and polyvinylpyrrolidone is added, and the mixture is spun into fibers at a voltage of 27 kV and a feed rate of 0.5 mL / hde. Finally, the catalyst is obtained by calcination. Results show that a series of catalysts with different CeO2 / Co3O4 interfaces can be prepared by adjusting the cerium nitrate content in the polymer solution. The CeO2 / Co3O4 interface affects the redox performance of the catalyst and the release capacity of surface active oxygen species. This method allows for controllable modification of the interface number in the catalyst through easily adjustable cerium nitrate addition, resulting in a catalyst with good water resistance and stability.

Description

Technical Field

[0001] This invention relates to a method for constructing a controllable amount of composite metal oxide interface, and more particularly to a method for preparing fibers containing a controllable amount of CeO2 / Co3O4 composite metal oxide by electrospinning a suspension with high catalytic activity. Background Technology

[0002] Spinel transition metal oxides are abundant and have therefore been extensively studied over the past decade. Numerous studies have shown that modulating metal-oxygen bond strength can be achieved by increasing the surface lattice oxygen (O₂). latt The reactivity of Co3O4 can enhance catalytic performance, while surface lattice oxygen is crucial for the degradation of volatile organic compounds based on the Mars-van Krevelen (MvK) mechanism. This is because Co3O4 reacts with O... latt With low barriers to VOC reactions and excellent redox capabilities, it has become a highly attractive alternative catalyst for VOC oxidation. It possesses Ce... 3+ and Ce 4+ Oxidized CeO2 exhibits reversible surface oxygen ion exchange, high oxygen storage capacity, and good electronic / ionic conductivity, providing opportunities for strong electronic coupling with other materials. Due to the close interactions between different components, the construction of nano-interfaces can accelerate charge transfer and generate more oxygen vacancies. Gaseous oxygen absorbs the consumed O2. latt Rapid replenishment can accelerate the deep oxidation of intermediate products, achieving continuous elimination of VOCs. Meanwhile, the interface of metal oxides has a profound impact on their activity, stability, and selectivity. Typically, they can be synthesized through methods such as impregnation, co-precipitation, cation exchange, and surfactant induction. However, these methods cannot control the number of interfaces, and macroscopically uneven distribution may hinder the selective use of catalysts. Utilizing the advantages of electrospinning technology in preparing homogeneous materials with diameters ranging from submicron to nanometer, the number of CeO2 / Co3O4 composite metal oxide fibers can be controlled. Summary of the Invention

[0003] Based on the above problems, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for synthesizing a CeO2 / Co3O4 interfacial catalyst containing a controllable amount by electrospinning of a suspension. This method can effectively construct a composite metal oxide interface, is highly operable, and meets environmental requirements.

[0004] To achieve the objectives of this invention, the technical solution specifically includes the following steps:

[0005] A method for synthesizing a CeO2 / Co3O4 interfacial catalyst containing a controllable amount by electrospinning of a suspension, characterized by comprising the following steps:

[0006] Synthesis of S1)Co-SiO2

[0007] 1) Weigh SiO2, add pure water and sonicate to obtain an aqueous solution of silicon dioxide;

[0008] 2) Weigh out Co(NO3)2·6H2O and CH3COONa, add pure water to a beaker and stir, then pour in the silica aqueous solution obtained in step 1) and mix to obtain solution A;

[0009] 3) Place the solution A obtained in step 2) in an oven for hydrothermal treatment, then centrifuge the resulting mixture to remove impurities and obtain solid particles, which are then dried in an oven to obtain Co-SiO2;

[0010] S2) Electrospinning of suspension

[0011] 4) Weigh out polyvinylpyrrolidone, add N,N-dimethylamide and stir to obtain a polymer solution;

[0012] 5) Weigh Ce(NO3)3·6H2O, add it to the polymer solution obtained in step 4) and stir to obtain solution B;

[0013] 6) Add the Co-SiO2 obtained in step 3) to solution B obtained in step 5) and mix well to obtain solution C;

[0014] The solution C obtained in step 6) is transferred into a syringe and then electrospun. The resulting membrane is calcined to obtain the final catalyst 1Co@Si-nCe, where n=5,7,9,11.

[0015] The ratio of the mass of SiO2 (g), the mass of CH3COONa (g), and the molar mass of Co(NO3)2·6H2O (mmol) in step S1) is (0.09~0.2):(0.2~0.8):(2~8).

[0016] In step S1), the Co(NO3)2·6H2O and CH3COONa are stirred with deionized water for 30-60 min, and then mixed with an aqueous silica solution and sonicated for 30-60 min.

[0017] In step S1), the hydrothermal temperature in the solution drying oven is 150-200℃ for 6-18 hours, and the mixture is centrifuged 3-10 times to remove impurities.

[0018] The mass ratio of polyvinylpyrrolidone (g), N-dimethylamide (mL), Ce(NO3)3·6H2O (mmol), and Co-SiO2 (g) in step S2) is (1-5):(10-30):(0.05-2):(0.01-0.09).

[0019] Step S2) The stirring time of polyvinylpyrrolidone and NN-dimethylamide is 4-8h, the stirring time of Ce(NO3)3·6H2O with the solution is 1-3h, and the ultrasonication time of Co3O4-SiO2 mixed with the solution is 1-3h.

[0020] The electrospinning conditions described in step S2) are a voltage of 22-30 kV and a liquid feed rate of 0.2-1.0 mL / h. The calcination conditions are: a heating rate of 2-8 °C / min; a constant temperature of 400-600 °C; and a constant temperature calcination time of 4-6 h.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] (1) The present invention can control the number of interfaces in the catalyst by simply adjusting the amount of cerium nitrate added.

[0023] (2) The present invention utilizes electrospinning technology to generate a catalyst with stable morphology and uniform distribution of each component in the fiber.

[0024] (3) This invention proposes for the first time a method for preparing fibers containing controllable amounts of CeO2 / Co3O4 composite metal oxides by electrospinning a suspension with high catalytic activity. Attached Figure Description

[0025] Figure 1 The image shows the XRD pattern of the sample prepared in Example 1.

[0026] Figure 2 Sample 1 (Co-Si@9Ce) prepared in Example 1 and Comparative Examples 1-2 were subjected to a C8H8 / Air mixture at 200 ppm and a space velocity of 120,000 mL / h. -1 g -1 The catalytic oxidative degradation curve of styrene under the test conditions.

[0027] Figure 3 The 1Co@Si-9Ce sample prepared in Example 1 was subjected to a space velocity of 1200 mL / h at 200 ppm C8H8 / Air. - 1 g -1 And stability performance diagrams under different moisture content test conditions. Detailed Implementation

[0028] The present invention will be further described below with reference to the embodiments, but the scope of protection of the present invention is not limited to the scope shown in the embodiments.

[0029] Example 1 (Cerium nitrate with different contents)

[0030] Synthesis of S1)Co-SiO2

[0031] 1) Weigh 0.020 g of SiO2, add 10 mL of pure water and sonicate to obtain an aqueous solution of silicon dioxide;

[0032] 2) Weigh 1 mmol and 0.90 g of Co(NO3)2·6H2O and CH3COONa respectively, add 10 mL of pure water to a beaker and stir, then pour in the silica aqueous solution obtained in step 1) and mix to obtain a solution;

[0033] 3) Place the solution obtained in step 2) in an oven for hydrothermal treatment, then centrifuge the resulting mixture to remove impurities and obtain solid particles, which are then dried in an oven to obtain Co-SiO2;

[0034] S2) Electrospinning of suspension

[0035] 4) Polymer solution: Weigh 2g of polyvinylpyrrolidone and add 20mL of NN-dimethylamide and stir for 12h.

[0036] 5) Under stirring conditions, 0.2–1.2 mmol of Ce(NO3)3·6H2O was added to the polymer solution, followed by 50 mg of Co-SiO2 prepared in step S1) and ultrasonication for 2 h. The solution was then transferred to a syringe for electrospinning. The resulting membrane was removed and placed in a muffle furnace and calcined at 550 °C for 4 h at a heating rate of 5 °C / min to obtain 1Co@Si-nCe samples, where n was 5, 7, 9, or 11 (see...). Figure 1 ).

[0037] Comparative Example 1 (without cerium nitrate)

[0038] 50 mg of Co-SiO2 tablets prepared in step S1 of Example 1 were weighed directly and compressed into tablets. The activity was tested under 200 ppm C8H8 / Air conditions.

[0039] Figure 1The figure shows the catalytic oxidation degradation curves of styrene for the sample prepared in Example 1. As can be seen from the figure, the catalytic activity of the catalyst constructed by electrospinning CeO2 / Co3O4 was improved compared with Co-SiO2. Among them, the 1Co-Si@9Ce catalyst with an addition of 0.8 mmol of cerium nitrate had the best performance. This indicates that CeO2 / Co3O4 constructed by electrospinning suspension can effectively enhance the catalytic activity of the catalyst, and the catalytic activity can be affected by adjusting the amount of cerium nitrate added to control the number of CeO2 / Co3O4 interfaces.

[0040] Comparative Example 2 (Disordered blending of cobalt and cerium oxides)

[0041] The atomic ratio of cobalt to cerium was the same as that of the optimal 1Co@Si-9Ce catalyst in Example 1. The difference in the synthesis process was that the cobalt source was added by adding a certain amount of cobalt nitrate to the solution in an electrostatic manner. The specific steps are as follows: (1) Weigh 2g of polyvinylpyrrolidone, add 20mL of NN-dimethylamide and stir for 12h. Weigh 0.089mmol of Co(NO3)2·6H2O and 0.8mmol of Ce(NO3)2·6H2O and stir for 30min. (2) Transfer the solution into a syringe for electrospinning. Take out the obtained membrane and place it in a muffle furnace and calcine it at 550℃ for 4h at a heating rate of 5℃ / min to obtain the 1Co3O4 / 3CeO2 sample.

[0042] Figure 1 The XRD pattern of the catalyst prepared in Example 1 shows that the diffraction peaks of all catalysts are consistent with the standard cards of Co3O4 (PDF, 96-900-5889) and CeO2 (PDF, 81-0792), indicating that suspension electrospinning can successfully introduce Co-SiO2 nanoparticles into electrospun fibers.

[0043] Obtained through styrene catalytic oxidation performance testing Figure 2 The performance test curves of the samples show that the 1Co-Si@9Ce catalyst exhibits the best C8H8 catalytic oxidation performance among all catalysts (T). 50 =275℃, T 90 =310℃). Comparison with Co-SiO2 revealed that the catalyst performance of the Co3O4 / CeO2 interface prepared by suspension electrospinning was significantly improved. Furthermore, comparative analysis of 1Co@Si-9Ce and 1Co3O4 / 3CeO2 showed that the 1Co@Si-9Ce sample exhibited better catalytic oxidation performance. This indicates that directly constructing the interface between the two metal oxides, Co3O4 and CeO2, via electrospinning leads to random crystal facet combinations of the two oxides, which is not conducive to improving the catalytic performance of styrene.

[0044] Figure 3 The graph shows the cyclic performance test results of 1Co@Si-9Ce for the catalytic oxidation of styrene. Figure 3 It can be observed that after 48 hours of water resistance testing, the performance of the 1Co@Si-9Ce catalyst hardly changed, indicating that the catalyst has good stability.

[0045] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for electrospinning synthesis of a suspension containing a controllable amount of CeO2 / Co3O4 interface catalyst, characterized in that, Specifically comprising the following steps: S1) synthesis of Co-SiO2 1) SiO2 was weighed, pure water was added and ultrasonic was performed to obtain a silica aqueous solution; 2) Co(NO3)2·6H2O and CH3COONa were weighed, and pure water was added in a beaker and stirred, and then poured into the silica aqueous solution obtained in step 1) to obtain solution A; 3) solution A obtained in step 2) was placed in an oven for hydrothermal treatment, and then the obtained mixture was centrifuged to remove impurities to obtain solid particles, and dried in an oven to obtain Co-SiO2; S2) suspension electrospinning 4) polyvinylpyrrolidone was weighed, N,N-dimethylamide was added and stirred to obtain a polymer solution; 5) Ce(NO3)3·6H2O was weighed, added to the polymer solution obtained in step 4) and stirred to obtain solution B; 6) Co-SiO2 obtained in step 3) was added to solution B obtained in step 5) and mixed uniformly to obtain solution C; 7) solution C obtained in step 6) was transferred into a syringe, and then electrospinning was performed, and the obtained film cloth was calcined to obtain the final catalyst 1Co@Si-nCe, wherein n = 5, 7, 9, 11.

2. The method of claim 1, wherein the suspension electrospinning synthesis of Ce02 / Co304 interfacial catalyst with controllable amount is characterized in that: In step S1), the mass of SiO2 g, the mass of CH3COONa g, and the amount of Co(NO3)2·6H2O mmol are in the ratio of (0.05-0.2):(0.2-0.8):(2-8).

3. The method of claim 1, wherein the suspension electrospinning synthesis of Ce02 / Co304 interfacial catalysts with controllable amounts comprises: In step S1), the stirring time of Co(NO3)2·6H2O and CH3COONa with deionized water is 30-60 min, and then mixed with the silica aqueous solution and ultrasonic is performed for 30-60 min.

4. The method of claim 1, wherein the suspension electrospinning synthesis of Ce02 / Co304 interfacial catalysts with controllable amounts comprises: In step S1), the temperature of solution A in the oven for hydrothermal treatment is 150-200 ℃, and the time is 6-18 h, and the obtained mixture is centrifuged 3-10 times to remove impurities.

5. The method for synthesizing a CeO2 / Co3O4 interfacial catalyst by electrospinning of a suspension according to claim 1, characterized in that: In step S2), the mass of polyvinylpyrrolidone g, the volume of N,N-dimethylamide mL, the amount of Ce(NO3)3·6H2O mmol, and the mass of Co-SiO2 g are in the ratio of 1-5:10-30:0.05-2:0.01-0.

09.

6. The method of claim 1, wherein the suspension electrospinning synthesis of Ce02 / Co304 interfacial catalysts with controllable amounts comprises: In step S2), the stirring time of polyvinylpyrrolidone with N-N-dimethylamide is 4-8 h, the stirring time of Ce(NO3)3·6H2O added to solution B is 1-3 h, and the ultrasonic mixing time of Co-SiO2 added to solution C is 1-3 h.

7. The method of claim 1, wherein the method of electrospinning of the suspension for synthesis of the CeO2 / Co3O4 interfacial catalyst with a controllable amount is characterized by: Step S2) the electrospinning conditions are 22-30 kV voltage, 0.2-1.0 mL h -1 of liquid feeding speed, and the calcination conditions are: the temperature increasing rate is 2-8 ℃ min -1 ; the constant temperature is 400-600 ℃; and the constant temperature calcination time is 4-6 h.

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