Method for synthesizing interfacial catalyst containing controllable quantity of CeO2 / Co3O4 through turbid liquid electrostatic spinning

Abstract

The invention discloses a method for synthesizing an interfacial catalyst containing controllable amount of CeO2 / Co3O4 through turbid liquid electrostatic spinning. The preparation method is characterized by comprising the following steps: adding sodium acetate and cobalt nitrate into an aqueous solution containing silicon dioxide, carrying out ultrasonic treatment, stirring, hydrothermal treatment and centrifugal drying to prepare spinel type Co-SiO2, then adding a mixed solution containing cerium nitrate, N-N-dimethylformamide and polyvinylpyrrolidone, spinning under the voltage of 27kV and at the liquid inlet speed of 0.5 mL / hde to obtain fibers, and finally calcining to obtain the catalyst. Results show that a series of catalysts containing different CeO2 / Co3O4 interfaces can be prepared by adjusting the content of cerous nitrate in a polymer solution; the CeO2 / Co3O4 interface affects the oxidation-reduction performance of the catalyst and the release ability of surface active oxygen species. According to the method, the number of interfaces in the catalyst is changed through the addition amount of cerium nitrate which is easy to regulate and control, the result is controllable, and the catalyst has better water resistance and stability.

Description

Technical Field

[0001] The invention relates to a preparation method for constructing a controllable amount of composite metal oxide interface, in particular to a preparation method for preparing composite metal oxide fibers containing a controllable amount of CeO2 / Co3O4 by electrospinning a suspension with high catalytic activity. Background Art

[0002] Spinel transition metal oxides have been extensively studied in the past decade due to their abundant reserves. Numerous studies have shown that the strength of metal-oxygen bonds can be tuned by increasing the surface lattice oxygen (O latt ) to improve the catalytic performance, and the surface lattice oxygen is crucial for the degradation of volatile organic compounds based on the Mars-van Krevelen (MvK) mechanism. latt It has become an attractive alternative catalyst for VOC oxidation due to its low barrier to VOC reactions and excellent redox capabilities. 3+ and Ce 4+ Oxidized CeO2 shows reversible surface oxygen ion exchange, high oxygen storage capacity, and good electronic / ionic conductivity, which provides opportunities for strong electronic coupling with other materials. Due to the close interaction between different components, the construction of nanointerfaces can accelerate charge transfer and generate more oxygen vacancies. Gaseous oxygen has a great influence on the consumed O latt The rapid replenishment of can accelerate the deep oxidation of intermediates and achieve continuous elimination of VOCs. At the same time, the interface of metal oxides has a profound effect on the activity, stability and selectivity of metal oxides. Generally, they can be synthesized by methods such as impregnation, coprecipitation, cation exchange and surfactant induction. However, these methods cannot control the number of interfaces, and the macroscopic uneven distribution may hinder the selective use of catalysts. Taking advantage of the electrospinning technology to prepare homogeneous materials with diameters ranging from submicron to nanometer, the amount of CeO2 / Co3O4 composite metal oxide fibers can be controlled. Summary of the invention

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

[0004] To achieve the purpose of the present invention, the technical solution specifically comprises the following steps:

[0005] A method for synthesizing a suspension electrospinning catalyst containing a controllable amount of CeO2 / Co3O4 interface, characterized in that it specifically comprises the following steps:

[0006] S1) Synthesis of Co-SiO2

[0007] 1) Weigh SiO2, add pure water and perform ultrasonic treatment to obtain a silicon dioxide aqueous solution;

[0008] 2) Co(NO3)2·6H2O and CH3COONa were weighed, and pure water was added into a beaker and stirred, and the silica aqueous solution obtained in step 1) was poured into the mixture to obtain solution A;

[0009] 3) placing the solution A obtained in step 2) in an oven for hydroheating, then centrifuging the obtained mixture to remove impurities to obtain solid particles, and drying them in an oven to obtain Co-SiO2;

[0010] S2) Suspension electrospinning

[0011] 4) Weigh polyvinyl pyrrolidone, add NN-dimethylamide and stir to obtain a polymer solution;

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

[0013] 6) adding the Co-SiO2 obtained in step 3) to the solution B obtained in step 5) and mixing them evenly to obtain solution C;

[0014] The solution C obtained in step 6) is transferred into a syringe, and then electrospinning is performed, and the obtained membrane cloth is calcined to obtain the final catalyst 1Co@Si-nCe, wherein 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) described in step S1) is (0.09-0.2):(0.2-0.8):(2-8).

[0016] The Co(NO3)2·6H2O and CH3COONa described in step S1) are stirred with deionized water for 30 to 60 minutes, and then mixed with the silica aqueous solution and ultrasonicated for 30 to 60 minutes.

[0017] The solution in step S1) is heated in an oven at a temperature of 150 to 200° C. for 6 to 18 hours, and the mixture is centrifuged for 3 to 10 times to remove impurities.

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

[0019] Step S2) The stirring time of polyvinyl pyrrolidone and NN-dimethylamide is 4 to 8 hours, the stirring time of Ce(NO3)3·6H2O and the solution is 1 to 3 hours, and the ultrasonic mixing time of Co3O4-SiO2 and the solution is 1 to 3 hours.

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

[0021] Compared with the background technology, the technical solution of 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 components in the fiber.

[0024] (3) The present invention proposes for the first time a method for preparing composite metal oxide fibers containing a controllable amount of CeO2 / Co3O4 by electrospinning a suspension having high catalytic activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the XRD spectrum of the sample prepared in Example 1.

[0026] Figure 2 The sample 1Co-Si@9Ce prepared in Example 1 and the comparative examples 1-2 were heated to 200 ppm C8H8 / Air and the air velocity was 120000 mL h -1 g -1 Catalytic oxidation degradation curve of styrene under test conditions.

[0027] Figure 3 The 1Co@Si-9Ce sample prepared in Example 1 was heated to 200 ppm C8H8 / Air at a space velocity of 120000 mL h - 1 g -1 , and stability performance diagrams under different moisture content test conditions. DETAILED DESCRIPTION

[0028] The present invention is further described below in conjunction with embodiments, but the scope of protection claimed by the present invention is not limited to the scope represented by the embodiments.

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

[0030] S1) Synthesis of Co-SiO2

[0031] 1) Weigh 0.020 g of SiO2, add 10 mL of pure water and perform ultrasonication to obtain a silica aqueous solution;

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

[0033] 3) placing the solution obtained in step 2) in an oven for hydroheating, then centrifuging the obtained mixture to remove impurities to obtain solid particles, and drying them in an oven to obtain Co-SiO2;

[0034] S2) Suspension electrospinning

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

[0036] 5) Under stirring, 0.2-1.2 mmol Ce(NO3)3·6H2O was added to the polymer solution, and then 50 mg Co-SiO2 prepared in step S1) was added and ultrasonicated for 2 h. The obtained membrane was transferred into a syringe for electrospinning. The obtained membrane was taken out 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, wherein n is 5, 7, 9, 11 (see Figure 1 ).

[0037] Comparative Example 1 (without introduction of cerium nitrate)

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

[0039] Figure 1This is the catalytic oxidation degradation curve of styrene for the sample prepared in Example 1. It can be seen from the figure that the catalytic activity of the catalyst after constructing CeO2 / Co3O4 by electrospinning is improved compared with Co-SiO2, among which the performance of 1Co-Si@9Ce catalyst with an addition amount of cerium nitrate of 0.8 mmol is the best, which indicates that CeO2 / Co3O4 constructed by suspension electrospinning can effectively enhance the catalytic activity of the catalyst, and the catalytic activity can be affected by adjusting the number of CeO2 / Co3O4 interfaces by changing the addition amount of cerium nitrate.

[0040] Comparative Example 2 (random blending of cobalt cerium oxide)

[0041] The atomic ratio of cobalt and cerium consistent with the best 1Co@Si-9Ce catalyst in Example 1 was used. 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 polyvinyl pyrrolidone, add 20mL of NN-dimethylamide and stir for 12h, weigh 0.089mmol Co(NO3)2·6H2O and 0.8mmol Ce(NO3)2·6H2O and stir for 30min (2) The solution was transferred into a syringe for electrostatic spinning, and the obtained membrane cloth was taken out and placed in a muffle furnace and calcined at 550℃ for 4h at a heating rate of 5℃ / min to obtain a 1Co3O4 / 3CeO2 sample.

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

[0043] Obtained through styrene catalytic oxidation performance test Figure 2 The performance test curve of the samples shows that the 1Co-Si@9Ce catalyst exhibits the best C8H8 catalytic oxidation performance (T 50 =275℃, T 90 =310℃). By comparing Co-SiO2, it was found that the catalytic performance of the Co3O4 / CeO2 interface prepared by suspension electrospinning was significantly improved. In addition, by comparing and analyzing 1Co@Si-9Ce and 1Co3O4 / 3CeO2, it was found that the catalytic oxidation performance of the 1Co@Si-9Ce sample was better, which shows that the construction of the interface of the two metal oxides Co3O4 and CeO2 directly through electrospinning will lead to random combination of the crystal planes of the two metal oxides, which is not conducive to the improvement of the catalytic performance of styrene.

[0044] Figure 3 This is the cycle performance test diagram of 1Co@Si-9Ce catalytic oxidation of styrene. Figure 3 It can be observed that after 48 hours of water resistance test, the performance of the 1Co@Si-9Ce catalyst has hardly changed much, 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 according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for synthesizing a CeO2 / Co3O4 interfacial catalyst containing a controllable amount by electrospinning a suspension, characterized in that: The specific steps include: s1) Synthesis of Co-SiO2 1) Weigh SiO2, add pure water and perform ultrasonic treatment to obtain a silica aqueous solution; 2) Weigh Co(NO3)2·6H2O and CH3COONa, add pure water into a beaker and stir, then pour the silica aqueous solution obtained in step 1) into the mixture to obtain solution A; 3) placing the solution A obtained in step 2) in an oven for hydroheating, then centrifuging the obtained mixture to remove impurities to obtain solid particles, and drying them in an oven to obtain Co-SiO2; s2) Suspension electrospinning 4) Weigh polyvinyl pyrrolidone, add NN-dimethylamide and stir to obtain a polymer solution; 5) Weigh Ce(NO3)3·6H2O, add the polymer solution obtained in step 4) and stir to obtain solution B; 6) Add the Co-SiO2 obtained in step 3) to the solution B obtained in step 5) and mix well to obtain solution C; 7) The solution C obtained in step 6) is transferred into a syringe, and then electrospun, and the obtained membrane cloth is calcined to obtain the final catalyst 1Co@Si- n Ce, where n=5, 7, 9, 11.

2. The method for synthesizing a suspension electrospinning containing a controllable amount of CeO2 / Co3O4 interfacial catalyst according to claim 1, characterized in that: The ratio of SiO2 mass g, CH3COONa mass g, and Co(NO3)2·6H2O molar mass mmol described in step S1) is (0.05-0.2): (0.2-0.8): (2-8).

3. The method for synthesizing a suspension electrospinning containing a controllable amount of CeO2 / Co3O4 interfacial catalyst according to claim 1, characterized in that: The Co(NO3)2·6H2O and CH3COONa described in step S1) are stirred with deionized water for 30 to 60 minutes, and then mixed with the silica aqueous solution and ultrasonicated for 30 to 60 minutes.

4. The method for synthesizing a suspension electrospinning containing a controllable amount of CeO2 / Co3O4 interfacial catalyst according to claim 1, characterized in that: The solution in step S1) is heated in an oven at a temperature of 150 to 200°C for 6 to 18 hours, and the mixture is centrifuged for 3 to 10 times to remove impurities.

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

09.

6. The method for synthesizing a suspension electrospinning containing a controllable amount of CeO2 / Co3O4 interfacial catalyst according to claim 1, characterized in that: Step S2) The stirring time of polyvinyl pyrrolidone and NN-dimethylamide is 4 to 8 h, the stirring time of Ce(NO3)3·6H2O added to solution B is 1 to 3 h, and the mixing time of Co-SiO2 added to solution C and ultrasonically mixed is 1 to 3 h.

7. The method for synthesizing a suspension electrospinning containing a controllable amount of CeO2 / Co3O4 interfacial catalyst according to claim 1, characterized in that: The electrospinning conditions in step S2) are 22-30 kV voltage, 0.2-1.0 mL / h liquid feeding rate, and calcination conditions: heating rate of 2-8 o C / min; constant temperature is 400~600 o C; constant temperature calcination time 4 to 6 hours.

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