Preparation method and application of Pt NPs / Fe2O3 hexagon catalyst

Abstract

The invention discloses a preparation method and application of a Pt NPs / Fe2O3hexagon catalyst, comprising the following steps: (1) ultrasonically dissolving ferric chloride hexahydrate in anhydrous ethanol to obtain a ferric chloride solution, adding deionized water and anhydrous sodium acetate, stirring evenly and then performing a hydrothermal reaction; (2) centrifuging and drying the material obtained in step (1), and then calcining it in an air atmosphere to obtain a Fe2O3hexagon carrier; (3) dissolving chloroplatinic acid hexahydrate in deionized water to obtain a chloroplatinic acid solution, then adding the Fe2O3hexagon carrier thereto, stirring and dispersing, and then adding a sodium borohydride solution to react by stirring at room temperature; (4) centrifuging and drying the material obtained in step (3), and then calcining it in an air atmosphere to obtain the catalyst. The invention does not involve complicated reaction and operation steps, and is easy to operate and repeat.

Description

Technical Field

[0001] The invention belongs to the technical field of new material preparation, and specifically relates to a preparation method and application of a Pt NPs / Fe2O3hexagon catalyst. Background Art

[0002] Supported precious metal catalysts have been widely studied in the industry due to their superior catalytic activity and stability compared to other transition metal oxide catalysts. For supported precious metal catalysts, the metallic active sites can achieve mutual transfer of electrons between active sites, and this electron transfer can significantly reduce the reaction energy barrier of the catalytic reaction. Therefore, this highly dispersed supported precious metal catalyst with metallic nature generally has better catalytic activity than non-metallic state, and can be used in the fields of removing indoor volatile organic compounds (VOCs) and catalytic oxidation of carbon monoxide (CO). However, the preparation method of supported precious metal catalysts in the prior art is expensive, which limits the application of supported precious metal catalysts in actual working conditions. Summary of the invention

[0003] The purpose of the present invention is to overcome the defects of the prior art and provide a method for preparing a Pt NPs / Fe2O3hexagon catalyst.

[0004] Another object of the present invention is to provide an application of the Pt NPs / Fe2O3hexagon catalyst prepared by the above preparation method.

[0005] The technical solution of the present invention is as follows:

[0006] A method for preparing a Pt NPs / Fe2O3hexagon catalyst comprises the following steps:

[0007] (1) dissolving ferric chloride hexahydrate in anhydrous ethanol by ultrasonication to prepare a ferric chloride solution, adding deionized water and anhydrous sodium acetate, stirring evenly, and then performing a hydrothermal reaction;

[0008] (2) centrifuging and drying the material obtained in step (1), and then calcining it in an air atmosphere to obtain a Fe2O3hexagon carrier with exposed {001} crystal planes;

[0009] (3) dissolving chloroplatinic acid hexahydrate in deionized water to prepare a chloroplatinic acid solution, then adding the Fe2O3hexagon carrier thereto, stirring and dispersing, and then adding a sodium borohydride solution to react by stirring at room temperature;

[0010] (4) The material obtained in step (3) is centrifuged and dried, and then calcined in an air atmosphere to obtain the PtNPs / Fe2O3hexagon catalyst, wherein the Pt loading is 0.2 wt%.

[0011] In a preferred embodiment of the present invention, in step (1), the ratio of ferric chloride hexahydrate, anhydrous ethanol, deionized water and anhydrous sodium acetate is 13.12 g:480 mL:33.6 mL:38.4 g.

[0012] Further preferably, the hydrothermal reaction is carried out at 160-200°C for 10-14 hours.

[0013] More preferably, in step (2), the calcination temperature is 400° C. and the calcination time is 4 hours.

[0014] More preferably, in step (2), the drying temperature is 80°C.

[0015] In a preferred embodiment of the present invention, in the step (3), the mass ratio of the chloroplatinic acid hexahydrate to the sodium borohydride in the sodium borohydride solution is 27:1, and the mass ratio of the chloroplatinic acid hexahydrate to the ferric chloride hexahydrate is 0.0054:13.13.

[0016] Further preferably, in the step (4), the calcination temperature is 200° C. and the calcination time is 2 h.

[0017] More preferably, in step (4), the drying temperature is 120°C.

[0018] The application of the Pt NPs / Fe2O3hexagon catalyst prepared by the above preparation method in removing indoor VOCs.

[0019] Application of the Pt NPs / Fe2O3hexagon catalyst prepared by the above preparation method in CO catalytic oxidation.

[0020] The beneficial effects of the present invention are:

[0021] 1. The present invention does not involve complicated reactions and operation steps and is easy to operate and repeat.

[0022] 2. The present invention utilizes the abundant cation defect sites on Fe2O3hexagon to better anchor Pt atoms, so that Pt can exist stably in a highly dispersed form on the carrier.

[0023] 3. The Pt NPs / Fe2O3hexagon catalyst prepared by the present invention has excellent catalytic performance, and the conversion rate of benzene reaches 90% at 165°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a high-resolution transmission electron microscopy image of the Fe2O3 hexagonal carrier with highly exposed {001} crystal planes prepared in Example 1 of the present invention.

[0025] Figure 2 The infrared CO adsorption experimental spectra of the Pt NPs / Fe2O3hexagon catalyst prepared in Example 1 of the present invention and the comparative catalyst prepared in Example 2 are shown.

[0026] Figure 3 X-ray powder diffraction patterns of the Pt NPs / Fe2O3hexagon catalyst prepared in Example 1 of the present invention and the comparative catalyst prepared in Example 2.

[0027] Figure 4 This is an activity diagram of the Pt NPs / Fe2O3hexagon catalyst prepared in Example 1 of the present invention and the comparative catalyst prepared in Example 2 for catalytic oxidation of benzene. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further illustrated and described below through specific implementation modes in combination with the accompanying drawings.

[0029] Example 1

[0030] A method for preparing a Pt NPs / Fe2O3hexagon catalyst comprises the following steps:

[0031] (1) 13.12 g of ferric chloride hexahydrate was ultrasonically dissolved in 480 mL of anhydrous ethanol to prepare a ferric chloride solution, and 33.4 mL of deionized water and 38.4 g of anhydrous sodium acetate were added. After magnetic stirring, the solution was subjected to a hydrothermal reaction at 180° C. for 12 h.

[0032] (2) The material obtained in step (1) was centrifuged and dried at 80°C, then calcined at 400°C for 4 h in an air atmosphere to obtain Figure 1 Fe2O3hexagon support with exposed {001} facets shown;

[0033] (3) 0.0054 g of chloroplatinic acid hexahydrate was dissolved in deionized water to prepare a chloroplatinic acid solution, and then the Fe2O3hexagon carrier was added thereto, stirred and dispersed, and then a sodium borohydride solution (containing 0.002 g of sodium borohydride, the solvent was deionized water) was added to carry out a magnetic stirring reaction at room temperature;

[0034] (4) The material obtained in step (3) is centrifuged and dried at 120° C., then placed in an air atmosphere and calcined at 200° C. for 2 h to obtain the Pt NPs / Fe2O3hexagon catalyst, wherein the Pt loading is 0.2 wt%.

[0035] Example 2

[0036] The difference from Example 1 is that no sodium borohydride solution is added in step (3) to obtain a comparative catalyst (Pt ox / Fe2O3hexagon catalyst).

[0037] Example 3

[0038] The Pt NPs / Fe2O3hexagon catalyst prepared in Example 1 and the comparative catalyst prepared in Example 2 were subjected to infrared CO adsorption test analysis, and the comparative results are shown in FIG. Figure 2 As shown. Figure 2 It can be seen that in the Pt NPs / Fe2O3hexagon catalyst prepared in Example 1, the vibration frequency of CO linearly adsorbed on metallic Pt is 2085 cm -1 , which is lower than 2090cm in the non-metallic state. -1 It can be observed from the local magnified image that as the CO coverage decreases, the vibration frequency of CO linearly adsorbed on the metallic Pt gradually red-shifts. This is a unique phenomenon in the metallic state and does not occur on the non-metallic Pt of the comparison catalyst in Example 2.

[0039] Example 4

[0040] In order to verify the success of the prepared catalyst and the state of Pt on its surface, the Pt NPs / Fe2O3hexagon catalyst prepared in Example 1 and the comparative catalyst prepared in Example 2 were subjected to X-ray powder diffraction analysis. The results are as follows: Figure 3 shown.

[0041] from Figure 3 It can be seen that all the diffraction peaks of the catalyst sample belong to the corresponding crystal plane of Fe2O3, and there is no relevant diffraction peak of Pt in the spectrum, indicating that in the prepared catalyst, Pt is highly dispersed on the carrier surface in the form of tiny particles.

[0042] Example 5

[0043] The Pt NPs / Fe2O3hexagon catalyst prepared in Example 1 and the comparative catalyst prepared in Example 2 were pressed into tablets and passed through a 40-60 mesh sieve. Then, 0.1 g of each was taken into a quartz tube with an inner diameter of 0.6 mm. A mixed gas of 0.05 vol% benzene, 20 vol% O2, and balance gas N2 was introduced at a total flow rate of 100 mL min -1 The reactor temperature was raised to 350°C and the gas after the reaction was sent to the gas chromatograph to analyze the catalytic performance of the catalyst. Figure 4 shown.

[0044] from Figure 4 It can be seen that compared with the comparison catalyst loaded with non-metallic Pt, the PtNPs / Fe2O3hexagon catalyst loaded with metallic Pt has better catalytic oxidation performance of benzene, among which the conversion rate of benzene reaches 90% at 165°C.

[0045] The above description is only a preferred embodiment of the present invention, and therefore cannot be used to limit the scope of the present invention. That is, equivalent changes and modifications made according to the patent scope of the present invention and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A method for preparing a Pt NPs / Fe2O3 hexagon catalyst, characterized in that: The steps include: (1) Dissolving ferric chloride hexahydrate in anhydrous ethanol by ultrasonication to obtain a ferric chloride solution, and adding deionized water and anhydrous sodium acetate, stirring evenly and then performing a hydrothermal reaction at 160-200°C for 10-14h; the ratio of ferric chloride hexahydrate, anhydrous ethanol, deionized water and anhydrous sodium acetate is 13.12g: 480mL: 33.6mL: 38.4g; (2) the material obtained in step (1) was centrifuged and dried at 80°C, and then calcined at 400°C for 4 h in an air atmosphere to obtain a Fe2O3 hexagon carrier with exposed {001} crystal planes; (3) dissolving chloroplatinic acid hexahydrate in deionized water to prepare a chloroplatinic acid solution, then adding the above-mentioned Fe2O3hexagon carrier thereto, stirring and dispersing, and then adding a sodium borohydride solution to react by stirring at room temperature; the mass ratio of chloroplatinic acid hexahydrate to sodium borohydride in the sodium borohydride solution is 27:1, and the mass ratio of chloroplatinic acid hexahydrate to ferric chloride hexahydrate is 0.0054:13.13; (4) The material obtained in step (3) was centrifuged and dried at 120° C., and then calcined at 200° C. for 2 h in an air atmosphere to obtain the Pt NPs / Fe2O3 hexagon catalyst, wherein the Pt loading was 0.2 wt%.

2. Application of the Pt NPs / Fe2O3 hexagon catalyst prepared by the preparation method of claim 1 in removing indoor VOCs.

3. Use of the Pt NPs / Fe2O3hexagon catalyst prepared by the preparation method according to claim 1 in CO catalytic oxidation.

Images