Preparation method and application of indium oxide catalyst

Abstract

The invention relates to a preparation method and application of an indium oxide catalyst. The preparation method comprises the following steps: 1, mixing and stirring inorganic acid and ethanol to form a mixed solution I; step 2, adding indium nitrate into the mixed solution I, and stirring to form a mixed solution II; 3, pouring the mixed solution II into a hydrothermal reaction kettle, and cooling to room temperature after reaction to form a solution III; 4, adding a template agent into the solution 3, and dissolving to form a mixture solution; 5, transferring the mixture solution into a hydrothermal reaction kettle, cooling to room temperature after hydrothermal reaction, and then separating precipitates in the material; 6, sequentially washing the precipitate with alcohol and water, and separating and drying solid substances; 7, dispersing the solid substance in an absolute ethyl alcohol solution, then condensing and refluxing at 80-100 DEG C for 10-15 hours, and naturally cooling to room temperature; and 8, centrifugally drying the sample, calcining the sample under the condition of H2, and cooling the sample to room temperature to obtain the indium oxide catalyst. The catalytic performance is good.

Description

Technical Field

[0001] The present invention relates to the technical field of photocatalysts, and particularly to a preparation method and application of an indium oxide catalyst. Background Art

[0002] As a major component of indoor VOCs, formaldehyde is derived from various household and industrial products, and long-term exposure poses a serious threat to human health. Traditional methods for formaldehyde removal have limitations such as low efficiency, high cost, and potential secondary pollution. Photocatalytic technology has attracted much attention because it can decompose formaldehyde into harmless substances. The key lies in developing highly efficient, stable, and economical photocatalysts.

[0003] Current research mainly focuses on semiconductor materials such as TiO 2 , ZnO, SnO 2 etc., but they face problems such as narrow light response range, low quantum efficiency, and poor photocatalytic activity. Since the visible light region in the solar spectrum accounts for up to 46%, the development of narrow-bandgap semiconductor materials with visible light absorption and the improvement of optical absorption and utilization of photo-generated carriers for enhancing the photocatalytic degradation efficiency of formaldehyde remain to be explored.

[0004] Indium oxide (In 2 O 3 ) has visible light response and a suitable bandgap position. By regulating its morphology and crystal structure, it is expected to promote the adsorption of formaldehyde molecules, optimize light absorption, charge separation, and transport, and improve photocatalytic activity.

[0005] There are also some reports on indium oxide technology at present. For example, the Chinese invention patent with the patent application number CN202410310519.3 (publication number CN118164522B), "A Composite Morphology Indium Oxide Nanomaterial and Its Application in VOC Gas Detection", discloses a composite morphology indium oxide nanomaterial and its application in VOC gas detection. It uses indium nitrate, urea, and sodium dodecyl sulfate as raw materials, improves on the basis of the hydrothermal reaction principle, and prepares indium oxide nanomaterials with a cluster-like morphology by strictly controlling the raw material ratio and microwave heating treatment. The nanomaterial has a highly dispersed cluster-like structure, and the cluster-like structure is composed of a combination of cube and sheet structures. This structure has a high specific surface area, increases gas adsorption sites, significantly improves the gas-sensing performance of the material, and has excellent sensitivity and selectivity for VOC gas detection, with broad application prospects.

[0006] Therefore, it is necessary for indium oxide catalysts to have a large specific surface area. At the same time, on this basis, if its photocatalytic performance can be improved, it can better play a role in degrading harmful gases such as formaldehyde. Summary of the Invention

[0007] The first technical problem to be solved by the present invention is to provide a preparation method of an indium oxide catalyst for the above-mentioned existing technology, so that the prepared indium oxide catalyst has a large specific surface area and good catalytic performance.

[0008] The second technical problem to be solved by the present invention is to provide an application of the above indium oxide catalyst for the above-mentioned existing technology.

[0009] The technical solution adopted by the present invention to solve the above first technical problem is as follows: A preparation method of an indium oxide catalyst, characterized in that it includes the following steps:

[0010] Step 1: Mix a weakly acidic inorganic acid and ethanol and stir evenly to form a first mixed solution;

[0011] Step 2: Add indium nitrate to the first mixed solution in Step 1 and stir thoroughly to dissolve to form a second mixed solution;

[0012] Step 3: Pour the second mixed solution formed in Step 2 into a hydrothermal reaction kettle, carry out hydrothermal reaction at 150-200 °C for 4-8 h, and then naturally cool to room temperature to form a third solution;

[0013] Step 4: Transfer the third solution to a container, then add a template agent to the third solution and stir to dissolve it to form a mixture solution;

[0014] Step 5: Transfer the mixture solution in Step 4 into a hydrothermal reaction kettle, carry out hydrothermal reaction at 150-200 °C for 8-10 h, naturally cool to room temperature, and then separate the precipitate in the material;

[0015] Step 6: Wash the precipitate in Step 5 with alcohol and water in sequence, separate the solid substance and dry it;

[0016] Step 7: Disperse the solid substance obtained in Step 6 in an anhydrous ethanol solution, then carry out condensation reflux at 80-100 °C for 10-15 h, and naturally cool to room temperature to obtain a sample;

[0017] Step 8: After centrifugally drying the sample obtained in Step 7, heat it to 500-600 °C under H 2 conditions, then calcine it for a set time, and cool it to room temperature to obtain the indium oxide catalyst.

[0018] Preferably, in Step 1, the inorganic acid is acetic acid, so that the hydrolysis reaction has a good effect.

[0019] Preferably, in Step 1, the ethanol is anhydrous ethanol, so that the hydrolysis reaction has a good effect.

[0020] Preferably, in the fourth step, the template agent is the P123 template agent, so that the generated indium oxide catalyst has a good morphology, a large specific surface area, and a large number of active sites.

[0021] Preferably, the mass ratio of the template agent to the addition amount of indium nitrate is (2.5-3.5):1, so that the generated indium oxide catalyst has a coral reef-like morphology. This kind of morphology has a large specific surface area and a large number of active sites.

[0022] The technical solution adopted by the present invention to solve the above second technical problem is as follows: An application of an indium oxide catalyst, characterized in that the indium oxide catalyst is prepared by the above preparation method, and the indium oxide catalyst is used for catalytic decomposition of formaldehyde.

[0023] Compared with the prior art, the advantages of the present invention are as follows: The present invention uses indium nitrate as a raw material, inorganic acid and ethanol as solvents, and undergoes hydrolysis reaction through high-temperature hydrothermal reaction for nucleation and crystal growth; in addition, by adding a template agent, the orderly formation of the indium oxide morphology is controlled, and the precise regulation of the pore structure is realized, thereby increasing the specific surface area of the catalyst, and further promoting the adsorption of gas pollutant molecules; furthermore, through high-temperature calcination, not only InOOH is decomposed into In 2 O 2 O 3 but also part of the oxygen atoms are detached from the lattice, thereby forming oxygen defects in the material. The introduction of oxygen defects further enhances the adsorption of gas pollutant molecules while improving the utilization rate of photo-generated carriers, thereby enhancing the photocatalytic performance of the material.

[0024] Moreover, the preparation method of the present invention requires simple equipment, convenient operation, and good repeatability. The prepared coral reef-like photocatalyst with a unique structure shows excellent performance and good stability in the degradation of formaldehyde. Description of the Drawings

[0025] Figure 1 It is the XRD pattern of indium oxide with oxygen defects prepared in Example 2 of the present invention;

[0026] Figure 2 It is the low-magnification scanning electron microscope image of indium oxide with oxygen defects prepared in Example 2 of the present invention;

[0027] Figure 3 It is the high-magnification scanning electron microscope image of indium oxide with oxygen defects prepared in Example 2 of the present invention;

[0028] Figure 4 It is the EPR pattern of indium oxide with oxygen defects prepared in Example 2 of the present invention;

[0029] Figure 5 It is the photocatalytic degradation activity diagram of formaldehyde in Example 2 of the present invention. Detailed Embodiments

[0030] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be construed as a limitation on the present invention, but rather as a more detailed description of certain aspects, features, and implementation schemes of the present invention.

[0031] For the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0032] All raw materials used in the present invention are commercially available products, and the hydrothermal reaction kettle is purchased from Fuzhou Kelsi Test Equipment Co., Ltd.

[0033] Example 1

[0034] The preparation method of the indium oxide catalyst in this example includes the following steps:

[0035] Step 1: Stir 5 mL of acetic acid and 20 mL of absolute ethanol for 30 min to form a uniformly mixed solution, i.e., mixed solution 1.

[0036] Step 2: Add 0.6 g of indium nitrate to the mixed solution 1 in Step 1 and stir at a speed of 250 r / min for 30 min to fully dissolve and form mixed solution 2. [The addition amount of mixed solution 1 only needs to satisfy the dissolution of indium nitrate. The addition ratio of acetic acid and absolute ethanol is not clearly limited, but the addition amount of acetic acid is less than that of absolute ethanol.

[0037] Step 3: Pour the mixed solution 2 formed in Step 2 into a 50 mL hydrothermal reaction kettle, and heat and react the hydrothermal reaction kettle in an oven at 180 °C for 4 h to carry out the hydrothermal reaction, and then naturally cool to room temperature to form solution 3.

[0038] Step 4: Transfer solution 3 to a container (such as a glass beaker), and then add 1.5 g of P123 template agent to solution 3 and stir at a speed of 250 r / min for 12 h to fully dissolve it to form a mixture solution.

[0039] Step 5: Transfer the mixture solution in Step 4 into a hydrothermal reaction kettle, heat and react the hydrothermal reaction kettle in an oven at 180 °C for 8 h to carry out the hydrothermal reaction, naturally cool to room temperature, and then separate the precipitate in the material.

[0040] Step 6: Wash the precipitate in Step 5 three times each with absolute ethanol and deionized water and then centrifuge it. Place the centrifuged solid substance in a vacuum drying oven and dry it at 60°C for 8 h; that is, after the precipitate is washed with alcohol and water in sequence, the solid substance is separated and dried.

[0041] Step 7: Disperse the solid substance obtained in Step 6 in an absolute ethanol solution, and then carry out condensation reflux at 80°C for 12 h, and naturally cool it to room temperature.

[0042] Step 8: After centrifuging and drying the sample obtained in Step 7, under the condition of H 2 heat, raise the temperature to 500°C at a rate of 5°C / min, keep the temperature constant and calcine for 2 h, and then cool it to room temperature to obtain the indium oxide catalyst.

[0043] Example 2

[0044] The preparation method of the indium oxide catalyst in this example includes the following steps:

[0045] Step 1: Stir 5 mL of acetic acid and 20 mL of absolute ethanol for 30 min to form a uniformly mixed mixture I.

[0046] Step 2: Add 0.6 g of indium nitrate to the mixture I in Step 1, and stir at a speed of 250 r / min for 30 min to fully stir and dissolve to form a mixture II.

[0047] Step 3: Pour the mixture II formed in Step 2 into a 50 mL hydrothermal reaction kettle, and heat and react the hydrothermal reaction kettle in an oven at 180°C for 4 h to carry out hydrothermal reaction, and then naturally cool it to room temperature to form a solution III.

[0048] Step 4: Transfer the solution III to a container (such as a glass beaker), and then add 1.8 g of P123 template agent to the solution III, and stir at a speed of 250 r / min for 12 h to fully dissolve it to form a mixture solution.

[0049] Step 5: Transfer the mixture solution in Step 4 into a hydrothermal reaction kettle, heat and react the hydrothermal reaction kettle in an oven at 180°C for 8 h to carry out hydrothermal reaction, naturally cool it to room temperature, and then separate the precipitate in the material.

[0050] Step 6: Wash the precipitate in Step 5 three times each with absolute ethanol and deionized water and then centrifuge it. Place the centrifuged solid substance in a vacuum drying oven and dry it at 60°C for 8 h; that is, after the precipitate is washed with alcohol and water in sequence, the solid substance is separated and dried.

[0051] Step 7: Disperse the solid substance obtained in Step 6 in an absolute ethanol solution, and then carry out condensation reflux at 80°C for 12 h, and naturally cool it to room temperature.

[0052] Step 8: After centrifuging and drying the sample obtained in Step 7, under H 2 conditions, heat it to 500 °C at a rate of 5 °C / min, keep it at a constant temperature for calcination for 2 h, and then cool it to room temperature to obtain the indium oxide catalyst.

[0053] Example 3

[0054] The preparation method of the indium oxide catalyst in this example includes the following steps:

[0055] Step 1: Stir 5 mL of acetic acid and 20 mL of absolute ethanol for 30 min to form a uniformly mixed solution 1 by mixing and stirring.

[0056] Step 2: Add 0.6 g of indium nitrate to the mixed solution 1 in Step 1, and stir it at a rotation speed of 250 r / min for 30 min to fully dissolve and form a mixed solution 2 by stirring.

[0057] Step 3: Pour the mixed solution 2 formed in Step 2 into a 50 mL hydrothermal reaction kettle, and heat and react it in an oven at 180 °C for 4 h to carry out a hydrothermal reaction, and then naturally cool it to room temperature to form a solution 3.

[0058] Step 4: Transfer the solution 3 to a container (such as a glass beaker), then add 2.1 g of P123 template agent to the solution 3, and stir it at a rotation speed of 250 r / min for 12 h to fully dissolve it and form a mixture solution.

[0059] Step 5: Transfer the mixture solution in Step 4 into a hydrothermal reaction kettle, heat and react it in an oven at 180 °C for 8 h to carry out a hydrothermal reaction, naturally cool it to room temperature, and then separate the precipitate in the material.

[0060] Step 6: Wash the precipitate in Step 5 three times each with absolute ethanol and deionized water and centrifuge it. The centrifuged solid substance is placed in a vacuum drying oven and dried at 60 °C for 8 h; that is, after the precipitate is washed with alcohol and water in sequence, the solid substance is separated and dried.

[0061] Step 7: Disperse the solid substance obtained in Step 6 in an absolute ethanol solution, then carry out condensation reflux at 80 °C for 12 h, and naturally cool it to room temperature.

[0062] Step 8: After centrifuging and drying the sample obtained in Step 7, under H 2 conditions, heat it to 500 °C at a rate of 5 °C / min, keep it at a constant temperature for calcination for 2 h, and then cool it to room temperature to obtain the indium oxide catalyst.

[0063] Example 4

[0064] The preparation method of the indium oxide catalyst in this example includes the following steps:

[0065] Step 1: Stir 5 mL of acetic acid and 20 mL of absolute ethanol for 30 min to form a uniformly mixed solution 1 by thorough mixing and stirring.

[0066] Step 2: Add 0.6 g of indium nitrate to the mixed solution 1 in Step 1 and stir at a rotation speed of 250 r / min for 30 min to form a uniformly dissolved mixed solution 2 by sufficient stirring.

[0067] Step 3: Pour the mixed solution 2 formed in Step 2 into a 50 mL hydrothermal reactor, and heat and react the hydrothermal reactor in an oven at 180 °C for 4 h to carry out the hydrothermal reaction, and then naturally cool to room temperature to form solution 3.

[0068] Step 4: Transfer solution 3 to a container (such as a glass beaker), then add 0.9 g of P123 templating agent to solution 3, and stir at a rotation speed of 250 r / min for 12 h to fully dissolve it to form a mixed solution.

[0069] Step 5: Transfer the mixed solution in Step 4 into a hydrothermal reactor, and heat and react the hydrothermal reactor in an oven at 180 °C for 8 h to carry out the hydrothermal reaction, naturally cool to room temperature, and then separate the precipitate in the material.

[0070] Step 6: Wash the precipitate in Step 5 three times each with absolute ethanol and deionized water and centrifuge it. The centrifuged solid substance is placed in a vacuum drying oven and dried at 60 °C for 8 h; that is, after the precipitate is washed with alcohol and water in sequence, the solid substance is separated and dried.

[0071] Step 7: Disperse the solid substance obtained in Step 6 in an absolute ethanol solution, then condense and reflux at 80 °C for 12 h, and naturally cool to room temperature.

[0072] Step 8: After centrifuging and drying the sample obtained in Step 7, under H 2 conditions, heat it to 500 °C at a rate of 5 °C / min, keep it at a constant temperature and calcine for 2 h, and then cool to room temperature to obtain the indium oxide catalyst.

[0073] Example 5

[0074] The preparation method of the indium oxide catalyst in this example includes the following steps:

[0075] Step 1: Stir 5 mL of acetic acid and 20 mL of absolute ethanol for 30 min to form a uniformly mixed solution 1 by thorough mixing and stirring.

[0076] Step 2: Add 0.6 g of indium nitrate to the mixed solution 1 in Step 1 and stir at a rotation speed of 250 r / min for 30 min to form a uniformly dissolved mixed solution 2 by sufficient stirring.

[0077] Step 3: Pour the second mixture solution formed in Step 2 into a 50 mL hydrothermal reactor, and heat the hydrothermal reactor in an oven at 180 °C for 4 h to carry out the hydrothermal reaction, and then naturally cool it to room temperature to form solution three;

[0078] Step 4: Transfer solution three to a container (such as a glass beaker), and then add 3.0 g of P123 template agent to solution three, and stir it at a speed of 250 r / min for 12 h to fully dissolve it to form a mixture solution;

[0079] Step 5: Transfer the mixture solution in Step 4 into a hydrothermal reactor, and heat the hydrothermal reactor in an oven at 180 °C for 8 h to carry out the hydrothermal reaction, naturally cool it to room temperature, and then separate the precipitate in the material;

[0080] Step 6: Wash the precipitate in Step 5 three times each with absolute ethanol and deionized water and centrifuge it. The centrifuged solid substance is placed in a vacuum drying oven and dried at 60 °C for 8 h; that is, after the precipitate is washed with alcohol and water in sequence, the solid substance is separated and dried;

[0081] Step 7: Disperse the solid substance obtained in Step 6 in an absolute ethanol solution, and then carry out condensation reflux at 80 °C for 12 h and naturally cool it to room temperature;

[0082] Step 8: After centrifuging and drying the sample obtained in Step 7, under the condition of H 2 heat it from room temperature to 500 °C at a rate of 5 °C / min, keep it at a constant temperature and calcine it for 2 h, and then cool it to room temperature to obtain the indium oxide catalyst.

[0083] In the above Example 4, because the addition amount of the P123 template agent is small, and in Example 5, because the addition amount of the P123 template agent is large, the indium oxide catalyst formed has an irregular morphology structure and is not a coral reef-like structure.

[0084] The present invention tested the catalytic decomposition performance of the indium oxide catalysts prepared in the above examples for formaldehyde, and Example 1 is used for illustration:

[0085] Coat the indium oxide catalyst on an acrylic board, and the preparation method includes the following steps:

[0086] (1) Place a 20*20 cm acrylic board in ethanol and ultrasonicate it for 60 min, then rinse it with deionized water and dry it at room temperature.

[0087] (2) Weigh 1 g of the indium oxide catalyst prepared in Example 1 and put it into a 20 mL glass vial, add 0.5 mL of Nafion solution [perfluorosulfonic acid-based polymer solution] + 9.5 mL of alcohol-water mixture (volume ratio of ethanol to water is 1:1), and ultrasonically disperse it in an ultrasonic cleaner for 1 h to form a suspension.

[0088] (3) The dispersed suspension in step (2) is evenly spin-coated on the acrylic plate treated in step (1) and dried at room temperature for evaluating the photocatalytic activity of the catalyst for degrading formaldehyde.

[0089] The test method for the photocatalytic degradation performance of formaldehyde is as follows:

[0090] A self-made sealed experimental platform for photocatalytic degradation of formaldehyde is adopted. The experimental platform consists of two units: a formaldehyde generation chamber and an environmental simulation chamber. The acrylic plate coated with indium oxide catalyst in step (3) is placed in the environmental simulation chamber, and formaldehyde solution is introduced into the formaldehyde generation chamber. The volatilized and diffused formaldehyde gas is pumped into the sealed environmental simulation chamber for photocatalytic reaction by means of a suction pump, and the formaldehyde content in the environmental simulation chamber is controlled to reach 1 mg / m 3 . After standing for half an hour, the ultraviolet lamp is turned on for illumination for 2 h, and the photocatalytic degradation performance of the prepared indium oxide catalyst for formaldehyde is evaluated by reading the indication of the formaldehyde detector in the environmental simulation chamber.

[0091] After testing, under 2 h of illumination, the prepared coral reef-like In with oxygen defects 2 O 3 has a formaldehyde degradation efficiency of over 75%, and maintains a stable degradation efficiency after multiple cycles. This indium oxide photocatalytic material has good photocatalytic degradation performance for formaldehyde.

Claims

1. A method for preparing an indium oxide catalyst, characterized in that: The steps include: Step 1: Mix a weakly acidic inorganic acid and ethanol and stir them evenly to form a mixed solution 1; Step 2: adding indium nitrate to the mixed solution 1 of step 1, stirring and dissolving to form a mixed solution 2; Step 3: Pour the mixed solution 2 formed in step 2 into a hydrothermal reaction kettle, perform hydrothermal reaction at 150-200° C. for 4-8 hours, and then cool to room temperature to form solution 3; Step 4: Transfer solution 3 to a container, then add the template into solution 3, and stir to dissolve it to form a mixture solution; Step 5: transfer the mixture solution in step 4 into a hydrothermal reactor, perform hydrothermal reaction at 150-200° C. for 8-10 hours, cool to room temperature, and then separate the precipitate from the material; Step 6: washing the precipitate in step 5 with alcohol and water in turn, separating the solid matter and drying it; Step 7: Disperse the solid substance obtained in step 6 in an anhydrous ethanol solution, then condense and reflux at 80-100° C. for 10-15 hours, and cool to room temperature; Step 8: After centrifugation and drying of the sample obtained in step 7, the temperature is raised to 500-600° C. under H2 conditions, calcined within a set time, and then cooled to room temperature to obtain the indium oxide catalyst.

2. The method for preparing an indium oxide catalyst according to claim 1, characterized in that: In the step 1, the inorganic acid is acetic acid.

3. The method for preparing an indium oxide catalyst according to claim 1, characterized in that: In the step 1, the ethanol is anhydrous ethanol.

4. The method for preparing an indium oxide catalyst according to claim 1, characterized in that: In the step 4, the template is a P123 template.

5. The method for preparing an indium oxide catalyst according to claim 1, characterized in that: The mass ratio of the template agent to the indium nitrate added is (2.5-3.5):

1.

6. An application of an indium oxide catalyst, characterized in that: The indium oxide catalyst is prepared by the method described in any one of claims 1 to 5, and the indium oxide catalyst is used for decomposing and catalyzing formaldehyde.

Images