Preparation method of nickel-based red mud material and its application in concentrated photocatalysis

Abstract

The present invention relates to the technical field of nickel-based red mud material preparation, specifically the preparation method of nickel-based red mud material and its application in concentrated photocatalysis, and its preparation step includes: S1. red mud carrier pretreatment; S2. nickel nitrate hexahydrate is dissolved in a modified dispersant, stirred to clarify, and a modified nickel salt solution is obtained; S3. the modified red mud carrier is slowly added to the modified nickel salt solution with magnetic stirring, and then ultrasonically dispersed to form a suspension; S4. the suspension is transferred to an oil bath pot for heating, continuously stirred until the water evaporates, and ground after naturally cooling to room temperature. The ground solid product is placed in a muffle furnace and heated to 400-600°C, and calcined under an air atmosphere to finally obtain a nickel-based red mud material. The preparation method of the present invention is simple, low in cost, and has a wide range of raw material sources, with good industrial application prospects. Compared with traditional precious metal catalysts, not only is the cost lower, but also under high temperature reaction conditions, it shows more excellent anti-sintering and anti-carbon deposition performance.

Description

Technical Field

[0001] The present invention relates to the technical field of nickel-based red mud material preparation, in particular to a method for preparing nickel-based red mud material and its application in concentrated photocatalysis. Background Art

[0002] Solar energy has significant advantages such as being clean, safe, inexhaustible and inexhaustible. However, it has the problem of uneven temporal and spatial distribution, making it basically impossible to obtain the maximum solar energy reception effect for stable photothermal conversion and utilization.

[0003] Methane (CH4), a core component of natural gas, contributes increasingly to energy consumption, and research on its efficient development and utilization is attracting widespread attention. Furthermore, the widespread use of fossil fuels has triggered the emission of large quantities of greenhouse gases, including carbon dioxide (CO2), exacerbating the greenhouse effect and posing a serious threat to the global ecological environment. Methane-CO2 dry reforming (DRM) is a highly efficient conversion pathway that combines environmental and economic benefits, converting CH4 and CO2 into synthesis gas (syngas). This process not only expands the application range of methane but also consumes two major greenhouse gases. Furthermore, the resulting synthesis gas has a near 1:1 ratio of hydrogen (H2) to carbon monoxide (CO), making it ideal for direct production of high-value-added chemicals. However, the DRM reaction is endothermic and typically requires high temperatures, which can be significantly reduced using catalysts. While noble metal catalysts exhibit excellent catalytic activity and stability in the DRM reaction, their high cost limits their large-scale application.

[0004] Traditional photothermal catalytic methane dry reforming requires high temperatures exceeding 600°C. However, Northwest my country, with its vast expanse and limited sunlight, cannot achieve this high-temperature dry reforming reaction, making it unsuitable for this region. Therefore, developing a methane dry reforming reaction at 400-500°C could effectively leverage the region's solar energy resources. If a new photothermal catalyst could be developed that could harness solar energy to achieve low-temperature catalysis, it would maximize the region's sunlight availability and produce high-energy synthesis gas. Red mud (RM) is a major solid waste emitted during alumina production. It is a highly alkaline, reddish, muddy residue. Due to its diverse composition and complex phases, RM offers advantages as a catalyst, including low cost, widespread availability, numerous active sites, high adjustability, and environmental friendliness, enabling efficient resource reuse. Summary of the Invention

[0005] In view of the problem that nickel-based catalysts for DRM reactions in the prior art suffer from serious sintering and carbon deposition deactivation under high-temperature reaction conditions, the purpose of the present invention is to provide a method for preparing a nickel-based red mud material and its application in concentrated photocatalysis. The nickel-based red mud material catalyst uses modified red mud as a carrier of Ni, which can create abundant active sites and strong metal-carrier interactions, thereby improving the catalytic activity of the nickel-based red mud material catalyst for the methane-carbon dioxide dry reforming reaction. Moreover, by washing the carrier with water, the activity inhibitory effect of alkalinity on red mud can be further alleviated, so that the catalyst has high catalytic activity and good stability.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for preparing a nickel-based red mud material comprises the following steps:

[0008] S1. Red mud carrier pretreatment:

[0009] S11. According to parts by mass, 7-10 parts of red mud powder were added to 500-600 parts of the modified modifier, ultrasonically dispersed at a frequency of 40 kHz for 20-30 min, allowed to stand overnight, the supernatant was discarded, and the solid was separated by centrifugation;

[0010] S12. The solid separated in step S11 is placed in an oven and dried for 8-12h, then taken out and ground into a fine powder;

[0011] S13. The powder was ground into a fine powder and passed through an 80-mesh sieve and placed in a muffle furnace. The temperature was slowly raised to 700-900 ° C and calcined in an air atmosphere for 2-4h. The modified red mud carrier was obtained by cooling;

[0012] S2 0.05-1 parts of nickel nitrate hexahydrate is dissolved in 30-50 parts of the modified dispersant and stirred for 10-20min until clear to obtain a modified nickel salt solution;

[0013] S3. Take 0.5-1 parts of the modified red mud carrier and slowly add it to the modified nickel salt solution, magnetically stir at a speed of 300-500r / min for 5-10min, and then ultrasonically disperse for 30-60min to form a suspension;

[0014] S4. The suspension was transferred to an oil bath, heated for 10-12 hours, stirred continuously until the water evaporated, cooled naturally to room temperature, and then ground. The ground solid product was placed in a muffle furnace, heated to 400-600°C at 2-5°C / min, and calcined in air for 2-4 hours to obtain a nickel-based red mud material.

[0015] The preparation of the modified modifier comprises the following steps:

[0016] S111. In parts by mass, 500-600 parts of deionized water were added, 10-15 parts of concentrated nitric acid and 5-8 parts of citric acid, and stirred at a speed of 300-400 r / min in a water bath at 60 ° C for 5-10min to obtain an acidic etching solution;

[0017] S112 was added to the acidic etching solution 10-15 parts of a surface modifier, ultrasonic dispersion at a frequency of 40kHz for 15-20min to obtain a preliminary modified modifier;

[0018] S113. Ammonia water is added to the preliminary modified modifier to adjust the pH, and then 45-50 parts of isopropanol are added. The mixture is stirred at a constant temperature of 45° C. and a speed of 300-400 r / min for 20-30 min, and the modified modifier is obtained by filtration.

[0019] Preferably, the preparation of the surface modifier comprises the following steps:

[0020] S1121. According to parts by mass, 2-5 parts of trisodium citrate were added to 300-400 parts of deionized water, and stirred at a speed of 300-400r / min in a water bath at 60°C until completely dissolved;

[0021] S1122. To the solution obtained in step S1121, 1.5-3 parts of hexadecyltrimethylammonium bromide and 0.8-1.5 parts of disodium ethylenediaminetetraacetate were added, and ultrasonic dispersion was performed at 45°C for 15-20 minutes to obtain a preliminary modified solution;

[0022] S1123. Add 3-5 parts of KH-550 to the preliminary modified solution and stir at a speed of 450-500 r / min for 20-30 min to form a milky white emulsion;

[0023] S1124. Add 0.5-1 parts of polyethylene glycol-6000 and 80-100 parts of isopropyl alcohol to the milky white emulsion, and stir at a constant temperature of 40° C. for 10-15 minutes to finally obtain a surface modifier.

[0024] Preferably, the preparation of the modified dispersant comprises the following steps:

[0025] S21. In parts by mass, 20-25 parts of acetylacetone and 90-100 parts of ethylene glycol were mixed and stirred at 300-400 r / min at 40 ° C for 8-10 min;

[0026] S22. To the solution obtained in step S21, 8-10 parts of polyethylene glycol-4000 and 0.1-0.5 parts of cerium nitrate were added and ultrasonically dispersed at a frequency of 40 kHz for 10-15 min to obtain a preliminary dispersion;

[0027] S23. Tetramethylammonium hydroxide is added to the preliminary dispersion to adjust the pH to 8.2-8.8, thereby obtaining a modified dispersant.

[0028] Preferably, the rate of slowly heating in step S13 is 2-5°C / min.

[0029] Preferably, the drying temperature in step S12 is 60-80°C.

[0030] Preferably, the stirring speed in step S2 is 300-400 r / min.

[0031] Preferably, the heating temperature in step S4 is maintained at 70-100°C.

[0032] Preferably, the pH in step S113 is controlled in the range of 3.8-4.2.

[0033] Preferably, the pH in step S23 is controlled in the range of 8.2-8.8.

[0034] The nickel-based red mud material prepared according to the above preparation method is used in the photocatalytic conversion of methane and carbon dioxide.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] 1. The present invention uses the synergistic effect of modified modifiers and modified dispersants to make the obtained nickel-based red mud material catalyst have abundant active sites and strong metal-support interactions, which significantly improves the catalytic activity against DRM. By modifying the red mud support, the inhibitory effect of the support's alkalinity on the catalyst activity can be effectively alleviated, further improving the performance of the catalyst. In addition, the present invention adopts ultrasound-assisted dispersion technology during the preparation process to ensure the uniform distribution of red mud in the solution, thereby enhancing the number and dispersibility of the catalyst's active sites. During the high-temperature roasting process, the porous structure of the red mud support is retained, providing more adsorption and reaction sites for the reactants, further improving the activity and stability of the catalyst.

[0037] 2. The nickel-based red mud material catalyst of the present invention has a simple preparation method, low cost, and a wide range of raw material sources, and has good prospects for industrial application. Compared with traditional precious metal catalysts, the nickel-based red mud material of the present invention is not only lower in cost, but also exhibits better resistance to sintering and carbon deposition under high-temperature reaction conditions. By optimizing the preparation process, such as controlling the water washing time, drying temperature, roasting conditions, etc., the performance of the catalyst is further improved. Experimental results show that the nickel-based red mud material catalyst of the present invention can effectively convert methane and carbon dioxide into synthesis gas in the DRM reaction, and the ratio of hydrogen to carbon monoxide in the generated synthesis gas is close to 1:1, which is very suitable for the production of high-value-added chemicals. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a flow chart of the preparation process of the nickel-based red mud material of the present invention;

[0039] Figure 2 The UV-visible spectra of the nickel-based red mud material and ordinary red mud powder obtained in Examples 1-2 of the present invention are shown;

[0040] Figure 3 This is a performance diagram of the CH4 conversion rate of the nickel-based red mud material obtained in Example 2-3 of the present invention in the methane-carbon dioxide dry reforming reaction;

[0041] Figure 4 This is a performance diagram of the CO2 conversion rate of the nickel-based red mud material obtained in Example 2-3 of the present invention in the methane-carbon dioxide dry reforming reaction;

[0042] Figure 5 The XRD patterns of the nickel-based red mud material and ordinary red mud powder obtained in Examples 1-2 of the present invention are shown. DETAILED DESCRIPTION

[0043] The present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0044] See also Figure 1-5 , the present invention provides a technical solution:

[0045] Example 1

[0046] A method for preparing nickel-based red mud material:

[0047] Before preparing nickel-based red mud materials, surface modifiers, modification modifiers, and modified dispersants are prepared:

[0048] The preparation of the surface modifier comprises the following steps:

[0049] S1121. Add 2 g of trisodium citrate to 300 g of deionized water and stir at 300 rpm in a 60 ° C water bath until completely dissolved.

[0050] S1122. Add 1.5 g of hexadecyltrimethylammonium bromide and 0.8 g of disodium ethylenediaminetetraacetate to the solution obtained in step S1121, and ultrasonically disperse at 45° C. for 15 min to obtain a preliminary modified solution;

[0051] S1123. Add 3gKH-550 to the preliminary modified solution and stir at 450r / min for 20min to form a milky white emulsion;

[0052] S1124. Add 0.5 g of polyethylene glycol-6000 and 80 g of isopropyl alcohol to the milky white emulsion, and stir at a constant temperature of 40° C. for 10-15 minutes to finally obtain a surface modifier.

[0053] The preparation of the modified modifier comprises the following steps:

[0054] S111. Take 500g of deionized water, add 10g of concentrated nitric acid and 5g of citric acid, and stir at a speed of 300r / min in a water bath heated at 60°C for 5min to obtain an acidic etching solution;

[0055] S112 was added to the acidic etching solution 10g of surface modifier, ultrasonic dispersion at a frequency of 40kHz for 15min to obtain a preliminary modified modifier;

[0056] S113. Ammonia water was added to the preliminary modified modifier to adjust the pH to 3.8, and then 45 g of isopropanol was added. The mixture was stirred at a constant temperature of 45° C. and a speed of 300 r / min for 20 min, and the modified modifier was obtained by filtration.

[0057] The preparation of the modified dispersant comprises the following steps:

[0058] S21. 20 g of acetylacetone was mixed with 90 g of ethylene glycol and stirred at 300 rpm for 8 min at 40 ° C.

[0059] S22. To the solution obtained in step S21, 8 g of polyethylene glycol-4000 and 0.1 g of cerium nitrate were added and ultrasonically dispersed at a frequency of 40 kHz for 10 min to obtain a preliminary dispersion;

[0060] S23. Tetramethylammonium hydroxide was added to the preliminary dispersion to adjust the pH to 8.2, and finally a modified dispersant was obtained.

[0061] S1. Red mud carrier pretreatment:

[0062] S11. 7 g of red mud powder was added to 500 g of the modified modifier and ultrasonically dispersed at a frequency of 40 kHz for 20 min. After standing overnight, the supernatant was discarded and the solid was separated by centrifugation.

[0063] S12. The solid separated in step S11 was placed in an oven and dried at 60°C for 8 hours, then ground into a fine powder;

[0064] S13. The powder was ground into a fine powder and passed through an 80-mesh sieve. The powder was placed in a muffle furnace and heated to 700°C at a heating rate of 2°C / min and calcined in an air atmosphere for 2 h. The modified red mud carrier was obtained after cooling.

[0065] S2 0.05g of nickel nitrate hexahydrate was dissolved in 30g of the modified dispersant and stirred at 300r / min for 10min until clarified to obtain a modified nickel salt solution;

[0066] S3. Take 0.5g of modified red mud carrier and slowly add it to the modified nickel salt solution, stir magnetically at a speed of 300r / min for 5min, and then ultrasonically disperse for 30min to form a suspension;

[0067] S4. The suspension was transferred to an oil bath and heated at 70°C for 10 h with continuous stirring until the water evaporated. The suspension was naturally cooled to room temperature and then ground. The ground solid product was placed in a muffle furnace and heated to 400°C at a rate of 2°C / min. The product was calcined in air for 2 h to obtain a nickel-based red mud material with a nickel content of 1%.

[0068] Example 2

[0069] A method for preparing nickel-based red mud material:

[0070] Before preparing nickel-based red mud materials, surface modifiers, modification modifiers, and modified dispersants are prepared:

[0071] The preparation of the surface modifier comprises the following steps:

[0072] S1121. Add 5 g of trisodium citrate to 400 g of deionized water and stir at 400 rpm in a 60 ° C water bath until completely dissolved.

[0073] S1122. Add 3 g of hexadecyltrimethylammonium bromide and 1.5 g of disodium ethylenediaminetetraacetate to the solution obtained in step S1121, and ultrasonically disperse at 45° C. for 20 min to obtain a preliminary modified solution;

[0074] S1123. 5 g KH-550 was added to the preliminary modified solution and stirred at 500 r / min for 30 min to form a milky white emulsion;

[0075] S1124. Add 1 g of polyethylene glycol-6000 and 100 g of isopropyl alcohol to the milky white emulsion, and stir at a constant temperature of 40° C. for 15 minutes to finally obtain a surface modifier.

[0076] The preparation of the modified modifier comprises the following steps:

[0077] S111. Take 600g of deionized water, add 15g of concentrated nitric acid and 8g of citric acid, and stir at a speed of 400r / min in a water bath heated at 60°C for 10min to obtain an acidic etching solution;

[0078] S112 was added to the acidic etching solution 15g of surface modifier, ultrasonic dispersion at a frequency of 40kHz for 20min to obtain a preliminary modified modifier;

[0079] S113. Ammonia water was added to the preliminary modified modifier to adjust the pH to 4.2, and then 50 g of isopropanol was added. The mixture was stirred at a constant temperature of 45° C. and a speed of 400 r / min for 30 min, and the modified modifier was obtained by filtration.

[0080] The preparation of the modified dispersant comprises the following steps:

[0081] S21. 25 g of acetylacetone was mixed with 100 g of ethylene glycol and stirred at 400 rpm for 10 min at 40 ° C.

[0082] S22. To the solution obtained in step S21, 10 g of polyethylene glycol-4000 and 0.5 g of cerium nitrate were added and ultrasonically dispersed at a frequency of 40 kHz for 15 min to obtain a preliminary dispersion;

[0083] S23. Tetramethylammonium hydroxide was added to the preliminary dispersion to adjust the pH to 8.8, thereby obtaining a modified dispersant.

[0084] S1. Red mud carrier pretreatment:

[0085] S11. 10 g of red mud powder was added to 600 g of the modified modifier and ultrasonically dispersed at a frequency of 40 kHz for 30 min. After standing overnight, the supernatant was discarded and the solid was separated by centrifugation.

[0086] S12. The solid separated in step S11 was placed in an oven and dried at 80°C for 12 hours, then ground into a fine powder;

[0087] S13. The powder was ground into a fine powder and passed through an 80-mesh sieve. The powder was placed in a muffle furnace, heated to 900°C at a heating rate of 5°C / min and calcined in an air atmosphere for 4 h. The modified red mud carrier was obtained after cooling.

[0088] S2 0.2477g of nickel nitrate hexahydrate was dissolved in 50g of the modified dispersant and stirred at a speed of 400r / min for 20min until clarified to obtain a modified nickel salt solution;

[0089] S3. Take 0.55g of modified red mud carrier and slowly add it to the modified nickel salt solution, stir magnetically at a speed of 500r / min for 10min, and then ultrasonically disperse for 60min to form a suspension;

[0090] S4. The suspension was transferred to an oil bath and heated at 100°C for 12 hours with continuous stirring until the water evaporated. The suspension was naturally cooled to room temperature and then ground. The ground solid product was placed in a muffle furnace and heated to 600°C at a rate of 5°C / min. The product was calcined in air for 4 hours to obtain a nickel-based red mud material with a nickel content of 5%.

[0091] Example 3

[0092] A method for preparing nickel-based red mud material:

[0093] Before preparing nickel-based red mud materials, surface modifiers, modification modifiers, and modified dispersants are prepared:

[0094] The preparation of the surface modifier comprises the following steps:

[0095] S1121. Add 4 g of trisodium citrate to 350 g of deionized water and stir at 350 rpm in a 60 ° C water bath until completely dissolved.

[0096] S1122. Add 2 g of hexadecyltrimethylammonium bromide and 1.1 g of disodium ethylenediaminetetraacetate to the solution obtained in step S1121, and ultrasonically disperse at 45° C. for 17 min to obtain a preliminary modified solution;

[0097] S1123. 4 g KH-550 was added to the preliminary modified solution and stirred at 470 r / min for 25 min to form a milky white emulsion;

[0098] S1124. Add 0.7 g of polyethylene glycol-6000 and 90 g of isopropyl alcohol to the milky white emulsion, and stir at a constant temperature of 40° C. for 12 minutes to finally obtain a surface modifier.

[0099] The preparation of the modified modifier comprises the following steps:

[0100] S111. Take 550g of deionized water, add 13g of concentrated nitric acid and 7g of citric acid, stir at a speed of 350r / min in a water bath heated at 60°C for 8min to obtain an acidic etching solution;

[0101] S112 was added to the acidic etching solution 14g of surface modifier, ultrasonic dispersion at a frequency of 40kHz for 15-20min to obtain a preliminary modified modifier;

[0102] S113. Ammonia water was added to the preliminary modified modifier to adjust the pH to 4, and then 48 g of isopropanol was added. The mixture was stirred at a constant temperature of 45° C. and a speed of 350 r / min for 25 min, and the modified modifier was obtained by filtration.

[0103] The preparation of the modified dispersant comprises the following steps:

[0104] S21. 23 g of acetylacetone was mixed with 95 g of ethylene glycol and stirred at 350 rpm for 9 min at 40 ° C.

[0105] S22. To the solution obtained in step S21, 9 g of polyethylene glycol-4000 and 0.3 g of cerium nitrate were added and ultrasonically dispersed at a frequency of 40 kHz for 13 min to obtain a preliminary dispersion;

[0106] S23. Tetramethylammonium hydroxide was added to the preliminary dispersion to adjust the pH to 8.5, thereby obtaining a modified dispersant.

[0107] S1. Red mud carrier pretreatment:

[0108] S11. 9 g of red mud powder was added to 550 g of the modified modifier and ultrasonically dispersed at a frequency of 40 kHz for 25 min. After standing overnight, the supernatant was discarded and the solid was separated by centrifugation.

[0109] S12. The solid separated in step S11 was placed in an oven and dried at 70°C for 10 hours, then ground into a fine powder;

[0110] S13. The powder was ground into a fine powder and passed through an 80-mesh sieve. The powder was placed in a muffle furnace and heated to 800°C at a heating rate of 2-5°C / min and calcined in an air atmosphere for 3 h. The modified red mud carrier was obtained after cooling.

[0111] S2 1g of nickel nitrate hexahydrate was dissolved in 40g of the modified dispersant and stirred at a speed of 350r / min for 15min until clarified to obtain a modified nickel salt solution;

[0112] S3. 0.9 g of the modified red mud carrier was slowly added to the modified nickel salt solution, magnetically stirred at a speed of 300-500 r / min for 9 min, and then ultrasonically dispersed for 50 min to form a suspension;

[0113] S4. The suspension was transferred to an oil bath and heated at 80°C for 11 hours with continuous stirring until the water evaporated. The suspension was naturally cooled to room temperature and then ground. The ground solid product was placed in a muffle furnace and heated to 500°C at a rate of 4°C / min. The product was calcined in air for 3 hours to obtain a nickel-based red mud material with a nickel content of 20%.

[0114] Performance testing:

[0115] Take 50 mg of the nickel-based red mud material obtained in Examples 2-3 and mix it with quartz sand. Then put it into a quartz reaction tube. Fill the upstream with quartz wool to prevent the loss of the nickel-based red mud material catalyst. Introduce N2 at a flow rate of 20 mL / min. After 1 hour, remove impurities and switch to H2 / N2 mixed gas (10% H2, flow rate of 20 mL / min). After 2 hours of reduction, activate it. Then introduce the reaction gas CH4:CO2=1:1 (total flow rate 40 mL / min), turn on the focusing system (light intensity ≥1 kW / m²), and sample and analyze the outlet gas composition every 30 minutes using an online gas chromatograph for ≥10 hours.

[0116] CH4 conversion rate (%) is: ;

[0117] CO2 conversion rate (%) is: .

[0118] The obtained CH4 conversion performance diagram in the methane-carbon dioxide dry reforming reaction and the CO2 conversion performance diagram in the methane-carbon dioxide dry reforming reaction are shown in the attached figure. Figure 3 and attached Figure 4 As shown. Figure 3 It can be seen that when the nickel content is 20%, the material has the best CH4 conversion performance in the methane-carbon dioxide dry reforming reaction. As the xenon lamp current increases and the test time lengthens, the catalytic activity steadily increases and no deactivation occurs. Figure 4 and Figure 3 Correspondingly, the conversion performance of the three nickel-based red mud material catalysts for CO2 is presented. The CO2 conversion rate trend is highly synchronized with that of CH4. The CO2 conversion rate of the nickel-based red mud material of Example 3 (Ni content is 20%) is >80%.

[0119] The nickel-based red mud material (nickel content of 1%) obtained in Example 1 and the nickel-based red mud material (nickel content of 5%) obtained in Example 2 have similar activities and are weaker in activity. Therefore, in the performance test of CH4 conversion rate and CO2 conversion rate in the methane-carbon dioxide dry reforming reaction, the nickel-based red mud material obtained in Example 2 was selected for the experiment, and Example 1 was omitted.

[0120] By attaching Figure 5 The XRD patterns of the nickel-based red mud material and red mud powder obtained in Examples 1-2 show that the original red mud mainly contains hematite (Fe2O3, PDF#33-0664), hydrated aluminosilicate, etc. After modification, the characteristic peaks of hematite (2θ≈33°, 35°) still exist, and NiO characteristic peaks appear at 2θ≈37° and 43° (no elemental Ni peak is detected), confirming that nickel is highly dispersed in an oxidized state. The crystallinity of the support is improved after modification, and there are no impurity peaks, indicating that the high-temperature calcination does not destroy the porous structure, supporting the anti-sintering mechanism of "strong metal-support interaction".

[0121] Attachment Figure 2 The UV-visible light absorption properties of the nickel-based red mud materials obtained in Example 1 (1% Ni) and Example 2 (5% Ni) were compared. The modified nickel-based red mud material exhibited significantly enhanced absorbance in the visible to infrared region (>400 nm), with a particularly broad absorption band appearing in the near-infrared region. This indicates that red mud carrier modification and nickel loading significantly enhance the material's photothermal conversion capacity, providing a sufficient basis for light energy capture in the concentrated photocatalytic DRM reaction.

[0122] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing nickel-based red mud material, characterized in that: The method comprises the following preparation steps: S1. Red mud carrier pretreatment: S11. According to parts by mass, 7-10 parts of red mud powder were added to 500-600 parts of the modified modifier, ultrasonically dispersed at a frequency of 40 kHz for 20-30 min, allowed to stand overnight, the supernatant was discarded, and the solid was separated by centrifugation; S12. The solid separated in step S11 is placed in an oven and dried for 8-12h, then taken out and ground into a fine powder; S13. The powder was ground into a fine powder and passed through an 80-mesh sieve and placed in a muffle furnace. The temperature was slowly raised to 700-900 ° C and calcined in an air atmosphere for 2-4 h. The modified red mud carrier was obtained by cooling; S2 0.05-1 parts of nickel nitrate hexahydrate is dissolved in 30-50 parts of the modified dispersant and stirred for 10-20min until clear to obtain a modified nickel salt solution; S3. Take 0.5-1 parts of the modified red mud carrier and slowly add it to the modified nickel salt solution, magnetically stir at a speed of 300-500r / min for 5-10min, and then ultrasonically disperse for 30-60min to form a suspension; S4. The suspension was transferred to an oil bath, heated for 10-12 hours, stirred continuously until the water evaporated, cooled naturally to room temperature, and then ground. The ground solid product was placed in a muffle furnace, heated to 400-600°C at 2-5°C / min, and calcined in air for 2-4 hours to obtain a nickel-based red mud material. The preparation of the modified modifier comprises the following steps: S111. In parts by mass, 500-600 parts of deionized water were added, 10-15 parts of concentrated nitric acid and 5-8 parts of citric acid, and stirred at a speed of 300-400 r / min in a water bath at 60 ° C for 5-10min to obtain an acidic etching solution; S112 was added to the acidic etching solution 10-15 parts of a surface modifier, ultrasonic dispersion at a frequency of 40kHz for 15-20min to obtain a preliminary modified modifier; S113. Aqueous ammonia was added to the preliminary modified modifier to adjust the pH to 3.8-4.2, and then 45-50 parts of isopropanol were added. The mixture was stirred at a constant temperature of 45 ° C and a speed of 300-400 r / min for 20-30 min, and the modified modifier was obtained by filtration; The preparation of the surface modifier comprises the following steps: S1121. According to parts by mass, 2-5 parts of trisodium citrate were added to 300-400 parts of deionized water, and stirred at a speed of 300-400r / min in a water bath at 60°C until completely dissolved; S1122. To the solution obtained in step S1121, 1.5-3 parts of hexadecyltrimethylammonium bromide and 0.8-1.5 parts of disodium ethylenediaminetetraacetate were added, and ultrasonic dispersion was performed at 45°C for 15-20 minutes to obtain a preliminary modified solution; S1123. Add 3-5 parts of KH-550 to the preliminary modified solution and stir at a speed of 450-500 r / min for 20-30 min to form a milky white emulsion; S1124. To the milky white emulsion, 0.5-1 parts of polyethylene glycol-6000 and 80-100 parts of isopropanol were added and stirred at a constant temperature of 40°C for 10-15 minutes to obtain a surface modifier. The preparation of the modified dispersant comprises the following steps: S21. In parts by mass, 20-25 parts of acetylacetone and 90-100 parts of ethylene glycol were mixed and stirred at 300-400 r / min at 40 ° C for 8-10 min; S22. To the solution obtained in step S21, 8-10 parts of polyethylene glycol-4000 and 0.1-0.5 parts of cerium nitrate were added and ultrasonically dispersed at a frequency of 40 kHz for 10-15 min to obtain a preliminary dispersion; S23. Tetramethylammonium hydroxide is added to the preliminary dispersion to adjust the pH to 8.2-8.8, thereby obtaining a modified dispersant.

2. The method for preparing a nickel-based red mud material according to claim 1, characterized in that: The rate of slow heating in step S13 is 2-5°C / min.

3. The method for preparing a nickel-based red mud material according to claim 1, characterized in that: The drying temperature in step S12 is 60-80°C.

4. The method for preparing a nickel-based red mud material according to claim 1, characterized in that: The stirring speed in step S2 is 300-400 r / min.

5. The method for preparing a nickel-based red mud material according to claim 1, characterized in that: The heating temperature in step S4 is maintained at 70-100°C.

6. Use of the nickel-based red mud material prepared by the preparation method according to any one of claims 1 to 5 in the photocatalytic conversion of methane and carbon dioxide.

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