Preparation method and application of high-entropy alloy catalyst
By preparing high-entropy alloy catalysts through the sol-gel method and Joule heating, the problems of insufficient stability and sulfur resistance of transition metal catalysts in the catalytic oxidation of low-carbon alkanes were solved, achieving low-temperature high-efficiency catalysis and green energy-saving catalytic effects.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHEJIANG UNIV
- Filing Date
- 2025-06-18
- Publication Date
- 2026-05-12
AI Technical Summary
Existing transition metal catalysts lack stability and sulfur resistance in the catalytic oxidation of low-carbon alkanes, making it difficult to efficiently activate and catalytically convert volatile organic compounds at low temperatures.
Catalyst precursor powder was prepared by sol-gel method, and the catalyst precursor in the gap of conductive material was heated by Joule heating. High entropy alloy catalyst was prepared by using Joule heating to generate high temperature, thus avoiding the input of external energy.
It achieves high-efficiency catalytic performance for low-carbon alkanes at low temperatures, exhibits excellent sulfur resistance and stability, and significantly shortens catalyst preparation time and reduces energy consumption.
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Figure CN120861078B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalyst preparation technology, specifically relating to a method for preparing a high-entropy alloy catalyst and its application. Background Technology
[0002] Pollutants emitted during industrial production are the core source of air pollution. While pollutants such as sulfur oxides, nitrogen oxides, and particulate matter emitted from fuel combustion have been effectively controlled, volatile organic compounds (VOCs) remain unreliably treated. In the coal chemical industry, over 50% of VOC emissions are fugitive emissions. Low-temperature methanol wash exhaust contains large amounts of volatile methanol, along with significant amounts of carbonyl sulfide and H2S. VOCs escaping from wastewater treatment ponds mainly consist of over 40 organic compounds in six categories: alkanes, alkenes, halogenated hydrocarbons, aromatic hydrocarbons, alcohols, and sulfides. Among these, low-carbon alkanes, due to their high CH bond energy and chemical stability, are difficult to efficiently activate and catalyze at low temperatures, representing a current research hotspot and challenge.
[0003] Transition metal catalysts are catalysts with transition metal oxides as the main active component, exhibiting good catalytic activity. Transition metal oxide catalysts, such as those containing Co, Mn, Ni, Cr, Fe, Zr, or Ce, have been extensively studied for the catalytic oxidation of light alkanes. However, most existing transition metal catalysts still suffer from instability and insufficient catalytic activity, limiting their application in practical industrial production.
[0004] Therefore, it is essential to develop a high-entropy alloy catalyst with good stability, low catalytic temperature, and good sulfur resistance. Summary of the Invention
[0005] To address at least one of the aforementioned problems, this invention provides a method for preparing a high-entropy alloy catalyst, which exhibits good low-temperature catalytic performance for low-carbon alkanes and excellent sulfur resistance and stability.
[0006] To achieve the above objectives, the present invention employs the following technical means:
[0007] The first aspect of the present invention provides a method for preparing a high-entropy alloy catalyst, comprising the following steps:
[0008] S1. The transition metal salt is uniformly mixed with citric acid solution, and the catalyst precursor powder is prepared by sol-gel method. The catalyst precursor is then heated and dried.
[0009] S2. After the obtained catalyst precursor powder is pressed into tablets under a certain pressure, it is evenly placed in the gap between two layers of conductive material. The two sides of the conductive material are clamped to the two ends of the electrode, and current is passed through. The power is output by a programmable power supply, and the high-entropy alloy catalyst is prepared by utilizing the high temperature generated by Joule heating.
[0010] In some embodiments of the present invention, the transition metal salt includes one of cobalt nitrate, nickel nitrate, manganese nitrate, cerium nitrate, chromium nitrate, zirconium nitrate, and iron nitrate.
[0011] In some embodiments of the present invention, one of cobalt nitrate, nickel nitrate, manganese nitrate, cerium nitrate, chromium nitrate, zirconium nitrate, and ferric nitrate is in a molar ratio of (1-4):(1-4):(1-4):1:1.
[0012] In some embodiments of the present invention, the molar concentration of the citric acid solution is 1-2 times the molar concentration of the metal salt.
[0013] In some embodiments of the present invention, the conductive material is one of carbon felt, carbon paper, foamed metal, and graphite rod.
[0014] In some embodiments of the present invention, the power supply output power is 100-150 W.
[0015] In some embodiments of the present invention, the catalyst precursor powder is added in the gap between the two conductive materials at a single application rate of 0.5-2g.
[0016] In some embodiments of the present invention, in step S1, the heating temperature is 450-650 ℃ and the heating time is 15-60 s.
[0017] A second aspect of the present invention provides a high-entropy alloy catalyst prepared by the method described in the first aspect.
[0018] A third aspect of the present invention provides an application of the high-entropy alloy catalyst described in the second aspect in the low-temperature catalytic degradation of low-carbon alkanes below 300°C.
[0019] In some embodiments of the present invention, the low-carbon alkane is ethane and propane.
[0020] Beneficial effects of the present invention
[0021] Compared with existing technologies, this invention has the following advantages: This invention provides a method for preparing a high-entropy alloy catalyst. The catalyst uses transition metal salts as raw materials, and a catalyst precursor powder is prepared by a sol-gel method with an acid solution. This powder is then placed between two layers of conductive material, and the high-entropy alloy catalyst is prepared using Joule heating at high temperatures. Joule heating offers a fast heating rate, enabling rapid high-temperature treatment of the material, and consumes little energy, significantly shortening the catalyst preparation time. Furthermore, it requires no external energy input, achieving green and energy-saving results. The high-entropy alloy catalyst prepared using this method exhibits good low-temperature catalytic performance for low-carbon alkanes and demonstrates excellent sulfur resistance and stability. Attached Figure Description
[0022] Figure 1 The comparison of the propane catalytic performance of the high-entropy alloy catalysts prepared in Examples 1 and 9 is shown.
[0023] Figure 2 The comparison of the propane catalytic performance of the high-entropy alloy catalysts prepared in Examples 1 to 3 is shown.
[0024] Figure 3 The comparison of the propane catalytic performance of the high-entropy alloy catalysts prepared in Examples 1, 4, and 5 is shown.
[0025] Figure 4 The propane catalytic performance of the high-entropy alloy catalysts prepared in Examples 6 to 8 is compared.
[0026] Figure 5 The comparison of the catalytic performance of the high-entropy alloy catalyst prepared in Example 6 for methane, ethane, and propane is shown.
[0027] Figure 6 The stability test results of the high-entropy alloy catalyst prepared in Example 6 are shown;
[0028] Figure 7 The comparison of the catalytic performance of the high-entropy alloy catalyst prepared in Example 1 on propane under alternating reaction conditions of 250 °C and 350 °C is shown.
[0029] Figure 8 The results of the catalytic performance of the high-entropy alloy catalyst prepared in Example 4 on propane are shown.
[0030] Figure 9 The comparison of the propane catalytic performance of the high-entropy alloy catalyst prepared in Example 6 with that of a commercial palladium-based catalyst is shown.
[0031] Figure 10 The graph shows the temperature changes of the external heat source and the catalyst under the conditions of Joule heating and calcination at 550 °C for 30 s for the high-entropy alloy catalyst of Example 4. Detailed Implementation
[0032] The following examples are used to illustrate preferred embodiments of the invention. Those skilled in the art will understand that the techniques disclosed in the examples represent techniques discovered by the inventors that can be used to implement the invention, and therefore can be considered preferred embodiments for implementing the invention. However, those skilled in the art should understand from this specification that many modifications can be made to the specific embodiments disclosed herein, still yielding the same or similar results, without departing from the spirit or scope of the invention.
[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains, and all materials disclosed herein and cited therein are incorporated herein by reference. Many equivalent techniques of specific embodiments of the invention described herein will be recognized or can be understood by ordinary experimentation by those skilled in the art. These equivalents will be included in the claims.
[0034] The technical solution of this application will be further described in detail below with reference to specific embodiments.
[0035] Example 1
[0036] Cobalt nitrate, nickel nitrate, manganese nitrate, cerium nitrate, and chromium nitrate, transition metal salts, were uniformly mixed with citric acid solution in a molar ratio of 1:1:1:1:1, with the molar concentration of the citric acid solution being twice that of the metal salts. A catalyst precursor was prepared using the sol-gel method. The catalyst precursor powder was obtained by heating at 600 °C for 45 s.
[0037] Two g of the prepared catalyst precursor powder was pressed into tablets under a certain pressure and then evenly placed between two layers of conductive material. The conductive material was then clamped to both ends of the electrode. Current was applied, and a programmable power supply was used to control the input power and calcination time of the conductive material by adjusting the power supply program. High-entropy alloy catalysts were prepared using the high temperature generated by Joule heating. The power supply output power ranged from 100 ohms. The calcination temperature was measured using a short-wave infrared thermometer at 450 °C.
[0038] Example 2
[0039] The method is the same as in Example 1, except that: cobalt nitrate, nickel nitrate, manganese nitrate, cerium nitrate, and ferric nitrate, transition metal salts, are taken in a molar ratio of 1:1:1:1:1 and mixed evenly with citric acid solution.
[0040] Example 3
[0041] The method is the same as in Example 1, except that: cobalt nitrate, nickel nitrate, manganese nitrate, cerium nitrate, and zirconium nitrate, transition metal salts, are taken in a molar ratio of 1:1:1:1:1 and mixed evenly with citric acid solution.
[0042] Example 4
[0043] The method is the same as in Example 1, except that the power output is adjusted to 135 W and a short-wave infrared thermometer is used to measure the calcination temperature, which is 550 °C.
[0044] Example 5
[0045] The method is the same as in Example 1, except that the power output is adjusted to 150 W and a short-wave infrared thermometer is used to measure the calcination temperature, which is 650 °C.
[0046] Example 6
[0047] The method is the same as in Example 1, except that: cobalt nitrate, nickel nitrate, manganese nitrate, cerium nitrate, and chromium nitrate are taken as transition metal salts in a molar ratio of 2.5:1:1:1:1.
[0048] Example 7
[0049] The method is the same as in Example 1, except that: cobalt nitrate, nickel nitrate, manganese nitrate, cerium nitrate, and chromium nitrate are taken as transition metal salts in a molar ratio of 1:2.5:1:1:1.
[0050] Example 8
[0051] The method is the same as in Example 1, except that: cobalt nitrate, nickel nitrate, manganese nitrate, cerium nitrate, and chromium nitrate are taken as transition metal salts in a molar ratio of 1:1:2.5:1:1.
[0052] Example 9
[0053] The method is the same as in Example 1, except that the catalyst is prepared by a conventional calcination method. The obtained catalyst powder is filled into a crucible and calcined at 550 °C for 4 h in an air atmosphere at a heating rate of 5 °C / min to obtain the target catalyst.
[0054] Performance comparison:
[0055] (1) Propane catalytic conversion experiments were conducted using the high-entropy alloy catalysts prepared in Examples 1 and 9. The propane concentration was 2000 ppm, and the carrier gas was air. The propane conversion rates of the catalysts were as follows at reaction temperatures between 150 and 325 °C: Figure 1 As shown.
[0056] The results showed that the high-entropy alloy catalyst prepared by Joule heating had a T90 temperature of 262 ℃, while the catalyst prepared by ordinary calcination method had a T90 temperature of 307 ℃. Under the same conditions, the catalyst prepared by Joule heating had a lower T90 temperature.
[0057] (2) Propane catalytic conversion experiments were conducted using the high-entropy alloy catalysts prepared in Examples 1 to 3. The propane concentration was 2000 ppm, and the carrier gas was air. The propane conversion rates of the catalysts were as follows at reaction temperatures between 150 and 300 °C: Figure 2 As shown.
[0058] The results showed that when chromium nitrate in the transition metal was replaced by zirconium nitrate, the T90 temperature changed from 262 ℃ to 264 ℃, and the catalyst had little effect on the propane conversion rate. When chromium nitrate in the transition metal was replaced by ferric nitrate, the T90 temperature of the catalyst decreased to 293 ℃, and the catalytic efficiency for propane was greatly reduced.
[0059] (3) Propane catalytic conversion experiments were conducted using the high-entropy alloy catalysts prepared in Examples 1, 4, and 5. The propane concentration was 2000 ppm, and the carrier gas was air. The propane conversion rates of the catalysts were obtained at reaction temperatures between 150 and 300 °C as follows: Figure 3 As shown.
[0060] The results showed that the calcination temperature was measured using a short-wave infrared thermometer. The catalyst T90 prepared at a calcination temperature of 550 ℃ had a temperature of 262 ℃, which was lower than that of the catalysts prepared at 450 ℃ and 650 ℃.
[0061] (4) Propane catalytic conversion experiments were conducted using the high-entropy alloy catalysts prepared in Examples 6 to 8. The propane concentration was 2000 ppm, and the carrier gas was air. The propane conversion rates of the catalysts were as follows at reaction temperatures between 150 and 300 °C: Figure 4 As shown.
[0062] The results showed that when the Co content increased, the T90 temperature decreased to 246 ℃, and when the Mn content increased, the T90 temperature decreased to 250 ℃. When the Ni content increased, the T90 temperature did not change significantly. This demonstrates that the catalyst performance can be controlled by adjusting the amount of active metal added. Adjusting the content of Co and Mn can significantly improve the catalytic performance of the catalyst, with Co showing the most significant improvement.
[0063] (5) The degradation performance of different types of short-chain hydrocarbons (methane, ethane, propane) was compared using the high-entropy alloy catalyst prepared in Example 6. The concentration of short-chain hydrocarbons (methane, ethane, propane) was 2000 ppm, and the carrier gas was air. The conversion rates of short-chain hydrocarbons (methane, ethane, propane) of the catalyst were as follows at reaction temperatures between 150-400 °C: Figure 5 As shown.
[0064] The results showed that the high-entropy alloy catalyst exhibited weaker catalytic performance for methane than for ethane and propane. Furthermore, the T90 temperature for the catalytic conversion of propane was 246 °C, while the T90 temperature for the catalytic conversion of ethane was 291 °C. The catalyst's catalytic temperature for propane was lower than that for ethane.
[0065] (6) The stability of the high-entropy alloy catalyst prepared in Example 6 was tested: 2000 ppm propane was introduced at 275 °C, and the catalytic efficiency of the catalyst was recorded during the 30-hour reaction. The results are as follows: Figure 6 As shown.
[0066] The results showed that the catalyst did not decrease in catalytic efficiency and achieved complete degradation of propane during the 30-hour reaction at 275 °C, demonstrating good catalytic stability.
[0067] (7) The high-entropy alloy catalyst prepared in Example 1 was used to react alternately at catalytic temperatures of 250 °C and 350 °C, with each temperature reacting for 10 hours. The catalytic performance on propane was tested, and the results are as follows: Figure 7 As shown.
[0068] The results show that the catalyst exhibits good stability in multiple long-term catalytic temperature-variable experiments, demonstrating good adaptability to complex operating conditions with temperature fluctuations in industrial applications.
[0069] (8) The high-entropy alloy catalyst prepared in Example 4 was tested at 275 °C with 50 ppm SO2 introduced to assess its catalytic performance on propane. The results are as follows: Figure 8 As shown.
[0070] The results showed that at 275 °C, when 50 ppm of SO2 was introduced, the performance of the catalyst decreased by 18% during the 50-hour catalytic reaction, while the catalytic efficiency remained stable at around 82% without any downward trend, demonstrating excellent sulfur resistance.
[0071] (9) A comparison of the propane catalytic performance of the high-entropy alloy catalyst prepared in Example 6 and the commercial palladium-based catalyst is as follows: Figure 9 As shown.
[0072] The results show that the high-entropy alloy catalyst prepared in this application has a T90 temperature of 246 °C for propane catalysis, while the commercial palladium-based catalyst has a T90 temperature of 368 °C for propane catalysis. Compared with the latter, the catalyst prepared in this application has higher catalytic efficiency for propane and a lower catalytic temperature.
[0073] (10) The high-entropy alloy catalyst of Example 4 was prepared by the Joule heating method and calcined at 550 °C for 30 s. The temperature changes of the external heat source and the catalyst are shown in the figure. Figure 10 As shown.
[0074] The results showed that during the heating phase, the catalyst gradually heated up along with the external heat source, exhibiting a significant thermal lag. The heating rate of the external heat source was significantly higher than that of the catalyst, indicating a certain resistance to heat transfer. Heat transfer from the external heat source to the catalyst required a certain amount of time, after which the set calcination temperature could be reached. Once equilibrium was reached, the temperature difference between the catalyst and the external heat source was very small, and heat transfer reached dynamic equilibrium. During the temperature decrease phase, the catalyst temperature also lagged behind the external heat source temperature decrease. Using the Joule heating method to prepare the catalyst, thermal equilibrium between the catalyst and the external heat source could be reached within 30 seconds, significantly shortening the time required for catalyst preparation.
[0075] All documents mentioned in this invention are incorporated herein by reference as if each document were individually incorporated by reference. Furthermore, it should be understood that after reading the foregoing teachings of this invention, those skilled in the art can make various alterations or modifications to this invention, and these equivalent forms also fall within the scope defined by this application.
Claims
1. The application of high-entropy alloy catalysts in the low-temperature catalytic degradation of ethane and propane below 300°C, characterized in that, The preparation of the high-entropy alloy catalyst includes the following steps: S1. The transition metal salt is uniformly mixed with citric acid solution, and the catalyst precursor powder is prepared by sol-gel method. The catalyst precursor is then heated and dried. S2. After the obtained catalyst precursor powder is pressed into tablets under a certain pressure, it is evenly placed in the gap between two layers of conductive material. The two sides of the conductive material are clamped to the two ends of the electrode respectively. Current is passed through and the power is output by a programmable power supply. The high-entropy alloy catalyst is prepared by utilizing the high temperature generated by Joule heating. The transition metal salts include cobalt nitrate, nickel nitrate, manganese nitrate, cerium nitrate, and one selected from chromium nitrate, zirconium nitrate, and ferric nitrate, in a molar ratio of (1-4):(1-4):(1-4):1:
1.
2. The application of the high-entropy alloy catalyst according to claim 1 in the low-temperature catalytic degradation of ethane and propane below 300°C, characterized in that: The molar concentration of the citric acid solution is 1-2 times that of the metal salt.
3. The application of the high-entropy alloy catalyst according to claim 1 in the low-temperature catalytic degradation of ethane and propane below 300°C, characterized in that: The conductive material is one of carbon felt, carbon paper, foamed metal, and graphite rod.
4. The application of the high-entropy alloy catalyst according to claim 1 in the low-temperature catalytic degradation of ethane and propane below 300°C, characterized in that: The power supply output power is 100-150 W.
5. The application of the high-entropy alloy catalyst according to claim 1 in the low-temperature catalytic degradation of ethane and propane below 300°C, characterized in that: The amount of catalyst precursor powder added into the gap between the two conductive materials is 0.5-2 g per application.
6. The application of the high-entropy alloy catalyst according to claim 1 in the low-temperature catalytic degradation of ethane and propane below 300°C, characterized in that: In step S1, the heating temperature is 450-650 ℃, and the heating time is 15-60 s.