Mn-containing catalysts, methods for their preparation and use
By preparing high-entropy oxide catalysts containing Mn, Fe, Co, Cu and Sn, and adding Al as a structural aid to form a single spinel phase structure, the problems of low olefin yield and high-temperature deactivation in alkane catalytic cracking of high-entropy oxides were solved, and efficient production of light olefins was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2025-01-03
- Publication Date
- 2026-07-03
AI Technical Summary
Existing high-entropy oxide catalysts exhibit low olefin yields in alkane catalytic cracking and are prone to deactivation at high temperatures, making it difficult to meet the demand for low-carbon and efficient light olefin production.
A high-entropy oxide catalyst containing Mn, Fe, Co, Cu and Sn was used, with Al added as a structural aid. The catalyst was prepared by ball milling and calcination to form a single spinel phase structure, which increased the specific surface area and improved the catalytic activity.
It significantly improved olefin yield, enhanced the high-temperature stability and catalytic activity of the catalyst, and extended the catalyst life.
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Figure CN122321881A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the technical field of catalysts, specifically to a Mn-containing catalyst, its preparation method, and its applications. Background Technology
[0002] Ethylene and propylene, among other light olefins, are important basic feedstocks in the petrochemical industry. With the increasing demand for light olefins, there is an urgent need to develop diversified synthetic routes. Currently, the main source of low-carbon olefins is the traditional steam cracking process, which suffers from technical problems such as high energy consumption, low olefin yield, and difficulty in adjusting product distribution. Under the dual-carbon context, there is an urgent need to develop more low-carbon and efficient technological routes. Naphtha catalytic cracking is the most promising alternative process. Compared with steam cracking, this technology can significantly improve olefin yield, optimize product distribution, reduce energy consumption and costs, and enhance overall economic efficiency. Therefore, research on light hydrocarbon catalytic cracking technology for increasing ethylene and propylene production is of great significance.
[0003] Molecular sieves and metal oxides are two commonly used types of catalytic cracking catalysts. Molecular sieves utilize Brønsted acid sites as their active sites, following a carbocation mechanism. The high Brønsted acid activity of molecular sieves can significantly reduce the catalytic cracking reaction temperature. Currently, fluidized bed naphtha catalytic cracking technology using naphtha as feedstock has been industrialized, with reaction temperatures of 600-700 °C and diene yields reaching 50%. However, a drawback of molecular sieves is severe deactivation due to carbon deposition at high temperatures, making them suitable for low-temperature propylene-rich production routes. Metal oxides utilize surface lattice oxygen to catalyze alkane activation, following a free radical mechanism. They have lower activity, require higher reaction temperatures, and produce ethylene-rich products. Their main advantages are high mechanical strength, resistance to high-temperature moisture, and low carbon deposition. However, the loss of lattice oxygen during the reaction leads to catalyst deactivation.
[0004] High-entropy oxides are emerging multi-cation solid solutions composed of five or more metallic elements. Their formation principle involves providing kinetic energy to the cations at high temperatures, causing them to mix at the atomic level and form a single-phase solid solution with a crystalline structure, followed by rapid quenching to maintain the structure. This atomic-level mixing state makes it difficult for homogeneous elements to agglomerate and phase separation to occur, ensuring the material's high-temperature structural stability. Due to the different valence states and radii of the various metal cations, lattice distortion is easily induced, resulting in a high lattice oxygen concentration and multiple cation active sites. Ultimately, this achieves a synergistic catalytic effect greater than the sum of its parts (1+1>2). High-entropy materials exhibit excellent activity and stability in multiple reactions, significantly extending catalyst lifetime. Utilizing the high lattice oxygen concentration, multiple active sites, and high-temperature structural stability of high-entropy oxides holds promise for solving the technical challenge of simultaneously improving the catalytic activity and stability of metal oxides. However, the overall activity of current high-entropy oxides needs further improvement, especially in increasing olefin yields through alkane catalytic cracking. Summary of the Invention
[0005] The purpose of this invention is to overcome the problems existing in the prior art and to provide a Mn-containing catalyst, its preparation method, and its application.
[0006] To achieve the above objectives, the first aspect of the present invention provides a Mn-containing catalyst, which contains an active component and a structural promoter, wherein the active component is Mn, Fe, Co, Cu and Sn, and the structural promoter is Al, wherein the molar ratio of the active component to the structural promoter is 0.5-2.
[0007] A second aspect of the present invention provides a method for preparing a Mn-containing catalyst, the method comprising: (1) The active component precursor, aluminum source and optional template agent are ball-milled, wherein the active component precursor is a precursor of Mn, Fe, Co, Cu and Sn, and the molar ratio of the active component precursor to the aluminum source is 0.5-2 based on the metal element. (2) The obtained powder is roasted.
[0008] A third aspect of the present invention provides a catalyst prepared by the preparation method of the second aspect of the present invention.
[0009] The fourth aspect of this invention provides the application of the catalyst described in the first aspect, the catalyst prepared by the method described in the second aspect, or the catalyst described in the third aspect in the catalytic cracking of alkane to olefins.
[0010] Through the above technical solution, the present invention has at least the following beneficial effects: (1) The present invention ensures the structural stability of the material by inducing the active metal cations to form a single spinel crystal phase structure by adding the structural aid Al; and increases the specific surface area of the material by adding the template agent to coordinate with the active component precursor salt to create a pore structure.
[0011] (2) The preparation method of the present invention is simple. The active precursor, aluminum source and template agent can be ball-milled and calcined to obtain a catalyst with excellent performance.
[0012] (3) The Mn-containing catalyst prepared in this invention significantly improves the olefin yield in alkane catalytic cracking reaction compared with traditional steam cracking under the same conditions. Attached Figure Description
[0013] Figure 1 This is an X-ray diffraction (XRD) characterization pattern of the catalyst in Example 1; Figure 2 This is the isothermal adsorption-desorption (BET) curve of the catalyst in Example 1. Detailed Implementation
[0014] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0015] The first aspect of the present invention provides a Mn-containing catalyst, characterized in that the catalyst contains an active component and a structural promoter, wherein the active component is Mn, Fe, Co, Cu and Sn, and the structural promoter is Al, wherein the molar ratio of the active component to the structural promoter is 0.5-2.
[0016] Preferably, the molar ratio of the active component to the structural auxiliary is 0.6-1.2, for example, it can be 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, or any range of two of the above values.
[0017] This invention ensures the structural stability of the material by inducing the active component to form a single spinel phase structure through the addition of a structural aid. Therefore, preferably, the catalyst has a single spinel phase structure, which can be characterized by XRD.
[0018] According to the present invention, the molar content of Mn, Fe, Co, Cu, and Sn as a molar percentage of the total active components is independently 10-30%, for example, it can be 10%, 15%, 20%, 25%, 30%, or any two of the above values, preferably 12-25%; that is, the molar content of Mn as a molar percentage of the total active components is 10%-30%, preferably 12%-25%, the molar content of Fe as a molar percentage of the total active components is 10%-30%, preferably 12%-25%, and so on and may be the same or different.
[0019] According to the present invention, the catalyst has the structural formula: Al2(MnFeCoCuSn)O 4-x , where x represents the number of oxygen vacancies, 0 < x ≤ 4.
[0020] According to a preferred embodiment of the present invention, the catalyst is a high-entropy oxide.
[0021] According to a preferred embodiment of the present invention, the catalyst has a specific surface area of not less than 100 m². 2 / g, more preferably not less than 115 m 2 / g, the optimal value is 115-120m 2 / g.
[0022] A second aspect of the present invention provides a method for preparing a Mn-containing catalyst, characterized in that the method comprises: (1) The active component precursor, aluminum source and optional template agent are ball-milled, wherein the active component precursor is a precursor of Mn, Fe, Co, Cu and Sn, and the molar ratio of the active component precursor to the aluminum source is 0.5-2 based on the metal element. (2) The obtained powder is roasted.
[0023] In this invention, the active component precursor can be a substance commonly found in the art that can provide Mn, Fe, Co, Cu and Sn. Preferably, the active component precursor is a Mn salt, Fe salt, Co salt, Cu salt and Sn salt.
[0024] More preferably, the active component precursor is at least one selected from chloride, sulfate and acetate.
[0025] More preferably, the precursor of the active component is MnCl2, FeCl2, CoCl2, CuCl2 and SnCl2.
[0026] In this invention, the aluminum source can be any substance commonly used in the art that can provide Al, as long as it can achieve the purpose of this invention. Preferably, the aluminum source is at least one of aluminum isopropoxide, aluminum acetate, and aluminum propionate, and more preferably aluminum isopropoxide.
[0027] Preferably, the molar ratio of the active component precursor to the aluminum source is 0.6-1.2, calculated by metal element.
[0028] In this invention, the molar content of Mn, Fe, Co, Cu and Sn in the active component precursor each independently accounts for 10%-30% of the total molar content of Mn, Fe, Co, Cu and Sn, preferably 15%-25%.
[0029] In a preferred embodiment, the template agent is at least one of polyethylene glycol, polyethylene diamine, and polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer.
[0030] The specific surface area of the catalyst can be further increased by selecting and adding a template agent, thereby improving the catalytic activity of the catalyst.
[0031] Preferably, the template agent is polyethylene glycol.
[0032] Preferably, the template agent has a weight-average molecular weight of 2000-20000, more preferably 2000-6000.
[0033] Preferably, the ratio of the molar number of the template agent to the total molar number of the active component precursor is 0.05-5, more preferably 0.1-0.5.
[0034] In a specific implementation, in step (1), the ball milling is carried out in a ball mill, which can be one of a planetary ball mill, a vibratory ball mill, a stirred ball mill, or a drum ball mill.
[0035] In a specific embodiment, in step (1), the active component precursor, aluminum source and optional template agent are mixed in a ball milling jar and then fed into a ball mill for ball milling. The ball milling jar can be one of agate ball milling jar, zirconia ball milling jar, stainless steel ball milling jar and corundum ball milling jar.
[0036] In a specific implementation, the ball milling conditions in step (1) include: a ball milling speed of 200-400 r / min, preferably 300-400 r / min; and a ball milling time of 5-30 h, preferably 10-20 h.
[0037] In a specific embodiment, in step (1), the number of grinding balls is preferably 50-100 relative to 50 g of material to be milled. The cross-sectional diameter of the grinding balls is preferably 3-10 mm. Preferably, the ratio of grinding balls with a cross-sectional diameter greater than or equal to 5 mm to grinding balls with a cross-sectional diameter less than 5 mm is 0.5-1.5.
[0038] In a specific implementation, in step (1), the ball milling method is alternating forward and reverse ball milling, and the alternation switching time is 2-30 min, preferably 5-15 min.
[0039] In a specific implementation, the calcination conditions in step (2) include: a calcination temperature of 600-1000℃, preferably 800-900℃; a calcination time of 5-20 h, preferably 8-16 h. The calcination time refers to the time maintained at the above-mentioned calcination temperature. The heating rate during calcination can be 2-20℃ / min.
[0040] A third aspect of the present invention provides a catalyst prepared by the preparation method of the second aspect of the present invention.
[0041] The fourth aspect of this invention provides the application of the catalyst described in the first aspect, the catalyst prepared by the method described in the second aspect, or the catalyst described in the third aspect in the catalytic cracking of alkane to olefins.
[0042] The alkane can be a common alkane used for cracking to produce olefins; in this specific embodiment, the alkane is n-hexane. Correspondingly, when n-hexane is used as the cracking feedstock, the olefins obtained are mainly ethylene, propylene, and butadiene.
[0043] In a further embodiment, the reaction conditions include: a reaction temperature of 600-840°C, a reaction time of at least 1 h, and a weight hourly space velocity (WHSV) of 1-10 h⁻¹ for the alkane. -1 The weight ratio of water to alkanes is 0.5-5.
[0044] The present invention will be described in detail below through embodiments. It should be understood that the following embodiments are only used to further explain and illustrate the content of the present invention, and are not intended to limit the present invention.
[0045] Unless otherwise specified, all reagents and materials used in the following examples were purchased from reputable chemical reagent suppliers and were of analytical purity.
[0046] Example 1 Weigh out 4.73 g of five precursors (excluding water of crystallization) in equimolar ratio: CoCl2, CuCl2, FeCl2, MnCl2, and SnCl2, and place them in a 100 mL ball mill jar. Then weigh out 3.42 g of aluminum isopropoxide and 6.9 g of polyethylene glycol solid with a weight average molecular weight of 4000 and add them to the ball mill jar. Add 50 agate balls with a diameter of 6 mm and 50 agate balls with a diameter of 3 mm.
[0047] After sealing the ball mill jar, it was placed in a planetary ball mill for high-energy ball milling. The milling mode was alternating between forward and reverse rotation, alternating every 15 minutes, at a rotation speed of 400 r / min, for a total milling time of 10 h. The obtained powder was then placed in a muffle furnace for high-temperature calcination, increasing the temperature by 2 °C / min to 600 °C and maintaining it for 5 h. The calcined powder was placed in a Buchner funnel, repeatedly washed with anhydrous ethanol and deionized water, and finally dried in an 80 °C oven to obtain the Mn-containing catalyst. The catalytic cracking performance of the obtained catalyst was evaluated by n-hexane catalytic cracking. The evaluation method involved weighing 20 g of catalyst and loading it into a small-scale catalytic cracking reaction tube (with ceramic balls filling the top and bottom of the catalyst). The reaction tube was then sealed, and heated to a reaction temperature of 650 °C under N2 purging. After 1 h, n-hexane was introduced into the reaction tube. The weight ratio of water to alkane was 1:1, and the weight hourly space velocity (WHSV) was 5 h⁻¹. -1 The reaction was carried out at atmospheric pressure. After 1 hour of reaction, the gaseous and liquid products were collected separately, and the reaction yield was calculated by chromatographic analysis. The results are shown in Table 1.
[0048] Example 2 Same as Example 1, except that the reaction temperature during performance evaluation is 700°C.
[0049] Example 3 Same as Example 1, except that the reaction temperature during performance evaluation is 750°C.
[0050] Example 4 Same as Example 1, except that the reaction temperature for performance evaluation was 750°C and the reaction time was 8 hours.
[0051] Example 5 Same as Example 1, except that the weight-average molecular weight of the polyethylene glycol used is 10,000.
[0052] Comparative Example 1 The catalyst was prepared and its performance evaluated according to the method of Example 1, except that no template agent was added.
[0053] Comparative Example 2 The catalyst was prepared and its performance evaluated according to the method in Example 1, except that aluminum isopropoxide was not added.
[0054] Comparative Example 3 The catalytic cracking test tube was filled with ceramic balls, then sealed. The tube was heated to 750°C under N2 conditions. After 1 hour, n-hexane was introduced into the tube. The weight ratio of water to alkane was 1:1, and the weight hourly space velocity (WHSV) was 5 h⁻¹. -1 The reaction was carried out at atmospheric pressure. The gaseous and liquid products were collected separately, and the reaction yield was calculated. The results are shown in Table 1.
[0055] Comparative Example 4 The catalyst was prepared and its performance evaluated according to the method of Example 1, except that the catalyst was calcined at 600°C.
[0056] Table 1
[0057] Test example: The crystal structure of the catalyst obtained in Example 1 was tested by X-ray diffraction, and the results are as follows: Figure 1 As shown.
[0058] The specific surface area of the catalyst obtained in Example 1 was tested using a physical adsorption method, and the results are as follows: Figure 2 As shown in Table 2.
[0059] The elemental composition of the catalyst obtained in Example 1 was tested using X-ray fluorescence spectroscopy, and the results are shown in Table 3.
[0060] Table 2
[0061] Table 3
[0062] Depend on Figure 1 It can be seen that the catalyst obtained in Example 1 has a single spinel phase structure. Figure 2It can be seen that the isothermal adsorption-desorption curve of the catalyst obtained in Example 1 exhibits a hysteresis loop, indicating that the catalyst has a porous structure. Table 2 shows that the specific surface area of the catalyst prepared in Example 1 is greater than that of the catalyst without the added template agent.
[0063] Table 1 shows that for the prepared catalyst, the yield of trienes continuously increases with increasing reaction temperature. The yield of trienes is lower when the template agent polyethylene glycol or the structural aid aluminum isopropoxide is not added. This catalyst exhibits high-temperature stability and still maintains high catalytic activity after 8 hours of reaction.
[0064] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.
Claims
1. A Mn-containing catalyst, characterized in that, The catalyst contains an active component and a structural aid, wherein the active component is Mn, Fe, Co, Cu and Sn, and the structural aid is Al, wherein the molar ratio of the active component to the structural aid is 0.5-2.
2. The catalyst according to claim 1, wherein, The molar ratio of the active component to the structural additive is 0.6-1.2; And / or, the molar percentage of Mn, Fe, Co, Cu, and Sn in the total active components is independently 10-30%, preferably 12-25%; And / or, the catalyst has the structural formula: Al2(MnFeCoCuSn)O 4-x Where x represents the number of oxygen vacancies, 0 < x ≤ 4; And / or, the catalyst has a spinel structure; And / or, the catalyst is a high-entropy oxide.
3. The catalyst according to claim 1, wherein, The specific surface area of the catalyst is not less than 100 m². 2 / g, preferably not less than 115m 2 / g.
4. A method for preparing an Mn-containing catalyst, characterized in that, The method includes: (1) The active component precursor, aluminum source and optional template agent are ball-milled, wherein the active component precursor is a precursor of Mn, Fe, Co, Cu and Sn, and the molar ratio of the active component precursor to the aluminum source is 0.5-2 based on the metal element. (2) The obtained powder is roasted.
5. The method according to claim 4, wherein, The precursor of the active component is a Mn salt, Fe salt, Co salt, Cu salt, and Sn salt, preferably MnCl2, FeCl2, CoCl2, CuCl2, and SnCl2; And / or, the aluminum source is at least one of aluminum isopropoxide, aluminum acetate, and aluminum propionate, preferably aluminum isopropoxide.
6. The method according to claim 5, wherein, The molar ratio of the active component precursor to the aluminum source, calculated by metal element, is 0.6-1.
2. And / or, the molar content of Mn, Fe, Co, Cu and Sn in the active component precursor each independently accounts for 10-30% of the total molar content of Mn, Fe, Co, Cu and Sn, preferably 15-25%.
7. The method according to claim 4, wherein, The template agent is at least one of polyethylene glycol, polyethylene diamine, and polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, preferably polyethylene glycol; And / or, the weight-average molecular weight of the template agent is 2000-20000, preferably 2000-6000; And / or, the ratio of the molar number of the template agent to the total molar number of the active component precursor calculated as metal element is 0.05-5, preferably 0.1-0.
5.
8. The method according to claim 4, wherein, In step (1), the ball milling is carried out in a ball mill, which is one of a planetary ball mill, a vibratory ball mill, a stirred ball mill, or a drum ball mill; And / or, the active component precursor, aluminum source and optional template agent are mixed in a ball mill jar and then fed into a ball mill for ball milling, wherein the ball mill jar is one of agate ball mill jar, zirconia ball mill jar, stainless steel ball mill jar and corundum ball mill jar; And / or, the conditions for ball milling include: a ball milling speed of 200-400 r / min, a ball milling time of 5-30 h, a number of 20-100 balls relative to 50 g of material to be milled, and a cross-sectional diameter of 2-12 mm for the balls. Preferably, the ratio of the number of balls with a cross-sectional diameter greater than or equal to 5 mm to the number of balls with a cross-sectional diameter less than 5 mm is 0.5-1.
5. And / or, the ball milling method is alternating forward and reverse ball milling, with an alternation switching time of 2-30 minutes.
9. The method according to claim 4, wherein, In step (2), the calcination conditions include: a calcination temperature of 600-1000 ℃ and a calcination time of 5-20 h.
10. The catalyst prepared by the method according to any one of claims 4-8.
11. The use of the catalyst according to any one of claims 1-3 or claim 10 in the catalytic cracking of alkane to olefins.
12. The application according to claim 11, wherein, The alkane is n-hexane; And / or, the conditions for the catalytic cracking include: a reaction temperature of 600-840°C, a reaction time of at least 1 h, and a weight hourly space velocity (WHSV) of 1-10 h for the alkane. -1 The weight ratio of water to alkanes is 0.5-5.