Preparation method and application of ordered mesoporous composite oxide carrier
By preparing ordered mesoporous composite oxide supports, the problem of structural collapse of mesoporous alumina at high temperatures was solved, achieving low-temperature activity and long lifespan performance of highly efficient ammonia decomposition hydrogen production catalysts, and improving the energy efficiency of hydrogen energy.
Patent Information
- Application Number
- CN202511510127.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-22
- Publication Date
- 2026-01-30
AI Technical Summary
Existing technologies struggle to maintain the structural stability and specific surface area of mesoporous alumina supports at high temperatures, leading to catalyst deactivation in ammonia decomposition for hydrogen production and impacting the efficiency of hydrogen energy utilization.
An ordered mesoporous composite oxide support was prepared by solvent evaporation-induced self-assembly combined with segmented calcination. By introducing alkaline earth metals and rare earth metals, a composite oxide support with high specific surface area and thermal stability was formed, and active metals and additives were loaded.
This achieved stability of the bulk structure and dispersion of active metals at high temperatures, significantly reduced the ammonia decomposition reaction temperature, improved the low-temperature activity and long-term stability of the catalyst, and enhanced the energy efficiency of hydrogen energy.
Smart Images
Figure CN121422951A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of inorganic functional materials and heterogeneous catalysis, and particularly to a preparation method and application of an ordered mesoporous composite oxide carrier. BACKGROUND
[0002] With the increasing demand for energy and the increasing requirements for environmental protection, the development and utilization of new clean energy are attracting more and more attention. Among them, hydrogen energy as a secondary energy has the advantages of clean and environmental protection, and its development is highly valued. Hydrogen can be directly burned to provide energy, or can be used to generate electricity through hydrogen fuel cells, and there is no emission of pollutants such as COx and NOx during use, so it is very clean and environmentally friendly. However, hydrogen has low volumetric energy density, high storage cost, and low transportation efficiency. It is highly expected to use hydrogen storage carriers that are relatively easy to store and transport for efficient transportation and storage, and the corresponding technology development is of great significance.
[0003] There are many types of hydrogen storage carriers currently being studied. Among them, ammonia is considered one of the ideal hydrogen storage carriers due to its high hydrogen storage density, easy liquefaction, mature transportation technology, low hydrogen production cost, and no COx generation during decomposition. The ammonia decomposition reaction equation is as follows:
[0004] ,
[0005] Theoretically, the equilibrium conversion rate of this reaction can reach 99% at 400°C, but it actually needs to be higher than 1000°C to occur, and the presence of a catalyst helps to reduce the ammonia decomposition reaction temperature, but generally still needs to be higher than 650°C. High-temperature operation requires high utility conditions, high energy consumption, and large energy loss, which seriously affects the efficiency of hydrogen energy use. Therefore, developing high-efficiency catalysts to reduce the ammonia decomposition reaction temperature helps to improve the hydrogen energy efficiency of the ammonia hydrogen carrier process, and plays a crucial role in the industrial application and promotion of ammonia hydrogen carrier.
[0006] In ammonia decomposition catalysts, the performance of active metals such as Ni, Co, and Ru largely depends on their carriers. An ideal carrier should have a high specific surface area to disperse and stabilize the active metal, and at the same time have excellent structural stability under high-temperature reaction conditions. Alumina (Al2O3) is widely used as a catalyst carrier due to its high specific surface area and good mechanical strength. However, pure alumina will undergo phase transformation and sintering at temperatures higher than 800°C, resulting in a sharp decrease in specific surface area, collapse of pore structure, and aggregation of the supported active metal, leading to rapid degradation of catalyst performance.
[0007] Although mesoporous alumina material can provide higher specific surface area and regular channels, its thermal stability problem is more prominent. The traditional preparation method is difficult to obtain ordered mesoporous structure while giving it the ability to resist sintering at high temperature usually > 600 ℃ required for ammonia decomposition and long-term operation.
[0008] Therefore, developing a composite oxide carrier that can withstand high temperature heat treatment and reaction conditions while maintaining high specific surface area and ordered mesoporous structure is a key prerequisite and technical difficulty for obtaining high-performance, long-life ammonia decomposition hydrogen production catalyst.
[0009] To this end, the present application provides a preparation method and application of an ordered mesoporous composite oxide carrier to solve the problems raised in the above background. SUMMARY
[0010] In view of the deficiencies of the prior art, the present application provides a preparation method and application of an ordered mesoporous composite oxide carrier to solve the problems raised in the above background.
[0011] To achieve the above object, the present application is realized by the following technical scheme:
[0012] On the one hand, the present application provides a preparation method of an ordered mesoporous composite oxide carrier, characterized in that the method comprises the following steps:
[0013] (1) Dissolve the template agent polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer P123 in anhydrous ethanol to form an alcohol solution; then add dilute nitric acid, and then add aluminum isopropoxide, alkali earth metal soluble salt and rare earth metal soluble salt to the above solution, and after dissolution, a mixed solution is obtained;
[0014] (2) The mixed solution obtained in step (1) is subjected to solvent evaporation induced self-assembly at 40-100℃, preferably 50-70℃ for 10-60 hours, preferably 15-35 h, to obtain a xerogel;
[0015] (3) The xerogel obtained in step (2) is subjected to staged calcination: first, under an inert atmosphere, the temperature is raised to 200-600℃ at a rate of 0.5-10℃ / min, and kept constant for 1-10 hours, preferably the temperature is raised to 350-450℃ at a rate of 1-3℃ / min, and kept constant for 2-5 h; then in an oxygen and inert gas mixture atmosphere with an oxygen concentration of 0.1-5%, preferably 0.3-1%, the temperature is raised to 1000℃ at a rate of 0.5-10℃ / min, and kept constant for 3 hours, preferably the calcination temperature is increased to 1000℃ at a rate of 1-5℃ / min, and kept constant for 3 h; to obtain the ordered mesoporous composite oxide carrier;
[0016] Specifically, based on the weight of the ordered mesoporous composite oxide carrier, and calculated as metal oxides, the content of alkaline earth metal oxides is 5-20%, preferably 8-15%; the content of rare earth metal oxides is 2-15%, preferably 5-10%; and the remainder is... .
[0017] The alkaline earth metal oxide is one or more of CaO, MgO, BaO, and SrO, more preferably one or more of MgO and CaO; the rare earth metal oxide is... , , , and One or more of them, further preferably , or One or more of them.
[0018] In step (1), the molar ratio of the template agent P123 to the total metal ions is 0.8~3, preferably 1~2; the amount of anhydrous ethanol used is such that the concentration of the template agent in the resulting alcohol solution is 0.001~0.04 mol / L, preferably 0.005~0.02 mol / L.
[0019] In step (3), the inert atmosphere for the first stage of roasting is nitrogen, and the gas linear velocity is 10~30 mm / s; during the second stage of roasting, the oxygen concentration in the mixed atmosphere is controlled to be 0.3~1%.
[0020] An ordered mesoporous composite oxide support prepared by the above method, after being calcined at 1000℃ for 3 hours, has a pore volume of 0.2~0.9 cm³ / g, preferably 0.5~0.8 cm³ / g; a specific surface area of 200~400 m² / g, preferably 250~350 m² / g; and an average pore size of 5~15 nm, preferably 8~12 nm.
[0021] On the other hand, the present invention provides an application of an ordered mesoporous composite oxide support in the preparation of ammonia decomposition hydrogen production catalysts:
[0022] The catalyst is prepared by loading an active metal and an auxiliary agent onto an ordered mesoporous composite oxide support; the active metal is selected from one or more compounds of Ni and Co; the auxiliary agent is selected from one or more compounds of Mo and W; based on the total mass of the ammonia decomposition hydrogen production catalyst, the content of the active metal component, calculated as oxide, is 5-20%, preferably 10-18%, the content of the auxiliary agent is 1-5%, preferably 2-4%, and the balance is the ordered mesoporous composite oxide support.
[0023] The preparation method of the ammonia decomposition hydrogen production catalyst includes: impregnating an ordered mesoporous composite oxide support with an impregnation solution containing an active metal and an auxiliary metal using a stepwise impregnation method, followed by drying and calcination.
[0024] The drying temperature is 80~140℃, preferably 100~130℃, and the time is 1~10 hours, preferably 2~5 hours; the roasting is segmented roasting, the roasting temperature after the first impregnation is 200~500℃, preferably 280~400℃, and the time is 1~8 hours, preferably 2~4 hours; the roasting temperature after the second impregnation is 300~700℃, preferably 400~550℃, and the time is 1~10 hours, preferably 2~4 hours.
[0025] The method for producing hydrogen through ammonia decomposition catalyst includes: using an ammonia decomposition catalyst, at a reaction temperature of 450~750℃, preferably 500~650℃, a pressure of 0~5 MPa, preferably 1~3 MPa, and a feed gas space velocity of 2000~10000. Preferably 3000~6000 Under certain conditions, ammonia gas is brought into contact with a catalyst to react.
[0026] This invention provides a method for preparing an ordered mesoporous composite oxide support and its application. It has the following beneficial effects:
[0027] 1. Stable carrier structure and excellent anti-sintering performance: This invention successfully prepares a composite oxide carrier with a highly ordered mesoporous structure by combining a special solvent evaporation-induced self-assembly with a two-step controlled atmosphere calcination process. This carrier can withstand high-temperature heat treatment at 1000℃ and above, and its mesoporous structure is not easily collapsed. It has a high specific surface area and pore volume retention rate, exhibiting extremely excellent thermal stability and anti-sintering ability, fundamentally solving the problem of easy deactivation of traditional mesoporous materials at high temperatures.
[0028] 2. High catalyst activity at low temperatures and improved reaction efficiency: Due to the regular pore structure and optimized surface chemistry of the support, it provides an ideal platform for the high dispersion of active metals. After loading the active component, the interaction between the active metal and the support is effectively modulated, making the catalyst easier to reduce and activate. This significantly reduces the activation temperature and activation energy of the ammonia decomposition reaction, achieving a high ammonia conversion rate at relatively low temperatures and effectively reducing energy consumption.
[0029] 3. Long catalyst life and good stability: The excellent high-temperature stability of the support lays the foundation for the catalyst to maintain its performance during long-term high-temperature operation. At the same time, the alkaline earth metal and rare earth metal components introduced into the support further stabilize the support structure and inhibit the migration and sintering of active metals, enabling the catalyst to maintain high activity and structural integrity under harsh reaction conditions, exhibiting excellent long-term operational stability.
[0030] 4. Flexible composition and process design, with strong versatility: The composition and preparation method of the ordered mesoporous composite oxide support of this invention offer a wide range of adjustability, allowing for flexible selection of metal types and ratios according to different needs. This method is not only applicable to the preparation of composite supports with multiple element combinations, but also provides a universal and reliable platform for loading different types of active metals, showing good prospects for industrial application. Attached Figure Description
[0031] Figure 1 These are TEM images of the ordered mesoporous composite oxide supports obtained in Example 1 and Comparative Example 1.
[0032] Figure 2 These are the H2-TPR spectra of the ammonia decomposition hydrogen production catalysts obtained in Example 1 and Comparative Example 2;
[0033] Figure 3 This is the long-term stability evaluation result of the ammonia decomposition hydrogen production catalyst obtained in Example 1. Detailed Implementation
[0034] To enable those skilled in the art to understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.
[0035] The present invention will now be described in detail with reference to the accompanying drawings:
[0036] Example 1 (refer to) Figure 1 , Figure 2 and Figure 3 This embodiment provides a method for preparing and applying an ordered mesoporous composite oxide support. The specific implementation method is as follows:
[0037] (1) Preparation of an ordered mesoporous composite oxide support
[0038] 42 g of surfactant P123 was weighed and dissolved in 800 ml of anhydrous ethanol. After complete dissolution at room temperature, 64 ml of concentrated nitric acid was added dropwise. After thorough stirring, 81.6 g of aluminum isopropoxide was added. After complete dissolution, 38.2 g of magnesium nitrate and 10.6 g of lanthanum nitrate were added. After stirring and dissolving, the sample was placed in an oven and dried at 60 °C for 30 h. The dried sample was then placed in a muffle furnace and calcined at 400 °C for 4 h under a nitrogen flow rate of 20 mm / s and a heating rate of 1 °C / min. The temperature was then further increased to 1000 °C and calcined for 3 h at a heating rate of 2 °C / min. The resulting support was denoted as [missing information]. Its TEM image is shown Figure 1 The pore striations of the mesoporous material are clearly visible in the figure, indicating that even after calcination at 1000℃, the carrier still maintains a regular and ordered mesoporous pore structure. Its physical properties are shown in Table 1, and the data in the table show that the carrier has a large specific surface area.
[0039] (2) Application of an ordered mesoporous composite oxide support in the preparation of ammonia decomposition hydrogen production catalyst
[0040] Weigh out 7.13 g and 0.42 g Dissolve the sample in 10 mL of deionized water and stir until dissolved. Pour the solution onto 10 g of the prepared ordered mesoporous composite oxide support and shake thoroughly to ensure uniform impregnation. Then, dry the sample in an oven at 120 °C for 4 h. Next, place the sample in a muffle furnace and heat it to 300 °C at a rate of 3 °C / min. Hold the temperature for 3 h and impregnate it again. The second calcination temperature is 500 °C, thus obtaining the ammonia decomposition hydrogen production catalyst.
[0041] The H2-TPR spectrum of the ammonia decomposition hydrogen production catalyst obtained in this embodiment is shown in the figure. Figure 2 middle.
[0042] (3) Activity evaluation of ammonia decomposition to hydrogen production catalyst
[0043] 1 g of the ammonia decomposition hydrogen production catalyst obtained in this example was weighed and loaded into a fixed-bed reactor. Activation was performed by reduction at 500°C for 3 hours under a pure hydrogen atmosphere at atmospheric pressure. After reduction, the temperature was raised to 550°C under a hydrogen atmosphere, and the feed gas was switched for reaction. The reaction space velocity was 6000 h⁻¹. -1 The reaction pressure was 2 MPa. Online gas chromatography analysis of the tail gas composition yielded an ammonia conversion rate of 83.6%. This demonstrates that the catalyst exhibits high low-temperature activity, significantly superior to the domestically produced reference catalyst. Furthermore, to investigate the long-term reaction stability of the ammonia decomposition to hydrogen catalyst, a long-term reaction performance evaluation was conducted, and the results are shown below. Figure 3 As can be seen from the figure, this catalyst exhibits excellent high-temperature thermal stability.
[0044] Example 2 provides a method for preparing and applying an ordered mesoporous composite oxide support. The specific implementation is as follows:
[0045] (1) Preparation of an ordered mesoporous composite oxide support
[0046] 56 g of surfactant P123 was weighed and dissolved in 800 ml of anhydrous ethanol. After complete dissolution at room temperature, 64 ml of concentrated nitric acid was added dropwise, and after thorough stirring, 81.6 g of aluminum isopropoxide was added. After complete dissolution, 25.4 g of magnesium nitrate and 13 g of lanthanum nitrate were added. After stirring and dissolving, the sample was placed in an oven and dried at 70 °C for 20 h. The dried sample was then placed in a muffle furnace and calcined at 450 °C for 3 h under a nitrogen flow rate of 30 mm / s and a heating rate of 2 °C / min. Then, the temperature was further increased to 1000 °C and calcined for 3 h. The resulting support was denoted as [missing information]. Its physical properties are shown in Table 1.
[0047] (2) Application of an ordered mesoporous composite oxide support in the preparation of ammonia decomposition hydrogen production catalyst
[0048] The catalyst was prepared using the same method as in Example 1.
[0049] (3) Activity evaluation of ammonia decomposition to hydrogen production catalyst
[0050] The catalyst activity was evaluated under the same conditions as in Example 1. Online gas chromatography analysis of the tail gas composition yielded an ammonia conversion rate of 85.7%.
[0051] Example 3 provides a method for preparing and applying an ordered mesoporous composite oxide support. The specific implementation is as follows:
[0052] (1) Preparation of an ordered mesoporous composite oxide support
[0053] The ordered mesoporous composite oxide support was prepared using the same method as in Example 1, except that the rare earth metals were selected... The resulting carrier is denoted as Its physical properties are shown in Table 1.
[0054] (2) Application of an ordered mesoporous composite oxide support in the preparation of ammonia decomposition hydrogen production catalyst
[0055] The catalyst was prepared using the same method as in Example 1.
[0056] (3) Activity evaluation of ammonia decomposition to hydrogen production catalyst
[0057] The catalyst activity was evaluated under the same conditions as in Example 1. Online gas chromatography analysis of the tail gas composition yielded an ammonia conversion rate of 80.1%.
[0058] Example 4 provides a method for preparing and applying an ordered mesoporous composite oxide support. The specific implementation is as follows:
[0059] (1) Preparation of an ordered mesoporous composite oxide support
[0060] Ordered mesoporous composite oxide supports were prepared using the same method as in Example 1, except that the alkaline earth metal was selected as CaO, and the precursor was calcium nitrate, replacing magnesium nitrate in Example 1. The resulting support is denoted as […]. Its physical properties are shown in Table 1.
[0061] (2) Application of an ordered mesoporous composite oxide support in the preparation of ammonia decomposition hydrogen production catalyst
[0062] The catalyst was prepared using the same method as in Example 1.
[0063] (3) Activity evaluation of ammonia decomposition to hydrogen production catalyst
[0064] The catalyst activity was evaluated under the same conditions as in Example 1. Online gas chromatography analysis of the tail gas composition yielded an ammonia conversion rate of 78.3%.
[0065] Example 5 provides a method for preparing and applying an ordered mesoporous composite oxide support. The specific implementation is as follows:
[0066] (1) Preparation of an ordered mesoporous composite oxide support
[0067] Ordered mesoporous composite oxide supports were prepared using the same method as in Example 1.
[0068] (2) Application of an ordered mesoporous composite oxide support in the preparation of ammonia decomposition hydrogen production catalyst
[0069] The catalyst was prepared using the same method as in Example 1, except that the active metal was a bimetallic combination of Ni and Co, with a molar ratio of 1:1.
[0070] (3) Activity evaluation of ammonia decomposition to hydrogen production catalyst
[0071] The catalyst activity was evaluated under the same conditions as in Example 1. Online gas chromatography analysis of the tail gas composition yielded an ammonia conversion rate of 88.6%.
[0072] Example 6 provides a method for preparing and applying an ordered mesoporous composite oxide support. The specific implementation is as follows:
[0073] (1) Preparation of an ordered mesoporous composite oxide support
[0074] Ordered mesoporous composite oxide supports were prepared using the same method as in Example 1.
[0075] (2) Application of an ordered mesoporous composite oxide support in the preparation of ammonia decomposition hydrogen production catalyst
[0076] The catalyst was prepared using the same method as in Example 1, except that the promoter metal was... .
[0077] (3) Activity evaluation of ammonia decomposition to hydrogen production catalyst
[0078] The catalyst activity was evaluated under the same conditions as in Example 1. Online gas chromatography analysis of the tail gas composition yielded an ammonia conversion rate of 82.6%.
[0079] Comparative Example 1 (reference) Figure 1 and Figure 2 This embodiment provides a traditional preparation method and application of composite oxide supports, and the specific implementation method is as follows:
[0080] (1) Preparation of composite oxide carriers according to traditional methods
[0081] The carrier was prepared using the same method as in Example 1, except that the resulting dry gel was heated directly to 1000°C at a rate of 1°C / min in air, according to the literature method. The resulting carrier is denoted as […]. Its TEM image is shown in the attached image. Figure 1 As shown in the figure, the carrier structure has collapsed, indicating that its ordered mesoporous structure has been destroyed. Its physical properties are shown in Table 1.
[0082] (2) Application of traditional preparation supports in the preparation of ammonia decomposition hydrogen production catalysts
[0083] The ammonia decomposition hydrogen production catalyst was prepared using the same method as in Example 1, and its H2-TPR spectrum is shown below. Figure 2 As shown.
[0084] (3) Activity evaluation of ammonia decomposition to hydrogen production catalyst
[0085] The catalyst activity was evaluated under the same conditions as in Example 1. Online gas chromatography analysis of the tail gas composition yielded an ammonia conversion rate of 53.5%.
[0086] Comparative Example 2 provides a method for preparing and applying a composite oxide support without the addition of alkaline earth metals and rare earth metals. The specific implementation method is as follows:
[0087] (1) Preparation of composite oxide supports without the addition of alkaline earth metals and rare earth metals
[0088] The catalyst was prepared using the same method as in Example 1, except that no alkaline earth metals or rare earth metals were added to the support for modification. The resulting support is denoted as [reference needed]. Its physical properties are shown in Table 1.
[0089] (2) Application of composite oxide supports without added alkaline earth metals and rare earth metals in the preparation of catalysts for hydrogen production from ammonia decomposition
[0090] The catalyst was prepared using the same method as in Example 1. Its H2-TPR spectrum is shown in [Figure / Diagram / Illustration]. Figure 2 As can be seen from the figure, in the unmodified carriers of alkaline earth metals and rare earth metals, there is a strong interaction between the metal and the carrier, which makes it difficult for the active metal to be reduced and activated.
[0091] (3) Evaluation of the activity of ammonia decomposition hydrogen production catalyst
[0092] The catalyst activity was evaluated under the same conditions as in Example 1. Online gas chromatography analysis of the tail gas composition yielded an ammonia conversion rate of 61.8%.
[0093]
[0094] Based on the experimental results and data comparison of the above embodiments and comparative examples, the following conclusions can be clearly drawn:
[0095] The ordered mesoporous composite oxide support and its catalyst provided by this invention exhibit significant comprehensive performance advantages over traditional methods through unique component design and precise control of the preparation process.
[0096] Firstly, the core advantage of this invention is evident in the stability of the carrier structure. As shown in Table 1, the carriers prepared using the specific two-step calcination method of this invention—first removing the template at low temperature in an inert atmosphere, then crystallizing at high temperature with low oxygen concentration—as in Examples 1-4, maintained a specific surface area above 250 m² / g, a pore volume greater than 0.59 cm³ / g, and a uniform average pore size of 9-10 nm after rigorous calcination at 1000℃. In stark contrast, Comparative Example 1, which used a conventional calcination method directly raising the temperature to 1000℃ in an air atmosphere, resulted in a sharp decrease in the specific surface area of the carrier to 113 m² / g, and TEM images clearly showed that its ordered mesoporous structure had completely collapsed. This fully demonstrates that the segmented calcination process described in this invention is crucial for maintaining the ordered mesoporous structure of the carrier and preventing sintering at ultra-high temperatures, and is a key technical guarantee for achieving the "high temperature resistance and sintering resistance" characteristics of the carrier.
[0097] Secondly, regarding the chemical performance and reactivity of the ammonia decomposition hydrogen production catalyst, this invention achieves synergistic enhancement through the optimization of the support composition. All ammonia decomposition hydrogen production catalysts supported on the support of this invention, i.e., Examples 1-6, showed significantly higher ammonia conversion rates than the two comparative examples under the same ammonia decomposition reaction conditions. Specifically, Comparative Example 2, without the addition of alkaline earth and rare earth metals, showed significantly higher ammonia conversion rates. The low activity of the support for the ammonia decomposition hydrogen production catalyst and the strong metal-support interaction shown in the H2-TPR spectrum confirm that the introduction of alkaline earth metals and rare earth metals effectively modulates the electronic environment of the active metal, promoting its reduction and activation, thereby significantly improving its intrinsic activity. Examples 1, 3, and 4, by changing the rare earth metal and alkaline earth metal, all obtained excellent catalytic effects, demonstrating the good universality and flexibility of the support composition design. Examples 5 and 6 further show that loading a dual-active metal Ni-Co on this support or changing the promoter metal to W can also achieve excellent performance, highlighting the good compatibility and carrying capacity of this support.
[0098] In summary, this invention successfully combines an ordered mesoporous composite oxide support with an innovative preparation process, creating a composite oxide support that possesses high specific surface area, regular pores, excellent high-temperature structural stability, and suitable surface chemistry. This support not only effectively stabilizes highly dispersed active metal species but also optimizes the electronic state of the catalytic center through the synergistic effect between the metal oxide components. Ultimately, this results in a breakthrough improvement in both low-temperature activity and long-term operational stability of the prepared ammonia decomposition hydrogen production catalyst, providing an effective technical solution to the common problems of support sintering deactivation and insufficient activity in high-temperature catalytic reactions.
[0099] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.
[0100] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.
[0101] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.
Claims
1. A method for preparing an ordered mesoporous composite oxide carrier, comprising the following steps: (1) dissolving a template agent, polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer P123, in anhydrous ethanol to form an alcohol solution; then adding dilute nitric acid, and then adding aluminum isopropoxide, a soluble salt of an alkaline earth metal, and a soluble salt of a rare earth metal to the above solution to obtain a mixed solution after dissolution; (2) performing solvent evaporation-induced self-assembly on the mixed solution obtained in step (1) at 40-100°C for 10-60 hours to obtain a xerogel; (3) performing staged calcination on the xerogel obtained in step (2): first, raising the temperature to 200-600°C at a rate of 0.5-10°C / min under an inert atmosphere, and then maintaining the temperature for 1-10 hours; then raising the temperature to 1000°C at a rate of 0.5-10°C / min under a mixed gas atmosphere of oxygen and inert gas with an oxygen concentration of 0.1-5%, and then maintaining the temperature for 3 hours to obtain an ordered mesoporous composite oxide carrier; The content of the alkaline earth metal oxide is 5-20% and the content of the rare earth metal oxide is 2-15% by weight of the ordered mesoporous composite oxide carrier, and the rest is .
2. The method of preparing an ordered mesoporous composite oxide support according to claim 1, characterized in that, The alkaline earth metal oxide is one or more of CaO, MgO, BaO, and SrO; the rare earth metal oxide is one or more of , , , and .
3. The method of claim 1, wherein, In step (1), the molar ratio of the template agent P123 to total metal ions is 0.8-3, and the amount of anhydrous ethanol used is such that the concentration of the template agent in the obtained alcohol solution is 0.001-0.04 mol / L.
4. The method of making an ordered mesoporous composite oxide support according to claim 1, wherein, In step (3), the inert atmosphere for the first stage of calcination is nitrogen, and the gas linear velocity is 10-30 mm / s; in the second stage of calcination, the oxygen concentration in the mixed gas atmosphere is controlled to be 0.3-1%.
5. An ordered mesoporous composite oxide support prepared according to the method of any one of claims 1 to 4, characterized in that, After the carrier is subjected to high-temperature calcination at 1000°C for 3 hours, the pore volume is 0.2-0.9 cm³ / g, the specific surface area is 200-400 m² / g, and the average pore diameter is 5-15 nm.
6. Use of an ordered mesoporous composite oxide support in the preparation of a catalyst for hydrogen production by ammonia decomposition, characterized in that, The ammonia decomposition hydrogen production catalyst is prepared by loading active metals and additives on the ordered mesoporous composite oxide carrier; the active metals are selected from one or more of compounds of Ni and compounds of Co; the additives are selected from one or more of compounds of Mo and compounds of W; Based on the total mass of the ammonia decomposition hydrogen production catalyst, the content of the active metal component is 5-20% in terms of oxides, the content of the additive is 1-5%, and the balance is the ordered mesoporous composite oxide carrier.
7. A method for producing an ammonia decomposition hydrogen production catalyst, characterized by, The method comprises: using a stepwise impregnation method to impregnate the ordered mesoporous composite oxide carrier with an impregnation solution containing soluble compounds of active metals and additive metals, and then sequentially performing drying and calcination.
8. The method of claim 7, wherein the catalyst is prepared by the steps of: The temperature for drying is 80-140°C, and the time is 1-10 hours; the calcination is staged calcination, the calcination temperature after the first impregnation is 200-500°C, and the time is 1-8 hours; the calcination temperature after the second impregnation is 300-700°C, and the time is 1-10 hours.
9. A method for hydrogen production by ammonia decomposition, characterized by, The method includes: under the conditions of a reaction temperature of 450-750 DEG C, a pressure of 0-5 MPa, a raw material gas space velocity of 2000-10000 , making ammonia gas react with an ammonia decomposition hydrogen production catalyst.