Bimetal MIL-53-derived porous composite metal oxide material and preparation method thereof, propane dehydrogenation catalyst prepared by adopting porous composite metal oxide material and application of propane dehydrogenation catalyst

Abstract

The invention belongs to the technical field of catalysts, and particularly relates to a bimetal MIL-53-derived porous composite metal oxide material and a preparation method thereof, a propane dehydrogenation catalyst prepared from the bimetal MIL-53-derived porous composite metal oxide material and application of the propane dehydrogenation catalyst. Comprising the following steps: carrying out hydrothermal reaction on aluminum salt, gallium salt and 1, 4-terephthalic acid; carrying out solvent heat treatment on the hydrothermal reaction product, and washing to obtain a bimetallic MIL-53 precursor; the preparation method comprises the following steps: preparing a bimetallic MIL-53 precursor, sequentially calcining the bimetallic MIL-53 precursor in an inert atmosphere and an oxidizing atmosphere to obtain a porous composite metal oxide material, introducing H2 in a nitrogen atmosphere for reduction, and calcining the porous composite metal oxide material in air to obtain the composite metal oxide catalyst. Gallium oxide clusters can be prevented from being formed, it is guaranteed that gallium oxide is evenly dispersed in the material, and meanwhile generation of an active species GaIV is promoted.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, specifically relating to porous composite metal oxide materials derived from bimetallic MIL-53 and their preparation methods, as well as propane dehydrogenation catalysts prepared using these materials and their applications. Background Technology

[0002] Propylene, as one of the most important basic petrochemical products in industrial production, is a raw material for the production of key chemicals such as polypropylene, polyacrylonitrile, acrolein, and acrylic acid. Currently, most propylene is obtained through naphtha steam cracking or petroleum fluidized bed catalytic cracking. However, with the rapid growth in demand for propylene and the scarcity of petroleum resources, the production of propylene through propane dehydrogenation has attracted widespread attention. Pt-Sn, CrOx, and their alloys with metal oxides exhibit high catalytic activity for propane dehydrogenation, but they still have some drawbacks. For example, Pt-based catalysts are prone to sintering and carbon deposition during catalysis, leading to catalyst deactivation; CrOx catalysts pose toxicity and environmental pollution problems during catalysis. However, Ga2O3-based catalysts offer advantages such as low toxicity and low cost for propane dehydrogenation, thus attracting widespread attention.

[0003] Metal-organic frameworks (MOFs), as a class of porous materials with well-defined crystal structures and easily customizable porosity, have been widely used in many fields. However, the fragile and unstable coordination bonds between metal nodes and organic ligands, especially in aqueous environments, significantly limit the practical applications of MOFs. Nevertheless, MOFs can be used as templates or precursors to degenerate more stable porous materials, such as porous carbon, metal-based compounds, and their composites, through calcination in air or pyrolysis under an inert gas atmosphere. These MOF derivatives largely retain the structural characteristics of the original MOFs, such as large specific surface area, compositional diversity, and tunable porosity. Metal oxides obtained by directly calcining MOF precursors in an air atmosphere can be used as catalysts or supports in heterogeneous catalytic reactions, including hydrogenation, oxidation, Fischer-Tropsch synthesis, and dehydrogenation. However, when MOF precursors are calcined directly in air, the rapid combustion of organic ligands generates local high temperatures due to the exothermic effect. This easily leads to the aggregation of highly mobile Ga species, forming independent Ga2O3 crystal phases, thereby reducing the number and dispersion of active sites and limiting further improvement of catalyst activity.

[0004] In the post-treatment and activation of catalysts, traditional methods typically involve only simple thermal treatment, lacking precise means to control the chemical environment and active site state of the catalyst surface. How to effectively construct and stabilize active centers on the catalyst surface and create abundant oxygen vacancies to enhance catalytic activity is another challenge facing existing technologies. In summary, there is an urgent need in this field for a novel catalyst preparation strategy that can fundamentally solve the problem of metal species aggregation and precisely control the structure of active sites. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a porous composite metal oxide material derived from bimetallic MIL-53, which can effectively suppress the phase separation of Ga2O3.

[0006] The present invention also provides a preparation method that is simple, easy to implement, and suitable for large-scale production.

[0007] The present invention also provides a propane dehydrogenation catalyst prepared therefrom, which significantly improves the propane conversion rate.

[0008] The present invention also provides its applications.

[0009] The preparation method of the bimetallic MIL-53-derived porous composite metal oxide material of the present invention includes the following steps: (1) Aluminum salt, gallium salt and 1,4-terephthalic acid are subjected to hydrothermal reaction to obtain hydrothermal reaction products; wherein the molar ratio of aluminum ions to gallium ions is 13:7 to 17:3. (2) The hydrothermal reaction product is subjected to solvothermal treatment, followed by solvent exchange washing to obtain the bimetallic MIL-53 precursor; (3) The bimetallic MIL-53 precursor is subjected to stepwise dynamic atmosphere calcination, wherein the calcination includes: (a) Under an inert atmosphere, the precursor is heated to 555°C to 655°C and subjected to a first stage of heat preservation. (b) Then, the atmosphere is switched to an oxidizing atmosphere and a second stage of heat preservation is carried out to obtain a porous composite metal oxide material.

[0010] The hydrothermal reaction in step (1) is carried out at a temperature of 200°C for 72 hours.

[0011] The solvent used in the solvent heat treatment in step (2) is N,N-dimethylformamide (DMF).

[0012] The solvent exchange washing in step (2) is performed using N,N-dimethylformamide and methanol.

[0013] After step (3), a post-treatment step of washing and drying the porous composite metal oxide material is also included.

[0014] During the research process, the inventors first made a breakthrough by exploring advanced heat treatment strategies beyond the traditional one-step method. They attempted a two-step method to prepare composite metal oxides: first, pyrolysis in an inert atmosphere, followed by calcination in an oxidizing atmosphere. This was combined with a hydrogen reduction-oxidation activation treatment to control the active sites of the catalyst. The basic idea is to use mild pyrolysis in an inert atmosphere to avoid violent combustion, utilizing the generated carbon matrix to initially fix the metal species; then, hydrogen reduction is used to create oxygen vacancies. The results were significantly improved compared to the conventional one-step process. However, in in-depth research on the high-gallium-content bimetallic MIL-53(Al,Ga) system specific to this invention, the inventors found that even with the more advanced two-step method and reduction activation process, the results were still not ideal, failing to fundamentally solve the problem. The underlying reason is that during the isothermal inert atmosphere holding stage, highly mobile gallium species still have sufficient time and driving force to undergo secondary migration and aggregation. When switching abruptly from an inert atmosphere to an oxidizing atmosphere, the enriched carbon matrix undergoes violent and uneven combustion, triggering localized overheating in the microscopic regions. This significantly diminishes the dispersion effect achieved through the initial pyrolysis, ultimately leading to the formation of independent Ga2O3 clusters. Furthermore, for partially aggregated oxides, subsequent continuous, long-term isothermal hydrogen reduction fails to effectively redisperse the formed clusters. Moreover, this static reduction process can result in a monolithic state of active sites or deactivation due to over-reduction.

[0015] Step (a) specifically involves heating to 350-450℃ at a rate of 2-3℃ / min, then heating to 555-655℃ at a rate of 5-8℃ / min, followed by a first-stage holding period of 3 hours. This slow-then-fast heating strategy achieves the orderly stepwise pyrolysis of organic ligands, avoiding the gas impact that damages the material structure caused by rapid initial heating, and allowing rapid passage through the high-temperature region, thus reducing the time window for gallium species migration. This maximizes the preservation of the porous morphology of the MOF and forms a uniform insulating carbon layer.

[0016] Step (b) specifically involves gradually injecting an oxidizing gas into an inert atmosphere, increasing its concentration linearly or stepwise from 0% to 100% over 0.5-2 hours. This is followed by a second-stage holding period in a pure oxidizing atmosphere for 7-9 hours. This process achieves gentle and uniform oxidation removal of the carbon matrix, fundamentally eliminating localized overheating caused by abrupt atmospheric changes and ensuring that the isolated metal species can be oxidized in situ without the risk of secondary agglomeration.

[0017] The propane dehydrogenation catalyst of the present invention, which is prepared using a porous composite metal oxide material derived from bimetallic MIL-53, is prepared by the following method: the porous composite metal oxide material derived from bimetallic MIL-53 is subjected to reduction-oxidation heat treatment or loaded with metal Pt, thereby obtaining the propane dehydrogenation catalyst.

[0018] The reduction-oxidation heat treatment specifically involves: alternating pulses of a reducing atmosphere at the heat treatment temperature, introducing 10% H2 / N2 for 10-30 minutes; followed by pulses of an inert atmosphere, introducing N2 for 5-15 minutes, repeating this cycle 3-5 times. Finally, a final heat treatment is performed under an oxidizing atmosphere.

[0019] In a reducing atmosphere (H2), H2 reacts with lattice oxygen on the surface of metal oxides to generate water, leaving oxygen vacancies. Continuous reduction can lead to excessive accumulation of oxygen vacancies, potentially causing surface structure collapse or metal deactivation due to excessive reduction. Short reduction pulses remove only surface lattice oxygen, generating a limited but uniform number of oxygen vacancies; subsequent inert purging removes the byproduct water vapor, preventing water molecule re-adsorption or surface re-oxidation, thus temporarily stabilizing the oxygen vacancies. Cyclic pulses, across multiple reduction-purging cycles, continuously generate, stabilize, and partially recombine oxygen vacancies, forming a dynamic equilibrium. This simulates the real environment in catalytic reactions: the breaking of CH bonds in propane dehydrogenation requires oxygen vacancies, allowing the catalyst to adapt to dynamic changes and improving the regenerability of oxygen vacancies. Prolonged exposure to H2 leads to continuous removal of bulk lattice oxygen, causing deep reduction of metal oxides, damaging the porous structure, and resulting in active site aggregation. Short pulses limit reduction to the surface and near-surface regions, protecting the bulk structure; the purging step interrupts the reduction process, allowing surface atomic rearrangement and inhibiting metal migration and aggregation.

[0020] Compared to continuous long-term reduction, cyclic pulse treatment can more effectively generate dynamic and regenerable oxygen vacancies and coordination-unsaturated active sites at the metal-support interface, and promote the transformation of Ga species into active Ga. IV Transformation of state.

[0021] Specifically, the preparation method of the bimetallic MIL-53-derived porous composite metal oxide material includes the following steps: (1) Dissolve Al(NO3)3•9H2O, Ga(NO3)3•xH2O and 1,4-terephthalic acid in water, with a molar ratio of aluminum ions to gallium ions of 13:7 to 17:3. Stir until completely dissolved to obtain a clear solution. Transfer the clear solution to a reaction vessel and seal it. Place it in a 200℃ oven for crystallization for 72 hours, and then collect the product. (2) The product from step (1) was dissolved in DMF solvent, then transferred to a sealed reactor and placed in a 150°C oven for 12 hours. The product was collected and then washed three times with DMF and methanol respectively to obtain bimetallic MIL-53 (Al x Ga 2-x (x=1.3~1.7) precursor; (3) The bimetallic MIL-53 precursor was placed in a tube furnace and heated to 350-450°C at a rate of 2-3°C / min under a nitrogen atmosphere. Then, the temperature was increased to 555-655°C at a rate of 5-8°C / min and held for 3 hours. An oxidizing gas was gradually injected into the inert atmosphere, and its concentration was increased linearly or stepwise from 0% to 100% in 0.5-2 hours. Then, the mixture was calcined under a pure oxidizing atmosphere for 7-9 hours. The gas flow rate was 30 mL / min. After the tube furnace cooled to room temperature, the white powder product was collected, washed with ethanol, and dried under a nitrogen atmosphere to obtain a porous composite metal oxide material derived from bimetallic MIL-53 (Al, Ga).

[0022] The propane dehydrogenation catalyst prepared using the porous composite metal oxide material derived from bimetallic MIL-53 is obtained by the following method: A1. The porous composite metal oxide material obtained in step (3) is heated to 500℃ in a nitrogen atmosphere at a rate of 5℃ / min, and alternating reducing atmosphere pulses are performed: 10% H2 / N2 is introduced for 20min, then switched to an inert atmosphere for 10min, and this process is repeated 3-5 times. Finally, it is calcined in an oxidizing atmosphere for 3h to obtain the composite metal oxide catalyst. The gas flow rate is 30mL / min, i.e., the composite metal oxide Al x Ga 2-x O3@T℃(x=1.3~1.7; T=555~655).

[0023] or: A2. The porous composite metal oxide material obtained in step (3) is impregnated in chloroplatinic acid solution, stirred for 2 hours, placed in a tube furnace, and calcined at 500°C for 3 hours under flowing air at a rate of 5°C / min to obtain the Pt-supported composite metal oxide catalyst, namely Pt-Al. x Ga 2-x O3@T℃ (x=1.3~1.7; T=555~655), Pt loading is 0.5wt.%.

[0024] The propane dehydrogenation catalyst described in this invention is used to catalyze the propane dehydrogenation reaction. Before use, the propane dehydrogenation catalyst needs to be activated by heating in an inert atmosphere.

[0025] The activation temperature was 500℃, the inert atmosphere flow rate was 50mL / min, and the activation time was 2h.

[0026] Specifically, the reaction is carried out under atmospheric pressure in a continuous flow system equipped with a fixed-bed quartz tube reactor. Before the reaction, the catalyst is activated for 2 hours at 500°C and a helium flow rate of 50 mL / min. Then, propane is introduced into the reactor with nitrogen as the carrier gas and reacted at 550°C for 180 minutes, with a total flow rate of 20 mL / min.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) This invention, through a revolutionary upgrade from static step-by-step to full-process dynamic fine-tuning, successfully achieves full-process, effective confinement of highly mobile gallium species throughout the entire heat treatment process, solving the problems of secondary migration and localized overheating that even conventional two-step methods cannot overcome. Simultaneously, compared to continuous reduction, dynamic "cyclic pulse activation" can more effectively generate dynamic, regenerable, and more diverse oxygen vacancies and unsaturated active sites at the metal-support interface, and efficiently promote the transformation of Ga species into active Ga. IV The material exhibits excellent propane dehydrogenation to propylene activity compared to traditional Ga2O3-Al2O3 materials, enabling the transformation of the state.

[0028] 2) In the metal oxide of the present invention, gallium oxide is uniformly dispersed in the material, which greatly enhances the four-coordinate gallium (Ga) content. Ⅳ The active site acts as a catalyst, promoting the catalytic reaction. Simultaneously, this material contains abundant five-coordinated aluminum (Al). Ⅴ It can be used as an anchor point for metal.

[0029] 3) The bimetallic MIL-53(Al, Ga)-derived porous composite metal oxide Al prepared in this invention x Ga 2-x When O3 material is used in the propane dehydrogenation reaction, the material contains a large amount of pentacoordinated aluminum (Al). Ⅴ It can serve as an anchoring point for metallic Pt, thus enabling the production of Pt-loaded composite metal oxides. Furthermore, the material contains tetracoordinated gallium (Ga). Ⅳ As the active species and metal Pt as the promoter, the synergistic effect between the two enables the catalyst to exhibit high catalytic activity for propane dehydrogenation while maintaining high selectivity for the catalytic product propylene. Furthermore, regardless of whether Pt is supported, its catalytic activity is significantly superior to existing technologies. Attached Figure Description

[0030] Figure 1 MIL-53 (Al) 1.3 Ga0.7 Al 1.3 Ga 0.7 O3@555℃, Al 1.3 Ga 0.7 O3@600℃ and Al 1.3 Ga 0.7 XRD diffraction pattern of O3 at 655℃; Figure 2 MIL-53 (Al) 1.7 Ga 0.3 Al 1.7 Ga 0.3 O3@555℃, Al 1.7 Ga 0.3 O3@600℃ and Al 1.7 Ga 0.3 XRD diffraction pattern of O3 at 655℃; Figure 3 Pt-Al 1.7 Ga 0.3 O3@555℃, Pt-Al 1.7 Ga 0.3 O3@600℃ and Pt-Al 1.7 Ga 0.3 XRD diffraction pattern of O3 at 655℃; Figure 4 For Al 1.7 Ga 0.3 TEM image of O3 at 555℃; Figure 5 MIL-53 (Al) 1.3 Ga 0.7 Al 1.3 Ga 0.7 O3@555℃, Al 1.3 Ga 0.7 O3@600℃ and Al 1.3 Ga 0.7 O3@655℃ 27 Al solid NMR spectrum; Figure 6 MIL-53 (Al) 1.7 Ga 0.3 Al 1.7 Ga 0.3 O3@555℃, Al 1.7 Ga 0.3 O3@600℃ and Al 1.7 Ga 0.3 O3@655℃ 27 Al solid NMR spectrum; Figure 7 Pt-Al1.7 Ga 0.3 O3@555℃, Pt-Al 1.7 Ga 0.3 O3@600℃ and Pt-Al 1.7 Ga 0.3 O3@655℃ 27 Al solid NMR spectrum; Figure 8 MIL-53 (Al) 1.3 Ga 0.7 ) and MIL-53 (Al 1.7 Ga 0.3 )of 71 Ga solid NMR spectrum; Figure 9 For Al 1.3 Ga 0.7 O3@555℃, Al 1.3 Ga 0.7 O3@600℃ and Al 1.3 Ga 0.7 O3@655℃ 71 Ga solid NMR spectrum; Figure 10 For Al 1.7 Ga 0.3 O3@555℃, Al 1.7 Ga 0.3 O3@600℃ and Al 1.7 Ga 0.3 O3@655℃ 71 Ga solid NMR spectrum; Figure 11 For Al 1.3 Ga 0.7 O3@555℃, Al 1.3 Ga 0.7 O3@600℃ and Al 1.3 Ga 0.7 Results of the catalytic activity of O3 at 655℃ for propane dehydrogenation reaction; Figure 12 For Al 1.7 Ga 0.3 O3@555℃, Al 1.7 Ga 0.3 O3@600℃ and Al 1.7 Ga 0.3 Results of the catalytic activity of O3 at 655℃ for propane dehydrogenation reaction; Figure 13 Pt-Al 1.7 Ga 0.3 O3@555℃, Pt-Al 1.7 Ga0.3 O3@600℃ and Pt-Al 1.7 Ga 0.3 Catalytic activity of O3 at 655℃ for propane dehydrogenation reaction; Figure 14 For Al 1.7 Ga 0.3 XRD diffraction pattern of O3@555℃#; Figure 15 For Al 1.7 Ga 0.3 O3@555℃# 71 Ga solid NMR spectrum; Figure 16 For Al 1.7 Ga 0.3 XRD diffraction pattern of O3@555℃##; Figure 17 For Al 1.7 Ga 0.3 O3@555℃## 71 Ga solid NMR spectrum; Figure 18 For Al 1.7 Ga 0.3 XRD diffraction pattern of O3 at 555℃; Figure 19 For Al 1.7 Ga 0.3 O3@555℃### 71 Ga solid NMR spectrum; Figure 20 For Al 1.7 Ga 0.3 XRD diffraction pattern of O3 at 555℃; Figure 21 For Al 1.7 Ga 0.3 O3@555℃#### 71 Ga solid NMR spectrum; Figure 22 For Al 1.7 Ga 0.3 Results of the catalytic activity of O3 at 555℃ for propane dehydrogenation. Detailed Implementation

[0031] The present invention will be further described below with reference to the embodiments.

[0032] Unless otherwise specified, all raw materials used in the examples were commercially available.

[0033] All gas ratios used below are volume ratios.

[0034] Example 1 The preparation method of the bimetallic MIL-53-derived porous composite metal oxide material includes the following steps: (1) Dissolve 32.5 mmol Al(NO3)3•9H2O, 17.5 mmol Ga(NO3)3•xH2O and 4.8 mmol H2BDC in 30 mL of water and stir until completely dissolved to obtain a clear solution; transfer the clear solution to a reaction vessel and seal it, place it in an oven at 200 °C for 72 h to crystallize, and then collect the product; (2) Dissolve the product from step (1) in 60 mL of DMF solvent, then transfer it to a reaction vessel and seal it. Place it in a 150 °C oven for 12 h, collect the product, and then wash it three times with DMF and methanol respectively to obtain bimetallic MIL-53 (Al 1.3 Ga 0.7 )sample; (3) The bimetallic MIL-53 sample prepared in step (2) was placed in a tube furnace as a precursor. The temperature was first increased to 450°C at a rate of 3°C / min under a nitrogen atmosphere, then increased to 555°C at a rate of 8°C / min and held for 3 hours. Air was gradually injected into the inert atmosphere, increasing its concentration linearly or stepwise from 0% to 100% within 2 hours. The furnace was then calcined in flowing air for 7 hours, with the airflow rate being 30 mL / min. After the tube furnace cooled to room temperature, the white powder product was collected, washed with ethanol, and dried under a nitrogen atmosphere to obtain the derivative of bimetallic MIL-53 (Al, Ga), namely the composite metal oxide Al. 1.3 Ga 0.7 O3@555℃.

[0035] The propane dehydrogenation catalyst prepared using the porous composite metal oxide material derived from bimetallic MIL-53 is obtained by the following method: A1. The material obtained in step (3) is heated to 500℃ at a rate of 5℃ / min under a nitrogen atmosphere, and alternating reducing atmosphere pulses are performed: 10% H2 / N2 is introduced for 20min, then switched to N2 for 10min, and this process is repeated for 5 cycles. Finally, it is calcined in air for 3h to obtain the composite metal oxide catalyst Al. 1.3 Ga 0.7 O3@555℃, with an airflow rate of 30 mL / min.

[0036] test: Al composite metal oxide 1.3 Ga 0.7O3 at 555℃ was first tableted, then crushed and sieved to obtain uniformly sized oxide particles, which were then loaded into a reactor. Propane dehydrogenation was then carried out under atmospheric pressure in a continuous flow system equipped with a fixed-bed quartz tube reactor. Before the reaction, the catalyst was activated for 2 h at 500℃ and a helium flow rate of 50 mL / min. Afterwards, propane was introduced into the reactor using nitrogen as a carrier gas and reacted at 550℃ for 180 min (propane / nitrogen = 1:9) at a total flow rate of 20 mL / min. At 35 min of reaction time, the propane conversion was 46.4%, and the propylene selectivity was 92.2%.

[0037] Example 2 The preparation method of the bimetallic MIL-53-derived porous composite metal oxide material includes the following steps: (1) Dissolve 32.5 mmol Al(NO3)3•9H2O, 17.5 mmol Ga(NO3)3•xH2O and 4.8 mmol H2BDC in 30 mL of water and stir until completely dissolved to obtain a clear solution; transfer the clear solution to a reaction vessel and seal it, place it in an oven at 200 °C for 72 h to crystallize, and then collect the product; (2) Dissolve the product from step (1) in 60 mL of DMF solvent, then transfer it to a reaction vessel and seal it. Place it in a 150 °C oven for 12 h, collect the product, and then wash it three times with DMF and methanol respectively to obtain bimetallic MIL-53 (Al 1.3 Ga 0.7 )sample; (3) The bimetallic MIL-53 sample prepared in step (2) was placed in a tube furnace as a precursor. The temperature was first increased to 450°C at a rate of 3°C / min under a nitrogen atmosphere, then increased to 600°C at a rate of 8°C / min and held for 3 hours. Air was gradually injected into the inert atmosphere, increasing its concentration linearly or stepwise from 0% to 100% within 1 hour. The furnace was then calcined in flowing air for 8 hours, with the airflow rate being 30 mL / min. After the tube furnace cooled to room temperature, the white powder product was collected, washed with ethanol, and dried under a nitrogen atmosphere to obtain the derivative of bimetallic MIL-53 (Al, Ga), namely the composite metal oxide Al. 1.3 Ga 0.7 O3@600℃.

[0038] The propane dehydrogenation catalyst prepared using the porous composite metal oxide material derived from bimetallic MIL-53 is obtained by the following method: A1. The material obtained in step (3) is heated to 500℃ at a rate of 5℃ / min under a nitrogen atmosphere, and alternating reducing atmosphere pulses are performed: 10% H2 / N2 is introduced for 20min, then switched to N2 for 10min, and this process is repeated for 5 cycles. Finally, it is calcined in air for 3h to obtain the composite metal oxide catalyst Al. 1.3 Ga 0.7 O3@600℃, with an airflow rate of 30 mL / min.

[0039] test: Al composite metal oxide 1.3 Ga 0.7 O3 at 600℃ was first tableted, then crushed and sieved to obtain uniformly sized oxide particles, which were then loaded into a reactor. Propane dehydrogenation was then carried out under atmospheric pressure in a continuous flow system equipped with a fixed-bed quartz tube reactor. Before the reaction, the catalyst was activated for 2 h at 500℃ and a helium flow rate of 50 mL / min. Afterwards, propane was introduced into the reactor using nitrogen as a carrier gas and reacted at 550℃ for 180 min (propane / nitrogen = 1:9), with a total flow rate of 20 mL / min. At 35 min of reaction time, the propane conversion was 48.5%, and the propylene selectivity was 91.9%.

[0040] Example 3 The preparation method of the bimetallic MIL-53-derived porous composite metal oxide material includes the following steps: (1) Dissolve 32.5 mmol Al(NO3)3•9H2O, 17.5 mmol Ga(NO3)3•xH2O and 4.8 mmol H2BDC in 30 mL of water and stir until completely dissolved to obtain a clear solution; transfer the clear solution to a reaction vessel and seal it, place it in an oven at 200 °C for 72 h to crystallize, and then collect the product; (2) Dissolve the product from step (1) in 60 mL of DMF solvent, then transfer it to a reaction vessel and seal it. Place it in a 150 °C oven for 12 h, collect the product, and then wash it three times with DMF and methanol respectively to obtain bimetallic MIL-53 (Al 1.3 Ga 0.7 )sample; (3) The bimetallic MIL-53 sample prepared in step (2) was placed in a tube furnace as a precursor. The temperature was first increased to 450°C at a rate of 3°C / min under a nitrogen atmosphere, then increased to 655°C at a rate of 6°C / min and held for 3 hours. Air was gradually injected into the inert atmosphere, increasing its concentration linearly or stepwise from 0% to 100% within 0.5 hours. The furnace was then calcined in flowing air for 9 hours, with a flow rate of 30 mL / min. After the tube furnace cooled to room temperature, the white powder product was collected, washed with ethanol, and dried under a nitrogen atmosphere to obtain the derivative of bimetallic MIL-53 (Al, Ga), namely the composite metal oxide Al. 1.3 Ga 0.7 O3@655℃.

[0041] The propane dehydrogenation catalyst prepared using the porous composite metal oxide material derived from bimetallic MIL-53 is obtained by the following method: A1. The material obtained in step (3) is heated to 500℃ at a rate of 5℃ / min under a nitrogen atmosphere, and alternating reducing atmosphere pulses are performed: 10% H2 / N2 is introduced for 20min, then switched to N2 for 10min, and this process is repeated for 5 cycles. Finally, it is calcined in air for 3h to obtain the composite metal oxide catalyst Al. 1.3 Ga 0.7 O3@655℃, with an airflow rate of 30 mL / min.

[0042] test: Al composite metal oxide 1.3 Ga 0.7 O3 at 655℃ was first tableted, then crushed and sieved to obtain uniformly sized oxide particles, which were then loaded into a reactor. Propane dehydrogenation was then carried out under atmospheric pressure in a continuous flow system equipped with a fixed-bed quartz tube reactor. Before the reaction, the catalyst was activated for 2 h at 500℃ and a helium flow rate of 50 mL / min. Afterwards, propane was introduced into the reactor using nitrogen as a carrier gas and reacted at 550℃ for 180 min (propane / nitrogen = 1:9) at a total flow rate of 20 mL / min. At 35 min of reaction time, the propane conversion was 50.0%, and the propylene selectivity was 91.0%.

[0043] MIL-53 (Al) 1.3 Ga 0.7 Al 1.3 Ga 0.7 O3@555℃, Al 1.3 Ga 0.7 O3@600℃ and Al 1.3 Ga 0.7The XRD diffraction pattern of O3 at 655℃ is as follows: Figure 1 As shown. MIL-53 (Al) 1.3 Ga 0.7 Al 1.3 Ga 0.7 O3@555℃, Al 1.3 Ga 0.7 O3@600℃ and Al 1.3 Ga 0.7 O3@655℃ 27 Al solid NMR spectrum as shown Figure 5 As shown. Al 1.3 Ga 0.7 O3@555℃, Al 1.3 Ga 0.7 O3@600℃ and Al 1.3 Ga 0.7 O3@655℃ 71 Ga solid NMR spectrum as shown in Figure 9 As shown.

[0044] Example 4 The preparation method of the bimetallic MIL-53-derived porous composite metal oxide material includes the following steps: (1) Dissolve 42.5 mmol Al(NO3)3•9H2O, 7.5 mmol Ga(NO3)3•xH2O and 4.8 mmol H2BDC in 30 mL of water and stir until completely dissolved to obtain a clear solution; transfer the clear solution to a reaction vessel and seal it, place it in an oven at 200 °C for 72 h to crystallize, and then collect the product; (2) Dissolve the product from step (1) in 60 mL of DMF solvent, then transfer it to a reaction vessel and seal it. Place it in a 150 °C oven for 12 h, collect the product, and then wash it three times with DMF and methanol respectively to obtain bimetallic MIL-53 (Al 1.7 Ga 0.3 )sample; (3) The bimetallic MIL-53 sample prepared in step (2) was placed in a tube furnace as a precursor. The temperature was first increased to 350°C at a rate of 2°C / min under a nitrogen atmosphere, then increased to 555°C at a rate of 5°C / min, and held for 3 hours. Air was gradually injected into the inert atmosphere, increasing its concentration linearly or stepwise from 0% to 100% within 2 hours. The furnace was then calcined in flowing air for 7 hours, with the airflow rate being 30 mL / min. After the tube furnace cooled to room temperature, the white powder product was collected, washed with ethanol, and dried under a nitrogen atmosphere to obtain the derivative of bimetallic MIL-53 (Al, Ga), namely the composite metal oxide Al. 1.7 Ga0.3 O3@555℃.

[0045] The propane dehydrogenation catalyst prepared using the porous composite metal oxide material derived from bimetallic MIL-53 is obtained by the following method: A1. The material obtained in step (3) is heated to 500℃ at a rate of 5℃ / min under a nitrogen atmosphere, and alternating reducing atmosphere pulses are performed: 10% H2 / N2 is introduced for 20min, then switched to N2 for 10min, and this process is repeated for 5 cycles. Finally, it is calcined in air for 3h to obtain the composite metal oxide catalyst Al. 1.7 Ga 0.3 O3@555℃, with an airflow rate of 30 mL / min.

[0046] test: Al composite metal oxide 1.7 Ga 0.3 O3 at 555℃ was first tableted, then crushed and sieved to obtain uniformly sized oxide particles, which were then loaded into a reactor. Propane dehydrogenation was then carried out under atmospheric pressure in a continuous flow system equipped with a fixed-bed quartz tube reactor. Before the reaction, the catalyst was activated for 2 h at 500℃ and a helium flow rate of 50 mL / min. Afterwards, propane was introduced into the reactor using nitrogen as a carrier gas and reacted at 550℃ for 180 min (propane / nitrogen = 1:9) at a total flow rate of 20 mL / min. At 35 min of reaction time, the propane conversion was 47.6%, and the propylene selectivity was 91.7%.

[0047] Al 1.7 Ga 0.3 TEM image of O3 at 555℃ as follows Figure 4 As shown. MIL-53 (Al) 1.3 Ga 0.7 ) and MIL-53 (Al 1.7 Ga 0.3 )of 71 Ga solid NMR spectrum as shown in Figure 8 As shown. Al 1.3 Ga 0.7 O3@555℃, Al 1.3 Ga 0.7 O3@600℃ and Al 1.3 Ga 0.7 The catalytic activity of O3 at 655℃ for propane dehydrogenation is as follows: Figure 11 As shown.

[0048] Example 5 The propane dehydrogenation catalyst prepared using the porous composite metal oxide material derived from bimetallic MIL-53 is obtained by the following method: A certain amount of Al 1.7 Ga 0.3 O3 was impregnated in 5 mL of chloroplatinic acid solution at 555 °C, and then stirred at 60 °C. Subsequently, it was calcined in a tube furnace at 500 °C in flowing air for 3 h to obtain the Pt-supported composite metal oxide Pt-Al. 1.7 Ga 0.3 O3@555℃ catalyst, with a Pt loading of 0.5 wt.%.

[0049] test: Pt-Al composite metal oxide loaded with Pt 1.7 Ga 0.3 O3 at 555℃ was first tableted, then crushed and sieved to obtain uniformly sized oxide particles, which were then loaded into a reactor. Propane dehydrogenation was then carried out under atmospheric pressure in a continuous flow system equipped with a fixed-bed quartz tube reactor. Before the reaction, the catalyst was activated for 2 h at 500℃ and a helium flow rate of 50 mL / min. Afterwards, propane was introduced into the reactor using nitrogen as a carrier gas and reacted at 550℃ for 180 min (propane / nitrogen = 1:9) at a total flow rate of 20 mL / min. At 35 min of reaction time, the propane conversion was 81.2%, and the propylene selectivity was 83.2%.

[0050] Example 6 The preparation method of the bimetallic MIL-53-derived porous composite metal oxide material includes the following steps: (1) Dissolve 42.5 mmol Al(NO3)3•9H2O, 7.5 mmol Ga(NO3)3•xH2O and 4.8 mmol H2BDC in 30 mL of water and stir until completely dissolved to obtain a clear solution; transfer the clear solution to a reaction vessel and seal it, place it in an oven at 200 °C for 72 h to crystallize, and then collect the product; (2) Dissolve the product from step (1) in 60 mL of DMF solvent, then transfer it to a reaction vessel and seal it. Place it in a 150 °C oven for 12 h, collect the product, and then wash it three times with DMF and methanol respectively to obtain bimetallic MIL-53 (Al 1.7 Ga 0.3 )sample; (3) The bimetallic MIL-53 sample prepared in step (2) was placed in a tube furnace as a precursor. The temperature was first increased to 350°C at a rate of 2°C / min under a nitrogen atmosphere, then increased to 600°C at a rate of 5°C / min, and held for 3 hours. Air was gradually injected into the inert atmosphere, increasing its concentration linearly or stepwise from 0% to 100% within 1 hour. The furnace was then calcined in flowing air for 8 hours, with the airflow rate being 30 mL / min. After the tube furnace cooled to room temperature, the white powder product was collected, washed with ethanol, and dried under a nitrogen atmosphere to obtain the derivative of bimetallic MIL-53 (Al, Ga), namely the composite metal oxide Al. 1.7 Ga 0.3 O3@600℃.

[0051] The propane dehydrogenation catalyst prepared using the porous composite metal oxide material derived from bimetallic MIL-53 is obtained by the following method: A1. The material obtained in step (3) is heated to 500℃ at a rate of 5℃ / min under a nitrogen atmosphere, and alternating reducing atmosphere pulses are performed: 10% H2 / N2 is introduced for 20min, then switched to N2 for 10min, and this process is repeated for 5 cycles. Finally, it is calcined in air for 3h to obtain the composite metal oxide catalyst Al. 1.7 Ga 0.3 O3@600℃, with an airflow rate of 30 mL / min.

[0052] test: Al composite metal oxide 1.7 Ga 0.3 O3 at 600℃ was first tableted, then crushed and sieved to obtain uniformly sized oxide particles. 130 mg of these particles were weighed and loaded into the reactor, where propane dehydrogenation was carried out under atmospheric pressure in a continuous flow system equipped with a fixed-bed quartz tube reactor. Before the reaction, the catalyst was activated for 2 h at 500℃ and a helium flow rate of 50 mL / min. Then, propane was introduced into the reactor using nitrogen as a carrier gas and reacted at 550℃ for 180 min (propane / nitrogen = 1:9) at a total flow rate of 20 mL / min. After 35 min of reaction, the propane conversion was 51.3%, and the propylene selectivity was 87.8%.

[0053] Example 7 The propane dehydrogenation catalyst prepared using the porous composite metal oxide material derived from bimetallic MIL-53 is obtained by the following method: A2. A certain amount of Al 1.7 Ga 0.3O3 was impregnated in 5 mL of chloroplatinic acid solution at 600 °C, and then stirred at 60 °C. Subsequently, it was calcined in a tube furnace at 500 °C in flowing air for 3 h to obtain the Pt-supported composite metal oxide Pt-Al. 1.7 Ga 0.3 O3@600℃ catalyst, with Pt loading of 0.5 wt.%.

[0054] test: Pt-Al composite metal oxide loaded with Pt 1.7 Ga 0.3 O3 at 600℃ was first tableted, then crushed and sieved to obtain uniformly sized oxide particles, which were then loaded into a reactor. Propane dehydrogenation was then carried out under atmospheric pressure in a continuous flow system equipped with a fixed-bed quartz tube reactor. Before the reaction, the catalyst was activated for 2 h at 500℃ and a helium flow rate of 50 mL / min. Afterwards, propane was introduced into the reactor using nitrogen as a carrier gas and reacted at 550℃ for 180 min (propane / nitrogen = 1:9), with a total flow rate of 20 mL / min. At 35 min of reaction time, the propane conversion was 81.5%, and the propylene selectivity was 71.4%.

[0055] Example 8 (1) Dissolve 42.5 mmol Al(NO3)3•9H2O, 7.5 mmol Ga(NO3)3•xH2O and 4.8 mmol H2BDC in 30 mL of water and stir until completely dissolved to obtain a clear solution; transfer the clear solution to a reaction vessel and seal it, place it in an oven at 200 °C for 72 h to crystallize, and then collect the product; (2) Dissolve the product from step (1) in 60 mL of DMF solvent, then transfer it to a reaction vessel and seal it. Place it in a 150 °C oven for 12 h, collect the product, and then wash it three times with DMF and methanol respectively to obtain bimetallic MIL-53 (Al 1.7 Ga 0.3 )sample; (3) The bimetallic MIL-53 sample prepared in step (2) was placed in a tube furnace as a precursor. The temperature was first increased to 350°C at a rate of 2°C / min under a nitrogen atmosphere, then increased to 655°C at a rate of 5°C / min, and held for 3 hours. Air was gradually injected into the inert atmosphere, increasing its concentration linearly or stepwise from 0% to 100% within 0.5 hours. The furnace was then calcined in flowing air for 9 hours, with a flow rate of 30 mL / min. After the tube furnace cooled to room temperature, the white powder product was collected, washed with ethanol, and dried under a nitrogen atmosphere to obtain the derivative of bimetallic MIL-53 (Al, Ga), namely the composite metal oxide Al.1.7 Ga 0.3 O3@655℃.

[0056] The propane dehydrogenation catalyst prepared using the porous composite metal oxide material derived from bimetallic MIL-53 is obtained by the following method: A1. The material obtained in step (3) is heated to 500℃ at a rate of 5℃ / min under a nitrogen atmosphere, and alternating reducing atmosphere pulses are performed: 10% H2 / N2 is introduced for 20min, then switched to N2 for 10min, and this process is repeated for 5 cycles. Finally, it is calcined in air for 3h to obtain the composite metal oxide catalyst Al. 1.7 Ga 0.3 O3@655℃, with an airflow rate of 30 mL / min.

[0057] test: Al composite metal oxide 1.7 Ga 0.3 O3 at 655℃ was first tableted, then crushed and sieved to obtain uniformly sized oxide particles. 130 mg of these particles were weighed and loaded into the reactor, where propane dehydrogenation was carried out under atmospheric pressure in a continuous flow system equipped with a fixed-bed quartz tube reactor. Before the reaction, the catalyst was activated for 2 h at 500℃ and a helium flow rate of 50 mL / min. Then, propane was introduced into the reactor using nitrogen as a carrier gas and reacted at 550℃ for 180 min (propane / nitrogen = 1:9) at a total flow rate of 20 mL / min. After 35 min of reaction, the propane conversion was 54.6%, and the propylene selectivity was 87.3%.

[0058] MIL-53 (Al) 1.7 Ga 0.3 Al 1.7 Ga 0.3 O3@555℃, Al 1.7 Ga 0.3 O3@600℃ and Al 1.7 Ga 0.3 The XRD diffraction pattern of O3 at 655℃ is as follows: Figure 2 As shown. MIL-53 (Al) 1.7 Ga 0.3 Al 1.7 Ga 0.3 O3@555℃, Al 1.7 Ga 0.3 O3@600℃ and Al 1.7 Ga 0.3 O3@655℃ 27 Al solid NMR spectrum as shown Figure 6As shown. Al 1.7 Ga 0.3 O3@555℃, Al 1.7 Ga 0.3 O3@600℃ and Al 1.7 Ga 0.3 O3@655℃ 71 Ga solid NMR spectrum as shown in Figure 10 As shown. Al 1.7 Ga 0.3 O3@555℃, Al 1.7 Ga 0.3 O3@600℃ and Al 1.7 Ga 0.3 The catalytic activity of O3 at 655℃ for propane dehydrogenation is as follows: Figure 12 As shown.

[0059] Example 9 The propane dehydrogenation catalyst prepared using the porous composite metal oxide material derived from bimetallic MIL-53 is obtained by the following method: A2. A certain amount of Al 1.7 Ga 0.3 O3 was impregnated in 5 mL of chloroplatinic acid solution at 655℃, and then stirred at 60℃. Subsequently, it was calcined in a tube furnace at 500℃ in flowing air for 3 h to obtain the Pt-supported composite metal oxide Pt-Al. 1.7 Ga 0.3 O3@655℃ catalyst, with a Pt loading of 0.5 wt.%.

[0060] test: Pt-Al composite metal oxide loaded with Pt 1.7 Ga 0.3 O3 at 655℃ was first tableted, then crushed and sieved to obtain uniformly sized oxide particles, which were then loaded into a reactor. Propane dehydrogenation was then carried out under atmospheric pressure in a continuous flow system equipped with a fixed-bed quartz tube reactor. Before the reaction, the catalyst was activated for 2 h at 500℃ and a helium flow rate of 50 mL / min. Afterwards, propane was introduced into the reactor using nitrogen as a carrier gas and reacted at 550℃ for 180 min (propane / nitrogen = 1:9) at a total flow rate of 20 mL / min. At 35 min of reaction time, the propane conversion was 79.0%, and the propylene selectivity was 77.0%.

[0061] Pt-Al 1.7 Ga 0.3 O3@555℃, Pt-Al 1.7 Ga 0.3 O3@600℃ and Pt-Al1.7 Ga 0.3 The XRD diffraction pattern of O3 at 655℃ is as follows: Figure 3 As shown. Pt-Al 1.7 Ga 0.3 O3@555℃, Pt-Al 1.7 Ga 0.3 O3@600℃ and Pt-Al 1.7 Ga 0.3 O3@655℃ 27 Al solid NMR spectrum as shown Figure 7 As shown. Pt-Al 1.7 Ga 0.3 O3@555℃, Pt-Al 1.7 Ga 0.3 O3@600℃ and Pt-Al 1.7 Ga 0.3 The catalytic activity of O3 at 655℃ for propane dehydrogenation is as follows: Figure 13 As shown.

[0062] Non-preferred embodiment 10 The preparation method of the bimetallic MIL-53-derived porous composite metal oxide material includes the following steps: (1) Dissolve 42.5 mmol Al(NO3)3•9H2O, 7.5 mmol Ga(NO3)3•xH2O and 4.8 mmol H2BDC in 30 mL of water and stir until completely dissolved to obtain a clear solution; transfer the clear solution to a reaction vessel and seal it, place it in an oven at 200 °C for 72 h to crystallize, and then collect the product; (2) Dissolve the product from step (1) in 60 mL of DMF solvent, then transfer it to a reaction vessel and seal it. Place it in a 150 °C oven for 12 h, collect the product, and then wash it three times with DMF and methanol respectively to obtain bimetallic MIL-53 (Al 1.3 Ga 0.7 )sample; (3) The bimetallic MIL-53 sample prepared in step (2) was placed in a tube furnace as a precursor. The temperature was first increased to 555°C at a rate of 5°C / min under a nitrogen atmosphere and held for 3 hours. Then, it was calcined in flowing air for 7 hours. All airflow rates were 30 mL / min. After the tube furnace cooled to room temperature, the white powder product was collected, washed with ethanol, and dried under a nitrogen atmosphere to obtain the derivative of bimetallic MIL-53 (Al, Ga), namely the composite metal oxide Al. 1.7 Ga 0.3 O3@555℃#.

[0063] The propane dehydrogenation catalyst prepared using the porous composite metal oxide material derived from bimetallic MIL-53 is obtained by the following method: A1. The material obtained in step (3) is heated to 500℃ at a rate of 5℃ / min under a nitrogen atmosphere, then reduced by 10% H2 / N2 for 100min, then purged with nitrogen for 50min, and finally calcined in air for 3h to obtain the composite metal oxide catalyst Al. 1.7 Ga 0.3 O3@555℃#, the above airflow rate is 30mL / min.

[0064] test: Al composite metal oxide 1.7 Ga 0.3 O3 at 555℃ was first tableted, then crushed and sieved to obtain uniformly sized oxide particles, which were then loaded into a reactor. Propane dehydrogenation was then carried out under atmospheric pressure in a continuous flow system equipped with a fixed-bed quartz tube reactor. Before the reaction, the catalyst was activated for 2 h at 500℃ and a helium flow rate of 50 mL / min. Afterward, propane was introduced into the reactor using nitrogen as a carrier gas and reacted at 550℃ for 180 min (propane / nitrogen = 1:9), with a total flow rate of 20 mL / min. At 35 min of reaction time, the propane conversion was 32.2%, and the propylene selectivity was 87.7%.

[0065] Compared with Example 4, the excessively rapid heating rate in step (3) easily leads to the formation of gallium oxide crystal particles, and the subsequent direct hydrogen reduction-oxidation reduces the Ga content. IV The formation of Al reduces the catalyst's reactivity. 1.7 Ga 0.3 The XRD diffraction pattern of O3@555℃# is as follows: Figure 14 As shown, Al 1.7 Ga 0.3 O3@555℃# 71 Ga solid NMR spectrum as shown in Figure 15 As shown in the figure, large gallium oxide characteristic peaks appear on the catalyst material, and from Ga... IV and Ga VI From the relative height, we can know that Ga IV The content has decreased.

[0066] Non-preferred embodiment 11 The preparation method of the bimetallic MIL-53-derived porous composite metal oxide material includes the following steps: (1) Dissolve 42.5 mmol Al(NO3)3•9H2O, 7.5 mmol Ga(NO3)3•xH2O and 4.8 mmol H2BDC in 30 mL of water and stir until completely dissolved to obtain a clear solution; transfer the clear solution to a reaction vessel and seal it, place it in an oven at 200 °C for 72 h to crystallize, and then collect the product; (2) Dissolve the product from step (1) in 60 mL of DMF solvent, then transfer it to a reaction vessel and seal it. Place it in a 150 °C oven for 12 h, collect the product, and then wash it three times with DMF and methanol respectively to obtain bimetallic MIL-53 (Al 1.7 Ga 0.3 )sample; (3) The bimetallic MIL-53 sample prepared in step (2) was placed in a tube furnace as a precursor. The temperature was first increased to 350°C at a rate of 2°C / min under a nitrogen atmosphere, then increased to 555°C at a rate of 5°C / min, and held for 3 hours. Air was gradually injected into the inert atmosphere, increasing its concentration linearly or stepwise from 0% to 100% within 2 hours. The furnace was then calcined in flowing air for 7 hours, with the airflow rate being 30 mL / min. After the tube furnace cooled to room temperature, the white powder product was collected, washed with ethanol, and dried under a nitrogen atmosphere to obtain the derivative of bimetallic MIL-53 (Al, Ga), namely the composite metal oxide Al. 1.7 Ga 0.3 O3@555℃##.

[0067] The propane dehydrogenation catalyst prepared using the porous composite metal oxide material derived from bimetallic MIL-53 is obtained by the following method: A1. The material obtained in step (3) is heated to 500℃ at a rate of 5℃ / min under a nitrogen atmosphere, then reduced by 10% H2 / N2 for 100min, then purged with nitrogen for 50min, and finally calcined in air for 3h to obtain the composite metal oxide catalyst Al. 1.7 Ga 0.3 O3@555℃##, the above airflow rate is 30mL / min.

[0068] test: Al composite metal oxide 1.7 Ga 0.3O3 at 555℃ was first tableted, then crushed and sieved to obtain uniformly sized oxide particles, which were then loaded into a reactor. Propane dehydrogenation was then carried out under atmospheric pressure in a continuous flow system equipped with a fixed-bed quartz tube reactor. Before the reaction, the catalyst was activated for 2 h at 500℃ and a helium flow rate of 50 mL / min. Afterwards, propane was introduced into the reactor using nitrogen as a carrier gas and reacted at 550℃ for 180 min (propane / nitrogen = 1:9) at a total flow rate of 20 mL / min. At 35 min of reaction time, the propane conversion was 41.5%, and the propylene selectivity was 89.2%.

[0069] Compared to Example 4, direct hydrogen reduction-oxidation reduces Ga content. IV The formation of Al reduces the reaction activity of the catalyst. 1.7 Ga 0.3 The XRD diffraction pattern of O3@555℃## is as follows Figure 16 As shown, Al 1.7 Ga 0.3 O3@555℃## 71 Ga solid NMR spectrum as shown in Figure 17 As shown in the figure, large gallium oxide characteristic peaks appear on the catalyst material, and from Ga... IV and Ga VI From the relative height, we can know that Ga IV The content has decreased.

[0070] Non-preferred embodiment 12 The preparation method of the bimetallic MIL-53-derived porous composite metal oxide material includes the following steps: (1) Dissolve 42.5 mmol Al(NO3)3•9H2O, 7.5 mmol Ga(NO3)3•xH2O and 4.8 mmol H2BDC in 30 mL of water and stir until completely dissolved to obtain a clear solution; transfer the clear solution to a reaction vessel and seal it, place it in an oven at 200 °C for 72 h to crystallize, and then collect the product; (2) Dissolve the product from step (1) in 60 mL of DMF solvent, then transfer it to a reaction vessel and seal it. Place it in a 150 °C oven for 12 h, collect the product, and then wash it three times with DMF and methanol respectively to obtain bimetallic MIL-53 (Al 1.7 Ga 0.3 )sample; (3) The bimetallic MIL-53 sample prepared in step (2) was placed in a tube furnace as a precursor. The temperature was first increased to 555°C at a rate of 5°C / min under a nitrogen atmosphere and held for 3 hours. Then, it was calcined in flowing air for 7 hours. All airflow rates were 30 mL / min. After the tube furnace cooled to room temperature, the white powder product was collected, washed with ethanol, and dried under a nitrogen atmosphere to obtain the derivative of bimetallic MIL-53 (Al, Ga), namely the composite metal oxide Al. 1.7 Ga 0.3 O3@555℃###.

[0071] The propane dehydrogenation catalyst prepared using the porous composite metal oxide material derived from bimetallic MIL-53 is obtained by the following method: A1. The material obtained in step (3) is heated to 500℃ at a rate of 5℃ / min under a nitrogen atmosphere, and alternating reducing atmosphere pulses are performed: 10% H2 / N2 is introduced for 20min, then switched to N2 for 10min, and this process is repeated for 5 cycles. Finally, it is calcined in air for 3h to obtain the composite metal oxide catalyst Al. 1.7 Ga 0.3 O3@555℃###, the above airflow rate is 30mL / min.

[0072] test: Al composite metal oxide 1.7 Ga 0.3 O3 at 555℃ was first tableted, then crushed and sieved to obtain uniformly sized oxide particles, which were then loaded into a reactor. Propane dehydrogenation was then carried out under atmospheric pressure in a continuous flow system equipped with a fixed-bed quartz tube reactor. Before the reaction, the catalyst was activated for 2 h at 500℃ and a helium flow rate of 50 mL / min. Afterwards, propane was introduced into the reactor using nitrogen as a carrier gas and reacted at 550℃ for 180 min (propane / nitrogen = 1:9), with a total flow rate of 20 mL / min. At 35 min of reaction time, the propane conversion was 36.3%, and the propylene selectivity was 89.7%.

[0073] Compared with Example 4, the excessively rapid heating rate in step (3) can easily lead to the formation of gallium oxide crystal particles, which will reduce the reaction activity of the catalyst. 1.7 Ga 0.3 The XRD diffraction pattern of O3@555℃### is as follows Figure 18 As shown, Al 1.7 Ga 0.3 O3@555℃### 71 Ga solid NMR spectrum as shown in Figure 19As shown in the figure, large gallium oxide characteristic peaks appear on the catalyst material, and from Ga... IV and Ga VI From the relative height, we can know that Ga IV The content has decreased.

[0074] Comparative Example 1 The preparation method of the bimetallic MIL-53-derived porous composite metal oxide material includes the following steps: (1) Dissolve 42.5 mmol Al(NO3)3•9H2O, 7.5 mmol Ga(NO3)3•xH2O and 4.8 mmol H2BDC in 30 mL of water and stir until completely dissolved to obtain a clear solution; transfer the clear solution to a reaction vessel and seal it, place it in an oven at 200 °C for 72 h to crystallize, and then collect the product; (2) Dissolve the product from step (1) in 60 mL of DMF solvent, then transfer it to a reaction vessel and seal it. Place it in a 150 °C oven for 12 h, collect the product, and then wash it three times with DMF and methanol respectively to obtain bimetallic MIL-53 (Al 1.7 Ga 0.3 )sample; (3) The bimetallic MIL-53 sample prepared in step (2) was placed in a tube furnace as a precursor and calcined at 555°C at a rate of 5°C / min under air atmosphere for 7 hours. The gas flow rate was 30 mL / min. After the tube furnace cooled to room temperature, the white powder product was collected, washed with ethanol, and dried under nitrogen atmosphere to obtain the derivative of bimetallic MIL-53 (Al, Ga), namely the composite metal oxide Al. 1.7 Ga 0.3 O3@555℃####.

[0075] The propane dehydrogenation catalyst prepared using the porous composite metal oxide material derived from bimetallic MIL-53 is obtained by the following method: A1. The material obtained in step (3) is heated to 500°C in air at a rate of 5°C / min and calcined for 3 hours to obtain the composite metal oxide catalyst Al. 1.7 Ga 0.3 O3@555℃####, the above airflow rate is 30mL / min.

[0076] test: Al composite metal oxide 1.7 Ga 0.3O3 at 555℃ was first tableted, then crushed and sieved to obtain uniformly sized oxide particles, which were then loaded into a reactor. Propane dehydrogenation was then carried out under atmospheric pressure in a continuous flow system equipped with a fixed-bed quartz tube reactor. Before the reaction, the catalyst was activated for 2 h at 500℃ and a helium flow rate of 50 mL / min. Afterwards, propane was introduced into the reactor using nitrogen as a carrier gas and reacted at 550℃ for 180 min (propane / nitrogen = 1:9), with a total flow rate of 20 mL / min. At 35 min of reaction time, the propane conversion was 24.5%, and the propylene selectivity was 87.5%.

[0077] Compared with Example 4, the heating rate in step (3) is too fast, which easily leads to the formation of gallium oxide crystal particles; in addition, without hydrogen reduction, calcination is carried out directly in the air, which not only promotes the formation of large gallium oxide particles, but also reduces the content of tetracoordinated gallium, thereby greatly reducing the reaction activity of the catalyst. 1.7 Ga 0.3 The XRD diffraction pattern of O3@555℃### is as follows Figure 20 As shown, Al 1.7 Ga 0.3 O3@555℃### 71 Ga solid NMR spectrum as shown in Figure 21 As shown, Al 1.7 Ga 0.3 The catalytic activity of O3 at 555℃ for propane dehydrogenation is as follows: Figure 22 As shown in the figure, large gallium oxide characteristic peaks appear on the catalyst material, and from Ga... IV and Ga VI From the relative height, we can know that Ga IV The content has decreased.

Claims

1. A method for preparing a porous composite metal oxide material derived from bimetallic MIL-53, characterized in that, Includes the following steps: (1) Aluminum salt, gallium salt and 1,4-terephthalic acid are subjected to hydrothermal reaction to obtain hydrothermal reaction products; wherein the molar ratio of aluminum ions to gallium ions is 13:7 to 17:

3. (2) The hydrothermal reaction product is subjected to solvothermal treatment, followed by solvent exchange washing to obtain the bimetallic MIL-53 precursor; (3) The bimetallic MIL-53 precursor is subjected to stepwise dynamic atmosphere calcination, wherein the calcination includes: (a) Under an inert atmosphere, the precursor is heated to 555°C to 655°C and subjected to a first stage of heat preservation. (b) Then, the atmosphere is switched to an oxidizing atmosphere and a second stage of heat preservation is carried out to obtain a porous composite metal oxide material.

2. The method for preparing the bimetallic MIL-53-derived porous composite metal oxide material according to claim 1, characterized in that, The solvent used in the solvent heat treatment in step (2) is N,N-dimethylformamide.

3. The method for preparing the bimetallic MIL-53-derived porous composite metal oxide material according to claim 1, characterized in that, The solvent exchange washing in step (2) is performed using N,N-dimethylformamide and methanol.

4. The method for preparing the bimetallic MIL-53-derived porous composite metal oxide material according to claim 1, characterized in that, After step (3), a post-treatment step of washing and drying the porous composite metal oxide material is also included.

5. The method for preparing the bimetallic MIL-53-derived porous composite metal oxide material according to claim 1, characterized in that, Step (a) specifically involves raising the temperature to 350-450℃ at a rate of 2-3℃ / min, then raising it to 555-655℃ at a rate of 5-8℃ / min, and then performing the first stage of heat preservation.

6. The method for preparing the bimetallic MIL-53-derived porous composite metal oxide material according to claim 5, characterized in that, Step (b) specifically involves gradually injecting an oxidizing gas into an inert atmosphere, increasing its concentration linearly or stepwise from 0% to 100% over 0.5-2 hours, followed by a second stage of heat preservation in a pure oxidizing atmosphere.

7. A porous composite metal oxide material derived from bimetallic MIL-53, characterized in that, It is prepared by any one of the preparation methods described in claims 1 to 6.

8. A propane dehydrogenation catalyst prepared using the porous composite metal oxide material derived from the bimetallic MIL-53 as described in claim 7, characterized in that, The propane dehydrogenation catalyst was prepared by subjecting a porous composite metal oxide material derived from bimetallic MIL-53 to reduction-oxidation heat treatment or by loading metal Pt.

9. The propane dehydrogenation catalyst according to claim 8, characterized in that, The reduction-oxidation heat treatment specifically involves alternating pulses of reducing atmosphere and pulses of inert atmosphere at the heat treatment temperature, followed by a final heat treatment in an oxidizing atmosphere.

10. The application of a propane dehydrogenation catalyst according to any one of claims 8-9, characterized in that, The propane dehydrogenation catalyst is used to catalyze the propane dehydrogenation reaction. Before use, the propane dehydrogenation catalyst needs to be activated by heating in an inert atmosphere.

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