Biomass fluidized bed pyrolysis hydrogen production method and system based on MOF in-situ catalysis

Abstract

The invention discloses a biomass fluidized bed pyrolysis hydrogen production method and system based on MOF in-situ catalysis, and belongs to the technical field of crossing of biomass energy conversion technology and catalytic materials. According to the method, through a dynamic strategy of feeding mixing and in-situ generation, active center construction of the catalyst and pyrolysis reaction of biomass are synchronously completed in the same reactor, the technological process is greatly simplified, the equipment investment and the operation energy consumption are reduced, the reduction atmosphere generated by biomass pyrolysis and in-situ oxidation of the aluminum powder are utilized, and the catalytic activity of the catalyst is improved. A composite catalytic system is constructed in real time on a reaction site, and in-situ generated metal nanoparticles are extremely high in dispersity and are protected by a carbon layer and an aluminum oxide carrier, so that metal sintering and carbon deposition inactivation are effectively inhibited, and the catalytic life is remarkably prolonged.

Description

Technical Field

[0001] This invention belongs to the interdisciplinary field of biomass energy conversion technology and catalytic materials, and particularly relates to a method and system for producing hydrogen from biomass fluidized bed pyrolysis based on MOF in-situ catalysis. Background Technology

[0002] With the increasing global demand for clean and sustainable energy, hydrogen, as a zero-carbon energy carrier, has become a research hotspot in terms of its development and utilization technology. Biomass energy is valuable due to its renewability, abundant reserves (approximately 3.5 billion tons of usable reserves annually in my country), and carbon neutrality. Biomass pyrolysis hydrogen production technology can convert waste biomass resources into high-value-added hydrogen, turning waste into treasure and offering significant environmental and economic benefits.

[0003] Traditional biomass pyrolysis technology faces two major challenges: the high tar content produced during pyrolysis is prone to condensation, clogging pipelines, corroding equipment, and reducing system efficiency; the yield and selectivity of the target product hydrogen are generally low, and the pyrolysis gas contains a large amount of CO, CO2 and other gases, resulting in high purification costs. To solve these problems, introducing a catalyst is key.

[0004] Current research primarily employs transition metal catalysts such as nickel-based and cobalt-based catalysts to enhance hydrogen yield through catalytic tar reforming and water-gas shift reactions. However, traditional catalysts are prone to rapid deactivation in high-temperature fluidized bed environments due to sintering and carbon deposition, and metal particles are easily agglomerated, leading to a reduction in active sites and a short catalytic lifetime. Metal-organic frameworks (MOFs) are a new class of porous crystalline materials. Among them, zeolite imidazole ester frameworks (ZIFs), such as ZIF-67 (Co-based) and ZIF-74 (Ni-based), are considered ideal catalyst precursors due to their high specific surface area, tunable pore structure, and good thermal stability. Existing technologies typically involve pre-calcining MOFs at high temperatures in a tube furnace to convert them into metal / carbon composite materials before using them as catalysts. This "preparation first, use later" strategy has limitations such as complex processes, high energy consumption, and the catalyst still facing mass transfer and stability issues during subsequent use. Summary of the Invention

[0005] The purpose of this invention is to address the problems of complex processes, high energy consumption, and mass transfer and stability issues that arise during the preparation of metal-organic framework materials, and to propose a method and system for hydrogen production from biomass fluidized bed pyrolysis based on MOF in-situ catalysis.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A biomass fluidized bed pyrolysis hydrogen production method based on MOF in-situ catalysis specifically includes the following steps:

[0008] S1. Preparation of metal-organic framework (MOF) materials: metal nitrate hydrate and organic ligands are dissolved in solvents respectively, mixed and stirred to react, and then filtered, washed and dried to obtain MOF crystal materials.

[0009] S2. MOF crystal material, cleaned aluminum powder and dried tobacco straw biomass raw material are directly physically mixed to obtain mixed feed;

[0010] S3. The mixed feed is fed into the fluidized bed pyrolysis furnace through the feeding system;

[0011] S4. Nitrogen gas is introduced. The nitrogen gas flows through the preheating system and is heated before entering the fluidized bed pyrolysis furnace to form a high-temperature inert fluidized atmosphere, and the material in the furnace undergoes catalytic pyrolysis reaction at 700°C.

[0012] S5. After the gas-solid mixture generated by pyrolysis is discharged from the fluidized bed pyrolysis furnace, it first enters the cyclone separator for gas-solid separation.

[0013] S6. The separated pyrolysis gas is then processed through cooling and purification units to obtain pure pyrolysis gas.

[0014] S7. Introduce the pure pyrolysis gas into a gas chromatograph for online component analysis and obtain product gas rich in H2.

[0015] As a further description of the above technical solution:

[0016] The MOF crystal material in S1 is selected from ZIF-67 crystal or ZIF-74 crystal;

[0017] When preparing ZIF-67 crystals, the metal nitrate hydrate is cobalt nitrate hexahydrate, the organic ligand is 2-methylimidazole, and the solvent is deionized water;

[0018] When preparing ZIF-74 crystals, the metal nitrate hydrate is nickel nitrate hexahydrate, the organic ligand is 2-methylimidazole, and the solvent is anhydrous methanol.

[0019] As a further description of the above technical solution:

[0020] The specific preparation process of the MOF material in S1 is as follows:

[0021] To prepare ZIF-67, cobalt nitrate hexahydrate and 2-methylimidazole were dissolved in deionized water at a molar ratio of 1:8. After mixing, the mixture was stirred at room temperature for 12 hours. The precipitate obtained by filtration was dried at 100°C for 12 hours and then ground to obtain purple Co-MOF powder.

[0022] To prepare ZIF-74, nickel nitrate hexahydrate and 2-methylimidazole were dissolved in anhydrous methanol at a molar ratio of 1:8. After mixing, the mixture was stirred at room temperature for 12 hours. The precipitate obtained by filtration was dried at 100°C for 12 hours and then ground to obtain blue Ni-MOF powder.

[0023] As a further description of the above technical solution:

[0024] The biomass raw material mentioned in S2 is tobacco straw;

[0025] The specific preparation process of the mixed feed includes:

[0026] The aluminum powder was washed with deionized water and then dried.

[0027] The tobacco stalks were dried at 105℃ for 12 hours and then preliminarily crushed.

[0028] The MOF material, aluminum powder, and tobacco straw powder are mixed in a predetermined mass ratio and then crushed and stirred.

[0029] As a further description of the above technical solution:

[0030] The predetermined mass ratio is for MOF materials:

[0031] Aluminum powder: Tobacco straw powder = (0.5~1.5):(0.5~1.5):6.

[0032] As a further description of the above technical solution:

[0033] After mixing in S2, the mixture is screened using one or more of the following mesh sizes: 40 mesh, 60 mesh, 80 mesh, and 100 mesh.

[0034] As a further description of the above technical solution:

[0035] The operating conditions for the catalytic pyrolysis reaction include:

[0036] The heating rate should be controlled at 5-15℃ / min;

[0037] The reaction temperature inside the fluidized bed pyrolysis furnace is controlled at 500-700℃;

[0038] The nitrogen gas used for fluidization is heated to 300-500°C by a preheating system before entering the reactor;

[0039] The total nitrogen flow rate is divided into two streams: one stream is used to maintain bed fluidization, and the other stream is used as a carrier gas to transport the feed.

[0040] As a further description of the above technical solution:

[0041] The volume fraction of hydrogen in the pyrolysis gas is not less than 40%.

[0042] As a further description of the above technical solution:

[0043] A biomass fluidized bed pyrolysis hydrogen production system based on MOF in-situ catalysis, the system being configured to include:

[0044] The console is used to centrally monitor and adjust the operating parameters of the entire system.

[0045] The feeding system is used to receive and convey a mixture of MOF material, aluminum powder and biomass raw materials;

[0046] A preheating system is used to preheat the introduced nitrogen gas;

[0047] A fluidized bed pyrolysis furnace, the inlet of which is connected to the feeding system and the preheating system respectively, is used for catalytic pyrolysis reaction;

[0048] A cyclone separator, whose inlet is connected to the gas outlet of the fluidized bed pyrolysis furnace, is used to separate solid particles from the pyrolysis gas;

[0049] The cooling and purification unit has its inlet connected to the gas outlet of the cyclone separator and is used to cool and dry the pyrolysis gas.

[0050] The gas chromatograph, whose inlet is connected to the gas outlet of the cooling and purification unit, is used for online component analysis of the purified pyrolysis gas.

[0051] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0052] 1. In this invention, through a dynamic strategy of feed mixing and in-situ generation, the construction of the active center of the catalyst and the pyrolysis reaction of biomass are completed simultaneously in the same reactor, which greatly simplifies the process and reduces equipment investment and operating energy consumption.

[0053] 2. In this invention, a composite catalytic system is constructed on-site in real time by utilizing the reducing atmosphere generated by biomass pyrolysis and the in-situ oxidation of aluminum powder. The metal nanoparticles generated in-situ have extremely high dispersion and are protected by both carbon layer and alumina support, effectively inhibiting metal sintering and carbon deposition deactivation, and significantly extending the catalytic life. Attached Figure Description

[0054] Figure 1 The manufacturing process of ZIF-67 and ZIF-74 of the present invention;

[0055] Figure 2 Experimental setup for the biomass pyrolysis system of this invention;

[0056] Figure 3The nitrogen adsorption-desorption test results of this invention are shown in BET.

[0057] Figure 4 Thermogravimetric analysis of (a) biomass, (b) ZIF-67 and (c) ZIF-74 for the present invention;

[0058] Figure 5 SEM analysis for this invention;

[0059] Figure 6 The gas yields of the present invention under different catalysts are shown in (a) ZIF-67 and (b) ZIF-74.

[0060] Figure 7 Raman analysis of ZIF-67 and ZIF-74 at different ratios according to the present invention;

[0061] Figure 8 XRD patterns of two MOFs after pyrolysis at different temperatures according to the present invention;

[0062] Figure 9 XPS analysis of ZIF-67 and ZIF-74 at different ratios according to the present invention;

[0063] Figure 10 XPS analysis of the Co peak at different ratios in this invention;

[0064] Figure 11 The infrared radiation is obtained after pyrolysis at different temperatures according to the present invention;

[0065] Figure 12 This is a principle analysis of the present invention. Detailed Implementation

[0066] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0067] Please see Figures 1-12 The present invention provides a technical solution:

[0068] A biomass fluidized bed pyrolysis hydrogen production method based on MOF in-situ catalysis specifically includes the following steps:

[0069] S1. Preparation of metal-organic framework (MOF) materials: metal nitrate hydrate and organic ligands are dissolved in solvents respectively, mixed and stirred to react, and then filtered, washed and dried to obtain MOF crystal materials.

[0070] S2. MOF crystal material, cleaned aluminum powder and dried tobacco straw biomass raw material are directly physically mixed to obtain mixed feed;

[0071] S3. The mixed feed is fed into the fluidized bed pyrolysis furnace through the feeding system;

[0072] S4. Nitrogen gas is introduced. The nitrogen gas flows through the preheating system and is heated before entering the fluidized bed pyrolysis furnace to form a high-temperature inert fluidized atmosphere, and the material in the furnace undergoes catalytic pyrolysis reaction at 700°C.

[0073] S5. After the gas-solid mixture generated by pyrolysis is discharged from the fluidized bed pyrolysis furnace, it first enters the cyclone separator for gas-solid separation.

[0074] S6. The separated pyrolysis gas is then processed through cooling and purification units to obtain pure pyrolysis gas.

[0075] S7. Introduce the pure pyrolysis gas into a gas chromatograph for online component analysis and obtain product gas rich in H2.

[0076] The MOF crystal material in S1 is selected from ZIF-67 crystal or ZIF-74 crystal;

[0077] When preparing ZIF-67 crystals, the metal nitrate hydrate is cobalt nitrate hexahydrate, the organic ligand is 2-methylimidazole, and the solvent is deionized water;

[0078] When preparing ZIF-74 crystals, the metal nitrate hydrate is nickel nitrate hexahydrate, the organic ligand is 2-methylimidazole, and the solvent is anhydrous methanol.

[0079] The specific preparation process of the MOF material in S1 is as follows:

[0080] To prepare ZIF-67, cobalt nitrate hexahydrate and 2-methylimidazole were dissolved in deionized water at a molar ratio of 1:8. After mixing, the mixture was stirred at room temperature for 12 hours. The precipitate obtained by filtration was dried at 100°C for 12 hours and then ground to obtain purple Co-MOF powder.

[0081] To prepare ZIF-74, nickel nitrate hexahydrate and 2-methylimidazole were dissolved in anhydrous methanol at a molar ratio of 1:8. After mixing, the mixture was stirred at room temperature for 12 hours. The precipitate obtained by filtration was dried at 100°C for 12 hours and then ground to obtain blue Ni-MOF powder.

[0082] The biomass raw material mentioned in S2 is tobacco straw;

[0083] The specific preparation process of the mixed feed includes:

[0084] The aluminum powder was washed with deionized water and then dried.

[0085] The tobacco stalks were dried at 105℃ for 12 hours and then preliminarily crushed.

[0086] The MOF material, aluminum powder, and tobacco straw powder are mixed in a predetermined mass ratio and then crushed and stirred.

[0087] The predetermined mass ratio is for MOF materials:

[0088] Aluminum powder: Tobacco straw powder = (0.5~1.5):(0.5~1.5):6;

[0089] After mixing in S2, the mixture is screened using one or more of the following mesh sizes: 40 mesh, 60 mesh, 80 mesh, and 100 mesh.

[0090] The operating conditions for the catalytic pyrolysis reaction include:

[0091] The heating rate should be controlled at 5-15℃ / min;

[0092] The reaction temperature inside the fluidized bed pyrolysis furnace is controlled at 500-700℃;

[0093] The nitrogen gas used for fluidization is heated to 300-500°C by a preheating system before entering the reactor;

[0094] The total nitrogen flow rate is divided into two streams: one stream is used to maintain bed fluidization, and the other stream is used as a carrier gas to transport the feed.

[0095] The volume fraction of hydrogen in the pyrolysis gas is not less than 40%.

[0096] A biomass fluidized bed pyrolysis hydrogen production system based on MOF in-situ catalysis, the system being configured to include:

[0097] The console is used to centrally monitor and adjust the operating parameters of the entire system.

[0098] The feeding system is used to receive and convey a mixture of MOF material, aluminum powder and biomass raw materials;

[0099] A preheating system is used to preheat the introduced nitrogen gas;

[0100] A fluidized bed pyrolysis furnace, the inlet of which is connected to the feeding system and the preheating system respectively, is used for catalytic pyrolysis reaction;

[0101] A cyclone separator, whose inlet is connected to the gas outlet of the fluidized bed pyrolysis furnace, is used to separate solid particles from the pyrolysis gas;

[0102] The cooling and purification unit has its inlet connected to the gas outlet of the cyclone separator and is used to cool and dry the pyrolysis gas.

[0103] The gas chromatograph, whose inlet is connected to the gas outlet of the cooling and purification unit, is used for online component analysis of the purified pyrolysis gas.

[0104] Experimental Example 1: Customized Preparation and Characterization of MOF Materials

[0105] Synthesis and characterization of ZIF-67: 5.82 g of cobalt nitrate hexahydrate and 15.38 g of 2-methylimidazole (molar ratio 1:8) were accurately weighed and dissolved separately in 200 ml of deionized water. The mixture was stirred at room temperature for 12 hours. After filtration, drying at 100 °C, and grinding, a purple ZIF-67 powder was obtained. Characterization confirmed that: XRD showed characteristic peaks at 7.3 °C, 10.3 °C, and 12.7 °C; TGA showed ligand cleavage at 200-300 °C and a characteristic exothermic peak at 620 °C; SEM showed that it was composed of petal-shaped microspheres assembled from nanosheets; XPS showed that the Co2p3 / 2 binding energy was ~780.0 eV.

[0106] Synthesis and characterization of ZIF-74: The method was the same as that for ZIF-67, but nickel nitrate hexahydrate was used instead of cobalt salt, and anhydrous methanol was used instead of deionized water to obtain a blue ZIF-74 powder. Characterization confirmed that XRD showed characteristic peaks at 7.5°, 11.2°, and 13.8°; TGA showed rapid weight loss at 200-300℃ and an exothermic peak at 293℃; SEM showed that it was an aggregate of nanoneedles in the shape of sea urchin microspheres; XPS showed that the Ni2p3 / 2 binding energy was ~905.0 eV.

[0107] Experimental Example 2: Hydrogen Production and Performance Verification via Pyrolysis in Fluidized Bed System

[0108] Material preparation: The ZIF-67 obtained in Example 1, the cleaned aluminum powder, and the pretreated tobacco straw were mixed in a mass ratio of 1:1:4.

[0109] System operation: Feed 30g of mixed feed into the fluidized bed system. Introduce nitrogen (total flow rate 8L / min, part of which is preheated to 400℃), and heat to 700℃ (i.e., 973K) at a rate of 10℃ / min, and react for 30 minutes.

[0110] Results and Analysis: Online gas chromatography analysis showed that the hydrogen gas fraction in the pyrolysis gas reached 52%. Simultaneously, XRD analysis of the pyrolysis slag revealed diffraction peaks for metallic Co and Al2O3, confirming that MOF and aluminum powder were successfully converted in situ into the target catalytic active phase during the reaction.

[0111] In summary, this application innovatively focuses on tobacco straw, a unique agricultural waste characterized by high yield and low utilization rate, and makes breakthroughs in key issues of existing research, establishing a biomass pyrolysis fluidized bed experimental platform. Flaky Co-MOFs and needle-like Ni-MOFs were prepared, and characterization techniques revealed the modifying effect of alkali metal migration on the electronic structure of the catalysts. A multidimensional optimization model for tobacco leaf components, MOF ratios, and pyrolysis parameters was proposed. This design utilizes the intermetallic electron transfer effect to improve hydrogen production efficiency. This comprehensive approach of "catalytic innovation and optimization" provides a new technical pathway for efficient hydrogen production from nitrogen-rich biomass, promoting the value-added processing of agricultural waste and the development of clean energy.

[0112] In this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more unless otherwise explicitly defined. The terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; "linking" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0113] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for producing hydrogen from biomass via fluidized bed pyrolysis based on MOF in-situ catalysis, characterized in that, Specifically, the following steps are included: S1. Preparation of metal-organic framework (MOF) materials: metal nitrate hydrate and organic ligands are dissolved in solvents respectively, mixed and stirred to react, and then filtered, washed and dried to obtain MOF crystal materials. S2. MOF crystal material, cleaned aluminum powder and dried tobacco straw biomass raw material are directly physically mixed to obtain mixed feed; S3. The mixed feed is fed into the fluidized bed pyrolysis furnace through the feeding system; S4. Nitrogen gas is introduced. The nitrogen gas flows through the preheating system and is heated before entering the fluidized bed pyrolysis furnace to form a high-temperature inert fluidized atmosphere, and the material in the furnace undergoes catalytic pyrolysis reaction at 700°C. S5. After the gas-solid mixture generated by pyrolysis is discharged from the fluidized bed pyrolysis furnace, it first enters the cyclone separator for gas-solid separation. S6. The separated pyrolysis gas is then processed through cooling and purification units to obtain pure pyrolysis gas. S7. Introduce the pure pyrolysis gas into a gas chromatograph for online component analysis and obtain product gas rich in H2.

2. The method for producing hydrogen from biomass via fluidized bed pyrolysis based on MOF in-situ catalysis according to claim 1, characterized in that, The MOF crystal material in S1 is selected from ZIF-67 crystal or ZIF-74 crystal; When preparing ZIF-67 crystals, the metal nitrate hydrate is cobalt nitrate hexahydrate, the organic ligand is 2-methylimidazole, and the solvent is deionized water; When preparing ZIF-74 crystals, the metal nitrate hydrate is nickel nitrate hexahydrate, the organic ligand is 2-methylimidazole, and the solvent is anhydrous methanol.

3. The method for producing hydrogen from biomass via fluidized bed pyrolysis based on MOF in-situ catalysis according to claim 2, characterized in that, The specific preparation process of the MOF material in S1 is as follows: To prepare ZIF-67, cobalt nitrate hexahydrate and 2-methylimidazole were dissolved in deionized water at a molar ratio of 1:

8. After mixing, the mixture was stirred at room temperature for 12 hours. The precipitate obtained by filtration was dried at 100°C for 12 hours and then ground to obtain purple Co-MOF powder. To prepare ZIF-74, nickel nitrate hexahydrate and 2-methylimidazole were dissolved in anhydrous methanol at a molar ratio of 1:

8. After mixing, the mixture was stirred at room temperature for 12 hours. The precipitate obtained by filtration was dried at 100°C for 12 hours and then ground to obtain blue Ni-MOF powder.

4. The method for producing hydrogen from biomass via fluidized bed pyrolysis based on MOF in-situ catalysis according to claim 1, characterized in that, The biomass raw material mentioned in S2 is tobacco straw; The specific preparation process of the mixed feed includes: The aluminum powder was washed with deionized water and then dried. The tobacco stalks were dried at 105℃ for 12 hours and then preliminarily crushed. The MOF material, aluminum powder, and tobacco straw powder are mixed in a predetermined mass ratio and then crushed and stirred.

5. The method for producing hydrogen from biomass via fluidized bed pyrolysis based on MOF in-situ catalysis according to claim 4, characterized in that, The predetermined mass ratio is for MOF materials: Aluminum powder: Tobacco straw powder = (0.5~1.5):(0.5~1.5):

6.

6. The method for producing hydrogen from biomass via fluidized bed pyrolysis based on MOF in-situ catalysis according to claim 4, characterized in that, After mixing in S2, the mixture is screened using one or more of the following mesh sizes: 40 mesh, 60 mesh, 80 mesh, and 100 mesh.

7. The method for producing hydrogen from biomass via fluidized bed pyrolysis based on MOF in-situ catalysis according to claim 1, characterized in that, The operating conditions for the catalytic pyrolysis reaction include: The heating rate should be controlled at 5-15℃ / min; The reaction temperature inside the fluidized bed pyrolysis furnace is controlled at 500-700℃; The nitrogen gas used for fluidization is heated to 300-500°C by a preheating system before entering the reactor; The total nitrogen flow rate is divided into two streams: one stream is used to maintain bed fluidization, and the other stream is used as a carrier gas to transport the feed.

8. A method for producing hydrogen from biomass via fluidized bed pyrolysis based on MOF in-situ catalysis according to any one of claims 1-7, characterized in that, The volume fraction of hydrogen in the pure pyrolysis gas is not less than 40%.

9. A biomass fluidized bed pyrolysis hydrogen production system based on MOF in-situ catalysis, applied to the biomass fluidized bed pyrolysis hydrogen production method based on MOF in-situ catalysis according to any one of claims 1-8, wherein the system is configured to include: The console is used to centrally monitor and adjust the operating parameters of the entire system. The feeding system is used to receive and convey a mixture of MOF material, aluminum powder and biomass raw materials; A preheating system is used to preheat the introduced nitrogen gas; A fluidized bed pyrolysis furnace, the inlet of which is connected to the feeding system and the preheating system respectively, is used for catalytic pyrolysis reaction; A cyclone separator, whose inlet is connected to the gas outlet of the fluidized bed pyrolysis furnace, is used to separate solid particles from the pyrolysis gas; The cooling and purification unit has its inlet connected to the gas outlet of the cyclone separator and is used to cool and dry the pyrolysis gas. The gas chromatograph, whose inlet is connected to the gas outlet of the cooling and purification unit, is used for online component analysis of the purified pyrolysis gas.

10. A MOF catalytic material for use in the method of claim 1, characterized in that, The MOF material is ZIF-67 or ZIF-74: The ZIF-67 is characterized by the following features: XRD characteristic diffraction peaks located at 2θ = 7.3°, 10.3°, and 12.7°; and the binding energy of Co2p3 / 2 located at ~780.0 eV. The microstructure is a petal-shaped microsphere structure assembled from nanosheets; The ZIF-74 is characterized by the following features: XRD characteristic diffraction peaks located at 2θ = 7.5°, 11.2°, and 13.8°; and the binding energy of Ni2p3 / 2 located at ~905.0 eV. The microstructure is a sea urchin-like microsphere structure formed by the aggregation of nanoneedles.

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