Preparation method and application of In2O3 catalyst with epitaxial growth structure
By epitaxially growing In MOF on the surface of Zn MOF to form Zn MOF@In MOF hybrid material, the problems of low catalytic activity and poor dispersion of noble metal particles in CO2 reduction reaction of In2O3 catalyst are solved, and the high efficiency of CO2 reduction performance and stability are improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BOHAI UNIV
- Filing Date
- 2025-12-31
- Publication Date
- 2026-04-10
AI Technical Summary
Existing In2O3 catalysts suffer from low catalytic activity, high recombination rate of photogenerated electron-hole pairs, and large and poorly dispersed noble metal particles in CO2 reduction reactions. MOF-derived metal oxide catalysts are difficult to precisely control in terms of component ratio and distribution.
Zn MOF was prepared as a substrate using a solvothermal method. Zn MOF@In MOF hybrid material was formed on its surface by epitaxial growth technology. Combined with a reasonable calcination process, an In2O3 catalyst with an epitaxial growth structure was formed, which ensured that the metal nodes were uniformly dispersed and formed oxygen vacancies, thus preserving the porous structure and high specific surface area of the MOF.
This method achieves highly efficient CO2 reduction performance of the catalyst, improves catalytic activity and stability, and increases catalytic efficiency several times over compared to conventional methods, significantly improving CO2 conversion rate and methanol selectivity.
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Figure CN121819804A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of catalyst technology, and more specifically, to an In2O3 catalyst with an epitaxial growth structure, its preparation method, and its application. Background Technology
[0002] Indium oxide (In₂O₃), as an n-type semiconductor, has attracted widespread attention in the field of catalysis due to its excellent stability, high product selectivity, and good photoresponse performance. Especially in the CO₂ reduction reaction, the oxygen vacancies and numerous hydroxyl groups on the In₂O₃ surface can effectively regulate electrons and generate adsorption sites, giving it excellent CO₂ adsorption and activation capabilities.
[0003] However, pure-phase In₂O₃ has significant drawbacks, such as low catalytic activity and high recombination rate of photogenerated electron-hole pairs. Focusing on improving the dispersibility of In₂O₃, increasing oxygen vacancy content, enhancing hydrogen dissociation, and expanding the photoresponse range, the core optimization methods can be summarized into two categories: First, loading In₂O₃ onto a support (such as ZrO₂, ZnO, TiO₂, or Al₂O₃) to improve its dispersibility and promote oxygen vacancy formation, thereby optimizing catalytic performance. Second, doping In₂O₃ with elements such as C, N, Ga, Ag, Ni, Pd, and Rh. This method can adjust the electronic band structure, expand the photoresponse range, and promote electron-hole pair separation, thus improving the catalytic CO₂ reduction efficiency. Simultaneously, the introduction of metal elements can enhance the adsorption and dissociation of H₂. From the perspective of catalytic efficiency and stability, there is still considerable room for performance improvement even with the simple application of these two optimization methods.
[0004] Metal-organic frameworks (MOFs) have attracted widespread research interest in heterogeneous catalysis due to their tunable structure and composition, high specific surface area, porosity, and abundant unsaturated metal sites. MOF-derived metal oxides, in particular, typically inherit the high porosity and tunable morphology of the parent MOF material, making them promising for catalysis. Some researchers have used In MOFs as supports to impregnate noble metals, demonstrating good performance in catalytic CO2 conversion. However, the noble metal precursors are susceptible to the influence of MOF surface charge distribution and pore structure, leading to uneven adsorption or aggregation, resulting in large and poorly dispersed noble metal particles. Heterogeneous MOFs are also a common application, but some researchers have found that the simultaneous mixing and reaction of two or more metals with organic ligands causes interference between the nucleation and growth processes of different MOFs, making it difficult to form a clear interfacial crystalline phase. Furthermore, the different growth rates of different MOFs make it difficult to precisely control the proportion and distribution of each component.
[0005] How to effectively utilize the unique structural advantages of MOFs while improving the catalytic activity of metal oxides is an urgent problem to be solved in the field of MOF-derived metal oxide catalysts. Summary of the Invention
[0006] This invention designs and develops an In2O3 catalyst with an epitaxial growth structure. It uses ZnMOF prepared by solvothermal means as the host and grows In MOF guest on its surface to form a Zn MOF@In MOF hybrid material. Compared with existing methods for optimizing the performance of In2O3 catalysts such as loading and hybridization, the uniformly dispersed metal nodes in the MOF structure under high temperature and inert atmosphere will induce a large number of oxygen vacancies with the decomposition of organic ligands. At the same time, it inherits the porous structure and high specific surface area of MOF, and the small-sized metal oxide grain boundaries are more conducive to the formation and distribution of oxygen vacancies.
[0007] This invention also provides a method for preparing an In2O3 catalyst with an epitaxial growth structure. By controlling the dosage, synthesis temperature and time, and combining a reasonable degree of calcination process, a Zn MOF@In MOF hybrid material is formed. The process is simple and the conditions are controllable.
[0008] On the other hand, another objective of this invention is to provide applications of In2O3 catalysts with epitaxial growth structures, which have broad application prospects in catalytic functions such as carbon dioxide hydrogenation reduction.
[0009] The technical solution provided by this invention is as follows:
[0010] An In2O3 catalyst with an epitaxial growth structure includes a metal-organic framework precursor A and an indium-based metal-organic framework B. The indium-based metal-organic framework B is epitaxially grown on the metal-organic framework precursor A, and then calcined to obtain the In2O3-based catalyst.
[0011] Preferably, the method for preparing the In2O3 catalyst with the epitaxial growth structure includes:
[0012] Step 1: Dissolve a certain mass of soluble metal salt and terephthalic acid BDC in N,N-dimethylformamide (DMF) solution. Transfer the mixed solution to a polytetrafluoroethylene (PTFE) reactor liner and react for several hours. Centrifuge to collect the precipitate, wash several times with DMF and ethanol, and dry to obtain metal-organic framework precursor A.
[0013] Step 2: Take a certain mass of soluble indium salt, polyvinylpyrrolidone (PVP), and the metal-organic framework precursor A prepared in Step 1, disperse them in DMF solution, add a certain mass of DMF solution containing BDC, stir thoroughly, transfer the resulting suspension to a hydrothermal reactor and react for several hours, centrifuge to collect the precipitate, wash with DMF and ethanol several times, and dry to obtain indium-based metal-organic framework B epitaxially grown on metal-organic framework precursor A.
[0014] Step 3: The In-based metal-organic framework B epitaxially grown on metal-organic framework A is calcined in a tube furnace.
[0015] Preferably, the metal center of the metal-organic framework precursor A is a heterometallic metal with indium.
[0016] Preferably, the metal center of the metal-organic framework A is Zn, Ga, Cu, or Mg.
[0017] Preferably, the soluble metal salt and soluble indium salt are Zn(NO3)2·6H2O, Ga(NO3)3·4H2O, Cu(NO3)2·3H2O, Mg(NO3)2·6H2O, and In(NO3)3·4H2O.
[0018] Preferably, the polyvinylpyrrolidone (PVP) has a relative molecular mass of 58,000.
[0019] Preferably, the synthesis temperature range of the metal-organic framework A and the In2O3 catalyst with epitaxial growth structure is 100-140℃, and the reaction time is 6-48h.
[0020] Preferably, the roasting temperature of the roasting treatment is 400-600℃, the roasting time is 1-6h, and the inert atmosphere gas is N2 or Ar.
[0021] Preferably, in step one, 1 mmol of a soluble metal salt is dissolved in 15 mL of DMF, and then 15 mL of DMF solution containing 0.166 g BDC is added. After stirring for 30 min to ensure thorough mixing, the mixed solution is transferred to a 100 mL polytetrafluoroethylene reactor liner and reacted in an oven at 120 °C for 24 h. The precipitate is collected by centrifugation, washed multiple times with DMF and ethanol, and dried to obtain metal-organic framework precursor A.
[0022] Preferably, in step two, 1.492g In(NO3)3·4H2O, 0.58g PVP, and a certain mass of metal-organic framework precursor A are then dispersed in 30mL DMF solution. 30mL of DMF solution containing 0.664g BDC is added, and after thorough stirring, the resulting suspension is transferred to a 100mL polytetrafluoroethylene reactor liner and reacted in an oven at 120℃ for 12h. The precipitate is collected by centrifugation, washed multiple times with DMF and ethanol, and dried to obtain an indium-based metal-organic framework B epitaxially grown on metal-organic framework A.
[0023] Preferably, the mass fraction of metal in the In2O3 catalyst with epitaxial growth structure is 5-50%, and the mass of added metal-organic framework precursor A is 0.1-2.5g.
[0024] Preferably, the roasting process in step three is roasting in a tube furnace at 500°C under an Ar atmosphere for 2 hours.
[0025] Preferably, the In2O3 catalyst with an epitaxial growth structure, or the In2O3 catalyst with an epitaxial growth structure prepared by the preparation method of the In2O3 catalyst with an epitaxial growth structure, is used in CO2 heating catalytic reduction reaction, CO2 photocatalytic reduction reaction, or CO2 electrocatalytic reduction reaction.
[0026] More preferably, it is used in the CO2 hydrogenation reduction reaction to prepare methanol or CO. 0.15g of catalyst and 0.15g of quartz sand are placed in a quartz reaction tube of a fixed-bed reactor, and N2 is introduced into it. Activation is carried out for 1 hour at atmospheric pressure and 200℃. The temperature is then increased to the reaction temperature of 260℃, irradiated with a 300W xenon lamp, and a mixed gas of CO2, H2, and N2 (feed ratio 1:3:1) is introduced. The pressure is increased to 3MPa, and the reaction is carried out continuously for several hours at a space velocity (GHSV) of 12000mL / (g·h). The gas effluent from the reactor is analyzed online using a gas chromatograph (GC-7920) equipped with a thermal conductivity detector (TCD) and a flame ionization detector (FID).
[0027] The beneficial effects of this invention are as follows:
[0028] This invention prepares an In₂O₃ catalyst with a MOF epitaxial growth structure. Using a pre-synthesized metallic MOF as a substrate, indium sources and ligands are introduced into the reaction system. By controlling the reaction conditions, the indium-based metal-organic framework is directionally coordinated and grown on the surface and interface of the substrate MOF, forming a heterostructure with a well-defined crystal structure. This eliminates the need for subsequent additional loading steps, simplifying the preparation process and improving loading stability. Based on a rational preparation process of "epitaxy growth" and "calcination," this invention enhances the oxygen vacancy activity of the metal phase without causing the organic ligands to be consumed and leading to MOF structure collapse. The heterometallic MOF epitaxial growth structure retains the inherent characteristics of MOFs—high specific surface area and porous structure—while ensuring that the heterometallic component and the indium-based metal-organic framework are not simply physically mixed, but rather form a more advanced doping with greater interfacial activity and spatial interlocking relationships. From a catalytic effect perspective, the In₂O₃ catalyst with a MOF epitaxial growth structure prepared by this invention achieves a synergistic coupling of loading and doping effects. Detailed Implementation
[0029] The present invention will now be described in further detail so that those skilled in the art can implement it based on the description.
[0030] Example 1: Zn MOF@In MOF In2O3 catalyst with epitaxial growth structure
[0031] First, 1 mmol of Zn(NO3)2·6H2O was dissolved in 15 mL of DMF, and then 15 mL of DMF solution containing 0.166 g BDC was added. The mixture was stirred for 30 min to ensure thorough mixing. The solution was then transferred to a 100 mL PTFE reactor liner and reacted in an oven at 120 °C for 24 h. The precipitate was collected by centrifugation, washed several times with DMF and ethanol, and dried to obtain Zn MOF. Subsequently, 1.492 g of In(NO3)3·4H2O, 0.58 g of PVP, and 0.54 g of Zn MOF were dispersed in 30 mL of DMF solution, and 30 mL of DMF solution containing 0.664 g BDC was added. After thorough stirring, the resulting suspension was transferred to a 100 mL PTFE reactor liner and reacted in an oven at 120 °C for 12 h. The precipitate was collected by centrifugation, washed several times with DMF and ethanol, and dried to obtain Zn MOF@In MOF. Zn MOF@In MOF was calcined in a tube furnace at 500℃ under an inert Ar atmosphere for 2 hours to obtain an In2O3 catalyst with an epitaxial growth structure, denoted as m-ZnO / InO.
[0032] Example 2: Ga MOF@In MOF In2O3 catalyst with epitaxial growth structure
[0033] First, 1 mmol of Ga(NO3)3·4H2O was dissolved in 15 mL of LDMF to prepare Ga MOF; then 1.492 g of In(NO3)3·4H2O, 0.58 g of PVP and 0.52 g of GaMOF were added, and the other steps were the same as in Example 1.
[0034] Example 3: Cu MOF@In MOF In2O3 catalyst with epitaxial growth structure
[0035] First, 1 mmol of Cu(NO3)2·3H2O was dissolved in 15 mL of DMF, and 0.216 g of trimesic acid (BTC) was added to prepare Cu MOF; then 1.492 g of In(NO3)3·4H2O, 0.58 g of PVP and 0.51 g of Cu MOF were added, and the other steps were the same as in Example 1.
[0036] Example 4: In2O3 catalyst with epitaxial growth structure of Mg MOF@In MOF
[0037] First, 1 mmol of Mg(NO3)3·6H2O was dissolved in 15 mL of DMF to prepare Mg MOF; then 1.492 g of In(NO3)3·4H2O, 0.58 g of PVP and 1.28 g of Mg MOF were added, and the other steps were the same as in Example 1.
[0038] Comparative Example 1: Preparation of In2O3 from Urea via Hydrothermal Method
[0039] 0.5595 g of In(NO3)3·4H2O and 1 g of urea were dissolved in 90 mL of water. After stirring for 30 min, the mixture was transferred to a 150 mL PTFE-lined stainless steel autoclave and kept in an oven at 120 °C for 24 h. The white precipitate was collected by centrifugation, washed three times with water, and dried overnight in an oven at 80 °C. Finally, it was calcined in a muffle furnace at 500 °C for 2 h to obtain pure phase In2O3, denoted as h-InO.
[0040] Comparative Example 2: Preparation of In2O3 by MOF calcination derivatization
[0041] Dissolve 0.373 g In(NO3)3·4H2O in 30 mL of DMF solution, add 30 mL of DMF solution containing 0.166 g BDC, stir thoroughly, transfer the resulting mixed solution to a hydrothermal reactor and react at 120 °C for 12 h, collect the precipitate by centrifugation, wash several times with DMF and ethanol, dry overnight, and then calcine the product in a tube furnace at 500 °C for 2 h under an Ar atmosphere to obtain In2O3 derived from MOF, denoted as m-InO.
[0042] Comparative Example 3: Preparation of ZnO / In2O3 by coprecipitation method
[0043] 1.6919 g of Zn(NO3)2·6H2O and 3.73 g of In(NO3)3·4H2O were dissolved in 300 mL of water, heated to 80 °C, and 1 mol / L Na2CO3 solution was added dropwise to the mixed solution until the pH reached 9. After stirring for 4 h, the mixture was allowed to stand at room temperature for 24 h, the precipitate was collected by centrifugation, washed with deionized water until neutral, and the product was dried overnight in an oven at 80 °C. Finally, it was calcined in a muffle furnace at 500 °C for 2 h to obtain the coprecipitate ZnO / In2O3, denoted as c-ZnO / InO.
[0044] Comparative Example 4: Preparation of ZnO / In2O3 by Deposition and Precipitation Method
[0045] 0.25 g of commercial ZnO and 2.164 g of In(NO3)3·4H2O were added to a 60 mL mixture of ethanol and water (volume ratio 3:1). The mixture was heated to 80 °C in a water bath and stirred thoroughly. 18 mL of ammonia water was added dropwise to the suspension. After stirring for 3 h, the precipitate was collected by centrifugation and washed with deionized water until neutral. The product was dried overnight in an oven at 80 °C and finally calcined in a muffle furnace at 500 °C for 2 h to obtain the catalyst prepared by the precipitation method in Examples 1 and Comparative Examples 1-4. The specific steps are as follows: 0.15 g of the calcined catalyst and 0.15 g of quartz sand were taken. The reactor was placed in a quartz reaction tube in a fixed-bed reactor, and N2 was introduced into it. Activation was carried out for 1 hour at atmospheric pressure and 200°C. The temperature was then increased to the reaction temperature of 260°C, and the reactor was irradiated with a 300W xenon lamp. A mixed gas of CO2, H2, and N2 (feed ratio of 1:3:1) was introduced and pressurized to 3MPa. The reactor was continuously reacted for several hours at a space velocity (GHSV) of 12000 mL / (g·h). The gas emanating from the reactor was analyzed online using a gas chromatograph (GC-7920) equipped with a thermal conductivity detector (TCD) and a flame ionization detector (FID).
[0046] Figure 1 , Figure 2 , Figure 3 , Figure 6The catalysts prepared in Examples 1 and Comparative Examples 1-4 demonstrate superior performance in the catalytic reduction of CO2 via hydrogenation. The m-ZnO / InO prepared in Example 1 exhibits significantly higher CO2 conversion (8.58%) and methanol selectivity (90.5%). By adjusting the initial molar ratio of Zn and In sources and optimizing parameters for different preparation methods, the metal oxide content of catalysts prepared by different methods after calcination is precisely normalized, effectively eliminating interference from differences in component content on catalytic performance evaluation. This shows that the In2O3 catalyst with an epitaxial growth structure prepared in this invention achieves several-fold improvements in catalytic efficiency compared to conventional MOF-supported In2O3 and In2O3 hybrid materials, particularly in terms of catalytic product space-time yield. Attached Figure Description
[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0048] Figure 1 The performance of In2O3 catalysts prepared by different methods in catalyzing CO2 reduction—CO2 conversion rate;
[0049] Figure 2 The performance of In2O3 catalysts prepared by different methods in catalyzing CO2 reduction—methanol selectivity;
[0050] Figure 3 Performance of In2O3 catalysts prepared by different methods for CO2 reduction – space-time yield of methanol.
[0051] Figure 4 The FTIR characterization spectrum of the In2O3 catalyst with epitaxial growth structure obtained by the present invention is shown below (Zn MOF@In MOF: In2O3 catalyst with epitaxial growth structure; Zn MOF: zinc-based metal-organic framework precursor A; In MOF: In2O3 prepared by MOF calcination derivatization).
[0052] Figure 5 The N2 adsorption-desorption isotherm and specific surface area radar diagram of the In2O3 catalyst with epitaxial growth structure obtained by the present invention, Zn MOF@In MOF.
[0053] Figure 6To investigate the space-time yield of methanol over 24 hours in the CO2 hydrogenation reaction using the In2O3 catalyst with epitaxial growth structure obtained by Zn MOF@In MOF obtained in this invention (ZnO / In2O3: In2O3 catalyst with epitaxial growth structure of Zn MOF@In MOF; h-In2O3: In2O3 prepared by hydrothermal method of urea).
Claims
1. An In2O3 catalyst with an epitaxially grown structure, comprising a metal-organic framework precursor A and an indium-based metal-organic framework B, wherein the indium-based metal-organic framework B is epitaxially grown on the metal-organic framework precursor A, and the catalyst is obtained by calcination. The catalyst includes the following steps: Step 1: Dissolve a certain mass of soluble metal salt and terephthalic acid BDC in N,N-dimethylformamide DMF solution. Transfer the mixed solution to a polytetrafluoroethylene reactor liner and react for several hours. Centrifuge to collect the precipitate, wash with DMF and ethanol several times, and dry to obtain metal-organic framework precursor A. Step 2: Take a certain mass of soluble indium salt, polyvinylpyrrolidone (PVP), and the metal-organic framework precursor A prepared in Step 1, disperse them in DMF solution, add a certain mass of DMF solution containing BDC, stir thoroughly, transfer the resulting suspension to a hydrothermal reactor and react for several hours, centrifuge to collect the precipitate, wash with DMF and ethanol several times, and dry to obtain indium-based metal-organic framework B epitaxially grown on metal-organic framework precursor A; Step 3: The In-based metal-organic framework B epitaxially grown on metal-organic framework A is calcined in a tube furnace.
2. The In2O3 catalyst with an epitaxial growth structure according to claim 1, characterized in that... The metal center of metal-organic framework precursor A is a heterometal with indium.
3. The In2O3 catalyst with an epitaxial growth structure according to claim 1, characterized in that... The metal-organic framework A has a metal center of Zn, Ga, Cu, or Mg.
4. The In2O3 catalyst with an epitaxial growth structure according to claim 1, characterized in that... The soluble metal salt and soluble indium salt are Zn(NO3)2·6H2O, Ga(NO3)3·4H2O, Cu(NO3)2·3H2O, Mg(NO3)2·6H2O, and In(NO3)3·4H2O.
5. The In2O3 catalyst with an epitaxial growth structure according to claim 1, characterized in that... The relative molecular mass of the polyvinylpyrrolidone (PVP) is 58,000.
6. The In2O3 catalyst with an epitaxial growth structure according to claim 1, characterized in that... The synthesis temperature range of the metal-organic framework A and the In2O3 catalyst with epitaxial growth structure is 100-140℃, and the reaction time is 6-48h.
7. The In2O3 catalyst with an epitaxial growth structure according to claim 1, characterized in that... The In2O3 catalyst with epitaxial growth structure has a metal mass fraction of 5-50% and an added metal-organic framework precursor A mass of 0.1-2.5g.
8. The In2O3 catalyst with an epitaxial growth structure according to claim 1, characterized in that... The roasting temperature of the roasting treatment is 400-600℃, the roasting time is 1-6h, and the inert atmosphere gas is N2 or Ar.
9. The In2O3 catalyst with an epitaxial growth structure according to claims 1-8, characterized in that... The In2O3 catalyst with an epitaxial growth structure, or the In2O3 catalyst with an epitaxial growth structure prepared by the preparation method of the In2O3 catalyst with an epitaxial growth structure, is used in CO2 heating catalytic reduction reaction, CO2 photocatalytic reduction reaction or CO2 electrocatalytic reduction reaction.
10. The In2O3 catalyst with an epitaxial growth structure according to claim 9 is used in the reaction of CO2 hydrogenation reduction to prepare methanol or CO, characterized in that, 0.15g of catalyst and 0.15g of quartz sand were placed in the quartz reaction tube of a fixed-bed reactor, and N2 was introduced into it. Activation was carried out for 1 hour at atmospheric pressure and 200℃. The temperature was then increased to the reaction temperature of 260℃, and irradiated with a 300W xenon lamp. A mixed gas of CO2, H2, and N2 (feed ratio of 1:3:1) was introduced and pressurized to 3MPa. The reaction was carried out continuously for several hours at a space velocity GHSV = 12000mL / (g·h). The gas outlet gas of the reactor was analyzed online using a gas chromatograph (GC-7920) equipped with a thermal conductivity detector (TCD) and a flame ionization detector (FID).