A supported catalyst Pt / PC-In2O3, its preparation method, and its application in methanol aqueous reforming for hydrogen production.

Abstract

The application provides a supported catalyst Pt / PC-In2O3, a preparation method and application of the catalyst in hydrogen production by methanol aqueous-phase reforming, and solves the technical problems of complex preparation process and CO selectivity of the hydrogen production catalyst by methanol aqueous-phase reforming. The application first prepares a cubic In(OH)3 precursor with uniform morphology through a simple one-step hydrothermal method, controls the reaction temperature and reaction time in a strong alkali environment through the hydrothermal method, then performs calcination and oxidation in an air atmosphere to convert the In(OH)3 into stable porous cubic structure In2O3, and finally prepares the supported catalyst Pt / PC-In2O3 through a traditional impregnation method.

Description

Technical Field

[0001] This invention belongs to the field of thermocatalysis technology, specifically relating to a supported catalyst Pt / PC-In2O3, its preparation method, and its application in methanol aqueous reforming for hydrogen production. Background Technology

[0002] In heterogeneous catalytic reactions, the rational design and synthesis of catalysts often play a crucial role in catalytic performance. However, most current catalyst preparation processes are complex and struggle to achieve the application value of "high selectivity".

[0003] Currently, methanol aqueous reforming for hydrogen production can release hydrogen in situ, avoiding complex and cumbersome experimental equipment, and the reaction temperature is relatively low. However, the catalysts used not only have complex preparation processes, but also struggle to achieve both high activity and high selectivity for hydrogen. For example, although Pt / α-MoC catalysts have achieved high-activity methanol aqueous reforming for hydrogen production at low temperatures (<200℃), they have failed to solve the problem of CO selectivity.

[0004] In view of this, the research team of this invention believes that it is necessary to design a catalyst for methanol aqueous reforming hydrogen production that has a simple preparation process and can take into account both high activity and high selectivity for hydrogen, so as to solve the problem of CO selectivity. Summary of the Invention

[0005] The purpose of this invention is to solve the technical problems of complex preparation process and CO selectivity of current methanol aqueous reforming hydrogen production catalysts, and to provide a supported catalyst Pt / PC-In2O3, its preparation method and its application in methanol aqueous reforming hydrogen production.

[0006] The concept of this invention:

[0007] To address the existing problems with current methanol aqueous reforming hydrogen production catalysts, our research team considers the following requirements for catalyst design: 1) Effective activation of small molecule H2O, converting it into *H and *OH intermediates, providing a basis for further WGS (water-gas shift reaction); 2) Avoiding the generation of byproduct CO, which would reduce hydrogen purity and limit its application in proton exchange membrane fuel cells. Therefore, considering the design requirements of methanol aqueous reforming hydrogen production catalysts and the current bottlenecks, our research team proposes a dual-site activation approach. In2O3 has unique and abundant oxygen vacancies on its surface, effectively activating small molecules such as H2, CO2, and CH4. Our research also found that In2O3 has excellent activation capabilities for H2O. Furthermore, methanol is easily activated by Pt. Therefore, our research team plans to prepare a supported catalyst, Pt / PC-In2O3, using the noble metal Pt and the support In2O3 to simultaneously activate the substrate, achieving the application of a bifunctional catalyst. Currently, the morphology of most In2O3 is difficult to control, which hinders the direct utilization of existing In2O3. The preparation process of regular In2O3 is cumbersome, or requires the addition of substances such as oleylamine, leading to complex post-processing of samples and residual impurities, making it difficult to establish a structure-activity relationship between the catalytic activity and structure of In2O3. Although post-modification can solve the problem of In2O3 deactivation, it wastes raw materials, which is economically disadvantageous. Therefore, our research team optimized the preparation process of In2O3, first preparing porous cubic In2O3 (PC-In2O3), and then loading Pt in single-atom form within its pores to form a supported catalyst, Pt / PC-In2O3, to solve the selectivity problem of CO in methanol aqueous reforming for hydrogen production.

[0008] Based on the above inventive concept, and to achieve the above objectives, the technical solution provided by this invention is as follows:

[0009] A method for preparing a supported catalyst Pt / PC-In2O3, characterized by the following steps:

[0010] 1) In a strong alkaline solution, add dropwise a solution prepared from In(NO3)3·5H2O (MACKLIN 99.99% metals basis) and ultrapure water (other solutions containing In can also be added). 3+ The present invention uses In(NO3)3·5H2O as the preferred solution because of its good solubility and the fact that NO3... - (Ions do not affect the product and are easily removed by washing). An In(OH)3 precursor with a regular cubic morphology was prepared by a hydrothermal method. -The molar concentration in the reaction solution is 6M to 9M; in this invention, In is first precipitated by adding a strong base with a concentration of 6M to 9M. 3+ It is easy to form a uniform morphology, and through hydrothermal reaction, the crystallinity is improved and the growth of some crystal faces is inhibited, so as to prepare an In(OH)3 precursor with a uniform morphology.

[0011] 2) The In(OH)3 precursor obtained in step 1) was calcined in air at 250℃-350℃ for 2-4 hours (after 2 hours of calcination, the morphology of the product tends to be stable), and then naturally cooled to obtain a porous cubic indium oxide PC-In2O3 with uniform morphology.

[0012] 3) Platinum is loaded onto the porous cubic indium oxide support obtained in step 2) by conventional impregnation and reduced in an argon / hydrogen mixture to obtain the supported catalyst Pt / PC-In2O3 (PC represents porous cubic structure). The loading of Pt is no more than 0.2 wt% (i.e., the mass ratio of Pt to PC-In2O3, which can be determined by ICP-OES / MS test results). Only when the loading of Pt is within this range can it exist in the form of single atoms and exert the expected activation effect.

[0013] Furthermore, in step 1), NaOH is chosen as the strong base, but other strong bases, such as KOH, can also be used. The specific steps are as follows:

[0014] NaOH was slowly added to a polytetrafluoroethylene liner containing ultrapure water and stirred. After the NaOH solution cooled, a solution prepared from In(NO3)3·5H2O and ultrapure water was slowly added dropwise. After the addition was complete, the mixture was stirred at room temperature and placed in a reaction vessel. The reaction was carried out at 100℃~120℃ for 12~24h. After the reaction was completed, the mixture was washed several times with water and alcohol alternately, and then dried at 60℃~80℃ for 8~12h to obtain the In(OH)3 precursor.

[0015] Furthermore, in step 1), the concentration of NaOH (Alfa Aesar 98%) in the reaction solution is 6M, at which a precursor with stable and uniform morphology can be obtained.

[0016] Further, in step 2), the In(OH)3 precursor obtained in step 1) is placed in a muffle furnace and calcined at 250°C for 2 hours in air at a heating rate of 5°C / min, followed by natural cooling to obtain porous cubic indium oxide. During the research process, the team discovered that the transformation temperature of In(OH)3 is around 200°C, and that temperature affects the structure and morphology of the pores. 250°C is the temperature at which the morphology is best preserved; therefore, in step 2), 250°C is preferred as the calcination temperature.

[0017] Further, step 3) specifically involves dispersing the porous cubic In2O3 obtained in step 2) in ethanol, adding an aqueous solution of chloroplatinic acid (H2PtCl6) dropwise, stirring at room temperature for 2 hours, evaporating to dryness, and then calcining at 200°C at a rate of 5°C / min in a 10% H2 / Ar atmosphere for 2 hours to obtain the supported catalyst Pt / PC-In2O3.

[0018] The present invention also provides a supported catalyst Pt / PC-In2O3 prepared by the above preparation method, wherein the Pt loading is not higher than 0.2 wt%, and its application as a catalyst in methanol aqueous reforming for hydrogen production. This catalyst can effectively solve the problems of complex preparation process and difficulty in achieving high selectivity and high activity of existing catalysts. It can avoid the generation of carbon monoxide under high temperature reaction conditions and realize the preparation of high-purity hydrogen.

[0019] Based on the above applications, the present invention further provides a method for producing hydrogen from methanol via aqueous reforming, characterized in that the operation is as follows:

[0020] The Pt / PC-In2O3 prepared by the above method was uniformly dispersed in a mixed solution of water and methanol, and then transferred to a high-pressure reactor and purged with nitrogen (nitrogen serves two purposes: as a protective gas and to facilitate hydrogen testing after the reaction; the specific pressure is not required, 2 MPa can be used) for reaction at a temperature of 120-180℃. After the reaction is complete, high-purity hydrogen is obtained, and the CO content in the product is <5 ppm, which is below the FID detection limit. Specifically, the Pt / PC-In2O3 catalyst was ultrasonically dispersed in a mixed solution of water and methanol (where the volume ratio of water to methanol is 9:20; the mass-volume ratio of Pt / PC-In2O3 catalyst to the water-methanol mixture is 25:29, mg / mL). The dispersed solution was then transferred to an automated magnetically stirred high-pressure reactor (IKA), rinsed three times with nitrogen, and finally the reaction pressure was set to 2 MPa, the reaction time to 1 h, and the reaction temperature to 180℃. After the reaction is complete, immediately immerse the container in an ice-water bath. Once the temperature drops below 20°C, collect the gas after the reaction using a gas collecting bag. Analyze the gas components using gas chromatography-TCD and FID, and calculate the amounts of H2 and CO.

[0021] The principle of this invention:

[0022] This invention first prepares a uniform cubic In(OH)3 precursor using a simple one-step hydrothermal method under a strongly alkaline environment, controlling the reaction temperature and time. Then, it undergoes calcination oxidation in air to convert In(OH)3 into a stable porous cubic In2O3 structure. Finally, a supported catalyst, Pt / PC-In2O3, is prepared using a conventional impregnation method. The overall design concept involves designing dual-site activation of methanol and water at different locations. To obtain regular cubic structures, this invention chooses a strong alkaline solution such as sodium hydroxide, which is more conducive to the preparation of well-crystallized indium hydroxide; this condition is essential for the preparation of regular cubic structures. Furthermore, different calcination temperatures affect the degree of conversion of In(OH)3 to In2O3, the number of surface oxygen vacancies, and the maintenance of the microstructure. This invention achieves the preparation of a porous support with a large specific surface area by controlling the molar concentration of the strong base in the reaction solution (6M–9M) and the calcination temperature (250℃–350℃). Transmission electron microscopy and nitrogen adsorption-desorption tests revealed that calcination at 250℃ best maintains the optimal performance, preserving the homogeneous cubic structure and maximizing the specific surface area. Finally, performance testing showed that this Pt / PC-In₂O₃ catalyst exhibits excellent catalytic activity in the methanol aqueous reforming hydrogen production reaction.

[0023] The advantages of this invention are:

[0024] 1. This invention provides a strategy for preparing a catalyst that can simultaneously activate methanol and water and effectively avoid the generation of carbon monoxide in methanol aqueous reforming for hydrogen production. Using porous cubic In2O3 as a support, single-atom Pt is loaded through conventional impregnation to generate a uniformly sized porous cubic catalyst Pt / PC-In2O3. The entire operation is simple, requires fewer raw materials, and is highly economical, effectively solving the selectivity problem of carbon monoxide in methanol aqueous reforming for hydrogen production.

[0025] 2. This invention designs a Pt / PC-In2O3 catalyst by utilizing the design concept of dual active sites, specifically Pt activating CH3OH and In2O3 activating H2O. The process is simple, and the OH group is controlled... - By adjusting the molar concentration in the reaction solution, a precursor In(OH)3 with a regular morphology was prepared. Simultaneously, by controlling the calcination temperature, In2O3 with a high number of oxygen vacancies was prepared. During the reaction, the oxygen vacancies were maintained and not deactivated. Finally, the Pt single atoms of CH3OH were effectively activated, achieving the effect of bifunctional catalysis. No additional substances or post-treatment were required during the preparation of In2O3. The In2O3 has a regular cubic structure and a porous structure.

[0026] 3. The Pt / PC-In2O3 catalyst prepared by this invention exhibits a high H2 generation rate and a low CO concentration (<5ppm) within a reaction temperature range of 120-180℃. This means that while accelerating the hydrogen production rate, it also avoids the generation of the byproduct CO, effectively solving the problem of hydrogen purity and avoiding the additional steps of subsequent gas purification. It can be directly used in proton exchange membrane fuel cells, further solving the bottleneck problem of methanol aqueous reforming hydrogen production in the field of proton exchange membrane fuel cells. Attached Figure Description

[0027] Figure 1 The following are images showing the preparation process and morphology of PC-In2O3 in Example 1: a) Flowchart of the experimental preparation; b) Transmission electron microscope (TEM) image; cd) High-resolution TEM image; ef) Interplanar spacing diagram; g) High-angle annular dark field and corresponding elemental distribution diagram.

[0028] Figure 2 The morphology and elemental distribution of the precursor In(OH)3 during the preparation of PC-In2O3 in Example 1 are shown in the following diagrams: a) Transmission electron microscopy (TEM) image; b) High-resolution TEM image; c) Interplanar spacing diagram; df) High-angle annular dark field and corresponding elemental distribution diagram.

[0029] Figure 3 Morphological characterization of In2O3-350: a) Transmission electron microscopy (TEM) image; bc) High-resolution TEM image; df) High-angle annular dark field and corresponding elemental distribution map;

[0030] Figure 4 Morphological characterization of In2O3-450: a) Transmission electron microscopy (TEM) image; bc) High-resolution TEM image; df) High-angle annular dark field and corresponding elemental distribution map;

[0031] Figure 5 Morphological characterization of In2O3-1∶9; a) Transmission electron microscopy (TEM) image; b) High-resolution transmission electron microscopy (HRTEM) image;

[0032] Figure 6 Morphological characterization of In2O3-1∶3; a) Transmission electron microscopy (TEM) image; b) High-resolution transmission electron microscopy (HRTEM) image;

[0033] Figure 7 Morphological characterization of In2O3-NH4OH: a) Transmission electron microscopy (TEM) image; b) High-resolution transmission electron microscopy (HRTEM) image;

[0034] Figure 8 Morphological characterization of In2O3-Unheated: a) Transmission electron microscopy (TEM) image; b) High-resolution transmission electron microscopy (HRTEM) image;

[0035] Figure 9The morphology of NP-In2O3 is shown in the following diagrams: a) Transmission electron microscopy (TEM) image; b) High-resolution TEM image; c) Interplanar spacing diagram; df) High-angle annular dark field and corresponding elemental distribution diagram.

[0036] Figure 10 Structural characterization of different indium oxides; a) Different indium oxides O 1s a) XPS spectrum; b) nitrogen adsorption-desorption curve; c) electron paramagnetic resonance spectrum;

[0037] Figure 11 Morphology, elemental distribution, and synchrotron radiation absorption spectrum of Pt / PC-In2O3 catalyst;

[0038] Figure 12 The image shows the morphology of the Pt / NP-In2O3 catalyst, the exposed Pt crystal faces, and the intensity distribution of interplanar spacing.

[0039] Figure 13 The following graphs show the catalytic performance of Pt / PC-In2O3 catalyst for hydrogen production in methanol aqueous reforming: a) Comparison of hydrogen production rates of different catalysts; b) Comparison of intrinsic catalytic activities of different catalysts; c) Selectivity of carbon monoxide for different catalysts; d) Activation energy of different catalysts; e) Cyclic stability and carbon monoxide selectivity of Pt / PC-In2O3 catalyst. Detailed Implementation

[0040] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0041] This invention discloses a supported catalyst Pt / PC-In2O3, its preparation method, and its application in methanol aqueous reforming for hydrogen production. The technical solution of this invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments.

[0042] In the initial stage of preparing the supported catalyst Pt-In2O3, the preparation of the In2O3 support was first investigated as follows:

[0043] Example 1

[0044] like Figure 1 As shown in a, the preparation of porous cubic indium oxide includes the following steps:

[0045] (1) Preparation of In(OH)3 precursor

[0046] First, add 70 mL of ultrapure water to a 100 mL polytetrafluoroethylene inner liner and place a magnetic stirrer inside. Then, slowly add 19.2 g of sodium hydroxide to the 70 mL of ultrapure water and stir for 30 minutes. After the NaOH solution cools, slowly add the prepared solution containing In. 3+The solution (prepared by ultrasonically dispersing 1.203 g In(NO3)3·5H2O in 10 mL of ultrapure water) was used. During the dropwise addition, the solution gradually turned milky white. After the addition was complete, the mixture was stirred at room temperature for 30 minutes, then transferred to a reaction vessel and reacted at 100°C for 24 hours in a forced-air drying oven. After the reaction was completed, the mixture was washed three times alternately with water and alcohol, and then dried at 60°C for 8 hours in a forced-air drying oven to obtain the In(OH)3 precursor. In this example, the molar concentration of sodium hydroxide in the reaction solution was controlled at 6 M.

[0047] (2) Preparation of different In2O3-based catalysts

[0048] The precursor In(OH)3 obtained in step 1) was placed in a muffle furnace and calcined at 250°C for 2 hours in air atmosphere at a heating rate of 5°C / min. After natural cooling, the sample PC-In2O3 was obtained and named In2O3-250.

[0049] Example 2

[0050] The difference from Example 1 is that in step 2) of this example, calcination at 300°C for 2 hours is used to obtain sample In2O3-300.

[0051] Example 3

[0052] The difference from Example 1 is that in step 2) of this example, calcination at 350°C for 2 hours is used to obtain sample In2O3-350.

[0053] Example 4

[0054] The difference from Example 1 is that the amount of sodium hydroxide added in this example is increased, and the molar concentration of sodium hydroxide in the reaction solution is controlled at 9M to obtain sample In2O3-1∶9.

[0055] Comparative Example 1

[0056] The difference from Example 1 is that in step 2) of this example, calcination at 450°C for 2 hours is used to obtain sample In2O3-450.

[0057] Comparative Example 2

[0058] The difference from Example 1 is that the amount of sodium hydroxide added is reduced in this example, and the molar concentration of sodium hydroxide in the reaction solution is controlled at 3M to obtain sample In2O3-1∶3.

[0059] Comparative Example 3

[0060] The difference from Example 1 is that in step 1) of this example, sodium hydroxide is replaced with ammonia water, and the mass of ammonia water is 0.48g, resulting in sample In2O3-NH4OH.

[0061] Comparative Example 4

[0062] The difference from Example 1 is that in step 1) of this example, the hydrothermal method was not used to prepare the In(OH)3 precursor; only the prepared In-containing precursor was used. 3+ The solution was slowly added dropwise to a sodium hydroxide solution, stirred, and allowed to stand to generate the In(OH)3 precursor. The resulting sample was In2O3-Unheated.

[0063] Comparative Example 5

[0064] In this embodiment, an NP-In2O3 catalyst was prepared by the following method:

[0065] Weigh 1g In(NO3)3·5H2O and place it in a 50mL dry pot. Transfer the dry pot to a muffle furnace, set the heating rate to 5℃ / min, and calcine at 250℃ for 2 hours. After the reaction is complete, allow it to cool naturally to room temperature to obtain NP-In2O3.

[0066] To verify the effectiveness, the present invention also conducted the following experimental examples:

[0067] I. Morphological and structural characterization of the precursor In(OH)3 prepared in Example 1, and indium oxide obtained under different conditions in Examples 1, 3, 4, and Comparative Examples 1-5:

[0068] Figure 2 Here are the morphology and elemental distribution diagrams of the precursor In(OH)3: Figure 2 As shown in a, In(OH)3 has a uniform cubic structure; Figure 2 b and c show that their main exposed crystal plane is (220) with a crystal plane spacing of 0.284 nm; Figure 1 The df data shows that In (green) and O (red) elements are evenly distributed throughout the material.

[0069] Figure 1 The morphology and elemental distribution of In2O3-250 are shown in the following diagram: Figure 1 Figure b shows that under a calcination temperature of 250℃, In₂O₃ forms uniformly sized blocky cubes; from Figure 1 As can be clearly seen from point c, the cube has a porous structure; Figure 1 The d-plane shows a spacing of 0.293 nm, which belongs to the (222) plane of In2O3; Figure 1 The ef is a crystal plane spacing intensity distribution diagram, which can accurately and scientifically show the crystal plane spacing; Figure 1 The g indicates that In (green) and O (yellow) elements are evenly distributed throughout the material.

[0070] Figure 3The morphology and elemental distribution spectrum of In2O3-350 are shown below: Figure 3 As shown in Figure a, In₂O₃-350 has a porous cubic structure, and compared to In₂O₃-250, the bulk material shows accumulation upon increasing the temperature; for example... Figure 3 b shows that the edges of the blocky body overlap, and the morphology begins to change. Figure 3 c shows that its interplanar spacing is 0.296 nm, which is consistent with In2O3-250 and belongs to the (222) crystal plane of In2O3; Figure 3 The df data shows that In (green) and O (yellow) elements are evenly distributed throughout the material.

[0071] Figure 4 The morphology and elemental distribution spectrum of In2O3-450 are shown below: Figure 4 As shown in Figure a, In₂O₃-450 exhibits an irregular, blocky structure. Compared to In₂O₃-250, the morphology of indium oxide changes significantly when the calcination temperature is increased to 450℃; for example... Figure 4 As shown in b, the porous structure is still maintained, but the number of pores is significantly reduced compared to In2O3-250 and In2O3-350; Figure 4 c shows that its interplanar spacing is 0.296 nm, which is consistent with In2O3-250 and belongs to the (222) crystal plane of In2O3; Figure 4 The df data shows that In (green) and O (yellow) elements are evenly distributed throughout the material.

[0072] Figure 5 Morphological characterization diagram of In2O3-1∶9: as shown Figure 5 As shown in a, In2O3-1∶9, like In2O3-250 in Example 1, is a uniformly sized blocky cube. Figure 5 As can be clearly seen from b, the cubic block has a porous structure and undoubtedly has the same catalytic performance as In2O3-250 in Example 1.

[0073] Figure 6 Morphological characterization of In₂O₃⁻ 1:3: From Figure 6 As shown in a, In₂O₃⁻ 1:3 exhibits a random, blocky structure. Compared to In₂O₃⁻ 250, when the molar concentration of sodium hydroxide in the reaction solution is controlled at 3M, the morphology of indium oxide changes significantly, demonstrating the crucial importance of the molar concentration of hydroxide ions in the reaction solution. Figure 6 As shown in b, it retains a partially porous structure, but the number of pores is significantly reduced compared to In2O3-250, In2O3-350, and In2O3-1∶9.

[0074] Figure 7Morphological characterization diagram of In2O3-NH4OH: From Figure 7 As shown in a, In₂O₃-NH₄OH has an irregular blocky structure, indicating that uniformly sized blocky cubes cannot be prepared in a weak base; for example... Figure 7 As shown in b, the structure retains many pores, but the number of pores is significantly reduced compared to the sample prepared under strong alkaline conditions.

[0075] Figure 8 Morphological characterization of In2O3-Unheated: From Figure 8 As shown in a, In₂O₃-Unheated exhibits mostly irregular blocky structures, indicating that the hydrothermal preparation process in step 1) is also a prerequisite for obtaining uniformly sized blocky cubic structures; for example... Figure 8 b shows that it maintains a porous structure, with a significantly reduced number of pores compared to the sample prepared under strong alkaline conditions.

[0076] Figure 9 The morphology characterization diagram of NP-In2O3 is shown below; Figure 9 Figures a and b show that NP-In2O3 has an irregular blocky structure and no pores; Figure 9 c shows that its interplanar spacing is 0.293 nm, which belongs to the (222) crystal plane of In2O3; Figure 9 The df data shows that In (green) and O (yellow) elements are evenly distributed throughout the material.

[0077] 2. Structural characterization of indium oxide obtained at different calcination temperatures and NP-In2O3 prepared in Comparative Example 3.

[0078] Figure 10 For structural characterization and oxygen vacancy characterization: such as Figure 10 The a-value shows that by analyzing each indium oxide O 1s Orbit fitting revealed that In₂O₃-250 has 36.45% oxygen vacancies, significantly higher than other indium oxides; for example... Figure 10 Figure b shows that In₂O₃-250 has a large specific surface area of ​​56.11 g / m². 2 It also has a rich mesoporous structure; Figure 10 The c-value represents further measurement of oxygen vacancies using electron paramagnetic resonance, consistent with XPS results, indicating that In2O3-250 has a high oxygen vacancy rate.

[0079] Therefore, subsequent supported catalysts Pt-In2O3 were all studied based on In2O3-250.

[0080] Example 4

[0081] A method for preparing a supported catalyst Pt / PC-In2O3 includes the following steps:

[0082] (1) The In(OH)3 precursor was prepared using the same method as in Example 1.

[0083] (2) Porous cubic In2O3 (i.e., In2O3-250) was prepared using the same method as in Example 1.

[0084] (3) Preparation of supported catalyst Pt / PC-In2O3 (Pt loading is 0.2 wt%):

[0085] Weigh 200 mg of the porous cubic In2O3 prepared in step 2), place it in a 50 mL dry pot, add 30 mL of ethanol and ultrasonically disperse it, add 80 μL (Pt wt%: 5 mg / mL) of chloroplatinic acid aqueous solution dropwise to the solution, stir at room temperature for 2 hours, heat to 90 °C to completely evaporate, then heat to 200 °C at a rate of 5 °C / min in a 10% H2 / Ar mixed gas and calcine for 2 hours to obtain the supported catalyst Pt / PC-In2O3.

[0086] Comparative Example 6

[0087] The method for preparing Pt / In(OH)3 catalyst is as follows:

[0088] In(OH)3 was prepared using the method described in step 1) of Example 1. 200 mg of In(OH)3 was weighed and placed in a 50 mL dry pot. 30 mL of ethanol was added and the mixture was ultrasonically dispersed. 80 μL of a chloroplatinic acid aqueous solution (Pt wt%: 5 mg / mL) was added dropwise to the solution. After stirring at room temperature for 2 hours, the mixture was heated to 90 °C and completely evaporated. Then, the mixture was calcined in a 10% H2 / Ar mixed gas at a rate of 5 °C / min to 200 °C for 2 hours to obtain the Pt / In(OH)3 catalyst.

[0089] Comparative Example 7

[0090] Preparation of Pt / C, Pt / TiO2, and Pt / Al2O3 catalysts:

[0091] The preparation method of the above catalyst is the same as that of the Pt / In(OH)3 catalyst in Comparative Example 6, except that the corresponding support is replaced with C, TiO2, and Al2O3, while other conditions remain unchanged.

[0092] Comparative Example 8

[0093] Preparation of Pt / NP-In2O3 catalyst

[0094] ① NP-In2O3 was prepared using the method described in Comparative Example 3;

[0095] ②The Pt / NP-In2O3 catalyst is also impregnated in the same way as the Pt / In(OH)3 catalyst in Comparative Example 6, except that In(OH)3 is replaced with NP-In2O3, and other conditions remain unchanged.

[0096] To verify the catalytic performance of the supported catalyst Pt / PC-In2O3 of this invention, the following experimental examples were also conducted:

[0097] I. The morphology and structure of Pt / PC-In2O3 prepared in Example 4 and Pt / NP-In2O3 prepared in Comparative Example 8 were characterized. Specific results are shown in [the table below]. Figure 11 , Figure 12 .

[0098] Figure 11 Morphology, elemental distribution, and synchrotron radiation absorption spectrum of the Pt / PC-In2O3 catalyst: (e.g.) Figure 11 As shown in Figure a, the Pt / PC-In2O3 catalyst has a porous cubic structure, and the In (green), O (yellow), and Pt (pink) elements are uniformly distributed throughout the material. Figure 11 The high-angle annular dark field plot of b clearly shows the presence of multiple bright spots, proving that Pt was successfully loaded; Figure 11 c represents the Pt L3-edge X-ray near-edge absorption structure. The peak shape of Pt in Pt / PC-In2O3 is consistent with that of PtO2, proving that Pt exists in the +4 valence. Figure 11 The extended X-ray absorption fine structure spectrum (d) confirms that Pt mainly exists in the form of Pt-O.

[0099] Figure 12 The morphology of the Pt / NP-In2O3 catalyst, the exposed Pt crystal faces, and the intensity distribution of interplanar spacing are shown in the following diagrams: Figure 12 As shown in a, Pt / NP-In2O3 has an irregular morphology and is a non-porous bulk structure. Figure 12 Images b and c show Pt particles loaded on the surface of NP-In₂O₃. Figure 12 The d-value shows that the interplanar spacing of the Pt particles is 0.226 nm, which belongs to the (111) crystal plane.

[0100] II. The catalysts Pt / In(OH)3, Pt / C, Pt / NP-In2O3, Pt / TiO2, Pt / Al2O3 prepared in Comparative Examples 6-8 and the Pt / PC-In2O3 catalyst prepared in Example 4 were used for methanol aqueous phase reforming to produce hydrogen. The specific operations are as follows:

[0101] (1) Disperse 50 mg of catalyst evenly in 58 mL of water-alcohol mixture (40 mL CH3OH + 18 mL H2O);

[0102] (2) Transfer the mixture in (1) above to a 240mL high-pressure reactor, wash with N2 three times, and then react in N2 at 2MPa with magnetic stirring. The temperature is controlled at 180℃ for 1h.

[0103] (3) After the reaction is completed, the reaction vessel is quickly placed in an ice-water bath to cool. When the temperature reading drops below 25°C, the gas is collected in a 1L gas collecting bag and the amount of H2 is calculated by gas chromatography to detect the components.

[0104] from Figure 13 As can be seen from a, the Pt / PC-In2O3 catalyst exhibits a higher space-time yield compared to other catalysts, reaching 14.8 mmol. H2 g cat -1 h -1 The catalyst Pt / Al2O3 (4.6 mmol) H2 g cat -1 h -1 3.2 times higher; Figure 13 b represents the intrinsic activity diagram of the catalyst; the Pt / PC-In2O3 catalyst can reach 1923.1 mol / L. H2 mol Pt -1 h -1 It has significant advantages compared to other catalysts; Figure 13 The 'c' represents the CO selectivity. The CO selectivity of other catalysts is greater than 100 ppm, while no CO signal peak was detected in the Pt / PC-In2O3 catalyst (<5 ppm FID detection limit). This shows that hydrogen can be applied to proton membrane fuel cells without further purification. In other words, at a relatively high temperature of 180℃ (the higher the temperature, the higher the CO content), the Pt / NP-In2O3 catalyst prepared by this invention can produce H2 with a purity sufficient for further use. Therefore, at a low temperature of 120℃, CO release can be solved without any problem, and H2 with a purity sufficient for application can be produced. The absence of CO production during the entire reaction process also avoids catalyst poisoning. Figure 13 The value of d represents the activation energy of each catalyst. The Pt / PC-In2O3 catalyst has a relatively low activation energy (87.2 kJ mol). -1 This also explains the superior performance of the Pt / PC-In2O3 catalyst. Figure 13 The figure for e represents the cyclic stability graph. After 9 cycles, the catalytic activity remained at 1707.5 mol%. H2 mol Pt -1 h -1The intrinsic activity of Pt / PC-In2O3 demonstrates its structural stability and potential for commercialization.

[0105] In summary, the catalyst prepared by this invention can solve the technical problems of complex preparation process and CO selection in current methanol aqueous reforming hydrogen production catalysts.

[0106] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the scope of the technology disclosed in the present invention, and such modifications or substitutions should all be covered within the scope of protection of the present invention.

Claims

1. The application of a supported catalyst Pt / PC-In2O3 in methanol aqueous reforming for hydrogen production, characterized in that, The preparation method of the supported catalyst Pt / PC-In2O3 includes the following steps: 1) In a strong alkaline solution, a solution prepared by In(NO3)3·5H2O and ultrapure water is added dropwise to prepare the In(OH)3 precursor by hydrothermal method; OH - The molar concentration in the reaction solution is 6 M ~ 9 M; 2) The In(OH)3 precursor obtained in step 1) is placed in an air atmosphere and calcined at 250℃~350℃ for 2~4 hours to obtain porous cubic indium oxide; 3) Platinum is loaded onto the porous cubic indium oxide support obtained in step 2) by impregnation and reduced in an argon / hydrogen mixture to obtain the supported catalyst Pt / PC-In2O3, wherein the loading of Pt is not higher than 0.2 wt%.

2. The application according to claim 1, characterized in that: Step 1) Specifically: NaOH was slowly added to a polytetrafluoroethylene liner containing ultrapure water and stirred. After the NaOH solution cooled, a solution prepared from In(NO3)3·5H2O and ultrapure water was slowly added dropwise. After the addition was complete, the mixture was stirred at room temperature and placed in a reaction vessel. The reaction was carried out at 100℃~120℃ for 12~24 h. After the reaction was completed, the mixture was washed several times with water and alcohol alternately, and then dried at 60℃~80℃ for 8~12 h to obtain the In(OH)3 precursor.

3. The application according to claim 2, characterized in that: In step 1), the concentration of the NaOH solution is 6 M.

4. The application according to claim 3, characterized in that: In step 2), the In(OH)3 precursor obtained in step 1) is placed in a muffle furnace and calcined at 250°C for 2 hours in air at a heating rate of 5°C / min, and then naturally cooled to obtain porous cubic indium oxide.

5. The application according to claim 4, characterized in that, Step 3) specifically involves: The porous cubic In2O3 obtained in step 2) was dispersed in ethanol, and an aqueous solution of chloroplatinic acid was added dropwise. After stirring at room temperature for 2 hours, the mixture was heated to dryness, heated to 200℃ at a rate of 5℃ / min in a 10% H2 / Ar atmosphere, and calcined for 2 hours to obtain the supported catalyst Pt / PC-In2O3.

6. A method for producing hydrogen by aqueous reforming of methanol, characterized in that, The operation is as follows: The catalyst Pt / PC-In2O3 prepared by the preparation method described in any of claims 1-5 is uniformly dispersed in a mixed solution of water and methanol, and then transferred to a high-pressure reactor and purged with nitrogen to carry out the reaction at a temperature of 120-180°C. Hydrogen is obtained after the reaction is completed.

7. The method according to claim 6, characterized in that: The volume ratio of water to methanol is 9:20; The mass-to-volume ratio of the catalyst Pt / PC-In2O3 to the mixed solution of water and methanol was 25:29 mg / mL.

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