Preparation method and application of Au-loaded bismuth-based semiconductor photo-thermal catalyst

Abstract

The invention provides a preparation method and application of an Au-loaded bismuth-based semiconductor photothermal catalyst, and relates to the technical field of catalysts, a Bi-based precursor is prepared, and the Bi-based precursor is any one of BiVO4, Bi2WO6, BiOCl, BiOBr, BiOI, Bi2MoO6 and Bi2O3; loading Au onto the Bi-based precursor by adopting a homogeneous reduction method, a deposition-precipitation method, a photodeposition method or an Au sputtering method to obtain an Au-loaded bismuth-based catalytic material; and loading the Au-loaded bismuth-based catalytic material on 0.1-10mm quartz microspheres by adopting an initial wet impregnation method, and carrying out vacuum drying on the quartz microspheres to obtain the Au-loaded bismuth-based semiconductor photo-thermal catalyst for the reaction of preparing ethane by photo-thermal synergistic catalysis of methane coupling.

Description

Technical Field

[0001] The present application relates to the field of catalyst technology, and in particular to a preparation method and application of an Au-loaded bismuth-based semiconductor photothermal catalyst. Background Art

[0002] In the process of preparing ethane products by coupling methane molecules through the method of photothermal synergistic catalysis, the high-energy charge carriers generated by photon energy excitation can pre-activate methane, thereby greatly reducing the activation energy of the reaction; thermal catalysis can greatly improve the conversion rate and selectivity of reaction intermediates to final products, thereby improving the overall conversion rate and selectivity of the catalytic reaction. Therefore, the one-step preparation of C2 products by photon and thermal phonon synergistic catalytic methane conversion has important research value and application prospects.

[0003] However, the related art lacks a catalyst suitable for the photothermal catalytic methane coupling reaction to prepare ethane, so as to achieve a high methane conversion rate and high ethane selectivity in the process of converting methane to ethane. Summary of the invention

[0004] In view of the above problems, the embodiments of the present application provide a method for preparing and applying an Au-loaded bismuth-based semiconductor photothermal catalyst to achieve high methane conversion rate and high ethane selectivity in the process of photothermal synergistic catalytic conversion of methane to ethane.

[0005] In a first aspect of an embodiment of the present application, a method for preparing an Au-supported bismuth-based semiconductor photothermal catalyst is provided, the preparation method comprising:

[0006] Prepare a Bi-based precursor, wherein the Bi-based precursor is any one of the following: BiVO4, Bi2WO6, BiOCl, BiOBr, BiOI, Bi2MoO6, Bi2O3;

[0007] Using a homogeneous reduction method, a deposition-precipitation method, a photodeposition method or an Au sputtering method, Au is loaded onto the Bi-based precursor to obtain an Au-loaded bismuth-based catalytic material;

[0008] The Au-loaded bismuth-based catalytic material is loaded onto 0.1-10 mm quartz microspheres by an incipient wetness impregnation method, and the quartz microspheres are vacuum dried to obtain an Au-loaded bismuth-based semiconductor photothermal catalyst for the photothermal synergistic catalytic methane coupling reaction to prepare ethane.

[0009] In a possible implementation, when the Bi-based precursor is BiVO4, the preparation of the Bi-based precursor includes:

[0010] Bi(NO3)3·5H2O was added into deionized water and stirred by ultrasonic to obtain a first uniform solution;

[0011] While the first uniform solution is continuously stirred, Na3VO4·12H2O is added to the first uniform solution at one time, and the solution is continuously stirred for 30 minutes to obtain a uniform yellow suspension;

[0012] The yellow suspension is transferred to a high pressure hydrothermal autoclave, heated at 100-180°C for 2-12 hours, and then centrifuged to obtain a first precipitate;

[0013] The first precipitate was washed with deionized water, and the washed first precipitate was vacuum dried at 60° C. for 12 hours to obtain the Bi-based precursor.

[0014] In a possible implementation, when the Bi-based precursor is BiOCl, BiOBr or BiOI, the preparation of the Bi-based precursor includes:

[0015] Add bismuth chloride, bismuth bromide or bismuth iodide to octadecene, stir evenly, then add oleylamine and oleic acid, continue stirring until the solution is evenly mixed, to obtain a second uniform solution;

[0016] The second homogeneous solution was placed under vacuum at 100° C. for 4 h for degassing, and then argon gas was introduced to balance the pressure;

[0017] The second homogeneous solution is transferred to an autoclave, subjected to a solvothermal reaction at 100-180° C. for 1-6 hours, and after cooling to room temperature, centrifuged to obtain a second precipitate;

[0018] The second precipitate is washed with a mixed solution of n-hexane and isopropanol, and the washed second precipitate is freeze-dried for 24 hours to obtain the Bi-based precursor.

[0019] In a possible implementation, when the Bi-based precursor is Bi2WO6, the preparation of the Bi-based precursor includes:

[0020] Bi(NO3)3·5H2O, Na2WO4·2H2O and hexadecyltrimethylammonium chloride were added to 50 mL of deionized water, and the solution was mixed uniformly after ultrasonication for 10 min and stirring for 30 min to obtain a third uniform solution;

[0021] The third uniform solution is transferred to an autoclave, heated at 100-180° C. for 1-12 hours, and then naturally cooled to room temperature to obtain a third precipitate;

[0022] The third precipitate was washed with deionized water and anhydrous ethanol respectively, and the washed third precipitate was freeze-dried for 24 hours to obtain the Bi-based precursor.

[0023] In a possible implementation, when the Bi-based precursor is Bi2MO6, the preparation of the Bi-based precursor includes:

[0024] Dissolve Bi(NO3)3·5H2O in ethylene glycol, stir and add Na2MoO4·2H2O to obtain a fourth uniform solution;

[0025] The fourth uniform solution is transferred to a hydrothermal reaction kettle, and reacted in a forced air drying oven at 100-180° C. for 1-12 hours to obtain a fourth precipitate;

[0026] The fourth precipitate was washed with deionized water and anhydrous ethanol respectively, and the washed fourth precipitate was dried in a forced air drying oven at 60° C. for 12 hours to obtain the Bi-based precursor.

[0027] In a possible implementation, the Au-loaded bismuth-based catalytic material is obtained by loading Au onto the Bi-based precursor using the homogeneous reduction method according to the following steps:

[0028] preparing a gold source solution, wherein the gold source solution is chloroauric acid solution, sodium tetrachloroaurate solution or potassium tetrachloroaurate solution;

[0029] Adding the Bi-based precursor into deionized water and stirring by ultrasonic to obtain a first suspension;

[0030] Adding the gold source solution to the first suspension, and adding NaBH4, and continuously stirring to obtain a first reaction precipitate;

[0031] The first reaction precipitate was washed with deionized water, and the washed first reaction precipitate was vacuum dried at 60° C. for 12 hours to obtain the Au-loaded bismuth-based catalytic material.

[0032] In a possible implementation, the deposition-precipitation method is used to load Au onto the Bi-based precursor to obtain the Au-loaded Bi-based catalytic material according to the following steps:

[0033] preparing a gold source solution, wherein the gold source solution is chloroauric acid solution, sodium tetrachloroaurate solution or potassium tetrachloroaurate solution;

[0034] Adding the Bi-based precursor into deionized water and stirring by ultrasonic to obtain a second suspension;

[0035] Adding the gold source solution to the second suspension, adjusting the pH of the second suspension to a range of 8-10 using sodium hydroxide, ammonia water or sodium carbonate, standing the suspension, centrifuging, washing and drying the suspension in sequence to obtain a second reaction precipitate;

[0036] The second reaction precipitate is calcined at 300° C. for 2-8 hours in an air atmosphere to obtain the Au-supported bismuth-based catalytic material.

[0037] In a possible implementation, Au is loaded onto the Bi-based precursor using the photodeposition method according to the following steps to obtain the Au-loaded Bi-based catalytic material:

[0038] Adding the Bi-based precursor into a methanol solution and stirring the solution by ultrasonic to obtain a precursor colloid;

[0039] In the dark, a gold source solution is prepared, wherein the gold source solution is a chloroauric acid solution, a sodium tetrachloroaurate solution or a potassium tetrachloroaurate solution;

[0040] Under dark conditions, adding the gold source solution to the precursor colloid, and irradiating with an LED light source for 1-30 minutes to obtain a third reaction precipitate;

[0041] The third reaction precipitate is washed with deionized water, and the washed third reaction precipitate is vacuum dried at 60° C. for 12 hours to obtain the Au-loaded bismuth-based catalytic material.

[0042] In a possible implementation, the Au-supported bismuth-based catalytic material is obtained by using the Au sputtering method to load Au onto the Bi-based precursor according to the following steps:

[0043] Adding the Bi-based precursor into deionized water and subjecting it to ultrasonic treatment to obtain a third suspension;

[0044] Using an ultra-fine glass fiber microporous membrane to filter the third suspension to obtain a precursor membrane;

[0045] The precursor film was placed in a forced air drying oven at 60° C. and dried for 12 h;

[0046] Under an argon atmosphere, Au is sputtered onto the precursor film using a sputtering machine, and the sputtering time is 30-600s to obtain the Au-loaded bismuth-based catalytic material.

[0047] The second aspect of the embodiment of the present application proposes an application of an Au-supported bismuth-based semiconductor photothermal catalyst, which is used for the photothermal synergistic catalytic methane coupling reaction to prepare ethane, and ethane is prepared by using methane, dry air and water at a reaction temperature within 25-500°C. The Au-supported bismuth-based semiconductor photothermal catalyst is prepared by the preparation method of the Au-supported bismuth-based semiconductor photothermal catalyst described in the first aspect of the embodiment of the present application. .

[0048] The embodiment of the present application proposes a preparation method and application of an Au-loaded bismuth-based semiconductor photothermal catalyst, preparing a Bi-based precursor, wherein the Bi-based precursor is any one of the following: BiVO4, Bi2WO6, BiOCl, BiOBr, BiOI, Bi2MoO6, Bi2O3; using a homogeneous reduction method, a deposition-precipitation method, a photodeposition method or an Au sputtering method, Au is loaded onto the Bi-based precursor to obtain an Au-loaded bismuth-based catalytic material; using an incipient wetness impregnation method, the Au-loaded bismuth-based catalytic material is loaded onto 0.1-10 mm quartz microspheres, and the quartz microspheres are vacuum dried to obtain a bismuth-based semiconductor photothermal catalyst for the Au load.

[0049] The specific beneficial effect is that: the embodiment of the present application proposes a method for preparing an Au-loaded bismuth-based semiconductor photothermal catalyst, and the prepared Au-loaded bismuth-based semiconductor photothermal catalyst is used for the photothermal synergistic catalytic methane coupling reaction to prepare ethane, which can efficiently convert methane into ethane under medium and low temperature environments, and the ethane selectivity is >80%. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0051] Figure 1 This is a flow chart of the steps of a method for preparing an Au-loaded bismuth-based semiconductor photothermal catalyst provided in one embodiment of the present application;

[0052] Figure 2 This is a TEM image of the Au / BiVO4 catalyst in Example 1 provided in one embodiment of the present application;

[0053] Figure 3 This is an EDS spectrum of the Au / BiVO4 catalyst in Example 1 provided in one embodiment of the present application;

[0054] Figure 4 This is an XRD diagram of a BiVO4 precursor and Au / BiVO4 catalyst in Example 1 provided in one embodiment of the present application;

[0055] Figure 5 This is a UV-vis DRS diagram of a BiVO4 precursor and Au / BiVO4 catalyst in Example 1 provided in one embodiment of the present application;

[0056] Figure 6It is a Tauc plot of the BiVO4 precursor and Au / BiVO4 catalyst in Example 1 obtained by UV-vis DRS provided in one embodiment of the present application;

[0057] Figure 7 This is a steady-state PL spectrum test diagram of a catalyst in Example 1 provided in one embodiment of the present application;

[0058] Figure 8 This is a catalytic performance comparison diagram of a BiVO4 precursor and a catalyst provided in an embodiment of the present application;

[0059] Fig. 9 This is a performance comparison diagram of a catalyst before and after illumination provided by an embodiment of the present application;

[0060] Fig.10 This is a catalytic performance diagram of a catalyst in Example 1 at different reaction temperatures provided by an embodiment of the present application;

[0061] Fig.11 This is a schematic diagram of the catalytic performance of a catalyst under different Au loading modes provided in an embodiment of the present application;

[0062] Fig.12 This is a catalyst performance comparison chart of different bismuth-based catalysts provided in an embodiment of the present application. DETAILED DESCRIPTION

[0063] The exemplary embodiments of the present application will be described in more detail below in conjunction with the accompanying drawings in the embodiments of the present application. Although the exemplary embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present application and to enable the scope of the present application to be fully communicated to those skilled in the art.

[0064] With the increasing consumption of fossil fuels and environmental pollution, people are increasingly in need of new clean energy. Methane (associated gas), as an important source of raw materials in the modern chemical industry, has attracted widespread attention due to its abundant reserves. Among them, the exploration of direct conversion of methane into high-value chemicals is the most eye-catching. Among various methane conversion reactions, the coupling of methane molecules to produce C2 products is one of the most common and cost-effective processes. Methane molecules have stable chemical properties. Traditional thermal catalytic conversion requires harsh reaction conditions and strong oxidants, and it is a two-step process to prepare C2 through syngas intermediates, so it is an energy-intensive industry. At the same time, due to the high reaction temperature, the catalyst sintering and coking are serious, and irreversible over-oxidation is difficult to avoid. Photocatalysis is a promising alternative to traditional thermal catalysis. It uses photons instead of heat energy to drive chemical processes, allowing catalytic reactions to be carried out under very mild conditions. However, this process is a thermodynamically unfavorable reaction. Despite the participation of high-energy charge carriers excited by photons, the conversion rate is always very low. Therefore, designing and developing a photothermal synergistic catalytic system to efficiently and selectively convert methane into high-value chemicals is an urgent development direction and difficulty that needs to be solved in this field.

[0065] A large number of experimental studies have shown that high-energy charge carriers generated by photon energy excitation can pre-activate methane, thereby significantly reducing the activation energy of the reaction; at the same time, thermal catalysis can greatly improve the conversion rate and selectivity of reaction intermediates to final products, thereby improving the overall conversion rate and selectivity of the catalytic reaction. Therefore, the one-step preparation of C2 products by the coordinated catalytic conversion of methane by photons and thermal phonons has important research value and application prospects.

[0066] However, the related art lacks a catalyst suitable for the photothermal catalytic methane coupling reaction to prepare ethane, so as to achieve a high methane conversion rate and high ethane selectivity in the process of converting methane to ethane.

[0067] In recent years, bismuth-based materials have been widely studied in the field of photocatalysis. Because the Bi6s and O2p orbitals in Bi(III) can hybridize to produce new hybrid VBs, thereby narrowing the band gap of bismuth-based materials, they exhibit strong light absorption in the visible light region. And bismuth-based semiconductor materials have attracted widespread attention in the field of photocatalysis due to their suitable band gap, deep oxidation potential and high photochemical stability. For example, ultrathin two-dimensional BiVO4 nanosheets with a monoclinic crystal structure have a diameter greater than 1.2 μm, a thickness less than 3 nm, and abundant oxygen vacancies on the surface, which significantly improves the photocatalytic activity. The internal electric field (IEF) between the two main crystal planes of Bi2WO6 can promote the asymmetric polarization effect of photocharges, thereby activating more molecular oxygen. In addition, the atomically thick BiOX (X=Cl, Br, I) two-dimensional nanostructure can shorten the carrier diffusion distance, reduce the recombination of photogenerated electrons-holes, and thus improve electron transport, and the two-dimensional nanostructure also helps to recombine with other active components.

[0068] In view of the above problems, the present application proposes a method for preparing and applying an Au-loaded bismuth-based semiconductor photothermal catalyst, so as to achieve high methane conversion rate and high ethane selectivity in the process of photothermal synergistic catalytic conversion of methane to ethane. The following is a detailed description of the method for preparing and applying an Au-loaded bismuth-based semiconductor photothermal catalyst provided in the present application in combination with the accompanying drawings through some embodiments and their application scenarios.

[0069] The first aspect of the present application proposes a method for preparing an Au-loaded bismuth-based semiconductor photothermal catalyst. Figure 1 , Figure 1 A flow chart showing the steps of a method for preparing an Au-supported bismuth-based semiconductor photothermal catalyst is shown, Figure 1 As shown, the preparation method of the Au-supported bismuth-based semiconductor photothermal catalyst includes:

[0070] Step S101, preparing a Bi-based precursor, wherein the Bi-based precursor is any one of the following: BiVO4, Bi2WO6, BiOCl, BiOBr, BiOI, Bi2MoO6, Bi2O3.

[0071] In this embodiment, the obtained Bi-based precursor can be a Bi-based compound Bi having a nano-scale flake or nano-particle structure. a Y b O c; Wherein, a represents the atomic coefficient ratio of Bi atoms, 1≥a≥2; Y represents V, W, Mo and X (X=Cl, Br, I) elements; b represents the atomic coefficient ratio of Y atoms, 0≥b≥2; c represents the atomic coefficient ratio of O atoms, 1≥c≥6; the Bi-based precursor can be: BiVO4, Bi2WO6, BiOX (X=Cl, Br, I), Bi2MoO6, Bi2O3, etc. Optionally, the structure of the Bi-based precursor prepared in the embodiment of the present application can be a nanoscale lamellar structure or a nanoparticle structure, and the thickness of the lamellar structure is 5nm. Among them, the structure of the Bi-based precursors of BiVO4, Bi2WO6, BiOX (X=Cl, Br, I) is a nanoscale lamellar structure, and the structure of the Bi-based precursors of Bi2MoO6 and Bi2O3 is a nanoparticle structure.

[0072] Step S102, using a homogeneous reduction method, a deposition-precipitation method, a photodeposition method or an Au sputtering method, Au is loaded onto the Bi-based precursor to obtain an Au-loaded bismuth-based catalytic material.

[0073] In the present application, Au is loaded on a Bi-based precursor. The Bi-based precursor as a carrier may have a nano-scale sheet structure or a nano-particle structure. Au metal clusters are evenly distributed on the Bi-based precursor, thereby improving the catalytic activity.

[0074] In this embodiment, the Au loading amount in the Au-loaded bismuth-based semiconductor photothermal catalyst is 0.1-5 wt.%, which means that the mass fraction of the Au element in the Au-loaded bismuth-based catalytic material is in the range of 0.1-5%.

[0075] Step S103, using the incipient wetness impregnation method, the Au-loaded bismuth-based catalytic material is loaded onto 0.1-10 mm quartz microspheres, and the quartz microspheres are vacuum dried to obtain an Au-loaded bismuth-based semiconductor photothermal catalyst for the photothermal synergistic catalytic methane coupling reaction to prepare ethane.

[0076] Optionally, the 0.1-10 mm quartz microspheres are vacuum dried, including: placing the impregnated quartz microspheres in an oven and vacuum drying them at 60° C. for 12 hours to obtain quartz microspheres loaded with Au-loaded bismuth-based catalytic materials (e.g., Au / BiVO4), i.e., the Au-loaded bismuth-based semiconductor photothermal catalyst. The embodiment of the present application enables the reaction gas to efficiently and effectively contact the catalyst while ensuring that light is fully utilized by the catalyst, and is also easy to load in the reactor by loading the Au-loaded bismuth-based catalytic material on the quartz microspheres.

[0077] Optionally, the particle size of the quartz microspheres may be 3 mm.

[0078] The specific photothermal catalytic methane coupling reaction process for preparing ethane can be: perform step S201, load Au-loaded bismuth-based semiconductor photothermal catalyst (3mm quartz microspheres) in a continuous flow reactor, and perform photothermal catalytic methane coupling reaction for preparing ethane. The filling thickness of the 3mm quartz microspheres is 2cm. The relevant reaction parameters of the photothermal catalytic methane coupling reaction for preparing ethane include: the reaction space velocity range is 1000-20000h -1 The reaction temperature range is 25-500℃, the reaction pressure range is 0.1-3MPa, nitrogen is used as the diluent gas, and the reaction ratio of methane, water and synthetic air is 0-3Mpa. In addition, the light source used for the catalytic reaction is any indoor or outdoor light source, which can achieve a spectral range of 320-780nm and a light intensity of 10-5000mW / cm 2 of light energy output.

[0079] The embodiment of the present application discloses a method for preparing an Au-loaded bismuth-based semiconductor photothermal catalyst in the photon and thermal phonon synergistic catalytic coupling of methane to prepare ethane. The Au-loaded bismuth-based semiconductor photothermal catalyst prepared by the above steps (S101-S103): obtaining a bismuth-based semiconductor precursor; using a homogeneous reduction method, a deposition-precipitation method, a photodeposition method or an Au sputtering method, Au is loaded onto the bismuth-based semiconductor precursor, followed by washing and drying to obtain an Au-loaded bismuth-based catalytic material. Finally, the Au-loaded bismuth-based catalytic material is loaded onto 0.1-10mm quartz microspheres to obtain the Au-loaded bismuth-based semiconductor photothermal catalyst proposed in the embodiment of the present application. According to the above method, the prepared Au-loaded bismuth-based semiconductor photothermal catalyst (e.g., Au / BiVO4) can efficiently convert methane into ethane in a medium-low temperature reaction environment in the photothermal synergistic catalytic coupling of methane to prepare ethane, and the ethane selectivity is greater than 80%.

[0080] Since there are many possible Bi-based precursors, including BiVO4, Bi2WO6, BiOCl, BiOBr, BiOI, Bi2MoO6, and Bi2O3, different Bi-based precursors have different preparation methods (step S201). The following sections 1.1-1.4 describe the preparation methods of different Bi-based precursors.

[0081] 1.1 Preparation method of BiVO4 precursor:

[0082] Bismuth nitrate and sodium vanadate are hydrolyzed in an aqueous solution and hydrothermally crystallized at a temperature of 100-180° C. to synthesize a nanosheet BiVO4 precursor with a target thickness (eg, 5 nm thickness).

[0083] In a possible implementation, when the Bi-based precursor is BiVO4, the preparation of the Bi-based precursor includes:

[0084] Step S301, add Bi(NO3)3·5H2O to deionized water, and stir by ultrasonic to obtain a first uniform solution. Specifically, add 1g Bi(NO3)3·5H2O to every 600mL deionized water, and stir by ultrasonic until the solution is uniform.

[0085] Step S302, while the first homogeneous solution is continuously stirred, Na3VO4·12H2O is added to the first homogeneous solution at one time, and the mixture is continuously stirred for 30 minutes to obtain a uniform yellow suspension. Specifically, under vigorous stirring, Na3VO4·12H2O (2 g of Na3VO4·12H2O is added to every 600 mL of the first homogeneous solution) is rapidly added to the first homogeneous solution at one time, and the mixture is continuously stirred for 30 minutes until a uniform yellow suspension is obtained.

[0086] Step S303, transferring the yellow suspension to a high-pressure hydrothermal autoclave, heating at 100-180°C for 2-12h, and centrifuging to obtain a first precipitate. Specifically, the yellow suspension is transferred to a 100mL high-pressure hydrothermal autoclave, heated at 100-180°C for 2-12h, and centrifuged to obtain the precipitate to obtain a first precipitate. The thickness of the sheet structure of the Bi-based precursor obtained is different depending on the corresponding heating time. In this embodiment, the heating time is 2-12h to control the sheet thickness of the Bi-based precursor to be about 5mm.

[0087] Step S304, washing the first precipitate with deionized water, and vacuum drying the washed first precipitate at 60°C for 12 hours to obtain the Bi-based precursor. Specifically, washing with deionized water three times, placing the washed sample in an oven at 60°C for 12 hours in vacuum, and obtaining the BiVO4 precursor after drying.

[0088] The embodiment of the present application uses a homogeneous reduction method using NaBH4 as a reducing agent to prepare a BiVO4 precursor. This method has simple process, mild reaction, good repeatability, and does not require high temperature and high pressure reaction conditions and high temperature reduction in an active atmosphere, which reduces the synthesis time and cost, is economically and environmentally friendly, and has dual benefits.

[0089] 1.2 Preparation of BiOX (X = Cl, Br, I) precursor:

[0090] In a possible implementation, when the Bi-based precursor is BiOCl, BiOBr or BiOI, the preparation of the Bi-based precursor includes:

[0091] Step S401, add bismuth chloride, bismuth bromide or bismuth iodide to octadecene, stir evenly, add oleylamine and oleic acid, continue stirring until the solution is evenly mixed, and obtain a second uniform solution. Specifically, add 2.7 mmol bismuth chloride, bismuth bromide or bismuth iodide to every 40.5 mL octadecene, stir evenly, then add 3.60 mL oleylamine and 3.60 mL oleic acid, and continue stirring until the solution is evenly mixed.

[0092] Step S402, degas the second uniform solution under vacuum conditions at 100°C for 4 hours, and then introduce argon gas to balance the pressure. Specifically, vacuum degassing is performed to remove low boiling point impurities, and then argon gas is introduced to balance the pressure.

[0093] Step S403, transferring the second uniform solution to an autoclave, performing a solvent thermal reaction at 100-180° C. for 1-6 hours, and after cooling to room temperature, centrifuging to obtain a second precipitate. Specifically, after degassing, the second uniform solution is quickly transferred to a 30 mL autoclave, performing a solvent thermal reaction at 100-180° C. for 1-6 hours. After the autoclave is naturally cooled to room temperature (e.g., 20° C.), the product is collected by centrifugation.

[0094] Step S404, washing the second precipitate with a mixed solution of n-hexane and isopropanol, freeze-drying the washed second precipitate for 24 hours to obtain the Bi-based precursor. Specifically, washing the second precipitate with a mixed solution of n-hexane and isopropanol three times. Finally, freeze-drying the obtained product for 24 hours to obtain BiOCl nano precursors of different thicknesses.

[0095] In this embodiment, bismuth chloride is replaced by bismuth bromide to prepare a BiOBr nano-precursor; correspondingly, bismuth chloride is replaced by bismuth iodide to prepare a BiOI nano-precursor.

[0096] 1.3 Preparation method of Bi2WO6 precursor:

[0097] In a possible implementation, when the Bi-based precursor is Bi2WO6, the preparation of the Bi-based precursor includes:

[0098] Step S501, add Bi(NO3)3·5H2O, Na2WO4·2H2O and hexadecyltrimethylammonium chloride to 50 mL of deionized water, stir for 30 minutes after ultrasonic treatment for 10 minutes to mix the solution evenly, and obtain a third uniform solution. Specifically, add 0.20 g Bi(NO3)3·5H2O, 0.60 g Na2WO4·2H2O and 0.03 g hexadecyltrimethylammonium chloride to each 50 mL of deionized water, stir for 30 minutes after ultrasonic treatment for 10 minutes to mix the solution evenly, and obtain a third uniform solution.

[0099] Step S502, transferring the third uniform solution into an autoclave, heating at 100-180°C for 1-12 hours, and then naturally cooling to room temperature to obtain a third precipitate.

[0100] Step S503, washing the third precipitate with deionized water and anhydrous ethanol respectively, freeze-drying the washed third precipitate for 24 hours to obtain the Bi-based precursor.

[0101] 1.4 Preparation method of Bi2MO6 precursor:

[0102] In a possible implementation, when the Bi-based precursor is Bi2MO6, the preparation of the Bi-based precursor includes:

[0103] Step S601, dissolving Bi(NO3)3·5H2O in ethylene glycol, stirring and then adding Na2MoO4·2H2O to obtain a fourth uniform solution. Specifically, 1 mmol of Bi(NO3)3·5H2O is added to every 18 mL of ethylene glycol, stirring at room temperature for 20 min and then adding 0.5 mmol of Na2MoO4·2H2O to obtain a fourth uniform solution.

[0104] Step S602, transferring the fourth uniform solution to a hydrothermal reaction kettle, reacting in a forced air drying oven at 100-180°C for 1-12 hours to obtain a fourth precipitate.

[0105] Step S603, washing the fourth precipitate with deionized water and anhydrous ethanol respectively, and drying the washed fourth precipitate in a 60° C. forced air drying oven for 12 hours to obtain the Bi-based precursor.

[0106] In addition, when the Bi-based precursor is Bi2O3, commercial bismuth oxide can be directly used and placed in an oven for vacuum drying at 60°C for 12 hours to obtain a Bi2O3 precursor.

[0107] In this embodiment, different methods (homogeneous reduction method, deposition-precipitation method, photodeposition method or Au sputtering method) can be used to load Au onto the Bi-based precursor (i.e., step S201). The following sections 2.1-2.3 respectively describe different loading methods:

[0108] 2.1 Homogeneous reduction method:

[0109] In a possible implementation, the Au-loaded bismuth-based catalytic material is obtained by loading Au onto the Bi-based precursor using the homogeneous reduction method according to the following steps:

[0110] Step S701, preparing a gold source solution, wherein the gold source solution is chloroauric acid solution, sodium tetrachloroaurate solution or potassium tetrachloroaurate solution.

[0111] Specifically, a 0.1 mol / L HCl solution was prepared, 500 mg HAuCl4·3H2O was added to every 50 ml HCl solution, and the mixture was stirred until uniformly mixed to prepare a gold source solution with a concentration of 5 mg (Au) / mL. It is still feasible to replace the gold source with sodium tetrachloroaurate or potassium tetrachloroaurate.

[0112] Step S702, adding the Bi-based precursor to deionized water, and stirring by ultrasonic to obtain a first suspension. Specifically, every 50 mg of Bi-based precursor is added to 50 ml of deionized water, ultrasonicated for 10 minutes, and continuously stirred for 20 minutes until uniformly dispersed.

[0113] Step S703, adding the gold source solution to the first suspension, and adding NaBH4, and continuously stirring to obtain a first reaction precipitate. Specifically, for every 50 mg of Bi-based precursor, 10-1000 μL of the gold source solution prepared in step S701 is added to the first suspension, and 1-50 mg of NaBH4 is quickly added, and continuously stirred for 60 min to obtain a first reaction precipitate.

[0114] Step S704, washing the first reaction precipitate with deionized water, and vacuum drying the washed first reaction precipitate at 60° C. for 12 hours to obtain the Au-loaded bismuth-based catalytic material.

[0115] Specifically, the first reaction precipitate is washed three times with deionized water, and the washed first reaction precipitate is placed in an oven at 60°C for vacuum drying for 12 hours, and after drying, an Au-loaded bismuth-based catalytic material, such as an Au / BiVO4 catalyst, is obtained. According to the addition of different volumes of gold source solution, an Au-loaded bismuth-based catalytic material with an Au mass fraction within 0.1 to 5wt% can be prepared. Moreover, the embodiment of the present application can accurately control the size, morphology and uniformity of the Au clusters by controlling the volume of the gold source solution added and the amount of NaBH4 used.

[0116] 2.2 Sedimentation-precipitation method:

[0117] In a possible implementation, the deposition-precipitation method is used to load Au onto the Bi-based precursor to obtain the Au-loaded Bi-based catalytic material according to the following steps:

[0118] Step S801, preparing a gold source solution, wherein the gold source solution is chloroauric acid solution, sodium tetrachloroaurate solution or potassium tetrachloroaurate solution.

[0119] Specifically, 500 mg HAuCl4·3H2O was added to every 50 ml of deionized water, and the mixture was stirred until uniformly mixed to prepare a gold source solution with a concentration of 5 mg (Au) / mL. It is still feasible to replace the gold source with sodium tetrachloroaurate or potassium tetrachloroaurate.

[0120] Step S802, adding the Bi-based precursor to deionized water, and stirring by ultrasonic to obtain a second suspension. Specifically, as in the above step S702, 50 mg of the Bi-based precursor is placed in 50 ml of deionized water, ultrasonicated for 10 minutes, and continuously stirred for 20 minutes until uniformly dispersed to obtain a second suspension.

[0121] Step S803, adding the gold source solution to the second suspension, adjusting the pH of the second suspension to a range of 8-10 using sodium hydroxide, ammonia water or sodium carbonate, and then centrifuging, washing and drying in sequence to obtain a second reaction precipitate. Specifically, 10-1000 μL of the gold source solution is added to every 50 ml of the second suspension, and the pH of the solution is adjusted to 8-10 using sodium hydroxide, ammonia water and sodium carbonate respectively, and then centrifuged, washed and dried to obtain a second reaction precipitate after the precipitation is obtained.

[0122] Step S804, calcining the second reaction precipitate at 300° C. for 2-8 hours in an air atmosphere to obtain the Au-loaded bismuth-based catalytic material. Exemplarily, Au / BiVO4 catalytic materials are prepared according to the above steps, and are named Au / BiVO4-1, Au / BiVO4-2, and Au / BiVO4-3, respectively. According to the addition of different volumes of gold source solution, Au / BiVO4 catalysts with Au mass fractions within 0.1 to 5wt% can be prepared.

[0123] 2.3 Photodeposition method:

[0124] In a possible implementation, Au is loaded onto the Bi-based precursor using the photodeposition method according to the following steps to obtain the Au-loaded Bi-based catalytic material:

[0125] Step S901, adding the Bi-based precursor to a methanol solution, and stirring by ultrasonication to obtain a precursor colloid. Specifically, 50 mg of Bi-based precursor is added to 20 ml of methanol, and ultrasonication and stirring are performed until the precursor colloid is uniformly dispersed.

[0126] Step S902, in the dark, prepare a gold source solution, wherein the gold source solution is a chloroauric acid solution, a sodium tetrachloroaurate solution or a potassium tetrachloroaurate solution. Specifically, in the dark, 500 mg of HAuCl4·3H2O is added to 50 ml of methanol and stirred until uniformly mixed to obtain a gold source solution with a concentration of 5 mg (Au) / mL. It is still feasible to replace the gold source with sodium tetrachloroaurate or potassium tetrachloroaurate. When the catalyst is prepared by the photodeposition method, in order to avoid interference from external light, the gold source solution and the preliminary preparation need to be carried out in the dark.

[0127] Step S903, under dark conditions, adding the gold source solution to the precursor colloid, irradiating with an LED light source for 1-30 minutes, to obtain a third reaction precipitate. Specifically, 10-1000 μL of the gold source solution is added to every 20 ml of the BiVO4 precursor colloid, and then irradiating with an LED light source for 1-30 minutes to obtain a third reaction precipitate.

[0128] Step S904, washing the third reaction precipitate with deionized water, and vacuum drying the washed third reaction precipitate at 60° C. for 12 hours to obtain the Au-supported bismuth-based catalytic material. Specifically, after washing with deionized water, placing the third reaction precipitate in an oven at 60° C. for vacuum drying for 12 hours, the Au-supported bismuth-based catalytic material, for example, Au / BiVO4, is obtained after drying.

[0129] 2.4Au sputtering method:

[0130] In a possible implementation, the Au-supported bismuth-based catalytic material is obtained by using the Au sputtering method to load Au onto the Bi-based precursor according to the following steps:

[0131] Step S1001, adding the Bi-based precursor to deionized water, and performing ultrasonic treatment to obtain a third suspension. Specifically, similar to the above step S702, every 200 mg of the Bi-based precursor is placed in 200 ml of deionized water, ultrasonicated for 20 minutes, and continuously stirred for 20 minutes until uniformly dispersed, to obtain a third suspension.

[0132] Step S1002, using an ultra-fine glass fiber microporous membrane to filter the third suspension to obtain a precursor membrane.

[0133] Step S1003, placing the precursor film in a forced air drying oven at 60°C and drying for 12 hours.

[0134] Step S1004, in an argon atmosphere, using a sputtering machine to sputter Au onto the precursor film, the sputtering time is 30-600s, to obtain the Au-loaded bismuth-based catalytic material.

[0135] Embodiment 1,

[0136] Example 1 is an example of preparing an Au-loaded bismuth-based semiconductor photothermal catalyst using a BiVO4 precursor and a homogeneous reduction method.

[0137] The following is the preparation process of the Au-supported bismuth-based semiconductor photothermal catalyst proposed in Example 1:

[0138] (1) Add 0.25g Bi(NO3)3·5H2O to 150mL deionized water, and then ultrasonically stir until the solution is uniform. Under vigorous stirring, quickly add 0.5g Na3VO4·12H2O to the solution at one time. Stir continuously for 30min until a uniform yellow suspension is obtained, then transfer it to a 100mL high-pressure hydrothermal autoclave and heat it at 100-180℃ for 2-12h. Centrifuge the resulting precipitate and wash it three times with deionized water. Place the washed sample in an oven at 60℃ and vacuum dry it for 12h. After drying, a 5nm thick BiVO4 precursor (corresponding to step S201) is obtained.

[0139] (2) Prepare a 0.1 mol / L HCl solution, take 50 ml of the HCl solution, add 500 mg of HAuCl4·3H2O, and stir until the mixture is uniformly mixed to prepare a gold source solution with a concentration of 5 mg (Au) / mL.

[0140] (3) Place 50 mg of the 5 nm thick BiVO4 precursor in (1) in 50 ml of deionized water, ultrasonicate for 10 min, and stir continuously for 20 min until it is evenly dispersed. Take 10-1000 μL of the gold source solution prepared in step (2) and add it to the mixed liquid, and quickly add 1-50 mg NaBH4 and continue stirring for 60 min. After stirring, wash it three times with deionized water, place the washed sample in an oven at 60°C and vacuum dry it for 12 h, and after drying, Au / BiVO4 (i.e., the Au-loaded bismuth-based catalytic material prepared in step S202) is obtained. In this embodiment, the mass fraction of Au can be 1%.

[0141] (4) Through step S203, Au / BiVO4 is loaded onto 0.1-10 mm quartz microspheres by using the incipient wetness impregnation method, and the quartz microspheres are vacuum dried to obtain the bismuth-based semiconductor photothermal catalyst for the Au loading.

[0142] The Au / BiVO4 catalyst prepared in Example 1 has an ethane selectivity of 85% at 200°C, under Xe lamp irradiation, and methane:synthetic air=60ml / min:3ml / min (i.e., the concentration ratio of methane to oxygen is 100:1). The BiVO4 precursor and 1wt.% Au / BiVO4 catalyst in Example 1 were subjected to transmission electron microscopy (TEM) morphology test, X-ray diffraction (XRD) structure test, and ultraviolet visible spectrophotometer (UV-Vis) test. Figure 2 A transmission electron microscope (TEM) image of the Au / BiVO4 catalyst in Example 1 is shown. Figure 3 The energy dispersive spectrometer (EDS) spectrum of the Au / BiVO4 catalyst in Example 1 is shown. Figure 4 The X-ray diffraction (XRD) diagram of the BiVO4 precursor and the Au / BiVO4 catalyst in Example 1 is shown. Figure 5 The figure shows the ultraviolet visible diffuse reflectance spectrum (UV-Vis DRS) of the BiVO4 precursor and Au / BiVO4 catalyst in Example 1. Figure 6 The semiconductor band gap Tauc diagram of the BiVO4 precursor and Au / BiVO4 catalyst in Example 1 obtained by UV-vis DRS is shown.

[0143] Depend on Figure 2 It can be seen that the BiVO4 carrier is in the form of flakes with a size of 25-30nm; the Au metal nanoclusters are evenly distributed on the BiVO4 flakes, and the size of the Au clusters is about 1nm; the EDS spectrum of the 1wt.% Au / BiVO4 catalyst ( Figure 3 ) shows that various elements are evenly distributed. Comparing the distribution of Au elements with that of Bi, V, and O elements, it is also proved that Au metal nanoclusters are evenly distributed on the BiVO4 sheet.

[0144] Figure 4 The figure is the powder X-ray diffraction (XRD) diagram of the catalyst sample. As shown in the figure, the characteristic diffraction peaks of the BiVO4 precursor and the 1wt.% Au / BiVO4 catalyst match those of the tetragonal BiVO4, thus proving that the structure of the tetragonal BiVO4 catalyst does not change before and after the homogeneous reduction using NaBH4 as a reducing agent. Figure 3 There is no obvious characteristic peak of Au in Figure 1 This is because the Au loading is 1 wt.% and the particle size is about 1 nm, which is lower than the detection limit of XRD.

[0145] Figure 5From the UV-vis diffuse reflectance spectroscopy (DRS) characterization of the catalyst samples, it can be seen that the 1wt.% Au / BiVO4 catalyst has an obvious Urbach tailing absorption compared to the BiVO4 precursor, indicating that the Au / BiVO4 catalyst prepared by the homogeneous reduction method using NaBH4 as a reducing agent has better absorbance. Figure 6 The DRS of the catalyst sample is used to calculate its band gap energy according to formula (1) and formula (2).

[0146] αhvυ=A(hυ-E g ) 1 / 2 ………………………………(1)

[0147] E VB =E g +E CB ……………………………………(2)

[0148] Among them, α is the absorption constant, h is Planck's constant, v is the light frequency, E g is the band gap energy. After calculation, the E g They are 2.48eV and 2.42eV respectively.

[0149] Figure 7 This is a steady-state PL spectrum test diagram of the catalyst in Example 1, with an excitation wavelength of 320 nm. Figure 7 As shown, the PL intensity of the 1wt.% Au / BiVO4 catalyst prepared by homogeneous reduction method is significantly reduced, indicating that its photogenerated electrons have a higher separation efficiency.

[0150] Embodiment 2,

[0151] Example 2 is an example of preparing an Au-loaded bismuth-based semiconductor photothermal catalyst using a BiOCl precursor and a homogeneous reduction method.

[0152] The following is the preparation process of the Au-supported bismuth-based semiconductor photothermal catalyst proposed in Example 2:

[0153] (1) Add 40.5 mL of octadecene and 0.85 g (2.7 mmol) of bismuth chloride to a 500 mL flask, stir well, then add 3.60 mL of oleylamine and 3.60 mL of oleic acid, and continue stirring until the solution is mixed well. Degas the flask under vacuum conditions at 100 ° C for 4 h to remove low-boiling impurities, and then introduce argon into the flask to balance the air pressure. Subsequently, the mixed solution is quickly transferred to a 30 mL autoclave and solvothermally reacted at 100-180 ° C for 1-6 h. After the autoclave is naturally cooled to room temperature, the product is collected by centrifugation and washed three times with a mixed solution of n-hexane and isopropanol. Finally, the obtained product is freeze-dried for 24 h to obtain BiOCl nanosheet precursors of different thicknesses.

[0154] (2) First, prepare a 0.1 mol / L HCl solution, take 50 ml of the solution, add 500 mg HAuCl4·3H2O, and stir until the mixture is uniform to prepare a gold source solution with a concentration of 5 mg (Au) / mL. It is still feasible to replace the gold source with sodium tetrachloroaurate or potassium tetrachloroaurate.

[0155] (3) Place 50 mg of the 5 nm thick BiOCl precursor in (1) in 50 ml of deionized water, ultrasonicate for 10 min, and stir continuously for 20 min until it is evenly dispersed. Take 10-1000 μL of the gold source solution prepared in step 2 and add it to the mixed liquid, and quickly add 1-50 mg of NaBH4 and continue stirring for 60 min. After stirring, wash it three times with deionized water, place the washed sample in an oven at 60 ° C and vacuum dry it for 12 h. After drying, the Au / BiOCl catalyst with an Au mass fraction of 0.1 to 5 wt% is obtained.

[0156] (4) Through step S203, Au / BiOCl is loaded onto 0.1-10 mm quartz microspheres by using an incipient wetness impregnation method, and the quartz microspheres are vacuum dried to obtain a bismuth-based semiconductor photothermal catalyst for the Au loading.

[0157] By replacing the bismuth chloride in (1) with bismuth bromide and bismuth iodide, BiOBr and BiOI precursors can be obtained, and then Au / BiOBr and Au / BiOI catalytic materials can be prepared through steps (2) and (3). According to the addition of different volumes of gold source solution, Au / BiOX (X = Cl, Br, I) catalysts with Au mass fraction of 0.1 to 5wt% can be prepared.

[0158] Embodiment 3,

[0159] Example 3 is an example of preparing an Au-loaded bismuth-based semiconductor photothermal catalyst using a Bi2WO6 precursor and a homogeneous reduction method.

[0160] The following is the preparation process of the Au-supported bismuth-based semiconductor photothermal catalyst proposed in Example 3:

[0161] (1) 0.20 g Bi(NO3)3·5H2O, 0.60 g Na2WO4·2H2O and 0.03 g hexadecyltrimethylammonium chloride were added to 50 mL deionized water, and the solution was mixed evenly after ultrasonication for 10 min and stirring for 30 min. The mixed solution was then transferred to a 30 mL autoclave and heated at 100-180 °C for 1-12 h. After cooling naturally to room temperature, the product was washed several times with deionized water and anhydrous ethanol. Subsequently, the precipitate was freeze-dried for 24 h to obtain Bi2WO6 nanosheet precursors of different thicknesses.

[0162] (2) First, prepare a 0.1 mol / L HCl solution, take 50 ml of the solution, add 500 mg HAuCl4·3H2O, and stir until the mixture is uniform to prepare a gold source solution with a concentration of 5 mg (Au) / mL. It is still feasible to replace the gold source with sodium tetrachloroaurate or potassium tetrachloroaurate.

[0163] (3) Place 50 mg of the 5 nm thick Bi2WO6 precursor in (1) in 50 ml of deionized water, ultrasonicate for 10 min, and stir continuously for 20 min until it is evenly dispersed. Take 10-1000 μL of the gold source solution prepared in step 2 and add it to the mixed liquid, and quickly add 1-50 mg NaBH4 and continue stirring for 60 min. After stirring, wash it three times with deionized water, place the washed sample in an oven at 60°C and vacuum dry it for 12 h, and then you will get the Au / Bi2WO6 catalytic material after drying. According to the addition of different volumes of gold source solution, Au / Bi2WO6 catalytic materials with Au mass fraction of 0.1 to 5 wt% can be prepared.

[0164] (4) Through step S203, Au / Bi2WO6 is loaded onto 0.1-10 mm quartz microspheres by using the incipient wetness impregnation method, and the quartz microspheres are vacuum dried to obtain a bismuth-based semiconductor photothermal catalyst for the Au loading.

[0165] Embodiment 4,

[0166] Example 4 is an example of preparing an Au-loaded bismuth-based semiconductor photothermal catalyst using a Bi2O3 precursor and a homogeneous reduction method.

[0167] The following is the preparation process of the Au-supported bismuth-based semiconductor photothermal catalyst proposed in Example 4:

[0168] (1) Weigh 200 mg of commercial bismuth oxide and dry it in a vacuum oven at 60° C. for 12 h to obtain a bismuth oxide precursor.

[0169] (2) First, prepare a 0.1 mol / L HCl solution, take 50 ml of the solution, add 500 mg HAuCl4·3H2O, and stir until the mixture is uniform to prepare a gold source solution with a concentration of 5 mg (Au) / mL. It is still feasible to replace the gold source with sodium tetrachloroaurate or potassium tetrachloroaurate.

[0170] (3) Place 50 mg of the Bi2O3 precursor in (1) in 50 ml of deionized water, ultrasonicate for 10 min, and stir continuously for 20 min until it is evenly dispersed. Take 10-1000 μL of the gold source solution prepared in step 2 and add it to the mixed liquid, and quickly add 1-50 mg of NaBH4 and continue stirring for 60 min. After stirring, wash it three times with deionized water, place the washed sample in an oven at 60°C and vacuum dry it for 12 h, and then you will get the Au / Bi2O3 catalytic material after drying. According to the addition of different volumes of gold source solution, Au / Bi2O3 catalytic materials with Au mass fractions of 0.1 to 5 wt% can be prepared.

[0171] (4) Through step S203, Au / Bi2WO6 is loaded onto 0.1-10 mm quartz microspheres by using the incipient wetness impregnation method, and the quartz microspheres are vacuum dried to obtain a bismuth-based semiconductor photothermal catalyst for the Au loading.

[0172] Embodiment 5,

[0173] Example 5 is an example of preparing an Au-loaded bismuth-based semiconductor photothermal catalyst using a Bi2MO6 precursor and a homogeneous reduction method.

[0174] The following is the preparation process of the Au-supported bismuth-based semiconductor photothermal catalyst proposed in Example 5:

[0175] (1) Disperse and dissolve 1 mmol of Bi(NO3)3·5H2O in 18 mL of ethylene glycol, stir at room temperature for 20 min, and then add 0.5 mmol of Na2MoO4·2H2O. Then transfer the solution to a 30 mL hydrothermal reactor, and then place the reactor in a forced air drying oven at 100-180°C for 1-12 h. Wash the obtained solid with deionized water and ethanol three times respectively. Finally, dry the obtained solid in a forced air drying oven at 60°C for 12 h. After drying, the Bi2MO6 catalyst is obtained.

[0176] (2) First, prepare a 0.1 mol / L HCl solution, take 50 ml of the solution, add 500 mg HAuCl4·3H2O, and stir until the mixture is uniform to prepare a gold source solution with a concentration of 5 mg (Au) / mL. It is still feasible to replace the gold source with sodium tetrachloroaurate or potassium tetrachloroaurate.

[0177] (3) Place 50 mg of the Bi2MO6 precursor in (1) in 50 ml of deionized water, ultrasonicate for 10 min, and stir continuously for 20 min until it is evenly dispersed. Take 10-1000 μL of the gold source solution prepared in step 2 and add it to the mixed liquid, and quickly add 1-50 mg of NaBH4 (Sigma-Aldrich) and continue stirring for 60 min. After stirring, wash it three times with deionized water, place the washed sample in an oven at 60°C and vacuum dry it for 12 h, and then obtain the Au / Bi2MO6 catalyst. According to the addition of different volumes of gold source solution, Au / Bi2MO6 catalysts with Au mass fractions of 0.1 to 5 wt% can be prepared.

[0178] (4) Through step S203, Au / Bi2WO6 is loaded onto 0.1-10 mm quartz microspheres by using the incipient wetness impregnation method, and the quartz microspheres are vacuum dried to obtain a bismuth-based semiconductor photothermal catalyst for the Au loading.

[0179] Embodiment 6,

[0180] The performance of Au-loaded bismuth-based semiconductor photothermal catalyst was tested in the continuous flow photothermal synergistic catalytic reaction device. The device can achieve a spectral range of 320-780nm and a power of 10-5000mW / cm 2 Light intensity light energy output; 25-600℃ reaction temperature; using nitrogen as diluent gas, precise control of the reaction ratio of methane, water and synthetic air 0-3Mpa. Take 50mg of BiVO4 precursor and Au-loaded bismuth-based semiconductor photothermal catalyst proposed in the embodiment of this application and apply them on 3mm quartz microspheres. Under Xe lamp irradiation, methane: synthetic air = 60ml / min: 3ml / min, that is, the concentration ratio of methane to oxygen is controlled to 100:1, and the performance test is carried out at 200℃. Figure 8 The figure shows a comparison of the catalytic performance of a BiVO4 precursor and a catalyst, which is a catalytic performance diagram of a BiVO4 precursor and Au / BiVO4 catalysts with different Au loadings under the reaction conditions of 200°C and 1Mpa. Figure 8 It can be seen that when the Au loading is 1wt%, the Au / BiVO4 catalyst exhibits the best performance. Fig. 9 The figure shows a performance comparison of a catalyst before and after illumination, which is a performance comparison of a 1wt% Au / BiVO4 catalyst before and after illumination at 200°C and 1Mpa. Fig. 9 As shown in the figure, the ethane yield of Au / BiVO4 catalyst after loading Au increased by 0.38 mmol·h compared with BiVO4. -1 ·g -1 Increased to 5.20mmol·h -1 ·g -1, increased by 14 times, and the selectivity was also increased from the original 35.5% to 86.7%. In addition, when irradiated by Xe lamp, the ethane yield of Au / BiVO4 catalyst increased from 1.22mmol·h in dark reaction to 1.22mmol·h in dark reaction. -1 ·g -1 Increased to 5.20mmol·h -1 ·g -1 The selectivity increased from 67.1% to 86.7%, proving that the Au / BiVO4 catalyst prepared by the homogeneous reduction method using NaBH4 as a reducing agent has an obvious photoresponse and is an excellent photothermal synergistic catalytic catalyst for the conversion of methane to ethane.

[0181] Fig.10 The catalytic performance diagram of the catalyst in Example 1 at different reaction temperatures is shown in FIG. 1 , specifically, the catalytic performance diagram of 1wt% Au / BiVO4 catalyst at different reaction temperatures under Xe lamp irradiation, 1Mpa, methane:synthetic air=60ml / min:3ml / min. Fig.10 As shown, when the reaction temperature is 500°C, an ethane selectivity of 50% can be achieved. Fig.11 It is a schematic diagram of the catalytic performance of a catalyst under different Au loading modes, specifically a catalytic performance diagram of a 1wt% Au loading Au / BiVO4-a (a is 1-5) catalyst under Xe lamp irradiation, 200°C, 1Mpa, methane: synthetic air = 60ml / min: 3ml / min conditions). Fig.12 is a comparison chart of the catalyst performance of different bismuth-based catalysts, such as Fig.12 As shown, Au / bismuth semiconductor (Bi a Y b O c ) catalyst (Au loading was 1 wt%), and the catalyst performance was tested under Xe lamp irradiation, 200°C, 1 MPa, and methane:synthetic air=60 ml / min:3 ml / min reaction conditions.

[0182] As can be seen from the accompanying drawings and examples, the Au-loaded bismuth-based semiconductor photothermal catalyst of the present invention has good catalytic activity in the photothermal synergistic catalytic methane coupling to prepare ethane, wherein the Au / BiVO4 catalyst with 1 wt% Au loading is irradiated with a Xe lamp, 1 MPa, methane: synthetic air = 60 ml / min: 3 ml / min, and a reaction temperature of 200 ° C. The ethane yield is 5.20 mmol·h -1 ·g -1, the selectivity is 86.7%; and when the reaction temperature reaches 500°C, 50% ethane selectivity can be achieved. At the same time, the present invention verifies the Au-loaded bismuth-based semiconductor photothermal catalyst (Au / Bi a X b O c Catalyst), which proved that Au-loaded bismuth-based semiconductor photothermal catalysts have good catalytic activity in the photothermal synergistic catalytic methane coupling reaction to produce ethane. When the reaction temperature is 200°C, the ethane selectivity is higher than 80%, showing broad practical application prospects.

[0183] The second aspect of the embodiment of the present application proposes an application of an Au-loaded bismuth-based semiconductor photothermal catalyst, in which the Au-loaded bismuth-based semiconductor photothermal catalyst is used for the photothermal synergistic catalytic methane coupling reaction to prepare ethane. Ethane is prepared using methane, dry air and water at a reaction temperature within 25-500°C. The Au-loaded bismuth-based semiconductor photothermal catalyst is prepared by the preparation method of the Au-loaded bismuth-based semiconductor photothermal catalyst described in the first aspect of the embodiment of the present application.

[0184] In this embodiment, in the photon and thermal phonon catalytic methane to ethane reaction (i.e., photothermal catalytic methane coupling to ethane reaction), Au-loaded bismuth-based semiconductor photothermal catalyst (3 mm quartz microspheres) is loaded in a continuous flow reactor, and the loading thickness of the quartz microspheres is 2 cm. The relevant reaction parameters of the photothermal catalytic methane coupling to ethane reaction include: the reaction space velocity range is 1000-20000h -1 The reaction temperature range is 25-500℃, the reaction pressure range is 0.1-3MPa, nitrogen is used as the diluent gas, and the reaction ratio of methane, water and synthetic air is 0-3Mpa. In addition, the light source used for the catalytic reaction is any indoor or outdoor light source, which can achieve a spectral range of 320-780nm and a light intensity of 10-5000mW / cm 2 The Au-loaded bismuth-based semiconductor photothermal catalyst proposed in this embodiment exhibits an ethane selectivity greater than 80% when the reaction temperature is lower than 200°C; and can reach 50% ethane selectivity when the reaction temperature is 500°C.

[0185] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0186] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present application.

[0187] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0188] The above is a detailed introduction to the preparation method and application of an Au-loaded bismuth-based semiconductor photothermal catalyst provided by the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea; at the same time, for general technicians in this field, according to the ideas of the present application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for preparing an Au-supported bismuth-based semiconductor photothermal catalyst, characterized in that: Prepare a Bi-based precursor, wherein the Bi-based precursor is any one of the following: BiVO4, Bi2WO6, BiOCl, BiOBr, BiOI, Bi2MoO6, Bi2O3; Using a homogeneous reduction method, a deposition-precipitation method, a photodeposition method or an Au sputtering method, Au is loaded onto the Bi-based precursor to obtain an Au-loaded bismuth-based catalytic material; The Au-loaded bismuth-based catalytic material is loaded onto 0.1-10 mm quartz microspheres by an incipient wetness impregnation method, and the quartz microspheres are vacuum dried to obtain an Au-loaded bismuth-based semiconductor photothermal catalyst for the photothermal synergistic catalytic methane coupling reaction to prepare ethane.

2. The method for preparing the Au-supported bismuth-based semiconductor photothermal catalyst according to claim 1, characterized in that: In the case where the Bi-based precursor is BiVO4, the preparation of the Bi-based precursor comprises: Bi(NO3)3·5H2O was added into deionized water and stirred by ultrasonic to obtain a first uniform solution; While the first uniform solution is continuously stirred, Na3VO4·12H2O is added to the first uniform solution at one time, and the solution is continuously stirred for 30 minutes to obtain a uniform yellow suspension; The yellow suspension is transferred to a high pressure hydrothermal autoclave, heated at 100-180°C for 2-12 hours, and then centrifuged to obtain a first precipitate; The first precipitate was washed with deionized water, and the washed first precipitate was vacuum dried at 60° C. for 12 hours to obtain the Bi-based precursor.

3. The method for preparing the Au-supported bismuth-based semiconductor photothermal catalyst according to claim 1, characterized in that: In the case where the Bi-based precursor is BiOCl, BiOBr or BiOI, the preparation of the Bi-based precursor comprises: Add bismuth chloride, bismuth bromide or bismuth iodide to octadecene, stir evenly, then add oleylamine and oleic acid, continue stirring until the solution is evenly mixed, to obtain a second uniform solution; The second homogeneous solution was placed under vacuum at 100° C. for 4 h for degassing, and then argon gas was introduced to balance the pressure; The second homogeneous solution is transferred to an autoclave, subjected to a solvothermal reaction at 100-180° C. for 1-6 hours, and after cooling to room temperature, centrifuged to obtain a second precipitate; The second precipitate is washed with a mixed solution of n-hexane and isopropanol, and the washed second precipitate is freeze-dried for 24 hours to obtain the Bi-based precursor.

4. The method for preparing the Au-supported bismuth-based semiconductor photothermal catalyst according to claim 1, characterized in that: In the case where the Bi-based precursor is Bi2WO6, the preparation of the Bi-based precursor comprises: Bi(NO3)3·5H2O, Na2WO4·2H2O and hexadecyltrimethylammonium chloride were added to 50 mL of deionized water, and the solution was mixed uniformly after ultrasonication for 10 min and stirring for 30 min to obtain a third uniform solution; The third uniform solution is transferred to an autoclave, heated at 100-180° C. for 1-12 hours, and then naturally cooled to room temperature to obtain a third precipitate; The third precipitate is washed with deionized water and anhydrous ethanol respectively, and the washed third precipitate is freeze-dried for 24 hours to obtain the Bi-based precursor.

5. The method for preparing the Au-supported bismuth-based semiconductor photothermal catalyst according to claim 1, characterized in that: In the case where the Bi-based precursor is Bi2MO6, the preparation of the Bi-based precursor comprises: Dissolve Bi(NO3)3·5H2O in ethylene glycol, stir and add Na2MoO4·2H2O to obtain a fourth uniform solution; The fourth uniform solution is transferred to a hydrothermal reaction kettle, and reacted in a forced air drying oven at 100-180° C. for 1-12 hours to obtain a fourth precipitate; The fourth precipitate was washed with deionized water and anhydrous ethanol respectively, and the washed fourth precipitate was dried in a forced air drying oven at 60° C. for 12 hours to obtain the Bi-based precursor.

6. The method for preparing the Au-supported bismuth-based semiconductor photothermal catalyst according to claim 1, characterized in that: According to the following steps, Au is loaded onto the Bi-based precursor by the homogeneous reduction method to obtain the Au-loaded Bi-based catalytic material: preparing a gold source solution, wherein the gold source solution is chloroauric acid solution, sodium tetrachloroaurate solution or potassium tetrachloroaurate solution; Adding the Bi-based precursor into deionized water and stirring by ultrasonic to obtain a first suspension; Adding the gold source solution to the first suspension, and adding NaBH4, and continuously stirring to obtain a first reaction precipitate; The first reaction precipitate was washed with deionized water, and the washed first reaction precipitate was vacuum dried at 60° C. for 12 hours to obtain the Au-loaded bismuth-based catalytic material.

7. The method for preparing the Au-supported bismuth-based semiconductor photothermal catalyst according to claim 1, characterized in that: According to the following steps, Au is loaded onto the Bi-based precursor by the deposition-precipitation method to obtain the Au-loaded Bi-based catalytic material: preparing a gold source solution, wherein the gold source solution is chloroauric acid solution, sodium tetrachloroaurate solution or potassium tetrachloroaurate solution; Adding the Bi-based precursor into deionized water and stirring by ultrasonic to obtain a second suspension; Adding the gold source solution to the second suspension, adjusting the pH of the second suspension to a range of 8-10 using sodium hydroxide, ammonia water or sodium carbonate, standing the suspension, centrifuging, washing and drying the suspension in sequence to obtain a second reaction precipitate; The second reaction precipitate is calcined at 300° C. for 2-8 hours in an air atmosphere to obtain the Au-supported bismuth-based catalytic material.

8. The method for preparing the Au-supported bismuth-based semiconductor photothermal catalyst according to claim 1, characterized in that: According to the following steps, Au is loaded onto the Bi-based precursor by the photodeposition method to obtain the Au-loaded Bi-based catalytic material: Adding the Bi-based precursor into a methanol solution and stirring the solution by ultrasonic to obtain a precursor colloid; In the dark, a gold source solution is prepared, wherein the gold source solution is a chloroauric acid solution, a sodium tetrachloroaurate solution or a potassium tetrachloroaurate solution; Under dark conditions, adding the gold source solution to the precursor colloid, and irradiating with an LED light source for 1-30 minutes to obtain a third reaction precipitate; The third reaction precipitate is washed with deionized water, and the washed third reaction precipitate is vacuum dried at 60° C. for 12 hours to obtain the Au-loaded bismuth-based catalytic material.

9. The method for preparing the Au-supported bismuth-based semiconductor photothermal catalyst according to claim 1, characterized in that: According to the following steps, Au is loaded onto the Bi-based precursor by the Au sputtering method to obtain the Au-loaded bismuth-based catalytic material: Adding the Bi-based precursor into deionized water and subjecting it to ultrasonic treatment to obtain a third suspension; Using an ultra-fine glass fiber microporous membrane to filter the third suspension to obtain a precursor membrane; The precursor film was placed in a forced air drying oven at 60° C. and dried for 12 h; Under an argon atmosphere, Au is sputtered onto the precursor film using a sputtering machine, and the sputtering time is 30-600s to obtain the Au-loaded bismuth-based catalytic material.

10. An application of Au-supported bismuth-based semiconductor photothermal catalyst, characterized in that: The Au-loaded bismuth-based semiconductor photothermal catalyst is used for the photothermal synergistic catalytic methane coupling reaction to prepare ethane. Ethane is prepared using methane, dry air and water at a reaction temperature within 25-500°C. The Au-loaded bismuth-based semiconductor photothermal catalyst is prepared by the preparation method of the Au-loaded bismuth-based semiconductor photothermal catalyst described in any one of claims 1 to 9.

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