A metal-doped copper-based catalyst, its preparation method and application

Abstract

This invention discloses a metal-doped modified copper-based catalyst, its preparation method, and its application, belonging to the field of chemical hydrogen production technology. The preparation method of the metal-doped modified copper-based catalyst includes the following steps: dissolving a soluble copper salt, a soluble zinc salt, a soluble metal salt for doping modification, and a precipitant in ultrapure water, followed by isothermal aging, centrifugation, washing, drying, grinding, calcination, and reduction to obtain the metal-doped modified copper-based catalyst; wherein the soluble metal salt for doping modification includes at least one of gallium salt, indium salt, cerium salt, manganese salt, cobalt salt, magnesium salt, iron salt, nickel salt, or zirconium salt. In other words, this invention improves the photosensitivity of the copper-based catalyst by doping it with metal, thereby reducing the reaction temperature to suppress CO generation while significantly improving the photo-gain hydrogen production efficiency of the copper-based catalyst; and the CO concentration in the product during the MSR reaction is less than 10 ppm, meeting the requirements of downstream applications in the hydrogen fuel cell industry.

Description

Technical Field

[0001] This invention belongs to the field of chemical hydrogen production technology, and particularly relates to a copper-based catalyst modified with doped metal, its preparation method and application. Background Technology

[0002] Among numerous clean energy sources (solar, wind, bioenergy, hydropower, geothermal, hydrogen, etc.), H2 is considered the most promising energy source to replace traditional fossil fuels due to its extremely high energy density, zero pollution, and potential for use in downstream industries such as hydrogen fuel cells (passenger vehicles, generators, etc.). However, a key challenge in hydrogen fuel cells is that the electrode is easily poisoned by CO. The CO content in the hydrogen gas stream must be below 10 ppm; otherwise, the catalytic performance of the fuel cell will drop sharply. Therefore, the requirements for hydrogen concentration are extremely stringent.

[0003] Furthermore, the highly flammable and explosive nature of hydrogen is detrimental to its storage and transportation, hindering the large-scale use of hydrogen fuel cells. Liquid fuels are easier to store and transport and have a higher hydrogen-to-carbon ratio, making hydrogen production via steam reforming of alcohols (methanol, ethanol, propanol, etc.) a promising mobile hydrogen source. Methanol has a high hydrogen content (12.5%) and a relatively low reforming reaction temperature; therefore, hydrogen production based on methanol steam reforming (MSR) has been used commercially. However, currently commercially available copper-based catalysts, such as Cu / ZnO / Al2O3, have an activity temperature range of relatively high temperatures (220–280°C). In industrial MSR hydrogen production, to achieve higher economic efficiency, the reaction temperature is typically above 250°C to increase hydrogen yield. However, this temperature range exacerbates side reactions (reverse water-gas reactions), leading to increased CO content and decreased CO2 selectivity, which is detrimental to downstream applications in the hydrogen fuel cell industry.

[0004] While lowering the reaction temperature can suppress CO formation, it significantly reduces hydrogen yield. Introducing light energy into the thermocatalytic reaction can trigger the plasmon resonance effect in copper, thereby enhancing catalyst activity. This improves hydrogen production efficiency while lowering the reaction temperature, thus suppressing the reverse water-gas reaction and achieving the goals of reducing CO content and increasing CO2 selectivity. However, traditional copper-based catalysts suffer from a series of problems, including poor photosensitivity, insignificant light gain, and low hydrogen production efficiency. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a metal-doped modified copper-based catalyst, its preparation method, and its application.

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

[0007] One of the technical solutions of this invention:

[0008] A method for preparing a metal-doped modified copper-based catalyst, comprising using soluble copper salt, soluble zinc salt, and soluble metal salt for doping modification as precursors, and preparing the metal-doped modified copper-based catalyst by co-precipitation method;

[0009] The soluble metal salt used for doping modification includes at least one of gallium salt, indium salt, cerium salt, manganese salt, cobalt salt, magnesium salt, iron salt, nickel salt, or zirconium salt.

[0010] The specific preparation method includes the following steps:

[0011] Soluble copper salt, soluble zinc salt, soluble metal salt for doping modification, and precipitant are dissolved in ultrapure water, and then subjected to isothermal aging, centrifugation, washing, drying, grinding, calcination, and reduction to obtain the doped metal modified copper-based catalyst.

[0012] Optionally, the soluble metal salt used for doping modification is a gallium salt.

[0013] Optionally, the gallium salt, indium salt, cerium salt, manganese salt, cobalt salt, magnesium salt, iron salt, nickel salt, or zirconium salt may be any one of nitrate, sulfate, or chloride.

[0014] Optionally, the molar ratio of metal ions in the soluble copper salt, soluble zinc salt, and soluble metal salt used for doping modification is Cu∶Zn∶X=2∶3∶(1-5), where X represents the metal ions in the doped and modified soluble metal salt.

[0015] Optionally, the precipitant is one or more combinations of lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate, lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide.

[0016] Optionally, the preparation method of the metal-doped modified copper-based catalyst includes the following steps:

[0017] S1. Dissolve soluble copper salt, soluble zinc salt and doped modified soluble metal salt in ultrapure water to form solution A, and dissolve precipitant in ultrapure water to form solution B;

[0018] S2. Add solutions A and B from S1 dropwise into preheated ultrapure water and age at a constant temperature.

[0019] S3. After aging, the catalyst is centrifuged, washed, dried, ground, calcined and reduced in sequence to obtain a copper-based catalyst modified with metal doping.

[0020] Furthermore, in solution A, the ratio of the total amount of metal in the soluble copper salt, soluble zinc salt, and doped modified soluble metal salt to the amount of ultrapure water is 0.01-5 mol: 10-1000 mL;

[0021] In solution B, the ratio of the precipitant to ultrapure water is 0.01-5 mol: 10-1000 mL.

[0022] Furthermore, in step S2, the dropping rate is 0.1-10 mL / min, and the aging time is 3-24 h.

[0023] Furthermore, the drying process described in step S3 is as follows:

[0024] Vacuum drying oven or forced-air drying oven, drying temperature 50-120℃, drying time 8-24h.

[0025] Furthermore, the conditions during the calcination process described in step S3 are as follows:

[0026] Heat to 200-500℃ at a heating rate of 1-10℃ / min, and then calcine at this temperature for 2-5 hours.

[0027] Furthermore, the restoration process in step S3 is as follows:

[0028] Under the condition that the reducing gas is a 5%-30% H2 / Ar mixture or a 5%-30% CO / Ar mixture, the temperature is increased to 150-450℃ at a heating rate of 1-10℃ / min, and then reduced at this temperature for 0.5-5h.

[0029] The second technical solution of this invention:

[0030] A copper-based catalyst modified with a metal doped substrate was prepared by the method described above.

[0031] The third technical solution of this invention:

[0032] Application of the above-mentioned metal-doped modified copper-based catalysts in the field of low-temperature photothermal hydrogen production.

[0033] Compared with the prior art, the present invention has the following advantages and technical effects:

[0034] While ensuring that the CO concentration in the products during the MSR reaction is less than 10 ppm, which meets the requirements for downstream use in the hydrogen fuel cell industry, this invention improves the photosensitivity of the copper-based catalyst by doping it with metal. This achieves the goal of reducing the reaction temperature to suppress CO generation while significantly improving the light gain hydrogen production efficiency of the copper-based catalyst. Attached Figure Description

[0035] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0036] Figure 1 Comparative Example 1: Unmodified Cu2Zn3 catalyst, hydrogen yield comparison at low temperature and high temperature under pure heat (a) and carbon dioxide content and carbon dioxide selectivity comparison at low temperature and high temperature (b).

[0037] Figure 2 The comparison chart (a) shows the hydrogen yield of the unmodified Cu2Zn3 catalyst in Comparative Example 1 and the modified catalysts in Examples 1-3 under photothermal and pure heat conditions, and the comparison chart (b) shows the carbon monoxide content and carbon dioxide selectivity under photothermal conditions.

[0038] Figure 3 The powder diffraction patterns (a) of the unmodified Cu2Zn3 catalyst in Comparative Example 1, the catalysts after calcination but not reduction in Examples 1-3, and the powder diffraction patterns (b) of the reduced catalysts are shown.

[0039] Figure 4 Transient photocurrent curves of the unmodified Cu2Zn3 catalyst in Comparative Example 1 and the modified catalysts in Examples 1-3 are shown.

[0040] Figure 5 The graph shows the hydrogen production performance of the catalysts prepared in Examples 1, 4, and 5 under photothermal and pure thermal conditions (a) and the comparison graph of carbon monoxide content and carbon dioxide selectivity under photothermal conditions (b). Detailed Implementation

[0041] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0042] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0043] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0044] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0045] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0046] This invention discloses a method for preparing a metal-doped modified copper-based catalyst, comprising the following steps:

[0047] S1. Dissolve soluble copper salt, soluble zinc salt and doped modified soluble metal salt in ultrapure water to form solution A, and dissolve precipitant in ultrapure water to form solution B;

[0048] S2. Use a three-necked flask to hold an appropriate amount of ultrapure water, and place the ultrapure water in a heating device for preheating. The amount of ultrapure water used here does not need to be limited.

[0049] S3. Add solutions A and B from S1 to the preheated ultrapure water in S2 at a certain dropping rate. After the addition of solutions A and B is complete, age at a constant temperature.

[0050] S4. After aging, the catalyst is centrifuged, washed, dried, ground, calcined and reduced in sequence to obtain a copper-based catalyst with metal doping.

[0051] In some alternative embodiments, in step S1, the soluble copper salt includes one or more of copper nitrate, copper sulfate, copper chloride, copper acetate, and copper carbonate.

[0052] Soluble zinc salts include one or more of zinc chloride, zinc nitrate, zinc sulfate, zinc acetate, zinc fluorosilicate, zinc fluoroborate, and zinc gluconate;

[0053] The doped and modified soluble metal salts include one or more of gallium salts, indium salts, cerium salts, manganese salts, cobalt salts, magnesium salts, iron salts, nickel salts, or zirconium salts; furthermore, the gallium salts, indium salts, cerium salts, manganese salts, cobalt salts, magnesium salts, iron salts, nickel salts, or zirconium salts may be selected as: gallium chloride, gallium sulfate, gallium nitrate, indium chloride, indium sulfate, indium nitrate, cerium chloride, cerium sulfate, cerium nitrate, manganese chloride, manganese sulfate, manganese nitrate, cobalt chloride, cobalt sulfate, cobalt nitrate, magnesium chloride, magnesium sulfate, magnesium nitrate, ferric chloride, ferric sulfate, ferric nitrate, nickel chloride, nickel sulfate, nickel nitrate, zirconium chloride, zirconium sulfate, and zirconium nitrate.

[0054] In some alternative embodiments, in step S1, the molar ratio of metal atoms in solution A is Cu∶Zn∶X=2∶3∶(1-5), where X represents the metal atoms in the doped and modified soluble metal salt.

[0055] In some optional embodiments, in step S1, the precipitant is one or more of lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate, lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide.

[0056] In some optional embodiments, in step S1, the metal content of the soluble salt is 0.01-5 mol, the amount of ultrapure water used in both solution A and solution B is 10-1000 mL, and the amount of precipitant used is 0.01-5 mol.

[0057] In some alternative embodiments, in step S2, the temperature is preheated to 50-100°C.

[0058] In some alternative embodiments, in step S3, the dropping rate is 0.1-10 mL / min and the aging time is 3-24 h.

[0059] In some optional embodiments, in step S4, the washing process is as follows:

[0060] Solid-liquid separation is performed using a centrifuge with a speed of 3000-11000 rpm.

[0061] In some optional embodiments, in step S4, the drying process is as follows:

[0062] Vacuum drying oven or forced-air drying oven, drying temperature 50-120℃, drying time 8-24h.

[0063] In some optional embodiments, the conditions during the calcination process in step S4 are as follows:

[0064] The calcination temperature is 200-500℃, the calcination time is 2-5h, the heating rate is 1-10℃ / min, and the calcination equipment is a muffle furnace.

[0065] In some optional embodiments, in step S4, the reducing gas used in the reduction process is a 5%-30% H2 / Ar (i.e., H2 volume concentration 5%-30%) mixture or a 5%-30% CO / Ar mixture (i.e., CO volume concentration 5%-30%), the reduction temperature is 150-450℃, the reduction time is 0.5-5h, and the heating rate is 1-10℃ / min.

[0066] This invention discloses a metal-doped modified copper-based catalyst, which is prepared by the above-described preparation method.

[0067] This invention also discloses the application of the above-mentioned metal-doped modified copper-based catalyst in the field of low-temperature photothermal hydrogen production.

[0068] The process of using the above-mentioned metal-doped modified copper-based catalyst for low-temperature photothermal hydrogen production is as follows:

[0069] (1) Place 30-500 mg of doped metal modified copper-based catalyst into a container containing solvent (the solvent is one or more combinations of ultrapure water, methanol, and ethanol, and the amount is 0.5-5 mL), sonicate to disperse it evenly, and then drop it onto a circular glass slide. Use a constant temperature heating table to evaporate and dry the solvent.

[0070] (2) A certain proportion of methanol aqueous solution was added to the photothermal batch reactor (CEL-HPR, purchased from Beijing Zhongjiao Jinyuan Technology Co., Ltd.) to serve as the reaction substrate. The support was placed in the reactor, and the circular glass plate with uniformly attached catalyst in (1) was placed on the support to separate the substrate from the catalyst. At this time, the substrate was located below the support and the catalyst was located above the support.

[0071] (3) After the photothermal intermittent reactor is installed, the atmosphere inside the reactor is replaced with an inert gas, and the pressure inside the reactor is increased to 0-5 MPa with an inert gas (one or more of N2, Xe, Ne, Kr, Ar, He).

[0072] (4) Place the reactor from (3) in a heating jacket and heat it to the required temperature (190-210℃). Irradiate the catalyst using a simulated light source through a light window. The intensity of the simulated light source is 0-3000 mW / cm². 2 After the reaction is complete, cool to room temperature and collect the gaseous products.

[0073] Unless otherwise specified, "room temperature" in this invention refers to 20-30℃.

[0074] All raw materials used in this invention were purchased commercially. The gallium nitrate hydrate used in the following examples was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., with the structural formula Ga(NO3)3·xH2O and a molecular weight of 255.74.

[0075] The technical solution of the present invention will be further illustrated by the following embodiments.

[0076] Example 1

[0077] A method for preparing a Cu2Zn3 catalyst includes the following steps:

[0078] 100 mL of metal precursor solution A (2.3490 g copper nitrate trihydrate, 4.3386 g zinc nitrate hexahydrate, and 1.2432 g gallium nitrate hydrate) and 100 mL of sodium carbonate solution B (3.5 g) were simultaneously added at a rate of 0.8 mL / min to a three-necked flask containing 300 mL of ultrapure water (preheated to 70 °C). The flask was placed in an oil bath at 100 °C with stirring. After the addition was complete, the mixture was aged at this temperature for 20 h. The reaction solution was then centrifuged (at 11,000 rpm) to collect the solid. The solid was washed and dried at 85℃ for 12h, calcined in a muffle furnace at 400℃ for 3h (heating rate 5℃ / min), and then naturally cooled to room temperature. Before catalyst performance testing, it was reduced at 300℃ for 1h (heating rate 5℃ / min) using a 10% H2 / Ar mixed gas and then naturally cooled to room temperature to obtain Cu2Zn3Ga1 catalyst (Cu∶Zn∶Ga=2∶3∶1 in the raw material, abbreviated as catalyst Cu2Zn3Ga1).

[0079] Example 2

[0080] The difference from Example 1 is that gallium nitrate nonahydrate was replaced with an equimolar amount of cobalt nitrate nonahydrate, while the amounts of other raw materials and the preparation process were the same as in Example 1. The resulting catalyst was Cu2Zn3Co1.

[0081] Example 3

[0082] The difference from Example 1 is that gallium nitrate nonahydrate was replaced with an equimolar amount of cerium nitrate hexahydrate, while the amounts of other raw materials and the preparation process were the same as in Example 1. The resulting catalyst was Cu₂Zn₃Ce₁.

[0083] Example 4

[0084] The difference from Example 1 is that,

[0085] Solution A consisted of 2.0134 g copper nitrate trihydrate, 3.7188 g zinc nitrate hexahydrate, and 2.1313 g gallium nitrate hydrate. Other quantities and preparation procedures were the same as in Example 1. The final catalyst obtained was Cu₂Zn₃Ga₂.

[0086] Example 5

[0087] The difference from Example 1 is that,

[0088] Solution A consisted of 1.4094 g copper nitrate trihydrate, 2.6032 g zinc nitrate hexahydrate, and 3.7297 g gallium nitrate hydrate. Other quantities and preparation procedures were the same as in Example 1. The final catalyst obtained was Cu₂Zn₃Ga₅.

[0089] Comparative Example 1

[0090] The difference from Example 1 is that gallium nitrate hydrate is not added, but the amount of other raw materials and the preparation process are the same as in Example 1, and the catalyst obtained is Cu2Zn3.

[0091] Comparative Example 2 (see CN 118359168 A)

[0092] The preparation process of CuZnAl catalyst is as follows:

[0093] a. Weigh 1.694g of Cu(NO3)2·3H2O, 1.188g of Zn(NO3)2·6H2O, and 0.375g of Al(NO3)3·9H2O (the molar ratio of Cu:Zn:Al = 7:4:1) and add them to a 50mL beaker. Add 20mL of deionized water to dissolve them and stir vigorously at 65℃ for 20min to prepare a salt solution.

[0094] b. Weigh 2.12g of Na2CO3, dissolve it in 20mL of deionized water, and prepare a precipitant solution;

[0095] c. Place the salt solution from step a in a 50°C water bath, add the precipitant solution from step b dropwise to the salt solution, stir vigorously, and stop the reaction when the pH value reaches 8. Then raise the temperature to 70°C and continue stirring at this temperature to age the precipitate for 120 min. The obtained precipitate is filtered, washed, and then dried in a forced-air drying oven at 80°C for 12 h to obtain the CuZnAl catalyst.

[0096] The aluminum-doped modified CuZnAl catalyst prepared in Comparative Example 2 exhibits a light power of 500 mW / cm² at a low temperature of 190 °C. 2 At that time, the hydrogen production rate (tens of mmol·g) cat -1 ·h -1 The hydrogen generation rate of the catalysts modified with gallium, cerium, and cobalt metals prepared in Examples 1-3 of this invention is far lower than that of the catalysts (37-53 mmol·g). cat -1 ·h -1 This demonstrates that the modified catalyst prepared by the doped metal species selected in this invention can significantly improve the hydrogen generation rate under low temperature and low light power conditions, while also ensuring the suppression of CO generation.

[0097] Effect verification

[0098] Example 1

[0099] 30 mg of the catalyst prepared in Comparative Example 1 was dispersed in 1 mL of methanol and sonicated for 10 min. The catalyst was then evenly coated onto a circular glass slide using a dropper and dried on a constant temperature heating platform at 70 °C. 40 mL of a 1:1 (molar ratio) methanol-water mixture was poured into a photothermal intermittent reactor. After placing the catalyst-coated circular glass slide into the reactor and completing the assembly, the air inside the reactor was replaced with nitrogen. The pressure inside the reactor was increased to 2 MPa, and the reactor was placed on a heating mantle and heated to 190 °C or 210 °C. After reacting for 75 min, the hydrogen content, CO content, and CO2 selectivity of Cu2Zn3 under thermocatalytic reaction (TC) conditions were measured.

[0100] Figure 1 Comparative Example 1: Unmodified Cu₂Zn₃ catalyst, hydrogen yield comparison (a) at low temperature and high temperature under pure heat, and carbon dioxide content and carbon dioxide selectivity comparison (b) at low temperature and high temperature. From... Figure 1 As can be seen from the results, the unmodified copper-based catalyst in Comparative Example 1 can increase the hydrogen reaction rate under high temperature conditions, but it will intensify the reverse water gas reaction, resulting in a significant increase in CO content. While cooling can reduce CO content, the hydrogen production efficiency is low. Therefore, it is necessary to modify the catalyst to obtain better low-temperature hydrogen production performance.

[0101] Example 2

[0102] 30 mg of catalyst (the catalysts prepared in Comparative Example 1 and Examples 1-3) was dispersed in 1 mL of methanol and sonicated for 10 min. The solution was then evenly drop-coated onto a circular glass slide using a dropper and dried on a constant-temperature heating platform at 70 °C. 40 mL of a 1:1 (molar ratio) methanol-water mixture was poured into a photothermal intermittent reactor. The catalyst-coated circular glass slide was then placed into the reactor. After purging the reactor with nitrogen, the pressure was increased to 2 MPa. The reactor was then placed on a heating mantle and heated to 190 °C. The intensity of the simulated light source was adjusted to 500 mW / cm². 2 The reaction vessel undergoes a photothermal reaction (PTC) after being irradiated through a light window; a purely thermal reaction (TC) can be carried out by turning off the simulated light source during the reaction. The reaction time for both reactions is 75 minutes. After the reaction, the reaction vessel is cooled to room temperature and the gas is collected. The contents of hydrogen, carbon monoxide, and carbon dioxide are detected by gas chromatography.

[0103] Figure 2 The graph (a) shows a comparison of hydrogen yield under photothermal and pure heat conditions between the unmodified Cu2Zn3 catalyst in Comparative Example 1 and the modified catalysts in Examples 1-3, and (b) shows a comparison of carbon monoxide content and carbon dioxide selectivity under photothermal conditions. Figure 2As can be seen from Figure a, the hydrogen yield under TC conditions was slightly increased after modification with gallium, cerium, and cobalt metals, while the hydrogen yield under PTC conditions was significantly increased, reaching 52.71, 40.97, and 37.17 mmol·g, respectively. cat -1 ·h -1 ;from Figure 2 As can be seen from Figure b, the CO2 selectivity of the catalysts modified with gallium, cerium, and cobalt metals is improved under PTC reaction conditions, and the CO content is lower than that of Comparative Example 1 and <10ppm, which meets the requirements of the downstream hydrogen fuel cell industry.

[0104] Figure 3 The images show the powder diffraction patterns (a) of the unmodified Cu₂Zn₃ catalyst in Comparative Example 1, the calcined but unreduced catalysts in Examples 1-3, and the powder diffraction pattern (b) of the reduced catalysts. Figure 3 As can be seen, gallium forms a solid solution with copper, which improves the dispersion of copper; cerium is doped in the form of oxide, which acts as an auxiliary agent to change the pH of the catalyst and thus improve the catalytic efficiency; cobalt exists as elemental cobalt after reduction, which provides additional active sites for the catalyst.

[0105] Figure 4 The transient photocurrent curves are shown for the unmodified Cu2Zn3 catalyst in Comparative Example 1 and the modified catalysts in Examples 1-3. From... Figure 4 As can be seen from the results, the modified catalysts in Examples 1-3 of this invention have higher photosensitivity.

[0106] In summary, the metal doping strategy of this invention can significantly improve the photosensitivity of copper-based catalysts, enhance their low-temperature hydrogen production activity, and increase their carbon dioxide selectivity by increasing the dispersion of copper, altering the acidity or basicity of the catalyst, or providing additional active sites.

[0107] Example 3

[0108] 30 mg of catalyst (catalysts prepared in Examples 1, 4, and 5) was dispersed in 1 mL of methanol and sonicated for 10 min. The solution was then evenly drop-coated onto a circular glass slide using a dropper and dried on a constant-temperature heating platform at 70°C. 40 mL of a 1:1 (molar ratio) methanol-water mixture was poured into a photothermal intermittent reactor. The catalyst-coated circular glass slide was then placed into the reactor. After purging the reactor with nitrogen, the pressure was increased to 2 MPa. The reactor was then placed on a heating mantle and heated to 190°C. The intensity of the simulated light source was adjusted to 500 mW / cm². 2 The reaction vessel undergoes a photothermal reaction (PTC) after being irradiated through a light window; a purely thermal reaction (TC) can be carried out by turning off the simulated light source during the reaction. The reaction time for both reactions is 75 minutes. After the reaction is completed, the reaction vessel is cooled to room temperature and the gas is collected. Hydrogen gas is then detected using gas chromatography.

[0109] Figure 5 The figures (a) show the hydrogen production performance of the catalysts prepared in Examples 1, 4, and 5 under photothermal and pure heat conditions, and (b) show the comparison of carbon monoxide content and carbon dioxide selectivity under photothermal conditions. As can be seen from the figures, within the range of metal ion ratios defined in this invention, changing the proportion of Ga does not change the hydrogen production activity and carbon dioxide selectivity of the prepared catalysts.

[0110] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. Use of a metal-doped modified copper-based catalyst in low-temperature photo-thermal hydrogen production, characterized in that, The copper-based catalyst doped with metal is prepared by the following steps: dissolving soluble copper salt, soluble zinc salt, and soluble metal salt for doping modification into water to form solution A, dissolving a precipitant into water to form solution B, adding solution A and solution B into preheated water, and aging at constant temperature. The soluble metal salt for doping modification is at least one of gallium salt or cerium salt. The molar ratio of metal ions in the soluble copper salt, the soluble zinc salt, and the soluble metal salt for doping modification is 2:3:(1-5).

2. Use of the doped metal-modified copper-based catalyst according to claim 1 in low-temperature photo-thermal hydrogen production, characterized in that, The gallium salt and the cerium salt are any one of nitrate, sulfate, or chloride.

3. Use of the doped metal-modified copper-based catalyst according to claim 1 in low-temperature photo-thermal hydrogen production, characterized in that, The precipitant is one or more of lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate, lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide.

4. Use of the doped metal-modified copper-based catalyst according to claim 1 in low-temperature photo-thermal hydrogen production, characterized in that, The drying process is drying at 50-120℃ for 8-24h; and / or, The conditions in the calcination process are: increasing the temperature to 200-500℃ at a temperature increasing rate of 1-10℃ / min, then calcining at the temperature for 2-5h, and then cooling to room temperature; and / or, The reduction process is: increasing the temperature to 150-450℃ at a temperature increasing rate of 1-10℃ / min under the condition that the reducing gas is 5%-30% H2 / Ar mixed gas or 5%-30% CO / Ar mixed gas, then reducing at the temperature for 0.5-5h, and then cooling to room temperature.

5. Use of the doped metal-modified copper-based catalyst according to claim 1 in low-temperature photo-thermal hydrogen production, characterized in that, The preparation method of the copper-based catalyst doped with metal includes the following steps: S1, dissolving soluble copper salt, soluble zinc salt, and soluble metal salt for doping modification into ultrapure water to form solution A, and dissolving a precipitant into ultrapure water to form solution B; S2, adding solution A and solution B in S1 into preheated ultrapure water, and aging at constant temperature; S3, after aging, sequentially performing centrifugation, washing, drying, grinding, calcination, and reduction to prepare the copper-based catalyst doped with metal.

6. Use of the doped metal-modified copper-based catalyst according to claim 5 for low-temperature photo-thermal hydrogen production, characterized in that, The temperature for aging at constant temperature is 100℃, and the time is 20h.

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