Metal-doped modified copper-based catalyst as well as preparation method and application thereof

Abstract

The invention discloses a metal-doped modified copper-based catalyst as well as a preparation method and application thereof, and belongs to the technical field of chemical hydrogen production. A preparation method of a metal-doped modified copper-based catalyst comprises the following steps: dissolving soluble copper salt, soluble zinc salt, soluble metal salt for doping modification and a precipitator in ultrapure water, and then performing constant-temperature aging, centrifugation, washing, drying, grinding, calcination and reduction to prepare the metal-doped modified copper-based catalyst, wherein the soluble metal salt for doping modification comprises at least one of gallium salt, indium salt, cerium salt, manganese salt, cobalt salt, magnesium salt, ferric salt, nickel salt or zircon salt. By doping the metal modified copper-based catalyst, the photosensitivity of the copper-based catalyst is improved, and the optical gain hydrogen production efficiency of the copper-based catalyst is remarkably improved while the reaction temperature is reduced and CO generation is inhibited; and the CO concentration in the product during the MSR reaction is less than 10ppm, so that the downstream use of the hydrogen fuel cell industry is met.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical hydrogen production, and in particular relates to a doped metal-modified copper-based catalyst and a preparation method and application thereof. Background Art

[0002] Among many clean energy sources (solar energy, wind energy, biomass energy, hydropower, geothermal energy, hydrogen energy, etc.), H 2 Due to its ultra-high energy density and zero pollution, as well as its potential to be used in the downstream of the hydrogen fuel cell industry (passenger cars, generators, etc.), it is considered to be the most promising energy source to replace traditional fossil fuels. However, a key problem in hydrogen fuel cells is that the battery electrodes are easily poisoned by CO. The CO content in the hydrogen gas flow must be less than 10ppm, otherwise the catalytic performance of the fuel cell will drop sharply, so the hydrogen concentration requirement is very strict.

[0003] In addition, the highly flammable and explosive nature of hydrogen is very unfavorable for its storage and transportation, which hinders the large-scale use of hydrogen fuel cells. Since liquid fuels are more convenient to store and transport and have a higher hydrogen-to-carbon ratio, hydrogen production through steam reforming of alcohols (methanol, ethanol, propanol, etc.) is expected to become a mobile source of hydrogen. And methanol has a high hydrogen content (12.5%) and a low reforming reaction temperature. The hydrogen production method based on methanol steam reforming (MSR) has been used for commercial hydrogen production. However, the current commercial use of Cu / ZnO / Al 2 O 3 The active temperature range of copper-based catalysts represented by is at a relatively high temperature (220-280°C). In industrial MSR hydrogen production, in order to obtain higher economic benefits, the reaction temperature is usually higher than 250°C to increase the hydrogen yield. In this temperature range, the side reaction (reverse water gas reaction) will be aggravated, resulting in an increase in CO content, which will cause CO 2 The decrease in selectivity is not conducive to the downstream use of hydrogen fuel cell industry.

[0004] Although lowering the reaction temperature can inhibit the formation of CO, the hydrogen yield will be greatly reduced. Introducing light energy into the thermal catalytic reaction can trigger the copper plasmon effect and thus enhance the catalyst activity. While improving the hydrogen production efficiency, it can also lower the reaction temperature, thereby inhibiting the occurrence of the reverse water gas reaction, thereby reducing the CO content and increasing the CO 2 However, traditional copper-based catalysts have a series of problems such as poor photosensitivity, insignificant light gain effect, and low hydrogen production efficiency. Summary of the invention

[0005] In view of the above technical problems, the present invention proposes a doped metal-modified copper-based catalyst and a preparation method and application thereof.

[0006] To achieve the above object, the present invention provides the following technical solutions:

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

[0008] A method for preparing a doped metal-modified copper-based catalyst, using a soluble copper salt, a soluble zinc salt, and a soluble metal salt for doping and modification as precursors, and adopting a coprecipitation method to prepare the doped metal-modified copper-based catalyst;

[0009] Wherein, 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 comprises the following steps:

[0011] The soluble copper salt, the soluble zinc salt, the soluble metal salt for doping and modification and the precipitant are dissolved in ultrapure water, and then are subjected to constant temperature 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 is any one of nitrate, sulfate or chloride.

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

[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 doped metal-modified copper-based catalyst comprises the following steps:

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

[0018] S2, adding solution A and solution B in S1 dropwise into preheated ultrapure water for constant temperature aging;

[0019] S3. After aging, centrifugation, washing, drying, grinding, calcination and reduction are performed in sequence to obtain a doped metal-modified copper-based catalyst.

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

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

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

[0023] Further, the drying process in step S3 is:

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

[0025] Further, the conditions during the calcination process in step S3 are:

[0026] The temperature is raised to 200-500°C at a heating rate of 1-10°C / min, and then calcined at this temperature for 2-5 hours.

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

[0028] In the reducing gas of 5%-30% H 2 Under the conditions of 5%-20% CO / Ar mixed gas or 5%-30% CO / Ar mixed gas, the temperature is increased to 150-450°C at a heating rate of 1-10°C / min, and then reduced at this temperature for 0.5-5h.

[0029] The second technical solution of the present invention:

[0030] A doped metal-modified copper-based catalyst is prepared by the above preparation method.

[0031] The third technical solution of the present invention:

[0032] The application of the above-mentioned doped metal-modified copper-based catalyst 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] Under the condition that the CO concentration in the product during the MSR reaction is less than 10 ppm and meets the use of the downstream hydrogen fuel cell industry, the present invention improves the photosensitivity of the copper-based catalyst by doping metal-modified copper-based catalysts, thereby reducing the reaction temperature to inhibit CO generation and significantly improving the photo-gain hydrogen production efficiency of the copper-based catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0036] Figure 1 Comparative Example 1: Unmodified Cu 2 Zn 3 Comparison of hydrogen yield of catalyst under low temperature and high temperature pure heat (a) and comparison of carbon monoxide content and carbon dioxide selectivity under low temperature and high temperature (b);

[0037] Figure 2 Comparative Example 1: Unmodified Cu 2 Zn 3 Comparison of hydrogen yields of the catalyst and the modified catalyst of Examples 1-3 under photothermal and pure thermal conditions (a) and comparison of carbon monoxide content and carbon dioxide selectivity under photothermal conditions (b);

[0038] Figure 3 Comparative Example 1: Unmodified Cu 2 Zn 3 The catalyst, the catalyst powder diffraction pattern (a) after calcination but not reduced according to Examples 1-3, and the catalyst powder diffraction pattern (b) after reduction;

[0039] Figure 4 Comparative Example 1: Unmodified Cu 2 Zn 3 Transient photocurrent curves of the catalyst and the modified catalyst of Examples 1-3;

[0040] Figure 5 The hydrogen production performance diagram (a) of the catalysts prepared in Examples 1, 4, and 5 under photothermal and pure heat conditions and the comparison diagram (b) of the carbon monoxide content and carbon dioxide selectivity under photothermal conditions. DETAILED DESCRIPTION

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

[0042] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0043] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0044] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

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

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

[0047] S1, dissolving a soluble copper salt, a soluble zinc salt and a doped and modified soluble metal salt in ultrapure water to form a solution A, and dissolving a precipitant in ultrapure water to form a 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, adding solution A and solution B in S1 to the preheated ultrapure water in S2 at a certain drop rate, and after the addition of solution A and solution B is completed, aging at a constant temperature;

[0050] S4, after aging, centrifuging, washing, drying, grinding, calcining and reducing are performed in sequence to obtain a doped metal-modified copper-based catalyst;

[0051] In some optional 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] The soluble zinc salt includes 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 salt includes one or more of gallium salts, indium salts, cerium salts, manganese salts, cobalt salts, magnesium salts, iron salts, nickel salts or zirconium salts; further, the gallium salts, indium salts, cerium salts, manganese salts, cobalt salts, magnesium salts, iron salts, nickel salts or zirconium salts can be selected from: 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, iron chloride, iron sulfate, iron nitrate, nickel chloride, nickel sulfate, nickel nitrate, zirconium chloride, zirconium sulfate, zirconium nitrate or one or more.

[0054] In some optional embodiments, in step S1, the molar ratio of the metal atoms in solution A is Cu:Zn:X=2:3:(1-5), wherein X represents the metal atom in the doped 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 solution A and solution B is 10-1000 mL, and the amount of the precipitant used is 0.01-5 mol.

[0057] In some optional embodiments, in step S2, preheating is performed to 50-100°C.

[0058] In some optional embodiments, in step S3, the dripping 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:

[0060] Solid-liquid separation is performed by centrifuge, and the centrifuge speed is 3000-11000rpm.

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

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

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

[0064] The calcination temperature is 200-500°C, the calcination time is 2-5h, the heating rate is 1-10°C / 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 5%-30% H 2 / Ar(i.e. H 2 The reduction temperature is 150-450°C, the reduction time is 0.5-5h, and the heating rate is 1-10°C / min.

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

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

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

[0069] (1) 30-500 mg of the doped metal-modified copper-based catalyst is placed in a container containing a solvent (the solvent is one or more combinations of ultrapure water, methanol, and ethanol, with an amount of 0.5-5 mL), and ultrasonically dispersed, and then dropped onto a round glass sheet, and the solvent is evaporated and dried using a constant temperature heating table;

[0070] (2) A certain proportion of methanol aqueous solution was added to a photothermal intermittent reactor (CEL-HPR, purchased from Beijing Zhongjiao Jinyuan Technology Co., Ltd.) as a reaction substrate, and a support was placed. The round glass piece with the catalyst uniformly attached 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 batch reactor is installed, the atmosphere in the reactor is replaced with an inert gas and the inert gas (N 2 , one or more combinations of Xe, Ne, Kr, Ar, and He) to charge the pressure of the reactor to 0-5Mpa;

[0072] (4) Place the reactor in (3) in a heating jacket and heat to the desired temperature (190-210°C). Use a simulated light source to illuminate the catalyst through the light window. The simulated light source intensity is 0-3000 mW / cm 2 After the reaction is completed, the mixture is cooled to room temperature and the gaseous product is collected.

[0073] The "room temperature" in the present invention refers to 20-30°C unless otherwise specified.

[0074] The raw materials used in the present invention are all purchased from the market. The gallium nitrate hydrate used in the following examples was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., and its structural formula is Ga(NO 3 )3 ·xH 2 O, molecular weight is 255.74.

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

[0076] Example 1

[0077] A Cu 2 Zn 3 The method for preparing a catalyst comprises the following steps:

[0078] 100 mL of metal precursor solution A (2.3490 g of copper nitrate trihydrate, 4.3386 g of zinc nitrate hexahydrate, and 1.2432 g of gallium nitrate hydrate) and 100 mL of sodium carbonate (3.5 g) solution B were added simultaneously at a rate of 0.8 mL / min into a three-necked flask containing 300 mL of ultrapure water (preheated to 70°C), and stirred in an oil bath at 100°C. After the addition was completed, the mixture was aged at a constant temperature for 20 h, and the reaction solution was centrifuged (at a speed of 11000 rpm) to collect the solid and wash it. The obtained solid was dried at 85°C for 12 h, calcined in a muffle furnace at 400°C for 3 h (heating rate of 5°C / min), and naturally cooled to room temperature. 10% H 2 / Ar mixed gas was reduced at 300℃ for 1h (heating rate was 5℃ / min), and then naturally cooled to room temperature to obtain Cu 2 Zn 3 Ga 1 Catalyst (Cu:Zn:Ga=2:3:1 in raw materials, referred to as Cu 2 Zn 3 Ga 1 ).

[0079] Example 2

[0080] The difference from Example 1 is that gallium nitrate nonahydrate is replaced by an equal mole of cobalt nitrate nonahydrate, and the other raw material amounts and preparation process are the same as in Example 1. The obtained catalyst is Cu 2 Zn 3 Co 1 .

[0081] Example 3

[0082] The difference from Example 1 is that gallium nitrate nonahydrate is replaced by cerium nitrate hexahydrate in an equal mole, and the other raw material amounts and preparation process are the same as in Example 1. The obtained catalyst is Cu 2 Zn 3 Ce 1 .

[0083] Example 4

[0084] The difference from Example 1 is that

[0085] Solution A contains 2.0134 g of copper nitrate trihydrate, 3.7188 g of zinc nitrate hexahydrate, and 2.1313 g of gallium nitrate hydrate. Other amounts and preparation processes are the same as in Example 1. The catalyst finally obtained is Cu 2 Zn 3 Ga 2 .

[0086] Example 5

[0087] The difference from Example 1 is that

[0088] Solution A contains 1.4094 g of copper nitrate trihydrate, 2.6032 g of zinc nitrate hexahydrate, and 3.7297 g of gallium nitrate hydrate. Other amounts and preparation processes are the same as in Example 1. The catalyst finally obtained is Cu 2 Zn 3 Ga 5 .

[0089] Comparative Example 1

[0090] The difference from Example 1 is that gallium nitrate hydrate is not added, the amounts of other raw materials and the preparation process are the same as in Example 1, and the obtained catalyst is Cu 2 Zn 3 .

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

[0092] The preparation process of CuZnA1 catalyst is as follows:

[0093] a. Weigh 1.694 g of Cu(NO 3 ) 2 ·3H 2 O, 1.188 g Zn(NO 3 ) 2 6H 2 O, 0.375 g of A1(NO 3 ) 3 9H 2 O (Cu: Zn: Al molar ratio = 7: 4: 1) was added to a 50 mL beaker, dissolved in 20 mL of deionized water, and stirred vigorously at 65 °C for 20 min to prepare a salt solution;

[0094] b. Weigh 2.12g of Na 2 CO 3 , dissolved in 20 mL of deionized water to prepare a precipitant solution;

[0095] c. The salt solution in step a is placed in a 50°C water bath, and the precipitant solution in step b is added dropwise to the salt solution, and stirred vigorously. The pH value is controlled to terminate at 8 when the reaction is terminated, and then the temperature is raised to 70°C. At this temperature, the precipitate is aged for 120 minutes with continuous stirring. The obtained precipitate is filtered and washed, and then dried in a forced air drying oven at 80°C for 12 hours to obtain a CuZnA1 catalyst.

[0096] The aluminum-doped modified CuZnA1 catalyst prepared in Comparative Example 2 was heated to 190°C at a light power of 500 mW / cm 2 When the hydrogen generation rate (more than ten mmol·g cat -1 ·h -1 ) is much lower than the hydrogen generation rate (37-53 mmol·g) of the catalysts modified with gallium, cerium and cobalt prepared in Examples 1-3 of the present invention. cat -1 ·h -1 ), which proves that the modified catalyst prepared by the doped metal species selected in the present invention can significantly increase the hydrogen generation rate under low temperature and low light power conditions, and can also ensure the inhibition of CO generation.

[0097] Effect verification

[0098] Effect Example 1

[0099] 30 mg of the catalyst prepared in Comparative Example 1 was dispersed in 1 mL of methanol, ultrasonicated for 10 min, and evenly applied on a round glass sheet using a dropper, placed on a constant temperature heating table at 70 ° C for drying, 40 mL of a mixed solution of methanol and water in a ratio of 1:1 (molar ratio) was taken and poured into a photothermal intermittent reactor, and the round glass sheet coated with the catalyst was placed in the reactor, after which it was installed, the air in the reactor was replaced with nitrogen, and the pressure of the reactor was filled to 2 MPa, and the reactor was placed on a heating jacket and heated to 190 ° C or 210 ° C. After the reaction for 75 min, the Cu under the conditions of thermal catalytic reaction (TC) was measured. 2 Zn 3 The hydrogen content, CO content and CO 2 Selective.

[0100] Figure 1 Comparative Example 1: Unmodified Cu 2 Zn 3 Comparison of hydrogen yield of catalyst under low temperature and high temperature pure heat (a) and comparison of carbon monoxide content and carbon dioxide selectivity under low temperature and high temperature (b). Figure 1It can be seen that the unmodified copper-based catalyst in comparative example 1 can increase the hydrogen reaction rate when reacting under high temperature conditions, but it will aggravate the reverse water gas reaction and greatly increase the CO content. Although cooling can reduce the CO content, the hydrogen production efficiency is low. Therefore, it needs to be modified to obtain better low-temperature hydrogen production performance.

[0101] Effect Example 2

[0102] 30 mg of catalyst (catalyst prepared in Comparative Example 1 and Examples 1-3) was dispersed in 1 mL of methanol, and ultrasonicated for 10 min. The catalyst was evenly applied on a round glass sheet using a dropper and placed on a constant temperature heating table at 70°C for drying. 40 mL of a mixed solution of methanol and water in a ratio of 1:1 (molar ratio) was poured into a photothermal intermittent reactor. The round glass sheet coated with the catalyst was placed in the reactor and installed. After replacing the air in the reactor with nitrogen, the pressure of the reactor was filled to 2 MPa, and the reactor was placed on a heating jacket and heated to 190°C. The intensity of the simulated light source was adjusted to 500 mW / cm 2 , after irradiation with the light window, a photothermal reaction (PTC) is carried out; when the simulated light source is turned off during the reaction, a pure thermal reaction (TC) can be carried out. The above reaction time is 75 minutes. After the reaction is completed, the reactor is cooled to room temperature and the gas is collected. The content of hydrogen, carbon monoxide and carbon dioxide is detected by gas chromatography.

[0103] Figure 2 Comparative Example 1: Unmodified Cu 2 Zn 3 Comparison of hydrogen yield of the catalyst and the modified catalyst of Examples 1-3 under photothermal and pure thermal conditions (a) and comparison of carbon monoxide content and carbon dioxide selectivity under photothermal conditions (b). Figure 2 As can be seen in a, the hydrogen yields under TC conditions increased slightly after modification with gallium, cerium, and cobalt metals, while the hydrogen yields under PTC conditions increased significantly, reaching 52.71, 40.97, and 37.17 mmol·g, respectively. cat -1 ·h -1 ;from Figure 2 As can be seen in b, the catalysts modified by gallium, cerium, and cobalt metals can react with CO under PTC reaction conditions. 2 The selectivity is improved, and the CO content is lower than that of comparative example 1, and is <10ppm, meeting the downstream requirements of the hydrogen fuel cell industry.

[0104] Figure 3 Comparative Example 1: Unmodified Cu 2 Zn 3 The catalyst, the catalyst powder diffraction pattern (a) after calcination but not reduced in Example 1-3, and the catalyst powder diffraction pattern (b) after reduction. Figure 3It can be seen that gallium and copper form a solid solution to improve the dispersion of copper; cerium is doped in the form of oxide, which acts as an additive to change the pH of the catalyst and thus improve the catalytic efficiency; cobalt exists in the form of elemental cobalt after reduction, providing additional active sites for the catalyst.

[0105] Figure 4 Comparative Example 1: Unmodified Cu 2 Zn 3 The transient photocurrent curves of the catalyst and the modified catalyst of Examples 1-3. Figure 4 It can be seen that the modified catalysts of Examples 1-3 of the present invention have higher photosensitivity.

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

[0107] Effect Example 3

[0108] 30 mg of catalyst (the catalyst prepared in Examples 1, 4, and 5) was dispersed in 1 mL of methanol, and ultrasonicated for 10 min. The catalyst was evenly applied on a round glass sheet using a dropper and placed on a constant temperature heating table at 70°C for drying. 40 mL of a mixed solution of methanol and water in a ratio of 1:1 (molar ratio) was poured into a photothermal intermittent reactor. The round glass sheet coated with the catalyst was placed in the reactor and installed. After replacing the air in the reactor with nitrogen, the pressure of the reactor was filled to 2 MPa, and the reactor was placed on a heating jacket and heated to 190°C. The intensity of the simulated light source was adjusted to 500 mW / cm 2 , after irradiation with the light window, a photothermal reaction (PTC) is carried out; during the reaction, the simulated light source is turned off to carry out a pure thermal reaction (TC). The above reaction time is 75 minutes. After the reaction is completed, the reactor is cooled to room temperature to collect the gas, and the hydrogen is detected by gas chromatography.

[0109] Figure 5 The hydrogen production performance diagram (a) of the catalysts prepared in Examples 1, 4 and 5 under photothermal and pure heat conditions and the comparison diagram (b) of carbon monoxide content and carbon dioxide selectivity under photothermal conditions. It can be seen from the figures that within the ratio range of metal ions specified in the present invention, by changing the proportion of Ga, the prepared catalyst still has excellent hydrogen production activity and carbon dioxide selectivity.

[0110] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing a doped metal-modified copper-based catalyst, characterized in that: The doped metal-modified copper-based catalyst is prepared by a coprecipitation method using a soluble copper salt, a soluble zinc salt and a soluble metal salt for doping and modification as precursors; Wherein, the soluble metal salt used for doping modification is selected from at least one of gallium salt, indium salt, cerium salt, manganese salt, cobalt salt, magnesium salt, iron salt, nickel salt or zirconium salt.

2. The method for preparing a doped metal-modified copper-based catalyst according to claim 1, characterized in that: The following steps are involved: The soluble copper salt, the soluble zinc salt, the soluble metal salt for doping and modification and the precipitant are dissolved in water, and then the catalyst is subjected to constant temperature aging, centrifugation, washing, drying, grinding, calcination and reduction to obtain the doped metal modified copper-based catalyst.

3. The method for preparing a doped metal-modified copper-based catalyst according to claim 1, characterized in that: The gallium salt, indium salt, cerium salt, manganese salt, cobalt salt, magnesium salt, iron salt, nickel salt or zirconium salt is any one of nitrate, sulfate or chloride.

4. The method for preparing a doped metal-modified copper-based catalyst according to claim 1, characterized in that: The molar ratio of metal ions in the soluble copper salt, the soluble zinc salt and the soluble metal salt used for doping and modification is 2:3:(1-5).

5. The method for preparing a doped metal-modified copper-based catalyst according to claim 2, characterized in that: The precipitating agent is selected from 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.

6. The method for preparing a doped metal-modified copper-based catalyst according to claim 2, characterized in that: The drying process is: drying at 50-120° C. for 8-24 hours; and / or, The conditions during the calcination process are: heating to 200-500°C at a heating rate of 1-10°C / min, then calcining at this temperature for 2-5h, and then cooling to room temperature; and / or, The reduction process is as follows: under the condition that the reducing gas is a 5%-30% H2 / Ar mixed gas or a 5%-30% CO / Ar mixed gas, the temperature is raised to 150-450°C at a heating rate of 1-10°C / min, then reduced at this temperature for 0.5-5h, and then cooled to room temperature.

7. The method for preparing a doped metal-modified copper-based catalyst according to claim 1, characterized in that: The preparation method of the doped metal-modified copper-based catalyst comprises the following steps: S1, dissolving a soluble copper salt, a soluble zinc salt and a doped and modified soluble metal salt in ultrapure water to form a solution A, and dissolving a precipitant in ultrapure water to form a solution B; S2, adding solution A and solution B in S1 dropwise into preheated ultrapure water for constant temperature aging; S3. After aging, centrifugation, washing, drying, grinding, calcination and reduction are performed in sequence to obtain a doped metal-modified copper-based catalyst.

8. The method for preparing a doped metal-modified copper-based catalyst according to claim 7, characterized in that: The temperature of the constant temperature aging is 100° C. and the time is 20 hours.

9. A doped metal-modified copper-based catalyst, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the metal-doped copper-based catalyst modified as claimed in claim 9 in the field of low-temperature photothermal hydrogen production.

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