Copper-nickel diatom modified indium-based catalyst, preparation method thereof and method for preparing methanol by catalyzing oxidation of coal bed gas

Abstract

The invention provides a copper-nickel diatom modified indium-based catalyst and a preparation method thereof, and a method for catalyzing coal bed gas oxidation to prepare methanol. The catalyst is a copper-nickel diatom site loaded indium oxide nanotube, a carrier of the catalyst is the indium oxide nanotube, and an active source is a copper-nickel diatom site constructed by a specific photodeposition sequence. According to the method, methane in the coal bed gas can be converted into methanol, compared with the prior art, the methanol yield is higher, effective utilization of clean energy can be achieved, and the method has good application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, and particularly relates to an indium-based catalyst modified with copper-nickel dual atoms, a preparation method thereof, and an application thereof in the catalytic oxidation of coalbed methane to methanol. Background Art

[0002] Among many small molecule liquid products, methanol can be directly obtained by inserting an oxygen atom into a methane molecule, which is extremely efficient from the perspective of atom economy. Moreover, methanol is an important clean fuel and chemical raw material, and is an intermediate carrier connecting traditional fossil energy and renewable energy. Realizing the direct partial oxidation of coalbed methane to methanol will significantly reduce the overall energy consumption of the high-value utilization of coalbed methane, obtain higher economic benefits and environmental protection impetus while improving energy utilization efficiency, and contribute to promoting the adjustment of China's energy structure. At present, the most active catalyst in the reaction of preparing methanol from coalbed methane is a noble metal catalyst. However, due to the high price of noble metal catalysts, their industrial application prospects are limited. Therefore, seeking non-noble metal catalysts with high efficiency in converting coalbed methane and high methanol yield is a hot spot and difficulty in the research of catalytic conversion of coalbed methane. Summary of the Invention

[0003] In view of the above problems, the present invention proposes a preparation method of an indium-based catalyst modified with copper-nickel dual atoms, which has excellent catalytic activity, especially in the catalytic oxidation of coalbed methane to methanol, and has good practical prospects.

[0004] One object of the present invention is to provide a preparation method of an indium-based catalyst modified with copper-nickel dual atoms.

[0005] Another object of the present invention is to provide an indium-based catalyst modified with copper-nickel dual atoms prepared by the above preparation method.

[0006] A third object of the present invention is to provide an application of an indium-based catalyst modified with copper-nickel dual atoms.

[0007] In the first aspect, the present invention provides a preparation method of an indium-based catalyst modified with copper-nickel dual atoms, including the following steps:

[0008] S1. Provide an indium oxide nanotube support;

[0009] S2. In a photoreactor, add the indium oxide nanotube support and water, and then add ethanol to obtain a mixed solution. First, add a copper source solution to the mixed solution, irradiate it with a light source, then add a nickel source solution, and irradiate it with a light source. The obtained solid is freeze-dried to obtain an indium-based catalyst modified with copper-nickel dual atoms.

[0010] Step S1:

[0011] The indium oxide nanotube carrier is prepared by a metal organic framework template method, and the specific preparation method comprises the following steps: indium nitrate and terephthalic acid are respectively dissolved in N, N-dimethylformamide, fully mixed and stirred, and then hydrothermally heated at 100° C. for 24 hours; after the reaction is completed, the solid-liquid separation is performed, the reaction is washed, dried, and calcined at 500° C. for 2 hours to obtain the indium oxide nanotube carrier.

[0012] The nanotubes of the indium oxide nanotube carrier have a length of 10 to 20 μm and a diameter of 1 to 2 μm; the tube wall is composed of nano-microspheres.

[0013] Step S2:

[0014] The active metal in the copper-nickel diatomic modified indium-based catalyst is introduced by a step-by-step photodeposition method, and the deposition sequence is to deposit metal copper first and then metal nickel, and the loading sequence plays a key role.

[0015] In some embodiments, the mixing ratio of the indium oxide nanotube carrier, water and ethanol is 200 mg:95 mL:5 mL.

[0016] In some embodiments, the copper source is one or more of copper chloride, copper nitrate, and copper citrate, preferably copper chloride; the nickel source is one or more of nickel nitrate, nickel chloride, and nickel acetylacetonate, preferably nickel nitrate.

[0017] In some embodiments, relative to the indium oxide nanotube carrier, the mass fraction of the copper element is 0.1-2.5 wt%, preferably 0.6 wt%; the mass fraction of the nickel element is 0.1-2.5 wt%, preferably 0.6 wt%.

[0018] In some embodiments, the light source is a mercury lamp, the power of the mercury lamp is 500 W, and the irradiation time is 3-6 hours.

[0019] Specifically, step S2 includes the following steps: the catalyst copper active species is introduced by photodeposition, deionized water is taken into a photoreactor with a quartz window, ethanol is added as a hole sacrificial agent, and then the above-mentioned indium oxide nanotube carrier and copper source precursor solution are added; after the reactor is sealed, the air is exhausted by argon purge; the mercury lamp is continuously used for 3 hours, and the mixture is cooled by circulating water and stirred; after the reaction is completed, the nickel source precursor solution is added to the reactor, and the mercury lamp is used for 3 hours again, and the mixture is cooled by circulating water and stirred; after the reaction is completed, the solid product is separated by suction filtration, and the solid product is freeze-dried after multiple washing to obtain a copper nickel-indium oxide catalyst.

[0020] In a second aspect, the present invention provides a copper-nickel diatom-modified indium-based catalyst prepared by the above preparation method.

[0021] In the indium-based catalyst of the present invention, copper-nickel dual-atom species are introduced as the active component, which can be used as a catalyst for catalytic oxidation of coalbed methane to methanol.

[0022] In a third aspect, the present invention provides a method for catalytic oxidation of coalbed methane to methanol, comprising the following steps:

[0023] Charge coalbed methane into a reaction kettle containing the copper-nickel dual-atom modified indium-based catalyst, and add hydrogen peroxide as an oxidant; raise the temperature and stir the mixture for reaction, and collect the produced methanol from the liquid phase after the reaction ends.

[0024] Preferably, the volume concentration of methane in the coalbed methane is 99.9%.

[0025] Preferably, the pressure of the coalbed methane is 3 MPa; the reaction temperature is 70 °C, the stirring rate is 800 rpm, and the reaction time is 0.5 - 1 hour.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] In the method for preparing the catalyst provided by the present invention, an indium oxide nanotube support with a special morphology is constructed by the metal-organic framework template method. The support has indium vacancies, which can be adapted to copper atoms. Under photoexcitation, a composite coordination structure similar to indium oxide-cuprous oxide is formed through the strong interaction between indium oxide and copper species. On this basis, nickel ions are adsorbed near the copper species by the affinity of the copper species for the nickel precursor salt to form copper-nickel species, making the prepared copper-nickel-indium oxide catalyst particularly suitable for the reaction of catalytic oxidation of coalbed methane to methanol, especially achieving a high methanol yield (>6000 μmol / g 2+ / h) under relatively mild conditions. cat / h) implementation results.

[0028] The present invention has been described in detail above, but the above embodiments are essentially illustrative only and are not intended to limit the present invention. In addition, the present invention is not limited by any theory described in the foregoing prior art or the invention content or the following examples.

[0029] Unless otherwise expressly stated, numerical ranges in the entire application document include any sub-ranges therein and any numerical values incremented by the smallest sub-units of the given values therein. Unless otherwise expressly stated, numerical values in the entire application document represent approximate measures or limitations of ranges of embodiments including minor deviations from the given values, as well as embodiments having approximately the recited values and having the recited exact values. Except for the working examples provided at the end of the detailed description, all numerical values of parameters (e.g., quantities or conditions) in this application document (including the appended claims) should be understood to be modified by the term "about" in all cases, whether or not "about" actually appears before the numerical value. "About" means that the stated numerical value allows for some imprecision (some approximation to exactness in that value; approximately or reasonably close to that value; approximate). If the imprecision provided by "about" is not understood in this ordinary sense in the art, then "about" as used herein means at least the variations that can be produced by measurement and ordinary methods of using these parameters. For example, "about" can include variations of less than or equal to 10%, less than or equal to 5%, less than or equal to 4%, less than or equal to 3%, less than or equal to 2%, less than or equal to 1%, or less than or equal to 0.5%. Description of the Drawings

[0030] Figure 1 Scanning electron microscope images and high-magnification scanning electron microscope images of indium oxide nanotubes obtained in Example 1 of the present invention;

[0031] Figure 2 UV-visible diffuse reflectance images of indium oxide nanotubes obtained in Example 1 of the present invention and commercially available indium oxide without morphology;

[0032] Figure 3 Yield graphs of the production of methanol by catalytic conversion of coalbed methane using indium oxide nanotubes prepared in Example 1 of the present invention and commercially available indium oxide without morphology;

[0033] Figure 4 Scanning electron microscope scan of the copper-nickel / indium oxide nanotube catalyst obtained in Example 2;

[0034] Figure 5 EDX elemental mapping spectra of the copper-nickel / indium oxide nanotube catalyst obtained in Example 2;

[0035] Figure 6 Yield graphs of the production of methanol by catalytic conversion of coalbed methane using the copper-nickel / indium oxide catalysts prepared in Example 2 and Comparative Examples 1-3;

[0036] Figure 7 Yield graphs of the production of methanol by catalytic conversion of coalbed methane using the copper-nickel / indium oxide catalysts prepared in Comparative Examples 4-7;

[0037] Figure 8This is a graph showing the yield of methanol produced from coalbed methane catalyzed by copper nickel-indium oxide prepared in comparative examples 8-10. DETAILED DESCRIPTION

[0038] The present invention is further described below in conjunction with examples. It should be noted that the following examples are provided for illustrative purposes only and do not constitute a limitation on the scope of protection claimed for the present invention.

[0039] Unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources.

[0040] Example 1

[0041] Indium oxide nanotube catalyst was prepared in this example:

[0042] 7.6mmol In(NO3)3·xH2O (hydrated indium nitrate) was dissolved in 12.4mL N,N-dimethylformamide, which was recorded as solution A, and 2.6mmol terephthalic acid was also dissolved in 12.4mL N,N-dimethylformamide, which was recorded as solution B. After the added precursor solid was completely dissolved, the A and B solutions were mixed and fully stirred, and then the mixed solution was placed in a 50mL autoclave and kept at 100°C for 24 hours to obtain a soft white block solid, which was recorded as InMOF. It was centrifuged from the incompletely reacted solution, and after repeated washing with deionized water and methanol, the insoluble white solid was dried in an oven at 60°C for 24 hours to completely remove the residual water and organic solvent impurities. The dried white solid was placed in a vacuum drying oven at 150°C for 2 hours, and then the sample was calcined at 500°C for 2 hours at a heating rate of 5°C / min. The resulting product was an indium oxide nanotube catalyst, which was recorded as InNT. The scanning electron microscope scan is shown in Figure 1 The catalytic performance of the InNT catalyst prepared in this example was tested in a closed reactor under the following test conditions: 3.0 MPa coalbed methane was charged into a reactor filled with 19 mL of deionized water, 1 mL of 30% hydrogen peroxide, and 5 mg of the above catalyst; the temperature was raised to 70°C and stirred at 800 rpm for 30 minutes, and the methanol produced was collected by distillation from the liquid phase in the reactor.

[0043] Methanol was analyzed off-line by GC-1690 gas chromatograph equipped with a hydrogen flame detector.

[0044] Methanol yield (μmol 甲醇 / g cat / h)=(C 甲醇 ×V) / M cat / t,

[0045] C 甲醇: Methanol concentration measured by GC (μmol / L), V: Volume of the liquid collected by condensation (L), M cat : Mass of the catalyst (g), t: Reaction duration (h).

[0046] In this example, indium oxide nanotube catalyst was prepared by the metal-organic framework template method, labeled as InNT. Its morphology is a hollow hexagonal prism with a diameter of 1-2 μm and a length of 10-20 μm, and its surface is composed of multiple microspheres. Its methanol yield is 2813.57 μmol / g cat / h( Figure 3 ), which is higher than that of commercial indium oxide without morphology.

[0047] Example 2

[0048] In this example, copper-nickel / indium oxide catalyst was prepared by the stepwise photodeposition method: In a photoreactor with a quartz window, 200 mg of InNT support and 95 mL of distilled water were added, and then 5 mL of ethanol was added as a sacrificial agent. 382 μL of 50 mM copper chloride solution was added to the solution. After irradiating with a 500 W mercury lamp for 3 hours, 382 μL of 50 mM nickel nitrate solution was added to the reactor, and the mercury lamp was used again to irradiate for 3 hours. During the photodeposition process, the reactor was kept sealed and argon was introduced to exclude air interference, and stirring was maintained at 250 rpm. All procedures involving light irradiation were introduced with circulating water cooling to keep the reaction temperature at 25 °C to avoid premature aggregation and denaturation of the precursor metal salts. Finally, the solid after photodeposition was collected by suction filtration and freeze-dried to obtain the CuNi / InNT catalyst. Its scanning electron microscope scanning image is as Figure 4 shown, and the metal loading situation is as Figure 5 shown. The catalytic performance of the CuNi / InNT catalyst prepared in this example was tested in a closed reaction kettle. The test conditions were as follows: 3.0 MPa coalbed methane was charged into a reaction kettle filled with 19 mL of deionized water, 1 mL of 30% hydrogen peroxide, and 5 mg of the above catalyst; after heating to 70 °C and stirring at 800 rpm for 30 minutes, methanol produced was distilled and collected from the liquid phase in the reaction kettle.

[0049] In this example, copper-nickel / indium oxide was prepared by the stepwise photodeposition method in the order of preferentially depositing metal copper and then depositing metal nickel, labeled as CuNi / InNT, and its methanol yield was 6500.68 μmol / g cat / h.

[0050] Comparative Example 1

[0051] The difference between this example and Example 2 is that the support used was changed from InNT to commercial indium oxide (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., without a specific morphology, Figure 2This is the high ultraviolet-visible diffuse reflectance diagram of indium oxide nanotubes and commercial indium oxide in the present invention. It can be seen that there are no metal indium vacancies in commercial indium oxide. The obtained copper-nickel-indium oxide catalyst is denoted as CuNi / In2O3, and the others are the same as in Example 2. The calculated methanol yield is as Figure 6 shown.

[0052] Comparative Example 2

[0053] The difference between this example and Example 2 is that the volume of the nickel nitrate precursor solution added is increased to 1.53 mL, and the Ni mass fraction in the obtained Cu1Ni4 / InNT catalyst is increased from 0.6 wt% to 2.4 wt%. The calculated methanol yield is as Figure 6 shown.

[0054] Comparative Example 3

[0055] The difference between this example and Example 2 is that the volume of the copper chloride and nickel nitrate precursor solutions added is increased to 1.53 mL, and the Cu and Ni mass fractions in the obtained Cu4Ni4 / InNT catalyst are increased from 0.6 wt% to 2.4 wt%. The calculated methanol yield is as Figure 6 shown.

[0056] Comparative Example 4

[0057] This comparative example prepares a copper-indium oxide catalyst: In a photoreactor with a quartz window, 200 mg of InNT support and 95 mL of distilled water are added, and then 5 mL of ethanol is added as a sacrificial agent. 382 μL of 50 mM copper chloride solution is added to the solution. During the photodeposition process, the reactor is kept sealed and argon is introduced, stirring is maintained at 250 rpm, circulating water is introduced for cooling, and the temperature is kept at 25 °C. The solid after photodeposition is collected by suction filtration and freeze-dried to obtain the copper-indium oxide catalyst, denoted as Cu / InNT. The catalytic performance of the catalyst is tested by the same method as in Example 2, and the calculated methanol yield is as Figure 7 shown.

[0058] Comparative Example 5

[0059] This comparative example prepares a nickel-indium oxide catalyst: In a photoreactor with a quartz window, 200 mg of InNT support and 95 mL of distilled water are added, and then 5 mL of ethanol is added as a sacrificial agent. 382 μL of 50 mM nickel nitrate solution is added to the solution. During the photodeposition process, the reactor is kept sealed and argon is introduced, stirring is maintained at 250 rpm, circulating water is introduced for cooling, and the temperature is kept at 25 °C. The solid after photodeposition is collected by suction filtration and freeze-dried to obtain the copper-indium oxide catalyst, denoted as Ni / InNT. The catalytic performance of the catalyst is tested by the same method as in Example 2, and the calculated methanol yield is as Figure 7as shown

[0060] Comparative Example 6

[0061] In this comparative example, a copper-nickel-indium oxide catalyst with a different stepwise photo-deposition sequence was prepared: In a photoreactor with a quartz window, 200 mg of InNT support and 95 mL of distilled water were added, and then 5 mL of ethanol was added as a sacrificial agent. First, 382 μL of 50 mM nickel nitrate solution was added to the solution, and after irradiating with a 500 W mercury lamp for 3 hours, 382 μL of 50 mM copper chloride solution was added to the reactor, and the mercury lamp was used for irradiation again for 3 hours. During the photo-deposition process, the reactor was kept sealed and argon was introduced, stirring was maintained at 250 rpm, circulating water was introduced for cooling, and the temperature was maintained at 25 °C. The solid after photo-deposition was collected by suction filtration and freeze-dried to obtain a copper-nickel-indium oxide catalyst with a different photo-deposition sequence from that of Example 2, denoted as NiCu / InNT. The catalytic performance of the catalyst was tested by the same method as in Example 2, and the calculated results of its methanol yield are as Figure 7 as shown

[0062] Comparative Example 7

[0063] In this comparative example, a copper-nickel-indium oxide catalyst with a different stepwise photo-deposition sequence was prepared: In a photoreactor with a quartz window, 200 mg of InNT support and 95 mL of distilled water were added, and then 5 mL of ethanol was added as a sacrificial agent. At the same time, 382 μL of 50 mM nickel nitrate solution and 382 μL of 50 mM copper chloride solution were added to the solution, and it was irradiated with a mercury lamp for 3 hours. During the photo-deposition process, the reactor was kept sealed and argon was introduced, stirring was maintained at 250 rpm, circulating water was introduced for cooling, and the temperature was maintained at 25 °C. The solid after photo-deposition was collected by suction filtration and freeze-dried to obtain a copper-nickel-indium oxide catalyst with a different photo-deposition sequence from that of Example 2, denoted as NiCu@InNT. The catalytic performance of the catalyst was tested by the same method as in Example 2, and the calculated results of its methanol yield are as Figure 7 as shown

[0064] Comparative Example 8

[0065] This comparative example prepares a copper - indium oxide catalyst: In a photoreactor with a quartz window, 200 mg of InNT support and 95 mL of distilled water are added, and then 5 mL of ethanol is added as a sacrificial agent. First, 382 μL of 50 mM copper chloride solution is added to the solution. After irradiating with a 500 W mercury lamp for 3 hours, another 382 μL of 50 mM copper chloride solution is added to the reactor, and the mercury lamp is used again to irradiate for 3 hours. During the photodeposition process, the reactor is kept sealed and argon is introduced, stirring is maintained at 250 rpm, circulating water is introduced for cooling, and the temperature is kept at 25 °C. The solid after photodeposition is collected by suction filtration and freeze - dried to obtain the copper - indium oxide catalyst, denoted as CuCu / InNT. The catalytic performance of the catalyst is tested by the same method as in Example 2, and the calculated methanol yield is as shown in Figure 8 shown.

[0066] Comparative Example 9

[0067] This comparative example prepares a copper - palladium - indium oxide catalyst: In a photoreactor with a quartz window, 200 mg of InNT support and 95 mL of distilled water are added, and then 5 mL of ethanol is added as a sacrificial agent. First, 382 μL of 50 mM copper chloride solution is added to the solution. After irradiating with a 500 W mercury lamp for 3 hours, 1.91 mL of 10 mM palladium chloride solution is added to the reactor, and the mercury lamp is used again to irradiate for 3 hours. During the photodeposition process, the reactor is kept sealed and argon is introduced, stirring is maintained at 250 rpm, circulating water is introduced for cooling, and the temperature is kept at 25 °C. The solid after photodeposition is collected by suction filtration and freeze - dried to obtain the copper - palladium - indium oxide catalyst, denoted as CuPd / InNT. The catalytic performance of the catalyst is tested by the same method as in Example 2, and the calculated methanol yield is as shown in Figure 8 shown.

[0068] Comparative Example 10

[0069] This comparative example prepares a copper - zinc - indium oxide catalyst: In a photoreactor with a quartz window, 200 mg of InNT support and 95 mL of distilled water are added, and then 5 mL of ethanol is added as a sacrificial agent. First, 382 μL of 50 mM copper chloride solution is added to the solution. After irradiating with a 500 W mercury lamp for 3 hours, 382 μL of 50 mM zinc chloride solution is added to the reactor, and the mercury lamp is used again to irradiate for 3 hours. During the photodeposition process, the reactor is kept sealed and argon is introduced, stirring is maintained at 250 rpm, circulating water is introduced for cooling, and the temperature is kept at 25 °C. The solid after photodeposition is collected by suction filtration and freeze - dried to obtain the copper - zinc - indium oxide catalyst, denoted as CuZn / InNT. The catalytic performance of the catalyst is tested by the same method as in Example 2, and the calculated methanol yield is as shown in Figure 8 shown.

[0070] Figure 7 andFigure 8 For the yield changes of single-metal copper / nickel, different photo-deposition sequences, and indium oxide catalysts doped with different active components in the selective oxidation reaction of coalbed methane, it can be seen from the results that the CuNi / InNT catalyst has the highest yield of methanol.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a copper-nickel dual-atom modified indium-based catalyst, characterized in that, Comprising the following steps: S1. Provide an indium oxide nanotube support; S2. In a photoreactor, add the indium oxide nanotube support and water, then add ethanol to obtain a mixed solution. First, add a copper source solution to the mixed solution, irradiate it with a light source, then add a nickel source solution, and irradiate it with a light source. The obtained solid is freeze-dried to obtain a copper-nickel dual-atom modified indium-based catalyst.

2. The preparation method according to claim 1, characterized in that, The preparation method of the indium oxide nanotube support in step S1 comprises the following steps: Dissolve indium nitrate and terephthalic acid in N,N-dimethylformamide respectively, fully mix and stir, and perform hydrothermal treatment at 100 °C for 24 hours; after the reaction, perform solid-liquid separation, wash and dry, and calcine at 500 °C for 2 hours to obtain the indium oxide nanotube support.

3. The preparation method according to claim 1, characterized in that, In step S2, the mixing ratio of the indium oxide nanotube support, water and ethanol is 200 mg: 95 mL: 5 mL.

4. The preparation method according to claim 1, characterized in that, In step S2, the copper source is one or more of copper chloride, copper nitrate, and copper citrate; the nickel source is one or more of nickel nitrate, nickel chloride, and nickel acetylacetonate.

5. The preparation method according to claim 1, characterized in that, In step S2, relative to the indium oxide nanotube support, the mass fraction of copper element is 0.1-2.5 wt%, preferably 0.6 wt%; the mass fraction of nickel element is 0.1-2.5 wt%, preferably 0.6 wt%.

6. The preparation method according to claim 1, wherein In step S2, the light source is a mercury lamp, the power of the mercury lamp is 500 W, and the irradiation time each time is 3-6 hours.

7. A copper-nickel dual-atom modified indium-based catalyst, characterized in that, Prepared by the preparation method according to any one of claims 1-6.

8. A method for catalytic oxidation of coalbed methane to methanol, characterized in that, Comprising the following steps: Charge coalbed methane into a reaction kettle containing the copper-nickel dual-atom modified indium-based catalyst according to claim 7, and add hydrogen peroxide as an oxidant; raise the temperature and stir the mixture for reaction, and collect the produced methanol from the liquid phase after the reaction.

9. The method according to claim 8, characterized in that, The volume concentration of methane in the coalbed methane is 99.9%.

10. The method according to claim 8, characterized in that, The pressure of the coalbed methane is 3 MPa; the reaction temperature is 70 °C, the stirring rate is 800 rpm, and the reaction time is 0.5-1 hour.

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