A method for preparing a supported carbon-doped noble metal nanoparticle catalyst

Abstract

The application discloses a preparation method of a supported carbon-doped noble metal nanoparticle catalyst and belongs to the technical field of nanometer material catalyst synthesis. The supported carbon-doped noble metal nanoparticle catalyst is prepared by using a colloidal reduction method, and carbon-doped noble metal nanoparticle catalyst is generated through the interaction between C residues of a surfactant and noble metal under high-temperature conditions, wherein the noble metal is one of Ru, Rh, Pd, Os, Ir, Pt, Au and Ag; and the calcination temperature is 500-1300 DEG C, preferably 600-900 DEG C. The method is simple in operation and easy to control, and provides support for the wide application of the supported carbon-doped noble metal nanoparticle catalyst.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterial catalyst synthesis, specifically relating to a method for preparing supported carbon-doped noble nanoparticle catalysts using a heat-treated colloidal method. Background Technology

[0002] In industrial catalysis, carbon doping is a commonly used method for catalyst modification. By depositing carbon atoms on the metal surface and diffusing them into the crystal lattice, the electronic properties of the catalyst can be significantly altered, leading to its wide applications in catalysis, such as selective hydrogenation, selective dehydrogenation, methane aromatization, Fischer-Tropsch synthesis, carbon dioxide conversion, and electrocatalysis (CN115910631A, CN105749947A). From the modification of metal nanoparticles themselves to the modification of the support (CN103623820A), carbon doping has significant application value. Research on carbon doping of non-noble metals is relatively extensive, focusing on transition metals such as Fe, Mn, and Ni. The preparation and application of these carbides have been widely reported.

[0003] Carbon-doped noble metal nanoparticles significantly enhance catalyst performance. For example, Schlogl et al. reported the formation of interstitial C atoms in a Pd catalyst during alkyne hydrogenation, which significantly improved the selectivity of alkyne hydrogenation to olefins (Science, 2008, 320, 86-89). Traditional extreme or complex synthesis conditions limit the research on carbon-doped noble metals. Examples include: calcining transition metal salts with aqueous organic acid solutions in a carbon-containing atmosphere to prepare palladium carbide (CN109772396A); using molecular sieves to assist in the synthesis of supported palladium carbide catalysts (CN115770606A); and using hydrothermal methods to synthesize gold catalysts in ordered mesoporous carbon nanospheres (Nature Communications, 2020, 11, 4600). These methods are demanding and cumbersome, preventing large-scale industrial applications. Therefore, the research and utilization of carbon-doped noble metals are currently insufficient. Developing simple and easy-to-implement processing conditions is extremely important. Summary of the Invention

[0004] Therefore, the purpose of this invention is to provide a method for preparing supported carbon-doped noble metal nanoparticle catalysts, which is simple to operate, easy to implement, and low in cost.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing a supported carbon-doped noble metal nanoparticle catalyst mainly includes the following steps:

[0007] (1) Weigh the precursor of the precious metal and the surfactant at a mass ratio of 1:0.5 to 1:100;

[0008] (2) Dissolve the surfactant weighed in step (1) in deionized water to obtain an aqueous surfactant solution;

[0009] (3) Add the precursor of the precious metal weighed in step (1) to deionized water, dissolve it, add the surfactant aqueous solution in step (2), stir at room temperature to obtain a sol.

[0010] (4) Weigh the carrier according to a metal loading of 0.1-10 wt%;

[0011] (5) Add the carrier weighed in step (4) to the sol in step (3) and stir;

[0012] (6) Adjust the pH of the mixed solution in step (5) to 2-5 so that the sol is completely loaded on the carrier;

[0013] (7) Remove the unreacted substances and impurity ions from step (6) by vacuum filtration and washing the solid sample until neutral;

[0014] (8) Dry the solid sample obtained in step (7) to obtain solid powder;

[0015] (9) Grind the solid powder obtained in step (8) and calcine it at 500-1300℃ for 2-10 hours to obtain a supported carbon-doped noble metal nanoparticle catalyst.

[0016] Based on the above technical solution, further, the precious metal mentioned in step (1) is one or more of Ru, Rh, Pd, Os, Ir, Pt, Au, and Ag.

[0017] Based on the above technical solution, further, the surfactant mentioned in step (1) is one or a combination of two or more of polyvinylpyrrolidone, ethylene glycol, polyvinyl alcohol, hexadecyltrimethylammonium bromide, methylcellulose, and sodium citrate.

[0018] Based on the above technical solution, further, the concentrations of the surfactant aqueous solution in step (2) and the noble metal precursor solution in step (3) are 0.1 to 1 g / mL.

[0019] Based on the above technical solution, further, the carrier in step (4) is one or more of titanium oxide, aluminum oxide, silicon oxide, magnesium oxide, lanthanum oxide, zinc oxide, cerium oxide, and zirconium oxide.

[0020] Based on the above technical solution, further, the particle size after grinding in step (9) is 20 to 200 mesh.

[0021] Based on the above technical solution, further, the roasting atmosphere in step (9) contains oxygen, and the volume content of the oxygen is 0.1-50%.

[0022] Based on the above technical solution, further, the roasting temperature in step (9) is 600-900℃.

[0023] The present invention also provides a supported carbon-doped noble metal nanoparticle catalyst prepared by the above preparation method.

[0024] The present invention also provides the application of the above-mentioned supported carbon-doped noble metal nanoparticle catalyst in the catalytic preparation of chloroaniline from chloronitrobenzene.

[0025] The advantages of this invention over the prior art are as follows:

[0026] This invention utilizes a colloidal reduction method to prepare a supported carbon-doped noble metal nanoparticle catalyst. The catalyst is generated by the interaction between the residual carbon of the surfactant and the noble metal under high temperature conditions. The method is simple, easy to control, and low in cost, providing strong support for the widespread application of supported carbon-doped noble metal nanoparticle catalysts. Attached Figure Description

[0027] To more clearly illustrate the embodiments of the present invention, the accompanying drawings involved in the embodiments will be briefly described below.

[0028] Figure 1 The Raman spectrum of the Pt-P-600 catalyst prepared in Example 1;

[0029] Figure 2 The Raman spectrum of the Pt-P-800 catalyst prepared in Example 2;

[0030] Figure 3 The Raman spectrum of the Pt-P-300 catalyst prepared in Comparative Example 1;

[0031] Figure 4 The Raman spectrum of the Pt-I-600 catalyst prepared in Comparative Example 2 is shown. Detailed Implementation

[0032] The present invention will be described in detail below with reference to the embodiments. However, the implementation of the present invention is not limited thereto. Obviously, the embodiments described below are only some embodiments of the present invention. For those skilled in the art, other similar embodiments can be obtained without creative effort and all fall within the protection scope of the present invention.

[0033] In the embodiments, the presence of metal carbides was determined using a micro-La Mans technique.

[0034] Example 1

[0035] The preparation method of Pt-P-600 includes the following steps:

[0036] (1) Material weighing: Weigh chloroplatinic acid and methylcellulose at a mass ratio of 1:5;

[0037] (2) Introduction of surfactant: Dissolve the methylcellulose weighed in step (1) in deionized water (concentration of 0.5 mg / mL), heat in a water bath and stir until completely dissolved;

[0038] (3) Preparation of Pt sol: The chloroplatinic acid weighed in step (1) is added to deionized water (concentration of 5 mg / mL) and dissolved to form a chloroplatinic acid solution. The methylcellulose aqueous solution prepared in step (2) is added to it. Pt sol is prepared by stirring at room temperature.

[0039] (4) Weighing of TiO2 material: Weigh TiO2 according to a metal loading of 0.1%;

[0040] (5) Loading of Pt / TiO2: Add the TiO2 weighed in step (4) to the solution in step (3) and stir;

[0041] (6) Adjust pH: Adjust the pH of the mixed solution in step (5) to 3 so that the platinum sol is completely loaded on the carrier;

[0042] (7) Removal of surfactants and impurity ions: The unreacted substances and impurity ions in the loading described in step (6) are removed by vacuum filtration and washing of the solid sample, and the catalyst is washed until neutral.

[0043] (8) Catalyst drying: The solid sample after filtration in step (7) is placed in a vacuum drying oven and dried to obtain Pt / TiO2 catalyst.

[0044] (9) Catalyst calcination: The solid powder obtained by drying in step (8) is ground and placed in a muffle furnace at 500°C for 5 hours to obtain Pt-P-600 catalyst.

[0045] The Raman spectrum of the Pt-P-600 catalyst prepared in Example 1 is as follows: Figure 1 As shown, according to the literature (Naturecommunications, 2016, 7, 12440; Chemical Physics Letters, 2013, 560, 42-48; ACS Materials Letters, 2021, 3, 179-186; Journal of Physics. Chemistry. Letters, 2013, 4, 892-896.), 240cm -1Tensile vibrations belonging to Pt-C2, 266 cm -1 Tensile vibrations belonging to Pt-C4, 443 cm -1 Belongs to Pt5-C + The tensile vibrations and the formation of Pt-C species can be clearly observed.

[0046] Example 2

[0047] The preparation method of Pt-P-800 includes the following steps:

[0048] (1) Material weighing: Weigh chloroplatinic acid and methylcellulose at a mass ratio of 1:2;

[0049] (2) Introduction of surfactant: Dissolve the methylcellulose weighed in step (1) in deionized water (concentration of 0.5 mg / mL), heat in a water bath and stir until completely dissolved;

[0050] (3) Preparation of Pt sol: The chloroplatinic acid weighed in step (1) is added to deionized water (concentration of 5 mg / mL) and dissolved to form a chloroplatinic acid solution. The methylcellulose aqueous solution prepared in step (2) is added to it. Pt sol is prepared by stirring at room temperature.

[0051] (4) Weighing of TiO2 material: Weigh TiO2 with a metal loading of 10%;

[0052] (5) Loading of Pt / TiO2: Add the TiO2 weighed in step (4) to the solution in step (3) and stir;

[0053] (6) Adjust pH: Adjust the pH of the mixed solution in step (5) to 5 so that the platinum sol is fully loaded on the carrier;

[0054] (7) Removal of surfactants and impurity ions: The unreacted substances and impurity ions in the loading described in step (6) are removed by vacuum filtration and washing of the solid sample, and the catalyst is washed until neutral.

[0055] (8) Catalyst drying: The solid sample after filtration in step (7) is placed in a vacuum drying oven and dried to obtain Pt / TiO2 catalyst.

[0056] (9) Catalyst calcination: The solid powder obtained by drying in step (8) is ground and calcined in a muffle furnace at 800°C for 5 hours to obtain Pt-P-800 catalyst.

[0057] The Raman spectrum of the Pt-P-800 catalyst prepared in Example 2 is as follows: Figure 2As shown, according to the literature (Naturecommunications, 2016, 7, 12440; Chemical Physics Letters, 2013, 560, 42-48; ACSMaterials Letters, 2021, 3, 179-186; Journal of Physics. Chemistry. Letters, 2013, 4, 892-896.), 240cm -1 Tensile vibrations belonging to Pt-C2, 266 cm -1 Tensile vibrations belonging to Pt-C4, 443 cm -1 Belongs to Pt5-C + The tensile vibrations and the formation of Pt-C species can be clearly observed.

[0058] Example 3

[0059] The preparation method of Ru-P-900 includes the following steps:

[0060] (1) Material weighing: Weigh ruthenium chloride and methylcellulose at a mass ratio of 1:100;

[0061] (2) Introduction of surfactant: Dissolve the methylcellulose weighed in step (1) in deionized water (concentration of 0.5 mg / mL), heat in a water bath and stir until completely dissolved;

[0062] (3) Preparation of Ru sol: The ruthenium chloride weighed in step (1) was added to deionized water (concentration of 5 mg / mL) and dissolved to form a ruthenium chloride solution. The methylcellulose aqueous solution prepared in step (2) was added to the solution. The solution was stirred at room temperature for 2 hours to prepare Ru sol.

[0063] (4) Weighing of TiO2 material: Weigh TiO2 according to a metal loading of 2%;

[0064] (5) Loading of Ru / TiO2: Add the TiO2 weighed in step (4) to the solution in step (3) and stir;

[0065] (6) Adjust pH: Adjust the pH of the mixed solution in step (5) to 2 so that the sol is fully loaded on the carrier;

[0066] (7) Removal of surfactants and impurity ions: The unreacted substances and impurity ions in the loading described in step (6) are removed by vacuum filtration and washing of the solid sample, and the catalyst is washed until neutral.

[0067] (8) Catalyst drying: The solid sample filtered in step (7) is placed in a vacuum drying oven and dried to obtain Ru / TiO2 catalyst.

[0068] (9) Catalyst calcination: The solid powder obtained by drying in step (8) is ground and calcined in a muffle furnace at 900°C for 5 hours to obtain Ru-P-900 catalyst.

[0069] Comparative Example 1

[0070] The preparation method of Pt-P-300 includes the following steps:

[0071] (1) Material weighing: Weigh chloroplatinic acid and methylcellulose at a mass ratio of 1:5;

[0072] (2) Introduction of surfactant: Dissolve the methylcellulose weighed in step (1) in deionized water (concentration of 0.5 mg / mL), heat in a water bath and stir until completely dissolved;

[0073] (3) Preparation of Pt sol: The chloroplatinic acid weighed in step (1) is added to deionized water (concentration of 5 mg / mL) and dissolved to form a chloroplatinic acid solution. The methylcellulose aqueous solution prepared in step (2) is added to it. Pt sol is prepared by stirring at room temperature.

[0074] (4) Weighing of TiO2 material: Weigh TiO2 according to a metal loading of 2%;

[0075] (5) Loading of Pt / TiO2: Add the TiO2 weighed in step (4) to the solution in step (3) and stir;

[0076] (6) Adjust pH: Adjust the pH of the mixed solution in step (5) to 3 so that the platinum sol is completely loaded on the carrier;

[0077] (7) Removal of surfactants and impurity ions: The unreacted substances and impurity ions in the loading described in step (6) are removed by vacuum filtration and washing of the solid sample, and the catalyst is washed until neutral.

[0078] (8) Catalyst drying: The solid sample after filtration in step (7) is placed in a vacuum drying oven and dried to obtain Pt / TiO2 catalyst.

[0079] (9) Catalyst calcination: The solid powder obtained from drying in step (8) is ground and placed in a muffle furnace and calcined at 300°C for 5 hours to obtain Pt-P-300 catalyst.

[0080] The Raman spectrum of the Pt-P-300 catalyst prepared in Comparative Example 1 is as follows: Figure 3 As shown, there is no signal in the spectrum.

[0081] Comparative Example 2

[0082] The preparation method of Pt-I-600 includes the following steps:

[0083] (1) Material weighing: Weigh chloroplatinic acid and TiO2 according to a metal loading of 10%;

[0084] (2) Preparation of chloroplatinic acid solution: Add the chloroplatinic acid weighed in step (1) to deionized water (concentration of 5 mg / mL) and dissolve to form chloroplatinic acid solution;

[0085] (3) Loading of Pt / TiO2: Add the TiO2 weighed in step (1) to the solution in step (2), and stir to make the chloroplatinic acid uniformly impregnated on the TiO2.

[0086] (4) Catalyst drying: The solid sample prepared in step (4) is placed in a vacuum drying oven and dried to obtain Pt / TiO2 catalyst;

[0087] (5) Catalyst calcination: The solid powder obtained from drying in step (8) is ground and calcined in a muffle furnace at 600°C for 5 hours to obtain Pt-I-600 catalyst.

[0088] Raman images of the Pt-I-600 catalyst prepared in Comparative Example 2 are shown below. Figure 4 As shown, there is no signal in the spectrum.

[0089] Comparative Example 3

[0090] The preparation method of Ru-I-800 includes the following steps:

[0091] (1) Material weighing: Weigh ruthenium chloride and TiO2 according to a metal loading of 5%;

[0092] (2) Preparation of chloroplatinic acid solution: Add the ruthenium chloride weighed in step (1) to deionized water (concentration of 5 mg / mL) and dissolve to form ruthenium chloride solution;

[0093] (3) Loading of Ru / TiO2: Add the TiO2 weighed in step (1) to the solution in step (2), and stir to impregnate and stir so that ruthenium chloride is evenly impregnated on TiO2;

[0094] (4) Catalyst drying: The solid sample prepared in step (4) is placed in a vacuum drying oven and dried to obtain Ru / TiO2 catalyst;

[0095] (5) Catalyst calcination: The solid powder obtained by drying in step (8) is ground and placed in a muffle furnace at 500°C for 5 hours to obtain Ru-I-500 catalyst.

[0096] Example 4

[0097] The catalytic activity of the catalysts prepared in Examples 1-3 and Comparative Examples 1-3 was evaluated using a batch reactor. 10 mg of catalyst sample, 165 mg of o-chloronitrobenzene, 20 μL of internal standard n-butanol, and 10 mL of ethanol solvent were weighed and added to a 25 mL high-pressure reactor. The reaction pressure was 2 MPa H2, and the reaction temperature was 100 °C. The conversion rate of the catalyst was controlled by adjusting the reaction time. GC-MS was used for qualitative and quantitative analysis of the reactants and products. Two indicators were used to determine the catalytic performance of the catalyst: (1) conversion rate at the same reaction time; (2) selectivity of the target product at the same conversion rate. The test results are shown in Table 1.

[0098] Table 1. Catalyst performance indicators in Examples 1-3 and Comparative Examples 1-3

[0099]

[0100] Table 1 shows that Examples 1, 2, and 3 all exhibit good o-chloroaniline selectivity, exceeding 99%, at the same conversion rate. The processing temperature of Example 1 is lower than that of Examples 2 and 3, mainly because it has a smaller average Pt particle size, thus exhibiting better catalytic activity. Comparative Example 1, under the same reaction conditions as Example 1, shows a target product selectivity of 82.2% and an aniline selectivity of 17.8%. Although it has smaller average Pt nanoparticles, its selectivity is extremely poor, indicating that calcination temperatures below 500°C reduce the target product selectivity and generate more aniline byproducts. Comparative Examples 2 and 3 have lower conversion rates and target product selectivities of 97%, and their catalytic performance is inferior to that of Examples 2 and 3, indicating that the surfactant plays an important role in the reaction. In summary, the data in Table 1 show that the surfactant used in this invention and processing conditions above 500°C can significantly improve the hydrogenation selectivity of the catalyst.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions 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. Use of a supported carbon-doped noble metal nanoparticle catalyst for the catalytic preparation of chloroaniline from chloronitrobenzene, characterized in that, The preparation method of the supported carbon-doped noble metal nanoparticle catalyst includes the following steps: (1) Weigh the precursor of the precious metal and the surfactant at a mass ratio of 1:0.5 to 1:100; (2) Dissolve the surfactant weighed in step (1) in deionized water to obtain an aqueous surfactant solution; (3) Add the precursor of the precious metal weighed in step (1) to deionized water, dissolve it, add the surfactant aqueous solution in step (2), stir at room temperature to obtain a sol; (4) Weigh the carrier according to a metal loading of 0.1-10 wt%; (5) Add the carrier weighed in step (4) to the sol in step (3) and stir; (6) Adjust the pH of the mixed solution in step (5) to 2-5 so that the sol is completely loaded on the carrier; (7) Remove the unreacted substances and impurity ions from step (6) by vacuum filtration and washing the solid sample until neutral; (8) Dry the solid sample obtained in step (7) to obtain solid powder; (9) Grind the solid powder obtained in step (8) and calcine it at 600-900℃ for 2-10 h to obtain a supported carbon-doped noble metal nanoparticle catalyst. The precious metal mentioned in step (1) is one or a combination of two of Ru and Pt; The surfactant mentioned in step (1) is one or a combination of two or more of the following: polyvinylpyrrolidone, ethylene glycol, polyvinyl alcohol, hexadecyltrimethylammonium bromide, methylcellulose, and sodium citrate. The carrier mentioned in step (4) is one or a combination of two or more of titanium oxide, aluminum oxide, silicon oxide, magnesium oxide, lanthanum oxide, zinc oxide, cerium oxide, and zirconium oxide; The concentrations of the surfactant aqueous solution in step (2) and the noble metal precursor solution in step (3) are 0.1~1 g / mL; The roasting atmosphere described in step (9) contains oxygen, and the volume content of the oxygen is 0.1-50%.

2. The application according to claim 1, characterized in that, The particle size after grinding in step (9) is 20~200 mesh.

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