Metal-free catalytic material as well as preparation method and application thereof

Abstract

The invention provides a metal-free catalytic material as well as a preparation method and application thereof. The preparation method of the metal-free catalytic material comprises the following steps: S1, mixing a fluosilicic acid solution and an alkaline organic solution to obtain a reaction solution; the alkaline organic solution comprises an organic substance, a template agent and an alkaline substance; the template agent comprises a cationic surfactant; s2, carrying out solid-liquid separation on the reaction liquid to obtain a solid isolate; the solid isolate is carbonized, the F / N-aCMs (at) SiO2 material is obtained, and the F / N-aCMs (at) SiO2 material is a metal-free catalytic material. According to the invention, the catalytic oxidation process of aldehyde substances can be directly realized without doping any metal, and the use of noble metal catalysts, organic solvents, strong oxidizing substances and the like is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalytic synthesis, in particular to a non-metallic catalytic material and a preparation method and application thereof. BACKGROUND

[0002] The catalytic oxidation of aldehyde substances into carboxylic acid substances is an important chemical synthesis reaction. Current oxidation methods include strong oxidant oxidation, metal catalyst catalytic oxidation, organic solvent catalytic oxidation, etc., but the above methods have great disadvantages in energy consumption, catalyst price, product recovery, etc. For example, strong oxidants require the use of strong oxidizing substances such as potassium permanganate and hydrogen peroxide, which are great problems for subsequent environmental treatment and synthesis cost; the use of metal catalysts is generally the use of noble metal catalysts, which have high production costs, and metal catalysts are easily deactivated; organic solvent catalysis is a homogeneous catalytic process, but this method requires separation and purification of the subsequent product, and the use of organic solvent catalysis also brings high cost and environmental problems.

[0003] In view of the defects of metal catalysts, non-metallic catalysts are considered in the research process. Non-metallic catalysts have a more stable structure, are not easily deactivated in the catalytic process, and are inexpensive, and the subsequent product separation is simple; however, the synthesis of such catalysts needs to be carbonized from high-polymer organic matter, and has specific requirements for the structure (such as graphene, C3N4, etc.), and there is currently a lack of a simple synthesis method for non-metallic catalysts with high catalytic activity and its application method.

[0004] Therefore, it is necessary to provide a non-metallic catalytic material and a preparation method and application thereof to solve or at least alleviate the technical problem of how to synthesize a non-metallic catalyst with high catalytic activity for aldehyde substances. SUMMARY

[0005] The main purpose of the present application is to provide a non-metallic catalytic material and a preparation method and application thereof, which aims to solve the above technical problem of how to synthesize a non-metallic catalyst with high catalytic activity for aldehyde substances.

[0006] To achieve the above purpose, the present application provides a preparation method of a non-metallic catalytic material, comprising the steps of:

[0007] S1, mixing a fluorosilicic acid solution and an alkaline organic solution to obtain a reaction liquid;

[0008] The alkaline organic solution comprises organic substances, a template agent and alkaline substances; the template agent comprises a cationic surfactant;

[0009] S2, the reaction liquid is solid-liquid separated to obtain a solid separation; the solid separation is carbonized to obtain the F / N-aCMs@SiO2 material, and the F / N-aCMs@SiO2 material is a metal-free catalytic material.

[0010] Further, the organic matter includes a dye organic matter with a benzene ring structure; the dye organic matter includes one or more of basic blue 7, solvent blue 38, methylene blue and reactive blue 21.

[0011] The cationic surfactant includes one or more of hexadecyl trimethyl ammonium bromide and hexadecyl trimethyl ammonium chloride.

[0012] The basic substance includes one or more of ammonia, sodium hydroxide and sodium carbonate.

[0013] Further, in the fluosilicic acid solution, the concentration of the fluosilicic acid is 0.1-0.7 mol / L.

[0014] In the basic organic solution, the concentration of the organic matter is 1-10 g / L, the concentration of the cationic surfactant is 1-10 g / L, and the concentration of the basic substance is 0.2-2 mol / L.

[0015] The volume ratio of the fluosilicic acid solution to the basic organic solution is 1:3-1:8.

[0016] The molar ratio of the fluosilicic acid to the basic substance is 1:4-1:10.

[0017] Further, in the step S1, the temperature of mixing is 50-100 DEG C, and the mixing time is 2-8 h.

[0018] Further, the carbonization is carried out under the protection of an inert atmosphere; the temperature of the carbonization is 400-700 DEG C, and the time of the carbonization is 30-180 min.

[0019] Further, the step S2 further includes: before the carbonization, the solid separation is subjected to a drying treatment.

[0020] The application further provides a metal-free catalytic material, which is prepared by using any of the preparation methods described above.

[0021] The application further provides an application of the metal-free catalytic material described above in photocatalysis of aldehyde matter.

[0022] Further, the aldehyde matter includes one or more of benzaldehyde, cinnamaldehyde, p-bromobenzaldehyde, p-methoxybenzaldehyde, p-methylbenzaldehyde, p-chlorobenzaldehyde and o-methoxybenzaldehyde.

[0023] Further, the mass ratio of the non-metallic catalytic material to the aldehyde substance is 1:25-1:100; and the length of the photocatalysis is 3-12 hours.

[0024] Compared with the prior art, the present application has at least the following advantages:

[0025] The non-metallic catalyst with high catalytic activity for aldehyde substances is synthesized, and the problems of complex synthesis and low activity of aldehyde non-metallic catalysts are solved. In the present application, the cationic surfactant and organic matter are cooperatively assembled to form a micellar structure by a co-precipitation process of fluorosilicic acid solution and alkaline organic solution, and the organic matter is loaded on the surface of the silica; then the mesoporous silica is formed by removing the micellar structure through a carbonization process, and the F / N-aCMs@SiO2 material is formed. In the application process, the F / N-aCMs@SiO2 material and the aldehyde substance are subjected to a photocatalytic reaction under light irradiation, and the catalytic oxidation of the aldehyde substance to form a carboxylic acid substance is realized directly without any metal doping, thereby avoiding the use of noble metal catalysts, organic solvents and strong oxidizing substances. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the following embodiment or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor based on the drawings shown.

[0027] Figure 1 TEM image of the sample after carbonization in Example 1 of the present application;

[0028] Figure 2 a is the nitrogen adsorption-desorption curve of the sample after carbonization in Example 1 of the present application, Figure 2 b is the pore size distribution graph of the sample after carbonization in Example 1 of the present application;

[0029] Figure 3 TEM-EDS image of the sample after carbonization in Example 1 of the present application; in the figure, (a) is a TEM image, (b) is a C element energy spectrum graph, (c) is a N element energy spectrum graph, (d) is an O element energy spectrum graph, (e) is an F element energy spectrum graph, and (f) is a Si element energy spectrum graph;

[0030] Figure 4 a is the N1s graph of the XPS spectrum of the sample after carbonization in Example 1 of the present application, Figure 4 b is the F1s graph of the XPS spectrum of the sample after carbonization in Example 1 of the present application;

[0031] Figure 5 Conversion rate of the product after reaction in Examples 2-7 of the present application; in the figure, 1:100 corresponds to the conversion rate of benzaldehyde in Example 2, 1:67 corresponds to the conversion rate of benzaldehyde in Example 3, 1:50 corresponds to the conversion rate of benzaldehyde in Example 4, 1:40 corresponds to the conversion rate of benzaldehyde in Example 5, 1:33 corresponds to the conversion rate of benzaldehyde in Example 6, and 1:28 corresponds to the conversion rate of benzaldehyde in Example 7;

[0032] Figure 6 Conversion rate of the product after reaction in Examples 8-12 of the present application; in the figure, 1h corresponds to Example 8, 2h corresponds to Example 9, 3h corresponds to Example 10, 4h corresponds to Example 11, and 6h corresponds to Example 12;

[0033] Figure 7 Conversion rate of the product after reaction in Examples 13-19 of the present application; in the figure, benzaldehyde, p-methoxybenzaldehyde, p-methylbenzaldehyde, p-chlorobenzaldehyde, o-methoxybenzaldehyde, p-bromobenzaldehyde, and cinnamaldehyde correspond to Examples 13-19, respectively;

[0034] Figure 8 TEM image of the sample after carbonization in Comparative Example 1 of the present application;

[0035] Figure 9 a nitrogen adsorption-desorption curve of the sample after carbonization in Comparative Example 1 of the present application, Figure 9 b pore size distribution of the sample after carbonization in Comparative Example 1 of the present application;

[0036] Figure 10 TEM image of the sample after carbonization in Comparative Example 2 of the present application;

[0037] Figure 11 a N1s spectrum of the XPS spectrum of the sample after carbonization in Comparative Example 2 of the present application, Figure 11 b F1s spectrum of the XPS spectrum of the sample after carbonization in Comparative Example 2 of the present application.

[0038] The implementation, functional features and advantages of the present application will be further described with reference to the accompanying drawings. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0040] Moreover, the technical solutions among the various embodiments of the present application can be combined with each other, but it must be based on the fact that a person skilled in the art can realize the combination, and when the combination of the technical solutions appears contradictory or unachievable, it should be considered that the combination of the technical solutions does not exist and is not within the protection scope required by the present application.

[0041] When the embodiments give a numerical range, it should be understood that, unless otherwise stated by the present application, both ends of each numerical range and any number between the two ends can be selected. Unless otherwise defined, all technical and scientific terms used in the present application are consistent with the mastery of the prior art by the person skilled in the art and the description of the present application, and any method, equipment and material of the prior art similar or equivalent to the method, equipment and material described in the embodiments of the present application can be used to realize the present application. In the present application, the calculation process of the conversion rate (yield) is: yield = (amount of substance of generated carboxylic acid / amount of substance of initial aldehyde) * 100%, and the yield is directly calculated by nuclear magnetic resonance hydrogen spectrum.

[0042] The present application provides a preparation method of a non-metallic catalytic material, comprising the steps of:

[0043] S1, mixing a fluosilicic acid solution and a basic organic solution to obtain a reaction solution.

[0044] In the present application, the basic organic solution comprises an organic substance, a template agent and a basic substance; the template agent comprises a cationic surfactant.

[0045] In the present application, the organic substance comprises a dye organic substance with benzene ring structure; the dye organic substance comprises one or more of basic blue 7, solvent blue 38, methylene blue and reactive blue 21, and further comprises basic blue 7; the cationic surfactant comprises one or more of cetyltrimethylammonium bromide and cetyltrimethylammonium chloride, and further comprises cetyltrimethylammonium bromide; the source of the basic substance comprises one or more of ammonia, sodium hydroxide and sodium carbonate, and further comprises ammonia.

[0046] In the present application, the preparation process of the basic organic solution comprises: adding the organic substance, the cationic surfactant and the basic substance into water to prepare the basic organic solution; in some embodiments, the basic substance can be added in the form of lye, for example, ammonia is used in the form of lye to prepare the basic organic solution and to achieve a specific concentration.

[0047] In the present application, the concentration of fluosilicic acid in the fluosilicic acid solution is 0.1-0.7 mol / L, and further is 0.4-0.5 mol / L.

[0048] In the alkaline organic solution of the present invention, the concentration of the organic substance is 1-10 g / L, more preferably 5-8 g / L; the concentration of the cationic surfactant is 1-10 g / L, more preferably 3-6 g / L; and the concentration of the alkaline substance is 0.2-2 mol / L, more preferably 0.7-1.0 mol / L.

[0049] In this invention, the volume ratio of the fluorosilicic acid solution to the alkaline organic solution is 1:3-1:8, more specifically 1:3-1:5; the molar ratio of fluorosilicic acid to the alkaline substance in the fluorosilicic acid solution is 1:4-1:10, more specifically 1:6-1:10.

[0050] In this invention, the mixing temperature is 50-100℃, more specifically 75-95℃; the mixing time is 2-8 hours, more specifically 3-5 hours. The process of mixing the fluorosilicic acid solution and the alkaline organic solution specifically includes: heating the alkaline organic solution to 50-100℃ (more specifically 75-85℃), adding the fluorosilicic acid solution to the alkaline organic solution; stirring at 50-100℃ (more specifically 85-95℃) for 2-8 hours (more specifically 3-5 hours), with a stirring speed of 100-600 rpm. Specifically, after preheating the alkaline organic solution, the fluorosilicic acid solution is added to the alkaline organic solution at a rate of 1-5 mL / min.

[0051] S2, the reaction liquid is separated into solid and liquid phases to obtain a solid separator; the solid separator is carbonized to obtain F / N-aCMs@SiO2 material, wherein the F / N-aCMs@SiO2 material is a metal-free catalyst material and does not contain any metal elements.

[0052] In this invention, the carbonization is carried out under the protection of an inert atmosphere; the inert atmosphere includes one or more of argon, nitrogen, and helium.

[0053] In this invention, the carbonization temperature is 400-700℃ (more specifically 400-600℃), the carbonization holding time is 30-180min (more specifically 40-80min), the carbonization heating rate is 2-8℃ / min, and the inert atmosphere flow rate during the carbonization process is 5-30L / min (more specifically 20-30L / min).

[0054] In this invention, step S2 further includes: drying the solid separation before carbonization; the drying process includes freeze drying, oven drying, etc.

[0055] As a supplementary explanation to the present invention, in the preparation method of the metal-free catalytic material of the present invention, when the fluorosilicic acid solution is added to the organic alkaline solution, the fluorosilate ions (SiF6)... 2- It will react with the OH- ions therein and transform into silicon dioxide, as shown in the following reaction equation:

[0056] 2H + +SiF6 2- +6OH - =SiO2 + 6F - +4H2O

[0057] During this process, cationic surfactants can integrate organic matter into the micelles during micelle formation, and the organic matter can also adhere to the silica surface.

[0058] During the carbonization process, on the one hand, the cationic surfactant decomposes and carbonizes to form a mesoporous structure; on the other hand, organic matter remains on the SiO2 surface through the fixation of silica and carbonizes under oxygen-free conditions at high temperatures to form a fluorine-nitrogen co-doped carbon (F / N-aCMs) structure, ultimately forming an F / N-aCMs@SiO2 material. Here, F / N-aCMs are the key photocatalytic active sites, while the mesoporous SiO2 serves as the supporting substrate and provides a high specific surface area.

[0059] The metal-free catalytic material preparation method of the present invention yields F / N-aCMs@SiO2 metal-free catalytic material, which can directly realize the catalytic oxidation process of aldehydes without the need for any metal doping, and has a high catalytic conversion rate, even achieving near-complete catalysis, avoiding the use of precious metal catalysts, organic solvents, strong oxidizing substances, etc.

[0060] The present invention also provides a metal-free catalytic material, comprising: prepared by any of the preparation methods described above.

[0061] The present invention also provides an application of any of the metal-free catalytic materials described above in the photocatalysis of aldehydes.

[0062] The application of the photocatalytic aldehyde substance specifically includes: mixing the metal-free catalytic material with the aldehyde substance (aldehyde reaction substrate) and then carrying out a photocatalytic reaction to convert the aldehyde substance into a carboxylic acid substance; the application or the photocatalytic reaction is carried out under illumination, which can be sunlight simulated by a xenon lamp or LED lamp.

[0063] In this invention, the aldehydes include one or more of benzaldehyde, cinnamaldehyde, p-bromobenzaldehyde, p-methoxybenzaldehyde, p-methylbenzaldehyde, p-chlorobenzaldehyde, and o-methoxybenzaldehyde, which are converted into corresponding carboxylic acids, such as benzoic acid, cinnamic acid, p-bromobenzaldehyde, p-methoxybenzaldehyde, p-methylbenzaldehyde, p-chlorobenzaldehyde, and o-methoxybenzaldehyde, after a catalytic reaction. The aldehydes are further selected from one or more of benzaldehyde, cinnamaldehyde, p-methylbenzaldehyde, and p-chlorobenzaldehyde, preferably cinnamaldehyde, thereby achieving a 99% carboxylic acid conversion rate.

[0064] In this invention, the mass ratio of the metal-free catalytic material to the aldehyde is 1:25-1:100, more preferably 1:25-1:45, and most preferably 1:28-1:40; the photocatalytic duration is 3-12h, more preferably 3-8h, more preferably 3-6h, and can also be 4-6h, 5-12h, 6-12h, or 6-8h.

[0065] In this invention, the reaction temperature of the photocatalysis is 20-60℃, and more specifically 20-30℃; the stirring rate of the photocatalysis is 100-600 rpm; the photocatalysis process in this invention simulates natural light, specifically using a xenon lamp with a power of 200-400W.

[0066] As a supplementary explanation to the present invention, the surface of the F / N-aCMs@SiO2 material formed by carbonization has abundant and special F / N-aCMs structures. The F / N-aCMs structures can promote the generation of free radicals under light conditions during the aldehyde reaction, thereby initiating the catalytic oxidation process of aldehydes.

[0067] The following are specific examples of the present invention:

[0068] Example 1

[0069] I. The preparation steps of metal-free catalytic materials are as follows:

[0070] S1. Take 1.28g of Basic Blue 7, 0.91g of cetyltrimethylammonium bromide, and 13mL of ammonia (molar concentration approximately 13.38mol / L) and add them to 187mL of deionized water to prepare an alkaline organic solution, and preheat it to 80℃.

[0071] Take 8 mL of fluorosilicic acid stock solution (molar concentration of approximately 2.78 mol / L) and add it to 42 mL of deionized water to prepare a 0.44 mol / L fluorosilicic acid solution.

[0072] The above fluorosilicic acid solution was added to the preheated alkaline organic solution at a rate of 2 mL / min, and the reaction was carried out at a stirring rate of 500 rpm and a reaction temperature of 90 °C for 4 h to obtain the reaction solution.

[0073] S2. After filtering the reaction solution, the solid precipitate was collected and dried in an oven at 80°C for 12 hours.

[0074] Then, the precipitate was placed in a crucible and put into a tube furnace. Argon gas was continuously introduced at a rate of 25 L / min, the heating rate was 4 °C / min, the carbonization temperature was 500 °C, and the carbonization holding time was 1 h, to obtain the metal-free catalyst material (F / N-aCMs@SiO2 material).

[0075] See Figure 1 As shown, in this embodiment, the carbonized sample (without metal catalyst) is in the form of spherical particles, and the sample has a distinct mesoporous structure.

[0076] See Figure 2 a and Figure 2 As shown in b, in this embodiment, the specific surface area of ​​the carbonized sample (without metal catalyst) is 439.9 m². 2 / g, with a mesopore size of 2.7nm.

[0077] See Figure 3 As shown, the TEM-EDS results reveal that the C, N, and F elements in the carbonized sample (without metal catalyst) are uniformly distributed in the sample, without any obvious aggregation.

[0078] See Figure 4 a and Figure 4 As shown in b. Figure 4 a shows the N1s spectra of F / N-aCMs@SiO2 material and F / N-aCMs material after etching SiO2 in F / N-aCMs@SiO2 material. From the spectra, it can be found that the N in the material exists in pyrrole nitrogen, pyridine nitrogen and graphitic nitrogen, which indicates that the N element exists in the carbon structure. Figure 4 b shows the F1s spectra of F / N-aCMs@SiO2 material and F / N-aCMs material after etching SiO2 from F / N-aCMs@SiO2 material. Comparison reveals the presence of CF bonds in the carbon structure, indicating the presence of F element. These results collectively demonstrate the presence of N and F elements in the F / N-aCMs structure.

[0079] Example 2

[0080] Take 3g of benzaldehyde and place it in a 20mL volumetric flask. Add 0.03g of the metal-free catalyst from Example 1. Stir at 300rpm and at 25℃. React for 6h under a 300W xenon lamp.

[0081] Example 3

[0082] Take 3g of benzaldehyde and place it in a 20mL volumetric flask. Add 0.045g of the metal-free catalyst from Example 1. Stir at 300rpm and at 25℃. React for 6h under a 300W xenon lamp.

[0083] Example 4

[0084] Take 3g of benzaldehyde and place it in a 20mL volumetric flask. Add 0.06g of the metal-free catalyst from Example 1. Stir at 300rpm and at 25℃. React for 6h under a 300W xenon lamp.

[0085] Example 5

[0086] Take 3g of benzaldehyde and place it in a 20mL volumetric flask. Add 0.075g of the metal-free catalyst from Example 1. Stir at 300rpm and at 25℃. React for 6h under a 300W xenon lamp.

[0087] Example 6

[0088] Take 3g of benzaldehyde and place it in a 20mL volumetric flask. Add 0.09g of the metal-free catalyst from Example 1. Stir at 300rpm and at 25℃. React for 6h under a 300W xenon lamp.

[0089] Example 7

[0090] Take 3g of benzaldehyde and place it in a 20mL volumetric flask. Add 0.105g of the metal-free catalyst from Example 1. Stir at 300rpm and at 25℃. React for 6h under a 300W xenon lamp.

[0091] Analysis Example 1

[0092] The conversion rates of benzaldehyde to benzoic acid in Examples 2-7 were determined; see [link to relevant documentation]. Figure 5 As shown, in Example 1, when the mass ratio of the metal-free catalyst to the benzaldehyde substrate was 1:100-1:28, the material could be photocatalyzed to benzoic acid. The conversion rate increased with the increase of the amount of metal-free catalyst. In Examples 5 and 6, the conversion rate reached 94%. In Example 7, the conversion rate reached 95%.

[0093] Example 8

[0094] Take 3g of benzaldehyde and place it in a 20mL volumetric flask. Add 0.075g of the metal-free catalyst from Example 1. Stir at 300rpm and at 25℃. React for 1h under a 300W xenon lamp.

[0095] Example 9

[0096] Take 3g of benzaldehyde and place it in a 20mL volumetric flask. Add 0.075g of the metal-free catalyst from Example 1. Stir at 300rpm and at 25℃. React for 2 hours under a 300W xenon lamp.

[0097] Example 10

[0098] Take 3g of benzaldehyde and place it in a 20mL volumetric flask. Add 0.075g of the metal-free catalyst from Example 1. Stir at 300rpm and at 25℃. React for 3h under a 300W xenon lamp.

[0099] Example 11

[0100] Take 3g of benzaldehyde and place it in a 20mL volumetric flask. Add 0.075g of the metal-free catalyst from Example 1. Stir at 300rpm and at 25℃. React for 4h under a 300W xenon lamp.

[0101] Example 12

[0102] Take 3g of benzaldehyde and place it in a 20mL volumetric flask. Add 0.075g of the metal-free catalyst from Example 1. Stir at 300rpm and at 25℃. React for 6h under a 300W xenon lamp.

[0103] Analysis example 2

[0104] The conversion rate of benzaldehyde to benzoic acid after the reaction was determined in Examples 8-12; see [link to relevant documentation]. Figure 6 As shown, a relatively high conversion rate can be achieved when the reaction time is above 3 hours. The conversion rates of Examples 10, 11 and 12 are 92%, 94% and 96%, respectively.

[0105] Example 13

[0106] Take 3g of benzaldehyde and place it in a 20mL volumetric flask. Add 0.075g of the metal-free catalyst from Example 1. Stir at 300rpm and at 25℃. React for 6h under a 300W xenon lamp.

[0107] Example 14

[0108] Take 3g of p-methoxybenzaldehyde and place it in a 20mL volumetric flask. Add 0.075g of the metal-free catalyst from Example 1. Stir at 300rpm and at 25℃. React for 6h under a 300W xenon lamp.

[0109] Example 15

[0110] Take 3g of p-methylbenzaldehyde and place it in a 20mL volumetric flask. Add 0.075g of the metal-free catalyst from Example 1. Stir at 300rpm and at 25℃. React for 6h under a 300W xenon lamp.

[0111] Example 16

[0112] Take 3g of p-chlorobenzaldehyde and place it in a 20mL volumetric flask. Add 0.075g of the metal-free catalyst from Example 1. Stir at 300rpm and at 25℃. React for 6h under a 300W xenon lamp.

[0113] Example 17

[0114] Take 3g of o-methoxybenzaldehyde and place it in a 20mL volumetric flask. Add 0.075g of the metal-free catalyst from Example 1. Stir at 300rpm and at 25℃. React for 6h under a 300W xenon lamp.

[0115] Example 18

[0116] Take 3g of p-bromobenzaldehyde and place it in a 20mL volumetric flask. Add 0.075g of the metal-free catalyst from Example 1. Stir at 300rpm and at 25℃. React for 6h under a 300W xenon lamp.

[0117] Example 19

[0118] Take 3g of cinnamaldehyde and place it in a 20mL volumetric flask. Add 0.075g of the metal-free catalyst from Example 1. Stir at 300rpm and at 25℃. React for 6h under a 300W xenon lamp.

[0119] Analysis Example 3

[0120] The conversion rates of aldehydes after the reaction were determined in Examples 13-19; see [link to relevant documentation]. Figure 7 As shown, the metal-free catalytic material in Example 1 can catalytically oxidize aldehyde substrates such as benzaldehyde, p-methoxybenzaldehyde, p-methylbenzaldehyde, p-chlorobenzaldehyde, o-methoxybenzaldehyde, p-bromobenzaldehyde, and cinnamic acid to form the corresponding carboxylic acids (benzoic acid, p-methoxybenzaldehyde, p-methylbenzaldehyde, p-chlorobenzaldehyde, o-methoxybenzaldehyde, p-bromobenzaldehyde, and cinnamic acid) and achieve a high conversion rate; after photocatalysis based on cinnamic acid, the conversion rate even reaches 99%.

[0121] Comparative Example 1

[0122] I. Preparation of catalytic materials:

[0123] Compared to Example 1, this comparative example does not include cetyltrimethylammonium bromide, while other conditions remain unchanged.

[0124] See Figure 8 As shown in the comparative example, the carbonized sample is composed of nano-sized aggregated particles and has no mesoporous structure.

[0125] See Figure 9 As shown in the nitrogen adsorption-desorption curve ( Figure 9 a) It can be seen that in this comparative example, the specific surface area of ​​the carbonized sample is 110.4 m². 2 / g, pore size distribution map ( Figure 9 b) It can be seen that in this comparative example, the carbonized sample does not have a mesoporous structure.

[0126] II. Compared with Example 5, this comparative example only changed the catalyst material to the material prepared in this comparative example, while keeping other conditions unchanged.

[0127] The conversion rate of this comparative example was 81%, which was much lower than that of Example 5. This was mainly because CTAB was added during the synthesis of the catalyst material in Example 1, which enabled the synthesized catalyst material to have a mesoporous structure and a larger specific surface area. This provided more active sites and reaction area. However, the catalyst material in this comparative example did not have a mesoporous structure and had a smaller specific surface area, which also resulted in a lower conversion rate under the same conditions.

[0128] Comparative Example 2

[0129] I. Preparation of catalytic materials:

[0130] Compared to Example 1, this comparative example uses tetraethyl orthosilicate (TEOS) as the silicon source. Specifically, 4.48 g of TEOS is added to 45 mL of ethanol (total volume approximately 50 mL, Si concentration approximately 0.43 mol / L) to replace the fluorosilicic acid solution; other conditions remain unchanged.

[0131] See Figure 10 As shown, in this comparative example, the carbonized sample (without metal catalyst) is in the form of spherical particles, and the sample has a distinct mesoporous structure.

[0132] The material obtained after carbonization in this comparative example is denoted as N-aCMs@SiO2 material. Figure 11a shows the N1s spectra of N-aCMs@SiO2 material and N-aCMs material after etching SiO2 in N-aCMs@SiO2 material. From the spectra, it can be found that N in the material exists in pyrrole nitrogen, pyridine nitrogen and graphitic nitrogen, which indicates that N element exists in the carbon structure of N-aCMs@SiO2 material.

[0133] Figure 11 b shows the F1s spectra of N-aCMs@SiO2 material and N-aCMs material after etching SiO2 in N-aCMs@SiO2 material. By comparison, it can be found that there is no F element signal in the carbon structure, which indicates that there is no F element in the carbon structure.

[0134] The above results collectively indicate that nitrogen (N) is present in the N-aCMs structure, but sulfur (F) is absent. This suggests that the difference between the materials obtained in Comparative Example 2 and Example 1 lies in the presence of both N and F elements in the carbon structure of Example 1, while the carbon structure of Comparative Example 2 contains N but lacks F. This is primarily because Example 1 used H₂SiF₆ as a silicon source, allowing F to be introduced into the carbon structure during synthesis, while Comparative Example 2 used TEOS as a silicon source, thus lacking an F source and therefore unable to introduce F into the carbon structure.

[0135] II. Compared with Example 10, this comparative example only changed the catalyst material to the material prepared in this comparative example, while keeping other conditions unchanged.

[0136] The conversion rate of this comparative example was 82%, which was significantly lower than that of Example 10. This is mainly because, compared to the single N-doped carbon structure in Comparative Example 2, the F and N co-doped carbon structure in Example 1 can further adjust the electron-hole separation degree of the carbon structure.

[0137] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for preparing a metal-free catalytic material, characterized in that, Including the following steps: S1, Mix fluorosilicic acid solution and alkaline organic solution to obtain reaction solution; The alkaline organic solution comprises organic matter, a template agent, and an alkaline substance; the template agent comprises a cationic surfactant. S2, the reaction liquid is separated into solid and liquid phases to obtain a solid separator; the solid separator is then carbonized to obtain F / N-aCMs@SiO2 material, wherein the F / N-aCMs@SiO2 material is a metal-free catalyst.

2. The method for preparing the metal-free catalytic material according to claim 1, characterized in that, The organic substance includes dye organic compounds with a benzene ring structure; the dye organic compounds include one or more of Basic Blue 7, Solvent Blue 38, Methylene Blue, and Reactive Blue 21; The cationic surfactant includes one or more of hexadecyltrimethylammonium bromide and hexadecyltrimethylammonium chloride; The alkaline substance includes one or more of ammonia, sodium hydroxide, and sodium carbonate.

3. The method for preparing the metal-free catalytic material according to claim 1, characterized in that, The concentration of fluorosilicic acid in the fluorosilicic acid solution is 0.1-0.7 mol / L; In the alkaline organic solution, the concentration of the organic substance is 1-10 g / L, the concentration of the cationic surfactant is 1-10 g / L, and the concentration of the alkaline substance is 0.2-2 mol / L. The volume ratio of the fluorosilicic acid solution to the alkaline organic solution is 1:3 to 1:8; The molar ratio of the fluorosilicic acid to the alkaline substance is 1:4 to 1:

10.

4. The method for preparing the metal-free catalytic material according to claim 1, characterized in that, In step S1, the mixing temperature is 50-100℃ and the mixing time is 2-8h.

5. The method for preparing the metal-free catalytic material according to claim 1, characterized in that, The carbonization is carried out under an inert atmosphere; the carbonization temperature is 400-700℃, and the carbonization time is 30-180min.

6. The method for preparing the metal-free catalytic material according to claim 1, characterized in that, Step S2 further includes drying the solid separation material before carbonization.

7. A metal-free catalytic material, characterized in that, include: It is prepared by the preparation method described in any one of claims 1-6.

8. The application of the metal-free catalytic material as described in claim 7 in the photocatalysis of aldehydes.

9. The application according to claim 8, characterized in that, The aldehydes include one or more of benzaldehyde, cinnamaldehyde, p-bromobenzaldehyde, p-methoxybenzaldehyde, p-methylbenzaldehyde, p-chlorobenzaldehyde, and o-methoxybenzaldehyde.

10. The application according to claim 8 or 9, characterized in that, The mass ratio of the metal-free catalytic material to the aldehyde is 1:25-1:100; the photocatalysis duration is 3-12 hours.

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