Synthesis method and application of BiVO4 / BiOCl photocatalyst

Abstract

The invention discloses a synthesis method and application of a BiVO4 / BiOCl photocatalyst, and belongs to the technical field of catalysts. According to the method, bismuth nitrate, NH4VO3 and NH4Cl are taken as raw materials, the raw materials are fully mixed through grinding, meanwhile, the reaction activity of the raw materials is improved, then the ground materials are roasted, the photocatalyst BiVO4 / BiOCl is synthesized in one step, the synthesis steps are simple, meanwhile, the problem that an acidic reagent or an alkaline reagent needs to be used in a traditional preparation method is solved, and the method is suitable for industrial production. And by controlling the mass ratio of NH4VO3 to NH4Cl, the BiVO4 / BiOCl photocatalyst with high selectivity and high conversion rate for catalytic oxidation of amine compounds is obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and particularly relates to a synthesis method and application of a BiVO4 / BiOCl photocatalyst. Background Art

[0002] Due to reasons such as the daily and seasonal variations and uneven distribution of solar energy, there are problems such as low light energy utilization efficiency, difficult storage and conversion of solar energy. Inspired by the photosynthesis of green plants in nature, people began to explore how to effectively utilize solar energy through artificial means. Photocatalysis technology is a technology that uses solar energy to promote reactions at room temperature, which can solve the problems of solar energy conversion and storage at the same time. This technology can not only be used for the production of clean fuels, but also be widely applied to aspects such as pollutant degradation, CO2 reduction, and sterilization and disinfection.

[0003] Since Fujishima et al. discovered that TiO2 single crystal electrodes can achieve the decomposition of water under ultraviolet light, various photocatalysts have emerged in an endless stream, mainly existing as metal oxides, metal sulfides, metal phosphides, perovskites, organic hybrid materials, conjugated polymers, etc. Each type of photocatalyst shows its own capabilities, constituting a colorful photocatalytic world. Among them, bismuth-based materials are rich in reserves, non-toxic, and resistant to photocorrosion. In particular, bismuth oxychloride (BiOCl) also has a special layered structure, and in the crystal, the 2+ [Bi2O2] 2- layer is sandwiched between two 2+ [Cl2] 2-The electrostatic field of the layer can induce the separation of photo-generated electron-hole (e-h) pairs, which contributes to good photocatalytic activity. However, the band gap of BiOCl is 3.4 eV, resulting in low visible light utilization and high photo-generated electron-hole recombination efficiency, which limits its photocatalytic performance. Therefore, BiOCl needs to be modified to improve its photocatalytic performance. Bismuth vanadate (BiVO4) has become a better choice for modifying BiOCl due to its suitable band gap (2.4 eV) and good visible light responsiveness. However, most of the preparation methods of BiVO4 / BiOCl composites reported in the existing literature are solvothermal methods, involving harsh reaction conditions such as high temperature and high pressure, and even involving long reaction times, complex preparation processes, and the use of reagents such as strong acids and strong bases. For example, Patent CN115254151A discloses a core-shell structure BiVO4@BiOCl heterojunction and its preparation method and application, in which the synthesis of icosahedral monoclinic BiVO4 uses a hydrothermal reaction with a long reaction time, and the core-shell structure BiVO4@BiOCl heterojunction is prepared by a two-step method. Compared with the one-step synthesis, the product yield is reduced, and acidic solvents such as dilute hydrochloric acid and dilute nitric acid are used in the synthesis process, which does not conform to the green synthesis route. Another example is Patent CN1177339610A, which discloses a BiOCl-modified BiVO4 composite photocatalyst and its preparation method. In this patent, the preparation process of the BiOCl-modified BiVO4 composite photocatalyst requires adjusting the pH value and uses strong bases such as sodium hydroxide. The preparation process is complex, and there is product loss during the suction filtration process.

[0004] Therefore, there is an urgent need for a preparation method of BiVO4 / BiOCl composites with simple preparation method and low production cost. Summary of the Invention

[0005] To solve the above technical problems, the present invention proposes a synthesis method and application of a BiVO4 / BiOCl photocatalyst.

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

[0007] The present invention provides a synthesis method of a BiVO4 / BiOCl photocatalyst, comprising the following steps:

[0008] Mix bismuth nitrate and mixed ammonium salts, then grind and calcine to obtain the BiVO4 / BiOCl photocatalyst;

[0009] The mixed ammonium salts are NH4VO3 and NH4Cl; the mass ratio of NH4VO3 to NH4Cl is 1∶(1 - 3).

[0010] Technical principle: The present invention uses bismuth nitrate, NH4VO3 and NH4Cl as raw materials. First, the raw materials are fully mixed by grinding, and at the same time, the reaction activity of each raw material is improved. Then, the ground material is calcined to synthesize the photocatalyst BiVO4 / BiOCl in one step. The synthesis steps are simple, and at the same time, the problem of using acidic or alkaline reagents in traditional preparation methods is avoided. By controlling the mass ratio of NH4VO3 and NH4Cl, a BiVO4 / BiOCl photocatalyst with high selectivity and high conversion rate for catalytic oxidation of amine compounds is obtained.

[0011] Preferably, the mass ratio of bismuth nitrate to the mixed amine salt is 4:1.

[0012] Preferably, the grinding speed is 450 r / min, the grinding time is 15 min, and the ball-to-material ratio is 4:1.

[0013] Preferably, the calcination temperature is 500 °C, the calcination time is 6 h, and the calcination atmosphere is an air atmosphere.

[0014] Preferably, the heating rate of the calcination is a programmed heating rate.

[0015] Preferably, the programmed heating is specifically as follows: First, heat up to 300 °C at a heating rate of 10 °C / min and hold for 30 min, then heat up to 500 °C at a heating rate of 2.5 °C / min and hold for 6 h.

[0016] Preferably, the mass ratio of NH4VO3 to NH4Cl is 1:1.

[0017] The present invention provides the BiVO4 / BiOCl photocatalyst obtained by the synthesis method described in the above technical solution.

[0018] The present invention also provides the application of the BiVO4 / BiOCl photocatalyst described in the above technical solution in the catalytic oxidation of amine compounds.

[0019] Preferably, the amine compound is selected from one of 2-furfurylamine, 4-methylbenzylamine, 4-methoxybenzylamine, 4-chlorobenzylamine, 3-methoxybenzylamine, 4-fluorobenzylamine, 4-(trifluoromethyl)-benzylamine, 2-methoxybenzylamine, 2-aminomethylpyridine, and thiophene-2-methylamine.

[0020] Compared with the prior art, the present invention has the following advantages and technical effects:

[0021] The present invention synthesizes the photocatalyst BiVO4 / BiOCl in one step by simple grinding and roasting. The synthesis steps are simple, avoiding the waste of products in multiple synthesis processes. At the same time, it avoids the problem of using acidic or alkaline reagents in traditional preparation methods. No strong acids, strong bases or corrosive solvents are used in the synthesis process, meeting the requirements of green synthesis.

[0022] The synthesis method provided by the present invention has a short preparation time, greatly saving the preparation time of the catalyst and facilitating the acceleration of the reaction process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0024] Figure 1 is the process flow chart of the synthesis method of the BiVO4 / BiOCl photocatalyst provided by the present invention;

[0025] Figure 2 is the infrared spectrum of the photocatalysts prepared in Examples 1-2 and Comparative Examples 1-2;

[0026] Figure 3 is the XRD pattern of the photocatalysts prepared in Examples 1-2 and Comparative Examples 1-2;

[0027] Figure 4 is the SEM image of the photocatalysts prepared in Examples 1-2 and Comparative Examples 1-2, where a is BiVO4, b is BiVO4-Cl(1:3), c is BiVO4-Cl(1:1), d is BiVO4-Cl(3:1), and e is BiOCl;

[0028] Figure 5 is the ultraviolet-visible absorption spectrum of the photocatalysts prepared in Examples 1-2 and Comparative Examples 1-2;

[0029] Figure 6 is the fluorescence spectrum of the photocatalysts prepared in Examples 1-2 and Comparative Examples 1-2;

[0030] Figure 7 is the XPS spectrum of the photocatalysts prepared in Example 1 and Comparative Example 2, where a is the full spectrum, b is Bi 4f, c is Cl 2p, d is O1s, and e is V 2p;

[0031] Figure 8 is the nitrogen adsorption-desorption curve (a) and pore size distribution diagram (b) of the photocatalysts prepared in Examples 1-2 and Comparative Examples 1-2. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0033] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0034] An embodiment of the present invention provides a synthesis method of a BiVO4 / BiOCl photocatalyst, including the following steps:

[0035] Mix bismuth nitrate and a mixed amine salt, then grind and then calcine to obtain the BiVO4 / BiOCl photocatalyst;

[0036] The mixed amine salt is NH4VO3 and NH4Cl; the mass ratio of NH4VO3 to NH4Cl is 1∶(1 - 3).

[0037] In a preferred embodiment, the mass ratio of bismuth nitrate to the mixed amine salt is 4∶1.

[0038] In a preferred embodiment, the bismuth nitrate is Bi(NO3)3·5H2O. The bismuth nitrate in the present invention is used to provide a bismuth source.

[0039] In a preferred embodiment, the grinding speed is 450 r / min, the grinding time is 15 min, and the ball-to-material ratio is 4:1 (mass ratio). The present invention makes the raw materials fully mixed through grinding, and at the same time improves the reaction activity of the raw materials, which is beneficial to shortening the time required for the subsequent calcination process.

[0040] In a preferred embodiment, the calcination temperature is 500 °C, the calcination time is 6 h, and the calcination atmosphere is an air atmosphere. The present invention successfully synthesizes the BiVO4 / BiOCl photocatalyst by calcining at the above temperature.

[0041] In a preferred embodiment, the heating method of the calcination is programmed heating.

[0042] In a preferred embodiment, the programmed heating is specifically as follows: first, heat up to 300 °C at a heating rate of 10 °C / min, hold for 30 min, and then heat up to 500 °C at a heating rate of 2.5 °C / min and hold for 6 h. The present invention is beneficial to controlling the component dispersion degree and the carrier pore structure by adopting the programmed heating method for calcination.

[0043] In a preferred embodiment, the mass ratio of NH4VO3 to NH4Cl is 1: (1-3), and more preferably 1: 1. The present invention controls the ratio of BiVO4 to BiOCl in the obtained photocatalyst by controlling the mass ratio of NH4VO3 to NH4Cl. Controlling the mass ratio of NH4VO3 to NH4Cl within the above range is conducive to obtaining a photocatalyst with high conversion rate and selectivity.

[0044] The present invention provides a BiVO4 / BiOCl photocatalyst obtained by the synthesis method described in the above technical scheme.

[0045] The present invention also provides the use of the BiVO4 / BiOCl photocatalyst described in the above technical solution in catalytic oxidation of amine compounds.

[0046] In a preferred embodiment, the amine compound is selected from one of benzylamine, 2-furylamine, 4-methylbenzylamine, 4-methoxybenzylamine, 4-chlorobenzylamine, 3-methoxybenzylamine, 4-fluorobenzylamine, 4-(trifluoromethyl)-benzylamine, 2-methoxybenzylamine, 2-aminomethylpyridine and thiophene-2-methylamine.

[0047] The room temperature in the embodiments of the present invention refers to "25±2°C".

[0048] Unless otherwise specified, the raw materials in the examples of the present invention were purchased from commercial sources.

[0049] Example 1

[0050] 2.07g Bi(NO3)3·5H2O and 0.5g mixed amine salt were added to a mortar and ground at a speed of 450r / min for 15min. The grinding ball-to-material ratio was 4:1 (mass ratio). The mixed amine salt was composed of NH4VO3 and NH4Cl in a mass ratio of 1:1. The ground materials were then loaded into a porcelain boat, which was placed in a muffle furnace. Under an air atmosphere, the temperature was first increased to 300°C at a heating rate of 10°C / min and kept warm for 30min. The temperature was then increased to 500°C at a heating rate of 2.5°C / min and kept warm for 6h. The product was collected to obtain a yellow block powder, which was the BiVO4 / BiOCl photocatalyst, recorded as BiVO4-Cl (1:1).

[0051] Example 2

[0052] The difference from Example 1 is that the mixed amine salt is composed of NH4VO3 and NH4Cl in a mass ratio of 1:3, and the rest is the same as Example 1. The obtained BiVO4 / BiOCl photocatalyst is recorded as BiVO4-Cl (1:3).

[0053] Comparative Example 1

[0054] It is different from Example 1 in that the mixed amine salt is composed of NH4VO3 and NH4Cl in a mass ratio of 3:1, and the others are the same as in Example 1. The obtained BiVO4 / BiOCl photocatalyst is denoted as BiVO4-Cl(3:1).

[0055] Comparative Example 2

[0056] Add 2.07 g of Bi(NO3)3·5H2O and 0.5 g of NH4VO3 into a mortar, grind at a speed of 450 r / min for 15 min, and the ball-to-material ratio for grinding is 4:1. Then put the ground material into a porcelain boat, place the porcelain boat in a muffle furnace, under an air atmosphere, first heat it to 300 °C at a heating rate of 10 °C / min, keep it warm for 30 min, and then heat it to 500 °C at a heating rate of 2.5 °C / min and keep it warm for 6 h. Collect the product to obtain the BiVO4 photocatalyst.

[0057] Figure 2 It is the infrared spectra of the photocatalysts prepared in Examples 1-2 and Comparative Examples 1-2. As can be Figure 2 seen, the absorption peaks of different samples in the infrared spectrum are different, indicating that the addition of NH4Cl and the change of its ratio have a certain influence on the structure and functional groups of the BiVO4 / BiOCl photocatalyst. The spectrum of the BiVO4 photocatalyst (Comparative Example 2) shows the characteristic absorption peaks of BiVO4, such as the V-O stretching vibration at 500 - 1000 cm -1 and the O-H vibration at 3000 - 3500 cm -1 (possibly from surface adsorbed water or hydroxyl groups). Compared with BiVO4, for BiVO4-Cl(1:3), BiVO4-Cl(1:1), and BiVO4-Cl(3:1) after doping with NH4Cl, the peak positions at 500 - 1000 cm -1 change, which may be related to the formation of BiOCl. In addition, with the increase of the NH4Cl content, the intensities of some peaks in the spectrum change, indicating that the proportion of the BiOCl phase affects the structural characteristics of the catalyst. As the ratio of NH4Cl changes from 1:3 to 3:1, the intensities of the BiOCl-related absorption peaks in the spectrum change to varying degrees, indicating different amounts of BiOCl generated, which may affect the light absorption characteristics and catalytic activity of the photocatalyst. Therefore, the addition of NH4Cl and the adjustment of its ratio affect the structure of the BiVO4 / BiOCl photocatalyst, making it have different photocatalytic performances.

[0058] Figure 3 It is the XRD patterns of the photocatalysts prepared in Examples 1-2 and Comparative Examples 1-2. As can be Figure 3It can be seen that the diffraction peaks of different samples in the XRD pattern vary, indicating that the addition of NH4Cl and its proportion have an impact on the crystal structure of the BiVO4 / BiOCl photocatalyst. The diffraction peaks of the BiVO4 sample (Comparative Example 2) mainly match those of tetragonal BiVO4 (JCPDS No.14-0688), indicating that it is mainly composed of a single BiVO4 phase. In the BiVO4-Cl(1:3), BiVO4-Cl(1:1), and BiVO4-Cl(3:1) samples, in addition to the characteristic peaks of BiVO4, new diffraction peaks were also observed, indicating the formation of the BiOCl (JCPDSNo.06-0249) phase. With the change of the NH4Cl proportion, the diffraction peak intensities of the BiOCl phase are different, indicating that the content of BiOCl changes. Especially when the NH4Cl proportion is relatively high (such as BiVO4-Cl(3:1)), the diffraction peak intensity of the BiOCl phase is more obvious, indicating an increase in its content. Therefore, the addition of NH4Cl promotes the formation of the BiOCl phase and changes the phase composition of the BiVO4 / BiOCl photocatalyst, which may have an important impact on its photocatalytic performance.

[0059] Figure 4 SEM images of the photocatalysts prepared in Examples 1-2 and Comparative Examples 1-2, where a is BiVO4, b is BiVO4-Cl(1:3), c is BiVO4-Cl(1:1), d is BiVO4-Cl(3:1), and e is BiOCl. Figure 4 It can be seen that there are significant differences in the microscopic morphologies of different samples, indicating that the addition of NH4Cl and its proportion have a great impact on the morphological structure of the BiVO4 / BiOCl photocatalyst. BiVO4 ( Figure 4 a) exhibits an irregular agglomerated blocky morphology with a relatively rough surface, which may be formed by particle accumulation. BiVO4-Cl(1:3) ( Figure 4 b) shows a relatively loose flaky structure, indicating that the introduction of the BiOCl phase changes the morphology of the material. BiVO4-Cl(1:1) ( Figure 4 c) shows a morphology with partial regular flakes and blocks coexisting, indicating that a good composite structure is formed between BiVO4 and BiOCl. BiVO4-Cl(3:1) ( Figure 4 d) has a morphology similar to that of BiVO4-Cl(1:3), but the flaky structure is more obvious, indicating that a higher proportion of NH4Cl promotes the formation of the BiOCl lamellar structure. In addition, the lamellar structure of BiOCl ( Figure 4e) More regular, further verifying the influence of the NH4Cl ratio on the product morphology. Generally speaking, the addition of NH4Cl causes the transformation of BiVO4 from a blocky structure to a flaky structure, and with the increase of the NH4Cl ratio, the flaky structure gradually dominates. This morphological change may affect the specific surface area, light absorption ability and photocatalytic performance of the material.

[0060] Figure 5 UV-visible absorption spectra of the photocatalysts prepared in Examples 1-2 and Comparative Examples 1-2. As Figure 5 can be seen, there are obvious differences in the absorption characteristics of different samples in the UV-visible light region. Pure-phase BiVO4 (black curve) has a strong absorption ability in the visible light range, the absorption edge is about 540 nm, and the corresponding band gap is about 2.29 eV. With the introduction of BiOCl, the absorption spectra of BiVO4-Cl(1:3) (green curve), BiVO4-Cl(1:1) (blue curve) and BiVO4-Cl(3:1) (pink curve) change, and the absorption edges are all blue-shifted, indicating that the band gap of the composite material has increased. This may be due to the influence of the energy band structure of BiOCl on the electronic structure of BiVO4, resulting in an increase in the transition energy of photo-generated carriers. In addition, the absorption intensity of the BiVO4-Cl(1:3) sample is relatively low, indicating that a higher BiOCl ratio may lead to a decrease in the light absorption ability. Generally speaking, the band gap regulation effect of the BiVO4 / BiOCl composite material is significant, and the introduction of BiOCl affects the light absorption performance of BiVO4 to a certain extent.

[0061] Figure 6 Fluorescence spectra of the photocatalysts prepared in Examples 1-2 and Comparative Examples 1-2. As Figure 6 can be seen, strong emission peaks appear at about 450 nm in the fluorescence spectra of different photocatalysts, indicating that the main paths of photo-generated carrier recombination are similar. Compared with pure BiVO4 (black curve), the fluorescence intensity of the BiVO4-Cl composite material decreases, especially for BiVO4-Cl(1:3) (red curve) and BiVO4-Cl(3:1) (pink curve), and their fluorescence emissions are significantly weakened. This indicates that the introduction of BiOCl effectively reduces the recombination rate of photo-generated electron-hole pairs, which helps to improve the photocatalytic activity. In addition, the fluorescence intensity of the BiVO4-Cl(1:1) (blue curve) sample is between BiVO4 and other composite samples, indicating that the recombination degree of its photo-generated carriers is moderate. Therefore, it can be speculated that the formation of the BiVO4 / BiOCl heterojunction promotes the separation and migration of photo-generated carriers to a certain extent and improves the photocatalytic performance.

[0062] Figure 7XPS spectra of the photocatalysts prepared in Example 1 and Comparative Example 2, where a is the full spectrum, b is Bi 4f, c is Cl 2p, d is O 1s, and e is V 2p. It can be seen from Figure 7 that the full spectrum ( Figure 7 a) shows that the XPS peak positions of BiVO4-Cl and BiVO4 are basically the same, but an obvious Cl 2p signal appears in the BiVO4-Cl photocatalyst, confirming the successful introduction of the Cl element. The Bi 4f spectrum ( Figure 7 b) shows that the binding energies of Bi 4f 7 / 2 and Bi 4f 5 / 2 in BiVO4-Cl (164.78 eV and 159.48 eV) are slightly positively shifted compared with those in pure BiVO4 (164.38 eV and 159.08 eV), indicating that the introduction of Cl may change the chemical environment of Bi and enhance the role of the Bi-O bond. The Cl 2p spectrum ( Figure 7 c) further confirms the existence of Cl in BiVO4-Cl. The binding energies of Cl 2p 3 / 2 and Cl 2p 1 / 2 are located at 199.78 eV and 198.18 eV respectively, indicating that Cl may partially replace O2 - or form a Bi-O-Cl bond. The O 1s spectrum ( Figure 7 d) shows that the peak position of BiVO4-Cl (530.98 eV) is shifted compared with that of BiVO4 (529.68 eV), indicating that the introduction of Cl may affect the oxygen species in the material, increase the hydroxyl content, and thus may enhance the photocatalytic activity. The V 2p spectrum ( Figure 7 e) shows that the V 2p 3 / 2 (524.38 eV) and V 2p 1 / 2 (517.08 eV) in BiVO4-Cl are slightly shifted compared with those in BiVO4 (524.18 eV and 516.88 eV), which may be attributed to the change in the electronic environment of V caused by the introduction of Cl. In summary, XPS analysis shows that the successful doping of Cl affects the electronic structure of BiVO4 and may improve the photocatalytic performance.

[0063] Figure 8 N2 adsorption-desorption isotherm curves (a) and pore size distribution diagrams (b) of the photocatalysts prepared in Examples 1-2 and Comparative Examples 1-2. It can be seen from Figure 8 that in the N2 adsorption-desorption isotherm curve ( Figure 8 a), both BiVO4 and its Cl-doped samples show typical type-IV isotherms, indicating that they have a mesoporous structure. With the change of the Cl doping ratio, the adsorption amount of BiVO4-Cl (1:3) is significantly higher than that of other samples, indicating that its specific surface area is larger, which may help to enhance the photocatalytic activity. The pore size distribution diagram (Figure 8 b) shows that the pore sizes of all samples are mainly concentrated in the range of 5 - 15 nm, further confirming their mesoporous characteristics. Among them, BiVO4-Cl(1∶3) has a relatively large pore volume, indicating that it may have a more abundant pore structure, which is beneficial to improving the transport of reactants and the exposure of catalytic active sites. Therefore, Cl doping not only changes the specific surface area of BiVO4, but also affects its pore structure, thus possibly optimizing the photocatalytic performance.

[0064] Weigh 5 mg of the catalysts prepared in Examples 1 - 2 and Comparative Examples 1 - 2 and 2 mmol of benzylamine respectively and place them in a 50 mL quartz tube. Then add 10 mL of toluene as a solvent. Put the quartz tube containing the mixed solution into a photoreactor for dark reaction for 1 h to achieve the adsorption - desorption equilibrium between the catalyst and the reaction substrate. After 1 h, turn on the light source and continue the reaction for 6 h. After the reaction is completed, the reaction solution is centrifuged and filtered, and the supernatant is taken for the next analysis. Use a gas chromatograph to detect, and calculate the conversion rate and selectivity of each catalyst by the normalization method.

[0065] Table 1 Catalytic performance of the catalysts prepared in Examples 1 - 2 and Comparative Examples 1 - 2

[0066] Catalyst Conversion Rate (%) Selectivity (%) Comparative Example 2 <![CDATA[BiVO4]]> 35 99 Example 2 <![CDATA[BiVO4-Cl(1∶3)]]> 52 99 Example 1 <![CDATA[BiVO4-Cl(1∶1)]]> 78 99 Comparative Example 1 <![CDATA[BiVO4-Cl(3∶1)]]> 37 99

[0067] As can be seen from Table 1, for the single BiVO4 catalyst, the conversion rate of toluidine is only 35%, while the conversion rate of toluidine of the BiVO4 / BiOCl photocatalyst prepared in Example 1 of the present invention can reach 78%. It can be seen that the BiVO4 / BiOCl photocatalyst synthesized by the synthesis method provided by the present invention has a high conversion rate for toluidine.

[0068] Weigh 5 mg of the catalyst prepared in Example 1 and 10 μL of benzylamine and place them in a 50 mL quartz tube. Then add 10 mL of ethyl acetate, methanol, toluene, 1,2 - dichloroethane, carbon tetrachloride, N,N - dimethylformamide, and acetonitrile respectively as solvents. Put the quartz tube containing the mixed solution into a photoreactor for dark reaction for 1 h to achieve the adsorption - desorption equilibrium between the catalyst and the reaction substrate. After 1 h, turn on the light source and continue the reaction for 6 h. After the reaction is completed, the reaction solution is centrifuged and filtered, and the supernatant is taken for the next analysis. Detect the conversion rate and selectivity of the catalyst under different solvents, and the results are shown in Table 2.

[0069] Table 2 Catalytic performance of the catalyst prepared in Example 1 under different solvents

[0070] Serial Number Solvent Conversion Rate (%) Selectivity (%) 1 Ethyl Acetate 59 98 2 Methanol 29 98 3 Toluene 78 99 4 1,2 - Dichloroethane / / 5 Carbon Tetrachloride / / 6 N,N - Dimethylformamide 61 98 7 Acetonitrile 75 99

[0071] As can be seen from Table 2, the type of solvent also affects the conversion rate and selectivity of the catalyst. Using toluene and acetonitrile as solvents has high conversion rate and selectivity, while for 1,2-dichloroethane and carbon tetrachloride, due to their low solvent polarity, the catalytic oxidation of toluidine cannot be achieved.

[0072] 2 mmol of 2-furfurylamine, 4-methylbenzylamine, 4-methoxybenzylamine, 4-chlorobenzylamine, 3-methoxybenzylamine, 4-fluorobenzylamine, 4-(trifluoromethyl)-benzylamine, 2-methoxybenzylamine, 2-aminomethylpyridine, thiophene-2-methylamine and 5 mg of the catalyst prepared in Example 1 were respectively placed in a 50 mL quartz tube, and then 10 mL of toluene was added as a solvent. The quartz tube containing the mixed solution was placed in a photoreactor for dark reaction for 1 h to achieve the adsorption-desorption equilibrium between the catalyst and the reaction substrate. After 1 h, the light source was turned on and the reaction continued for 6 h. After the reaction was completed, the reaction solution was centrifuged and filtered, and the supernatant was taken for the next analysis to detect the conversion rate and selectivity of the catalyst prepared in Example 1 for different substrates. The results are shown in Table 3.

[0073] Table 3 Catalytic performance of the catalyst prepared in Example 1 for different substrates

[0074] Serial Number Substrate Conversion Rate (%) Selectivity (%) 1 2 - Furfurylamine 71 58 2 4 - Methylbenzylamine 100 100 3 4 - Methoxybenzylamine 77 99 4 4 - Chlorobenzylamine 86 76 5 3 - Methoxybenzylamine 64 99 6 4 - Fluorobenzylamine 100 70 7 4 - (Trifluoromethyl) - benzylamine 100 85 8 2 - Methoxybenzylamine 56 99 9 2 - (Aminomethyl)pyridine 100 100 10 Thiophene - 2 - methylamine 58 100

[0075] As can be seen from Table 3, the catalyst prepared in Example 1 of the present invention has high catalytic conversion rate and selectivity for various amine compounds, especially for 4-methylbenzylamine and 2-aminomethylpyridine, and both the catalytic conversion rate and selectivity are as high as 100%.

[0076] The above is only the preferred specific embodiment 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 those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A synthesis method of BiVO4 / BiOCl photocatalyst, characterized in that, It includes the following steps: Mix bismuth nitrate and mixed amine salts, then grind them, and then perform calcination to obtain the BiVO4 / BiOCl photocatalyst; The mixed amine salts are NH4VO3 and NH4Cl; the mass ratio of NH4VO3 to NH4Cl is 1∶(1 - 3).

2. The synthesis method of the BiVO4 / BiOCl photocatalyst according to claim 1, characterized in that, The mass ratio of bismuth nitrate to the mixed amine salts is 4∶1.

3. The synthesis method of the BiVO4 / BiOCl photocatalyst according to claim 1, characterized in that, The grinding speed is 450 r / min, the grinding time is 15 min, and the ball-to-material ratio for grinding is 4∶1.

4. The synthesis method of the BiVO4 / BiOCl photocatalyst according to claim 1, characterized in that, The calcination temperature is 500 °C, the calcination time is 6 h, and the calcination atmosphere is an air atmosphere.

5. The synthesis method of the BiVO4 / BiOCl photocatalyst according to claim 1, characterized in that, The heating mode for calcination is programmed heating.

6. The synthesis method of the BiVO4 / BiOCl photocatalyst according to claim 5, characterized in that, Specifically, the programmed heating is as follows: First, heat up to 300 °C at a heating rate of 10 °C / min, hold for 30 min, and then heat up to 500 °C at a heating rate of 2.5 °C / min and hold for 6 h.

7. The synthesis method of the BiVO4 / BiOCl photocatalyst according to claim 1, characterized in that, The mass ratio of NH4VO3 to NH4Cl is 1∶1.

8. A BiVO4 / BiOCl photocatalyst obtained by the synthesis method according to any one of claims 1 - 7.

9. Use of the BiVO4 / BiOCl photocatalyst according to claim 8 in the catalytic oxidation of amine compounds.

10. The application according to claim 9, wherein The amine compound is selected from one of benzylamine, 2-furfurylamine, 4-methylbenzylamine, 4-methoxybenzylamine, 4-chlorobenzylamine, 3-methoxybenzylamine, 4-fluorobenzylamine, 4-(trifluoromethyl)-benzylamine, 2-methoxybenzylamine, 2-aminomethylpyridine, and thiophene-2-methylamine.

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