Cerium-doped high-nuclear-number titanium-oxygen cluster compound as well as preparation method and application thereof
Through the design of cerium-doped high-nuclear-number titanium oxide clusters and the solvent-thermal synthesis method, the technical bottleneck of existing titanium oxide clusters in photocatalytic selective oxidation reactions was solved, and a catalytic effect with high selectivity and high-efficiency response was achieved. The catalyst has a stable structure after multiple cycles of use.
Patent Information
- Application Number
- CN202510800530.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-16
- Publication Date
- 2025-09-19
AI Technical Summary
Existing titanium oxide clusters have problems in photocatalytic selective oxidation reactions, such as difficult to control the band gap width resulting in insufficient visible light response, low product selectivity due to the single electronic structure of the active site, and poor reusability due to the metastable structure. The lack of precise molecular engineering strategies makes it impossible to achieve band structure optimization and directional regulation of specific reaction pathways.
A cerium-doped high-nuclear-number titanium oxide cluster was designed, and a high-nuclear-number titanium oxide cluster with anatase characteristics was prepared by regulating the variable valence state characteristics and coordination environment of trivalent cerium. The solvent thermal synthesis method was used to achieve gram-scale preparation and recycling of the catalyst.
The catalyst's oxidation selectivity for aromatic alcohols was improved, its response to visible light was enhanced, the catalytic rate was increased, and the catalyst maintained good structural stability after five cycles, with excellent selectivity and activity.
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Abstract
Description
Technical Field
[0001] The present invention relates to the fields of photocatalytic materials and fine chemical synthesis, and in particular to a cerium-doped high-nuclear-number titanium oxide cluster compound and a preparation method and application thereof. Background Art
[0002] In the fields of green chemistry and fine organic synthesis, photocatalytic selective oxidation technology has attracted considerable attention due to its ability to harness solar energy to drive molecular transformations under mild conditions. Traditional semiconductor catalysts activate oxygen molecules via photogenerated carriers to generate reactive oxygen species. However, strong oxidizing species such as hydroxyl radicals and superoxide radicals can easily lead to overoxidation of substrates, resulting in poor product selectivity and numerous side reactions. This contradiction is particularly prominent in the oxidation of complex organic compounds such as aromatic alcohols.
[0003] Titanium oxide clusters, molecular models of crystalline titanium dioxide, offer an ideal platform for studying structure-activity relationships due to their atomically precise structure. Although a variety of heterometallic-doped titanium oxide clusters have been developed, practical applications still face three technical bottlenecks: difficulty in controlling the band gap, resulting in insufficient visible light response; low product selectivity due to the monotonous electronic structure of the active site; and poor reusability due to the metastable structure. These issues stem from the lack of precise molecular engineering strategies, which prevent the simultaneous optimization of band structure and targeted regulation of specific reaction pathways.
[0004] It is particularly noteworthy that the lanthanide element cerium (Ce 3+ / Ce 4+ ) offers unique opportunities for manipulating electron transfer pathways. Its 4f-5d orbital hybridization can significantly alter the frontier molecular orbital distribution of titanyl clusters. Furthermore, the surface oxygen vacancy formation energy is lower than that of traditional metal dopants, providing a theoretical basis for constructing bifunctional catalysts with a "broad-spectrum response and selective activation." However, no titanyl cluster systems have been reported that achieve highly selective oxidation through precise control of the trivalent cerium coordination microenvironment, and even less so, synthetic methodologies for scalable preparation.
[0005] Therefore, there is an urgent need to design atomically precise cerium-doped high-nuclear-number titanium oxide clusters to achieve band gap optimization and energy transfer path design through coordination environment regulation. Summary of the Invention
[0006] In view of the above shortcomings of the prior art, the purpose of the present invention is to provide a cerium-doped high-nuclear-number titanyl cluster compound, a preparation method and an application thereof. The prepared cerium-doped high-nuclear-number titanyl cluster compound has a titanyl core that is the smallest functional fragment of anatase titanium dioxide, thereby solving the problem of ambiguous structure of traditional catalysts. Moreover, trivalent cerium doping can improve the oxidation selectivity of the high-nuclear-number titanyl cluster compound as a catalyst for aromatic alcohols. The preparation method of the present invention is a simple solvent-thermal synthesis method, which realizes the gram-scale preparation and recycling of the catalyst, effectively solving the problems existing in the prior art.
[0007] In order to achieve the above purpose or other purposes, the present invention is implemented through the following technical solutions.
[0008] A cerium-doped high-nuclear-number titanium oxide cluster compound, wherein the molecular formula of the high-nuclear-number titanium oxide cluster compound is Ti 14 Ce2(μ3-O) 18 (μ2-O)4Bz 16 (O i Pr)2DMF6·20MeCN, abbreviated as Ti 14 Ce2; where μ3-O represents a triple-bridged O atom, μ2-O represents a double-bridged O atom, Bz represents a benzoic acid ligand, and O i Pr represents an isopropyloxy ligand, DMF represents a dimethylformamide solvent molecule, and MeCN represents an acetonitrile solvent molecule.
[0009] The cerium-doped high-nuclear-number titanium oxide cluster compound of the present invention has a monoclinic crystal system, a space group of I2 / a, and a unit cell parameter a of b is c is α is 90°, β is 92.9°, γ is 90°, and the unit cell volume is
[0010] The cluster core size of the cerium-doped high-nuclear-number titanium oxide cluster compound of the present invention is 1.9-2.4 nm.
[0011] The cerium-doped high-nuclear-number titanium oxide cluster Ti of the present invention 14 Ce2(μ3-O) 18 (μ2-O)4Bz 16 (O i Pr)2DMF6·20MeCN (abbreviated as Ti 14 Ce2), Ti 12 O 22 The core is composed of two Ti6O9 units connected by four μ2-O bridges, and is surrounded by 12 Bz ligands and 2 DMF solvent molecules. Among them, the Ti6O9 unit corresponds to a structural fragment of anatase, and the two fragments are connected by the central Ti ion to form a TiO2 unit cell model.3+ With two Ti 4+ Located at the end of TiO2 core, Ce 3+ Located above the Ti4O4 rectangular structure, and connected to Ti through the bidentate Bz ligand 4+ Bridged, with another DMF molecule axially coordinated. This structure combines the characteristics of anatase with Ce 3+ Coordination regulation provides an atomic-level model for photocatalytic design.
[0012] The present invention also provides a method for preparing the cerium-doped high-nuclear-number titanium oxide cluster, comprising the following steps:
[0013] 1) adding benzoic acid and cerium chloride heptahydrate into a solvent and stirring to mix uniformly to obtain a suspension;
[0014] 2) Tetraisopropyl titanate is added to the suspension obtained in step 1), stirred evenly under sealing, and subjected to heat preservation reaction; after the reaction is completed, the target product is obtained through post-treatment.
[0015] In one example of the present invention, the molar ratio of tetraisopropyl titanate, cerium chloride heptahydrate, and benzoic acid is 3:(0.1-0.3):(9-12). Preferably, the molar ratio of tetraisopropyl titanate, cerium chloride heptahydrate, and benzoic acid is 3:0.26:12.
[0016] In one example of the present invention, the solvent is selected from one or more of ethanol, methanol, isopropanol, tetrahydrofuran, acetonitrile, and dimethylformamide. Preferably, the solvent is selected from a mixed solvent of acetonitrile and dimethylformamide, and the volume ratio of acetonitrile to dimethylformamide is 1:1. The mixed solvent of acetonitrile and dimethylformamide can have both polarity and coordination ability, promote the hydrolysis of tetraisopropyl titanate and the coordination of benzoic acid ligands, and avoid Ce 3+ Hydrolysis generates Ce(OH)3 precipitate.
[0017] In one example of the present invention, the reaction temperature in step 2) is 95°C to 105°C. Too high a reaction temperature will cause the ligand to decompose; too low a reaction temperature will result in incomplete reaction. In one example of the present invention, the reaction time in step 2) is 7 days to 14 days.
[0018] In one embodiment of the present invention, post-treatment includes but is not limited to washing and vacuum drying. Preferably, acetonitrile is used for washing, and the vacuum drying temperature is 20 to 60° C. and the drying time is 2 to 24 hours.
[0019] The present invention also provides the use of the cerium-doped high-nuclear-number titanium oxide cluster compound in a photocatalytic selective oxidation reaction.
[0020] A method for preparing aldehydes from aromatic alcohols by utilizing a photocatalytic selective oxidation reaction, wherein a cerium-doped high-nuclear-number titanium oxide cluster is used as a catalyst, and the aromatic alcohol is selected from one or more of benzyl alcohol, p-methoxybenzyl alcohol, p-methylbenzyl alcohol, p-bromobenzyl alcohol, p-chlorobenzyl alcohol, and p-fluorobenzyl alcohol.
[0021] Furthermore, the method comprises the following steps: dissolving a mixture of a high-nuclear-number titanium oxide cluster compound doped with cerium catalyst and an aromatic alcohol in toluene, adding a co-catalyst, and reacting under an oxygen atmosphere under light, obtaining an aldehyde compound after the reaction is completed, and centrifuging the catalyst TiO2 to obtain the aldehyde compound. 14 Ce2, the catalyst Ti 14 Ce2 was washed with toluene and dried for recycling.
[0022] In one example of the present invention, the molar ratio of the cerium-doped high-nuclear-number titanium oxide cluster, the aromatic alcohol, and the co-catalyst is (0.005-0.006):(0.1-0.5):13.
[0023] In one embodiment of the present invention, the co-catalyst is selected from triethylamine.
[0024] In one example of the present invention, the O2 pressure is 1 atm, and the amount of toluene used ensures that the concentration of the aromatic alcohol is 0.1 to 0.5 mmol / mL.
[0025] In one embodiment of the present invention, when λ≥400nm and light intensity is 134mW / cm 2 The illumination reaction is carried out under visible light, the illumination reaction time is 30h~35h, and the illumination temperature is 23℃~27℃.
[0026] The present invention provides a cerium-doped high-nuclear-number titanium oxide cluster and its preparation method. The high-nuclear-number titanium oxide cluster is obtained by a solvothermal synthesis method, where the reaction raw materials are mixed and then heated in a solvent for reaction. The preparation method is simple, and the raw materials are readily available, making it easy to industrialize. The reaction process does not require a template or surfactant, resulting in low raw material costs, simple post-processing, and minimal pollution, thus meeting environmental protection requirements.
[0027] The cerium-doped high-nuclear-number titanium oxide cluster prepared by the preparation method of the present invention has high selectivity due to Ce doping, and improves the oxidation selectivity of aromatic alcohols (selectivity greater than 99%), especially the oxidation selectivity of p-methoxybenzyl alcohol greater than 99%, without the generation of benzoic acid, which is significantly improved compared with the prior art (the selectivity of TiO2 P25 in the prior art is only 44%). Moreover, after Ce doping, the high-nuclear-number titanium oxide cluster has a high efficiency response to visible light. At λ>400nm, the high-nuclear-number titanium oxide cluster Ti of the present invention has a high selectivity response to visible light. 14The catalytic rate of Ce2 (TOF = 1.8h-1) is higher than that of Ti8; and it has excellent stability. It is used in the catalytic oxidation reaction of aromatic alcohols. After five recycling cycles, Ti 14 The conversion rate of Ce2 dropped from 100% to 91%, but XRD and IR showed that the crystal structure had no obvious change, which was better than that of similar catalysts. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 The cerium-doped high-nuclear-number titanium oxide cluster Ti prepared in Example 1 14 Crystal photo of Ce2 (the crystal photo was taken under a microscope, and the size is marked in the photo).
[0029] Figure 2 The cerium-doped high-nuclear-number titanium oxide cluster Ti prepared in Example 1 14 The crystal structure of a single crystal of Ce2 (hydrogen is ignored for clarity).
[0030] Figure 3 The cerium-doped high-nuclear-number titanium oxide cluster Ti prepared in Example 1 14 Powder X-ray diffraction pattern of Ce2.
[0031] Figure 4 The cerium-doped high-nuclear-number titanium oxide cluster Ti prepared in Example 1 14 UV-vis DRS spectrum of Ce2.
[0032] Figure 5 The cerium-doped high-nuclear-number titanium oxide cluster Ti prepared in Example 1 14 Conversion and selectivity of Ce2-catalyzed oxidation of p-methoxybenzyl alcohol at different times.
[0033] Figure 6 The cerium-doped high-nuclear-number titanium oxide cluster Ti prepared in Example 1 14 When Ce2 catalyzed the oxidation reaction of p-methoxybenzyl alcohol, the conversion rates were compared after five repeated experiments.
[0034] Figure 7a The cerium-doped high-nuclear-number titanium oxide cluster Ti prepared in Example 1 14 Ce2, Ti catalyst after participating in 5 photocatalytic selective oxidation reactions 14 Comparison of infrared spectra of Ce2.
[0035] Figure 7b The cerium-doped high-nuclear-number titanium oxide cluster Ti prepared in Example 1 14 Ce2, Ti, a catalyst that has participated in five photocatalytic selective oxidation reactions 14 Comparison of XRD spectra of Ce2. DETAILED DESCRIPTION
[0036] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following examples and the features in the examples can be combined with each other unless they conflict. It should also be understood that the terms used in the examples of the present invention are for the purpose of describing specific embodiments, not for the purpose of limiting the scope of protection of the present invention. The test methods for which specific conditions are not specified in the following examples are generally carried out under conventional conditions or under the conditions recommended by the manufacturers.
[0037] It should be noted that the terms such as "upper", "lower", "left", "right", "middle" and "one" cited in this specification are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of the present invention without substantially changing the technical content.
[0038] The technical scheme of the present invention is described in detail below through several specific examples and comparative examples. Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by conventional methods in the art. Unless otherwise specified, the detection methods used in the examples of the present invention are conventional detection methods in the industry.
[0039] Example 1
[0040] Ce-doped high-nuclear-number titanium oxide clusters Ti 14 The preparation method of Ce2 is as follows:
[0041] Benzoic acid (1.46 g, 12 mmol) and CeCl3·7H2O (0.10 g, 0.26 mmol) were added to a 20 mL cillin bottle, and 4 mL of acetonitrile-DMF (v:v=1:1) was added. Tetraisopropyl titanate (0.92 mL, 3 mmol) was added under stirring. After stirring for 1 h, the vial was sealed and heated in an oven at 100°C for 2 weeks. After the reaction was completed, it was filtered, washed with acetonitrile, and dried in vacuo at 60°C for 2 h to obtain red block crystals with a yield of 20.7%.
[0042] The obtained red block crystals were photographed under a microscope, and the obtained photos were as follows Figure 1 As shown, it can be seen that the obtained crystals are blocky red silk crystals with a cluster core size of 1.9 to 2.4 nm.
[0043] Take the red block crystal for X-ray single crystal diffraction test, the structure is as follows Figure 2 As shown, the obtained product is determined to be the cerium-doped high-nuclear-number titanium oxide cluster Ti of the present invention. 14 Ce2, as can be seen from the figure, Ti 14 Ce2 clusters with Ti 12 O 22 The core is composed of two Ti6O9 units connected by four μ2-O bridges, and is surrounded by 12 Bz ligands and 2 DMF solvent molecules. Among them, the Ti6O9 unit corresponds to a structural fragment of anatase, and the two fragments are connected by the central Ti ion to form a TiO2 unit cell model. 3+ With two Ti 4+ Located at the end of TiO2 core, Ce 3+ Located above the Ti4O4 rectangular structure, and connected to Ti through the bidentate Bz ligand 4+ Bridged, with another DMF molecule coordinated axially.
[0044] After fully grinding the red block crystals, X-ray powder diffraction test was performed, such as Figure 3 As shown in the figure, it can be seen that the Ti prepared in the embodiment of the present invention 14 The XRD pattern of Ce2 is highly consistent with the simulated spectrum in terms of the main diffraction peak positions in the range of 2θ=10°~50°, indicating that the target cluster structure was successfully obtained.
[0045] Take the dried red block crystals and spectrally pure barium sulfate at a ratio of 1:50 to 1:200, grind and mix, and fill the sample cell with the powder. After preheating the UV-Vis spectrophotometer, set the wavelength to 200 to 400 nm, calibrate with pure barium sulfate as a reference, scan the sample absorbance, and analyze the characteristic peaks after subtracting the background. The results are as follows Figure 4 As shown in the figure, it can be seen that Ti 14 The absorption band edge of the Ce2 cluster reaches 680nm, indicating that the cluster can efficiently respond to visible light. Ce doping effectively broadens the light response range, enabling it to exhibit excellent capture capabilities in the ultraviolet-visible region.
[0046] Example 2
[0047] The difference between this embodiment and embodiment 1 is that the molar ratio of tetraisopropyl titanate, cerium chloride heptahydrate, and benzoic acid is 3:0.3:10, the solvent is acetonitrile, the reaction temperature is 105°C, the reaction time is 10 days, the vacuum drying temperature is 20°C, and the drying time is 24 hours.
[0048] Example 3
[0049] The difference between this embodiment and embodiment 1 is that the molar ratio of tetraisopropyl titanate, cerium chloride heptahydrate, and benzoic acid is 3:0.1:9, the solvent is dimethylformamide, the reaction temperature is 95°C, the reaction time is 14 days, the vacuum drying temperature is 40°C, and the drying time is 10 hours.
[0050] Example 4
[0051] The difference between this embodiment and embodiment 1 is that the molar ratio of tetraisopropyl titanate, cerium chloride heptahydrate, and benzoic acid is 3:0.2:11, the solvent is isopropanol, the reaction temperature is 100°C, the reaction time is 7 days, the vacuum drying temperature is 30°C, and the drying time is 15 hours.
[0052] Application Example 1
[0053] Take 20 mg (5.3 μmol) of Ce-doped high-nuclear-number titanium oxide cluster Ti prepared in Example 1 14 Ce2, 38uL (0.3mmol) of p-methoxybenzyl alcohol, 3mL of toluene, 5uL of triethylamine and 0.1g of biphenyl (as internal standard) were added to the reaction vessel, stirred evenly, sealed, and filled with oxygen for 10 minutes. A balloon was tied to ensure sufficient oxygen and to prevent substrate loss. The reaction system was irradiated from the side by a 300W xenon lamp (λ>400nm), and the reaction system was placed in a well-ventilated photoreaction chamber water bath to maintain a constant temperature. At reaction times of 0h, 10h, 20h, and 30h, the reaction system was taken for gas chromatography quantitative analysis to analyze the benzyl alcohol substrate and the benzaldehyde product. Figure 5 As shown in the figure, it can be seen that Ti 14 Ce2 almost completely converted the p-methoxy group within 30 hours, with p-anisaldehyde being the sole product. The TOF was approximately 1.8 per mole of catalyst per hour. Once the reaction was complete, no benzoic acid was produced even after extended reaction time, demonstrating the mild oxidizing power and excellent selectivity of this photocatalytic system.
[0054] After the reaction, the catalyst Ti was separated by centrifugation. 14 Ce2, the catalyst Ti 14 Ce2 was washed with toluene and dried. 14 Ce2 is put into the above-mentioned photocatalytic selective oxidation reaction again, and the catalyst Ti is recovered after the reaction is completed. 14 Ce2, and so on, the catalyst Ti 14 Ce2 was put into the above photocatalytic selective oxidation reaction and repeated 5 times; the conversion rate of each time was as follows Figure 6 As shown in the figure, it can be seen that the catalyst Ti 14The conversion rate of Ce2 was 100% when it was first put into the photocatalytic selective oxidation reaction, and it could still reach 91% after five cycles.
[0055] The catalyst Ti that participated in five photocatalytic selective oxidation reactions 14 Ce2 was recovered and subjected to infrared spectrum and XRD detection. The results were as follows: Figure 7a ), 7b), it can be seen from the figure that the XRD peak position of the catalyst after 5 times of photocatalytic selective oxidation reaction is consistent with that of the catalyst before participating in the reaction ( Figure 7a 、 7b ), it can be seen that the cerium-doped high-nuclear-number titanium oxide cluster Ti of the embodiment of the present invention 14 Ce2 has excellent stability, and its crystal structure does not change significantly even after five photocatalytic selective oxidation reactions.
[0056] Application Example 2
[0057] The difference between this embodiment and Application Example 1 is that:
[0058] The aromatic alcohol is p-methylbenzyl alcohol, the molar ratio of the cerium-doped high-nuclear-number titanium oxide cluster, the aromatic alcohol, and the co-catalyst is 0.006:0.1:13, the amount of toluene used ensures that the concentration of p-methylbenzyl alcohol is 0.1 mmol / mL, and other conditions remain unchanged.
[0059] Application Example 3
[0060] The difference between this embodiment and Application Example 1 is that:
[0061] The aromatic alcohol is benzyl alcohol, the molar ratio of the cerium-doped high-nuclear-number titanium oxide cluster, the aromatic alcohol, and the co-catalyst is 0.005:0.3:13, the amount of toluene is such that the concentration of the benzyl alcohol is 0.3 mmol / mL, and other conditions remain unchanged.
[0062] Application Example 4
[0063] The difference between this embodiment and Application Example 1 is that:
[0064] The aromatic alcohol is p-bromobenzyl alcohol, the molar ratio of the cerium-doped high-nuclear-number titanium oxide cluster, the aromatic alcohol, and the co-catalyst is 0.005:0.5:13, the amount of toluene used ensures that the concentration of p-bromobenzyl alcohol is 0.5 mmol / mL, and other conditions remain unchanged.
[0065] Application Example 5
[0066] The difference between this embodiment and Application Example 1 is that:
[0067] The aromatic alcohol is p-chlorobenzyl alcohol, the molar ratio of the cerium-doped high-nuclear-number titanium oxide cluster, the aromatic alcohol, and the co-catalyst is 0.006:0.5:13, the amount of toluene used ensures that the concentration of p-chlorobenzyl alcohol is 0.1 mmol / mL, and other conditions remain unchanged.
[0068] Application Example 6
[0069] The difference between this embodiment and Application Example 1 is that:
[0070] The aromatic alcohol is p-fluorobenzyl alcohol, the molar ratio of the cerium-doped high-nuclear-number titanium oxide cluster, the aromatic alcohol, and the co-catalyst is 0.005:0.5:13, the amount of toluene used ensures that the concentration of p-fluorobenzyl alcohol is 0.1 mmol / mL, and other conditions remain unchanged.
[0071] The conversion rates and selectivities in Application Examples 2 to 6 are compared, as shown in Table 1. It can be seen from the table that the cerium-doped high-nuclear-number titanium oxide cluster Ti prepared in Example 1 of the present invention has a high conversion rate and selectivity. 14 The selectivity of Ce2-catalyzed oxidation of benzyl alcohol, p-methylbenzyl alcohol, p-bromobenzyl alcohol, p-chlorobenzyl alcohol, and p-fluorobenzyl alcohol is greater than 99%.
[0072] Table 1 Cerium-doped high-nuclear-number titanium oxide clusters Ti 14 Selectivity of Ce2-catalyzed oxidation of p-benzyl alcohol, p-methylbenzyl alcohol, p-bromobenzyl alcohol, p-chlorobenzyl alcohol, and p-fluorobenzyl alcohol
[0073]
[0074] Comparative Example 1
[0075] Ti8 catalytic performance, the steps are as follows:
[0076] Same application example, catalyst replaced with Ti8O8Bz 16 (20 mg, 5.3 μmol); 30 h conversion rate 24%, selectivity 90%, by-product benzoic acid accounted for 10%, proving that the undoped cluster compound lacks Ce 3+ The selectivity of aromatic alcohol oxidation is poor.
[0077] Comparative Example 2
[0078] TiO2 P25 comparison, the steps are as follows:
[0079] In the same application example, the catalyst was replaced by TiO2 P25 (20 mg); the conversion rate was nearly 100% in 30 h, but the selectivity was only 44%, with benzoic acid as the main product (56%), proving that the undoped cluster compound lacked Ce. 3+ The selectivity of aromatic alcohol oxidation is poor.
[0080] From the above, it can be seen that the cerium-doped high-nuclear-number titanium oxide cluster Ti prepared by the present invention 14 Ce2 has a high oxidation selectivity for aromatic alcohols, with a selectivity greater than 99%, and a high catalytic rate and good stability. After five recycling cycles, its structure has not changed significantly and it still has a high selectivity.
[0081] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.
Claims
1. A cerium-doped high-nuclear-number titanium oxide cluster, characterized in that: The molecular formula of the high-nuclear-number titanium oxide cluster is Ti 14 Ce2(μ3-O) 18 (μ2-O)4Bz 16 (O i Pr)2DMF6·20MeCN, abbreviated as Ti 14 Ce2; Among them, μ3-O represents a triple-bridged O atom, μ2-O represents a double-bridged O atom, Bz represents a benzoic acid ligand, and O i Pr represents an isopropyloxy ligand, DMF represents a dimethylformamide solvent molecule, and MeCN represents an acetonitrile solvent molecule.
2. The cerium-doped high-nuclear-number titanium oxide cluster according to claim 1, wherein: The high-nuclear-number titanium oxide cluster crystalline material has a monoclinic crystal system, a space group of I2 / a, and a unit cell parameter a. b is c is α is 90°, β is 92.9°, γ is 90°, and the unit cell volume is 3. A method for preparing the cerium-doped high-nuclear-number titanium oxide cluster compound according to claim 1 or 2, characterized in that: The following steps are involved: 1) adding benzoic acid and cerium chloride heptahydrate into a solvent and stirring to mix uniformly to obtain a suspension; 2) Tetraisopropyl titanate is added to the suspension obtained in step 1), and the mixture is stirred evenly under sealing and heat preservation for reaction. After the reaction is completed, the target product is obtained through post-treatment.
4. The method according to claim 3, wherein: Include one or more of the following technical features: The molar ratio of tetraisopropyl titanate, cerium chloride heptahydrate, and benzoic acid is 3:(0.1-0.3):(9-12); The solvent is selected from one or more of ethanol, methanol, isopropanol, tetrahydrofuran, acetonitrile, and dimethylformamide; In step 2), the reaction temperature is 95° C. to 105° C., and the reaction time is 7 d to 14 d.
5. The method according to claim 4, wherein: The solvent is a mixed solvent of acetonitrile and dimethylformamide, and the volume ratio of acetonitrile to dimethylformamide is 1:
1.
6. Use of the cerium-doped high-nuclear-number titanium oxide cluster compound according to claim 1 or 2, or the cerium-doped high-nuclear-number titanium oxide cluster compound prepared by the method according to any one of claims 3 to 5 in a photocatalytic selective oxidation reaction.
7. A method for preparing aldehydes from aromatic alcohols using a photocatalytic selective oxidation reaction, characterized in that: The cerium-doped high-nuclear-number titanium oxide cluster compound according to claim 1 or 2, or the cerium-doped high-nuclear-number titanium oxide cluster compound prepared by the method according to any one of claims 3 to 5 is used as a catalyst, and the aromatic alcohol is selected from one or more of benzyl alcohol, p-methoxybenzyl alcohol, p-methylbenzyl alcohol, p-bromobenzyl alcohol, p-chlorobenzyl alcohol, and p-fluorobenzyl alcohol.
8. The method according to claim 7, wherein: The method comprises the following steps: dissolving a mixture of a high-nuclear-number titanium oxide cluster compound doped with cerium catalyst and an aromatic alcohol in toluene, adding a co-catalyst, and performing light-induced reaction under an oxygen atmosphere. After the reaction is completed, an aldehyde compound is obtained, and the catalyst Ti is centrifuged to separate the catalyst TiO2. 14 Ce2, the catalyst Ti 14 Ce2 was washed with toluene and dried for recycling.
9. The method according to claim 8, wherein: The molar ratio of the cerium-doped high-nuclear-number titanium oxide cluster compound, aromatic alcohol and co-catalyst is (0.005-0.006): (0.1-0.5):13; the co-catalyst is selected from triethylamine.
10. The method according to claim 8, wherein: At λ≥400nm and light intensity 134mW / cm 2 The illumination reaction is carried out under visible light, the illumination reaction time is 30h~35h, and the illumination temperature is 23℃~27℃.