Zirconium-based organic layer photocatalyst post-modified by heterogeneous metal Fe as well as preparation method and application of zirconium-based organic layer photocatalyst post-modified by heterogeneous metal Fe
By introducing Fe3+ onto a zirconium-based organic layer, a Fe single-atom catalyst was constructed, which solved the problem of limited adsorption area of the active catalytic center in photocatalysts, achieving a highly efficient toluene oxidation reaction and improving the activity and selectivity of the catalyst.
Patent Information
- Application Number
- CN202511044215.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-28
- Publication Date
- 2025-11-07
AI Technical Summary
Existing photocatalysts suffer from limited adsorption area of catalytic active sites during hydrocarbon oxidation, resulting in low substrate conversion and poor selectivity. This is especially true under high temperature, high pressure, and strong oxidant conditions, which generate unwanted byproducts and cause slow kinetics in water oxidation.
A zirconium-based organic layer photocatalyst modified with heterometallic Fe was developed. By introducing Fe3+ onto the Zr-O cluster, a Fe single-atom catalyst was constructed. The coordination and combination of Fe3+ with the Zr-O cluster generated Fe/Zr-MOL, which improved the photoresponse and the adsorption and activation of water molecules, thereby activating the CH bond.
The photocatalytic oxidation of toluene and its derivatives was achieved at ambient temperature with a toluene conversion rate of 96% and a benzoic acid selectivity of 100%, demonstrating excellent catalytic activity and recyclability.
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Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of photocatalytic material preparation, and particularly relates to a zirconium-based organic layer photocatalyst after modified by a heterometal Fe as well as a preparation method and application thereof. BACKGROUND
[0002] The selective oxidation of hydrocarbons can produce high-value-added chemicals such as alcohols, aldehydes, ketones and epoxides, and is an indispensable process in current catalysis and chemical production. Although it has been developed for decades, the thermal catalytic C(sp 3 )-H bond activation reaction still requires high temperature, high pressure and strong oxidant, thereby resulting in considerable energy consumption and related environmental impact. In addition, the harsh reaction conditions lead to excessive oxidation of the substrate to generate unwanted byproducts. The traditional method is to limit the substrate conversion rate to achieve high selectivity to the intermediate product, which undoubtedly increases the cost of the required separation steps. Therefore, the selective photocatalytic oxidation of hydrocarbons using oxygen has been identified as a highly preferred chemical process. In recent years, researchers have reported various effective photocatalysts, especially oxide semiconductors with a wide band gap (including TiO2, Bi2WO6, BiOBr), and the activity of these catalysts has been further enhanced by face regulation, surface defect engineering and composite material design. However, we have noticed that for such photocatalysts (which generate C-H bond activation by photo-generated holes, the limited contact area and adsorption center will seriously affect the catalytic performance. By utilizing active radicals (such as hydroxyl radicals and Noxyl radicals) to activate C-H bonds, the problem of photocatalysts lacking active center adsorption of hydrocarbons can be solved. Hydroxyl radicals are an important active species in photocatalysis, which can be easily formed by water oxidation (H2O*+h + →·OH*+H + ) and dispersed in the solution to react with substrate molecules. Therefore, the use of hydroxyl radicals can bypass the limitation caused by the limited contact area, providing a more universal and effective way for photocatalytic activation of saturated C-H bonds. However, due to the slow kinetics of the water oxidation process, only long-lived holes can initiate the reaction, and most photo-generated electrons and holes are recombined. Therefore, the development of a catalyst for efficient photocatalytic oxidation of toluene is the core. SUMMARY
[0003] In order to solve the problems existing in the prior art, the purpose of the present application is to provide a zirconium-based organic layer photocatalyst after modified by a heterometal Fe as well as a preparation method and application thereof, which takes a metal organic layer (Zr-MOL) as a carrier, introduces a heterometal Fe 3+The Fe single atom catalyst with a clear coordination microenvironment is constructed, has good light response, and the Fe nuclear number improves the adsorption and activation of water molecules, thereby realizing the oxidation of toluene and obviously improving the activity of the photocatalytic toluene oxidation.
[0004] In order to achieve the above technical purpose, the present application adopts the following technical scheme:
[0005] A zirconium-based organic layer photocatalyst with heterogeneous metal Fe post-modification, taking a zirconium-based organic layer Zr-MOL as a carrier, and introducing a heterogeneous metal Fe on a Zr-O cluster 3+ The loading amount of the Fe 3+ is 3.6-4wt%, and the atomic ratio of Zr and Fe is 6:2.3-2.7.
[0006] The present application also provides a preparation method of the above-mentioned zirconium-based organic layer photocatalyst with heterogeneous metal Fe post-modification, first assembling a Zr-MOL layer structure through a solvothermal method, then introducing Fe 3+ by using the Zr-MOL as a carrier through an impregnation method, and obtaining Fe / Zr-MOL after solid-liquid separation, washing and drying.
[0007] As a preferred, the specific process of the solvothermal method is that: first, dissolve a zirconium-based precursor in DMF and acetic acid, mix thoroughly, and then react at 70-100 DEG C for 1-3h; then add 2,4,6-tris (4-carboxyl phenyl)-1,3,5-triazine, continue to react at 110-130 DEG C for 1-3h.
[0008] As a preferred, the volume ratio of DMF and acetic acid is 3:2.
[0009] As a preferred, the specific process of the impregnation method is that: first, add Zr-MOL to an acetonitrile solution of FeCl3·6H2O, ultrasonic dispersion, and then stir and react at 70-90 DEG C for 12-20h.
[0010] The present application also provides an application of the above-mentioned zirconium-based organic layer photocatalyst with heterogeneous metal Fe post-modification, which is used for the oxidation reaction of toluene and its derivatives.
[0011] In the present application, Fe 3+ ions are introduced to coordinate and combine with Zr-oxygen cluster to generate Fe-doped Zr-MOL (denoted as Fe / Zr-MOL). Fe 3+ is introduced to induce the MCCT process in MOL, that is, Fe 3+charge transfer to the Zr-oxo cluster, which leads to the extension of visible light response. The unique transformation of MCCT enables Fe / Zr-MOL to catalyze the oxidation of H2O to hydroxyl radical (·OH), which has sufficient oxidation ability to activate C-H bond. Therefore, in sharp contrast to Zr-MOL, which is completely inert, Fe / Zr-MOL with strong oxidation ability exhibits excellent activity and recyclability for the photocatalytic oxidation of toluene and its derivatives with water under ambient temperature 1 bar O2.
[0012] Compared with the prior art, the present application has the following advantages:
[0013] The present application introduces a hetero-metal Fe on the Zr-O cluster with a metal-organic layer (Zr-MOL) as a carrier 3+ , constructs a Fe single-atom catalyst with a clear coordination microenvironment, has good light response, and the number of Fe cores improves the adsorption and activation of water molecules to realize the oxidation of toluene, thereby significantly improving the activity of photocatalytic toluene oxidation. For example, under full-spectrum light irradiation, without adding any sacrificial agent, the conversion of toluene reached 96% and the selectivity of benzoic acid was 100% in the toluene oxidation reaction catalyzed by Fe / Zr-MOL for 2 h. BRIEF DESCRIPTION OF DRAWINGS
[0014] Figure 1 TEM spectra of Fe-MOL-200-16 prepared in Example 1 and MOL prepared in Comparative Example 6.
[0015] Figure 2 XPS chart of Fe-MOL-200-16 prepared in Example 1.
[0016] Figure 3 In-situ infrared chart of Fe-MOL-200-16 prepared in Example 1 and MOL prepared in Comparative Example 6.
[0017] Figure 4 Steady-state fluorescence chart of Fe-MOL-200-16 prepared in Example 1 and MOL prepared in Comparative Example 6. DETAILED DESCRIPTION
[0018] The present application will be further described in detail below in conjunction with examples, but the scope of protection of the present application is not limited to these examples.
[0019] The experimental methods used in the following examples are as follows unless otherwise specified. They are all conventional methods; the reagents, materials, etc. used in the following examples can be obtained from commercial channels unless otherwise specified.
[0020] Photocatalytic toluene oxidation:
[0021] 5 mg of catalyst powder was weighed into 2 mL of acetonitrile, dispersed for 5 min under ultrasonic and then transferred to a reaction tube, frozen with liquid nitrogen, vacuumed, backfilled with ultra-pure nitrogen, and repeated three times. The xenon lamp light source was turned on under stirring, and the full-spectrum light irradiation was continued for 2 h. After the reaction was completed, the mixture was centrifuged to take the supernatant, and filtered with a 0.22 μm oil system filter head. The final clear liquid was used for quantitative analysis by gas chromatograph by internal standard method.
[0022] Example 1
[0023] Preparation of Fe-MOL-200-16 nanosheets:
[0024] In a 20 mL glass bottle with a cap, 190 mg of ZrOCl2·8H2O, 6 mL of DMF, and 4 mL of glacial acetic acid were sequentially added, mixed well, and then reacted in an 85°C oven for 2 h. Then 44 mg of H3TATB was added, and the temperature was raised to 120°C for continuous reaction for 12 h. The solid was collected by centrifugation and washed with DMF, acetone three times in turn. The solid material was dried in a 60°C vacuum oven for 12 h to obtain white powder MOL. In a 4 mL acetonitrile solution containing 200 mg of FeCl3·6H2O, 40 mg of MOL was added and ultrasonically dispersed for 5 min. Stirring was carried out in an 85°C oil bath for 16 h. After cooling to room temperature, the solid was collected by centrifugation, washed with deionized water and anhydrous methanol, and dried in a 60°C vacuum oven for 12 h to obtain light brick red nanosheets Fe-MOL-200-16.
[0025] As shown in Table 1, Fe-MOL-200-16 was further confirmed by ICP-AES that the Fe loading was about 3.81wt%, and the atomic ratio of Zr and Fe was 6:2.5, respectively. The results of photocatalytic toluene oxidation reaction are shown in Table 2.
[0026] Comparative Example 1
[0027] Preparation of Fe-MOL-200-8 nanosheets:
[0028] Into a 20 mL capped glass bottle, 190 mg of ZrOCl2*8H2O, 6 mL of DMF, 4 mL of glacial acetic acid were added in sequence, mixed well and then reacted in an 85 °C oven for 2 h. 44 mg of H3TATB was added and the temperature was raised to 120 °C for further reaction for 12 h. The solid was collected by centrifugation and washed with DMF, acetone for three times in sequence. The solid material was dried in a vacuum oven at 60 °C for 12 h to obtain white powder MOL. Into a solution containing 200 mg of FeCl3*6H2O in 4 mL of acetonitrile, 40 mg of MOL was added and ultrasonically dispersed for 5 min. The mixture was stirred in an 85 °C oil bath for 8 h. After cooling to room temperature, the solid was collected by centrifugation and washed with deionized water and anhydrous methanol, respectively, and dried in a vacuum oven at 60 °C for 12 h to obtain light brick red nanosheets Fe-MOL-200-8.
[0029] As shown in Table 1, Fe-MOL-200-8 was further confirmed by ICP-AES that the Fe loading was about 2.02 wt%, the atomic ratio of Zr and Fe was 6:1.3, respectively, and the results of photocatalytic toluene oxidation reaction were shown in Table 2.
[0030] Comparative Example 2
[0031] Preparation of Fe-MOL-200-12 nanosheets:
[0032] Into a 20 mL capped glass bottle, 190 mg of ZrOCl2*8H2O, 6 mL of DMF, 4 mL of glacial acetic acid were added in sequence, mixed well and then reacted in an 85 °C oven for 2 h. 44 mg of H3TATB was added and the temperature was raised to 120 °C for further reaction for 12 h. The solid was collected by centrifugation and washed with DMF, acetone for three times in sequence. The solid material was dried in a vacuum oven at 60 °C for 12 h to obtain white powder MOL. Into a solution containing 200 mg of FeCl3*6H2O in 4 mL of acetonitrile, 40 mg of MOL was added and ultrasonically dispersed for 5 min. The mixture was stirred in an 85 °C oil bath for 8 h. After cooling to room temperature, the solid was collected by centrifugation and washed with deionized water and anhydrous methanol, respectively, and dried in a vacuum oven at 60 °C for 12 h to obtain light brick red nanosheets Fe-MOL-200-8.
[0033] As shown in Table 1, Fe-MOL-200-12 was further confirmed by ICP-AES that the Fe loading was about 3.55 wt%, the atomic ratio of Zr and Fe was 6:1.1, respectively, and the results of photocatalytic toluene oxidation reaction were shown in Table 2.
[0034] Comparative Example 3
[0035] Preparation of Fe-MOL-200-20 nanosheets:
[0036] Into a 20 mL capped glass bottle, 190 mg of ZrOCl2*8H2O, 6 mL of DMF, 4 mL of glacial acetic acid were added in sequence, mixed well and then reacted in an 85 °C oven for 2 h. 44 mg of H3TATB was added and the temperature was raised to 120 °C for further reaction for 12 h. The solid was collected by centrifugation and washed with DMF, acetone for three times in sequence. The solid material was dried in a vacuum oven at 60 °C for 12 h to obtain white powder MOL. Into a solution containing 200 mg of FeCl3*6H2O in 4 mL of acetonitrile, 40 mg of MOL was added and ultrasonically dispersed for 5 min. The mixture was stirred in an 85 °C oil bath for 20 h. After cooling to room temperature, the solid was collected by centrifugation and washed with deionized water and anhydrous methanol, respectively, and dried in a vacuum oven at 60 °C for 12 h to obtain light brick red nanosheets Fe-MOL-200-20.
[0037] As shown in Table 1, Fe-MOL-200-20 was further confirmed by ICP-AES that the Fe loading was about 4.25 wt%, the atomic ratio of Zr and Fe was 6:2.8, respectively, and the results of photocatalytic toluene oxidation reaction were shown in Table 2.
[0038] Comparative Example 4
[0039] Preparation of Fe-MOL-200-24 nanosheets:
[0040] Into a 20 mL capped glass bottle, 190 mg of ZrOCl2*8H2O, 6 mL of DMF, 4 mL of glacial acetic acid were added in sequence, mixed well and then reacted in an 85 °C oven for 2 h. 44 mg of H3TATB was added and the temperature was raised to 120 °C for further reaction for 12 h. The solid was collected by centrifugation and washed with DMF, acetone for three times in sequence. The solid material was dried in a vacuum oven at 60 °C for 12 h to obtain white powder MOL. Into a solution containing 200 mg of FeCl3*6H2O in 4 mL of acetonitrile, 40 mg of MOL was added and ultrasonically dispersed for 5 min. The mixture was stirred in an 85 °C oil bath for 20 h. After cooling to room temperature, the solid was collected by centrifugation and washed with deionized water and anhydrous methanol, respectively, and dried in a vacuum oven at 60 °C for 12 h to obtain light brick red nanosheets Fe-MOL-200-20.
[0041] As shown in Table 1, Fe-MOL-200-24 was further confirmed by ICP-AES that the Fe loading was about 4.68 wt%, the atomic ratio of Zr and Fe was 6:3.1, respectively, and the results of photocatalytic toluene oxidation reaction were shown in Table 2.
[0042] Comparative Example 5
[0043] Preparation of Fe-MOL-250-6 nanosheets:
[0044] In a 20 mL glass bottle with a cap, 190 mg of ZrOCl2·8H2O, 6 mL of DMF, 4 mL of glacial acetic acid were added in turn, mixed uniformly, and then reacted in an 85°C oven for 2 h. Then 44 mg of H3TATB was added, and the temperature was raised to 120°C for 12 h of continuous reaction. The solid was collected by centrifugation and washed with DMF, acetone three times in turn. The solid material was dried in a 60°C vacuum oven for 12 h to obtain white powder MOL. In a solution containing 250 mg of FeCl3·6H2O in 4 mL of acetonitrile, 40 mg of MOL was added and ultrasonically dispersed for 5 min. Stirring was carried out in an 85°C oil bath for 6 h. After cooling to room temperature, the solid was collected by centrifugation and washed with deionized water and anhydrous methanol, respectively, and dried in a 60°C vacuum oven for 12 h to obtain light brick red nanosheets Fe-MOL-250-6.
[0045] As shown in Table 1, Fe-MOL-250-6 was further confirmed by ICP-AES that the Fe loading was about 1.87wt%, respectively, and the atomic ratio of Zr, Fe was 6:1.2, respectively. The results of the photocatalytic toluene oxidation reaction are shown in Table 2.
[0046] Table 1 ICP-AES content of each metal element of the samples prepared in Example 1 and Comparative Examples 1-5
[0047]
[0048] Table 2 Photocatalytic toluene oxidation reaction results of the samples prepared in Example 1 and Comparative Examples 1-5
[0049]
[0050] Comparative Example 6
[0051] In a 20 mL glass bottle with a cap, 190 mg of ZrOCl2·8H2O, 6 mL of DMF, 4 mL of glacial acetic acid were added in turn, mixed uniformly, and then reacted in an 85°C oven for 2 h. Then 44 mg of H3TATB was added, and the temperature was raised to 120°C for 12 h of continuous reaction. The solid was collected by centrifugation and washed with DMF, acetone three times in turn. The solid material was dried in a 60°C vacuum oven for 12 h to obtain white powder MOL.
[0052] Comparative Example 7
[0053] Preparation of UiO-66:
[0054] Synthesis of Fe-UiO-66: 40 mg of as-synthesized UiO-66 and 200 mg of FeCl3·6H2O were ultrasonically dispersed in 4 mL of MeCN. Stirring was carried out in an oil bath at 85 °C for 12 h. After cooling to room temperature, the solid was separated by centrifugation and washed with H2O and methanol to remove excess Fe.
[0055] Comparative Example 8
[0056] Synthesis of Fe-UiO-66:
[0057] Fe-UiO-66: 40 mg of as-synthesized UiO-66 and 200 mg of FeCl3·6H2O were ultrasonically dispersed in 4 mL of MeCN. Stirring was carried out in an oil bath at 85 °C for 12 h. After cooling to room temperature, the solid was separated by centrifugation and washed with H2O and methanol to remove excess Fe 3+ . As-synthesized Fe-UiO-66 was obtained by drying under vacuum at 60 °C.
[0058] Comparative Example 9
[0059] Fe2O3 was directly mixed with MOL at a loading of 3.81 wt% Fe.
[0060] Comparative Example 10
[0061] FeCl3·6H2O was directly used as catalyst.
[0062] The results of the photocatalytic oxidation of toluene for the samples prepared in Comparative Examples 6-10 are shown in Table 3:
[0063] Table 3 Results of photocatalytic oxidation of toluene for samples prepared in Comparative Examples 6-10
[0064]
[0065] As can be seen from Table 3, the pure MOL material has no obvious catalytic activity. By way of comparison, as-synthesized UiO-66 and Fe-modified UiO-66 were synthesized, and it can be found that the catalytic performance of Example 1 is much higher than that of Fe-UiO-66. Meanwhile, physical mixing of Fe2O3 and MOL also has no obvious catalytic activity. Catalytic experiments using FeCl3·6H2O alone also have no obvious catalytic activity.
[0066] The sample prepared in Example 1 was used to test toluene derivatives with other substituents, and the results are shown in Table 4:
[0067] Table 4 Results of photocatalytic oxidation of toluene derivatives for the sample prepared in Example 1
[0068]
[0069]
[0070] Note: Reaction conditions: 47.2 μmol substrate, 1 mL acetonitrile, 20 μL H2O, 5 mg Fe-MOL-200-16 as photocatalyst, λ≥320 nm, O21 atm, reaction time 3 h.
[0071] like Figure 1 As shown, (a) is a nanosheet of MOL with a thickness of about 4 nm; (b) is an ultrathin nanosheet of Fe-MOL-200-16 prepared in Example 1, indicating that the morphology of MOL was not changed after the post-modification.
[0072] like Figure 2 As shown, the X-ray photoelectron spectroscopy spectrum of Fe2-MOL shows that the binding energy of Fe2p3 / 2 is 711.4 eV(a), which is typical for Fe. 3+ The signal indicates that no redox process occurred during the solvothermal process, and the peak value of Zr 3d5 / 2 shifted from 182.85 eV to a higher binding energy (b).
[0073] like Figure 3 As shown, the presence of Fe was verified by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). 3+ With -O / OH x Bonding between groups, of which 3670cm -1 The peak at that location is attributed to the terminal -OH / -OH2 and μ3-OH groups on the Zr6-oxo cluster, with the peak intensity at Fe 3+ The significant decrease after modification reveals the interaction between these groups and Fe. 3+ Interactions of ions.
[0074] like Figure 4 As shown, the steady-state photoluminescence spectrum under 340 nm excitation indicates that both MOF and Fe-MOL produce a broad wavelength band centered at approximately 450 nm, but with significantly different intensities, following the order MOL > Fe-MOL-200-16. The decrease in PL signal intensity in the composite material compared to MOF indicates a rapid transfer of electrons from Fe to MOL-200-16.
Claims
1. A heterogeneous metal Fe post-modified zirconium-based organic layer photocatalyst, characterized in that, The photocatalyst takes a zirconium-based organic layer Zr-MOL as a carrier, and a heterometal Fe is introduced after Zr-O clusters 3+ The loading amount of the Fe 3+ is 3.6-4wt%, and the atomic ratio of Zr and Fe is 6:2.3-2.
7.
2. The method for producing a photocatalyst according to claim 1, characterized by, First, Zr-MOL layered structure is assembled by solvothermal method, then Fe is introduced by impregnation method with Zr-MOL as carrier 3+ , and Fe / Zr-MOL is prepared after solid-liquid separation, washing and drying.
3. The preparation method according to claim 2, characterized in that, The specific process of the solvothermal method is that the zirconium-based precursor is dissolved in DMF and acetic acid, mixed thoroughly, and then reacted at 70-100 DEG C for 1-3 hours; then 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine is added, and the reaction is continued at 110-130 DEG C for 1-3 hours.
4. The production method according to claim 3, characterized by, The zirconium-based precursor is zirconium oxychloride octahydrate, and the volume ratio of DMF to acetic acid is 3:
2.
5. The preparation method according to claim 2, characterized in that, The specific process of the impregnation method is that Zr-MOL is added to an acetonitrile solution of FeCl3·6H2O, ultrasonically dispersed, and then stirred and reacted at 70-90 DEG C for 14-18 hours.
6. Use of the photocatalyst according to claim 1 or of the photocatalyst prepared according to any one of claims 2 to 5, characterized in that, It is used for photocatalytic oxidation of toluene and derivatives thereof.