Defective uiO-66(zr) nanocatalyst, method for preparing the same, and use thereof
By introducing an acid regulator and reflux elution process into the UiO-66(Zr) nanocatalyst, the problems of poor acid-base site synergy and limited preparation scale in traditional methods were solved, achieving efficient furfural conversion and furfuryl alcohol selectivity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TIANJIN UNIV
- Filing Date
- 2026-03-02
- Publication Date
- 2026-06-05
Smart Images
Figure CN122141764A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the fields of biomass catalytic conversion and metal-organic framework materials, and particularly to a defective UiO-66(Zr) nanocatalyst, its preparation method, and its application. Background Technology
[0002] Furfuryl alcohol is an important biomass platform molecule with wide applications in synthetic chemistry, materials chemistry, and biomedicine. Currently, industrial applications primarily utilize heterogeneous metal catalysts to directly hydrogenate biomass-derived furfural into furfuryl alcohol. This process typically requires high temperature and pressure conditions, resulting in high energy consumption, catalyst deactivation, and environmental concerns.
[0003] In recent years, heterogeneous catalytic transfer hydrogenation technology has attracted attention due to its mild operating conditions and environmental friendliness. Catalytic transfer hydrogenation uses alcohols (such as isopropanol) as the hydrogen source, achieving the conversion of furfural to furfuryl alcohol via the Meerwein-Ponndorf-Verley reduction mechanism. Metal-organic frameworks (such as UiO-66(Zr)) are structurally tunable and highly stable metal-organic frameworks that show potential in catalytic transfer hydrogenation reactions because they can simultaneously provide abundant Lewis acid sites (from unsaturated coordinated zirconium metal centers) and Lewis base sites (from oxygen species or hydroxyl groups within the framework). However, UiO-66(Zr) materials prepared by conventional methods have the following limitations: firstly, the ratio and spatial distribution of Lewis acid and Lewis base sites are difficult to control precisely; secondly, the synthesis scale is limited, making gram-level preparation difficult; and thirdly, effective synergy of acid and base sites is difficult to achieve in furfural transfer hydrogenation reactions. Summary of the Invention
[0004] The purpose of this invention is to provide a defective UiO-66(Zr) nanocatalyst, its preparation method, and its application, in order to solve the problems of poor acid-base site synergy, low catalytic efficiency, and difficulty in achieving gram-scale preparation of UiO-66(Zr) materials prepared by traditional methods in the furfural transfer hydrogenation reaction.
[0005] To achieve the above objectives, the present invention provides a method for preparing defective UiO-66(Zr) nanocatalysts, comprising the following steps: S1. Zirconium chloride, terephthalic acid and acid modifier are added to N,N-dimethylformamide and subjected to a solvothermal reaction at 120-160℃ for 3-5 hours. After centrifugation, washing and drying, the defect precursor material is obtained. S2. The defect precursor material was dispersed in an organic solution and refluxed for elution. After centrifugation, washing and drying, defect-type UiO-66(Zr) nanocatalyst was obtained.
[0006] If zirconium chloride and terephthalic acid are added to N,N-dimethylformamide and subjected to a solvothermal reaction at 120-160℃ for 3-5 hours, followed by centrifugation, washing, and drying, defect-free UiO-66 is obtained. This invention uses zirconium chloride as a metal precursor and terephthalic acid as the main organic linker. By introducing an acid regulator and utilizing its competitive coordination, structural defects and active sites are pre-defined in the framework. Furthermore, by removing the unstable acid regulator, more Lewis acid-base sites are exposed and stabilized.
[0007] Preferably, the molar ratio of zirconium chloride, terephthalic acid and acid regulator is 1:(0.4-0.6):(0.6-0.4), and the molar ratio of terephthalic acid to acid regulator is 1:(0.9-1.1).
[0008] Preferably, the amount of zirconium chloride fed is 10-12 mmol; and the volume of N,N-dimethylformamide is 16-24 mL when the amount of zirconium chloride fed is 1 mmol.
[0009] Preferably, the acid regulator is one of benzoic acid and acetic acid. The acidity coefficient and molecular size of the acid regulator introduced in this invention are key factors affecting the initial defect structure and final performance.
[0010] Preferably, the acid regulator is benzoic acid.
[0011] Preferably, the organic solvent is a mixed solution of hydrochloric acid and N,N-dimethylformamide; the volume ratio of hydrochloric acid to N,N-dimethylformamide is 1:200; and the hydrochloric acid is of analytical grade with a mass fraction standard concentration of 36-38%.
[0012] Preferably, the reflux elution is repeated 2-4 times; the reflux elution temperature is 80-100℃ and the time is 24h.
[0013] Preferably, the reflux elution is repeated three times. The number of reflux elution repetitions in this invention allows for precise control of the final defect density and surface properties of the catalyst.
[0014] This invention provides a defective UiO-66(Zr) nanocatalyst, which is prepared by the above-mentioned method for preparing a defective UiO-66(Zr) nanocatalyst.
[0015] This invention also provides an application of a defective UiO-66(Zr) nanocatalyst, specifically its application in the catalytic transfer hydrogenation reaction of furfural; the hydrogen donor for the transfer hydrogenation reaction is isopropanol, the reaction temperature is 140-160℃, and the reaction time is 2-6h.
[0016] In summary, the defective UiO-66(Zr) nanocatalyst, its preparation method, and its application provided by this invention offer the following advantages compared to traditional technologies: (1) The present invention uses an acid regulator to pre-determine the initial defect structure, and then uses subsequent reflux elution to achieve precise construction of the final defect density, thus preparing a defective UiO-66(Zr) nanocatalyst. Furthermore, through the synergistic effect of the combination of acid regulator type screening and reflux elution process, the ratio and spatial distribution of Lewis acid and Lewis base sites in the defective UiO-66(Zr) nanocatalyst are finely controlled at the molecular level, thereby achieving excellent synergistic catalysis and significantly improving reaction efficiency.
[0017] (2) The present invention has determined the optimal process conditions for benzoic acid to be combined with three reflux elution, which plays an important role in achieving a near 100% comprehensive catalytic performance of defective UiO-66(Zr) nanocatalyst.
[0018] (3) The method of the present invention breaks through the limitation of small-scale traditional synthesis. Using zirconium chloride as a precursor, it stably realizes the gram-scale preparation of defective UiO-66(Zr) nanocatalysts.
[0019] (4) The defective UiO-66(Zr) nanocatalyst prepared by the present invention can achieve 100% furfural conversion and 99.5% furfuryl alcohol selectivity, and its performance is significantly better than that of traditional UiO-66(Zr) nanocatalyst.
[0020] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description
[0021] Figure 1 Scanning electron microscope images of defect-free UiO-66 prepared for Comparative Example 1 at different scales; Figure 1 Part (a) in the image is a scanning electron microscope image of defect-free UiO-66 with a scale bar of 2 μm; Figure 1 Part (b) is a scanning electron microscope image of defect-free UiO-66 with a scale bar of 500 nm; Figure 2 The image shows scanning electron microscope images of the low defect density UiO-66 (denoted as UiO-66-BA-L) prepared by benzoic acid regulator in Comparative Example 2 at different scales. Figure 2 Part (a) in the image is a scanning electron microscope image of UiO-66-BA-L with a scale bar of 2 μm; Figure 2 Part (b) is a scanning electron microscope image of UiO-66-BA-L with a scale bar of 500 nm; Figure 3SEM images of the medium defect density UiO-66 (denoted as UiO-66-BA-M) prepared by benzoic acid modifier in Comparative Example 3 at different scales; Figure 3 Part (a) in the image is a scanning electron microscope image of UiO-66-BA-M with a scale bar of 2 μm; Figure 3 Part (b) is a scanning electron microscope image of UiO-66-BA-M with a scale bar of 500 nm; Figure 4 Scanning electron microscope images of the high defect density UiO-66 (denoted as UiO-66-BA-H) based on benzoic acid modifier prepared in Example 1 at different scales; Figure 4 Part (a) in the image is a scanning electron microscope image of UiO-66-BA-H with a scale bar of 2 μm; Figure 4 Part (b) is a scanning electron microscope image of UiO-66-BA-H with a scale bar of 500 nm; Figure 5 Scanning electron microscope images of the high defect density UiO-66 (denoted as UiO-66-AA-H) based on acetic acid regulator prepared in Example 2 at different scales; Figure 5 Part (a) in the image is a scanning electron microscope image of UiO-66-AA-H with a scale bar of 2 μm; Figure 5 Part (b) is a scanning electron microscope image of UiO-66-AA-H with a scale bar of 500 nm; Figure 6 Powder X-ray diffraction images of defect-free UiO-66 prepared in Comparative Example 1, UiO-66-BA-L prepared in Comparative Example 2, UiO-66-BA-M prepared in Comparative Example 3, and UiO-66-BA-H prepared in Example 1. Detailed Implementation
[0022] The technical method of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specifically stated, the relative arrangement and numerical values of the steps in these embodiments do not limit the scope of this application. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application or its application or use.
[0023] In the embodiments, all original reagent materials are commercially available. Experimental methods not specifically described are conventional methods and conditions well-known in the art, or are performed according to the conditions recommended by the instrument manufacturer. Unless otherwise defined, the technical or scientific terms used in this invention should be understood in their ordinary sense by one of ordinary skill in the art.
[0024] Example 1 A gram-scale preparation method for defective UiO-66(Zr) nanocatalysts, comprising the following steps: S1. Weigh 2.328 g (i.e., 10 mmol) of zirconium chloride and 0.84 g (i.e., 5 mmol) of terephthalic acid and dissolve them in 100 mL of N,N-dimethylformamide. Stir vigorously at room temperature for 10 min until fully dissolved. Then add 0.61 g (i.e., 5 mmol) of benzoic acid and continue stirring vigorously for 20 min to obtain a homogeneous solution. Then transfer the homogeneous solution to a high-pressure reactor lined with polytetrafluoroethylene and crystallize at 140 °C for 24 h. After the solvothermal reaction is completed, centrifuge to collect the white precipitate, wash it three times with N,N-dimethylformamide, and dry it to obtain the defect precursor material.
[0025] S2. Disperse the defect precursor material in a mixed solution of 0.4 mL hydrochloric acid (analytical purity, mass fraction standard concentration of 36-38%) and 80 mL N,N-dimethylformamide, reflux at 90 °C for 24 h for elution and activation, repeat the reflux elution process 3 times to construct a high defect density material, and collect the solid by centrifugation after each elution to obtain the crude product.
[0026] S3. The crude product was washed twice, first with N,N-dimethylformamide and then with methanol, respectively. It was then dispersed in 80 mL of methanol and refluxed at 90 °C for 24 h. This reflux process was repeated twice to completely remove residual N,N-dimethylformamide. The product was then dried overnight in a vacuum oven at 70 °C to obtain the UiO-66-BA-H catalyst with high defect density based on benzoic acid as a modifier. Scanning electron micrographs at different scales are shown below. Figure 4 As shown, its powder X-ray diffraction pattern is as follows: Figure 6 As shown.
[0027] Example 2 A gram-scale preparation method for defective UiO-66(Zr) nanocatalysts, comprising the following steps: S1. Weigh 2.328 g (10 mmol) of zirconium chloride and 0.84 g (5 mmol) of terephthalic acid and dissolve them in 100 mL of N,N-dimethylformamide. Stir vigorously at room temperature for 10 min until fully dissolved. Then add 0.288 mL (5 mmol) of acetic acid and continue stirring vigorously for 20 min to obtain a homogeneous solution. Transfer the homogeneous solution to a high-pressure reactor lined with polytetrafluoroethylene and crystallize at 140 °C for 24 h. After the solvothermal reaction is completed, centrifuge to collect the white precipitate, wash it three times with N,N-dimethylformamide, and dry it to obtain the defect precursor material.
[0028] S2. Disperse the defect precursor material in a mixed solution of 0.4 mL hydrochloric acid (analytical purity, mass fraction standard concentration of 36%-38%) and 80 mL N,N-dimethylformamide, reflux at 90 °C for 24 h for elution and activation, repeat the reflux elution process 3 times to construct a high defect density material, and collect the solid by centrifugation after each elution to obtain the crude product.
[0029] S3. The crude product was washed twice, successively with N,N-dimethylformamide and methanol, and then dispersed in 80 mL of methanol and refluxed at 90 °C for 24 h. The reflux process was repeated twice to completely remove residual N,N-dimethylformamide. The product was then dried overnight in a vacuum drying oven at 70 °C to obtain the UiO-66-AA-H catalyst with high defect density based on acetic acid regulator. Scanning electron micrographs at different scales are shown below. Figure 5 As shown.
[0030] Comparative Example 1 A method for preparing UiO-66(Zr) nanocatalyst, comprising the following steps: S1. Weigh 2.328 g (10 mmol) of zirconium chloride and 1.68 g (10 mmol) of terephthalic acid and dissolve them in 100 mL of N,N-dimethylformamide. Stir vigorously at room temperature for 10 min until fully dissolved to obtain a homogeneous solution. Then, transfer the homogeneous solution to a high-pressure reactor lined with polytetrafluoroethylene and crystallize at 140 °C for 24 h. After the solvothermal reaction is complete, collect the white precipitate by centrifugation, wash it three times with N,N-dimethylformamide, and dry it overnight in a vacuum drying oven at 70 °C to obtain a defect-free UiO-66 nanocatalyst. The scanning electron microscope images of the nanocatalyst at different scales are shown below. Figure 1 As shown, its powder X-ray diffraction pattern is as follows: Figure 6 As shown.
[0031] Comparative Example 2 A method for preparing UiO-66(Zr) nanocatalyst, comprising the following steps: S1. Weigh 2.328 g (i.e., 10 mmol) of zirconium chloride and 0.84 g (i.e., 5 mmol) of terephthalic acid and dissolve them in 100 mL of N,N-dimethylformamide. Stir vigorously at room temperature for 10 min until fully dissolved. Then add 0.61 g (i.e., 5 mmol) of benzoic acid and continue stirring vigorously for 20 min to obtain a homogeneous solution. Then transfer the homogeneous solution to a high-pressure reactor lined with polytetrafluoroethylene and crystallize at 140 °C for 24 h. After the solvothermal reaction is completed, centrifuge to collect the white precipitate, wash it three times with N,N-dimethylformamide, and dry it to obtain the defect precursor material.
[0032] S2. The defect precursor material was washed twice, sequentially with N,N-dimethylformamide and methanol, respectively. It was then dispersed in 80 mL of methanol and refluxed at 90 °C for 24 h. This reflux process was repeated twice to completely remove residual N,N-dimethylformamide. Finally, it was dried overnight in a vacuum oven at 70 °C to obtain a UiO-66-BA-L catalyst with low defect density based on benzoic acid as a modifier. Scanning electron microscopy images at different scales are shown below. Figure 2 As shown, its powder X-ray diffraction pattern is as follows: Figure 6 As shown.
[0033] Comparative Example 3 A method for preparing UiO-66(Zr) nanocatalyst, comprising the following steps: S1. Weigh 2.328 g (i.e., 10 mmol) of zirconium chloride and 0.84 g (i.e., 5 mmol) of terephthalic acid and dissolve them in 100 mL of N,N-dimethylformamide. Stir vigorously at room temperature for 10 min until fully dissolved. Then add 0.61 g (i.e., 5 mmol) of benzoic acid and continue stirring vigorously for 20 min to obtain a homogeneous solution. Then transfer the homogeneous solution to a high-pressure reactor lined with polytetrafluoroethylene and crystallize at 140 °C for 24 h. After the solvothermal reaction is completed, centrifuge to collect the white precipitate, wash it three times with N,N-dimethylformamide, and dry it to obtain the defect precursor material.
[0034] S2. Disperse the defect precursor material in a mixed solution of 0.4 mL hydrochloric acid (analytical purity, mass fraction standard concentration of 36%-38%) and 80 mL N,N-dimethylformamide, reflux at 90 °C for 24 h for one elution activation to construct a medium defect density material, collect the solid by centrifugation to obtain the crude product.
[0035] S3. The crude product was washed twice, successively with N,N-dimethylformamide and methanol, and then dispersed in 80 mL of methanol and refluxed at 90 °C for 24 h. The reflux process was repeated twice to completely remove residual N,N-dimethylformamide. The product was then dried overnight in a vacuum drying oven at 70 °C to obtain a UiO-66-BA-M catalyst with moderate defect density based on benzoic acid as a modifier. Scanning electron micrographs at different scales are shown below. Figure 3 As shown, its powder X-ray diffraction pattern is as follows: Figure 6 As shown.
[0036] like Figure 1 Part (a) and Figure 1 As shown in part (b) of the figure, the defect-free UiO-66 catalyst prepared in Comparative Example 1 exhibits a clear and regular octahedral structure with distinct edges and a smooth surface. Figure 1 respectively with Figure 2 , Figure 3 and Figure 4In comparison, it can be seen that the surface morphology of the catalyst after the addition of benzoic acid as a modifier begins to become rough, and the particle size also changes significantly. Figure 2 Part (a) and Figure 2 Part (b) in the figure is a scanning electron microscope image of the UiO-66-BA-L catalyst prepared by adding benzoic acid to Comparative Example 2 without elution. Figure 1 compared to, Figure 2 A sea urchin-like morphology was observed, the inherent structural framework was disrupted, and particle aggregation was more pronounced, hindering the diffusion of reactants to the catalyst active site and the diffusion of products from the active site. (Comparison) Figure 2 Part (a) of the text Figure 2 Part (b) of the text Figure 3 Part (a) of the text Figure 3 Part (b) of the text Figure 4 Part (a) and Figure 4 As can be seen in part (b), by eluting the benzoic acid modifier, the dispersion of UiO-66(Zr) nanocatalyst gradually increases. While achieving high dispersion, the particle size of the catalyst also gradually decreases, which helps to improve the catalytic activity of the catalyst.
[0037] according to Figure 4 Part (a) of the text Figure 4 Part (b) of the text Figure 5 Part (a) and Figure 5 As shown in section (b), the UiO-66-BA-H prepared in Example 1 exhibits good dispersibility on a large scale, and small-sized spherical aggregates can be observed under magnification. The UiO-66-AA-H prepared in Example 2 shows reduced dispersibility and more angular features. Magnified images reveal a rough, rod-like morphology. This is because the competitive coordination of acetic acid and terephthalic acid at the zirconium nodes inhibits crystal nucleation and accelerates its growth. Simultaneously, because the alkyl chain length of the benzoic acid modifier is longer than that of acetic acid, UiO-66-BA-H exhibits a more pronounced rough surface morphology, which facilitates the contact and reaction between the nanocatalyst and the reaction substrate.
[0038] Figure 6 Powder X-ray diffraction images of the nanocatalysts prepared in Comparative Examples 1, 2, 3, and 1. According to... Figure 6It was found that all four catalysts (defect-free UiO-66, UiO-66-BA-L, UiO-66-BA-M, and UiO-66-BA-H) exhibited characteristic diffraction peaks of UiO-66(Zr), confirming the successful synthesis of the catalysts. Compared with the defect-free UiO-66 prepared without the addition of acid modifier, the diffraction peak positions of UiO-66-BA-L, UiO-66-BA-M, and UiO-66-BA-H did not change, indicating that the addition of benzoic acid modifier does not affect the crystal structure of the catalyst. However, with the increase of elution times, the diffraction peak intensity gradually increased, indicating that the number of reflux elution times with acid modifier affects the degree of crystallinity of the catalyst, and thus affects the defect density.
[0039] The catalytic performance of Examples 1, 2, 1, 2, and 3 was evaluated, and the specific procedures were as follows: In a 25 mL high-pressure reactor, 100 mg of catalyst, 120 mmol of furfural, 9.4 mL of isopropanol and 0.5 mL of n-dodecane (internal standard) were added. The transfer hydrogenation reaction was carried out at 140 °C and stirred at 800 rpm for 4 h. After the reaction was completed, the mixture was cooled to room temperature, centrifuged and the supernatant was collected. The composition of the product was analyzed by gas chromatography, and the furfural conversion rate, furfuryl alcohol selectivity and furfuryl alcohol yield were calculated. The results are shown in Table 1.
[0040] Table 1. Catalytic performance of catalysts prepared in the examples and comparative examples.
[0041] As shown in Table 1, the defect-free UiO-66 nanocatalyst prepared in Comparative Example 1 has the lowest catalytic performance, proving that the inherent acid-base synergistic effect of the traditional UiO-66(Zr) nanocatalyst is limited.
[0042] Examples 1 and 2 significantly demonstrate the necessity of screening acid modifier types. Although both Examples 1 and 2 underwent three reflux elutions during preparation, the catalytic performance of the resulting catalysts differed significantly, with UiO-66-BA-H > UiO-66-AA-H. This indicates that benzoic acid has a unique and optimal effect in constructing a system with the best Lewis acid and Lewis base site ratio and spatial configuration, and its molecular size and acidity coefficient are most well-matched to the synthetic system.
[0043] Comparative Examples 2 and 3, along with Example 1, demonstrate that the catalytic performance significantly improves with increasing reflux elution cycles, proving that the reflux elution process plays a decisive role in constructing highly active catalytic materials.
[0044] Based on the catalytic performance data, the UiO-66-BA-H prepared in Example 1 of this invention achieved a conversion rate of 100% and a selectivity of 99.5%, which fully verified the effectiveness of the process combining acid regulator screening and reflux elution. It also showed that under the optimal preparation process in Example 1, the Lewis acid and Lewis base sites of the UiO-66-BA-H catalyst reached the best synergistic state.
[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.
Claims
1. A method for preparing a defective UiO-66(Zr) nanocatalyst, characterized in that, Includes the following steps: S1. Zirconium chloride, terephthalic acid and acid modifier are added to N,N-dimethylformamide and subjected to a solvothermal reaction at 120-160℃ for 3-5 hours. After centrifugation, washing and drying, the defect precursor material is obtained. S2. The defect precursor material was dispersed in an organic solution and refluxed for elution. After centrifugation, washing and drying, defect-type UiO-66(Zr) nanocatalyst was obtained.
2. The method for preparing a defective UiO-66(Zr) nanocatalyst according to claim 1, characterized in that, The molar ratio of zirconium chloride, terephthalic acid, and acid regulator is 1:(0.4~0.6):(0.6~0.4), and the molar ratio of terephthalic acid to acid regulator is 1:
1.
3. The method for preparing a defective UiO-66(Zr) nanocatalyst according to claim 1, characterized in that, The amount of zirconium chloride fed is 10-12 mmol; the volume of N,N-dimethylformamide is 16-24 mL when the amount of zirconium chloride fed is 1 mmol.
4. The method for preparing a defective UiO-66(Zr) nanocatalyst according to claim 2, characterized in that, The acid regulator is either benzoic acid or acetic acid.
5. The method for preparing a defective UiO-66(Zr) nanocatalyst according to claim 4, characterized in that, The acid regulator is benzoic acid.
6. The method for preparing a defective UiO-66(Zr) nanocatalyst according to claim 1, characterized in that, The organic solvent is a mixed solution of hydrochloric acid and N,N-dimethylformamide; the volume ratio of hydrochloric acid to N,N-dimethylformamide is 1:200; the hydrochloric acid is of analytical grade and has a mass fraction standard concentration of 36-38%.
7. The method for preparing a defective UiO-66(Zr) nanocatalyst according to claim 1, characterized in that, The reflux elution is repeated 2-4 times; the reflux elution temperature is 80-100℃ and the time is 24h.
8. The method for preparing a defective UiO-66(Zr) nanocatalyst according to claim 1, characterized in that, The reflux elution was repeated three times.
9. A defective UiO-66(Zr) nanocatalyst, characterized in that, It is prepared by any one of the defective UiO-66(Zr) nanocatalysts according to any one of claims 1-8.
10. The application of a defective UiO-66(Zr) nanocatalyst, characterized in that, The application of the defective UiO-66(Zr) nanocatalyst of claim 9 in the catalytic transfer hydrogenation reaction of furfural; wherein the hydrogen donor of the transfer hydrogenation reaction is isopropanol, the reaction temperature is 140-160℃, and the reaction time is 2-6h.