Hafnium-based coordination polymer catalyst, preparation method thereof and application of hafnium-based coordination polymer catalyst in preparation of vanillyl alcohol ether

Abstract

The invention discloses a hafnium-based coordination polymer catalyst and a preparation method and application thereof in preparation of vanillyl alcohol ether.The catalyst is a coordination polymer composed of hafnium salt and a nitrogen-containing organic acid ligand, and the coordination polymer has a Lewis acid-base site and a # imgabs0 # acid site at the same time; the Lewis acid-base site is Hf < 4 + >-O < 2-> formed by hafnium and a nitrogen-containing organic acid group through a coordinate bond; and the # imgabs 1 # acidic site is-PO3H, and / or-COOH, and / or-OH, which do not participate in coordination, on the ligand. By changing the types of hafnium metal and organic ligands and the usage amount of hafnium ions and organic ligands, the density and strength of total acid-base sites of the catalyst and the proportion of # imgabs2 acid sites are adjusted, then the reaction path of vanillin one-pot reductive etherification is controlled, efficient directional synthesis of various vanillyl alcohol ethers is achieved in different alcohol endogenous hydrogen systems, and the method is suitable for industrial production. And the catalyst shows excellent catalytic stability and catalytic universality.

Description

Technical Field

[0001] The invention relates to a hafnium-based coordination polymer catalyst, a preparation method thereof and application thereof in preparing vanillin alcohol ether, belonging to the technical field of catalyst preparation and application. Background Art

[0002] As we all know, biomass is the only renewable resource containing carbon in nature. It has the characteristics of wide sources, rich varieties, huge reserves and low prices. Its effective conversion and utilization has extremely far-reaching significance for reducing environmental pollution and alleviating energy crises. In recent years, vanillin obtained by directional conversion of biomass component-lignin as raw material is a very important platform compound, because it can be used as a reactant to prepare various high-value-added chemicals, such as vanillin, vanillin ether and 4-methylguaiacol. Among them, vanillin ether obtained by hydrogenation reduction and dehydration etherification of vanillin is considered to be a new type of multifunctional chemical, which can be used as flavors, fragrances and oil-soluble heat-sensitive agents, etc., and is widely used in food, medicine, cosmetics and organic synthesis fields, and has broad market prospects.

[0003] As we all know, vanillin molecules contain an aldehyde group, a phenolic hydroxyl group, a methoxy group and a benzene ring, which makes its chemical properties very active. How to control the reactivity and reaction process of different reactive groups is the primary problem that needs to be solved in the process of directional and selective preparation of vanillin alcohol ether from vanillin, and the development of a suitable catalytic reaction system plays a vital role in solving this problem. At present, the catalytic preparation system of vanillin alcohol ether can be roughly divided into two categories: an exogenous hydrogen two-step preparation system and an alcohol endogenous hydrogen one-pot preparation system. Among them, the exogenous hydrogen two-step preparation system is the most typical and commonly used preparation system for vanillin alcohol ether, which is usually composed of hydrogen, a noble metal hydrogenation reduction catalyst and an acidic dehydration etherification catalyst. However, this system still has the disadvantages of large safety hazards of hydrogen donors, high cost of catalyst raw materials, numerous side reaction types and low selectivity of target products, which seriously restricts the production and application of vanillin alcohol ether.

[0004] Compared with the two-step preparation system with exogenous hydrogen, the alcohol endogenous hydrogen system can couple the Meerwein-Ponndorf-Verley (MPV) transfer hydrogenation reduction reaction of vanillin and the dehydration etherification reaction of vanillin alcohol, thereby realizing the synthesis of vanillin alcohol ether in a one-pot method without the use of precious metals and exogenous hydrogen. However, it should be pointed out that the MPV transfer hydrogenation reduction reaction of vanillin and the dehydration etherification reaction of vanillin alcohol require different Lewis acid-base sites and Acidic sites, and Lewis acid-base sites and The properties such as the content, proportion and strength of acidic sites will also affect the priority order of transfer hydrogenation reduction reaction and dehydration etherification reaction, and then affect the reaction degree, reaction rate and product distribution of the entire one-pot reduction etherification reaction pathway, and ultimately affect the synthesis of vanillin alcohol ether.

[0005] Therefore, designing and constructing a suitable acid-base bifunctional catalyst and regulating the properties of its acid-base sites are the premise and basis for achieving the directional and selective synthesis of vanillin alcohol ethers in a one-pot preparation system of endogenous hydrogen from alcohols. Summary of the invention

[0006] In order to solve the problems of large safety hazards of hydrogen donors, discontinuous separation of two-step reactions and low selectivity of target products in existing exogenous hydrogen preparation systems, and difficult control of one-pot reaction paths, low reaction activity of acid-base catalysts and poor universality in existing endogenous hydrogen preparation systems, the present invention provides a novel catalyst having both Lewis acid-base sites and Hafnium-based coordination polymer catalysts with acidic sites can precisely change the Lewis acidic and basic sites and The catalytic order and catalytic activity of the acidic sites can control the conversion path and reaction degree of vanillin, and ultimately achieve the directional and selective synthesis of a variety of vanillin ethers in different alcohol systems.

[0007] The technical solution adopted by the present invention is:

[0008] A hafnium-based coordination polymer catalyst, the catalyst is a coordination polymer composed of a hafnium salt and a nitrogen-containing organic acid ligand, and the coordination polymer has Lewis acid-base sites and Acidic sites;

[0009] The Lewis acid-base site is a Hf-type site formed by coordination bonds between hafnium and organic acid groups. 4+ -O 2- ; Acidic sites are -PO groups on the ligand that are not involved in coordination. 3 H, and / or -COOH, and / or -OH.

[0010] The preparation method of the hafnium-based coordination polymer catalyst is to mix a solution containing hafnium salt and nitrogen-containing organic acid ligand, add a deprotonating agent to react, and after the reaction is completed, let it stand for aging, and then separate, wash, and dry (it can be ground after drying).

[0011] Preferably, the hafnium salt is any one of hafnium tetrachloride, hafnium dichloride and hafnium acetylacetonate;

[0012] The nitrogen-containing organic acid ligand is any one of 2,5-pyridinedicarboxylic acid, cyanuric acid, citrazinic acid, iminodiacetic acid and aminotri(methylenephosphonic) acid;

[0013] The deprotonating agent was triethylamine.

[0014] Preferably, in the solution containing the hafnium salt, the concentration of the hafnium salt is 10-50 mmol / L;

[0015] The molar ratio of the hafnium salt, the nitrogen-containing organic acid ligand and the deprotonating agent is 3:(1-4):(12-36).

[0016] Preferably, the reaction conditions are: stirring at room temperature for 6-24 hours; and the static aging conditions are: 60-100° C. for 1-8 hours.

[0017] The hafnium-based coordination polymer catalyst is used in the one-pot method for preparing vanillin alcohol ether.

[0018] Preferably, the application is to heat and react the mixture of the hafnium-based coordination polymer catalyst, low-carbon alcohol and vanillin under a nitrogen atmosphere.

[0019] Preferably, the low-carbon alcohol is any one of ethanol, n-propanol, isopropanol, n-butanol and sec-butanol.

[0020] Preferably, the amount of vanillin is 1-3 wt% of the amount of the low-carbon alcohol, and the amount of the hafnium-based coordination polymer catalyst is 10-100 wt% of the amount of the vanillin.

[0021] Preferably, the heating reaction conditions are: 100-180° C., 1-10 h.

[0022] The beneficial effects of the present invention are:

[0023] By means of the “solvothermal self-assembly” strategy, Lewis acid-base sites (Hf 4+ -O 2- ), while the -PO on the organic acid ligand that does not participate in the coordination 3 H, -COOH or -OH becomes Acidic sites: By changing the types of hafnium salts and organic acid ligands and the amounts of hafnium ions and organic acid ligands used, the density, strength and Lewis / The acid site ratio is controlled, and then the MPV transfer hydrogenation reduction reaction of vanillin is controlled first, and the generated vanillin continues to undergo dehydration etherification reaction, which not only avoids the occurrence of side reactions such as acetalization, but also promotes the directional and selective synthesis of vanillin ether; the hafnium-based coordination polymer catalyst shows excellent catalytic stability and catalytic universality. It can not only be reused, but also catalyze vanillin to generate corresponding vanillin ether in different alcohols; the reaction system is simple, does not require exogenous hydrogen, has a high safety factor, and is easy to scale up and promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 SEM spectrum (A) and XRD (B) of Hf-MM prepared in Comparative Example 1;

[0025] Figure 2 FT-IR spectrum of Hf-MM prepared in Comparative Example 1;

[0026] Figure 3 SEM spectrum (A) and XRD (B) of Hf-DHIA prepared in Example 1;

[0027] Figure 4 FT-IR spectrum of Hf-DHIA prepared in Example 1;

[0028] Figure 5 SEM spectrum (A) and XRD (B) of Hf-NTPA-1 prepared in Example 2;

[0029] Figure 6 FT-IR spectrum of Hf-NTPA-1 prepared in Example 2;

[0030] Figure 7 This is the GC chromatogram of the one-pot preparation of vanillin ethyl ether catalyzed by Hf-NTPA-1 in Example 4. DETAILED DESCRIPTION

[0031] This application uses the "solvothermal self-assembly" strategy to prepare a novel nanostructured ... Hafnium-based coordination polymer catalysts with acidic sites and by regulating Lewis acidic and basic sites and The catalytic order and catalytic activity of the acidic sites can then control the directional selective conversion path of vanillin, and ultimately achieve a one-pot synthesis of different vanillin ethers in a low-carbon alcohol system. 4+ -O 2- It is the Lewis acid-base site, which is mainly responsible for promoting the MPV transfer hydrogenation reaction of vanillin to synthesize vanillyl alcohol; the -PO 3 H, -COOH or -OH is Acidic site, which is mainly responsible for promoting the further dehydration and etherification of vanillyl alcohol into vanillyl alcohol ether.

[0032] Comparative Example 1

[0033] 15mmol hafnium tetrachloride was added to 400mL dimethylformamide, and 20mmol melamine was added to 200mL dimethylformamide at the same time, and stirred with the assistance of ultrasound until completely dissolved, and marked as solution A and solution B respectively; under stirring at room temperature, solution B was slowly added to solution A, and then 120mmol triethylamine was dropwise added to the AB mixture, and after stirring at room temperature for 12h, the temperature was raised to 90°C and allowed to stand for 4h; the solid precipitate was separated by filtration and repeatedly washed with dimethylformamide, ethanol and deionized water until the filtrate did not contain chloride ions; the washed solid precipitate was placed in a vacuum drying oven and dried at 80°C for 12h to obtain a hafnium-based coordination polymer catalyst, marked as Hf-MM.

[0034] The results of SEM and XRD analysis show that ( Figure 1 ): Hf-MM is composed of nanoparticles with rough surface and irregular morphology, belonging to an amorphous structure. FT-IR characterization analysis shows that ( Figure 2 ), 483cm -1 The stretching vibration peaks attributed to the Hf-N bond indicate that the Lewis acid sites (Hf 4+ -N 3- ).

[0035] 3408cm -1 The stretching vibration peaks are attributed to the NH bond, which indicates that there are -NH 2 groups, which are Lewis basic sites. 3 -TPD, CO 2 -TPD and Py-IR characterization analysis showed that the Lewis acidic site content of Hf-MM was 0.953mmol / g, and the Lewis basic site content was 1.711mmol / g. The acidic site content is 0.

[0036] Next, 0.25 g of vanillin, 20 g of ethanol and 0.1 g of Hf-MM were added to a 50 mL reactor. The reactor was sealed and the air in the reactor was replaced with nitrogen. The reactor was heated to 160 °C at a stirring speed of 400 rpm. After 3 h of reaction, the conversion rate of vanillin was 38.9%, and the yield and selectivity of vanillin ether were only 15.8% and 40.6%, respectively. This shows that Lewis acid-base sites can catalyze the synthesis of vanillin ether from vanillin by a one-pot method to a certain extent, but due to the lack of The acidic sites make the catalytic activity of the catalyst very limited.

[0037] Example 1

[0038] 15mmol hafnium tetrachloride was added to 400mL dimethylformamide, and 20mmol citrazinic acid was added to 200mL dimethylformamide, and stirred with the assistance of ultrasound until completely dissolved, and marked as solution A and solution B respectively; under stirring at room temperature, solution B was slowly added to solution A, and then 120mmol triethylamine was dropwise added to the AB mixture, and after stirring at room temperature for 12h, the temperature was raised to 90°C and allowed to stand for 4h; the solid precipitate was separated by filtration and repeatedly washed with dimethylformamide, ethanol and deionized water until the filtrate did not contain chloride ions; the washed solid precipitate was placed in a vacuum drying oven and dried at 80°C for 12h to obtain a hafnium-based coordination polymer catalyst, marked as Hf-DHIA.

[0039] The results of SEM and XRD analysis show that ( Figure 3 ): Hf-DHIA is composed of nanoparticles with rough surface and irregular morphology, and has an amorphous structure. FT-IR characterization analysis shows that ( Figure 4 ), 568cm -1 and 782cm -1 The stretching vibration peaks attributed to the Hf-O bond indicate that the Lewis acid sites (Hf 4+ -O 2- ). 3433cm -1 The stretching vibration peaks are attributed to the OH bond, which indicates that there are -COOH and -OH groups in Hf-DHIA that are not involved in the coordination. Acidic sites. In addition, 1321cm -1 It is attributed to the stretching vibration peak of the CN bond on the ligand in Hf-DHIA, and N is also a Lewis basic site. 3 -TPD, CO 2 -TPD and Py-IR characterization analysis showed that the Lewis acidic site content of Hf-DHIA was 0.759mmol / g, and the Lewis basic site content was 1.617mmol / g. The acidic site content is 0.593 mmol / g.

[0040] Next, 0.25 g of vanillin, 20 g of ethanol and 0.1 g of Hf-DHIA were added to a 50 mL reactor. The reactor was sealed and the air in the reactor was replaced with nitrogen. The reactor was heated to 160 ° C at a stirring speed of 400 rpm. After 3 h of reaction, the conversion rate of vanillin was 57.4%, and the yield and selectivity of vanillin ether were 50.7% and 88.3%, respectively. This shows that: compared with Control Example 1, although the Lewis acid-base site content of Hf-DHIA is lower than that of Hf-MM, due to the fact that Hf-DHIA contains a certain amount of Acidic sites can further promote the dehydration etherification step in the reaction process, thereby improving the catalytic activity of the catalyst.

[0041] Example 2

[0042] 15mmol hafnium tetrachloride was added to 400mL dimethylformamide, and 10mmol aminotri(methylenephosphonic acid) was added to 200mL dimethylformamide, and stirred with the assistance of ultrasound until completely dissolved, and they were marked as solution A and solution B respectively; under stirring at room temperature, solution B was slowly added to solution A, and then 120mmol triethylamine was dropwise added to the AB mixture, and after stirring at room temperature for 12h, the temperature was raised to 90°C and allowed to stand for 4h; the solid precipitate was separated by filtration and repeatedly washed with dimethylformamide, ethanol and deionized water until the filtrate did not contain chloride ions; the washed solid precipitate was placed in a vacuum drying oven and dried at 80°C for 12h to obtain a hafnium-based coordination polymer catalyst, marked as Hf-NTPA-1.

[0043] The results of SEM and XRD analysis show that ( Figure 5 ): Hf-NTPA-1 is composed of nanoparticles with rough surface and irregular morphology, and has an amorphous structure. FT-IR characterization analysis shows that ( Figure 6 ), 563cm -1 and 761cm -1 The stretching vibration peak attributed to the Hf-O bond is 1025 cm -1 The stretching vibration peaks attributed to the Hf-OP bond indicate that the Lewis acid sites (Hf 4+ -O 2- ). 2403cm -1 and 3423cm -1 The stretching vibration peaks are attributed to the OH bond on P-OH, which indicates that there are -PO 3 H groups, which are Acidic sites. In addition, 1325cm -1It is attributed to the stretching vibration peak of the CN bond on the ligand in Hf-NTPA-1, and N is also a Lewis basic site. 3 -TPD, CO 2 -TPD and Py-IR characterization analysis show that the Lewis acidic site content of Hf-NTPA-1 is 0.748mmol / g, and the Lewis basic site content is 1.523mmol / g. The acidic site content is 0.517 mmol / g.

[0044] Next, 0.25 g of vanillin, 20 g of ethanol and 0.1 g of Hf-NTPA-1 were added to a 50 mL reactor, and the reactor was sealed and the air in the reactor was replaced with nitrogen. The reactor was heated to 160 ° C at a stirring speed of 400 rpm. After 3 h of reaction, the conversion rate of vanillin was 70.5%, and the yield and selectivity of vanillin ether were 66.5% and 94.4%, respectively. This shows that compared with Example 1, although the Lewis acid-base site content and The acidic site content is lower than that in Hf-DHIA, but due to the The acidic site is -PO 3 The acidity of the H group is stronger than that of the -COOH and -OH groups in DHIA, which can be more conducive to the formation of vanillyl alcohol ether. In addition, the results of this example also show that the Lewis acid-base site and There is a good synergistic effect between the acidic sites, which together promote the one-pot conversion of vanillin to vanillyl alcohol ether.

[0045] Example 3

[0046] 15mmol hafnium tetrachloride was added to 400mL dimethylformamide, and 6mmol aminotri(methylenephosphonic acid) was added to 200mL dimethylformamide, and stirred with the assistance of ultrasound until completely dissolved, and they were marked as solution A and solution B respectively; under stirring at room temperature, solution B was slowly added to solution A, and then 120mmol triethylamine was dropwise added to the AB mixture, and after stirring at room temperature for 12h, the temperature was raised to 90°C and allowed to stand for 4h; the solid precipitate was separated by filtration and repeatedly washed with dimethylformamide, ethanol and deionized water until the filtrate did not contain chloride ions; the washed solid precipitate was placed in a vacuum drying oven and dried at 80°C for 12h to obtain a hafnium-based coordination polymer catalyst, marked as Hf-NTPA-2.

[0047] SEM and XRD analysis results show that Hf-NTPA-2 is composed of nanoparticles with rough surface and irregular morphology, and has an amorphous structure. FT-IR characterization analysis shows that 563cm-1 and 761cm -1 The stretching vibration peak attributed to the Hf-O bond is 1025 cm -1 The stretching vibration peaks attributed to the Hf-OP bond indicate that the Lewis acid sites (Hf 4+ -O 2- ). 2403cm -1 and 3423cm -1 The stretching vibration peaks are attributed to the OH bond on P-OH, which indicates that there are -PO 3 H groups, which are Acidic sites. In addition, 1325cm -1 It is attributed to the stretching vibration peak of the CN bond on the ligand in Hf-NTPA-2, and N is also a Lewis basic site. 3 -TPD, CO 2 -TPD and Py-IR characterization analysis show that the Lewis acidic site content of Hf-NTPA-2 is 0.732mmol / g, and the Lewis basic site content is 1.441mmol / g. The acidic site content is 0.238 mmol / g.

[0048] Next, 0.25 g of vanillin, 20 g of ethanol and 0.1 g of Hf-NTPA-2 were added to a 50 mL reactor. The reactor was sealed and the air in the reactor was replaced with nitrogen. The reactor was heated to 160 ° C at a stirring speed of 400 rpm. After 3 h of reaction, the conversion rate of vanillin was 62.1%, and the yield and selectivity of vanillin ether were 53.3% and 85.8%, respectively. This shows that the Lewis acid-base site and The acidic sites need to maintain an appropriate content and ratio to better exert a synergistic effect, thereby promoting the efficient synthesis of vanillyl alcohol ether.

[0049] Example 4

[0050] 0.25 g of vanillin, 20 g of ethanol and 0.2 g of Hf-NTPA-1 were added to a 50 mL reactor. The reactor was sealed and the air in the reactor was replaced with nitrogen. The reactor was heated to 170°C at a stirring speed of 400 rpm. After 5 h of reaction, the conversion rate of vanillin could reach 100%, and the yield and selectivity of vanillin alcohol ether were 96.8% and 96.8% respectively. Figure 7 ), which shows that appropriately increasing the reaction temperature, prolonging the reaction time and increasing the amount of catalyst can significantly enhance the Lewis acid-base sites and The synergistic effect of the acidic sites promotes the smooth conversion of vanillin and the efficient synthesis of vanillin ether. More importantly, when Hf-NTPA-1 is reused five times under the same reaction conditions, the conversion rate of vanillin can still reach 100.0%, and the yield and selectivity of vanillin ether can still reach 95.1%, which shows that Hf-NTPA-1 exhibits good catalytic stability and recyclability.

[0051] In order to verify the reaction pathway of the one-pot conversion of vanillin to vanillyl alcohol ether catalyzed by Hf-NTPA-1, Examples 5-12 (all using Hf-NTPA-1 as the catalyst) studied the types and evolution trends of the reaction substrate (vanillin), intermediates (vanillin acetal and vanillyl alcohol) and target product (vanillyl alcohol ether) in the same reaction system by changing the reaction temperature and reaction time. The specific results are shown in Table 1.

[0052] Table 1

[0053]

[0054]

[0055] It can be seen from Examples 5-12 that at different temperatures, the conversion rate of the reaction substrate, the intermediate product, and the type and yield of the target product have similar variation trends, that is, no intermediate product vanillin acetal was detected during the entire reaction process, but the intermediate product vanillin alcohol was detected, which indicates that the generation of vanillin alcohol ether uses vanillin alcohol as an intermediate product. At the same time, as the reaction time proceeds, the conversion rate of vanillin continues to increase, the yield of vanillin alcohol first increases and then decreases, and the yield of vanillin alcohol ether continues to increase, which further indicates that in the one-pot method for preparing vanillin alcohol ether, vanillin is first converted into vanillin alcohol through MPV transfer hydrogenation reaction, and vanillin alcohol is further converted into the target product through dehydration etherification reaction.

[0056] Example 13

[0057] 0.25 g of vanillin, 20 g of n-propanol and 0.2 g of Hf-NTPA-1 were added to a 50 mL reactor. The reactor was sealed and the air in the reactor was replaced with nitrogen. The reactor was heated to 170° C. at a stirring speed of 400 rpm. After reacting for 5 hours, the conversion rate of vanillin could reach 100%, and the yield and selectivity of vanillin n-propyl ether were 96.4% and 96.4%, respectively.

[0058] Embodiment 14

[0059] 0.25 g of vanillin, 20 g of isopropanol and 0.2 g of Hf-NTPA-1 were added to a 50 mL reactor. The reactor was sealed and the air in the reactor was replaced with nitrogen. The reactor was heated to 170° C. at a stirring speed of 400 rpm. After reacting for 4 hours, the conversion rate of vanillin could reach 100%, and the yield and selectivity of vanillin isopropyl ether were 98.1% and 98.1%, respectively.

[0060] Embodiment 15

[0061] 0.25 g of vanillin, 20 g of n-butanol and 0.2 g of Hf-NTPA-1 were added into a 50 mL reactor. The reactor was sealed and the air in the reactor was replaced with nitrogen. The reactor was heated to 170° C. at a stirring speed of 400 rpm. After 6 hours of reaction, the conversion rate of vanillin could reach 100%, and the yield and selectivity of vanillin n-butyl ether were 95.3% and 95.3%, respectively.

[0062] Example 16

[0063] 0.25 g of vanillin, 20 g of sec-butyl alcohol and 0.2 g of Hf-NTPA-1 were added to a 50 mL reactor. The reactor was sealed and the air in the reactor was replaced with nitrogen. The reactor was heated to 170° C. at a stirring speed of 400 rpm. After reacting for 5 hours, the conversion rate of vanillin could reach 100%, and the yield and selectivity of vanillin sec-butyl ether were 97.5% and 97.5%, respectively.

[0064] It can be seen from Examples 13-16 that Hf-NTPA-1 prepared by the "solvothermal self-assembly" strategy can not only efficiently catalyze the selective conversion of vanillin into vanillyl alcohol ether in ethanol, but also efficiently catalyze the conversion of vanillin into the corresponding vanillyl alcohol ether in different alcohols, demonstrating excellent catalytic universality.

[0065] The above is only a preferred implementation of the patent of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the patent of the present invention. These improvements and modifications should also be regarded as the scope of protection of the patent of the present invention.

Claims

1. A hafnium-based coordination polymer catalyst, characterized in that: The catalyst is a coordination polymer composed of a hafnium salt and a nitrogen-containing organic acid ligand, and the coordination polymer has Lewis acid-base sites and Acidic sites; The Lewis acid-base site is a Hf-containing organic acid group formed by a coordination bond between hafnium and nitrogen. 4+ -O 2- ; The acidic sites are -PO3H, and / or -COOH, and / or -OH on the ligand that are not involved in coordination.

2. The method for preparing the hafnium-based coordination polymer catalyst according to claim 1, characterized in that: The method comprises mixing a solution containing a hafnium salt and a nitrogen-containing organic acid ligand, adding a deprotonating agent to react, standing and aging after the reaction, and then separating, washing and drying.

3. The method for preparing the hafnium-based coordination polymer catalyst according to claim 2, characterized in that: The hafnium salt is any one of hafnium tetrachloride, hafnium dichloride and hafnium acetylacetonate; The nitrogen-containing organic acid ligand is any one of 2,5-pyridinedicarboxylic acid, cyanuric acid, citrazinic acid, iminodiacetic acid and aminotri(methylenephosphonic) acid; The deprotonating agent was triethylamine.

4. The method for preparing the hafnium-based coordination polymer catalyst according to claim 2, characterized in that: In the solution containing hafnium salt, the concentration of hafnium salt is 10-50 mmol / L; The molar ratio of the hafnium salt, the nitrogen-containing organic acid ligand and the deprotonating agent is 3:(1-4):(12-36).

5. The method for preparing the hafnium-based coordination polymer catalyst according to claim 2, characterized in that: The reaction conditions are: stirring at room temperature for 6-24 hours; the static aging conditions are: 60-100°C, 1-8 hours.

6. Use of the hafnium-based coordination polymer catalyst according to claim 1 in the one-pot method for preparing vanillin alcohol ether.

7. The use according to claim 6, characterized in that: The application is to heat and react the mixture of hafnium-based coordination polymer catalyst, low-carbon alcohol and vanillin under nitrogen atmosphere.

8. The use according to claim 6, characterized in that: The low carbon alcohol is any one of ethanol, n-propanol, isopropanol, n-butanol and sec-butanol.

9. The use according to claim 6, characterized in that: The amount of vanillin used is 1-3wt% of the amount of low-carbon alcohol used, and the amount of hafnium-based coordination polymer catalyst used is 10-100wt% of the amount of vanillin used.

10. The use according to claim 6, characterized in that: The conditions for the heating reaction are: 100-180°C, 1-10h.

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