Preparation of a modified MOFs catalyst and method for catalyzing sugars to produce propylene glycol

Abstract

The present invention proposes a method for preparing a modified MOFs catalyst and catalyzing sugars to prepare propylene glycol, which belongs to the technical field of chemical reagent preparation. The modified MOFs catalyst of the present invention is obtained by post-modifying a metal-organic framework with tungsten oxide and a transition metal. The catalyst can retain the crystal structure of MOFs, and the recovered catalyst will not have obvious structural collapse. The catalyst of the present invention can achieve complete conversion of sugars at a relatively mild temperature and ultra-low hydrogen pressure under liquid phase conditions, and highly selectively synthesizes diols with industrial value, wherein propylene glycol is the main product. The catalyst has the characteristics of being recyclable, high temperature resistant, not afraid of decomposition, and environmentally friendly.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical reagent preparation, and in particular relates to a method for preparing a modified MOFs catalyst and catalyzing sugars to prepare propylene glycol. Background Art

[0002] Given the increasing depletion of fossil resources, the development and utilization of sustainable energy to partially replace fossil resources to meet the enormous needs of today's human society has attracted great attention. Among these renewable resources, biomass is considered one of the most important sustainable resources due to its advantages such as wide availability, low pollution, and potential economic benefits. Numerous catalytic systems have been designed to realize the valorization of biomass. Diols (ethylene glycol, propylene glycol, and butanediol) are important and valuable chemicals. Among them, propylene glycol is an important raw material for the synthesis of useful chemicals such as surfactants and plasticizers, and is also an end-product used in the pharmaceutical, food, and refrigeration industries. Typical production methods for propylene glycol include petroleum product conversion and direct biomass hydrogenolysis. Biomass hydrogenolysis is relatively considered a green and environmentally friendly method because biomass contains sufficient biological raw materials, such as various sugars such as glucose, fructose, sucrose, xylose, and inulin.

[0003] Currently, most research in the field of chemical technology on the catalytic conversion of sugars into diols requires harsh conditions such as high temperature, high pressure and long reaction time, which leads to increased costs of raw materials, energy consumption and reaction equipment. In addition, it is impossible to enter the production and trading market of bulk chemicals, which limits the application areas of sugar conversion into diols. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention proposes a method for preparing a modified MOFs catalyst and catalyzing the preparation of propylene glycol from sugars.

[0005] To achieve the above objectives, the present invention provides the following technical solutions:

[0006] One of the technical solutions of the present invention:

[0007] A method for preparing a modified MOFs catalyst, using metal-organic frameworks (MOFs) as carriers, and performing tungsten oxide (WO x ) and transition metal (M) to obtain the modified MOFs catalyst (M-WO x -MOFs catalysts).

[0008] Furthermore, the loading amount of the transition metal on the metal-organic framework is 1 wt%-5 wt%, and the loading amount of the tungsten oxide on the metal-organic framework is 3 wt%-10 wt%.

[0009] Furthermore, the transition metal includes one or more of Ni, Cu, Ru, Pt and Pd.

[0010] Furthermore, the MOFs is one of MOF-74, UIO-66, MIL-101, MIL-125, HKUST-1 and ZIF-8.

[0011] Furthermore, the post-modification comprises the following steps:

[0012] The metal-organic framework, tungsten hexachloride (WCl6) and a transition metal precursor are mixed and dissolved to obtain a mixed solution, the mixed solution is transferred to a tetrafluoroethylene-lined reactor for reaction, and then washed and dried under vacuum at 60° C. overnight to obtain the modified MOFs catalyst;

[0013] Alternatively, tungsten hexachloride and a transition metal precursor are mixed and dissolved, and then impregnated onto a metal-organic framework, and subjected to a reduction reaction under a protective atmosphere to obtain the modified MOFs catalyst.

[0014] Furthermore, the mixed solution was transferred to a tetrafluoroethylene-lined reactor and reacted at 160° C. for 24 hours.

[0015] Furthermore, the reduction reaction temperature is 200° C. and the time is 4 hours.

[0016] Furthermore, the transition metal precursor includes one or more of nickel chloride hexahydrate (NiCl2·6H2O), copper chloride dihydrate (CuCl2·2H2O), ruthenium trichloride hydrate (RuCl3·xH2O), sodium hexachloroplatinate hexahydrate (Na2PtCl6·6H2O) and palladium chloride (PdCl2).

[0017] The second technical solution of the present invention:

[0018] A modified MOFs catalyst prepared by the preparation method.

[0019] The catalyst can retain the crystal structure of MOFs, and the recovered catalyst will not have obvious structural collapse.

[0020] The third technical solution of the present invention:

[0021] A method for preparing propylene glycol by catalyzing sugars, using the modified MOFs catalyst as a catalyst, mixing with sugars and a solvent, and then sealing the reaction to achieve the conversion of sugars into diols.

[0022] Furthermore, the mass ratio of the modified MOFs catalyst to the sugar is (1-20):10, and the sugar includes one or more of glucose, fructose, sucrose, xylose and inulin.

[0023] Furthermore, the sealing reaction temperature is 120-180° C. and the time is 1-6 hours.

[0024] Furthermore, the solvent includes one of water, ethanol, cyclohexane, isopropanol and γ-valerolactone.

[0025] Furthermore, the diol comprises ethylene glycol, propylene glycol and butylene glycol, wherein propylene glycol is the main product.

[0026] Furthermore, the method for preparing propylene glycol from sugars using a modified MOFs catalyst specifically comprises the following steps:

[0027] 10-200 mg of catalyst, 100 mg of sugar, and 10 mL of solvent are added to the reactor, which is then sealed and flushed with H2 multiple times to remove air from the reactor. The reactor, filled with 0.2 MPa of H2, is then heated to 120-180°C and stirred at 500 rpm for 1-6 hours. After the reaction is completed, the solid catalyst is collected by centrifugation, and the supernatant is passed through a 0.22 μm pore size filter and then analyzed by high-performance liquid chromatography to achieve the conversion of sugars to diols.

[0028] Compared with the prior art, the present invention has the following advantages and technical effects:

[0029] (1) The present invention uses sugars converted from biomass as raw materials and synthesizes M-WO by a simple hydrothermal method. x -MOFs catalyst can be used to catalyze the reaction in one kettle to produce diols with high selectivity, with propylene glycol as the main product. Under mild reaction temperature and ultra-low hydrogen pressure conditions, M-WO x The MOFs catalyst can completely convert sugars and produce high yields of propylene glycol. The catalyst's efficiency remains unchanged after multiple cycles, and the recovered catalyst retains its intact MOF structure. It boasts multiple recycling capabilities, high-temperature resistance, and environmental friendliness. The total glycol yield is 70%, with propylene glycol reaching 54%.

[0030] (2) The present invention directly synthesizes the target product in a single reaction vessel at a relatively low temperature without any intermediate steps. The target product can be obtained simply by filtering the reaction solution, thereby increasing economic benefits. The entire process has relatively high product selectivity, simple operation, a short process flow, low cost, high safety, and an environmentally friendly process. It has good prospects for industrial application and has certain strategic significance for the development of the chemical industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this application. In the accompanying drawings:

[0032] Figure 1 M-WO x - Reaction flow chart of the conversion of glucose to diols catalyzed by MOFs catalysts;

[0033] Figure 2 The Pt-WO recovered in Application Example 1 x -MOF-74(Co) and pristine Pt-WO x -XRD pattern of MOF-74(Co). DETAILED DESCRIPTION

[0034] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0035] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0036] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0037] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0038] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0039] The present invention provides a method for preparing a modified MOFs catalyst, using a metal-organic framework (MOFs) as a carrier, and performing tungsten oxide (WO x ) and transition metal (M) to obtain the modified MOFs catalyst (M-WO x -MOFs catalysts).

[0040] In a preferred embodiment of the present invention, the loading amount of the transition metal on the metal-organic framework is 1 wt%-5 wt%, and the loading amount of the tungsten oxide on the metal-organic framework is 3 wt%-10 wt%.

[0041] In a preferred embodiment of the present invention, the transition metal includes one or more of Ni, Cu, Ru, Pt and Pd.

[0042] In a preferred embodiment of the present invention, the MOFs is one of MOF-74, UIO-66, MIL-101, MIL-125, HKUST-1 and ZIF-8, which are commercially available.

[0043] In a preferred embodiment of the present invention, the post-modification comprises the following steps:

[0044] The metal-organic framework, tungsten hexachloride (WCl6) and a transition metal precursor are mixed and dissolved to obtain a mixed solution, the mixed solution is transferred to a tetrafluoroethylene-lined reactor for reaction, and then washed and dried under vacuum at 60° C. overnight to obtain the modified MOFs catalyst;

[0045] Alternatively, tungsten hexachloride and a transition metal precursor are mixed and dissolved, and then impregnated onto a metal-organic framework, and subjected to a reduction reaction under a protective atmosphere to obtain the modified MOFs catalyst.

[0046] In a preferred embodiment of the present invention, the mixed solution is transferred to a tetrafluoroethylene-lined reactor and reacted at 160° C. for 24 hours.

[0047] In a preferred embodiment of the present invention, the reduction reaction temperature is 200° C. and the time is 4 hours.

[0048] In a preferred embodiment of the present invention, the transition metal precursor includes one or more of nickel chloride hexahydrate (NiCl2·6H2O), copper chloride dihydrate (CuCl2·2H2O), ruthenium trichloride hydrate (RuCl3·xH2O), sodium hexachloroplatinate hexahydrate (Na2PtCl6·6H2O) and palladium chloride (PdCl2).

[0049] The embodiment of the present invention also provides a modified MOFs catalyst prepared by the preparation method.

[0050] The embodiment of the present invention also provides a method for catalyzing the preparation of propylene glycol from sugars, using the modified MOFs catalyst as a catalyst, mixing with sugars and a solvent, and then sealing the reaction to achieve the conversion of sugars into diols.

[0051] In a preferred embodiment of the present invention, the mass ratio of the modified MOFs catalyst to the sugar is (1-20):10, and the sugar includes one or more of glucose, fructose, sucrose, xylose and inulin.

[0052] In a preferred embodiment of the present invention, the sealing reaction is carried out at a temperature of 120-180° C. and for a time of 1-6 hours.

[0053] In a preferred embodiment of the present invention, the solvent includes one of water, ethanol, cyclohexane, isopropanol and γ-valerolactone.

[0054] In a preferred embodiment of the present invention, the diol comprises ethylene glycol, propylene glycol and butylene glycol, wherein propylene glycol is the main product.

[0055] All raw materials used in the examples of the present invention were purchased from the market.

[0056] The technical solution of the present invention is further illustrated by the following examples.

[0057] Example 1

[0058] A M-WO x -The preparation method of MOFs catalyst comprises the following steps:

[0059] 0.2 g of metal-organic framework (MOF-74(Co)), 0.03 g of tungsten hexachloride (WCl6) and 0.01 g of transition metal precursor (sodium hexachloroplatinate hexahydrate (Na2PtCl6·6H2O)) were mixed and dissolved in 25 mL of ethanol to obtain a mixed solution. The mixed solution was transferred to a tetrafluoroethylene-lined reactor and reacted at 160°C for 24 h, then washed and dried in vacuum at 60°C overnight to obtain M-WO x -MOFs catalyst (Pt-WO x -MOF-74(Co)).

[0060] Pt-WO x -In the MOF-74(Co) catalyst, the loading amount of transition metal (Pt) on the metal-organic framework is 1.4 wt%, and the loading amount of tungsten oxide on the metal-organic framework is 6.2 wt%.

[0061] Example 2

[0062] A M-WO x -The preparation method of MOFs catalyst comprises the following steps:

[0063] 0.2 g of metal-organic framework (MOF-74(Ni)), 0.03 g of tungsten hexachloride (WCl6) and 0.01 g of transition metal precursor (sodium hexachloroplatinate hexahydrate (Na2PtCl6·6H2O)) were mixed and dissolved in 25 mL of ethanol to obtain a mixed solution. The mixed solution was transferred to a tetrafluoroethylene-lined reactor and reacted at 160°C for 24 h, then washed and dried in vacuum at 60°C overnight to obtain M-WO x -MOFs catalyst (Pt-WO x -MOF-74(Ni)).

[0064] Pt-WO x -In the MOF-74(Ni) catalyst, the loading amount of transition metal (Pt) on the metal-organic framework is 1.3%, and the loading amount of tungsten oxide on the metal-organic framework is 4.9wt%.

[0065] Example 3

[0066] A M-WO x -The preparation method of MOFs catalyst comprises the following steps:

[0067] 0.2 g of metal-organic framework (MOF-74(Mg)), 0.03 g of tungsten hexachloride (WCl6) and 0.01 g of transition metal precursor (sodium hexachloroplatinate hexahydrate (Na2PtCl6·6H2O)) were mixed and dissolved in 25 mL of ethanol to obtain a mixed solution. The mixed solution was transferred to a tetrafluoroethylene-lined reactor and reacted at 160°C for 24 h, then washed and dried in vacuum at 60°C overnight to obtain M-WO x -MOFs catalyst (Pt-WO x -MOF-74(Mg)).

[0068] Pt-WO x -MOF-74(Mg) catalyst, the loading amount of transition metal (Pt) on the metal-organic framework is 1.2%, and the loading amount of tungsten oxide on the metal-organic framework is 5.6%.

[0069] Example 4

[0070] A M-WO x -The preparation method of MOFs catalyst comprises the following steps:

[0071] 0.2 g of metal-organic framework (Uio-66(Zr)), 0.01 g of tungsten hexachloride (WCl6) and 0.005 g of transition metal precursor (sodium hexachloroplatinate hexahydrate (Na2PtCl6·6H2O)) were mixed and dissolved in 25 mL of ethanol to obtain a mixed solution. The mixed solution was transferred to a tetrafluoroethylene-lined reactor and reacted at 160 °C for 24 h, then washed and dried in vacuum at 60 °C overnight to obtain M-WO x -MOFs catalyst (Pt-WO x -Uio-66(Zr)).

[0072] Pt-WO x In the Uio-66(Zr) catalyst, the loading amount of transition metal (Pt) on the metal-organic framework is 2.3%, and the loading amount of tungsten oxide on the metal-organic framework is 3.4%.

[0073] Example 5

[0074] A M-WO x -The preparation method of MOFs catalyst comprises the following steps:

[0075] 0.2 g of metal-organic framework (Uio-66(Ce)), 0.01 g of tungsten hexachloride (WCl6) and 0.005 g of transition metal precursor (sodium hexachloroplatinate hexahydrate (Na2PtCl6·6H2O)) were mixed and dissolved in 25 mL of ethanol to obtain a mixed solution. The mixed solution was transferred to a tetrafluoroethylene-lined reactor and reacted at 160 °C for 24 h, then washed and dried in vacuum at 60 °C overnight to obtain M-WO x -MOFs catalyst (Pt-WO x -Uio-66(Ce)).

[0076] Pt-WO x In the Uio-66(Ce) catalyst, the loading amount of transition metal (Pt) on the metal-organic framework is 2.1%, and the loading amount of tungsten oxide on the metal-organic framework is 3.6%.

[0077] Example 6

[0078] A M-WO x -The preparation method of MOFs catalyst comprises the following steps:

[0079] 0.2 g of metal-organic framework (MIL-101(Fe)), 0.07 g of tungsten hexachloride (WCl6) and 0.02 g of transition metal precursor (sodium hexachloroplatinate hexahydrate (Na2PtCl6·6H2O)) were mixed and dissolved in 25 mL of ethanol to obtain a mixed solution. The mixed solution was transferred to a tetrafluoroethylene-lined reactor and reacted at 160°C for 24 h, then washed and dried in vacuum at 60°C overnight to obtain M-WO x -MOFs catalyst (Pt-WO x -MIL-101(Fe)).

[0080] Pt-WO x - In the MIL-101(Fe) catalyst, the loading amount of transition metal (Pt) on the metal-organic framework is 4.8%, and the loading amount of tungsten oxide on the metal-organic framework is 9.8wt%.

[0081] Example 7

[0082] A M-WO x -The preparation method of MOFs catalyst comprises the following steps:

[0083] 0.2 g of metal-organic framework (MIL-101(Cr)), 0.07 g of tungsten hexachloride (WCl6) and 0.02 g of transition metal precursor (sodium hexachloroplatinate hexahydrate (Na2PtCl6·6H2O)) were mixed and dissolved in 25 mL of ethanol to obtain a mixed solution. The mixed solution was transferred to a tetrafluoroethylene-lined reactor and reacted at 160°C for 24 h, then washed and dried in vacuum at 60°C overnight to obtain M-WO x -MOFs catalyst (Pt-WO x -MIL-101(Cr)).

[0084] Pt-WO x - In the MIL-101(Cr) catalyst, the loading amount of transition metal (Pt) on the metal-organic framework is 5%, and the loading amount of tungsten oxide on the metal-organic framework is 10.0 wt%.

[0085] Example 8

[0086] A M-WO x -The preparation method of MOFs catalyst comprises the following steps:

[0087] 0.2 g of metal-organic framework (MIL-125(Ti)), 0.05 g of tungsten hexachloride (WCl6) and 0.007 g of transition metal precursor (sodium hexachloroplatinate hexahydrate (Na2PtCl6·6H2O)) were mixed and dissolved in 25 mL of ethanol to obtain a mixed solution. The mixed solution was transferred to a tetrafluoroethylene-lined reactor and reacted at 160°C for 24 h, then washed and dried in vacuum at 60°C overnight to obtain M-WO x -MOFs catalyst (Pt-WO x -MIL-125(Ti)).

[0088] Pt-WO x - In the MIL-125(Ti) catalyst, the loading amount of transition metal (Pt) on the metal-organic framework is 3.0 wt%, and the loading amount of tungsten oxide on the metal-organic framework is 7.2 wt%.

[0089] Example 9

[0090] A M-WO x -The preparation method of MOFs catalyst comprises the following steps:

[0091] 0.2 g of metal-organic framework (HKUST-1(Cu)), 0.05 g of tungsten hexachloride (WCl6) and 0.015 g of transition metal precursor (sodium hexachloroplatinate hexahydrate (Na2PtCl6·6H2O)) were mixed and dissolved in 25 mL of ethanol to obtain a mixed solution. The mixed solution was transferred to a tetrafluoroethylene-lined reactor and reacted at 160 °C for 24 h, then washed and dried in vacuum at 60 °C overnight to obtain M-WO x -MOFs catalyst (Pt-WO x -HKUST-1(Cu)).

[0092] Pt-WO x -HKUST-1(Cu) catalyst, the loading amount of transition metal (Pt) on the metal-organic framework is 3.2%, and the loading amount of tungsten oxide on the metal-organic framework is 8.8wt%.

[0093] Example 10

[0094] A M-WO x -The preparation method of MOFs catalyst comprises the following steps:

[0095] 0.2 g of metal-organic framework (ZIF-8(Zn)), 0.03 g of tungsten hexachloride (WCl6) and 0.01 g of transition metal precursor (sodium hexachloroplatinate hexahydrate (Na2PtCl6·6H2O)) were mixed and dissolved in 25 mL of ethanol to obtain a mixed solution. The mixed solution was transferred to a tetrafluoroethylene-lined reactor and reacted at 160 °C for 24 h, then washed and dried in vacuum at 60 °C overnight to obtain M-WO x -MOFs catalyst (Pt-WO x -ZIF-8(Zn)).

[0096] Pt-WO x -ZIF-8(Zn) catalyst, the loading amount of transition metal (Pt) on the metal-organic framework is 1.3 wt%, and the loading amount of tungsten oxide on the metal-organic framework is 6.6 wt%.

[0097] Application Example 1

[0098] 50 mg of M-WO prepared in Examples 1 to 10 was added into the reactor. x -MOFs catalyst, 100mg glucose and 10mL water, then the reactor was sealed and flushed with H2 several times to remove the air in the reactor, then the reactor filled with 0.2MPa H2 was heated to 160℃ and stirred at 500 rpm for 4 hours. After the reaction was completed, the solid catalyst was collected by centrifugation, and the supernatant was passed through a 0.22μm pore size filter and then analyzed by high performance liquid chromatography. x The reaction performance results of MOFs catalysts to generate diols are shown in Table 1. Taking glucose as an example, the reaction flow chart of catalytic conversion of sugars to diols is shown in Figure 1 .

[0099] Table 1 Different M-WO x -MOFs catalyst reaction performance results for diol production

[0100]

[0101]

[0102] Application Example 2

[0103] 50 mg of Pt-WO prepared in Example 1 was added into the reactor. x-MOF-74(Co) catalyst, 100 mg of sugar (glucose, fructose, sucrose, xylose, or inulin), and 10 mL of water were added. The reactor was then sealed and flushed with H2 several times to remove air from the reactor. The reactor, filled with 0.2 MPa of H2, was then heated to 160°C and stirred at 500 rpm for 4 hours. After the reaction, the solid catalyst was collected by centrifugation, and the supernatant was passed through a 0.22 μm pore size filter and then analyzed by high-performance liquid chromatography. The reaction performance results for the production of diols using different sugars as substrates are shown in Table 2.

[0104] Table 2 Reaction performance results of diols produced when different sugars were used as substrates

[0105] substrate Conversion rate / % Diol yield / % Propylene glycol yield / % glucose 100 70 54 fructose 100 75 56 sucrose 100 50 40 Xylose 100 45 35 Inulin 100 40 38

[0106] Application Example 3

[0107] 10-200 mg of Pt-WO prepared in Example 1 was added into the reactor. x -MOF-74(Co) catalyst, 100 mg of sugar (glucose) and 10 mL of water were added. The reactor was then sealed and flushed with H2 several times to remove the air in the reactor. The reactor, filled with 0.2 MPa of H2, was then heated to 160°C and stirred at 500 rpm for 4 hours. After the reaction, the solid catalyst was collected by centrifugation, and the supernatant was passed through a 0.22 μm pore size filter and then analyzed by high-performance liquid chromatography. The reaction performance results of glucose to diols with different catalyst dosages are shown in Table 2.

[0108] Table 3 Reaction performance results of glucose to diols at different catalyst dosages

[0109] Catalyst / mg Conversion rate / % Diol yield / % Propylene glycol yield / % 10 100 60 45 30 100 69 52 50 100 70 54 100 100 72 54 200 100 76 52

[0110] Application Example 4

[0111] 50 mg of Pt-WO prepared in Example 1 was added into the reactor. x -MOF-74(Co) catalyst, 100 mg of glucose and 10 mL of water were added, and the reactor was sealed and flushed with H2 several times to remove the air in the reactor. The reactor filled with 0.2 MPa of H2 was then heated to 120-180°C and stirred at 500 rpm for 4 hours. After the reaction was completed, the solid catalyst was collected by centrifugation, and the supernatant was passed through a 0.22 μm pore size filter and then analyzed by high-performance liquid chromatography. The reaction performance results of glucose to diols at different reaction temperatures are shown in Table 4.

[0112] Table 4 Reaction performance results of glucose to diols at different reaction temperatures

[0113] Reaction temperature / ℃ Conversion rate / % Diol yield / % Propylene glycol yield / % 120 20 20 10 140 64 34 22 160 100 70 54 180 100 74 52

[0114] Application Example 5

[0115] 50 mg of Pt-WO prepared in Example 1 was added into the reactor. x -MOF-74(Co) catalyst, 100 mg of sugar (glucose) and 10 mL of water were added. The reactor was then sealed and flushed with H2 several times to remove air from the reactor. The reactor, filled with 0.2 MPa of H2, was then heated to 160°C and stirred at 500 rpm for 1-6 hours. After the reaction, the solid catalyst was collected by centrifugation, and the supernatant was passed through a 0.22 μm pore size filter and then analyzed by high-performance liquid chromatography. The reaction performance results of glucose to diols at different reaction times are shown in Table 5.

[0116] Table 5 Reaction performance results of glucose to diols at different reaction times

[0117] Reaction time / h Conversion rate / % Diol yield / % Propylene glycol yield / % 1 65 30 19 2 76 38 26 4 100 70 54 6 100 60 50

[0118] Application Example 6

[0119] 50 mg of Pt-WO prepared in Example 1 was added into the reactor. x -MOF-74(Co) catalyst, 100 mg of sugar (glucose) and 10 mL of solvent (water, ethanol, cyclohexane, isopropanol or γ-valerolactone) were added. The reactor was then sealed and flushed with H2 several times to remove the air in the reactor. The reactor filled with 0.2 MPa of H2 was then heated to 160°C and stirred at 500 rpm for 4 hours. After the reaction was completed, the solid catalyst was collected by centrifugation, and the supernatant was passed through a 0.22 μm pore size filter and then analyzed by high performance liquid chromatography. The reaction performance results of glucose to diols in different reaction solvents are shown in Table 6.

[0120] Table 6 Reaction performance results of glucose to diols in different reaction solvents

[0121] Reaction solvent Conversion rate / % Diol yield / % Propylene glycol yield / % water 100 70 54 ethanol 100 66 48 Cyclohexane 100 69 50 Isopropyl alcohol 100 50 30 γ-Valerolactone 100 65 40

[0122] Combining the contents in Tables 1 to 6, we can see that M-WO x -MOFs can effectively convert glucose into diols, and the products are mostly concentrated in ethylene glycol; Pt-WO x -MOF-74(Co) is universal in the preparation of binary processes from various sugars, and diols will also be generated when the solvent is changed.

[0123] The Pt-WO collected by centrifugation in Application Examples 1 to 6 was x-MOF-74(Co) catalyst was subjected to catalytic cycle experiments according to the method in Example 2, using glucose as the substrate. The reaction performance results of the recovered catalyst in catalyzing glucose to diols are shown in Table 7.

[0124] Table 7 Pt-WO x -Reaction performance results of glucose to diols after multiple cycles of MOF-74(Co) catalyst

[0125] Number of cycles Conversion rate / % Diol yield / % Propylene glycol yield / % 1 100 70 54 2 100 70 54 3 100 69 53 4 100 70 55 5 100 69 53

[0126] Pt-WO after recycling in Application Example 1 x -MOF-74(Co)(Recycled-Pt-WO x -MOF-74(Co)) has the same XRD peak pattern as the original Pt-WO x -MOF-74(Co)(Fresh-Pt-WO x -MOF-74(Co)) remains consistent ( Figure 2 ).

[0127] From Table 7 and Figure 2 It can be seen that the catalytic efficiency of the catalyst of the present invention does not decrease significantly after multiple cycles of use, and the recovered catalyst retains the intact MOFs structure, and has the characteristics of being recyclable, resistant to high temperatures and not afraid of decomposition, and environmentally friendly.

[0128] Example 11-Example 20

[0129] The same as Example 1-10, except that the preparation is carried out by the impregnation method, and the specific preparation method is as follows:

[0130] Tungsten hexachloride, a transition metal precursor, ruthenium trichloride hydrate, and sodium hexachloroplatinate hexahydrate were mixed and dissolved in 10 mL of anhydrous ethanol to obtain a mixed solution. The mixed solution was impregnated onto a metal-organic framework and stirred in a water bath (70°C) until the ethanol was completely evaporated. The solid powder was then reduced in a tubular furnace under a hydrogen atmosphere for 4 hours at a reduction temperature of 200°C and a heating rate of 5°C / min to prepare a catalyst.

[0131] The types and amounts of the raw materials are exactly the same as those in Examples 1-10.

[0132] The catalyst prepared in Example 11 is recorded as Pt-WO x -MOF-74(Co)-1.

[0133] The catalyst prepared in Example 12 is recorded as Pt-WO x -MOF-74(Ni)-1.

[0134] The catalyst prepared in Example 13 is recorded as Pt-WO x -MOF-74(Mg)-1.

[0135] The catalyst prepared in Example 14 is recorded as Pt-WO x -Uio-66(Zr)-1.

[0136] The catalyst prepared in Example 15 is recorded as Pt-WO x -Uio-66(Ce)-1.

[0137] The catalyst prepared in Example 16 is recorded as Pt-WO x -MIL-101(Fe)-1.

[0138] The catalyst prepared in Example 17 is recorded as Pt-WO x -MIL-101(Cr)-1.

[0139] The catalyst prepared in Example 18 is recorded as Pt-WO x -MIL-125(Ti)-1.

[0140] The catalyst prepared in Example 19 is recorded as Pt-WO x -HKUST-1(Cu)-1.

[0141] The catalyst prepared in Example 20 is recorded as Pt-WO x -ZIF-8(Zn)-1.

[0142] Application Example 7

[0143] 50 mg of the catalyst prepared in Examples 11 to 20, 100 mg of glucose and 10 mL of water were added to the reactor respectively. The reactor was then sealed and flushed with H2 several times to remove the air in the reactor. The reactor filled with 0.2 MPaH2 was then heated to 160°C and stirred at 500 rpm for 4 hours. After the reaction was completed, the solid catalyst was collected by centrifugation, and the supernatant was passed through a filter with a pore size of 0.22 μm and then analyzed by high performance liquid chromatography. The reaction performance results of different catalysts for producing diols are shown in Table 8.

[0144] Table 8 Reaction performance results of different catalysts to generate diols

[0145]

[0146]

[0147] The data in Tables 1 and 8 demonstrate that the present invention utilizes the M-WOx-MOFs catalyst synthesized by a simple hydrothermal method, enabling a single-pot reaction and highly selective production of diols. Under relatively mild reaction temperatures and ultra-low hydrogen pressures, the M-WOx-MOFs catalyst can completely convert sugars and produce high yields of propylene glycol. Compared to the catalyst prepared using the in-situ hydrothermal method in the present embodiment, the catalyst prepared using the impregnation method exhibits superior performance because the hydrothermal method avoids metal particle agglomeration.

[0148] The above are merely preferred embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for preparing a modified MOFs catalyst, characterized in that: Using a metal-organic framework as a carrier, post-modifying it with tungsten oxide and transition metal to obtain the modified MOFs catalyst; The loading amount of the transition metal on the metal-organic framework is 1 wt%-5 wt%, and the loading amount of the tungsten oxide on the metal-organic framework is 3 wt%-10 wt%; The transition metal includes one or more of Ni, Cu, Ru, Pt and Pd; The post-modification comprises the following steps: The metal-organic framework, tungsten hexachloride and a transition metal precursor are mixed and dissolved to obtain a mixed solution, the mixed solution is transferred to a tetrafluoroethylene-lined reactor for reaction, and then washed and vacuum-dried to obtain the modified MOFs catalyst; Alternatively, tungsten hexachloride and a transition metal precursor are mixed and dissolved, and then impregnated onto a metal-organic framework, and subjected to a reduction reaction under a protective atmosphere to obtain the modified MOFs catalyst; The mixed solution was transferred to a tetrafluoroethylene-lined reactor and reacted at 160° C. for 24 h; The reduction reaction temperature is 200° C. and the time is 4 hours.

2. A modified MOFs catalyst prepared by the preparation method according to claim 1.

3. A method for catalyzing the preparation of propylene glycol from sugars, characterized in that: The modified MOFs catalyst according to claim 2 is used as a catalyst, mixed with sugars and a solvent, and then sealed to react to achieve the conversion of sugars into diols.

4. The method for preparing propylene glycol by catalyzing sugars according to claim 3, characterized in that: The mass ratio of the modified MOFs catalyst to the sugar is (1-20):10, and the sugar includes one or more of glucose, fructose, sucrose, xylose and inulin.

5. The method for preparing propylene glycol by catalyzing sugars according to claim 3, characterized in that: The sealing reaction temperature is 120-180° C. and the time is 1-6 hours.

6. The method for preparing propylene glycol by catalyzing sugars according to claim 3, characterized in that: The solvent includes one of water, ethanol, cyclohexane, isopropanol and γ-valerolactone.

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