A method for preparing a functionalized triazine covalent organic framework material and its application in catalyzing cellulose to prepare low-carbon alcohol

Abstract

The application provides a method for preparing a functionalized triazine covalent organic framework material and application of the functionalized triazine covalent organic framework material in catalysis of cellulose to prepare low-carbon alcohols, and belongs to the fields of new material development and catalysis, and comprises the following steps: using a monomer with at least two nitrile bonds as raw material, using a tungsten salt as a catalyst, and adopting an ionothermal method to perform reaction; after the reaction is completed, water is added to continue the reaction; and then the product is collected to obtain a triazine covalent organic framework material loaded with a tungsten compound, namely the functionalized triazine covalent organic framework material. The WOx / CTFs is prepared in one step, the steps are simple, the reaction condition is relatively mild, the application needs can be met, and the W is tightly loaded on the CTFs. The functionalized covalent triazine framework material prepared in the application can efficiently catalyze the cellulose to prepare low-carbon alcohols.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of new material development and catalysis, and particularly relates to a method for preparing functionalized triazine covalent organic framework material and application thereof in catalyzing cellulose to prepare low-carbon alcohol. BACKGROUND

[0002] The information disclosed in this Background section is only for the purpose of increasing the understanding of the general background of the application and does not necessarily constitute an admission that the information forms part of the prior art already known to a person of ordinary skill in the art.

[0003] Cellulose is the most abundant biomass resource in nature, is low in price and renewable, and can be used to prepare high-value low-carbon alcohol and other bio-based chemicals or fuels through biorefining technology, which is not only conducive to reducing the consumption of petrochemical resources, but also can improve the high-value use of cellulose and realize the sustainable development of low-carbon alcohol. The one-step liquid-phase catalytic cellulose preparation of low-carbon alcohol usually uses multifunctional catalysts loaded with transition metals such as nickel (Ni) and ruthenium (Ru) or / and compounds such as tungsten (W) and molybdenum (Mo), which has excellent catalytic activity and selectivity, and can achieve good cellulose conversion rate and low-carbon alcohol yield.

[0004] Covalent organic framework material (COFs) is a kind of crystalline porous polymer material formed by covalent bond connection of organic molecules. This kind of material has very excellent characteristics, and has very strong covalent force between the frameworks. At the same time, since this kind of material is composed of light elements such as C, N, H and O, it has low density and is widely used in the fields of adsorption, catalysis, separation, etc. Covalent triazine framework (CTF) is a kind of COFs connected by triazine rings, which has been widely used in recent years due to its metal-free, high-temperature stability and chemical stability, high porosity and designable pore structure, and can be used for gas storage or separation, adsorption, catalysis, electronic materials, etc. CTFs are usually prepared from monomers containing nitrile groups by ionothermal method or triflic acid catalysis method. The ionothermal method for preparing CTFs usually uses zinc chloride and iron chloride as catalysts, and needs to be soaked in hydrochloric acid after reaction to remove residual metal chlorides, which has problems such as long preparation time, equipment corrosion and pollution caused by acid wastewater. SUMMARY

[0005] In order to solve the above problems, the present application provides a method for preparing functionalized triazine covalent organic framework material and catalyzing cellulose to prepare low-carbon alcohol. The present application integrates the synthesis of covalent triazine framework material and functionalized covalent triazine framework catalyst, and does not need to remove metal chlorides with hydrochloric acid, which is simple and environmentally friendly.

[0006] To achieve the above object, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a method for preparing a functionalized triazine covalent organic framework material, comprising:

[0008] The method uses a monomer with at least two nitrile bonds as raw material, a tungsten salt as catalyst, and ionothermal method for reaction. After the reaction is completed, water is added for continuous reaction. The product is collected to obtain a triazine covalent organic framework material loaded with tungsten compound, i.e. a functionalized triazine covalent organic framework material.

[0009] In some embodiments, the monomer with at least two nitrile bonds is selected from at least one of terephthalonitrile, isophthalonitrile, and methyl terephthalonitrile.

[0010] In some embodiments, the tungsten salt is selected from at least one of tungsten hexachloride, tungsten pentachloride, and tungsten tetrachloride.

[0011] In some embodiments, the mass ratio of the monomer with at least two nitrile bonds to tungsten is 1:0.5-1:2.

[0012] In some embodiments, the reaction condition of the ionothermal method is 225-300℃ for 8-48h. Preferably, the reaction is carried out at 245-275℃ for 12-24h.

[0013] In some embodiments, the reaction is carried out in a tube furnace, the inert gas flow rate of the tube furnace is 0.2-0.5L / min, and the temperature rising rate is 5℃ / min.

[0014] In some embodiments, the reaction is carried out in a pressure-resistant glass bottle or a stainless steel reaction kettle with a tetrafluoroethylene lining. After the monomer and tungsten chloride are mixed and transferred to the reaction container, the container is sealed after being filled with inert gas and then heated for reaction.

[0015] In some embodiments, the inert atmosphere is selected from at least one of nitrogen, argon, and helium.

[0016] More specifically, the method comprises: uniformly mixing and grinding the nitrile monomer and tungsten chloride in a mortar according to a certain mass ratio, then transferring to an inert gas atmosphere for heating, cooling to room temperature, placing the sample in a beaker, stirring with deionized water overnight, then filtering and vacuum drying to obtain a triazine covalent organic framework material loaded with tungsten compound, i.e. a functionalized triazine covalent organic framework material. The functionalized triazine covalent organic framework material is applied to one-step liquid-phase catalytic preparation of low-carbon alcohol from cellulose in a reaction kettle.

[0017] In a second aspect, the present application provides a functionalized triazine covalent organic framework material prepared by the above method.

[0018] In a third aspect of the present application, a catalyst is provided, in which ruthenium is loaded on the functionalized triazine covalent organic framework material described above, or the functionalized triazine covalent organic framework material described above is mixed with Ru / C.

[0019] In some embodiments, the mass ratio of the triazine covalent organic framework material loaded with tungsten-containing compounds to the ruthenium salt is 0.3-0.5:1.

[0020] More specifically, WO x The functionalized triazine covalent organic framework material (Ru-WO x / CTFs) is obtained by placing the WO

[0021] In a fourth aspect of the present application, the functionalized triazine covalent organic framework material and the catalyst described above are used for catalyzing the preparation of low-carbon alcohols from cellulose.

[0022] More specifically, the method comprises: placing cellulose, Ru-WOx / CTFs or WO x / CTFs and Ru / C in a high-temperature and high-pressure reaction kettle according to a ratio, adding an appropriate amount of water, and reacting under a hydrogen atmosphere to prepare low-carbon alcohols by controlling the temperature.

[0023] In some embodiments, the concentration of the cellulose is 10-100 g / L.

[0024] In some embodiments, the amount of the functionalized CTFs is 10%-40% of the cellulose.

[0025] In some embodiments, the catalytic temperature is 230-250℃, and the catalytic time is 1-3 h; preferably, the catalytic temperature is 245℃, and the catalytic time is 2 h.

[0026] Advantages of the present application

[0027] (1) In the preparation of the functionalized triazine covalent organic framework material, tungsten chloride is used as a catalyst, and then water is added to react the tungsten chloride with water in situ to convert the tungsten chloride into tungsten oxide. After the reaction, no hydrochloric acid is needed for soaking, and no toxic organic solvents such as tetrahydrofuran, dichloromethane, and N,N-dimethylformamide are needed for cleaning. The preparation method is simple, green, and pollution-free. The tungsten oxide is closely loaded on the carrier, and can be further loaded with Ru or cooperated with Ru / C for catalyzing the preparation of low-carbon alcohols from cellulose, thereby expanding the application range of the covalent triazine framework material.

[0028] (2) The preparation process of the present application is simple, such as using functional covalent triazine framework material to catalyze cellulose to prepare low-carbon alcohol, and the general method is to use zinc chloride and the like as a catalyst to prepare triazine covalent organic framework material, then soak in hydrochloric acid to remove metal chlorides such as zinc chloride, then use an organic solvent to clean to remove residual unreacted monomers to obtain CTFs, and then load WOx and Ru, compared with the above, the present application prepares WOx / CTFs in one step, the steps are simple, and the reaction conditions are relatively mild, which can meet the application needs, and W is tightly loaded on CTFs.

[0029] (3) The method of the present application has strong practicability and is easy to popularize. BRIEF DESCRIPTION OF DRAWINGS

[0030] The drawings constituting a part of the specification of the present application are used to provide further understanding of the present application, the exemplary embodiments of the present application and the description thereof are used to explain the present application, and do not constitute improper limitation on the present application.

[0031] Figure 1 It is a structure diagram of triazine covalent organic framework material in the embodiment of the present application, and the monomers used are p-phenylenedinitrile, m-phenylenedinitrile and methyl p-phenylenedinitrile, respectively;

[0032] Figure 2 It is an XRD spectrum of WO x / CTFs prepared in the embodiment of the present application;

[0033] Figure 3 It is an infrared spectrum of WO x / CTFs prepared in the embodiment of the present application. DETAILED DESCRIPTION

[0034] It should be pointed out that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in the present application have the same meaning as generally understood by those skilled in the art to which the present application belongs.

[0035] The present application will be further described in detail below in combination with specific embodiments, and it should be pointed out that the specific embodiments are an explanation of the present application rather than a limitation.

[0036] Example 1

[0037] Preparation of Ru-WO x / CTFs and catalysis of cellulose to prepare low-carbon alcohol

[0038] Preparation of WO x / CTFs-1

[0039] Weigh terephthalonitrile (1 g) and tungsten hexachloride (1 g) into a mortar, grind for 5 minutes to mix evenly, and then transfer to a covered porcelain boat. Then, place the covered porcelain boat into a tube furnace, pass nitrogen at a nitrogen flow rate of 0.25 L / min, and heat at a rate of 5°C / min. Maintain at 275°C for 24 hours. After cooling naturally to room temperature, take out the product, transfer it to a beaker, add about 100 mL of deionized water, stir for more than 10 hours, vacuum filter, and then vacuum dry at 80°C overnight to obtain the product WO x / CTFs-1.

[0040] Step 2Ru-WO x Preparation of CTFs

[0041] Dissolve 1g of hydrated ruthenium chloride (Ru content 36%) in 100mL of deionized water to obtain a ruthenium chloride aqueous solution. x 0.3 g of / CTFs-1 was added to 40 mL of ethylene glycol and stirred to disperse evenly. 4 mL of the prepared ruthenium chloride aqueous solution was added, followed by 26 mL of deionized water. After thorough stirring, the mixture was ultrasonicated for 30 minutes. The mixture was then placed in a stainless steel reactor lined with tetrafluoroethylene and placed in a drying oven at 210°C for 4 hours. After cooling to room temperature, it was filtered and vacuum dried overnight to obtain Ru-WO. x / CTFs.

[0042] Step 3Ru-WO x Preparation of low-carbon alcohols from cellulose catalyzed by CTFs

[0043] 125 mg Ru-WO x / CTFs, 0.5g of cellulose was placed in a Parr reactor, 50mL of deionized water was added, and hydrogen was circulated for 5 times to remove the air in the reactor. Then, hydrogen was filled to 5Mpa, and the reaction was carried out at 245°C and a rotation speed of 500rpm / min for 2h. After the reaction was completed and cooled to room temperature, the product was filtered with a 0.45um filter membrane and tested by high performance liquid chromatography. The yield of ethylene glycol was 47.7%, the yield of 1,2-butanediol was 6.2%, and the yield of 1,2-hexanediol was 0.7%.

[0044] Example 2

[0045] WO x Preparation of / CTFs-2 and its catalytic effect on the production of low-carbon alcohols from cellulose

[0046] Step 1WO x Preparation of CTFs-2

[0047] Weigh isophthalonitrile (2 g) and tungsten pentachloride (2 g) in a mortar, grind for 5 minutes to mix evenly, transfer to a vial, seal with a capper under nitrogen atmosphere, keep at 245 ° C in a drying oven for 12 hours, cool naturally to room temperature, take out, transfer the product in the vial to a beaker, add about 100 mL of deionized water, stir overnight, vacuum filter, and then vacuum dry at 80 ° C overnight to obtain the product WO x / CTFs-2.

[0048] Step 2WO x / CTFs-2 synergistically with Ru / C to prepare low-carbon alcohols from cellulose

[0049] 150mg WO x / CTFs-2, 100 mg Ru / C, and 0.5 g cellulose were placed in a Parr reactor, 50 mL of water was added, and hydrogen was circulated for 5 times to remove air from the reactor. Then, hydrogen was filled to 5 MPa and reacted at 245°C and 500 rpm / min for 2 h. After filtration through a 0.45 μm filter membrane and testing using high-performance liquid chromatography, the yield of ethylene glycol was 39.5%, and the yield of 1,2-butanediol was 1.0%.

[0050] Example 3

[0051] Weigh methyl terephthalonitrile (1 g) and tungsten pentachloride (1.1 g) in a mortar, grind for 5 minutes to mix evenly, transfer to a penicillin bottle, seal with a capper under nitrogen atmosphere, keep at 245 ° C in a drying oven for 12 h, keep at 245 ° C for 12 h, cool naturally to room temperature, take out, transfer the product in the porcelain boat to a beaker, add about 100 mL of deionized water, stir overnight, vacuum filter, and then vacuum dry at 80 ° C overnight to obtain the product WOx / CTFs-3.

[0052] The structure diagram of the triazine covalent organic framework material in Examples 1-3 is as follows Figure 1 As shown, the XRD patterns of Examples 1 and 2 are as follows Figure 2 As shown, the infrared spectra of Examples 1-3 are as follows Figure 3 As shown, the characteristic peak near 2226 is the nitrile bond, and the characteristic peaks near 1510 and 1355 are the triazine ring. It can be seen from the infrared spectrum that after the reaction, the characteristic peak corresponding to the nitrile bond is weak (especially when terephthalonitrile and isophthalonitrile are used as monomers), and the characteristic peak corresponding to the triazine ring proves the synthesis of the triazine covalent organic framework material.

[0053] The above merely provides the preferred embodiments of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the principles and technical scope of the present application shall fall into the scope of the present application.

Claims

1. A method for preparing a functionalized triazine covalent organic framework material, characterized in that: include: A monomer with at least two nitrile bonds is used as a raw material, a tungsten salt is used as a catalyst, and an ion thermal method is used to react. After the reaction is completed, water is added to continue the reaction, and the product is collected to obtain a triazine covalent organic framework material loaded with a tungsten-containing compound, namely: a functionalized triazine covalent organic framework material; The monomer having at least two nitrile bonds is selected from at least one of terephthalonitrile, isophthalonitrile, and methylterephthalonitrile; The tungsten salt is selected from at least one of tungsten hexachloride, tungsten pentachloride and tungsten tetrachloride; The mass ratio of the monomer having at least two nitrile bonds to tungsten is 1:0.5 to 1:

2.

2. The method for preparing a functionalized triazine covalent organic framework material according to claim 1, wherein: The reaction conditions of the ion thermal method are: reaction at 225-300° C. for 8-48 hours.

3. The method for preparing a functionalized triazine covalent organic framework material according to claim 1, wherein: The reaction conditions of the ion thermal method are: reaction at 245-275° C. for 12-24 hours.

4. A functionalized triazine covalent organic framework material prepared by the method according to any one of claims 1 to 3.

5. A catalyst, characterized in that Ruthenium is loaded on the functionalized triazine covalent organic framework material according to claim 4, or the functionalized triazine covalent organic framework material according to claim 4 is mixed with Ru / C.

6. Use of the functionalized triazine covalent organic framework material according to claim 4 or the catalyst according to claim 5 in catalyzing the production of lower alcohols from cellulose.

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