Method for preparing functionalized triazine covalent organic framework material and application of functionalized triazine covalent organic framework material in preparation of low-carbon alcohol by catalyzing cellulose

Abstract

The invention relates to the field of new material development and catalysis, and provides a method for preparing a functionalized triazine covalent organic framework material and application of the functionalized triazine covalent organic framework material in catalyzing cellulose to prepare low-carbon alcohol, and the method comprises the following steps: taking a monomer with at least two nitrile bonds as a raw material, taking tungsten salt as a catalyst, carrying out a reaction by adopting an ionothermal method, and after the reaction is completed, adding water to continue the reaction to obtain the functionalized triazine covalent organic framework material. And collecting a product to obtain the triazine covalent organic framework material loaded with the tungsten-containing compound, namely the functionalized triazine covalent organic framework material. The WOx / CTFs are prepared in one step, the steps are simple, the reaction conditions are relatively mild, the application requirements can be met, and W is tightly loaded on the CTFs. The functionalized covalent triazine framework material prepared by the invention can efficiently catalyze cellulose to prepare low-carbon alcohol.

Description

Technical Field

[0001] The invention belongs to the field of new material development and catalysis, and specifically relates to a method for preparing a functionalized triazine covalent organic framework material and an application of the method in catalyzing cellulose to prepare low-carbon alcohols. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Cellulose is the most abundant biomass resource in nature. It is inexpensive and renewable. It can be used to produce high-value bio-based chemicals or fuels such as low-carbon alcohols through biorefining technology, which is not only conducive to reducing the consumption of petrochemical resources, but also can increase the high-value-added use of cellulose and achieve the sustainable development of low-carbon alcohols. The one-step liquid-phase catalytic preparation of low-carbon alcohols from cellulose 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). It has excellent catalytic activity and selectivity, and can achieve good cellulose conversion rate and low-carbon alcohol yield.

[0004] Covalent organic frameworks (COFs) are a type of crystalline porous polymer materials formed by organic molecules connected by covalent bonds. This type of material has excellent properties and strong covalent forces between the frameworks. At the same time, since this type of material is composed of light elements such as C, N, H, and O, it has a low density and is widely used in adsorption, catalysis, separation and other fields. Covalent triazine frameworks (CTFs) are a type of COFs connected by triazine rings. In recent years, CTFs have been widely used because they do not contain metal elements, have high temperature stability and chemical stability, high porosity and pore structure that can be designed. They can be used for gas storage or separation, adsorption, catalysis, electronic materials, etc. CTFs are often prepared from nitrile-containing monomers using ion thermal method or trifluoromethanesulfonic acid catalysis. Zinc chloride and ferric chloride are often used as catalysts in the preparation of CTFs by ion thermal method. After the reaction, hydrochloric acid soaking is required to remove residual metal chlorides. There are problems such as long preparation time, equipment corrosion, and pollution caused by acidic wastewater. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a method for preparing a functionalized triazine covalent organic framework material and catalyzing cellulose to prepare low-carbon alcohols. The present invention integrates the synthesis of covalent triazine framework materials and functionalized covalent triazine framework catalysts, does not require hydrochloric acid to remove metal chlorides, has simple steps and is environmentally friendly.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

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

[0008] 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.

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

[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 having at least two nitrile bonds to tungsten is 1:0.5 to 1:2.

[0012] In some embodiments, the reaction conditions of the ion thermal method are: reacting at 225-300° C. for 8-48 hours. Preferably, reacting at 245-275° C. for 12-24 hours.

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

[0014] In some embodiments, the reaction is carried out in a pressure-resistant glass bottle or a stainless steel reactor lined with tetrafluoroethylene. After the monomer and tungsten chloride are mixed, they are transferred to the reaction container, filled with inert gas and sealed under an inert gas atmosphere, and then heated to react.

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

[0016] More specifically, the method includes: 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, adding deionized water and stirring overnight, then filtering and vacuum drying to obtain a triazine covalent organic framework material loaded with a tungsten-containing compound, i.e., a functionalized triazine covalent organic framework material. The functionalized triazine covalent organic framework material is used to prepare low-carbon alcohols from cellulose in a one-step liquid phase catalysis in a reactor.

[0017] The second aspect of the present invention provides a functionalized triazine covalent organic framework material prepared by the above method.

[0018] The third aspect of the present invention provides a catalyst, wherein ruthenium is loaded on the above-mentioned functionalized triazine covalent organic framework material, or the above-mentioned functionalized triazine covalent organic framework material is mixed with Ru / C.

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

[0020] More specifically, WO x / CTFs were placed in a mixed solution of ethylene glycol and water, ruthenium chloride hydrate was added, and ruthenium metal was loaded and reduced under a hydrothermal environment to obtain a functionalized triazine covalent organic framework material (Ru-WO x / CTFs).

[0021] The fourth aspect of the present invention provides the use of the above-mentioned functionalized triazine covalent organic framework material and catalyst in catalyzing the preparation of low-carbon alcohols from cellulose.

[0022] More specifically, the method comprises: mixing cellulose, Ru-WOx / CTFs or WO x / CTFs and Ru / C are placed in a high-temperature and high-pressure reactor in proportion, an appropriate amount of water is added, and the temperature is controlled under a hydrogen atmosphere to react and prepare low-carbon alcohols.

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

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

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

[0026] Beneficial Effects of the Invention

[0027] (1) The present invention uses tungsten chloride as a catalyst in the preparation process of functionalized triazine covalent organic framework materials, and then adds water to make the tungsten chloride react with water to be converted into tungsten oxide in situ. After the reaction is completed, it is not necessary to soak it in hydrochloric acid, nor is it necessary to use toxic organic solvents such as tetrahydrofuran, dichloromethane, N,N-dimethylformamide for cleaning. The preparation method is simple, green, and pollution-free. The tungsten oxide is tightly loaded on the carrier and can be further loaded with Ru or cooperated with Ru / C to catalyze cellulose to prepare low-carbon alcohols, thereby expanding the application range of covalent triazine framework materials.

[0028] (2) The preparation process of the present invention is simple. For example, when a functionalized covalent triazine framework material is used to catalyze cellulose to prepare low-carbon alcohols, the usual method is to use zinc chloride or the like as a catalyst to prepare a triazine covalent organic framework material, then use hydrochloric acid to remove metal chlorides such as zinc chloride, and then use an organic solvent to wash and remove the remaining unreacted monomers to obtain CTFs, and then load WOx and Ru. In comparison, the present invention prepares WOx / CTFs in one step, has simple steps, and relatively mild reaction conditions, which can meet application requirements, and W is tightly loaded on CTFs.

[0029] (3) The method of the present invention is highly practical and easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention, and the exemplary embodiments of the present invention and their description are used to explain the present invention and do not constitute improper limitations on the present invention.

[0031] Figure 1 : is a structural diagram of a triazine covalent organic framework material in an embodiment of the present invention, wherein the monomers used are terephthalonitrile, isophthalonitrile, and methylterephthalonitrile;

[0032] Figure 2 WO prepared in the embodiment of the present invention x / XRD patterns of CTFs;

[0033] Figure 3 WO prepared in the embodiment of the present invention x Infrared spectrum of / CTFs. DETAILED DESCRIPTION

[0034] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0035] The present invention will be further described in detail below in conjunction with specific embodiments. It should be noted that the specific embodiments are intended to explain the present invention rather than to limit it.

[0036] Example 1

[0037] Ru-WO x Preparation of CTFs and catalysis of cellulose to produce low-carbon alcohols

[0038] Step 1WO x Preparation of CTFs-1

[0039] Weigh terephthalonitrile (1 g) and tungsten hexachloride (1 g) in a mortar, grind for 5 min to mix evenly, transfer to a covered porcelain boat, then put the covered porcelain boat into a tube furnace, pass nitrogen, the nitrogen flow rate is 0.25 L / min, the heating rate is 5 ° C / min, keep at 275 ° C for 24 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 for more than 10 h, 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 1 g of hydrated ruthenium chloride (Ru content 36%) in 100 mL of deionized water to obtain a ruthenium chloride aqueous solution. x / CTFs-1 0.3g, add 40mL ethylene glycol, stir and disperse evenly, add 4mL prepared ruthenium chloride aqueous solution, and then add 26mL deionized water. After fully stirring, ultrasonicate for 30min, then put the mixed liquid into a stainless steel reactor with a tetrafluoroethylene liner, put it into a drying oven, keep it at 210℃ for 4h, cool it to room temperature, filter it, and vacuum dry it 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 cellulose was put into a Parr reactor, 50mL deionized water was added, hydrogen was filled and circulated for 5 times to remove the air in the reactor, and 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, it 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 preparation 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 min to mix evenly, transfer to a vial, seal with a capping device under nitrogen atmosphere, keep at 245 ° C in a drying oven for 12 h, 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 and Ru / C catalyze the preparation of low-carbon alcohols from cellulose

[0049] 150mg WO x / CTFs-2, 100mg Ru / C, 0.5g cellulose were put into a Parr reactor, 50mL water was added, hydrogen was filled and circulated for 5 times to remove the air in the reactor, and 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 filtering with a 0.45um filter membrane, the product was tested by 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), put them in a mortar, grind for 5 minutes to mix evenly, transfer them to a syringe bottle, seal them with a capping machine under a nitrogen atmosphere, keep them at 245 ° C in a drying oven for 12 h, keep them at 245 ° C for 12 h, cool them naturally to room temperature, take them 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 them 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 peak near 2226 is the characteristic peak of the nitrile bond, and the peaks near 1510 and 1355 are the characteristic peaks of 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 description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

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.

2. The method for preparing a functionalized triazine covalent organic framework material according to claim 1, characterized in that: The monomer having at least two nitrile bonds is selected from at least one of terephthalonitrile, isophthalonitrile and methylterephthalonitrile.

3. The method for preparing a functionalized triazine covalent organic framework material according to claim 1, characterized in that: The tungsten salt is selected from at least one of tungsten hexachloride, tungsten pentachloride and tungsten tetrachloride.

4. The method for preparing a functionalized triazine covalent organic framework material according to claim 1, characterized in that: The mass ratio of the monomer having at least two nitrile bonds to tungsten is 1:0.5 to 1:

2.

5. The method for preparing a functionalized triazine covalent organic framework material according to claim 1, characterized in that: The reaction conditions of the ion thermal method are: reacting at 225-300° C. for 8-48 hours; Alternatively, react at 245-275°C for 12-24h.

6. The method for preparing a functionalized triazine covalent organic framework material according to claim 1, characterized in that: The inert atmosphere is selected from at least one of nitrogen, argon and helium.

7. A functionalized triazine covalent organic framework material prepared by the method according to any one of claims 1 to 6.

8. A catalyst, characterized in that Ruthenium is loaded on the functionalized triazine covalent organic framework material of claim 7, or the functionalized triazine covalent organic framework material of claim 7 is mixed with Ru / C.

9. The catalyst according to claim 8, characterized in that The mass ratio of the triazine covalent organic framework material loaded with the tungsten-containing compound to the ruthenium salt is 0.3-0.5:

1.

10. Use of the functionalized triazine covalent organic framework material according to claim 7 and the catalyst according to claim 8 or 9 in catalyzing the preparation of low-carbon alcohols from cellulose.

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