CN106279077A - A kind of method that composite mixed phosphotungstate catalyzes and synthesizes 5 Hydroxymethylfurfural - Google Patents

Abstract

The invention relates to a method for catalytically synthesizing 5-hydroxymethylfurfural with compound-doped phosphotungstate, using compound-doped phosphotungstate as a catalyst, and dehydrating and synthesizing it from fructose in N,N-dimethylformamide solvent 5‑Hydroxymethylfurfural. The structural formula of the composite doped phosphotungstate used in the present invention is: , wherein, R=-C ₁₆ H ₃₃ or -C ₁₈ H ₃₇ , x=0.25~1.0, y=0.25~1.0. The invention has the advantages that the complex doped phosphotungstate involved has high catalytic activity and good selectivity, thereby realizing efficient synthesis of 5-hydroxymethylfurfural, and the catalyst preparation process is simple, easy to separate, and reusable.

Description

A kind of compound doped phosphotungstate catalyzed method for synthesizing 5-hydroxymethylfurfural

technical field

The invention relates to a method for synthesizing 5-hydroxymethylfurfural, in particular to a method for catalytically synthesizing 5-hydroxymethylfurfural with composite doped phosphotungstate.

Background technique

At present, the energy used in the world mainly comes from non-renewable resources such as oil, coal and natural gas. With the decrease of fossil resources, the development of sustainable resources has become the focus of the world. Biomass is a sustainable resource that is abundant, cheap, biodegradable, and constantly regenerated. As a new type of biomass-based platform compound, 5-hydroxymethylfurfural and its disubstituted derivatives can be used as one of the excellent substitutes for petroleum fuels. Its monomers can be synthesized with optical activity and biodegradability. It is a special polymer material, and because of its highly active furan ring, aromatic alcohol, and aromatic aldehyde structure, it can be used to prepare insecticides, pesticides, fungicides, perfumes, fragrances, etc.

The process route of preparing 5-hydroxymethylfurfural by dehydration of fructose is considered to be the most promising, and one of its key technologies lies in the development of high-efficiency catalysts. Although liquid acid catalysts such as sulfuric acid have high catalytic activity for the dehydration of fructose to prepare 5-hydroxymethylfurfural, there are many by-products in the reaction, high energy consumption for product separation, severe corrosion of equipment by sulfuric acid, and a large amount of acid-containing wastewater , causing serious environmental pollution. Therefore, in recent years, the development of catalysts for the preparation of 5-hydroxymethylfurfural from fructose dehydration at home and abroad has mainly focused on solid acids. Heteropolyacids and their salts have the advantages of strong acidity, high surface acid center density and easy preparation, and are a class of high-efficiency solid acid catalysts that have attracted widespread attention. Qu Jingping used heteropolyacids or heteropolyacids to catalyze fructose to prepare 5-hydroxymethylfurfural, but the yield was less than 72% (Qu Jingping, CN 101289435A); Qu Yongshui et al. studied different phosphotungstates on Fructose hydrolysis effect, and found that with CePW ₁₂ O ₄₀ as catalyst, fructose was reacted at 160°C for 8 hours, and the molar yield of 5-hydroxymethylfurfural exceeded 90% (Qu Yongshui et al., Journal of Beijing University of Chemical Technology, 2012 , 39(4):12-16); Xu Jie et al. used silica-based hydrophobic nano-solid acid materials to catalyze the dehydration of fructose to prepare 5-hydroxymethylfurfural, with a maximum yield of 85% (Xu Jie et al., CN 103788033A) .

The existing technical solutions still have defects such as high reaction temperature, long reaction time, low product yield, and poor reusability of the catalyst. Therefore, it is still an urgent technical problem for those skilled in the art to develop a solid acid catalyst that is efficient, stable, easy to separate and has good reusability.

Contents of the invention

The object of the present invention is to provide a method for synthesizing 5-hydroxymethylfurfural with high efficiency, low energy consumption and environmental friendliness.

The invention provides a method for catalytically synthesizing 5-hydroxymethylfurfural with composite doped phosphotungstate: using composite doped phosphotungstate as a catalyst, dehydrating fructose in N,N-dimethylformamide solvent Synthesize 5-hydroxymethylfurfural, the structural formula of the composite doped phosphotungstate is:

Wherein, R=-C ₁₆ H ₃₃ or -C ₁₈ H ₃₇ , x=0.25~1.0, y=0.25~1.0.

Further, the preparation method of the composite doped phosphotungstate: weigh 0.25-1.0 mmol of cetyltrimethylammonium chloride or octadecyltrimethylammonium chloride, 0.25-1.0 mmol of Cesium carbonate and 1 mmol of phosphotungstic acid were respectively dissolved in 20 ml of deionized water; Slowly add ammonium chloride solution to phosphotungstic acid solution, and then continue to slowly add cesium carbonate solution to gradually form a white precipitate; after the dropwise addition, continue to stir for 0.5 h, and then let it stand for 1 h. After the white precipitate is filtered and separated, it is dried to obtain quaternary ammonium and cesium composite doped phosphotungstate.

Further, the mass ratio of the composite doped phosphotungstate to fructose is 3-15:100.

Further, the reaction temperature for synthesizing 5-hydroxymethylfurfural is 100-140°C.

Further, the reaction time for synthesizing 5-hydroxymethylfurfural is 20-120 minutes.

The technical solution involved in the present invention has the following advantages: (1) quaternary ammonium and cesium compound-doped phosphotungstate has both Lewis acid centers and protonic acid centers, and has strong acidity, high surface area, and high density surface acid centers, It has excellent catalytic activity for catalyzing the dehydration of fructose to prepare 5-hydroxymethylfurfural; (2) quaternary ammonium and cesium composite doped phosphotungstate has superhydrophobicity, and the affinity between the product 5-hydroxymethylfurfural and the catalyst Poor performance, which can effectively avoid the continued reaction of 5-hydroxymethylfurfural, so that the selectivity of the product 5-hydroxymethylfurfural is high; (3) The catalyst preparation process is simple, and it can be directly recycled without treatment and the separation of the reaction system is simple. The energy consumption is low, and it is convenient for industrialized production.

detailed description

Specific embodiments of the present invention will be further described in detail below. The above and other objects, features and advantages of the present invention will be apparent to those skilled in the art from the detailed description of the present invention.

Example 1:

Catalyst preparation: Weigh 0.5 mmol of cetyltrimethylammonium chloride, 0.5 mmol of cesium carbonate and 1 mmol of phosphotungstic acid and dissolve them in 20 ml of deionized water; , first slowly add the cetyltrimethylammonium chloride solution to the phosphotungstic acid solution, and then continue to slowly add the cesium carbonate solution to gradually form a white precipitate; after the dropwise addition, continue to stir for 0.5 h, and then statically Place and age for 1 h. After the white precipitate is separated by filtration and dried, the composite doped phosphotungstate with the molecular formula [(C ₁₆ H ₃₃ )N(CH ₃ ) ₃ ] _0.5 Cs _0.5 H ₂ PW ₁₂ O ₄₀ can be obtained.

Example 2:

Catalyst preparation: the preparation process is the same as in Example 1, only the addition of cesium carbonate is changed to 1 mmol, and the molecular formula can be obtained as [(C ₁₆ H ₃₃ )N(CH ₃ ) ₃ ] _0.5 Cs ₁ H _1.5 PW ₁₂ O ₄₀ Composite doped phosphotungstate.

Example 3:

Catalyst preparation: the preparation process is the same as in Example 1, only the addition of cesium carbonate is changed to 0.25 mmol, and the molecular formula can be obtained as [(C ₁₆ H ₃₃ )N(CH ₃ ) ₃ ] _0.5 Cs _0.25 H _2.25 PW ₁₂ O ₄₀ Composite doped phosphotungstate.

Example 4:

Preparation of the catalyst: the preparation process is the same as in Example 1, only the addition of cetyltrimethylammonium chloride is changed to 1 mmol, and the molecular formula can be obtained as [(C ₁₆ H ₃₃ )N(CH ₃ ) ₃ ] ₁ Cs _0.5 H _1.5 PW ₁₂ O ₄₀ compound doped phosphotungstate.

Example 5:

Preparation of the catalyst: the preparation process is the same as in Example 1, only the addition of cetyltrimethylammonium chloride is changed to 0.25mmol, and the molecular formula can be obtained as [(C ₁₆ H ₃₃ )N(CH ₃ ) ₃ ] _0.25 Compound-doped phosphotungstate of Cs _0.5 H _2.25 PW ₁₂ O ₄₀ .

Embodiment 6:

Preparation of the catalyst: the preparation process is the same as in Example 1, only cetyltrimethylammonium chloride is replaced by octadecyltrimethylammonium chloride, and the molecular formula can be obtained as [(C ₁₈ H ₃₇ )N(CH ₃ ) ₃ ] _0.5 Cs _0.5 H ₂ PW ₁₂ O ₄₀ composite doped phosphotungstate.

Embodiment 7:

Add 1 g of fructose, 20 g of N,N-dimethylformamide and 0.1 g of [(C ₁₆ H ₃₃ )N(CH ₃ ) ₃ prepared in Example 1 into a reactor equipped with a thermometer and a reflux condenser. ] _0.5 Cs _0.5 H ₂ PW ₁₂ O ₄₀ catalyst, start stirring, raise the temperature to 120°C, and react for 60 minutes. After the reaction system was cooled to room temperature, it was centrifuged and the filtrate was detected by liquid chromatography. The product yields are shown in Table 1.

Embodiment 8:

Using the same reaction conditions and detection methods as in Example 7, only changing the catalyst to [(C ₁₆ H ₃₃ )N(CH ₃ ) ₃ ] _0.5 Cs ₁ H _1.5 PW ₁₂ O ₄₀ prepared in Example 2, the product was obtained Rates are shown in Table 1.

Embodiment 9:

Using the same reaction conditions and detection methods as in Example 7, only changing the catalyst to [(C ₁₆ H ₃₃ )N(CH ₃ ) ₃ ] _0.5 Cs _0.25 H _2.25 PW ₁₂ O ₄₀ prepared in Example 3, the product was obtained Rates are shown in Table 1.

Example 10:

Using the same reaction conditions and detection methods as in Example 7, only changing the catalyst to [(C ₁₆ H ₃₃ )N(CH ₃ ) ₃ ] ₁ Cs _0.5 H _1.5 PW ₁₂ O ₄₀ prepared in Example 4, the product was obtained Rates are shown in Table 1.

Example 11:

Using the same reaction conditions and detection methods as in Example 7, only changing the catalyst to [(C ₁₆ H ₃₃ )N(CH ₃ ) ₃ ] _0.25 Cs _0.5 H _2.25 PW ₁₂ O ₄₀ prepared in Example 5, the product was obtained Rates are shown in Table 1.

Example 12:

Using the same reaction conditions and detection methods as in Example 7, only changing the catalyst to [(C ₁₈ H ₃₇ )N(CH ₃ ) ₃ ] _0.5 Cs _0.5 H ₂ PW ₁₂ O ₄₀ prepared in Example 6, the product was obtained Rates are shown in Table 1.

Example 13:

Using the same reaction conditions and detection method as in Example 7, only the amount of catalyst was changed to 0.03g, and the product yield is shown in Table 1.

Example 14:

Using the same reaction conditions and detection method as in Example 7, only the amount of catalyst was changed to 0.15g, and the product yield is shown in Table 1.

Example 15:

Using the same reaction conditions and detection methods as in Example 7, only changing the reaction temperature to 100°C, the product yields are shown in Table 1.

Example 16:

Using the same reaction conditions and detection methods as in Example 7, only changing the reaction temperature to 140°C, the product yields are shown in Table 1.

Example 17:

Using the same reaction conditions and detection methods as in Example 7, only changing the reaction time to 20 minutes, the product yields are shown in Table 1.

Example 18:

Using the same reaction conditions and detection methods as in Example 7, only changing the reaction time to 120 minutes, the product yields are shown in Table 1.

Example 19:

The catalyst used in Example 7 was centrifuged without any treatment and used for the next batch of cyclic reactions. The reaction conditions and detection methods of the cyclic reactions were the same as in Example 7. After 10 times of recycling, the product was recovered. Rates are shown in Table 1.

Comparative example 1:

Using the same reaction conditions and detection methods as in Example 7, only changing the catalyst to [(C ₁₆ H ₃₃ )N(CH ₃ ) ₃ ] ₁ H ₂ PW ₁₂ O ₄₀ , the product yields are shown in Table 1.

Comparative example 2:

Using the same reaction conditions and detection methods as in Example 7, only changing the catalyst to Cs ₁ H ₂ PW ₁₂ O ₄₀ , the product yields are shown in Table 1.

Table 1: Product yields of Examples and Comparative Examples.

According to the results in Table 1, the quaternary ammonium and cesium complex-doped phosphotungstate involved in the present invention have excellent catalytic performance in the reaction of fructose dehydration to 5-hydroxymethylfurfural, and its catalytic activity is better than that of traditional single-type ions Doped with phosphotungstate, the activity of the catalyst did not decrease significantly after 10 times of repeated use. In addition, the catalyst is easy to separate, and high product yields are obtained under mild conditions.

It should be understood that although the present invention has been clearly described through the above embodiments, those skilled in the art can make various corresponding changes and modifications according to the present invention without departing from the spirit and essence of the present invention. But these corresponding changes and amendments should all belong to the protection scope of the claims of the present invention.

Claims (4)

1. A method for the catalytic synthesis of 5-hydroxymethylfurfural by composite doping phosphotungstate, characterized in that, using composite doping phosphotungstate as a catalyst, in N,N-dimethylformamide solvent by Fructose is dehydrated to synthesize 5-hydroxymethylfurfural, and the structural formula of the composite doped phosphotungstate is: Wherein, R=-C ₁₆ H ₃₃ or -C ₁₈ H ₃₇ , x=0.25~1.0, y=0.25~1.0. 2. the method for catalytic synthesis of 5-hydroxymethylfurfural according to claim 1, is characterized in that, the mass ratio of described composite doping phosphotungstate and fructose is 3～15: 100. 3. the method for catalytic synthesis 5-hydroxymethylfurfural according to claim 1, is characterized in that, described temperature of reaction is 100～140 ℃. 4. The method for catalytically synthesizing 5-hydroxymethylfurfural according to claim 1, characterized in that, the reaction time is 20 to 120 minutes.