CN108187744B - A kind of method for catalyzing synthesis of furfural ethylene glycol acetal by aluminum ammonium phosphotungstate composite salt - Google Patents

Abstract

The invention relates to a method for synthesizing furfural glycol acetal by catalyzing aluminum ammonium phosphotungstate composite salt, which takes the aluminum ammonium phosphotungstate composite salt as a catalyst, and furfural and glycol are subjected to condensation reaction to generate the furfural glycol acetal, wherein the aluminum ammonium phosphotungstate composite salt has a simple structure formula as follows: (NH)₄)_xAl_yH_(3‑x‑3y)PW₁₂O₄₀Wherein x = 0.4-0.6, and y = 0.6-0.8. The aluminum ammonium phosphotungstate composite salt catalyst has the advantages of high specific surface area, high surface acid density, proper acid strength, excellent catalytic performance and high product yield. In addition, the raw materials needed by the catalyst are easy to obtain, the preparation process is simple, and the catalyst and the product are easy to separate and can be repeatedly used.

Description

A kind of method for catalyzing synthesis of furfural ethylene glycol acetal by aluminum ammonium phosphotungstate composite salt

technical field

The invention relates to a method for synthesizing furfural ethylene glycol acetal, in particular to a method for synthesizing furfural ethylene glycol acetal catalyzed by aluminum ammonium phosphotungstate composite salt, and belongs to the field of organic synthesis.

Background technique

Furfural glycol acetal is an important chemical intermediate raw material, and is widely used in food flavors and fragrances. In addition, it is a new type of low-toxicity plant growth regulator, which can promote the root growth of plants and enhance the drought and salt resistance of plants.

In the traditional production process of furfural ethylene glycol acetal, liquid acids such as concentrated sulfuric acid, hydrochloric acid and phosphoric acid are mainly used as catalysts, which are cheap and have high catalytic activity. However, there are many by-products in the reaction, and the separation and purification of the products are difficult. In addition, liquid acids such as sulfuric acid seriously corrode equipment, and produce a large amount of acid-containing wastewater, causing serious environmental pollution. In order to overcome the above defects, a series of heterogeneous catalysts for the synthesis of furfural glycol acetal have been developed at home and abroad, such as superacids, acidic ion exchange resins, heteropolyacids and supported catalysts. Among them, heteropolyacids have the characteristics of green non-toxicity, high activity and selectivity, but also have problems such as easy loss, low specific surface area and poor thermal stability. The solution to the above problems is to support heteropolyacids on porous supports or convert them into insoluble heteropolyacid salt catalysts. Compared with the supported heteropolyacid, the heteropolyacid salt catalyst is easy to prepare, and the surface acid strength and acid amount are easy to control, and are widely used in the reaction of acetal synthesis. Such as titanium silicotungstate (Yang Shuijin et al., Chemical Reaction Engineering and Technology, 2003, 19, 9-13), copper phosphotungstate (Liu Qing et al., Chemical Research, 2010, 21, 10-14), phosphotungstic acid Aluminum salts (Liu Qing et al., Industrial Catalysis, 2010, 18, 50-53), sulfonic acid functionalized ionic liquid phosphotungstate (Zhao Pingping et al., Journal of Nanjing University of Technology (Natural Science Edition), 2014, 36, 1-6 ) and so on can promote the synthesis of acetal. However, the above-mentioned single-type heteropolyacid salt catalysts still have defects such as low activity and selectivity, or poor reusability.

Therefore, the development of a green, efficient, stable and easy-to-separate heterogeneous catalyst suitable for the industrial production of furfural glycol acetal is still a technical problem that those skilled in the art need to solve urgently.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for catalyzing the synthesis of furfural ethylene glycol acetal by aluminum ammonium phosphotungstate composite salt, and the method has the advantages of high efficiency, environmental protection and easy separation of catalysts.

A method for synthesizing furfural ethylene glycol acetal catalyzed by aluminum ammonium phosphotungstate composite salt, which uses aluminum ammonium phosphotungstate composite salt as a catalyst to generate furfural ethylene glycol acetal by condensation reaction of furfural and ethylene glycol. In that, the structural formula of the aluminum ammonium phosphotungstate composite salt is: (NH ₄ ) _x A _y H _(3-x-3y) PW ₁₂ O ₄₀ , wherein, x=0.4~0.6, y=0.6~0.8 .

Further, the preparation process of the aluminum ammonium phosphotungstate composite salt catalyst comprises the steps:

(1) Mix aluminum salt, ammonium salt and phosphotungstic acid in the solution;

(2) After the reaction, the compound salt of aluminum ammonium phosphotungstate is separated and obtained.

Further, the step (1) is specifically:

The aluminum salt is added to the aqueous solution of phosphotungstic acid;

The ammonium salt was added to the aforementioned mixed solution.

Further, the aluminum salt is aluminum sulfate or aluminum nitrate.

Further, the ammonium salt is ammonium carbonate or ammonium nitrate.

Further, the ratio of the amount of furfural to ethylene glycol is 1:1~3.

Further, the mass ratio of catalyst to furfural is 1-3:100.

Further, the temperature of the condensation reaction is 90-110°C.

Further, the time of the condensation reaction is 1 to 5 hours.

The technical solution provided by the present invention has the following advantages: (1) The specific surface area and surface acid density of the aluminum ammonium phosphotungstate composite salt catalyst involved in the present invention are relatively high, and have suitable acid strength, which can not only promote furfural ethylene glycol The high-efficiency synthesis of acetal avoids the increase of by-products caused by excessive acid strength, so that it has excellent catalytic performance and high product yield; (2) The raw materials required for the catalyst are easily available, inexpensive, simple in the preparation process, and catalytic efficiency. The catalyst is easy to separate from the product, the catalyst can be reused, and it is suitable for large-scale application.

Detailed ways

The 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:

Preparation of catalyst: Weigh 0.25 mmol of ammonium carbonate, 0.7 mmol of aluminum nitrate and 1 mmol of phosphotungstic acid and dissolve them in 20 ml of deionized water respectively; In the phosphotungstic acid solution, react for 0.5 hours, and then slowly add ammonium carbonate solution dropwise to gradually form a white precipitate; after the dropwise addition, continue to stir the reaction for 0.5 hours, let stand for 1 hour, and the precipitate is separated by filtration and dried. The aluminum ammonium phosphotungstate compound salt with the molecular formula of (NH ₄ ) _0.5 Al _0.7 H _0.4 PW ₁₂ O ₄₀ can be obtained.

Example 2:

Preparation of catalyst: the preparation process is the same as that of Example 1, except that the addition amount of ammonium carbonate is changed to 0.2 mmol, and the addition amount of aluminum nitrate is changed to 0.8 mmol, and the molecular formula can be obtained as (NH ₄ ) _0.4 Al _0.8 H _0.2 PW ₁₂ O ₄₀ ammonium phosphotungstate complex salt.

Example 3:

Preparation of catalyst: the preparation process is the same as that in Example 1, except that the addition amount of ammonium carbonate is changed to 0.3 mmol, and the addition amount of aluminum nitrate is changed to 0.6 mmol, and the molecular formula can be obtained as (NH ₄ ) _0.6 Al _0.6 H _0.6 PW ₁₂ O ₄₀ ammonium phosphotungstate complex salt.

Example 4:

Preparation of catalyst: the preparation process is the same as in Example 1, except that ammonium carbonate is changed to 0.25 mmol ammonium nitrate, and aluminum nitrate is changed to 0.35 mmol aluminum sulfate to obtain phosphorus with the molecular formula (NH ₄ ) _0.5 Al _0.7 H _0.4 PW ₁₂ O ₄₀ Aluminum ammonium tungstate complex salt.

Example 5:

9.6 g furfural (0.1 mol), 7.5 g ethylene glycol (0.12 mol) and 0.145 g (NH ₄ ) _0.5 prepared in Example 1 were added to a reactor equipped with a thermometer, stirring device, condenser tube and water separating device. Al _0.7 H _0.4 PW ₁₂ O ₄₀ catalyst, start stirring, heat up to 100 °C, start timing when reflux begins to appear in the condenser tube, and react for 2 h. After the reaction system was cooled to room temperature, it was separated by filtration, and the filtrate was quantitatively detected by gas chromatography. The yield of furfural ethylene glycol acetal was 95.5%.

Example 6:

Using the same reaction conditions and detection method as in Example 5, only changing the catalyst to (NH ₄ ) _0.4 Al _0.8 H _0.2 PW ₁₂ O ₄₀ prepared in Example 2, the yield of furfural ethylene glycol acetal was 90.6% .

Example 7:

Using the same reaction conditions and detection method as in Example 5, only changing the catalyst to (NH ₄ ) _0.6 Al _0.6 H _0.6 PW ₁₂ O ₄₀ prepared in Example 3, the yield of furfural ethylene glycol acetal was 93.7% .

Example 8:

Using the same reaction conditions and detection method as in Example 5, only changing the catalyst to (NH ₄ ) _0.5 Al _0.7 H _0.4 PW ₁₂ O ₄₀ prepared in Example 4, the yield of furfural ethylene glycol acetal was 95.3% .

Example 9:

Using the same reaction conditions and detection method as in Example 5, only the amount of ethylene glycol was changed to 6.2 g (0.1 mol), the reaction temperature was changed to 90 °C, and the yield of furfural ethylene glycol acetal was 83.6%.

Example 10:

Using the same reaction conditions and detection method as in Example 5, only the amount of ethylene glycol was changed to 18.6 g (0.3 mol), the reaction temperature was changed to 110 °C, and the yield of furfural ethylene glycol acetal was 97.9%.

Example 11:

Using the same reaction conditions and detection method as in Example 5, only the amount of catalyst was changed to 0.096 g, the reaction time was changed to 5 h, and the yield of furfural ethylene glycol acetal was 97.6%.

Example 12:

Using the same reaction conditions and detection method as in Example 5, only the amount of catalyst was changed to 0.288 g, the reaction time was changed to 1 h, and the yield of furfural ethylene acetal was 90.3%.

Example 13:

The catalyst used in Example 5 was filtered and separated without any treatment, and used for the next batch of cyclic reaction. The reaction conditions and detection method of the cyclic reaction were the same as in Example 5. After 10 times of recycling, furfural ethyl acetate The yield of diol acetal was 92.5%.

Comparative Example 1:

Using the same reaction conditions and detection method as in Example 5, only changing the catalyst to (NH ₄ ) _2.6 H _0.4 PW ₁₂ O ₄₀ , the yield of furfural glycol acetal was 87.5%.

Comparative Example 2:

Using the same reaction conditions and detection method as in Example 5, only changing the catalyst to Al _2.6/3 H _0.4 PW ₁₂ O ₄₀ , the yield of furfural ethylene glycol acetal was 83.9%.

According to the results of Examples 5-13 and Comparative Examples 1-2, the aluminum ammonium phosphotungstate complex salt involved in the present invention has very excellent catalytic performance for the condensation reaction of synthesizing furfural ethylene glycol acetal, and its catalytic performance is better than traditional The single-type ammonium phosphotungstate and aluminum phosphotungstate did not show a significant decrease in the activity of the catalyst after 10 repeated uses. In addition, the catalyst preparation process is simple, and the required raw materials are readily available and inexpensive. Therefore, the technical solution involved in the present invention is suitable for industrial application.

It should be understood that although the present invention has been clearly described by 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. However, these corresponding changes and corrections should all belong to the protection scope of the claims of the present invention.

Claims (5)

1. a method for catalyzing and synthesizing furfural ethylene glycol acetal with aluminum ammonium phosphotungstate composite salt, taking the aluminum ammonium phosphotungstate composite salt as a catalyst, and generating furfural ethylene glycol acetal by the condensation reaction of furfural and ethylene glycol, It is characterized in that, the structural formula of the aluminum ammonium phosphotungstate composite salt is: (NH ₄ ) _x A _y H _(3-x-3y) PW ₁₂ O ₄₀ , wherein, x=0.4～0.6, y=0.6 ～0.8, the ratio of the amount of furfural to ethylene glycol in the condensation reaction is 1:1～3, the mass ratio of catalyst and furfural is 1～3:100, the reaction temperature is 90～110 ℃, and the reaction time is 1 to 5 hours. 2. the method for catalyzing synthesis of furfural ethylene glycol acetal according to claim 1, is characterized in that, the preparation process of described phosphotungstic aluminum ammonium composite salt catalyst comprises the steps: (1) mixing aluminum salt, ammonium salt and phosphotungstic acid in solution; (2) After the reaction, the compound salt of aluminum ammonium phosphotungstate is separated and obtained. 3. the method for catalytic synthesis of furfural ethylene glycol acetal according to claim 2, is characterized in that, described step (1) is specially: The aluminum salt is added to the aqueous solution of phosphotungstic acid; The ammonium salt was added to the aforementioned mixed solution. 4. the method for catalytic synthesis of furfural glycol acetal according to claim 2, is characterized in that, described aluminium salt is aluminium sulfate or aluminium nitrate. 5. the method for catalytic synthesis of furfural ethylene glycol acetal according to claim 2, is characterized in that, described ammonium salt is ammonium carbonate or ammonium nitrate.