KR20140062732A - A method to dehydrate polyols - Google Patents

Abstract

The present invention relates to a method for dehydrating polyols such as sorbitol, mannitol, xylitol, and arabinitol and, more specifically, to a method for dehydrating polyols capable of achieving a high dehydration conversion rate, high selectivity, and high yields by using a sulfated solid catalyst. The method for dehydrating the polyol according to the present invention is a very economical method since the sulfated solid catalyst is reusable by recovering after used in the dehydration reaction of the polyols.

Description

Description of the Related Art A method for dehydration polyols

The present invention relates to a process for dehydrating a polyol, and more particularly to a technique for obtaining a desired product by a simple process using a sulfated solid catalyst in the dehydration reaction of a polyol.

The polyol may be defined as sorbitol, mannitol, xylitol, arabinitol, and mixtures thereof, and may be defined primarily as a polyol of hexanediol and pentanediol, and mixtures thereof are also possible .

Polyols are obtained from renewable biomass, and dehydration reactions can provide useful chemical intermediates such as isobarbide. This dehydration reaction can proceed in the presence of various catalysts and is a very important reaction commercially. As the catalyst, a solid acid catalyst such as heteropoly acid (USP 7615652, 7772412), cation exchange resin (USP 7122661, 7728156) and zeolite (USP 7615652) as well as liquid acid such as sulfuric acid It is known that it can be used.

Products such as isobarbide obtained by dehydration of a polyol such as sorbitol are used as an additive in the production of polymers such as polyethylene terephthalate, and are used as a copolymer for polymers and for medicines (such as hydrocephalus, urination and glaucoma treatment) It is a useful compound. Especially, polyol such as sorbitol is a material derived from biomass that can be regenerated in nature. Therefore, it is considered that the necessity and importance of technology development is very high.

Thus, it has been desired to develop a catalyst having low activity and yield, which is a catalyst having low corrosivity and low risk, such as isobarbide, which is useful in various fields. Up to now, a liquid acid catalyst such as sulfuric acid has been mainly used, And the like, are not corrosive and safe, but have problems in reactivity, selectivity and yield.

Therefore, it is required to study the catalyst and the process for dehydration reaction having high yield and selectivity even in the case of low corrosivity, low risk and mild conditions.

U.S. Patent No. 7615652, United States Patent 7772412 United States Patent 7122661 United States Patent 7728156

The present invention provides a method for dehydrating polyols having a low yield and a high conversion rate while having low corrosiveness and low risk.

More specifically, the present invention provides an effective method for dehydrating a polyol which can produce a product usable in various applications.

The present invention relates to a method for dehydrating a polyol from which a product usable for various uses can be obtained,

a) mixing a polyol which is a mixture of one or more selected from sorbitol, mannitol, xylitol and arabinitol and a sulfurated solid catalyst;

b) heating and dehydrating the mixture of steps;

c) cooling and separating the reactant in step b) and drying to obtain a product.

The support of the sulfurated solid according to an embodiment of the present invention may be titania, zirconia or a mixture thereof.

The weight ratio of polyol: sulfated solid catalyst according to one embodiment of the present invention may be 1: 0.001 to 0.5.

The heating according to one embodiment of the present invention may be performed at 100 to 300 ° C.

A sulfated solid catalyst according to an embodiment of the present invention comprises reacting a transition metal hydroxide or a transition metal alkoxide with sulfuric acid,

Separating the reactants in the above step and drying and firing them to obtain a sulfurized solid catalyst, and the transition metal may be zirconia, titania or a mixture thereof.

In the sulfated solid catalyst according to an embodiment of the present invention, the alkoxide functional group may be methoxide, ethoxide, propoxide, isopropoxide, butoxide or a mixture thereof, Min to 24 hours.

The sulfuric acid used in the preparation of the sulfurated solid catalyst according to an embodiment of the present invention may have a concentration of 0.002 to 1.5 moles.

The method of dewatering poly according to an embodiment of the present invention may further include a step of reducing the pressure of the reactor containing the mixture of the step before step b).

The dehydration process of the polyol according to the present invention proceeds with a simple process using a sulfurized solid catalyst having low corrosiveness and low risk.

Further, the dehydration method of the polyol according to the present invention is a simple and effective dehydration reaction by using a sulfurized solid catalyst, in particular, titania, zirconia or a mixture thereof as a support, thereby achieving high dehydration conversion, high product selectivity and high yield It is a very effective way to be.

In addition, the dehydration method of the polyol according to the present invention is a very economical method because the sulfurized solid catalyst is used for the dehydration reaction of the polyol, and then recovered and reused.

The present invention relates to a process for dehydration of a polyol, the process for producing a polyol of the present invention comprises the steps of: a) mixing a polyol which is a mixture of one or two selected from sorbitol, mannitol, xylitol and arabinitol and a sulfurated solid catalyst ; b) heating the mixture to dehydrate, and c) separating and drying the reactant in step b) to obtain a product.

The dehydration reaction generally proceeds easily in the presence of an acid catalyst, and sulfuric acid is mainly used, but sulfuric acid is not only dangerous but also highly corrosive. Studies on the use of solid acids in this respect have been continuing, suggesting the use of catalysts such as heteropoly acids, cation exchange resins, and zeolites, but they are unsatisfactory in terms of reaction activity, selectivity and yield.

However, the dehydration method of the polyol of the present invention is easy to handle using a sulfurized solid catalyst having no corrosiveness and danger, and has high dehydration conversion and selectivity.

The sulfuric acid solid catalyst according to an embodiment of the present invention can obtain the performance that is obtained from sulfated solid using titania and zirconia as support, namely, sulfated titania and sulfated zirconia, To enhance selectivity and yield, it is more preferable to use titania as a support. Sulfurized solid catalysts, especially sulfated titania, have high dehydration conversion, high product selectivity and excellent regeneration, so that the conversion and isobaride selectivity are stable even after three regeneration cycles, In effect can be obtained.

Also, the reactivity can be further improved by using the sulfurized solid catalyst while simultaneously reducing the pressure of the reactor containing the sulfurized solid catalyst and the polyol.

More preferably, in the dehydration reaction of the polyol, a solid catalyst selected from among sulfurized solid catalysts selected from the group consisting of sulfurated titanic acid, sulfurized zirconia or a mixture thereof is used at a pressure in the range of 0.05 to 20 bar, more preferably 0.1 to 1 bar High reactivity, high dehydration conversion rate and high yield can be obtained.

The product produced by the dehydration process of the polyol according to the present invention is a major target product, although any dehydration product is possible, but one water molecule or two water molecules are missing per polyol molecule. For example, sorbitol dehydration can be a representative product of sorbitan and isosorbide from which one or two water molecules have been removed, respectively.

The dehydration reaction according to an embodiment of the present invention may be performed at 100 to 300 ° C. The reaction used may be electric heating or microwave heating. The microwave heating is preferable because the reaction time can be shortened. When the reactor containing the reaction mixture is decompressed and the temperature is raised to a predetermined temperature It is preferable to proceed the reaction in the thus-reached bath.

The temperature of dehydration is 100 ~ 300 ^o be carried out in C, but the reaction temperature is too to low, the reaction speed is too slow, impractical and too high, the side reaction is generated considering the side and a polyol having a boiling point of which the reaction efficiency decreases the boiling point of the polyol The temperature of 150 to 220 ^° C is preferable.

The dehydration reaction is preferably carried out at 0.1 to 1 bar which can improve the reaction rate and efficiency by removing water as a by-product. However, it is possible to increase the reaction rate by removing water and to suppress the generation of color-inducing impurities So that hydrogen can be flowed to further increase the efficiency.

The dehydration reaction can be carried out continuously as well as batchwise. The batch type dehydration reactor is suitable for dehydration of a small amount of polyol because the production rate is low per hour. The dehydration reaction time is suitably about 1 minute to 100 hours in the case of the batch type, and if the dehydration reaction time is too long, impurities are easily incorporated and energy efficiency is low. If the dehydration reaction time is too short, the dehydration efficiency is low. The dehydration reaction time is more preferably from 1 minute to 24 hours. The residence time of the continuous dehydration reactor is suitably about 1 minute to 1 hour. If the residence time is too long, the productivity is low and the side reaction is likely to occur. If the residence time is too short, the conversion rate of the dehydration reaction is low. A residence time of 1 to 20 minutes is more suitable. During the batch reaction, the reactants may be stirred, and the stirring speed may be 100-1000 rpm, but it may be carried out without stirring.

The dehydration reaction can be carried out without a solvent, and the presence of a solvent facilitates mixing and temperature control of the reactants. The solvent can be any organic or inorganic solvent, but any solvent can be used as long as it is an inexpensive, especially easy-to-obtain, solvent that can partially dissolve polyols such as ethanol, methanol, ethyl ether and chloroform.

The amount of the catalyst selected from the sulfurized solid catalyst, the sulfated titania, the sulfated zirconia or the mixture thereof in accordance with an embodiment of the present invention is in the range of 1: 0.001 to 0.5 However, when the concentration of the sulfurized solid catalyst is too low, the reaction rate is too low to be unrealistic. When the concentration is too high, the efficiency of the catalyst is low and the side reaction is likely to occur. Preferably from 1: 0.01 to 0.05.

The separation in step d) according to an embodiment of the present invention can be carried out as long as it is carried out in a conventional chemical reaction. Preferably, the solid catalyst and the product can be separated by filtration, To remove water. The separated solid catalyst after being used in the reaction can be used by washing with a solvent such as water or acetone, and can be reused after firing for 1 to 10 hours at 200 to 600 ° C after washing. The sulfurized solid catalyst of the present invention is economically effective because it can be reused because it is not lost its activity even if it is separated and reused after repeated use.

A sulfated solid catalyst according to an embodiment of the present invention comprises reacting a transition metal hydroxide or a transition metal alkoxide with sulfuric acid,

And separating and drying and firing the reactants in the above step to obtain a sulfurized solid catalyst.

The transition metal according to an embodiment of the present invention may be zirconia, titania or a mixture thereof, and the alkoxide may be a methoxide, an ethoxide, a propoxide, an isopropoxide, a butoxide or a mixture thereof.

In the preparation of the sulfurized solid catalyst according to an embodiment of the present invention, the reaction may be carried out for 1 to 6 hours, and the reaction temperature may be adjusted by adjusting the concentration and amount of the transition metal hydroxide or transition metal alkoxide and sulfuric acid, , But it is also possible at room temperature, which is a milder condition.

In the preparation of the sulfurized solid catalyst according to an embodiment of the present invention, drying may be carried out at room temperature to 150 ° C for 12 to 36 hours, Can be carried out for 24 hours.

The sulfuric acid used in the preparation of the sulfurized solid catalyst according to an embodiment of the present invention may have a concentration of 0.0001 to 1.5 moles, preferably 0.001 to 0.5 moles in terms of efficient sulfurization of the solid catalyst.

Hereinafter, the present invention will be described in more detail in the following non-limiting examples, but the claims of the present invention are not limited to these examples. Unless otherwise defined, technical terms and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In the following description, And a description of the known function and configuration will be omitted.

[Example 1] Preparation of sulfated zirconia

A mixture of 1.0 g of zirconium (IV) hydroxide and 20.0 mL of aqueous sulfuric acid solution (0.002, 0.02, 0.05 and 0.1 M) was well stirred at room temperature for 5 hours and then the solid product was centrifuged and dried at 100 ^° C for 24 hours . The dried solid product was pulverized into a fine powder and calcined at 600 ^° C for 5 hours. The solid catalyst obtained is named SZ-n, where n represents the molarity of the aqueous sulfuric acid solution used in the sulfation.

[Example 2] Production of sulfurated titania

12.5 mL of titanium isopropoxide was added to 100 mL of 1-propanol. After thoroughly mixing with magnetic stirring, 3.2 mL of a 1 M aqueous sulfuric acid solution was added dropwise, followed by stirring for 4 hours. After that, a white gel was obtained, which was filtered, washed, and then dried at 100 ^° C for 24 hours. Finally, the catalyst was calcined at 400 ^° C for 1 hour to obtain a sulfurized titania catalyst.

[Example 3] Dehydration reaction

10.0 g of sorbitol dissolved at 120 < ⁰ > C was added to a glass reactor and 0.2 g of the sulfurated titania catalyst prepared in Example 2 was added to the reactor. A cooler was connected to the upper part of the reactor while stirring the reaction product, and the reactor pressure was reduced to 0.3 bar by using a vacuum pump. After raising the reaction temperature to soak in a silicone oil maintained a glass reactor to 210 ^o C to rapidly 210 ^o C was initiated and the reaction After the reaction for 2 hours cooled and the reaction product was filtered at a temperature of about 100 ^o C was removed of the solid catalyst The resulting product was dried at 110 < ⁰ > C to remove water. RI detector and Asahipak NH2P-50 4E (No. N712004) columns. The reaction conditions and results are summarized in Table 1. A complete dehydration reaction proceeded with a reaction time of 2 hours using a sulfurized titania catalyst, and the dehydration conversion rate was 100% and the yield of isovoid formation was 70.3%.

[Example 4]

The dehydration reaction was carried out in the same manner as in Example 3, except that the reaction time was maintained at 4 hours instead of 2 hours. The results are summarized in Table 1. The dehydration conversion of the sorbitol dehydration reaction was 100% and the yield of isovoid was 75.3%.

[Example 5]

The dehydration reaction was carried out in the same manner as in Example 3 except that sulfated zirconia (SZ-0.02) was used instead of sulfur dioxide titania as a catalyst and the reaction time was maintained for 3 hours instead of 2 hours. The results are summarized in Table 1. The dehydration conversion of sorbitol dehydration was 100% and the yield of isovoid was 45.1.

[Example 6]

The dehydration reaction was carried out in the same manner as in Example 3, except that sulfated zirconia (SZ-0.05) was used instead of sulfur dioxide titania as a catalyst and the reaction time was maintained for 3 hours instead of 2 hours. The results are summarized in Table 1. The dehydration conversion of sorbitol dehydration was 100% and the yield of isovoid was 61.7.

[Example 7]

The dehydration reaction was carried out in the same manner as in Example 3, except that sulfated zirconia (SZ-0.1) was used instead of sulfur dioxide titania as a catalyst and the reaction time was maintained for 3 hours instead of 2 hours. The results are summarized in Table 1. The dehydration conversion of sorbitol dehydration was 100% and the yield of isovoid was 62.2%.

[Example 8]

The dehydration reaction was carried out in the same manner as in Example 3, except that sulfurized zirconia (SZ-0.05) was used instead of sulfur dioxide titanate as a catalyst. The results are summarized in Table 1. The dehydration conversion of the sorbitol dehydration reaction was 100% and the yield of isovoid was 61.1.

[Example 9]

The dehydration reaction was carried out in the same manner as in Example 3, except that sulfuric acid zirconia (SZ-0.05) calcined at 400 ^° C for 7 hours was used instead of the catalyst titanated sulfuric acid three times in the dehydration reaction . The reaction results are summarized in Table 1. The dehydration conversion of sorbitol dehydration was 100% and the yield of isovoid was 44.0%.

[Example 10]

The reaction temperature was 210 ^o C to 200 ^o instead proceeds to dehydration reaction in the same manner as in Example 3 except that the C and the results are summarized in Table 1 below. The dehydration conversion of the sorbitol dehydration reaction was 100% and the yield of isovoid was 60.1.

[Example 11]

After 3 reaction, the reaction temperature in the as dehydration to 200 ^o C in place of 210 ^o C, except that the sulfated titania for 3 hours and baked at 400 ^o C is proceeding a dehydrating reaction in the same manner as in Example 3 Respectively. The results are summarized in Table 1. The dehydration conversion of sorbitol dehydration was 100% and the yield of isovoid was 56.0%. It was found that the dehydration reaction proceeded successfully even though the use was repeated four or more times.

[Example 12]

The dehydration reaction was carried out in the same manner as in Example 6, except that microwave was applied instead of a typical electric heating as a reaction heat source and the reaction was carried out under autogenous pressure without vacuum treatment. The results are summarized in Table 1. The dehydration conversion of sorbitol dehydration reaction was 100% and the yield of isovoid was 60.3%.

[Comparative Example 1]

The dehydration reaction was carried out in the same manner as in Example 5, except that zirconia which was not subjected to sulfation was used as a catalyst. The results are summarized in Table 1. The dehydration conversion of sorbitol dehydration reaction was 21.1% and the yield of isovoid was 0%.

Conditions and results of dehydration reaction of polyol (reactant: sorbitol 10.0 g) Examples and Comparative Examples
reaction
Temperature
( ^o C) reaction
time
(time) catalyst*
(0.2 g) Heating method Sorbitol
Conversion Rate
(%) Isoboride yield (%) Example 3 210 2 S-TiO ₂ Electric heating 100 70.3 Example 4 210 4 S-TiO ₂ Electric heating 100 75.3 Example 5 210 3 S-ZrO ₂ (0.02) Electric heating 100 45.1 Example 6 210 3 S-ZrO ₂ (0.05) Electric heating 100 61.7 Example 7 210 3 S-ZrO ₂ (0.1) Electric heating 100 62.2 Example 8 210 2 S-ZrO ₂ (0.05) Electric heating 100 61.1 Example 9 210 2 S-ZrO ₂ (0.05) recovered after 3 times of use, Electric heating 100 44.0 Example 10 200 2 S-TiO ₂ Electric heating 100 60.1 Example 11 200 2 S-TiO ₂ recovered after 3 times of use Electric heating 100 56.0 Example 12 210 3 S-ZrO ₂ (0.05) Microwave heating 100 60.3 Comparative Example 1 210 3 ZrO ₂ Electric heating 21.1 0

* S means a sulfurized catalyst. S-ZrO ₂ The numbers in parentheses after the symbol indicate the molar concentration of sulfuric acid used in the production.

From the results of the examples and the comparative examples, it can be seen from the results of the examples that the dehydration method of the polyol performed with the sulfuric acid solid catalyst according to the present invention does not involve the problem of corrosion and safety without using liquid acid such as sulfuric acid, Id can be obtained in high yield.

Particularly, sulfated titania had a higher yield of isobarbide than sulfated zirconia, and when recovered after 3 times of use, sulfated titania obtained isobarbide with higher yield than sulfated zirconia .

On the other hand, from the results of the comparative example, it is found that the dehydration reaction of the polyol using the non-sulfated solid has a low dehydration conversion and a very low yield of isobaride.

Polyols such as sorbitol, mannitol, xylitol and arabinitol are derived from biomass and dehydrated products are important for comonomers and medicines, so their simple, easy and successful dehydration reaction is very important.

Claims (10)

a) mixing a polyol which is a mixture of one or more selected from sorbitol, mannitol, xylitol and arabinitol and a sulfurated solid catalyst;
b) heating and dehydrating the mixture of steps;
c) cooling and separating the reactant in step b) and drying to obtain a product. The method according to claim 1,
The method of dehydration of polyols which are titania, zirconia or mixtures thereof as a support. 3. The method of claim 2,
Wherein the weight ratio of polyol: sulfated solid catalyst is 1: 0.001 to 0.5. The method according to claim 1,
And heating is carried out at 100 to 300 ° C. The method according to claim 1,
further comprising the step of reducing the pressure of the reactor containing the mixture of the step before step b). The method according to claim 1,
The sulfurated solid catalyst comprises reacting a transition metal hydroxide or transition metal alkoxide with sulfuric acid;
Separating the reactants in the above step and drying and firing to obtain a sulfurized solid catalyst. The method according to claim 6,
Wherein the transition metal is zirconia, titania or a mixture thereof. The method according to claim 6,
Wherein the alkoxide is a methoxide, ethoxide, propoxide, isopropoxide, butoxide or mixtures thereof. The method according to claim 6,
And firing is carried out at 300 to 700 ° C for 30 minutes to 24 hours. The method according to claim 6,
Wherein the concentration of sulfuric acid is 0.002 to 1.5 moles.