KR20160044777A - Method of Preparing Anhydrosugar Alcohols by Using Nonevaporated Catalyst - Google Patents

Abstract

More particularly, the present invention relates to a method for preparing anhydrosugar alcohol by dehydrating sugar alcohol in the presence of a catalyst capable of maintaining its activity without evaporation of the catalyst during the reaction. The process for preparing anhydrosugar alcohol according to the present invention can increase the yield of anhydrosugar alcohol by dehydrating sugar alcohol in the presence of a catalyst capable of maintaining its activity without evaporation of the catalyst during the reaction.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for preparing anhydrous alcohol by using an evaporation catalyst,

More particularly, the present invention relates to a method for preparing anhydrosugar alcohol by dehydrating sugar alcohol in the presence of a catalyst capable of maintaining its activity without evaporation of the catalyst during the reaction.

With the increase of global energy demand and the depletion of traditional energy sources, we are accelerating the development of alternative energy. Among them, biomass is a quantitative living resource that can be regenerated, which is attracting much attention.

Isosorbide (C ₆ H ₁₀ O ₄ ), which is produced by dehydration of sorbitol (C ₆ H ₁₄ O ₆ ) from biomass-based industrial raw materials, replaces bisphenol A (BPA) (PC, Polycarbonate), an epoxy monomer, or an eco-friendly plasticizer. In other words, isosoboid is a substance obtained through a simple dehydration process of sorbitol, and is attracting attention as a monomer required for synthesis of a next generation high performance, environment-friendly material that can replace the existing polymer products. Much research is underway.

In general, the use of environmentally friendly raw materials is less favorable than that of raw materials for petrochemicals, while isosoboids are environmentally friendly and have superior properties over petrochemicals. In addition, isosorbide can be used as an additive to make plastic stronger and cheaper, and isosorbide in combination with nitrate is also used as a treatment for heart disease.

D-glucose (D-glucose) pretreated in biomass is hydrogenated under catalysis to produce sorbitol. This sorbitol is double dehydrated to produce isosorbide. This cyclization reaction is affected by various reaction conditions such as temperature, pressure, solvent, and catalyst.

The production method of isosobide is prepared by dehydration reaction with an inorganic acid such as sulfuric acid or hydrochloric acid. Inorganic acids such as hydrochloric acid and sulfuric acid are comparatively inexpensive and can easily produce alcohol-free alcohol. However, there is a problem that the yield of purification is decreased due to the generation of high molecular weight as a by-product. In addition, US Patent No. 6,864,378 and Korean Patent Laid-Open Publication No. 2013-0103059 disclose a technique of distilling and recovering the produced isosorbide and water to the upper portion of the reactor simultaneously with the reaction.

U.S. Patent No. 6,864,378 discloses a process in which excess water relative to sorbitol is simultaneously introduced into the reactor to recover product and excess water from the top of the reactor. In this case, there is a disadvantage that the operation ratio is increased because the step of heating and vaporizing the excessively charged water is performed.

Korean Patent Laid-Open Publication No. 2013-0103059 discloses the use of a sulfuric acid metal oxide solid acid catalyst in order to compensate for the disadvantage that the catalytic function is limited due to evaporation of sulfuric acid when sulfuric acid catalyst is used. In this case, since the reaction proceeds at a hetero phase using an expensive catalyst and using a solid acid catalyst, the contact efficiency between the catalyst and sorbitol is low, so that a reaction time of 2 to 8 hours is required There is a problem that the driving ratio increases.

Therefore, economical and efficient manufacturing method with high conversion rate and high yield of isosoboid is required, which can reduce cost, and mass production process can enlarge the demand range as an industrial product.

Accordingly, the present inventors have found that, in a decompression reaction for converting sorbitol to isosorbide, a boiling point higher than that of isosorbide enables the catalyst activity to be maintained without evaporation of the catalyst during the reaction, and the homogeneous phase It is confirmed that the yield of isosorbide can be increased economically by using a catalyst having an appropriate acidity in order to increase the contact efficiency between the catalyst and the feed and to reduce the formation of side reactants such as polymer or coke under high temperature reaction conditions Thereby completing the present invention. In addition, since the present invention uses a catalyst having a boiling point higher than that of sorbitol as well as isosobide, the produced isosorbide can be recovered by distillation simultaneously with the reaction, thereby simplifying the process and improving the overall yield .

An object of the present invention is to provide a process for preparing an alcohol-free alcohol which can economically increase the yield of alcohol-free alcohol in the conversion of sugar alcohol to alcohol-free alcohol.

In order to achieve the above object, the present invention provides a method for converting a sugar alcohol to an alcohol-free alcohol using a catalyst having the following characteristics under a high-temperature decompression condition,

(a) a boiling point at 10 mmHg of at least 160 캜;

_{(b) -3.0 <pK a <} 1.99; And

(c) reacting in a homogeneous manner, the activity of which is maintained without evaporation of the catalyst.

The method for preparing alcohol-free alcohol according to the present invention is characterized in that the contact efficiency between the catalyst and the feed is high and the production of non-alcoholic alcohol is improved by decreasing the production of side products of the polymer or coke, So that the catalyst activity can be maintained and operation cost can be reduced.

Unless otherwise defined, all technical 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 general, the nomenclature used herein is well known and commonly used in the art.

In the present invention, in the decompression reaction for converting sorbitol to isosorbide, the boiling point higher than isosorbide enables the catalyst activity to be maintained without evaporation of the catalyst during the reaction, and the reaction can be carried out in a homogeneous phase The yield of isosorbide can be increased by increasing the contact efficiency between the catalyst and the feed and by using a catalyst having an acidity suitable for reducing the formation of side reactants such as polymer or coke under high temperature reaction conditions.

Accordingly, in one aspect, the present invention relates to a method for converting a sugar alcohol to a sugar-free alcohol using a catalyst having the following characteristics under high-temperature decompression conditions, and simultaneously recovering the produced sugar-free alcohol:

(a) a boiling point at 10 mmHg of at least 160 캜;

_{(b) -3.0 <pK a <} 1.99; And

(c) reacting in a homogeneous manner, the activity of which is maintained without evaporation of the catalyst.

The present invention is characterized in converting sorbitol to isosorbide in the decompression reaction and recovering the produced isosorbide at the same time. That is, the reaction and the distillation separation are simultaneously carried out.

The catalyst according to the present invention satisfies the following conditions.

(a) Boiling point

To maintain the catalytic activity without catalyst evaporation during the reaction, a catalyst having a boiling point higher than isosoboid (160 ° C at 10 mmHg) is selected. That is, the boiling point at 10 mmHg is 160 캜 or higher.

(b) acidity (pK _a )

A catalyst having an acidity suitable for reducing the formation of byproducts such as polymers or coke at high temperature reaction conditions is used. PKa range for the yield increase is -3.0 <pK _a <1.99, and preferably range from -2.0 <pK _a <1.9 and, more preferably is in the range -1.0 <pK _a <1.9. And a pKa of -3.0 sulfuric acid, pKa of NaHSO ₄ was 1.99.

(3) homogeneous phase

A catalyst is used which increases the contact efficiency between the catalyst and the feed, reacts in a homogeneous phase under the reaction conditions, and maintains its activity without evaporation of the catalyst. For this purpose, the melting point may be 180 ° C or lower, preferably 160 ° C or lower, more preferably 140 ° C or lower, and particularly preferably 120 ° C or lower.

The catalyst may be naphthalenesulfonic acid. Specific compounds of naphthalenesulfonic acid include 2-naphthalenesulfonic acid or 1-naphthalenesulfonic acid, and these compounds are isomers which are formed by sulfonation of naphthalene. The 2-naphthalenesulfonic acid has pK _a = 0.27, mp = 91 캜, bp = 391.6 캜, and 1-naphthalenesulfonic acid has pK _a = 0.17, mp = 90 캜 and bp = 392 캜.

The temperature of the reaction may be 130 ° C to 230 ° C, preferably 150 ° C to 200 ° C. If the reaction temperature is lower than 130 ° C, the reaction time or residence time becomes very long. If the reaction temperature is higher than 230 ° C, the side reaction may be promoted and the yield may be decreased.

The pressure of the reaction may be from 1 torr to 100 torr, preferably from 5 torr to 50 torr. When the reaction pressure is less than 1 torr, there is a problem that the process operation ratio due to high vacuum is greatly increased, and when it exceeds 100 torr, the reaction rate is slow and the yield is low.

From the viewpoint of the efficiency of the process, the smaller the amount of the added catalyst, the higher the economic efficiency. The amount of the catalyst used in the present invention may be 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, And more preferably 0.2 to 3 parts by weight. When the amount of the catalyst is less than 0.01 part by weight, the dehydration reaction takes a long time. When the amount of the catalyst is more than 10 parts by weight, the production of the saccharide polymer as a by-product increases and the economical efficiency decreases due to an increase in the amount of the catalyst.

In the present invention, the sugar alcohol may be hexitol, and may be at least one selected from the group consisting of sorbitol, mannitol and iditol, preferably sorbitol, and the alcohol without sugar is isosorbide, Need, isodeside and the like, preferably isosoboid.

The process for preparing anhydrosugar alcohol according to the present invention can be carried out batchwise or continuously. Can be carried out in a continuous stirred tank reactor (CSTR), a plug flow reactor (PFR) or a batch reactor (BR).

In addition, the method for preparing an alcohol-free alcohol according to the present invention may further include a step of separating and / or purifying the product after the alcohol-free alcohol is prepared. The distillation, crystallization, and adsorption processes can be used singly or in combination of two or more for the separation and purification of the product.

Korean Patent No. 10-1079518 discloses a process for producing isosorbide using a mixed acid such as sulfuric acid, p-toluenesulfonic acid, methanesulfonic acid, methanesulfonic acid, naphthalenesulfonic acid, etc., The yield of isosorbide is low and strong acid is used as it is, which is a disadvantage of strong acid catalyst.

In addition, the patent further includes a step of neutralizing the reaction product after the dehydration reaction by adding an aqueous alkali solution before distillation, in order to separate / purify the product, while in the present invention, water and anhydrosugar alcohol Is recovered to the top of the reactor and the catalyst remains in the reactor. Therefore, in the present invention, there is an advantage that the neutralization step and the distillation step are not required, and thus the energy efficiency and the economical efficiency are excellent.

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these embodiments are for illustrative purposes only and that the scope of the present invention is not limited by these embodiments.

[Example]

Example 1

Into an autoclave reactor, 70 g of sorbitol (D-sorbitol, Aldrich) was added to the reactor, and the temperature was raised to dissolve sorbitol. Then, 0.7 g of 2-naphthalenesulfonic acid was added and stirred, The temperature was raised to 180 ° C. The isosorbide produced during the reaction for 1 hour was distilled out of the reactor at the same time as the reaction.

The reaction product was diluted 20-fold with water and analyzed by high performance liquid chromatography (HPLC, product of Algilent, Carbohydrate column). The yield of the resulting isosorbide was 77.5 mol%.

Example 2

The procedure of Example 1 was repeated except that 0.7 g of 1-naphthalenesulfonic acid was used as a catalyst in Example 1. The yield of the resulting isosorbide was 76.7 mol%.

Example 3

The procedure of Example 1 was repeated, except that 0.35 g of 2-naphthalene sulfonic acid was used as the catalyst in Example 1. The yield of the resulting isosorbide was 77.0 mol%.

Comparative Example 1

The procedure of Example 1 was repeated except that 0.7 g of sulfuric acid (H ₂ SO ₄ ) was used as the catalyst in Example 1. The yield of the resulting isosorbide was 63 mol%.

Comparative Example 2

The procedure of Example 1 was repeated except that 0.7 g of benzenesulfonic acid was used as a catalyst in Example 1. The yield of the resulting isosorbide was 27 mol%.

Comparative Example 3

The procedure of Example 1 was repeated except that 1.5 g of NaHSO ₄ catalyst was used in Example 1. The yield of the resulting isosorbide was 1 mol% or less.

Comparative Example 4

Comparative Example 1 was carried out in the same manner as in Comparative Example 1 except that a mixture of 0.7 g of naphthalene sulfonic acid (NSA) and 0.7 g of sulfuric acid (H ₂ SO ₄ ) was used as the catalyst. The yield of the resulting isosorbide was 65 mol%.

The yields of the products of Examples 1 to 3 and Comparative Examples 1 to 4 are shown in Table 1 by the following formula.

Yield = number of moles of isosorbide produced / number of moles of sorbitol added X 100

catalyst Reaction temperature (캜) Yield (mol%) Example 1 0.7 g of 2-naphthalenesulfonic acid 180 77.5 Example 2 0.7 g of 1-naphthalene sulfonic acid 180 76.7 Example 3 0.35 g of 2-naphthalene sulfonic acid 180 77.0 Comparative Example 1 0.7 g of H ₂ SO ₄ 180 63 Comparative Example 2 Benzenesulfonic acid 0.7 g 180 27 Comparative Example 3 NaHSO ₄ 1.5 g 180 1 or less Comparative Example 4 Mixed acid (NSA + H ₂ SO ₄₎ 180 65

As shown in Table 1, the yields of isosorbide prepared in Examples 1 to 3 using the catalyst according to the present invention were much better than those of Comparative Example. In Comparative Example 2, the yield of the catalyst was very low due to evaporation of the catalyst at a high reaction temperature, and the catalyst of Comparative Example 3 had a high pKa of 1.99, which resulted in a very slow reaction and a low yield. Since a pKa of -3.0 sulfuric acid, pKa of NaHSO ₄ was 1.99, in Comparative Example 3 with NaHSO ₄ was confirmed that the very low catalytic activity under the same reaction temperature.

While the present invention has been particularly shown and described with reference to specific embodiments thereof, those skilled in the art will appreciate that such specific embodiments are merely preferred embodiments and that the scope of the present invention is not limited thereto will be. Accordingly, the actual scope of the invention will be defined by the claims and their equivalents.

Claims (6)

A method of converting a sugar alcohol into a sugar-free alcohol using a catalyst having the following characteristics under a high-temperature decompression condition, and simultaneously recovering the produced sugar-free alcohol:
(a) a boiling point at 10 mmHg of at least 160 캜;
_{(b) -3.0 <pK a <} 1.99; And
(c) reacting in a homogeneous manner, the activity of which is maintained without evaporation of the catalyst.
The method according to claim 1,
(b) -1.0 characterized in that the <pK _a <1.9
The method according to claim 1,
Wherein the catalyst is a naphthalenesulfonic acid.
The method according to claim 1,
Wherein the high-temperature decompression reaction is carried out at a temperature of 130 to 230 DEG C and a pressure of 1 torr to 100 torr.
The method according to claim 1,
Wherein the sugar alcohol is isosorbide and the sugar alcohol is sorbitol.
The method according to claim 1,
Characterized in that the process is carried out in a Continuous Stirred Tank Reactor (CSTR), a Plug Flow Reactor (PFR) or a Batch Reactor (BR).