TWI651338B - Catalyst for esterification reaction and method for catalyzing esterification reaction - Google Patents

Abstract

A catalyst for an esterification reaction and a method for catalyzing the esterification reaction are provided. The catalyst is obtained by reacting a mixture comprising at least one compound containing titanium, zirconium or hafnium, at least one compound containing group IIA element or group IIIA element, and at least one α-hydroxy acid. The catalyst can catalyze the esterification of at least one alcohol with at least one acid.

Description

Catalyst for esterification reaction and catalytic esterification reaction Methods

The invention relates to a catalyst for an esterification reaction and a method for catalyzing the esterification reaction. The invention particularly relates to a catalyst for an esterification reaction, which is obtained by reacting a compound including a compound containing titanium, zirconium or hafnium, a compound containing a group IIA element or a group IIIA element, and an α-hydroxy acid, and Method for catalyzing esterification reaction with this catalyst.

Currently known esterification catalysts include antimony-based, tin-based, and germanium-based catalysts. However, antimony and tin are both potentially toxic metals, limiting the applicability of antimony-based and tin-based catalysts. Especially in polyesters, such as polyethylene terephthalate, the finished product obtained by catalysis with an antimony-based catalyst contains a mixed ester and an antimony-based catalyst. This product is prone to the precipitation of antimony due to the high temperature used in the synthesis, which makes The polyester product has reduced brightness, increased turbidity, and poor quality. In addition, the scarcity of germanium ore sources makes the price of germanium-based catalysts high and difficult to popularize. In addition, the finished product catalyzed by other conventional esterification catalysts has a problem of yellowish color. Therefore, a large amount of toner needs to be added to adjust the finished product's color. As a result, the brightness of the finished product is reduced.

In view of the above, a new catalyst is needed to solve the above problems.

The present disclosure provides a catalyst for an esterification reaction, which is formed by reacting a mixture including at least one first reactant, at least one second reactant, and at least one α-hydroxy acid, wherein the first reactant is The first alkoxide, titanium sulfate, zirconium sulfate, hafnium sulfate, titanium trichloride, titanium tetrachloride, zirconium tetrachloride, or hafnium tetrachloride, and the chemical formula of the first alkoxide is E ₁ (OR ₁ ) ( OR ₂ ) (OR ₃ ) (OR ₄ ), E ₁ is titanium, zirconium or hafnium, R ₁ , R ₂ , R ₃ and R ₄ are independently C ₁ to C ₁₀ alkyl groups; the second reactant is the second Alkoxide, inorganic salt of group IIA element, carboxylate, sulfonate, inorganic salt of group IIIA element, carboxylate or sulfonate, the chemical formula of the second alkoxide is E ₂ (OR ₅ ) (OR ₆ ) (OR ₇ ) _x , E ₂ is a group IIA element or a group IIIA element, R ₅ , R ₆ and R ₇ are independently C ₁ to C ₁₀ alkyl groups, and when E ₂ is a group IIA element, x is 0 When E ₂ is a group IIIA element, x is 1.

In some embodiments, the mixture further includes water.

In some embodiments, the at least one alpha-hydroxy acid includes citric acid, malic acid, maleic acid, lactic acid, tartaric acid, glycolic acid, or a combination thereof.

In some embodiments, based on the weight of the catalyst, the total concentration of titanium, zirconium, and hafnium in the catalyst is 0.1 wt% to 25 wt%.

In some embodiments, based on the weight of the catalyst, the total concentration of Group IIA elements and Group IIIA elements in the catalyst is 0.1wt% ~ 25wt%.

In some embodiments, the ratio between the molar number of at least one α-hydroxy acid and the molar numbers of titanium, zirconium, and hafnium is 1: 1 to 4: 1.

In some embodiments, the group IIA inorganic salt is a group IIA sulfate, nitrate, nitrite, carbonate, phosphate or chloride, and the group IIIA element inorganic salt is a group IIIA element sulfate, nitrate , Nitrite, carbonate, phosphate, or chloride.

The present disclosure provides a method for catalyzing an esterification reaction, comprising subjecting at least one alcohol to at least one acid to an esterification reaction, and adding the aforementioned catalyst for an esterification reaction to form an ester.

In some embodiments, the total concentration of titanium, zirconium, and hafnium is 1 to 500 ppm based on the total weight of the ester and the catalyst.

In some embodiments, based on the total weight of the ester and the catalyst, the total concentration of the group IIA element and the group IIIA element is 1 to 500 ppm.

It should be understood that the foregoing general description and the following detailed description are merely exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

The above and other aspects, features, and other advantages of the present invention can be more clearly understood with reference to the description and the accompanying drawings. Among them: Fig. ^{1 is a 1} H-NMR spectrum (400 MHz, CDCl ₃ ) of the catalyst of Example ¹ . Figure 2 is a ¹ H-NMR spectrum (400 MHz, D ₂ O) of the catalyst of Example ₂ ; Figure 3 is a ¹ H-NMR spectrum (400 MHz, D ₂ O) of the catalyst of Example 3; and FIG. 4 is a ¹ H-NMR spectrum (400 MHz, D ₂ O) of the catalyst of Comparative Example 1. FIG.

In order to make the description of this disclosure more detailed and complete, reference may be made to the accompanying drawings and various embodiments described below. For the sake of clarity, many practical details will be explained in the following description. It should be understood, however, that these practical details should not be used to limit the invention. That is, in some embodiments of the present invention, these practical details are unnecessary.

In this article, unless the article specifically restricts the article, "a" and "the" can refer to a single or multiple. It will be further understood that the terms "including", "including", "having" and similar words used in this document indicate the features, regions, integers, steps, operations, elements and / or components recorded therein, but do not exclude It describes or additionally one or more of its other features, regions, integers, steps, operations, elements, components, and / or groups thereof.

First, the present disclosure provides a catalyst for an esterification reaction. The catalyst is formed by reacting a mixture including at least one first reactant, at least one second reactant, and at least one α-Hydroxy acid. In other words, the catalyst is one or more first reactants, one or more first reactants, The reaction product of two reactants and one or more α-hydroxy acids. The first reactant is a compound containing titanium (Ti), zirconium (Zr), or hafnium (Hf), and the second reactant is a compound containing a Group IIA element or a Group IIIA element. In some embodiments, the molar ratio of the at least one first reactant to the at least one second reactant is 1:10 to 10: 1.

Specifically, the first reactant is a first alkoxide, titanium sulfate, zirconium sulfate, hafnium sulfate, titanium trichloride, titanium tetrachloride, zirconium tetrachloride, or hafnium tetrachloride. The chemical formula of the first alkoxide is E ₁ (OR ₁ ) (OR ₂ ) (OR ₃ ) (OR ₄ ), E ₁ is titanium, zirconium or hafnium, and R ₁ , R ₂ , R ₃ and R ₄ are independently C ₁ ~ C ₁₀ alkyl. In some embodiments, R ₁ , R ₂ , R ₃ and R ₄ are independently a straight-chain alkyl group or a branched-chain alkyl group. For example, R ₁ , R ₂ , R ₃ and R ₄ include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n- Amyl, tert-pentyl, neopentyl, isopentyl, sec-pentyl, 3-pentyl, hexyl, heptyl, octyl, nonyl or decyl.

The second reactant is a second alkoxide, an inorganic salt of a group IIA element (for example, sulfate, nitrate, nitrite, carbonate, phosphate, or chloride of a group IIA element), a carboxylate, or a sulfonic acid Salts, inorganic salts of Group IIIA elements (eg, sulfates, nitrates, nitrites, carbonates, phosphates or chlorides of Group IIIA elements), carboxylates or sulfonates. The chemical formula of the second alkoxide is E ₂ (OR ₅ ) (OR ₆ ) (OR ₇ ) _x . E ₂ is a group IIA element or a group IIIA element. When E ₂ is a group IIA element, x is 0. When E is _{When 2} is a group IIIA element, x is 1. R ₅ , R ₆ and R ₇ are independently C ₁ to C ₁₀ alkyl groups. In some embodiments, R ₅ , R _6, and R ₇ are independently a linear alkyl group or a branched alkyl group. For example, R ₅ , R ₆ and R ₇ include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, Tert-pentyl, neopentyl, isopentyl, sec-pentyl, 3-pentyl, hexyl, heptyl, octyl, nonyl or decyl.

In some embodiments, the at least one alpha-hydroxy acid includes citric acid, malic acid, maleic acid, lactic acid, tartaric acid, glycolic acid, or a combination thereof. In some embodiments, the ratio between the molar number of at least one α-hydroxy acid and the molar numbers of titanium, zirconium, and hafnium is 1: 1 to 4: 1.

In some embodiments, at least one first reactant, at least one second reactant, and at least one alpha-hydroxy acid are reacted at a temperature of about 70 ° C to about 100 ° C to form a catalyst. In some embodiments, at least one first reactant, at least one second reactant, and at least one α-hydroxy acid are added to a polar solvent (for example, water) to perform a reaction to form a catalyst. In some embodiments, based on the weight of the catalyst, the total concentration of titanium, zirconium, and hafnium in the catalyst is 0.1 wt% to 25 wt%. In some embodiments, based on the weight of the catalyst, the total concentration of Group IIA elements and Group IIIA elements in the catalyst is 0.1 wt% to 25 wt%.

During the reaction between the first reactant, the second reactant, and the α-hydroxy acid, the group next to titanium, zirconium, hafnium, a group IIA element, or a group IIIA element (for example: (Alkoxy, sulfate, nitrate, nitrite, carbonate, phosphate, chloride, carboxylate, or sulfonate) may be removed, so that the α-hydroxy acid may remove hydrogen from the carboxyl group (- H), and then connected to titanium, zirconium, hafnium, group IIA element or group IIIA element. For example, if the first reactant is a titanium alkoxide and the second reactant is an aluminoxide, α -Hydroxy acid is citric acid. During the reaction of titanyl oxide and aluminoalkoxide with citric acid, the alkoxy group on the alkoxide will be replaced by the ligand formed by citric acid, and citric acid will be formed. A compound in which the formed ligand is linked to "titanium" or "aluminum". The alkoxy group on the titanium alkoxide or aluminoalkoxide may be partially or completely substituted by a ligand. Because citric acid has three carboxylic acid groups, citric acid has the ability to react with three alkoxides. Therefore, citric acid has the ability to react with different alkoxides, and may form a compound in which a ligand formed by citric acid is simultaneously connected to "titanium" and "aluminum".

In some embodiments, the mixture comprising at least one first reactant, at least one second reactant, and at least one alpha-hydroxy acid further comprises water. Therefore, the catalyst is formed by reacting a mixture including at least one first reactant, at least one second reactant, and at least one alpha-hydroxy acid with water. In other words, the catalyst is the product of the reaction of one or more first reactants, one or more second reactants, one or more alpha-hydroxy acids, and water.

In some embodiments, the first or second reactant is a metal alkoxide. The metal alkoxide may react with water, so that the alkoxy group of the metal alkoxide is substituted with a hydroxyl group (-OH). Two molecules with a metal-OH structure may react, removing water to form larger molecules. This reaction is called a condensation reaction. Therefore, if the above-mentioned condensation reaction continuously occurs, the mixture of metal alkoxide and water may include a polymer formed by the reaction of metal alkoxide and water. Therefore, when the catalyst is formed by the reaction of metal alkoxide, α-hydroxy acid and water, the catalyst will include the product of the reaction of the above polymer with α-hydroxy acid.

Next, the present disclosure provides a method for catalyzing an esterification reaction, including the following steps: at least one alcohol and at least one acid are subjected to an esterification reaction, and the catalyst for an esterification reaction according to any one of the preceding embodiments is added. The finished product is a mixture including a catalyst and an ester. In some embodiments, the total concentration of titanium, zirconium, and hafnium is 1 to 500 ppm based on the total weight of the mixture. In some embodiments, based on the total weight of the mixture, the total concentration of Group IIA elements and Group IIIA elements is 1 to 500 ppm.

In some embodiments, at least one alcohol includes a unit alcohol, a polyol, or a combination thereof. In some embodiments, the alcohol is a polyhydric alcohol, and at least one alcohol includes, but is not limited to, ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, isosorbide, pentaerythritol, or a combination thereof.

In some embodiments, the at least one acid includes a monoacid, a polyacid, or a combination thereof. In some embodiments, the acid is a polyacid. In some embodiments, the polyacid is a polycarboxylic acid. In some embodiments, the at least one acid includes, but is not limited to, phthalic acid, isophthalic acid, terephthalic acid, phthalic acid, m-naphthalic acid, p-naphthalic acid, citric acid, 2,5- Furandicarboxylic acid, adipic acid, or a combination thereof.

In some embodiments, the alcohol is a polyhydric alcohol and the acid is a polybasic acid. Therefore, the method of catalyzing the esterification reaction can also be referred to as the method of catalyzing the polyester reaction.

The following embodiments are used to describe specific aspects of the present invention, and to enable those having ordinary knowledge in the technical field to which the present invention pertains to implement the present invention. The following examples should not be used to limit the invention.

Experimental Example 1: Synthesis catalyst

The experimental procedure of Comparative Example 1 is as follows. A solution of citric acid monohydrate (176.9 g, 0.84 mole) and water (210.1 g) is prepared in a four-neck round bottom flask of 1 liter capacity equipped with a stirrer, a condenser tube and a thermometer. Using an addition funnel, slowly add isopropyl titanate (95.4g, 0.34mole) to a four-necked round-bottomed flask, heat it to about 70 ° C to 100 ° C and reflux for 1 hour, and then distill the isopropanol through vacuum distillation. Propanol and water were distilled off. Finally, a catalyst with a titanium content of 5 wt% was obtained, which was a light yellow solution.

By using the above steps, the catalysts of Examples 1 to 3 can be prepared. The difference between Examples 1 to 3 and Comparative Example 1 is that the types of alkoxides in the reactants are different. Comparative Example 1 uses only a single type of alkoxide as the reactant, and Examples 1 to 3 use two types of alkoxide as the reactant. The reactants used to prepare the catalysts of Examples 1 to 3 and Comparative Example 1 are shown in Table 1 below.

Next, the catalysts of Examples 1 to 3 and Comparative Example 1 were analyzed by nuclear magnetic resonance method. Please refer to Figs. 1 to 4. Fig. 1 is a ¹ H-NMR spectrum (400 MHz, CDCl ₃ ) of the catalyst of Example ^1; Fig. 2 is a ¹ H-NMR spectrum (400 MHz, of the catalyst of Example 2) D ₂ O); FIG. 3 is a ¹ H-NMR spectrum of the catalyst of Example 3 (400 MHz, D ₂ O); FIG. 4 is a ¹ H-NMR spectrum of the catalyst of Comparative Example ¹ (400 MHz, D ₂ O).

In Figure 4, the signal at a chemical shift of about 2.4 ppm to 2.8 ppm is a signal of hydrogen on a ligand formed by citric acid connected to "titanium". In the first figure, the signal at a chemical shift of about 2.4 ppm to 2.8 ppm is a signal of hydrogen on a ligand formed by citric acid. Comparing Fig. 1 and Fig. 4, it can be seen that the signal strength and position of Fig. 1 are different from those of Fig. 4, which proves that the catalyst of Example 1 includes a ligand formed by citric acid at the same time. Compounds linked to "titanium" and "aluminum".

Therefore, comparing Figures 2 to 3 and Figure 4 respectively, it can also be seen that the catalyst of Example 2 includes a compound formed by citric acid with a ligand that is simultaneously connected to "titanium" and "boron"; The catalyst of Example 3 includes a compound in which a ligand formed from citric acid is simultaneously connected to "titanium" and "magnesium".

Experimental Example 2: Catalyzed Polyester Reaction with Catalyst

In this experimental example, the catalysts of Examples 1 to 3 and Comparative Examples 1 to 2 were used to catalyze the esterification of ethylene glycol (Ethylene Glycol, EG) with terephthalic acid (TPA) to form a polymer. 1. ethylene terephthalate PET). The catalyst of Comparative Example 2 was antimony acetate (Antimony (III) acetate). The process of forming PET can be divided into three stages: (1) pre-esterification, (2) poly-condensation (PC), and (3) solid state polymerization (SSP).

First, (1) pre-esterification, mixing EG and TPA (molar ratio of 1.25: 1), and then heating the mixture in a closed reactor to about 230 ° C to 270 ° C, and pre-esterification of EG and TPA. Next, a catalyst and phosphoric acid are added to obtain a mixture including pre-esterified EG and TPA, a catalyst, and phosphoric acid. The element concentration and phosphorus concentration of the catalyst in the mixture are shown in Table 2 below.

Subsequently, the pre-esterified EG was subjected to (2) PC reaction with TPA by heating to about 270 ° C to 290 ° C under vacuum, and stirring was performed with a stirrer during the reaction. After the torque value of the agitator reaches a set value (240 / kW), the temperature is lowered and the vacuum is released, the material is discharged and the obtained product is cut into ester particles. Please refer to Table 2 below for the time required for the PC reaction, the acid value, melting point (T _m ) and intrinsic viscosity of the ester particles, and the L value, a value, and b value of the ester particles. The L value represents the brightness of the ester particles, and the larger the number, the brighter it is. The positive value of a indicates that the ester particles are reddish, the larger the number represents the redder; the negative value of a indicates that the ester particles are greener, and the larger the number represents greener. A positive b value indicates that the ester particles are yellowish, a larger number indicates a yellower color; a negative b value indicates that the ester particles are blue, and a larger number indicates a bluer color.

Next, (3) SSP is performed, and the ester particles are evacuated in a solidification reaction kettle and heated to about 220 ° C for 24 hours, and then the temperature is lowered. See Table 3 below for the intrinsic viscosity of the ester particles obtained after SSP. In addition, Table 3 also lists the intrinsic viscosity difference, which is the intrinsic viscosity value of the ester particles after SSP minus the intrinsic viscosity value of PC.

In general, the more high molecular weight compounds contained in a material, the greater the intrinsic viscosity. From the characteristic viscosity of the ester particles after SSP in Table III In view of the degree values, the catalysts of Examples 1 to 3 can effectively catalyze the esterification reaction, and the effect is better than or similar to the catalysts of Comparative Examples 1 to 2. It is worth noting that the catalysts of Examples 1 to 3 only need to add a small amount to have a catalytic effect better than or similar to that of the catalyst of Comparative Example 2.

In addition, the catalytic effect of the catalyst can be seen from the intrinsic viscosity difference in Table III. The catalysts of Examples 1 to 2 can effectively increase the rate of SSP, and the effect is better than that of Comparative Example 1. In addition, the catalysts of Examples 1 to 3 only need to add a small amount to have a catalytic effect similar to that of the catalyst of Comparative Example 2.

In addition, from the values of L, a, and b listed in Table 2, the SSP ester particles obtained from the catalysts of Examples 1 to 3 have good brightness and chromaticity.

In summary, the present disclosure provides a catalyst for an esterification reaction that is capable of effectively catalyzing the esterification reaction. In addition, the catalyst does not contain any potentially toxic metals (such as antimony, tin), and is a relatively environmentally friendly catalyst. In addition, the finished product (ester particles) obtained by using this catalyst to catalyze the esterification reaction can have good brightness and chromaticity. In addition, the present disclosure can use a titanium-containing compound as a reactant to synthesize a catalyst. One of the advantages of using a titanium-containing compound is that titanium is an element with abundant reserves on the earth and can be easily obtained. Based on the above, the catalysts of this disclosure not only have industrial applicability and commercial potential, but also have the ability to replace existing esterification catalysts (such as antimony-based, tin-based, and germanium-based catalysts).

Although the present invention has been disclosed as above by way of implementation, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any familiarity Those skilled in the art, without departing from the spirit and scope of the present invention, should be able to make various equal changes and modifications, all of which shall fall within the scope of the present invention. Therefore, the scope of protection of the present invention shall be defined by the scope of the attached patent application. Whichever comes first.

Claims (7)

A catalyst for esterification reaction is formed by reacting a mixture including at least one first reactant, at least one second reactant, and at least one α-hydroxy acid, wherein the first reactant is a first alkane Oxide, titanium sulfate, zirconium sulfate, hafnium sulfate, titanium trichloride, titanium tetrachloride, zirconium tetrachloride or hafnium tetrachloride. The chemical formula of the first alkoxide is E ₁ (OR ₁ ) (OR ₂ ) (OR ₃ ) (OR ₄ ), E ₁ is titanium, zirconium or hafnium, R ₁ , R ₂ , R ₃ and R ₄ are independently C ₁ to C ₁₀ alkyl groups; the second reactant is a second alkane Oxide, inorganic salt of group IIA element, carboxylate, sulfonate, inorganic salt of group IIIA element, carboxylate or sulfonate, the chemical formula of the second alkoxide is E ₂ (OR ₅ ) (OR ₆ ) (OR ₇ ) _x , E ₂ is a group IIA element or a group IIIA element, R ₅ , R ₆ and R ₇ are independently C ₁ to C ₁₀ alkyl groups, and when E ₂ is a group IIA element, x is 0 When E ₂ is a group IIIA element, x is 1, wherein the total concentration of titanium, zirconium, and hafnium in the catalyst is 0.1% to 25% by weight based on the weight of the catalyst. The group IIA element and the The total concentration of group IIIA elements is 0.1 wt% to 25 wt%, and the at least The ratio between the number of moles of the respective molar number of titanium, zirconium or hafnium α- hydroxy acid is 1: 1 to 4: 1. The catalyst of claim 1, wherein the mixture further comprises water. The catalyst according to claim 1, wherein the at least one alpha-hydroxy acid comprises citric acid, malic acid, maleic acid, lactic acid, tartaric acid, glycolic acid, or a combination thereof. The catalyst according to claim 1, wherein the inorganic salt of group IIA is a sulfate, nitrate, nitrite, carbonate, phosphate or chloride of group IIA, and the inorganic salt of group IIIA element is IIIA Sulfates, nitrates, nitrites, carbonates, phosphates or chlorides of the group elements. A method for catalyzing an esterification reaction, comprising: subjecting at least one alcohol to at least one acid to an esterification reaction, and adding the catalyst according to claim 1 to form an ester. The method according to claim 5, wherein the total concentration of titanium, zirconium and hafnium is 1 to 500 ppm based on the total weight of the ester and the catalyst. The method according to claim 5, wherein the total concentration of the group IIA element and the group IIIA element is 1 to 500 ppm based on the total weight of the ester and the catalyst.