Method for preparing 1,3-cyclohexanedicarboxylic acid

Abstract

The present invention relates to a method for preparing 1,3-cyclohexanedicarboxylic acid capable of exhibiting excellent activity, of enhancing the reaction efficiency and economic efficiency by using a catalyst having improved durability under the reaction conditions of high temperature and strong acid, of achieving excellent conversion rates by allowing most of reactants to participate in the reaction, and of obtaining products having high purity while minimizing by-products within a shorter period of time. The method for preparing 1,3-cyclohexanedicarboxylic acid may include: reducing isophthalic acid in the presence of a metal catalyst fixed to a silica support and containing a palladium (Pd) compound and a copper (Cu) compound in a weight ratio of 1:0.1 to 0.5.

Claims

1. A method for preparing 1,3-cyclohexanedicarboxylic acid comprising: reducing isophthalic acid in the presence of a metal catalyst fixed to a silica support and containing a palladium (Pd) compound and a copper (Cu) compound in a weight ratio of 1:0.1 to 0.5.

2. The method for preparing 1,3-cyclohexanedicarboxylic acid of claim 1, wherein the silica support contained in the metal catalyst has a specific surface area of 100 m.sup.2/g to 500 m.sup.2/g.

3. The method for preparing 1,3-cyclohexanedicarboxylic acid of claim 1, wherein the total pore volume of the silica support contained in the metal catalyst is be 0.5 cm.sup.3/g to 2 cm.sup.3/g.

4. The method for preparing 1,3-cyclohexanedicarboxylic acid of claim 1, wherein the average pore diameter of the silica support contained in the metal catalyst is 80 to 200 .

5. The method for preparing 1,3-cyclohexanedicarboxylic acid of claim 1, wherein the metal catalyst includes 0.1% to 10% by weight of the palladium (Pd) compound relative to the silica support.

6. The method for preparing 1,3-cyclohexanedicarboxylic acid of claim 1, wherein the step of reducing isophthalic acid includes contacting the isophthalic acid with hydrogen gas.

7. The method for preparing 1,3-cyclohexanedicarboxylic acid of claim 1, wherein the step of reducing isophthalic acid is carried out at 50 C. to 350 C.

8. The method for preparing 1,3-cyclohexanedicarboxylic acid of claim 1, wherein the step of reducing isophthalic acid is carried out under a pressure of 30 bar to 150 bar.

9. The method for preparing 1,3-cyclohexanedicarboxylic acid of claim 1, wherein the metal catalyst is used in an amount of 10 to 80 parts by weight relative to 100 parts by weight of the isophthalic acid.

10. The method for preparing 1,3-cyclohexanedicarboxylic acid of claim 1, wherein the metal catalyst includes a palladium (Pd) compound and a copper (Cu) compound in a weight ratio of 1:0.3 to 0.5.

11. The method for preparing 1,3-cyclohexanedicarboxylic acid of claim 1, wherein a selectivity defined by the following Equation 1 is 90% or more:
Selectivity (%)=[(Amount of 1,3-cyclohexanedicarboxylic acid (mol %)/Amount (mol %) of product)*100].[Equation 1]

12. The method for preparing 1,3-cyclohexanedicarboxylic acid of claim 1, wherein after a step of reducing isophthalic acid in the presence of a metal catalyst fixed to a silica support and containing a palladium (Pd) compound and a copper (Cu) compound in a weight ratio of 1:0.1 to 0.5, the method further comprises a step of recovering the metal catalyst; and a step of reducing the isophthalic acid in the presence of the recovered metal catalyst.

13. The method for preparing 1,3-cyclohexanedicarboxylic acid of claim 12, wherein the step of recovering the metal catalyst; and the step of reducing the isophthalic acid in the presence of the recovered metal catalyst are repeatedly carried out twice or more.

14. The method for preparing 1,3-cyclohexanedicarboxylic acid of claim 12, wherein in the step of reducing the isophthalic acid in the presence of the recovered metal catalyst, the conversion rate defined by the following Equation 2 is 45% or more:
Conversion rate (%)=[(Amount of 1,3-cyclohexanedicarboxylic acid added (mol %))(Amount of 1,3-cyclohexanedicarboxylic acid remaining after reaction (mol %))]/[Amount of 1,3-cyclohexanedicarboxylic acid added (mol %)]*100.[Equation 2]

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

(1) The present invention will be described in more detail by way of Examples shown below. However, these Examples are given for illustrative purposes only, and the scope of the invention is not intended to be limited to or by these Examples.

Preparation Examples 1 to 3: Preparation of Metal Catalyst

Preparation Example 1

(2) Palladium(II) nitrate dihydrate (Pd(NO.sub.3).sub.2.2H.sub.2O) and copper nitrate trihydrate (CuNO.sub.3.3H.sub.2O) were dissolved in ion-exchanged water to prepare a metal precursor solution. The metal precursor solution was dropped by the inner pore volume of the silica support [specific surface area: about 255 m.sup.2/g, total pore volume: 1.03 cm.sup.3/g, average pore diameter: 110 ] to support the catalyst, which was then dried at 110 C. for 24 hours. Thereafter, the catalyst was calcined at 500 C. under an air condition to obtain a catalyst in which palladium and copper were supported in the form of a composite metal. (The weight ratio of palladium (Pd) and copper (Cu) is as shown in Table 1 below).

Preparation Example 2

(3) A metal catalyst was prepared in the same manner as in Preparation Example 1, except that the weight ratio of palladium (Pd) and copper (Cu) was changed as shown in Table 1 below.

Preparation Example 3

(4) A metal catalyst was prepared in the same manner as in Preparation Example 1, except that the weight ratio of palladium (Pd) and copper (Cu) was changed as shown in Table 1 below.

Examples 1 to 3: Preparation of 1,3-Cyclohexanedicarboxylic Acid

Example 1

(5) The metal-supported catalyst obtained in Preparation Example 1, isophthalic acid, and ion-exchange water were charged into a 500 ml high-pressure reactor equipped with a stirrer so as to satisfy the weight ratios shown in Table 1 below. After replacing the atmosphere in the high-pressure reactor with nitrogen at room temperature, the temperature inside the high-pressure reactor was raised to 230 C. while introducing hydrogen gas into the high-pressure reactor, thereby carrying out hydrogenation reaction under a pressure of 80 bar. At this time, the stirring speed in the high-pressure reactor was fixed to 350 rpm and the reaction was carried out for 80 minutes. When the reaction time was reached, the inside of the reactor was cooled to room temperature, and filtered to collect a reaction product. Water was removed from the collected reaction product by distillation using a rotary evaporator to obtain 1,3-cyclohexanedicarboxylic acid as a final product.

Example 2

(6) 1,3-cyclohexanedicarboxylic acid was prepared in the same manner as in Example 1, except that 15 wt % of isophthalic acid was used as shown in Table 1 below.

Example 3

(7) The metal catalyst used in Example 2 was filtered and then reused to prepare 1,3-cyclohexanedicarboxylic acid in the same manner as in Example 2. Subsequently, the same procedure was repeated.

Comparative Examples 1 to 4: Preparation of 1,3-Cyclohexanedicarboxylic Acid

Comparative Example 1

(8) 1,3-cyclohexanedicarboxylic acid was prepared in the same manner as in Example 1, except that the metal-supported catalyst obtained in Preparation Example 2 was charged.

Comparative Example 2

(9) 1,3-cyclohexanedicarboxylic acid was prepared in the same manner as in Example 1, except that the metal-supported catalyst obtained in Preparation Example 3 was used.

Comparative Example 3

(10) 1,3-cyclohexanedicarboxylic acid was prepared in the same manner as in Example 2, except that the metal-supported catalyst obtained in Preparation Example 2 was used.

Comparative Example 4

(11) The metal catalyst used in Comparative Example 3 was filtered and then reused to prepare 1,3-cyclohexanedicarboxylic acid in the same manner as in Comparative Example 3. Subsequently, the same procedure was repeated.

Experimental Example: Measurement of Physical Properties of 1,3-Cyclohexanedicarboxylic Acid Obtained in Examples and Comparative Examples

(12) The physical properties of 1,3-cyclohexanedicarboxylic acid obtained in the above Examples and Comparative Examples were measured by the following methods, and the results are shown in Table 1 below.

Experimental Example 1: Conversion Rate and Selectivity

(13) The conversion rate of the reactant (isophthalic acid) and the selectivity of 1,3-cyclohexanedicarboxylic acid were measured for the final products obtained in the Examples and Comparative Examples using gas chromatography (GC).

(14) Specifically, the reaction product obtained by the reduction reaction (hydrogenation) of the reactant (isophthalic acid) was diluted with methanol. The diluted solution was analyzed by gas chromatography (GC) to determine the selectivity and conversion rate according to the following Equation. In Equation, each numerical value was converted to a unit of molar ratio (%) and applied.
Selectivity (%)=[(Amount of 1,3-cyclohexanedicarboxylic acid (mol %)/Amount of product(mol %))*100]
Conversion rate (%)=[(Amount of 1,3-cyclohexanedicarboxylic acid added (mol %))(Amount of 1,3-cyclohexanedicarboxylic acid remaining after reaction (mol %))]/[Amount of 1,3-cyclohexanedicarboxylic acid added (mol %)]*100.
Gas Chromatography (GC) Conditions

(15) 1) Column: Agilent 19091J-413 (column length: 30 m, internal diameter: 0.32 mm, film thickness: 0.25 m)

(16) 2) GC system: Gas Chromatography Model Agilent 7890

(17) 3) Carrier Gas: Helium

(18) 4) Detector: Flame Ionization Detector (FID)

(19) TABLE-US-00001 TABLE 1 Results of Experimental Example of Examples and Comparative Examples Reactants (wt % in reaction Catalyst system) Pd/Cu (wt % (wt % in isophthalic in supported reaction Conversion Selectivity Category acid catalyst) Support system) rate (%) (%) Example 1 5 1/0.2 silica 2 92.7 93.7 Example 2 15 1/0.2 silica 2 55.7 94.1 Example 3 15 silica 2 1 time-50.2 1 time- 2 times- 93.4 48.3 2 times- 3 times- 92.2 48.8 3 times- 87.1 Comparative 5 1/0 silica 2 98.4 97.1 Example 1 Comparative 5 1/0.6 silica 2 61.7 94.5 Example 2 Comparative 15 1/0 silica 2 60.6 94.5 Example 3 Comparative 15 silica 2 1 time-60.1 1 time- Example 4 2 times- 92.4 59.6 2 times- 3 times- 90.9 41.4 3 times- 92.1

(20) From the results in Table 1, it can be seen that the palladium-copper composite metal catalyst of Example 1, had equivalent levels of conversion rate and selectivity as compared with the palladium catalysts of Comparative Examples 1 and 2.

(21) However, it can be confirmed that in Examples 2 and 3 in which catalyst deactivation was accelerated, the initial conversion rate was 55.7%, and while repeating 3 times, the lowest conversion rate was 48.3% and the extent of decrease of the conversion rate was about 7%, whereas in the case of Comparative Examples 3 and 4 using the palladium catalyst, the initial conversion was 60.6%%, and while repeating 3 times, the lowest conversion rate was 41.4% and the extent of decrease of the conversion rate increased rapidly to about 20%,

(22) That is, it can be confirmed that when the palladium-copper composite metal catalysts of Examples were used, even during repetitive reactions under non-accelerated conditions, rapid reduction of reaction conversion rate can be prevented due to maintenance of activity due to improvement of acid resistance of the catalyst.