Organic zinc catalyst and preparation method thereof

Abstract

An organic zinc catalyst and a preparation method thereof are provided. According to the present invention, the organic zinc catalyst has a smaller thickness and a larger surface area to exhibit more improved activity in polymerization for the preparation of a poly(alkylene carbonate) resin.

Claims

1. A method of preparing an organic zinc catalyst, the method comprising: reacting a zinc precursor and dicarboxylic acid having 3 to 20 carbon atoms to form zinc dicarboxylate-based particles in a liquid medium containing a polar solvent and a non-polar solvent at a volume ratio of 30:70 to 75:25, wherein the zinc dicarboxylate-based particles formed by the reaction have an average particle thickness of 30 nm or less and an argon adsorption Brunauer-Emmett-Teller (BET) surface area of 20 m.sup.2/g or more.

2. The method of claim 1, wherein the polar solvent is a solvent having a dielectric constant of 20 or more at 25° C. or lower, and the non-polar solvent is a solvent having a dielectric constant of less than 15 at 25° C. or lower.

3. The method of claim 1, wherein the polar solvent is one or more compounds selected from the group consisting of methanol, ethanol, acetic acid, acetone, N,N-dimethylformamide, N,N-dimethylacetamide, propylene carbonate, acetonitrile, dimethyl sulfoxide, and hexamethylphosphotriamide.

4. The method of claim 1, wherein the non-polar solvent is one or more compounds selected from the group consisting of toluene, benzene, xylene, diethylether, tetrahydrofuran, 1,4-dioxane, dimethylcarbonate, and diethylcarbonate.

5. The method of claim 1, wherein the zinc precursor is one or more compounds selected from the group consisting of zinc oxide, zinc sulfoxide (ZnSO.sub.4), zinc chlorate (Zn(ClO.sub.3).sub.2), zinc nitrate (Zn(NO.sub.3).sub.2), zinc acetate (Zn(OAc).sub.2), and zinc hydroxide.

6. The method of claim 1, wherein the dicarboxylic acid having 3 to 20 carbon atoms is one or more compounds selected from the group consisting of malonic acid, glutaric acid, succinic acid, adipic acid, terephthalic acid, isophthalic acid, homophthalic acid, and phenylglutaric acid.

7. The method of claim 1, wherein the dicarboxylic acid is used in an amount of about 1 to 1.5 mol, based on 1 mol of the zinc precursor.

8. The method of claim 1, wherein the reaction is performed at a temperature of about 20 to 110° C. for 1 to 20 h.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a scanning electron microscopic image of an organic zinc catalyst according to a comparative example of the present invention; and

(2) FIG. 2 is a scanning electron microscopic image of an organic zinc catalyst according to an example of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(3) Hereinafter, the preferred examples are provided for better understanding. However, these examples are for illustrative purposes only, and the invention is not intended to be limited by these examples.

Example 1

(4) 75 ml of a solvent containing ethanol and toluene at a volume ratio of 50:50, 50 mmol of ZnO, and 50 mmol of glutaric acid were added to a 250 mL-round bottom flask at room temperature, the temperature thereof was raised to 60° C., and they were allowed to react under vigorous agitation for 10 h. Thereafter, the reaction vessel was cooled to room temperature, and precipitates were separated by filtration. The precipitates thus separated were washed with acetone three times or more. The precipitates thus washed were dried in a vacuum oven at 85° C. for 12 h, and finally, 9.5 g of zinc glutarate particles was obtained in a yield of about 97%.

Example 2

(5) 9.3 g of zinc glutarate particles was prepared in a yield of about 95% in the same manner as in Example 1, except that 75 ml of a solvent containing ethanol and toluene at a volume ratio of 75:25 was used.

Example 3

(6) 9.3 g of zinc glutarate particles was prepared in a yield of about 95% in the same manner as in Example 1, except that 75 ml of a solvent containing ethanol and toluene at a volume ratio of 30:70 was used.

Comparative Example 1

(7) 9.5 g of zinc glutarate particles was prepared in a yield of about 97% in the same manner as in Example 1, except that 75 ml of toluene was used as a solvent.

Comparative Example 2

(8) 9.3 g of zinc glutarate particles was prepared in a yield of about 95% in the same manner as in Example 1, except that 75 ml of a solvent containing ethanol and toluene at a volume ratio of 25:75 was used.

Comparative Example 3

(9) 9.3 g of zinc glutarate particles was prepared in a yield of about 95% in the same manner as in Example 1, except that 75 ml of a solvent containing ethanol and toluene at a volume ratio of 80:20 was used.

Experimental Example 1

(10) Zinc glutarate particles were dried under vacuum at 200° C. for 3 h, argon adsorption Brunauer-Emmett-Teller (BET) surface area was measured using an instrument for measuring a particle surface area, and the results are given in the following Table 1.

Experimental Example 2

(11) An average particle size (D50) of the zinc glutarate particle and average thickness of the side of the particles were measured and the results are given in the following Table 1.

(12) In this regard, the average particle size was measured by PSA (particle size analysis) using MASTERSIZER 3000 manufactured by Malvern.

(13) The average particle thickness was measured by SEM image analysis of particles having a length and width in the range of about 100 to 500 nm for convenience of the thickness measurement. An SEM image of Comparative Example 1 is shown in FIG. 1, and an SEM image of Example 1 is shown in FIG. 2.

Experimental Example 3

(14) Zinc glutarate obtained in the example or comparative example was used as a catalyst to polymerize and prepare a polyethylene carbonate by the following method. First, in a glove box, 0.2 g of the catalyst and 8.52 g of dichloromethane (methylene chloride) were added to a high-pressure reactor, and 8.9 g of ethylene oxide was added thereto. Thereafter, the reactor was pressurized to 30 bar using carbon dioxide. Polymerization was performed at 70° C. for 3 h. After completing the polymerization, unreacted carbon dioxide and ethylene oxide were removed, together with the solvent, dichloromethane. In order to quantify polyethylene carbonate thus prepared, the remaining solids were completely dried and quantified. The catalytic activities according to the polymerization results are given in the following Table 1.

(15) TABLE-US-00001 TABLE 1 BET Average surface Average particle Catalytic activity area particle size thickness (g-polymer/ (m.sup.2/g) (nm) (nm) g-catalyst) Example 1 41.2 660 20 42 Example 2 38.2 800 21 36 Example 3 22.5 670 29 35 Comparative 11.9 530 62 23 Example 1 Comparative 15.1 700 50 30 Example 2 Comparative 17.2 740 45 26 Example 3

(16) Referring to Table 1, zinc glutarates according to the comparative examples were found to have a BET surface area of less than 20 m.sup.2/g and an average particle thickness of more than 40 nm. In contrast, zinc glutarates according to the examples were found to have a large BET surface area of 20 m.sup.2/g or more and a low average particle thickness of 30 nm or less, and to have higher catalytic activity.