Preparation method of solid catalyst for polymerization of polypropylene and solid catalyst using the same

1. A method for preparing a solid catalyst for polymerization of polypropylene, comprising:

a) reacting a magnesium halide compound with alcohol and then adding a phthalic acid compound thereto to prepare a magnesium compound solution;

b) mixing an aliphatic or alicyclic hydrocarbon solvent with an aromatic hydrocarbon solvent to prepare a mixed solvent,

dispersing a titanium compound in the mixed solvent,

and then reacting the titanium compound dispersed with the magnesium compound solution prepared in step a), and heating to produce a support; and

c) reacting the support containing the titanium compound used in step b) and an electron donor to obtain a solid product,

wherein the aliphatic or alicyclic hydrocarbon solvent in step b) is mixed at a ratio in a range from 0.2 to 3 moles per mole of the aromatic hydrocarbon solvent.

2. The method of claim 1 , wherein in step a), the magnesium halide compound is reacted with the alcohol in the presence of a hydrocarbon solvent.

3. The method of claim 1 , wherein the phthalic acid compound in step a) is phthalic anhydride or a 1,2-phthaloyl dichloride compound.

4. The method of claim 1 , wherein in step a), the alcohol is reacted at a ratio in a range of from 1 to 10 moles per mole of the magnesium halide compound.

5. The method of claim 2 , wherein the hydrocarbon solvent used in the reaction of the magnesium halide compound and the alcohol is an aliphatic hydrocarbon solvent having 5 or more carbon atoms or an alicyclic hydrocarbon solvent having 5 or more carbon atoms, and is present at a ratio in a range of from 0.2 to 2 moles with respect to the alcohol in step a).

6. The method of claim 1 , wherein the phthalic acid compound in step a) is added at a ratio in a range of from 0.03 to 3 moles per mole of the magnesium halide compound.

7. The method of claim 1 , wherein in step b), the aliphatic or alicyclic hydrocarbon solvent is an aliphatic hydrocarbon solvent having 5 or more carbon atoms or an alicyclic hydrocarbon solvent having 5 or more carbon atoms, and the aromatic hydrocarbon solvent is an aromatic hydrocarbon solvent having 6 or more carbon atoms.

8. The method of claim 1 , wherein the reacting of the mixed solvent in step b) with the magnesium compound solution in step a) is performed under conditions in which the mixed solvent is maintained at a temperature in a range of from −50° C. to 50° C.

9. The method of claim 1 , wherein the support in step c) is reacted with the titanium compound and the electron donor in the presence of a hydrocarbon solvent.

10. The method of claim 1 , wherein in step c), the reacting of the support with the titanium compound and the electron donor is repeated twice or more.

11. The method of claim 1 , wherein the reacting of the support with the titanium compound and the electron donor in step c) includes a process of heating the system to a temperature in a range of from 80° C. to 130° C., aging the system for a period of time in a range of from 1 hr to 3 hrs, and then washing the system.

12. The method of claim 1 , wherein the electron donor in step c) is reacted at a ratio in a range of from 0.01 to 1 mole per mole of the magnesium halide compound.

13. A method for preparing polypropylene comprising:

adding a catalyst prepared by the method of claim 1 , a co-catalyst, an external electron donor and hydrogen to a polymerization reactor; and

introducing propylene to the polymerization reactor followed by polymerization.

14. The method of claim 13 , wherein polypropylene having a bulk density of 0.45 g/ml or more is prepared.

15. The method of claim 13 , wherein in step b), the aliphatic or alicyclic hydrocarbon solvent is an aliphatic hydrocarbon solvent having 5 or more carbon atoms or an alicyclic hydrocarbon solvent having 5 or more carbon atoms, and the aromatic hydrocarbon solvent is an aromatic hydrocarbon solvent having 6 or more carbon atoms.