Mesoporous silica/ceria-silica composite and method for preparing same
The present invention relates to a mesoporous silica/ceria-silica composite and a method for preparing a mesoporous composite and, more specifically, to a mesoporous silica/ceria-silica composite which is composed of mesoporous silica having a hexagonal or cubic structure and ceria having a hexagonal structure provided on a surface and pores of the mesoporous silica, the oxidation state of the ceria being Ce 4+ and Ce 3+ .
1. A mesoporous silica/ceria-silica composite comprising a mesoporous silica having a hexagonal structure or a cubic structure and a ceria having the hexagonal structure and provided on a surface and in a pore of the mesoporous silica, wherein oxidation states of the ceria are Ce 4+ and Ce 3+ ,
wherein, in the oxidation states of the ceria, the Ce 3+ has a content of 10.2 mole % to 23.8 mole % based on a total cerium, and the Ce 4+ has a content of 76.2 mole % to 89.8 mole % based on the total cerium.
2. The mesoporous silica/ceria-silica composite of claim 1 , wherein a mole ratio of Ce of the ceria to Si of the silica is in a range of 0.001 to 0.5.
3. The mesoporous silica/ceria-silica composite of claim 1 , wherein the mesoporous silica has a pore volume of 0.20 cm 3 /g to 0.40 cm 3 /g.
4. The mesoporous silica/ceria-silica composite of claim 1 , wherein the mesoporous silica/ceria-silica composite has a BET specific surface area of 250 m 2 /g to 600 m 2 /g.
5. A method of preparing a mesoporous silica/ceria-silica composite, the method comprising:
mixing and stirring a cationic surfactant, a silica precursor, and a cerium precursor;
preparing the mesoporous silica/ceria-silica composite by calcining a mixed solution after performing a hydrothermal reaction for the mixed solution; and
reducing the prepared mesoporous silica/ceria-silica composite,
wherein the reducing is performed at a temperature of 850° C. to 900° C. for 3 hours to 6 hours,
wherein a structure of mesoporous silica/ceria-silica composite is stable while the reducing is performed.
6. The method of claim 5 , wherein the cationic surfactant includes hexadecyl trimethyl ammonium bromide (CTAB) or hexadecyl trimethyl ammonium chloride (CTACl).
7. The method of claim 5 , wherein the silica precursor includes tetraethyl orthosilicate (TEOS) or tetramethyl orthosilicate (TMOS).
8. The method of claim 5 , wherein the cerium precursor includes one selected from the group consisting of cerium hydroxide (Ce(OH) 4 ), cerium nitrate (Ce(NO 3 ) 3 ), and cerium sulfate (Ce 2 (SO 4 ) 3 , Ce(SO 4 ) 2 ).
9. The method of claim 5 , wherein a mole ratio of the cerium precursor to the silica precursor is in a range of 0.001 to 0.5.
10. The method of claim 5 , wherein the stirring is performed at a rate of 200 rpm to 600 rpm for 30 min. to 1440 min.
11. The method of claim 5 , wherein the hydrothermal reaction is performed at a temperature of 80° C. to 120° C. for 20 hours to 48 hours.
12. The method of claim 5 , wherein the calcining is performed under air at a temperature of 500° C. to 600° C. for 4 hours to 6 hours.
13. A mesoporous silica/ceria-silica composite comprising a mesoporous silica having a hexagonal structure or a cubic structure and a ceria having the hexagonal structure and provided on a surface and in a pore of the mesoporous silica,
wherein the ceria is reduced through heat treatment and the ceria is present in oxidation states of Ce 3+ , and
wherein the ceria has diffraction patterns which are matched with that of Ce 4.667 Si 3 O 13 in a structure similar to an apatite structure having a hexagonal unit lattice.
14. The mesoporous silica/ceria-silica composite of claim 13 , wherein the Ce 3+ has a content of 10.2 to 100 mole % based on a total cerium.