Chang, Juyeon and Jung, Duk-Young*Synthesis and Characterization of Mesostructured Vanadium OxideDepartment of Chemistry-BK21, SungKyunKwan University, Suwon 440-746, Korea

Introduction : Mesoporous Materials2. Synthesis of Vanadate/Surfactant Clusters.3. Hydrothermal reaction of Vanadate/Surfactant Clusters. : 1) As temperature is varied 2) As pH is variedEffect on UV/O3 Treatment :As time is varied5. Conclusion

Based on Surfactant-Assisted OrderingC. T. Kresge et al., Nature, 1992, 359, 710.silicatecalcinationMCM-41

Solution 51V NMR spectra of vanadate solutions with various pH. Predominance diagram for V(V)-OH- species V. Luca et al., Chem. Mater. 1992, 9, 2731.135

1. VOxn- (pH, conc. control) : 0.15M NaVO3 solution(pH8.2(1), 6.7(3) and 5.0(5)) with addition of 2M HCl soln.

2. VOxn- + C16TMA-Bromide : Addition of excess CH3(CH2)15N(CH3)3Br soln.(wt 2.7%) to vanadate soln

3. The colored precipitates are obtained. : C16TMA-V1(white, pH8.4), C16TAM-V3(pale- yellow, pH6.5) and C16TMA-V5(orange, pH4.8) filtered, washing with double distilled water.

- C16TMA-Bromide (cetyltrimethylammonium bromide ) -

VO3 stretchingV-O-V banding (tetrahedral)V-O-V banding(octaherdal)Powder XRD PatternsFT-IR spectra

A. Monnier et al., Science. 1993, 261, 1299.Hydrothermal Reaction

Hydrothermal Reaction at Various Temperatures. : Starting material : C16TMA-V1, C16TA-V3 and C16TMA-V5. Solvent : double distilled water. Temperature : 403K, 433K, and 463KHydrothermal Reaction after pH control. : Starting material : C16TMA-V1, C16TA-V3 and C16TMA-V5. Solvent : double distilled water. Temperature : 433K

Powder XRD Patterns for C16TMA-V1Powder XRD Patterns for C16TMA-V5L : lamellar, H : hexagonal structure

Powder XRD Patterns for C16TMA-V3Index d() 100 51.4 110 29.6 200 26.7 300 17.4

Thermogravimetric analysis for hexagonal structurePowder XRD Patterns for hexagonal structure

Powder XRD Patterns for C16TMA-V1Powder XRD Patterns for C16TMA-V3

Powder XRD Patterns for C16TMA-V5 Index d() 111 44.6 200 38.6 211 31.6 220 27.4 221 25.8 311 23.4 222 22.2C : cubic structure

Powder XRD Patterns for C16TMA-V3TEM image for the sample at 463KThe C16TMA-V3 in ethanol and the pH 2.2 with HCl Resulting brown product was filtered.Hydrothermal reaction at 463K.

Using UV/O3 lamp (electrical power 20W, UV power 5W at 254 and 180nm).Powder XRD Patterns for UV/O3 treated sampleFT-IR spectra for UV/O3 treated sample

I The resulting composites had lamellar structures and displayed mesophase transformation to hexagonal and cubic structures after hydrothermal treatment of vanadate-surfactant composite powders. However, they are thermally unstable. UV/ozone treatment provides an efficient means for the condensation of vanadate clusters, but not efficient for removing of organic surfactant. II

It is speculated that the results are due to the poor condensation of vandates or the strong interaction between the inorganic framework and the organic template.