| 초록 |
TS-1, Ti-MCM-41, and SiO2-TiO2-xerogel were prepared using a Ti-Si double alkoxide.precursor, diethoxysiloxane-ethyltitanate (DESET, Gelest, 93.75 mol Si : 6.25 mol Ti). Characterization of the materials prepared were carried out using XRD, N2 adsorption isotherm, SEM, TEM analysis, UV-Vis and FT-IR spectroscopies. Catalytic activity was measured for cyclohexene epoxidation using H2O2 as an oxidant. These studies revealed that samples prepared with the Ti-Si double alkoxide have essentially identical physico-chemical properties to the samples prepared from the conventional chemical sources in the literature, but high titanium amounts in mostly tetrahedral coordination in DESET resulted in higher catalytic activity accompanied by high H2O2 selectivity. Evolution of TS-1 structure using DESET as a precursor was unexpected ,but titanium in the sample was highly unstable and mostly came out from the framework forming large TiO2 clusters upon calcinations. |
