SYNTHESIS OF Ti-MCM-41 MOLECULAR SIEVES BY ELECTROSTATIC S~+X~-I~+ ASSEMBLY PATHWAY AND ITS CATALYTIC OXIDATION PERFORMANCE

Ti-containing mesoporous molecular sieves Ti-MCM-41 were synthesized by electrostatic S +X -I + assembly pathway.Influences of different factors on the structure of Ti-MCM-41, as well as catalytic oxidation performance of Ti-MCM-41 on many kinds of alkenes were investigated systematically.Only a part of Ti source could be introduced into the framework of Ti-MCM-41 molecular sieve due to the high solubility of Ti under strongly acidic conditions.Ti content in framework decreased with the increase of HCl/TEOS, while the yield, the unit cell parameter a 0 and the framework wall thickness δ w of Ti-MCM-41 molecular sieve increased with the increase of HCl/TEOS.The highly ordered of Ti-MCM-41 molecular sieve could be obtained in the wide range of C 16 TMABr /TEOS(0.3～1.0)and H 2O/TEOS(60～120).The template could be effectively recovered from the Ti-MCM-41 precursor by extraction with a mixed solvent of acetone-water which would not change the ordered structure of Ti-MCM-41 products. Ti-MCM-41 showed catalytic activity to oxidation of many alkenes with hydrogen peroxide or molecular oxygen as oxidizer. The catalytic activity of Ti-MCM-41 from electrostatic S +X -I + assembly pathway was a little lower than that of Ti-MCM-41 from hydrothermal crystallization.