Synthesis of Titanium Silicalite Molecular Sieve TS-2 by Precipitate Silica

Titanium silicalite molecular sieve TS-2 was synthesized by hydrothermal crystallization using precipitate silica as Si source, tetrabutylorthotitanate(TBOT) as Ti source, tetrabutyl ammonium hydroxide(TBAOH) as template. The influences of crystallization temperature and Si/Ti of the pre-gel on the crystallization kinetics and the crystal structure of TS-2 were investigated systematically by using XRD, FT-IR, SEM, UV-Vis on the base of the optimized synthetic procedure. It could be concluded from the experimental results that the optimal crystallization temperature should be 175℃. The higher crystallization temperature readily results in the increase of crystal particle size and the conversion of crystal structure from MEL to MFI. The highest value of Ti/Si(mol/mol) of TS-2 product should be 0.04.The higher value of Ti/Si(0.04) of TS-2 could result in the formation of extra-framework titanium, as well as the decrease of relative crystallinity and catalytic performance.