PREPARATION OF TS-1 BY WETNESS IMPREGNATION OF AMORPHOUS SIO2-TIO2 SOLIDS - INFLUENCE OF THE SYNTHESIS VARIABLES

TS-1 has been synthesized by wetness impregnation of amorphous SiO2-TiO2 solids with TPAOH solutions and subsequent crystallization under autogenous pressure, the influence of the different variables involved being studied, The SiO2-TiO2 cogel used as raw material has been prepared following a two step (acid-base) sol-gel process which leads to the formation of Si-O-Ti bonds previously to the zeolite crystallization. The titanium content of TS-1 can be controlled through the variation of the raw SiO2-TiO2 composition, although a limit of the Ti/(Ti+Si) X 100 molar ratio around 2.3% in titanium effectively incorporated to the zeolite framework has been observed, even when starting from cogels with low Si/Ti ratios. The size and morphology of the crystals depend on the synthesis variables, small crystallites with 0.2 mu m of diameter being obtained at high TPAOH concentration. The kinetics of TS-1 crystallization by this method is very fast in spite of taking place in static conditions. Thus, pure TS-1 can be achieved at 170 degrees C in just 6 h of synthesis. All TS-1 samples were tested as catalysts for n-hexane oxyfunctionalization, high activities and selectivities being obtained with most of them.