Synthesis of TS-1 using inorganic SiO2-TiO2 precursor and its catalytic performance for Hydroxylation of phenol

An inorganic SiO2-TiO2 precursor having Si-O-Ti bonds similar to those present in titaniumsilicate molecular sieve was prepared through spontaneous dispersion of Ti(SO4)(2) on amorphous porous silica by thermal treatment. A TS-1 molecular sieve was then synthesized successfully using the inorganic SiO2-TiO2 precursor by hydrothermal crystallization templated by tetrapropylammonium hydroxide. Characterization using X-ray diffraction, Fourier transform infrared spectroscopy, and ultraviolet-visible absorption spectroscopy showed that a higher proportion of titanium species in the precursor with Si-O-Ti bonds was incorporated into the TS-1 framework during the crystallization process, while the titanium species as a bulk TiO2 phase remained unchanged. Conditions affecting the catalytic performance of TS-1 were investigated in detail. The results indicated that the proper conditions were that the treatment temperature for precursor was about 450 degrees C, the molar ratio of silica to titanium was 40, the crystallization temperature was about 160-170 degrees C , and the crystallization time was about 48-72 h. TS-1 prepared under the above conditions showed that the activity for hydroxylation of phenol was comparable to TS-1 made by the classical method.