Synthesis of TS-1 using amorphous SiO2 and its catalytic properties for hydroxylation of phenol in fixed-bed reactor Original Research Article

Titanium silicalite-1 (TS-1) has been synthesized using amorphous SiO2 as silicon source and tetrapropylammonium bromide (TPABr) as template. The effects of preparation parameters, such as silicon sources, crystallization temperature and time, aging time, H2O/SiO2, SiO2/TiO2, TPABr/SiO2 and n-butylamine (NBA)/SiO2, and nonionic surfactants on the physicochemical and catalytic properties of TS-1 were investigated in detail. The TS-1 samples were characterized by XRD, FT-IR, UV–vis, SEM, ICP-AES and N2 adsorption. In the fixed-bed reactor, the catalytic property of TS-1 for the phenol hydroxylation was tested. The studies show that the catalytic performance of TS-1 synthesized using amorphous SiO2 is close to that of the samples prepared with tetraethyl orthosilicalite (TEOS) for the phenol hydroxylation with H2O2. The crystallinity of the sample increases with an increase of the crystallization temperature, crystallization time, the ratio of SiO2/TiO2, SiO2/H2O and NBA/SiO2. TS-1 with smaller crystals can be obtained by increasing aging time, H2O/SiO2 and NBA/SiO2, and using the nonionic surfactants. Moreover, adding the nonionic surfactants in the matrix gel can increase the amount of Ti incorporated in framework of zeolite and reduces the amount of TiO2 in an extra framework.