Synthesis, characterization, and catalytic performance of bifunctional titanium silicalite-1

A series of bifunctional Ti-molecular sieves (M-TS-1, M = Al, B, or Fe) containing different trivalent ions (Al3+, B3+, or Fe3+), with MFI topology, were synthesized using tetrapropylammonium bromide, silica sol, and n-butylamine as a template, base, and Si source, respectively. The simultaneous presence of Ti and trivalent ions in lattice positions provided catalysts with activity in both oxidation and acid-catalyzed reactions. The samples were characterized using X-ray diffraction, Fourier-transform infrared spectroscopy, ultraviolet-visible spectroscopy, NH3 temperature-programmed desorption, inductively coupled plasma atomic emission spectroscopy, and N2 adsorption-desorption isotherms. The results showed that the numbers and strength of acid sites of TS-1 were enhanced by the incorporation of trivalent ions. Using selective oxidation of ethylene as the probe reaction, the catalytic properties of M-TS-1 were investigated. The results showed that Al-TS-1 and B-TS-1 had better catalytic properties; conversion and utilization of H2O2 reached 95% and 90%, respectively, and the yield of ethylene glycol plus its monomethyl ether was greater than 10%.

The coincorporation of Ti and a trivalent ion into the MFI-type zeolite was studied. The acidity of TS-1 was enhanced by introducing trivalent ions. M-TS-1 showed higher activity in the selective oxidation of ethylene.Figure optionsDownload as PowerPoint slide