Papers by Keyword: Ti-SBA-15

Abstract: Titanium substituted SBA-15 mesoporous materials have been prepared by direct synthesis under hydrothermal conditions. Ti-SBA-15 was prepared by TiCl₄ and Tetrabutyl titanate (TPOT) as titanium precursor. The synthesized materials were characterized by X-ray diffraction (XRD), UV-Vis spectrometer (UV-Vis), N₂ adsorption/desorption, SEM etc. The results exhibited that the synthesis of mesoporous materials are ordered, and Titanium is tetrahedral and highly dispersed through the inside of SBA-15. Spherical particles of mesoporous have been synthesized by TPOT. The mesoporous materials synthesized by TiCl₄ had non-uniform particle morphology. The titanium precursor TPOT incorporation in SBA-15 makes surface area increase due to make the pore walls slimmer. The titanium precursor TiCl₄ had great influence of the particle morphology and pore characters and no influence on crystal structure.

Abstract: Ti-SBA-15 mesoporous materials with different Si/Ti molar ratios were synthesized via a hydrothermal process and characterized by using various techniques. The effect of Si/Ti molar ratios in the gels on the structure and catalytic efficiency in epoxidation of cyclohexene was discussed in details. The results showed that all the Ti-SBA-15 materials retained SBA-15 mesoporous structure and exhibited good catalytic activity. Furthermore,the sample prepared with Si/Ti =50 exhibited the best catalytic performance under the reaction conditions.

Abstract: Ti-SBA-15 mesoporous materials were directly synthesized via a hydrothermal process and characterized by using nitrogen adsorption-desorption measurements, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, diffuse reflectance ultraviolet-visible spectroscopy, and infrared ray spectroscopy. The effect of synthesis temperatures on the structure and catalytic efficiency in epoxidation of cyclohexene was discussed in details. The results showed that the optimal temperature was 100 °C under the reaction conditions.

Abstract: Mesoporous silica and titanium SBA-15 samples with different Si/Ti molar ratio were prepared by direct one-step synthesis under strongly acidic hydrothermal conditions. The materials were characterised by X-ray diffraction, nitrogen adsorption at 77K. The Si/Ti values of the final calcined materials were determined by ICP analysis. It was found that all samples presented 2-D hexagonal structures with high degree of ordering. However, the metal content incorporated in all titanium mesoporous materials was very low, i.e., the Si/Ti molar ratio values of the final calcined samples are significantly different from the initial Si/Ti molar ratio in the synthesis gel. A study of mechanical stability in air was performed by exposing the calcined samples to a unidirectional external pressure in the range 74-814MPa. X-ray diffraction and nitrogen adsorption at 77K, on selected compacted samples, were used in order to evaluate the changes in mesoporous structure. It was found that, for all freshly calcined pure silica and titanium containing samples tested, the high quality SBA-15 structure is still observed after the application 148-370MPa of a unidirectional external pressure and the collapse of the pore structure occurs at around 814MPa.