Hydrophobized Ti-SiO2 catalysts for the liquid phase epoxidation of olefins
(2023)
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- Titanosilicates (Ti-SiO2) are well-known catalysts for the epoxidation of olefins. Isolated Ti inserted in tetrahedral coordination of the silica framework are the active species. The present thesis proposes the hydrophobization of Ti-SiO2 by organic-functionalization in a one-pot manner as a strategy to boost the catalytic performance in the epoxidation of olefins in liquid phase. First, the synthesis conditions, such as precursor type and molar ratios were optimized to obtain hydrophobic Ti-SiO2 catalysts via one-pot sol-gel procedure. Methyl-functionalized Ti-SiO2 were active, but a positive effect on the catalytic activity could not be totally attributed to hydrophobicity. Second, hydrophobic Ti-SiO2 were produced under the optimized conditions and displayed better performance in the epoxidation reaction than the pristine analogous except at high degrees of methyl-functionalization. Third, the Ti molar ratio was further tuned to prevent the loss of active Ti sites due to methyl-functionalization. However, adjusting the hydrophobic/hydrophilic balance via a one-pot classical sol-gel generally led to detrimental decrease of the Ti dispersion and/or collapse of the pore network. Therefore, mesoporous Ti-SiO2 were synthesized by aerosol-assisted one-pot sol-gel to control the number of Ti active sites, degree of methyl-functionalization, and textural properties simultaneously. These materials exhibited a positive effect of adjusting the hydrophobic/hydrophilic balance on their performance as epoxidation catalysts.
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Manangon Perugachi, L. E. (2023). Hydrophobized Ti-SiO2 catalysts for the liquid phase epoxidation of olefins. https://hdl.handle.net/2078.5/106315