Abstract
Ti-MCM-41 mesoporous molecular sieves with Si/Ti=20 were synthesized and modified by treatment with alkaline and ammonium salt aqueous solution, and characterized by XRD, N 2 physisorption, DRIFT, 29 Si MAS NMR, Raman and UV-Vis-DRS analysis. Titanosilicates MCM-41 treated with alkaline salts exhibited mainly basic properties, whereas ammonium salt treatment maintained acid properties of Ti-MCM-41 materials. The resulting acidic Ti-MCM-41 materials were active and selective catalysts for epoxidation of cyclohexene with TBHP. Ti-MCM-41 catalysts with basic properties showed lower activities and selectivities. Moreover, post-synthesis salt treatment did not change the hydrophilic nature of Ti-MCM-41. As a result, the catalysts were rapidly deactivated by water which made them unsuitable for cyclohexene epoxidation with hydrogen peroxide.
Published Version
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