Direct synthesis of hydrothermally stable mesoporous Ti-MSU-G and its catalytic properties in liquid-phase epoxidation

Ti-MSU-G has been directly synthesized to investigate its hydrothermal stability and catalytic properties by comparing to pure silica MSU-G and Ti-MCM-41. Ti-MSU-G with ordered mesostructure and containing mainly tetrahedral Ti species in the silica framework is successfully synthesized in the Si/Ti ratio range of 30-70. Showing superior hydrothermal stability to MCM-41, Ti-MSU-G withstands the treatment in boiling water up to 75 h. No Ti leaching occurs when Ti-MSU-G catalyst is used repeatedly in the epoxidation of cyclohexene with either hydrogen peroxide or tert-huty\ hydroperoxide (TBHP). Nevertheless, the states of tetrahedral Ti species of Ti-MSU-G prove to be more stable in TBHP than in aqueous H₂O₂.