Ti-silicates activate H₂O₂ to form Ti-hydroperoxo and Ti-peroxo intermediates that can react with alkenes to form epoxide products. Comparisons of kinetics for 1-octene epoxidation with H₂O₂ on Ti-BEA and Ti-MFI catalysts with different hydrophilicities in methanol (CH₃OH) or acetonitrile (CH₃CN) solvents show the significance of the solvent for stabilizing catalytically-relevant species and the complex interdependencies between solvent, catalyst topology, and hydrophilicity. Epoxidation turnover rates are higher in CH₃CN than CH₃OH for Ti-BEA, but the opposite trend is observed for Ti-MFI. Ti-silicates with greater silanol densities, however, give greater epoxidation turnover rates than their hydrophobic counterparts in both solvents. Kinetic, spectroscopic, and thermodynamic analyses show that differences in turnover rates mainly arise from changes in the stabilization of reactive surface species by solvent mediated interactions, because the mechanism of the reaction and stability of the fluid-phase reactants remain similar in CH₃CN and CH₃OH. Specifically, apparent activation free energy values ($\mathrm{\Delta }{G}_{\mathit{App}}^{‡})$ indicate that surface intermediates responsible for alkene epoxidation are stabilized to a greater extent in CH₃CN on Ti-BEA and in CH₃OH on Ti-MFI. Hydrophilic Ti-silicates present lower $\mathrm{\Delta }{G}_{\mathit{App}}^{‡}$ values regardless of solvent identity, which suggests that these differences correspond to the number of hydrogen-bonding solvent molecules found near reactive species bound to Ti active sites. Taken together, these findings demonstrate the role of solvent molecules in allowing reactive intermediates to recognize the properties of active sites beyond the length-scale of covalent bonds, which carry implications for epoxidation but also other reactions within solvent-filled pores of microporous materials.

Ti-硅酸盐活化H ₂ O ₂以形成Ti-氢过氧和Ti-过氧中间体，它们可以与烯烃反应形成环氧化物产物。1-辛烯与 H ₂ O ₂在甲醇 (CH ₃ OH) 或乙腈 (CH ₃ CN) 溶剂中具有不同亲水性的 Ti-BEA 和 Ti-MFI 催化剂上的 1-辛烯环氧化动力学比较表明该溶剂对催化稳定的重要性 -相关物种以及溶剂、催化剂拓扑结构和亲水性之间复杂的相互依赖性。CH ₃ CN 中的环氧化转换率高于 CH ₃Ti-BEA 为 OH，但 Ti-MFI 观察到相反的趋势。然而，在两种溶剂中，具有更高硅烷醇密度的钛硅酸盐比它们的疏水性对应物产生更大的环氧化转化率。动力学、光谱和热力学分析表明，转化率的差异主要源于溶剂介导的相互作用对反应性表面物质稳定性的变化，因为反应机理和液相反应物的稳定性在 CH ₃ CN 和CH ₃ OH。具体而言，表观活化自由能值 ($\mathrm{\Delta }{G}_{\mathit{应用程序}}^{‡})$表明负责烯烃环氧化的表面中间体在 Ti-BEA上的 CH ₃ CN 和Ti-MFI 上的CH ₃ OH 中得到更大程度的稳定。亲水性钛硅酸盐含量较低$\mathrm{\Delta }{G}_{\mathit{应用程序}}^{‡}$值与溶剂特性无关，这表明这些差异对应于在与 Ti 活性位点结合的反应性物质附近发现的氢键溶剂分子的数量。总之，这些发现证明了溶剂分子在允许反应性中间体识别超出共价键长度尺度的活性位点的特性方面的作用，这对环氧化以及微孔材料的溶剂填充孔内的其他反应具有影响。