Enhancing the accessible TiO6 concentration and the hydrophobicity of hierarchical TS-1 zeolites for alkene epoxidation and oxidative desulfurization

Abstract

The accessible TiO6 concentration and the hydrophobicity of hierarchical TS-1 zeolites are both considered as critical factors for promoting the catalytic performance of selective oxidation. However, simultaneously enhancing these two factors still remains a challenge. Herein, hierarchical TS-1 zeolites with high hydrophobicity and concentration of accessible TiO6 were fabricated via sequential amphiphilic organosilane-assisted pre-treatment, dry-gel conversion and hydroxyl radical post-treatment, using amphiphilic organosilane and surfactant as meso-porogens. The synthesis mechanism was investigated, and it was found that the interaction between the amphiphilic organosilane and Ti species formed during the pre-treatment benefited the formation of accessible TiO6 during the subsequent dry-gel conversion. During the post-treatment of zeolite with H2O2 solution under ultraviolet light irradiation, appropriate H2O2 concentration facilitated the generation of hydroxyl radical and thus enhanced the hydrophobicity of zeolite without significantly influencing the TiO6 concentration. The hierarchical TS-1 displayed excellent catalytic performances in 1-hexene epoxidation and oxidative desulfurization, with conversion improvements of 91.2%±2.8% and 348%±17%, respectively, compared with the conventional counterpart.