Seed-assisted synthesis of hierarchical nanosized TS-1 in a low-cost system for propylene epoxidation with H_2O_2

摘要

Designing nanosized and hierarchically porous zeolite with intracrystalline mesopores can enhance mass transport ability to improve the catalytic performance of HPPO, which is of prime scientific and industrial importance. Nanosized titanium silicalite-1 (TS-1, 360 x 190 x 640 nm) was first synthesized in a tetrapropylammonium bromide (TPABr)-n-butylamine dry gel system using the seed-assisted method, and postmodification with pure ammonium fluoride (NH4F) solution. This strategy introduced uniform intracrystalline mesoporosity and increased the hydrophobicity. Reducing the TS-1 grain size and creating a hierarchical porous architecture can improve the diffusion of molecules. This solves challenges in mass transport and promotes the catalytic performance. This catalyst was used for propylene epoxidation. The conversion of hydrogen peroxide and selectivity of propylene oxide (PO) attained 98.4% and 97.6%, respectively. Even after 5 runs, the catalyst still maintained a stable performance after simple filtering.