Grafting Ti Sites on Defective Silicalite-1 via TiCl4 Chemical Vapor Deposition for Gas-Phase Epoxidation of Propylene and H2O2 Vapor

The gas-phase epoxidation of propylene and hydrogen peroxide (H2O2) vapor to produce propylene oxide (G-HPPO) is a good way to bypass the methanol solvent problem faced by the liquid-phase HPPO process. In order to quell the decomposition of H2O2 while promoting the epoxidation of propylene with H2O2 at a high temperature (e.g., 140 °C) condition generally needed for G-HPPO, an attempt of grafting Ti atoms onto a defective silicalite-1 (S-1) zeolite via the chemical vapor deposition (CVD) of TiCl4 was made as an unconventional route to reach a better catalyst than the hydrothermally synthesized TS-1 zeolite. Results show that the defective S-1 zeolite properly treated with TiCl4 CVD method attained 1.20 kgPO·h–1·kgcatal–1 PO productivity together with 64.62% H2O2 utility at a molar ratio of propylene to H2O2 about 4. These encouraging results highlight the potential of titanium silicalite innovation for the gas-phase epoxidation of propylene with H2O2 vapor.