Selective synthesis of propylene oxide through liquid-phase epoxidation of propylene with H₂O₂ over formed Ti-MWW catalyst

The liquid-phase epoxidation of propylene to propylene oxide (PO) over formed titanosilicate catalysts was investigated in a fixed-bed reactor. The effects of reaction temperature, n(C₃⁼)/n(H₂O₂) molar ratio, and weight hourly space velocity (WHSV) of H₂O₂ or solvent on the catalytic performance of the formed Ti-MWW catalyst have been extensively studied. Adding an appropriate amount of ammonia to the reaction mixture prolonged the catalyst lifetime effectively. The main byproduct of propylene glycol (PG) and other heavy byproducts with high boiling points were deposited inside zeolite micropores, which corresponded to the main reason for the catalyst deactivation. The high-temperature calcination in air recovered readily the reactivity of the deactivated catalyst. Fluorine implantation remarkably enhanced the reactivity and lifetime of the catalyst in the hydrogen peroxide propylene oxide (HPPO) process, exhibiting a PO selectivity of >99%.