Oxidation of perchloroethylene-Activity and selectivity of Pt, Pd, Rh, and V2O5 catalysts supported on Al2O3, Al2O3-TiO2 and Al2O3-CeO2

摘要

The total oxidation of perchloroethylene (PCE) over Pt. Pd, Rh and V2O5 metallic monolith catalysts supported on Al2O3 as well as CeO2 and TiO2-doped Al2O3 was examined. To ensure high HCl yields, the amount of water as a hydrogen source was optimized to be 1.5 wt-% by testing the effect of water content on PCE oxidation. Water not only enhanced the selectivity towards HCl formation but also improved the PCE oxidation to some extent.Both, the activity and selectivity of the catalysts were found to be related to the properties of the catalyst support; addition of TiO2 or CeO2 into Al2O3 enhanced catalysts' efficiency regardless of the active phase. Pt, Pd and Rh catalysts showed high catalytic activity, PCE conversions ranging from 72% to 99%, and HCl yields from 59% up to 93% were observed. Both activity and selectivity of the Pt/Al2O3-CeO2 and Pd/AbOs-CeO2 catalysts were superior to the other tested catalysts. The results show that over the oxidation of PCE, the redox properties of the catalyst and the amount of activated oxygen may play bigger role than the acidity. To confirm the suspected positive effect on the PCE oxidation coming from the bidispersed mesopores seen over ceria-doped catalysts needs further testing.