Zirconia catalysts (ZrO₂ and Na-ZrO₂) for the conversion of phenethyl phenyl ether (PPE) in supercritical water

In this study, the mesoporous ZrO₂ and Na-ZrO₂ were examined as heterogeneous solid catalysts under supercritical water for the β-ether bond scission of phenethyl phenyl ether (PPE). Na-ZrO₂ was more efficient than ZrO₂ in the dissociation of PPE. Yields of phenol and styrene were 39% and 16%, respectively, under 97% PPE conversion when 2.5 wt.% of Na-ZrO₂ catalyst was applied to a batch reactor filled with supercritical water (400 °C, 20 bar H₂ (initial pressure)) containing 2.5 wt.% PPE. The characterization revealed that the activities of ZrO₂ and Na-ZrO₂ were closely associated with the textural and acid/base properties of the catalysts. Notably, the reaction pathway and product distribution were determined by the concentration of acid and base sites on the catalyst's surface.