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

•Na-ZrO2 was active for ether bond cleavage of PPE under supercritical water.•Na-ZrO2 was comparable to homogenous catalysis (Na2CO3) in activity.•Na-ZrO2 was enhanced in BET area and base site concentration.•Na-ZrO2 was more active than ZrO2 in terms of PPE conversion and product yields.•The acid–base concentration governed the reaction pathway and product distribution.

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.

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