Catalytic oxidation of acetic acid over sodium titanate synthesized hydrothermally in supercritical water

Sodium titanate was hydrothermally synthesized on the surface of titanium particles in supercritical water. Sodium titanate showed catalytic activity on supercritical water oxidation (SCWO) of acetic acid and promoted oxidation rate greatly comparing to uncatalyzed oxidation. Global rate law based on power-law model and Langmuir–Hinshelwood model could describe experimental results well. In addition, Mars–Van Krevelen model expresses catalytic process well. This suggested that redox reaction over sodium titanate might be a dominant oxidation mechanism, at least, above 450 °C. Deactivated sodium titanate was easily re-synthesized and it recovered catalytic activity. Sodium titanate showed a great potential of a long-term available catalyst in SCWO processes through its cyclic re-activation.

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► Sodium titanate (ST) was in situ synthesized in supercritical water.
► ST can have catalytic activity on supercritical water oxidation of acetic acid.
► ST is stable under supercritical condition but decomposable by sub-critical water.
► Catalytic activity of ST can be easily recovered under supercritical condition.
► ST has a great potential as a long-term available and reactivatable catalyst.