Aqueous‐phase ketonization of acetic acid over Zr/Mn mixed oxides

Aqueous‐phase ketonization possesses significant advantages over gas‐ or organic‐phase ketonization for improved conversion efficiency of aqueous fraction accompanied by algal bio‐oil production. In this study, synthetized ZrO₂ and Zr/Mn oxides are used for aqueous‐phase ketonization of acetic acid. ZrMn_0.5O_x shows the highest ketonization activity at 340°C for 12 h, achieving maximum acetone yield of 88.27%; and all catalysts exhibited selectivity higher than 96.75%. Apparent activation energy and acid reaction order are 161.2 kJ mol^?1 and 0.70, respectively. Results suggest high ketonization activity of poorly crystallized tetragonal ZrO₂. Addition of Mn results in ZrO₂/MnO_x solid solution and improves active sites. Acid property and Mn⁴⁺ content are important factors, and oxygen vacancy demonstrates relationship with ketonization activity for ZrO₂. Examination of recovered catalysts indicates that ZrMn_yO_x exhibits improved stability, and Mn leaching and crystal phase transformation are main causes of deactivation in aqueous‐phase ketonization. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2958–2967, 2017