Synthesis design of Cu/Al2O3 catalysts to decrease copper leaching in the catalytic wet peroxide oxidation of phenol

Abstract

This work aims to study the catalytic performance of Cu/Al₂O₃ catalysts in the catalytic reaction of oxidation of phenol. The addition of La and Mn to Al₂O₃ support and the calcination temperature influence on the catalytic performance and Cu leaching were studied. The addition of either La or Mn to the support triggered less Cu leaching compared to the unmodified support. The catalysts modified with Mn and calcined at 650ºC and 900 °C yielded low Cu leaching values and high phenol conversions at 120 min of reaction, achieving total consumption of H₂O₂. The catalysts prepared in the same way but modified with La and calcined at 900 °C, achieved 100% phenol conversion and higher TOC conversion. Copper leaching was higher when the support was modified with La, but improved when compared to the unmodified support, suggesting that the presence of Mn allowed a better anchoring of Cu on the support. However, this was not beneficial for the reaction since a certain amount of Cu in the homogeneous phase was required for the reaction to start. Cu-La-Al₂O₃ showed stability after consecutive reaction cycles with the corresponding calcinations in each cycle.