Catalytic Wet Oxidation of Phenol with Mn−Ce-Based Oxide Catalysts: Impact of Reactive Adsorption on TOC Removal

Abstract

Catalytic wet oxidation of phenol solutions at low temperatures of 80−130 °C and space velocities of 1−100 h-1 using Mn−Ce catalysts was studied with an emphasis on the reactive adsorption mechanism and total organic carbon (TOC) removal. Eight catalysts (Mn/Ce = 6:4) were activated under different conditions and promoted with alkali metals (K, Cs) or noble metals (Pt, Ru). The compositions and physical properties of all catalysts were measured. Preliminary runs were conducted in a batch reactor, but most experiments were carried out in a continuous-flow trickle-bed reactor. Catalysts containing mixed Mn3O4−CeO2 phases pure and promoted with alkali metals displayed a higher activity and a higher adsorption of organic deposits on their surface. Noble metals had little effect on process performance. The adsorption capacity of the catalysts was found to be considerably higher than that reported for activated carbon. Furthermore, complete regeneration of a catalyst in three consecutive tests was demonstrated ...