Effect of the Pt oxidation state and Ce3+/Ce4+ ratio on the Pt/TiO2-CeO2 catalysts in the phenol degradation by catalytic wet air oxidation (CWAO)

Catalytic Wet Air Oxidation (CWAO) of Phenol in a Fixed Bed Reactor Using Supported Ru and Ru‐Au Catalysts: Effect of Gold and Ce Loading

“…Another important contribution by our group was that if the pathway take place by the formation of the quinones, the polymerization on the surface of the catalysts is important thus the deactivation became important due to the block of active sites on the surface of the catalyst . Ce loading effect in this case was important to the enhance the CO 2 selectivity explained by Hosokawa et al, and another authors,,, by the formation of Ce 4+ ‐O 2− ‐M that could favor the oxygen transfer between the catalyst surface and the adsorbed species by a redox mechanism. It's important to remark that the excess of Ce loading (≥ 50%wt) increase the Oxygen Capacity Storage (OSC) which favor the para‐oxidation of phenol entraining the carbon deposit by the polymer formation from p‐benzoquinone and consequently the number of Lewis sites decrease too.…”

“…This effect could be explained as an integration of cerium oxide in the pores and network of zirconia during polymerization reaction by condensation, to saturation in the pores leading to a BET area, pore diameter and pore volume decrease. Studies of various mixed oxides supports, which have been enriched with cerium, suggest a maximum charge between 5–10% CeO 2 wt% in these syntheses, showing increases on the surface areas ,…”

“…The mechanism proposed for these reactions has also been proposed in studies on the phenol catalytic oxidation showing a distribution of similar intermediates in the presence of catalysts of Cu, Ag, Au, Pt and other metals ,,. Catalytic Wet Air Oxidation (CWAO) of phenol is carried out in the solid and liquid phases, the reaction is initiated at the catalyst surface by ionic or radical mechanism, also propagating in the liquid phase; this fact is responsible for the homogeneous contribution to phenol oxidation.…”

“…Ru/ZrO 2 has shown a high catalytic activity in oxidation of organic compounds by WAO, this effectiveness may result from factors such as the synthesis method (precursor salt, heat treatment), metal dispersion, particle size, number of Ru species present, support properties (ZrO 2 ) and reaction conditions (flow rate, pressure and temperature . The synthesis of oxide supports with Ce has shown a high thermal stability and high oxygen storage, attributed to the oxidation states Ce 3+/ Ce 4+ . Previous studies show Au as another noble metal with high oxidizing catalytic activity by WAO with catalysts < 20 nm .…”

Effective p-cresol removal through catalytic liquid-phase oxidation under moderate conditions using Pt/CeO2-ZrO2-SnO2/SBA-16 as a catalyst

“…The generation of oxidized Pt might be related to the redox of the promoter, in which the reducibility of CeO 2 is reported to cause oxidation of Pt through the following reaction: Pt 0 + 2Ce 4+ → Pt 2+ + 2Ce 3+ [30]. Thus, TPR analyses were performed to investigate the reducibility of the promoters, and the TPR profiles are presented in Figure 4.…”