Thermal and sonochemical synthesis of porous (Ce,Zr)O2 mixed oxides from metal β-diketonate precursors and their catalytic activity in wet air oxidation process of formic acid

Abstract

Porous (Ce0.5Zr0.5)O2 solid solutions were prepared by thermolysis (T=285 °C) or sonolysis (20 kHz, I=32 W cm(-2), Pac=0.46 W mL(-1), T=200 °C) of Ce(III) and Zr(IV) acetylacetonates in oleylamine or hexadecylamine under argon followed by heat treatment of the precipitates obtained in air at 450 °C. Transmission Electron Microscopy images of the samples show nanoparticles of ca. 4-6 nm for the two synthetic approaches. The powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray and μ-Raman spectroscopy of solids obtained after heat treatment indicate the formation of (Ce0.5Zr0.5)O2 solid solutions with a metastable tetragonal crystal structure for the two synthetic routes. The specific surface area of the samples varies between 78 and 149 m(2) g(-1) depending on synthesis conditions. The use of Barrett-Joyner-Halenda and t-plot methods reveal the formation of mixed oxides with a hybrid morphology that combines mesoporosity and microporosity regardless of the method of preparation. Platinum nanoparticles were deposited on the surface of the mixed oxides by sonochemical reduction of Pt(IV). It was found that the materials prepared by sonochemistry exhibit better resistance to dissolution during the deposition process of platinum. X-ray photoelectron spectroscopy analysis shows the presence of Pt(0) and Pt(II) on the surface of mixed oxides. Porous (Ce0.5Zr0.5)O2 mixed oxides loaded with 1.5%wt. platinum exhibit high activity in catalytic wet air oxidation of formic acid at 40 °C.

A High-Efficiency CuO/CeO2 Catalyst for Diclofenac Degradation in Fenton-Like System

“…The characteristic diffraction peaks of CeO 2 in CuO/CeO 2 were slightly broadened compared with that in CeO 2 . This might be associated with the incorporation of Cu 2+ ions with a smaller ionic radius (0.73 Å) compared with Ce 4+ (0.97 Å) (Cau et al, 2014). These phenomena indicated that lattice constriction occurred in CuO/CeO 2 .…”

“…As shown in Figure 5, a strong peak at 462 cm −1 was observed, which was attributed to the vibration mode of the F2 g symmetry in cubic fluorite CeO 2 lattice. This peak of CuO/CeO 2 presented a red shift compared to pure CeO 2 because of the reduction in the lattice parameter as a result of shorter M-O bond length (Cau et al, 2014). The weak band at 1,172 cm −1 was assigned to the second-order phonon mode of fluorite structure.…”

Sonochemical synthesis of LiNi0.5Mn1.5O4 and its electrochemical performance as a cathode material for 5 V Li-ion batteries

“…Sonochemistry has been proven to be green and cost-effective method [22] for the synthesis and coating of nano-sized metal-oxide, composites, and alloys [22][23][24][25][26][27][28]. This technique involves usage of acoustic cavitation phenomenon for the synthesis of different nano/micro-sized materials due to the continuous formation, growth and drastic collapse of bubbles in a solution.…”

Sonochemical precipitation of amorphous uranium phosphates from trialkyl phosphate solutions and their thermal conversion to UP2O7

“…This effect can be employed in many different areas of manufacturing, biotechnology, organic synthesis, and materials chemistry [4,5]. Applications, such as decomposition reactions of precursor compounds lead to the formation of nanoparticles of many important materials, such as metals [6][7][8][9][10], nonmetals [11,12], oxides [13][14][15], chalcogenides [16,17], and phosphates [18][19][20].…”