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Pt nanoparticles and a CeMnO_x composite were loaded on the surface of the natural diatomite material to generate the Pt/CeMnO_x/diatomite using the redox precipitation and impregnation methods. The physicochemical properties of the catalysts were characterized by means of various techniques. The catalytic properties and resistance to H₂O and SO₂ of the catalysts were measured for the oxidation of typical volatile organic compounds (i.e., toluene and ethyl acetate). Among all of the as-prepared samples, Pt/CeMnO_x/diatomite exhibited the highest catalytic activity: the temperatures (T_90%) at a toluene or ethyl acetate conversion of 90% were 230 and 210 °C at a space velocity (SV) of 20,000 mL g⁻¹ h⁻¹, respectively, and the turnover frequency (TOF_Pt) at 220 °C was 1.04 μmol/(g_cat s) for ethyl acetate oxidation and 1.56 μmol/(g_cat s) for toluene oxidation. In particular, this sample showed a superior catalytic activity for ethyl acetate oxidation at low temperatures, with its T_50% being 185 °C at SV = 20,000 mL g⁻¹ h⁻¹. In addition, the Pt/CeMnO_x/diatomite sample possessed good sulfur dioxide resistance during the toluene oxidation process. In the presence of SO₂, some of the SO₂ molecules were adsorbed on diatomite, which protected the active sites from being poisoned by SO₂ to a certain extent. The pathways of ethyl acetate and toluene oxidation over Pt/CeMnO_x/diatomite or Pt/CeMnO_x were as follows: The C–C and C–O bonds in ethyl acetate are first broken to form the CH₃CH₂O* and CH₃CO* species or toluene is first oxidized to benzaldehyde and benzoic acid, and all of these intermediates are then converted to CO₂ and H₂O. This work can provide a strategy to develop efficient catalysts with high catalytic activity, durability, low cost, and easy availability under actual working conditions. Full article

Developing CeO₂-diatomite composites with highly efficient photocatalytic performance is a practical and low-cost strategy for the removal of abundant contaminants in water and wastewaters. Diatomite (D) was modified by acid treatment to obtain a more porous structure. CeO₂-diatomite composites were prepared in two different mass ratios of D to CeO₂ of 1:1 and 1:2 via a facile precipitation method. The changes in structural, morphological, optical, and thermal properties of CeO₂-diatomite composites were characterized by FTIR, XRD, ESEM-EDAX, BET surface area, TGA, PL, Raman spectroscopy, and zeta potential techniques. ESEM images presented the morphological differences of CeO₂-diatomite composites, reflecting the effect of modification as a more folded sheet form morphology and higher BET surface area. XRD analysis revealed the fluorite-type structure of CeO₂ particles in composites. Photocatalytic activities were investigated by following the degradation of methylene blue (MB) as a thiazine dye model under UVA light irradiation. CeO₂-diatomite composites exhibited irradiation time- and dose-dependent remarkable photocatalytic efficiencies, whereas composite type inconsistent variations were also noticed. The attained performance of the CeO₂-diatomite composites could strongly imply a favorable application prospect in the photocatalysis field. Full article