Effect of the Chemical Composition of Mesoporous Cerium-Zirconium Oxides on the Modification with Sulfur and Gold Species and Their Application in Glycerol Oxidation

Abstract

Ceria, zirconia, and mixed cerium-zirconium mesoporous oxides were synthesized and used as supports for sulfur and gold species. The materials were characterised using selected advanced techniques (Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), elemental analysis, X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), N 2 adsorption, and desorption isotherms, Ultraviolet-Visible Spectroscopy (UV-vis), Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR), Temperature Programmed Reduction (TPR-H 2 ), Thermogravimetric and Differential Thermal Analysis (TG-DTA)), which allowed for monitoring of the oxidation state of metals (cerium and gold) and the surface properties of the catalysts, in particular the concentration of the components on the surface and in the bulk of materials. The interactions between gold, sulfur, and metals from oxides were considered. The goal of this work was studied the changes in the chemical composition of materials and the oxidation states of cerium species after the modification of oxides with sulfur and gold species and the estimation of the influence of these changes on the surface properties. The chemical composition of surface affects the mobility of surface oxygen and the oxidation state of cerium, which can play the role of redox sites (e.g., Ce 3+ /Ce 4+ species), and therefore it strongly influences the adsorption of hydrogen sulfide and then gold loading. Additionally, gold catalysts modified with sulfur species were tested in the reaction of glycerol oxidation in the liquid phase at basic conditions as the test reaction of the catalytic oxidation of organic pollutants from water.

Effect of the structural integrity on the size and porosity of gold-implanted mixed-metal oxide nanocomposites: their influence on the photocatalytic degradation of thioanisole

“…These results are consistent with the results obtained from the XRD patterns of CeO 2 -ZrO 2 and Au/CeO 2 -ZrO 2 . 39,40…”

“…These results are consistent with the results obtained from the XRD patterns of CeO 2 -ZrO 2 and Au/CeO 2 -ZrO 2 . 39,40 On the other hand, Raman spectra of CeO 2 -Al 2 O 3 show the bands in the range between 600 to 930 cm −1 (Fig. 7) with excitation in the range of 1200 to 1450 cm −1 assigned to the oxygen vacancies in the CeO 2 -Al 2 O 3 support, while in Au/CeO 2 -Al 2 O 3 , these bands appeared with less FWHM, indicating an increased Ce 4+ deficiency by incorporating gold.…”