Oxidación anódica de metanol sobre electrodo de iridio en medio ácido

Tesis - Universidad Complutense de Madrid, 1980.Fac. de Ciencias QuímicasTRUEProQuestpu

Oxidación anódica de metanol sobre electrodo de iridio en medio ácido

Tesis - Universidad Complutense de Madrid, 1980.Fac. de Ciencias QuímicasTRUEProQuestpu

Electrooxidation of primary alcohols on smooth and electrodeposited platinum in acidic solution

The electrooxidation of primary alcohols with four to eight carbon atoms on black Pt electrodeposits on gold/quartz, and on commercial bright platinum/quartz electrodes in perchloric acid solution, was studied by cyclic voltammetry (CV) and with the electrochemical quartz crystal microbalance (EQCM). Alcohol physisorption and Pt oxide reduction by chemical reaction with the alcohols were observed, both processes increasing with increasing chain length of the alcohol. Hexanol addition at 0.4 V versus SCE, the potential at which Pt oxidation starts, or higher potentials produced both an anodic current of hexanol electrooxidation and a mass decrease of bright Pt/Q electrodes, which shows unequivocally that the alcohol reduces the Pt oxide chemically

Electrodes Based on Zeolites Modified with Cobalt and/or Molybdenum for Pesticide Degradation. Part I: Physicochemical Characterization and Efficiency of the Electrodes for O2 Reduction and H2O2 Production

© 2018, Springer Science+Business Media, LLC, part of Springer Nature.With the purpose of obtaining inexpensive electrodes for the degradation of organic pesticides by the electro-Fenton reaction, the required H2O2 being obtained by the 2-electron reduction of dissolved O2, we have prepared glassy carbon electrodes coated with a mixture of graphite with Mo- and/or Co-modified zeolites. Three zeolites were used, Linde type A (ZA), Faujasite (ZY), and MFI (ZSM5), whose maximum possible cation exchange, directly given by the Al/Si ratio, and their hydrophilicity increases in the order ZSM5 < ZY < ZA. The zeolites were modified with Mo and/or Co by the wet impregnation method and characterized by different techniques. The outer surfaces of the three Mo-modified zeolites showed Mo-containing grains (in ZA) or needles (in ZY and ZSM5), which could be largely washed away with hot water. Electrodes were made by depositing on a disc of glassy carbon (GC) a mixture of graphite, zeolite, and a b

Catalytic wet peroxide oxidation of phenol over iron or copper oxide-supported allophane clay materials: Influence of catalyst SiO2/Al2O3 ratio

International audienceAllophane clay materials with SiO2/Al2O3 ratios of 1.0 (AlSi1) and 2.2 (AlSi2) were synthesized by a co-precipitation route and further impregnated with iron or copper species. The structure of the parent AlSi1 sample is similar to that of a typical Al-rich soil allophane, while the parent AlSi2 material resembles the structure of a hydrous feldspathoid with a large interspherule surface, thereby exhibiting a high surface area. The ability of the various iron or copper-based allophane samples to behave as efficient and stable catalysts in phenol oxidation using H2O2 was investigated in ambient conditions for the first time. Their structural and textural properties were determined by X-ray diffractometry, N2 adsorption-desorption at 77 K, electrophoretic mobility measurements, infrared spectroscopy, transmission and scanning electron microscopy, as well as by thermo-gravimetric analysis. The catalytic activity of the iron or copper oxide-supported allophanes was markedly influenced by their SiO2/Al2O3 ratio and by their respective structure. The iron-based AlSi2 catalysts with tail-like structure and high surface area proved to be far more active than their corresponding AlSi1 counterparts. The highest catalytic efficiency in terms of total organic carbon abatement was obtained at 40 °C for the calcined iron oxide-supported AlSi2 allophane sample, for which very low leaching level of iron species was noticed (0.37 mg L−1). By contrast, large differences in terms of catalytic efficiency (conversion rates) and stability were observed for the copper-based counterparts, thereby indicating that the iron oxide-supported allophanes with a hydrous feldspathoid structure are highly active and stable in the catalytic wet peroxide oxidation of pheno