Iron(II) Sulfate Oxidation with Oxygen on a Pt/C Catalyst: A Kinetic Study
Статья (Full article),
Kinetics and Catalysis
, E-ISSN: 1608-3210
Институт катализа им. Г.К. Борескова СО РАН
The kinetics of iron(II) sulfate oxidation with molecular oxygen on the 2% Pt/Sibunit catalyst was studied by a volumetric method at atmospheric pressure, T = 303 K, pH 0.33–2.4, [FeSO4] = 0.06−0.48 mol/l, and [Fe2(SO4)3] = 0−0.36 mol/l in the absence of diffusion limitations. Relationships were established between the reaction rate and the concentrations of Fe2+, Fe3+, H+, and Cl− ions in the reaction solution. The kinetic isotope effect caused by the replacement of H2O with D2O and of H+ with D+ was measured. The dependence of Fe2+ and Fe3+ adsorption on the catalyst pretreatment conditions was studied. A reaction scheme is suggested, which includes oxygen adsorption, the formation of a Fe(II) complex with surface oxygen, and the one-electron reduction of oxygen. The last step can proceed via two pathways, namely, electron transfer with H+ addition and hydrogen atom transfer from the coordination sphere of the iron(II) aqua complex. A kinetic equation providing a satisfactory fit to experimental data is set up. Numerical values are determined for the rate constants of the individual steps of the scheme suggested.