Control Research Of Chelated-iron Regeneration Process In Air-cathode Fuel Cell

The chelated iron method is a typical wet oxidation reduction method based on the ferric (Fe(III))/ferrous (Fe(II)) redox couple.The oxidation of ferrous iron (Fe(II)) in the catalyst regeneration step plays a crucial role in determining the efficiency of chelated-iron process. This work aims to develop a kinetic model that adequately describes the electrochemical and aerobic oxidation kinetics of Fe(II). The speciation of Fe(II) is integrated into the model and kinetic activities of individual chelated-Fe(II) species are quantitatively evaluated. The Fe(OH)(EDTA)3- and Fe(NTA)24" are identified to be the most kinetically active species to be oxidized, and the Fe(EDTA)2-and Fe(NTA)- species show moderate kinetic reactivity in the oxidation. By using such a kinetic model, the oxidation behavior of Fe(II) as a function of solution pH and solution composition is appropriately interpreted in the chelated-iron process. The oxidation rate of Fe(II) in the EDTA-chelated-iron process is mainly controlled by the Fe(EDTA)2- and Fe(OH)(EDTA)3-species, while the Fe(NTA)- and Fe(NTA)24- species are the dominant species responsible for the oxidation kinetics of Fe(II) in NTA-chelated-iron process.Compared with the fast sulfide adsorption reaction, Fe(III) regeneration reaction is relatively slower, and seriously limite the whole chelated iron dehydrosulfurization process.This experiment adopts the impregnation method to modification of anode material, through the preparation of a series of different metal hydroxide/GF material in air cathode fuel cell as anode, to improve the Fe(II) electrochemical oxidation rate. Results show that the Fe(OH)3/GF, Al(OH)3/GF, Mn(OH)2/GF, Co(OH)2/GF, Ni(OH)2/GF, Cu(OH)2/GF, Zn(OH)2/GF, Pb(OH)2/GF eight material as anode material in air cathode fuel cell, the effect of Pb(OH)2/GF is the best, it can not only improve the coulomb efficiency and also can speed up the Fe(II) reaction rate, therefore, select Pb(OH)2/GF as the best anode material.To further explore the influence of anion for Fe(II) electrochemical oxidation rate, using impregnation method prepared a series of different anionic Pb compound/GF,these material as anode in air cathode fuel cell, Though coulomb efficiency and the Fe(II) oxidation rate to assessment the performance of the preparation materials, characterized by cyclic voltammograms, EIS, XRD,The results show that 2PbCO3 · Pb(OH)2GF, PbCl2/GF, PbSO4/GF amd Pb(OH)2/GF all can simultaneously improve the coulomb efficiency and Fe(II) reaction rate, of which PbSO4/GF is the best, coulomb efficiency increased approximately by 20%, accelerated the Fe (Ⅱ) oxidation rate approximately 30 hours.