Study of the reaction stages and kinetics of the europium oxide carbochlorination

F. J. POMIRO; G.G. FOUGA; J.P. GAVIRÍA; A. E. BOHÉ

METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE

SPRINGER

Año: 2014 vol. 46B p. 305 - 315

1073-5623

The europium oxide (Eu2O3(s)) chlorination reaction with sucrose carbon was studied bythermogravimetry between room temperature and 1223 K (950 C). The nonisothermal thermogravimetryshowed that the reaction consists of three stages, and their stoichiometries werestudied. The product of the first stage was europium oxychloride, and it showed independenceof the reaction kinetics with the carbon content. Subsequently, in the second stage, the Eu-OCl(s) was carbochlorinated with formation of EuCl3(l) and its evaporation is observed in thethird stage. The analysis by Fourier transform infrared spectroscopy of gaseous species showedthat the reaction at second stage occurs with the formation of CO2(g) and CO(g). Both reactantsand products were analyzed by X-ray diffraction, scanning electron microscopy and wavelengthdispersiveX-ray fluorescence spectroscopy. The influence of carbon content, total flow rate,sample initial mass, chlorine partial pressure, and temperature were evaluated. The second stagekinetics was analyzed, which showed an anomalous behavior caused by generation of chlorineradicals during interaction of Cl2(g) and carbon. It was found that the reaction rate at 933 K(660 C) was proportional to a potential function of the chlorine partial pressure whoseexponent is 0.56. The conversion curves were analyzed with the Avrami-Erofeev model and itwas obtained an activation energy of 154 ± 5 kJ mol?1.