Kinetic Study of Europium Oxide Chlorination

F. POMIRO; FOUGA G. G.; BOHÉ A. E.

METALLURGICAL AND MATERIALS TRANSACTIONS B-PROCESS METALLURGY AND MATERIALS PROCESSING SCIENCE

SPRINGER

Lugar: Berlin; Año: 2013 vol. 44 p. 1509 - 1519

1073-5615

The kinetic of europium oxide (Eu2O3) chlorination using gaseous chlorine as chlorination agent was studied between 250 and 950 °C. The relative mass change during the chlorination reaction was continuously monitored using a high resolution thermogravimetric system. The starting temperature for the reaction of Eu2O3(s) with chlorine was determined at about 250 °C with the formation of solid europium oxychloride (EuOCl). For temperatures above 850 ºC the EuOCl(s) is chlorinated producing EuCl3(l). The influence of gaseous flow rate, sample mass, chlorine partial pressure, and temperature on the reaction rate was analyzed. The results showed that for 400 ºC and temperatures below, the system is under chemical control. Concerning the influence of chlorine partial pressure, it was determined that pressures greater than 50 kPa do not modify the kinetic regime. For the experiment at 400 °C, it was found that the chlorination rate was proportional to a potential function of the partial pressure of chlorine whose exponent is 0.54. The conversion curves were analyzed with the Johnson-Mehl-Avrami description. It was obtained an intrinsic activation energy of 115 kJ·mol-1 for the temperature range of 300 to 400 ºC. Finally, a global rate equation that includes these parameters was developed.