The Chlorination of Zinc Oxide Between 723 and 973 K. A Kinetic Model

DE MICCO G.; FOUGA G. G.; BOHÉ A. E.

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

SPRINGER

Lugar: Berlin; Año: 2007 vol. 38 p. 853 - 862

1073-5615

The kinetics of the chlorination of zinc oxide has been studied by thermogravimetry in the range of temperatures between 723 and 973 K. The starting temperature for the reaction of ZnO with chlorine is determined at about 498 K by a non-isothermal measurement. The influence of gaseous flow rate, sample mass, temperature and chlorine partial pressure in the reaction rate is analyzed. It is established that the reaction occurs under mixed control, being pore diffusion coupled with chemical reaction the rate controlling step. An apparent reaction order of 0.5 with respect to chlorine partial pressure was determined. A kinetic model for the chlorination reaction of porous solids under mixed control is applied. This mathematical description allows to calculate the kinetic parameters: an intrinsic activation energy of 249 kJ mol-1, a zero intrinsic reaction order with respect to partial pressure of chlorine, and to estimate the reaction rate constants for the different temperatures studied