KINETICS OF SOLID-STATE REACTION BETWEEN BARIUM CARBONATE AND CUPRIC OXIDE

Abstract

The kinetics and equilibrium of the solid state reaction between barium carbonate and cupric oxide have been examined thermogravimetrically. The reaction rate is found to be dominated by effects of nucleation and diffusion of carbon dioxide produced. A mathematical model incorporating these effects, along with considerations of heat transfer, is found to satisfactorily correlate the conversion-time data. The reaction is found to follow the stoichiometry BaCO3 + CuO half arrow right over half arrow left BaCuO2 + CO2 although at temperatures above 1123 K, some evidence of BaO is also seen through X-ray diffraction. In the pelletized samples, incomplete conversion is noticed indicative of pore closure effects leading to transport limitations. The latter is also independently confirmed by porosity and surface area measurements. Data on the reaction equilibrium are also obtained and, in conjunction with Van't Hoff's relation, are used to obtain a correlation for the endothermic heat of reaction as a function of temperature.