Thermochimica Acta, 87 (1985) 219-224 Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands 219 zyxwvutsrqpon ALKALI METAL OXIDES ACTION ON V,O, CATALYSTS USED IN 2-PROPANOL DECOMPOSITION. I. THERMAL DECOMPOSITION AND ELECTRICAL CONDUCTIVITY STUDIES E.A. HASSAN, A.A. SAID and K.M. ABD EL-SALAAM Ass&t University, Faculty of Science, Chemistry Department, Assiut (Egypt) (Received 14 November 1984) ABSTRACT The effect of monovalent ions on the decomposition stages of ammonium metavanadate was studied using TG and electrical conductivity measurements. It has been determined that Li+ ions affect the decomposition process in a different manner from Na+ or K+ ions. The mechanism by which these ions affect the decomposition process is discussed in relation to the defect structure created by the doping process. INTRODUCTION The thermal decomposition mechanisms of many substances pass through a number of stages between the initial and final products [l-3]. The reaction kinetics can be determined using isothermal [4] or non-isothermal weight-loss measurements [5]. Recently, it has been observed by several authors, that doping of solids can markedly influence the reaction rate and the activation energy of solid-phase reactions [6]. The effect of doping has been attributed to the change in the defect structure of reacting substances [7,8]. Decomposi- tion of ammonium metavanadate yields vanadium pentoxide. The inter- mediates have been studied [9]. It is well known that ammonium metavana- date is very senstive to the presence of different foreign substances [lo], especially alkali metal oxides where the net solid products can be used effectively as a catalyst for SO, oxidation [l.l]. Hence, our goal in the current work is to study the influence of the addition of alkali metal oxides on the different decomposition stages of ammonium metavanadate through TG and electrical conductivity measurements. EXPERIMENTAL The parent materials doped with Li+, Naf or K+ ions were prepared by adding calculated amounts of the nitrates of Li+, Na+ or K+ ions in ratios 0040-6031/85/$03.30 Q 1985 Elsevier Science Publishers B.V.