Involvement of Solid Acids in the Thermal Decomposition of Calcium Chloride

Abstract

The mechanism and kinetics of thermal decomposition of calcium chloride mixed with various solids such as silica, alumina and titanium oxide were studied at 1 atm and 873K to 1143K. Calcium chloride tends to dissolve into the cage of solid acid at a temperature lower than its melting point. It then decomposes to generate hydrogen chloride in the presence of steam and chlorine in the presence of oxygen or air. The decomposition rate is first-order with respect to the concentrations of both silica and calcium chloride and one-half order to oxygen or steam. The activation energy is 89.0kJ/mol for hydrogen chloride and 70.2kJ/ mol for chlorine. This involvement of silica in the decomposition of calcium chloride has a common feature with the decomposition of chlorides and carbonates of other alkaline metals and alkali earth metals.