Kinetics of low-temperature chlorination of vanadium pentoxide by carbon tetrachloride vapor

Low-temperature chlorination of vanadium pentoxide by carbon tetrachloride vapor in dilution with nitrogen has been carried out. The effect of time, particle size, partial pressure of CCl^sub 4^ vapor (0.1 to 0.6 atm), and temperature (553 to 788 K) on the extent of chlorination of V^sub 2^O^sub 5^ has been investigated. The extent of chlorination of the oxide is found to increase with a decrease in its particle size. In all cases, the reaction followed a topochemical reaction model, obeying the following relationship: 1 - (1 - α)^sup 1/3^ = kt where α is the fraction of V^sub 2^O^sub 5^ chlorinated in time t and k is the rate constant. The rate constant has been found to be directly proportional to the partial pressure of CCl^sub 4^ (PCCl^sub 4^). The activation energy values between 553 and 643 K and that between 683 and 788 K have been calculated and found to be 38.9 and 11.5 kJ/mole, respectively. Based on the kinetics results, mechanisms of reaction in the two temperature ranges have been suggested. It has been possible to chlorinate V^sub 2^O^sub 5^ at 753 K to about 87 pct in 30 minutes, using a very low partial pressure of CCl^sub 4^ of 0.15 atm. [PUBLICATION ABSTRACT]