Thermal analysis and kinetics of oxidation of “TiS 2” and “Ti 2S 3”

Abstract

The thermal analysis and kinetics of oxidation of “TiS 2” and “Ti 2S 3” to TiO 2 (anatase) were studied by using both isothermal and non-isothermal thermogravimetry in the oxygen partial pressure, P O 2 , range from 1 to 10 −3 atm. The initial stage of the oxidation process (α = 0.03 to 0.65) was controlled by [-1n(1 − α)] 1 1.5 = kt The apparent activation energies for this stage were determined to be 142.93±2.17 and 160.13±7.17 kJ mol −1 for “TiS 2” and “Ti 2S 3”, respectively over the temperature range 375–450°C and P O 2 range 4.50×10 −2 to 1.29×10 −1 atm. Insufficient P O 2 (<4.50 × 10 −2 atm) was shown to be a major contributing factor to the decrease of E with increasing amount of sample. The latter stage of oxidation (α = 0.65 to > 0.90) was controlled by [( 1 (1−α) 1 3 )−1] 2 = kt and the activation energies were found to be 126.30 ±5.96 and 156.97±13.4 kJ mol −1 for “TiS 2” and “Ti 2S 3”, respectively, over the same temperature and pressure ranges as mentioned above.