Sulfidation of manganese in H₂S-H₂ atmospheres at temperatures between 1073 and 1273 K

Abstract

The sulfidation behavior of Mn in H₂S-H₂ atmospheres,$10^{ - 8} \leqslant P_{S_2 } \leqslant 10^{ - 4}$ atm, maintained at a total pressure of 1 atm was investigated at temperatures between 1073 and 1273 K. The reaction kinetics obeyed the parabolic rate law; the parabolic rate constant was proportional to$P_{S_{_2 } }^{{1 \mathord{\left/ {\vphantom {1 n}} \right. \kern-\nulldelimiterspace} n}}$ where n=6.1±0.3. A value of 21,000±2000 cal/mole was estimated for the activation energy of the growth of the sulfide scale under constant sulfur pressure. Polycrystalline columnar α-MnS scales were formed which exhibited texture with preferred (111) orientation. The parabolic rate constants at different sulfur pressures from this and previous investigations were used to evaluate the manganese self-diffusion coefficient in α-MnS at$P_{S_{_2 } }$.