Kinetics of sulfur transfer from H2S to Fe1-xS

The rate of sulfur transfer across the gas/solid interface involving H₂S(g) and Fe_1-xS surface has been investigated using resistance relaxation measurements at 600°C. The rate of the oxidation reaction incorporating sulfur into Fe_1-xS has been found to decrease with sulfur activity (a_S) in the sample as (a_S)^-2/3, while the rate of the reduction reaction corresponding to sulfur loss is found to increase with the sulfur activity as (a_S)^1/3. The kinetic finding has been combined with the appropriate defect models for FeS to identify the rate limiting step for the sulfur transfer reaction from H₂S to FeS. Accordingly, the rate limiting step has been identified to be: H₂S(g) + 2e^-\rightleftharpoons S^2-(ad) + H₂(g). This revised version was published online in July 2006 with corrections to the Cover Date.