Kinetics of Reaction of Steel with Hydrogen Sulfide-Hydrogen Mixtures

The kinetics of the reaction of steel with pure hydrogen sulfide at 250°–500°C may be interpreted in terms of consecutive linear and parabolic rates. In hydrogen sulfide‐hydrogen mixtures similar reactions exist, but the reaction rate decreases as the thermodynamic equilibrium line is approached, in a manner which is approximately proportional to the decrease in the thermodynamic driving force. Increase of pressure up to 20 atmospheres increases the reaction rate by a fractional power of the pressure. In the presence of traces of oxygen, the linear rate component is minimized. The observed kinetics can be explained in terms of three steps: adsorption, rate of formation of diffusing species, and diffusion.