Understanding the role of sulfur in controlling carbon monoxide reactivity on iron surface: A DFT and Microkinetic perspective

The corrosive disintegration of metals and their alloys into fine particles occurring in carbon saturated environment at catalytic operating temperatures might lead to serious economic implications on several industrial processes especially in the oil and gas sector. One way proposed to tackle this issue during operation involves the addition of Sulfur-based compound/gases. The addition of small concentration of H₂S to syngas mixture has been shown to prevent failure of the reactors. In order to effectively validate this approach, it is essential to understand at the atomic scale the role of S on the reaction of CO on the metal surface. A combination of plane waves first principles approach and microkinetic was employed to study clean and defective iron surfaces as well as surfaces with CO, S, CO+S adsorbates, aiming to investigate the effect of S as an inhibiting agent in the carburization process of Fe. Our investigation looks to determine if the blocking effect acts at a short or long-range effect. The presence of S is found to reduce the adsorption energy of CO on Iron hence lowering the sticking and dissociative probabilities.