Controlling surface chemistry of CO reactions on Fe surface by S blocking: A first-principles and microkinetic studies

Abstract A combination of plane waves first principles approach and microkinetics are employed to study the energetic and kinetics of Fe (110) surface with adsorbates such as carbon monoxide (CO), sulfur (S) and their co-adsorption (CO+S), aiming to investigate the effect of S as an inhibiting agent in the adsorption and dissociation of CO. The structural properties as well as the adsorption energetics of these systems are calculated and analyzed. The presence of sulfur adsorbate on the iron surface is found to reduce the adsorption energy of CO on Fe (110) surface hence lowering its the sticking probability in the surrounding of the adsorbate. Results from our microkinetic model provide insights into how factors such as temperature and partial pressure can be tuned to control the reaction of CO on Fe surface. The calculated kinetic results show that CO adsorbs on the iron surface in molecular state up to 440 K, beyond this threshold temperature CO starts to dissociate into C and O atoms. The introduction of sulfur adsorbate on iron surface increases the threshold of CO dissociation temperature to 480 K emphasizing its impact on the reactivity of carbon monoxide on Fe (110) surface due to the sulfur blocking effect. Finally, we demonstrate that the range of sulfur blocking effect on controlling surface chemistry of CO reactions on Fe surface to be long ranged with respect to the simulation model adopted in this work.