469399 A Theoretical Investigation of Sulfur Adsorption on Calcium Oxide
Although there have been previous experimental studies, the surface mechanism of sulfur retention on Ca-based materials is not well understood. In this study, computational modeling was employed to examine the binding of SOx species to the most prominent AAEM species, calcium oxide. Density functional theory (DFT) calculations were performed using Vienna ab initio Simulation Package (VASP) to investigate the binding mechanism for SOx on a CaO(100) surface. Calculations were also run with various other co-adsorbates, including CO2, H2O and SOx, that are pre-adsorbed to the surface to examine the effect of their presence on any subsequent SOx reactions on the surface. The energetic, geometric and electronic properties of the simulated surfaces were analyzed to discern any possible trends in the SOx binding mechanism with respect to the specific pre-adsorbed molecule. The results were then compared to experimental data where CaO was exposed to a variety of flue gas compositions. In this way, a more complete picture of the SOx binding mechanism on calcium oxide was determined allowing for a better understanding of the initial stages of sulfur capture in combustion systems.
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