Computational Study of the Interactions Between Flue Gas Constituents and Fly Ash Components

Global industrialization and population growth are increasing energy demand. Coal-fired power plants are responsible for generating 40% of the world’s electricity. One promising technology to lower carbon dioxide (CO₂) emissions and other hazardous pollutants is oxy-combustion. By performing the combustion reaction with concentrated oxygen, as opposed to conventional combustion in which ambient air is used, emissions can be drastically lowered and CO₂can easily be captured. Flue gas stream produced by oxy-combustion possesses higher sulfur oxides in comparison to conventional air combustion. One way to mitigate higher sulfur trioxide (SO₃) concentration is through the adsorption onto fly ash. On this project, the interactions of oxy-combustion flue gas components with CaO and MgO found in fly ash are studied. Density functional theory (DFT) calculations are performed utilizing Vienna Ab-initio Simulation Package (VASP) to analyze geometry, binding energy and density of states on individual adsorption as well as coadsorption of SO₂, SO₃, CO₂ and H₂O. This will allow better understanding of sulfur reactions under flue gas conditions.