SO2 Poisoning Structures and the Effects on Pure and Mn Doped CeO2: A First Principles Investigation

SOx poisoning effects in environmental catalysis have long been recognized as a challenge in development of efficient catalysts for industrial applications. In this paper, a theoretic method combining density functional theory and standard thermodynamic data (enthalpy and entropy) was applied to investigate the SO2 poisoning to pure and Mn doped CeO2 as model catalysts in realistic temperature and pressure. Surface Ce(SO4)(2) rather than Ce-2(SO4)(3) was identified to be the most stable poisoning structure on pure CeO2. The SOx poisoning to the catalysts could not be surmounted simply by heteroatom doping, since the introduction of Mn will enhance the thermal stability of the surface sulfate. The results also indicated that the Lewis acidity of the catalysts could be enhanced by slightly sulfating, which might make some positive effect on catalytic performances for the abatement of environmentally sensitive species including NH3, NO, CO, and hydrocarbons.