Computational study on adsorption of thiophene over TiO₂ and Ce-doped TiO₂ anatase (001) surfaces

TixCe1-xO2-based material was reported recently as a promising adsorbent for adsorptive desulfurization of liquid hydrocarbon fuels. This adsorbent offers good adsorption selectivity for sulfur compounds and good regenerability by using air. However, the adsorption site and structural dependence of thiophenic compound adsorption over the TixCe1-xO2-based materials remains to be clarified. Determination of the selective adsorption site composition and structure for thiophenic compounds over these materials is necessary for better design and development of the high-performance adsorbents, as well as development of the high-performance catalysts for oxidative desulfurization. In this work, the first principle calculations were carried out. Anatase was used as a basic structure. We first studied the (001) surface because this surface of anatase is relatively stable in thermodynamics, but also reactive in many applications. The adsorption of thiophene on the perfect, O-poor and O-rich (001) surfaces of TiO2 anatase was considered. DFT+U calculations were performed to study the stability of Ce-doped TiO2 bulk and (001) surface. The adsorption of thiophene over Ce-doped TiO2 anatase (001) provides insight into the adsorption mechanism of thiophenic compounds on the TixCe1-xO2-based adsorbents.