Role of CeO₂ addition to TiO₂-based adsorbent in adsorptive desulfurization: A DFT study

A Ti_xCe_1-xO₂ supported by alumina material was reported recently as a promising adsorbent for Adsorptive desulfurization (ADS) of liquid hydrocarbon fuels. This adsorbent offers good adsorption selectivity for sulfur compounds and good regenerability by using air. The ratios of Ti:Ce were optimized to 9:1 for the maximum adsorption capacity. Previous density functional theory (DFT) work studied adsorption of thiophene over TiO₂ anatase (001) surfaces and found that thiophene could be adsorbed strongly by binding with oxidized (001) surfaces. However, the role of 10% CeO₂ addition to the adsorbent, which increases the adsorption capacity of TiO₂ anatase, remains to be clarified. In this work, first principle calculations were carried out to study the structural dependence of thiophenic compound adsorption over pure TiO₂, pure CeO₂, and Ce-doped TiO₂. The results were correlated with the experimental observations to gain a deeper insight into the adsorptive mechanism of thiophenic compounds on the Ti_0.9Ce_0.1O₂-based adsorbents.