Crystal-Plane-Engineered TiO<sub>2</sub>-Anchored Vanadium Single Atoms and Clusters for Boosting Ultradeep Aerobic Oxidative Desulfurization of Diesel
Huifang Cheng, Ziteng Zhang, Lu Zhang, Feng Liu, Jianlin Deng, Mingqing Hua, Ying Cheng, Huaming Li, Jixing Liu, Wenshuai Zhu
Abstract
The crystal plane effect has gained extensive attention in heterogeneous catalysis reactions; however, it is far from being systematically probed in titanium dioxide (TiO 2 )-supported vanadium catalysts. Herein, a series of vanadium (V) single atoms and clusters anchored on TiO 2 with different crystal planes was fabricated by an improved “top-down” protocol. The dispersion state, electronic structure, and redox properties of the V single-atom and VO x cluster-supported catalysts were systematically analyzed by a series of characterization methods, including X-ray absorption near edge structure (XANES) and density functional theory (DFT) calculations, and their catalytic performances were examined for aerobic oxidative desulfurization (AODS) of 4,6-dimethyl-dibenzothiophen (4,6-DMDBT) with O 2 as the oxidant. The results unveiled that the synergistic effect between the V single atom and the VO x cluster perceptibly promoted the catalytic performances of VO x /TiO 2 samples. Therein, VO x /TiO 2 -(001) shows the lowest apparent activation energy ( E a ) value of 46.3 kJ/mol and the optimal AODS performance with complete 4,6-DMDBT conversion to 4,6-dimethyldibenzothiophene sulfone (4,6-DMDBTO 2 ) within 60 min at 120 °C as compared with VO x /TiO 2 -(101) (81.9 kJ/mol and 180 min) and VO x /TiO 2 -(100) (68.0 kJ/mol and 240 min), which should be attributed to its higher V 5+ /V 4+ ratio, the optimal redox behavior of the V species, the moderate adsorption energy between 4,6-DMDBT and VO x active centers, and the synthetic effect of V single atoms and VO x clusters. Moreover, VO x /TiO 2 -(001) exhibits robust durability in seven cycles of reuse, showcasing the potential for practical applications in the future.