A DFT Study on the Mechanism of Catalytic Oxidation Desulfurization Over Ti-MWW Zeolite

In this work, the oxidation mechanism of thiophenic compounds over Ti-MWW zeolite was investigated by DFT-D3 method. Formation energy and activation barrier results indicate that Ti1-η 2 –OOH–H 2 O is the most likely to be the real active center. It was revealed that the reactivity increased in the order of thiophene < benzothiophene < dibenzothiophene < 4-methyldibenzothiophene < 4, 6-dimethyldibenzothiophene, generally consistent with the previous experimental and theoretical results. Independent gradient model analysis suggests a strong interaction between O α and S in transition states, clearly explaining why the oxidation products could be formed readily. At last, the kinetics results show that oxidation desulfurization on Ti-MWW could easily occur at room temperature. The findings can contribute to a better understanding of the oxidative desulfurization mechanism of thiophenic compounds on Ti-MWW zeolite.