Unveiling the Roles of Ti Species and Solvent in Propylene Epoxidation With H 2 O 2 Over Titanosilicate‐1 Catalyst Through Density Functional Theory Insights

ABSTRACT The mechanism of propylene epoxidation catalyzed by distinct titanium (Ti) species within the TS‐1 framework was systematically explored through DFT calculations. To elucidate the reaction pathways, rate‐limiting steps, and the intricate relationship between the catalyst structure and performance, several mononuclear Ti active site models, namely TiO 4 , Ti‐IV, Ti‐V, and TiO 6 , were meticulously constructed. The calculation results revealed that for both TiO 4 and TiO 6 , the rate‐limiting step is H 2 O 2 activation, with barriers of 0.75 and 0.77 eV, respectively. In contrast, for Ti‐IV and Ti‐V, the rate‐limiting step is propylene epoxidation, with barriers of 0.74 and 0.47 eV, respectively. Notably, the Ti‐V species demonstrated optimal catalytic activity for both H 2 O 2 activation and subsequent epoxidation, whereas the other three Ti species exhibited comparable catalytic activities. The electronic property calculations provided a robust theoretical basis for the observed activity trends, aligning well with the activation barrier data. Furthermore, the presence of methanol solvent was found to have a remarkable promotional effect on H 2 O 2 activation, significantly altering the kinetic feature of the overall reaction. This effect made the highly coordinated Ti‐V and TiO 6 species particularly promising catalysts for this reaction.