Dynamic evolution of titanosilicate precursors: Dual Ti species and their catalytic advantages in selective oxidation

Understanding the detailed structures of active sites and the dynamic nucleation evolution during zeolite precursor formation offers effective guidance on rational design and construction of titanosilicate with optimized performance. Herein, we tracked the evolution of titanosilicate precursors (TSPs) during TS-1 nucleation, revealing the coexistence of dual Ti species, namely highly dispersed amorphous TiO₂ and tetrahedral Ti species incorporated within the silicalite framework. During nucleation, Ti atoms are initially incorporated into silicalite framework and then partially reconstruction into TiO₂ species, displaying a volcano-shaped dependence of tetrahedral Ti proportion on nucleation time. Significantly, the coexisting dual Ti species in TSPs activate highly reactive peroxyl radicals, which selectively promote olefin oxidative cleavage other than epoxidation, differing from the behavior of TS-1 and anatase TiO₂. Our research clarified the dynamic evolution of TSPs and the structure-activity relationship between their dual Ti species and oxidation pathways, thereby guiding the targeted development of titanosilicate catalysts.