Epoxidation of O2 and C3H6 on M1/PTA Single-Atom Catalyst: Theory and Calculation Simulations

Density functional theory (DFT) computational studies of a series of single-atom catalysts (SACs).Geometry of M-1/PTA (M-1 = Mn, Fe, Co, Ru, Rh, Pd, Os, Ir, Pt; phosphor tungstic acid (PTA) = [PW12O40](3-)), different spin multi-gravity, adsorption site screening, metal-support interactions and M-1/PTA SACs catalyzed catalytic cycle for O-2 and olefin oxidation. Studies have shown that the most likely anchoring sites for isolated single atoms on M-1/PTA SACs are quadruple holes on the surface of the PTA support. According to the PTA-Os bond, all single Os-based MOs are responsible for the non-bonding nature. It greatly maintains the catalytic activity of the PTA-loaded single-atom catalyst. Among these M-1/PTA SACs, Os/PTA and Ru/PTA SACs have better activation ability for oxygen molecules, because the catalyst can produce dissociative adsorption of O-2 and greatly weaken the bond energy of the O-O bond. Finally, the mechanism of Os/PTA SAC catalyzing the epoxidation of O-2 and propylene is proposed. The reaction process of Os/PTA SAC activated O-2 with propylene epoxidation, the relative energies, structures of intermediates and transition states were analyzed, and the reaction energy barrier of the rate determination step (RDS) was 24.48 kcal & BULL;mol(-1) for the reaction between the second oxygen atom and C3H6. This indicates the reaction is thermodynamically and kinetically feasible and provides an important and reliable theoretical basis for the experimental synthesis and application.