Characterization of active sites of Nb-doped amorphous silicates for ethylene epoxidation Nb-doped amorphous silicates are very promising heterogeneous catalytic materials for rapid and selective epoxidation of ethylene, due to their low economic cost. Although the reaction mechanism has been proposed using a minimal Nb-silica model1, a direct comparison with experimental kinetics data requires considering the local quenched disorder structure of the amorphous silica framework. Therefore, in this contribution, the epoxidation reaction is investigated with more realistic amorphous silica models to mimic the variability of the local structure of the active sites. We study the rate-determining step of the catalytic reaction using density functional theory (DFT) simulations and clusters of various sizes to determine the best computational cost/accuracy balance. We then identify geometrical descriptors that correlate the reaction barrier with the local structure of the active sites and use machine learning2 to estimate effective reaction rates.

Characterization of active sites of Nb-doped amorphous silicates for ethylene epoxidation

ACS Spring 2022

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