Solvent Effect Inside the Nanocage of Zeolite Catalysts: A Combined Solid-State NMR Approach and Multiscale Simulation

Solvent effect plays an important role in manipulating the chemical reactivity, equilibrium constant, and reaction rate. Such effect is observed in heterogeneous catalysis, especially for the acidic zeolite catalyst with molecularly size pores (≤1 nm). Nevertheless, it is a great challenge to systematically investigate the intermolecular interaction and the mechanism of solvent effect on the catalytic performance inside the acidic zeolite nanocages. Here, we used the state-of-the-art solid-state NMR (SSNMR) experimental techniques combined with multiscale theoretical simulations to quantitatively investigate the solvent effect on the reactant electronic property and reaction activity. In particular, a series of 13C CP/MAS solid-state NMR experiments with acetone probe for H-ZSM-5 zeolite were performed via changing the coadsorption amount of nitromethane solvent. It is found that the solvent effect accounts for the enhancement of the apparent Brønsted acidic strength of zeolite catalysts, and thus promotes the catalytic reactivity. Furthermore, multiscale theoretical simulations for coabsorption configurations and electronic properties were employed to elucidate the mechanism of solvent effect on the zeolite catalysis. Therefore, so far for the first time the quantitative relationship between solvent effect and the catalytic performance inside the H-ZSM-5 zeolites has been established, and the mechanism of solvent effect in nanocage of zeolites was systematically elucidated.