Unveiling the enhanced reactivity of NO ozonation on NH4-SAPO-34 zeolite: Ab initio molecular dynamics combined with experimental characteristics

Abstract

An environmental-friendly NH4-SAPO-34 catalyst, easily obtained via ion exchange, was prepared and tested for its catalytic ozonation activity in NO oxidation under O3-deficient conditions. Characterization results revealed the successful loading of NH4+ on the Brønsted acidity of SAPO-34 after NH4NO3 ion exchange. Surprisingly, the NH4-SAPO-34 zeolite exhibited superior performance in the catalytic ozonation of NO. Ab initio molecular dynamics simulations demonstrated that the facile binding of NO and O3, along with rapid dissociation of the intermediate (NO2 dimer), contributed to the enhanced catalytic performance of NH4-SAPO-34 compared to H-SAPO-34. Additionally, the impact of various ammonium salts on the catalytic activity was investigated, stating clearly the NH4+ coordination in the eight-membered ring windows as the active site. Thus, this study deepens our understanding of the NO ozonation dynamics catalyzed by NH4-SAPO-34 and provides a promising method for synthesizing catalysts without expensive transition metals.