日本ゼオライト学会　刊行物 Publication of Japan Zeolite Association

The designed synthesis of zeolite catalysts, with focus on controlling framework structure and heteroatom distribution, enhances their catalytic efficacy. In Methanol-to-Olefins (MTO) reaction, the shape of intermediate species formed in the reaction nanospace influences the major reaction mechanisms and product selectivity. However, observing active intermediate species presents challenges, making it difficult to establish a clear link between catalytic site (i.e., Al atoms) distribution and catalytic properties. Through isotopic labeling experiments, we demonstrate a structure-catalytic performance relationship between Al distribution in ZSM-5 zeolite and methanol-to-olefins reaction behavior, especially in propylene formation. Two ZSM-5 samples synthesized with different organic structure-directing agents exhibit varying Al distributions based on solid-state NMR spectroscopy and constraint index measurements. Despite similar catalytic properties in terms of conversion and selectivity in MTO reaction, transient responses of ¹³C insertion into propylene fragments differ significantly. These results, obtained experimentally, elucidate the relationship between zeolite design and catalytic performance, providing valuable insights into catalyst optimization for desired reactions.