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

Ethane dehydroaromatization (EDA) reaction is one of the promising processes to meet the growing demand of aromatics in the future. Zn ion exchanged MFI type aluminosilicate zeolite (Zn/[Al]-MFI) shows high activity on EDA reaction. Zn ion and Brønsted acid derived from Al sites contribute to the high activity on EDA reaction, but excess strong acid sites promote coke formation, leading to rapid deactivation. Herein, we have developed a new synthesis method for Zn ion exchanged MFI type galloaluminosilicate zeolite (Zn/[Ga,Al]-MFI). The coke formation was suppressed by partially substituting Al with Ga since acidity derived from Ga sites are weaker than that derived from Al sites. We found the different Zn ion exchange phenomena between [Al]-MFI and MFI type gallosilicate zeolite ([Ga]-MFI). Although Zn ion exchange successfully proceed over H⁺ containing [Al]-MFI, the ion exchange over H⁺ containing [Ga]-MFI was hardly occurred. This finding leaded to selective ion exchange from H⁺ to Zn²⁺ derived from Al site over H⁺ containing [Ga,Al]-MFI. Developed Zn/[Ga,Al]-MFI was the ideal catalyst to achieve both high catalytic activity and stability on EDA reaction. Our work provides a new design direction of zeolite catalysts on EDA reaction, which can contribute to the progress on the transformation of light alkanes to value-added chemicals.