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

We examined the H₂- or CH₄-activation behavior taking place at around 300 K on ZnMFI by comparison with the behavior observed in the system including MgMFI, on the basis of the experimental and calculation methods. All experimental data obtained were completely explained with the aid of DFT calculation adopting the M7S2 model which has a specific Al configuration (S2 in our definition) in the M7 site truncated from the MFI structure; the superior electron accepting nature is dominant in the heterolytic dissociation process of H₂ or CH₄ on ZnMFI in comparison with that of Mg²⁺ exchanged on the same site. As a result, we have concluded that the electron transfer (donation) nature from the σ (C–H) ortibal of CH₄ toward the 4s orbital of Zn²⁺ plays an important role in the heterolytic CH₄ activation process. None of the prior studies on the metal-ion exchanged zeolite samples have indicated the presence of a strong correlation with the Al arrangement in the zeolite lattice, although researchers in these fields are aware of the importance of such factor. The present studies will have provided some insights about creating new electronic states ever unknown by utilizing the zeolite matrix with appropriate Al arrangement as the support. We expect that the present work will pave the new way for developing the concept regarding to the synthesis of new materials thus far unknown, as well as the design of new type of catalysts.