Molecular oxygen uptake behavior of crystalline porous complex metal oxide based on ε-Keggin polyoxometalate unit framework

IF 3.9 2区化学 Q2 CHEMISTRY, PHYSICAL

Molecular Catalysis Pub Date : 2024-11-30 DOI:10.1016/j.mcat.2024.114723

Satoshi Ishikawa , Hirokazu Nito , Wataru Ueda

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Abstract

ε-Keggin polyoxometalate based complex metal oxides are composed of the structural arrangement of ε-Keggin [Mo₁₂O₄₀], which connects with octahedral linker, {MO₆}, to form a microporous structure that localizes counter cations X similar to FAU-type zeolites. In the present study, O₂ adsorption properties of these materials (ε-[X]MoMO) are investigated. ε-[X]MoCoO with X = Fe and Cu showed significant O₂ adsorption in an irreversible manner and the adsorption amount was saturated when 1.0 of O₂ was adsorbed in the unit cell. The ε-Keggin unit of these materials were oxidized after the O₂ adsorption at room temperature, resulting in the shrinkage of their lattice. Based on the characterization results and adsorption behavior, we suggest the O₂ adsorption behavior as follows; O₂ can freely access the whole ε-Keggin unit in ε-[Fe or Cu]MoCoO through the micropores involving redox between O₂ and the ε-Keggin unit. The oxidation of this unit reduces the lattice size, which slows down the migration of O₂ and results in the quasi-equilibrium adsorption near the surface. The selection of M element in ε-[Fe]MoMO was also crucial for the O₂ adsorption.

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来源期刊

Molecular Catalysis Chemical Engineering-Process Chemistry and Technology

CiteScore

6.90

自引率

10.90%

发文量

700

审稿时长

40 days

期刊介绍： Molecular Catalysis publishes full papers that are original, rigorous, and scholarly contributions examining the molecular and atomic aspects of catalytic activation and reaction mechanisms. The fields covered are: Heterogeneous catalysis including immobilized molecular catalysts Homogeneous catalysis including organocatalysis, organometallic catalysis and biocatalysis Photo- and electrochemistry Theoretical aspects of catalysis analyzed by computational methods