Assembly of ϵ-Keggin Polyoxometalate from Molecular Crystal to Zeolitic Octahedral Metal Oxide

Chemistry. 2022 Jul 20;28(41):e202200618. doi: 10.1002/chem.202200618. Epub 2022 Jun 10.

Abstract

Zeolitic octahedral metal oxides are inorganic crystalline microporous materials with adsorption and redox properties. New ϵ-Keggin nickel molybdate-based zeolitic octahedral metal oxides have been synthesized. 31 P NMR spectroscopy shows that reduction of MoVI -based molybdates forms an ϵ-Keggin polyoxometalate that immediately transfers to the solid phase. Investigation of the formation process indicates that a low Ni concentration, insoluble reducing agent, and long synthesis time are the critical factors for obtaining the zeolite octahedral metal oxides rather than the ϵ-Keggin polyoxometalate molecule. The synthesized zeolitic nickel molybdate with Na+ is used as the adsorbent, which effectively separates C2 hydrocarbon mixtures.

Keywords: C2 hydrocarbons separation; microporous; nickel molybdate; zeolitic octahedral metal oxides; ϵ-Keggin polyoxometalate.