Zeolitic octahedral metal oxide-based membranes for pervaporative desalination of concentrated brines

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

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 Mo^VI -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.

Zeolitic Vanadotungstates with Ultrahigh Porosities for Separation of Butane and Isobutane

Zeolitic vanadotungstates with tunable microporosity have potential interests in gas separation. The pore openings of the materials are in between the diameters of normal butane and isobutane, which causes the materials only adsorb normal butane. The breakthrough experiments show that the materials effectively separate normal butane from the normal butane and isobutane mixture even at high temperatures. The robust materials can be reused without loss of the separation performance.

Zeolitic Octahedral Metal Oxides with Ultra-Small Micropores for C2 Hydrocarbon Separation

Separation of C₂ hydrocarbons, C₂ H₆ , C₂ H₄ , and C₂ H₂ , remains significant challenges in chemical industry. However, there are only few adsorbents that can effectively isolate C₂ hydrocarbons from their mixtures particularly at a high temperature. Herein, we design a zeolitic octahedral metal oxide based on ϵ-Keggin polyoxometalates with metal ion linkers. Single gas adsorption of the material shows the different adsorption performances for the C₂ hydrocarbons and the strong interaction of the material with the C₂ hydrocarbons. Dynamic competitive adsorption experiments show that the material efficiently separates each of the binary C₂ hydrocarbon mixtures and even the ternary C₂ hydrocarbon mixtures with high selectivity. The material keeps high separation performance even the temperature was increased to 85 °C. The material is stable and is able to be reused without loss of the separation performance.