Multi-dimensional Crystal Structuring of Complex Metal Oxide Catalysts of Group V and VI Elements by Unit-Assembling

Abstract

Four new porous crystalline complex metal oxide families based on group V and VI elements, all of which are synthesized through unit-assembling, are introduced along with crystal structure formation mechanism. Polyoxometalates (POMs) are utilized as building units and assembled for constructing microporous complex metal oxides. Assembling of MoVO-POMs having pentagonal units of [Mo6O21] with {VO} linkers under hydrothermal conditions forms microporous orthorhombic (NH4)4[Mo30V4O106] {VO}6 oxide and trigonal (NH4)3[Mo19.5V1.5O69] {VO}6 oxide. Assembling of e-Keggin Mo-POMs with bismuth ions as a linker under a hydrothermal condition produces a cubic (NH4)4[Mo9.4V3.6O40] {Bi}2 crystal with cages and channels with the diameter sizes of 0.77 and 0.34 nm, respectively. One dimensional anionic tungstosellenate molecular wire building block, [SeW6O21]2−n, is first formed by linear connection of hexagonal tungstosellenate POM units [SeW6O27] and then linked with the CoII ion to form a crystalline microporous materials, (NH4)0.4 [SeW6O21] {Co(OH)}1.3. [W4O16] building blocks are orderly connected with {VO} linkers to form a microporous framework (K1.5(NH4)0.2H0.3[W4O16]{VO}3) with a pore diameter of 0.43 nm which is fully opened and is accessible to small molecules. These new porous crystalline complex metal oxides showed high catalytic performance for alkane oxidation, aldehyde oxidation, alcohol oxidation, H2O2 oxidation, NH3-SCR, and so on.