Hydrothermal Synthesis, Crystal Structure, and Catalytic Performance of Four Organic–Inorganic Hybrids Based on Polyoxometalates and O/N-Containing Groups

Abstract

Four new network organic–inorganic hybrid supramolecular compounds [PW12O40](C2H4N3)3·6H2O (1), [PMo12O40](C2H4N3)3·6H2O (2), [H4SiW12O40]8[C6NO2H4]4[C6NO2H5]16[C5NH6]4·39H2O (3) and [H3VW12O40] (C6H6NO2)2(CHO2)2·4H2O (4) composed by keggin type heteropolyanion and O/N-containing organic groups of 1H-1,2,4-Triazole or 2,3-Pyridinedicarboxylic acid have been successfully synthesized by hydrothermally method, and characterized by infrared spectrum (IR), thermogravimetric–differentialthermal analysis (TG–DTA), cyclic voltammetry (CV) and single crystal X-ray diffraction (XRD). Compounds 1–4 exhibit three dimensional supramolecular network via hydrogen bonds and/or π–π stacking interactions. These compounds exhibit good thermal stability and catalytic ability. They are active for catalytic oxidation of methanol in a continuous-flow fixed-bed micro-reactor, when the initial concentration of methanol is 2.5 g m−3 in air and flow rate is 10 mL min−1, the corresponding elimination rates of methanol are 65% (125 °C), 85% (125 °C), 94% (150 °C), and 80% (125 °C), respectively.