Thermal stability effect of H4[PVMo11O40]/SiO2

Abstract

Synthesis and characterization of supported polyoxometalate  H₄[PVMo₁₁O₄₀].nH₂O with SiO₂ through sol-gel method have been done. The compound H₄[PVMo₁₁O₄₀]/SiO₂ was characterized through FT-IR spectrophotometer, XRD, and SEM-EDX. The results showed that FT-IR spectrum of H₄[PVMo₁₁O₄₀]/SiO₂ has the primary vibration on wavenumber at 1064.7 cm^-1 (P-O); 964.4 cm^-1 (Mo=O); 864.1  cm^-1 (Mo-O_e-Mo); 779.2 cm^-1 (Mo-O_c-Mo); 462.9 cm^-1 (Si-O); and 1087.9 cm^-1 (Si-O-Si). The XRD diffraction pattern showed that H₄[PVMo₁₁O₄₀].nH₂O has the highest crystallinity. However, after it’s supported with SiO₂, the properties of crystallinity has decreased due to the excess water during the support process. The result of SEM-EDX showed that H₄[PVMo₁₁O₄₀]/SiO₂ material has homogeneous distribution with particle size distribution of 1330 nm (1,33 μm). The acidity test by qualitative and quantitative methods show that H₄[PVMo₁₁O₄₀]/SiO₂ more acidic than H₄[PVMo₁₁O₄₀].H₂O. The effect temperature on the crystallinity showed that increasing calcination temperature made the crystallinity properties of  H₄[PVMo₁₁O₄₀]/SiO₂ increased.

Keywords : polyoxometalate, H₄[PVMo₁₁O₄₀].nH₂O, SiO₂.