Synthesis of mesoporous niobium oxophosphate using niobium tartrate precursor by soft templating method

Mesoporous niobium oxophosphate (NBP) with high specific surface area (427 m2/g) and narrow pore size distribution (3–15 nm) has been prepared using aqueous solution of niobium tartrate complex, diammonium hydrogen phosphate as precursors and cationic surfactant, tetradecyl trimethylammonium bromide (TTBr) as an organic template. The synthesized material has been characterized by simultaneously recorded thermogravimetric and differential thermal analysis (TG–DTA), fourier transformed infrared spectroscopy (FTIR), high and low angle X-ray diffraction (XRD), N2 adsorption–desorption isotherms, high resolution transmission electron microscopy (HRTEM), 31P solid state magic angle spinning nuclear magnetic resonance (31P MASNMR) spectroscopy and energy dispersive X-ray (EDX) analysis. HRTEM and XRD confirm the formation of mesoporous structure and HRTEM image indicates the formation of wormhole-like mesopores in the synthesized sample. The interaction of pyridine with niobium oxophosphate has been investigated by means of adsorption infrared spectroscopy (FTIR) which shows that both Brönsted and Lewis acid sites are present on the surface of niobium oxophosphate.