Niobium incorporated mesoporous silicate, Nb-KIT-6: Synthesis and characterization

The direct incorporation of niobium into ordered cubic large pore mesoporous silicate with Ia3d structure, KIT-6, is demonstrated via hydrothermal synthesis using a Pluronic P123 triblock copolymer as the structure directing agent and n-butanol as additive. The synthesized materials, denoted as Nb-KIT-6, were characterized by analytical techniques such as XRD, elemental analysis, N-2 sorption, HR-TEM, Si-29 cross polarization (CP) magic angle spinning (MAS) NMR, Diffuse reflectance UV-Vis, NH3-TPD, pyridine-FTIR and H-2-TPR. The Nb-KIT-6 materials, prepared with various Nb contents, possess high specific surface area (997-804 m(2)/g) and pore volume (1.46-1.12 cm(3)/g) with uniform pore diameter centered around 9.3 nm. The incorporation of most of the Nb in the framework was confirmed by Diffuse reflectance UV-Vis spectra, and contributes to an increase in total acidity. Pyridine FTIR measurements confirm the presence of both Bronsted and Lewis acidic sites, with the total acidity increasing nearly linearly with Nb content. (C) 2014 Elsevier Inc. All rights reserved.