Controllable synthesis of niobium doped mesoporous silica materials with various morphologies and its activity for oxidative catalysis

Nb doped HMS-X (Nb-HMS-X) was synthesized by sol gel/emulsion method using non-ionic tri-block copolymer surfactant PEO140PPO39PEO140 (P123) as a structure directing agent. The effect of synthesis condition on the pore morphology and nature of pore ordering was, investigated. Small-angle X-ray Scattering (SAXS) revealed highly ordered pore structure in Nb-HMS-X. It is demonstrated by Field Emission Scanning Electron Microscopy (FESEM) that the materials possessed various morphologies such as, regular spheres, disordered and tube-spheres depending on synthesis conditions. The solid state Si-29 nuclear magnetic resonance measurements showed that chemical environment of silicon atoms get modified significantly with synthesis condition. Furthermore, the synthesized niobium doped hollow mesoporous silica (Nb-HMS-X) was effective to catalyze ethyl benzene oxidation reaction where activation of C-H bond took place. 2015 Elsevier Inc. All rights reserved.