Exploration of the role of anions in the synthesis of Cr containing mesoporous materials at room temperature

Chromium containing mesoporous silica materials were synthesized via a modified Stöber synthesis at room temperature. The chromium ion loading and the effect of counter ion in the synthesis were studied in detail. The mesoporous materials were extensively characterized by powder X-ray diffraction (XRD), N2 physisorption, Atomic Absorption Spectroscopy (AAS), Fourier-Transform-Infrared Spectroscopy (FT-IR), Diffuse Reflectance Spectroscopy (DRS UV–Vis), hydrogen Temperature-Programmed Reduction (H2-TPR), X-ray Photoelectron Spectroscopy (XPS), and Transmission Electron Microscopy (TEM) studies. A transition from Ia  3¯d cubic phase to p6mm hexagonal or wormhole phases was noted as more amounts of chromium were incorporated into the siliceous materials. Chromium species present in the silica matrix include monochromate, polychromate, and chromium oxide (Cr2O3) clusters.

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► Synthesis carried out at room temperature for Cr containing mesoporous materials.
► Cubic phase formed only at low Cr amounts.
► Cr species present include monochromate, polychromate, and chromium oxide clusters.