A Direct Sol‐Gel Synthesis Method for Incorporation of Transition Metals into the Framework of Ordered Mesoporous Materials

A series of ordered mesoporous cobalt silicate molecular sieves with variable Si/Co molar ratios were hydrothermally synthesized. The materials were characterized by powder X‐ray diffraction (XRD), N₂ adsorption, temperature programmed reduction (TPR), and transmission electron microscopy (TEM). TPR and TEM results indicate that Co introduced by this method is incorporated into the framework of the ordered mesoporous materials rather than residing as Co₃O₄ particles in the pore system. XRD and N₂ adsorption experiments reveal that the interplanar Bragg spacing, surface area, and pore width of the materials are tunable as a function of the bulk Si/Co molar ratio. The surface areas of the materials range from ∼1300 m²/g (unmodified siliceous mesoporous ordered material) to ∼500 m²/g (maximum incorporation of Co before structural breakdown), with the Barrett‐Joyner‐Halenda (BJH) model pore widths varying from 2 to 3 nm, respectively. Vanadium was also introduced by the same method to demonstrate the applicability of the method.

Keywords:

• sol‐gel synthesis
• temperature programmed reduction
• characterization
• adsorption isotherms
• ordered mesoporous materials

Acknowledgments

The authors are grateful to John Walmsley and Randi Holmestad for their help with the TEM images. We also thank the Research Council of Norway (NFR) for financial support.