Impact of preparation methods on SBA-15 supported low cobalt-content composites: Structure and catalytic activity

• The amount of Co-content affects the morphology of the Co3O4 patches supported on SBA-15.
• At fixed Co-content, the preparation method affects the extent of pore blockage and the accessibility of the Co3O4 species for catalytic activity.
• The catalytic activity of the Co-composites is in reverse proportion to the Co3O4 patches size.

SBA-15 supported cobalt oxide composites with low Co-content (1 wt%) were prepared via the “two-solvent” method and impregnation. The impact of the low Co-content and preparation method on the morphology and dispersion of the resultant Co3O4 particles was investigated using a variety of characterization techniques (XRD, N2 adsorption–desorption, ICP-MS, DR UV–vis, FTIR, TEM, HRTEM and STEM). Here the Co3O4 patches were smaller and better dispersed throughout the support compared to previously reported composites with higher Co-content. As a result, they exhibited better catalytic performance in the liquid phase oxidation of cyclohexanol, benzylalcohol, 1-phenylethanol and norbornene, with tert-butylhydroperoxide (TBHP). The composite prepared by the two-solvent method demonstrated better catalytic activity compared to its analogues with the same Co-content prepared by the impregnation and adsorption methods. This is attributed to less pore blockage and better availability of Co3O4 in this composite.

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