Co-TUD-1: a ketone-selective catalyst for cyclohexane oxidation.

Cobalt-containing mesoporous TUD-1 with different Si/Co ratios (100, 50, 20, and 10) was synthesized by the direct hydrothermal treatment method (DHT) using triethanolamine (TEA) as a template. The prepared samples (denoted as Co-TUD-1) were characterized by XRD, UV/Vis spectroscopy, elemental analysis, N2 sorption measurements, 29Si magic-angle spinning (MAS)-NMR, Raman spectroscopy, and HRTEM. The catalytic performance of Co-TUD-1 samples was tested in the liquid-phase oxidation of cyclohexane with tert-butylhydroperoxide (TBHP) as oxidant under solventless conditions. Higher catalytic efficiency was observed in samples with low Co-loading and thus, most likely isolated CoII active sites, than in samples with high Co-loading and nanoparticles or bulk Co3O4 embedded in the TUD-1 silica.