Cerium-incorporated cage-type mesoporous KIT-6 materials: Synthesis, characterization and catalytic applications

Ce-KIT-6 with Si/Ce = 5, 10, 20, 50, 100 and 150 mesoporous molecular sieves were successfully synthesized by a hydrothermal method. The synthesized materials were characterized extensively to understand the physico-chemical properties of the materials. The low-angle powder XRD patterns of calcined Ce-KIT-6 material showed a phase that can be indexed to cubic Ia3d. The UV–vis spectra of Ce-KIT-6 samples exhibited two distinct bands with maxima at 265 and 300 nm due to charge transfer to Ce3+ and Ce4+ respectively. Their intensity increased with increase in the Ce content of the samples. The BET surface area was found to be in the range of 668.4–836.9 m2/g. HR-TEM images revealed well-ordered cubic 3-D mesoporous channels. The catalytic activity was tested in the liquid phase oxidation of cyclohexane with hydrogen peroxide. Cyclohexanol was found to be the major product. Ce-KIT-6 (5) gave 74% cyclohexane conversion, which is higher than other catalysts. Ce4+ is suggested to activate hydrogen peroxide by coordination to oxidise cyclohexane.

The large pore cubic Ia3d mesoporous Ce-KIT-6 was successfully synthesized by a hydrothermal method with triblock copolymer Pluronic P123 as the structure-directing agent. The synthesized materials were well characterized. Liquid phase oxidation of cyclohexane to cyclohexanol and cyclohexanone was carried out over Ce-KIT-6 catalyst with different Si/Ce ratios. Ce-KIT-6 (5) is suggested to be a better catalyst than the others.Figure optionsDownload high-quality image (32 K)Download as PowerPoint slide