Low temperature vapor phase selective oxidation of ethylbenzene over Ce1−xMnxO2 nanocubes
•Synthesis of flowerlike ceria and cubic Ce1−xMnxO2 nanocatalysts using nitrate and acetate precursors.•Ce0.25Mn0.75O2 nanocubes were found to be most suitable catalyst for selective oxidation of ethylbenzene.•Catalytic activity of Ce1−xMnxO2 was highly influenced by (1 0 0) plane.•The selective oxidation of ethylbenzene to acetophenone was obtained at a low temperature (463 K).
The Ce1−xMnxO2 nanocatalysts (x = 0, 0.25, 0.50, 0.75 and 1.0 mol. ratio) were synthesized by precipitation method using a different precursor salt. The effect of morphology with exclusive (1 0 0) plane was examined for the selective oxidation of ethylbenzene into acetophenone with maximum selectivity. The physico-chemical properties of synthesized catalysts were characterized using various techniques. The incorporation of Mnn+ into ceria lattice and the presence of (1 0 0) plane were confirmed by XRD and HRTEM analysis. The XRD patterns of Ce1−xMnxO2 catalysts were analyzed using the Rietveld refinement method to calculate the lattice parameters. Surface area and pore size distribution of the catalysts were analyzed from N2 sorption study. XPS and DR–UV–vis spectra confirm the presence of Ce3+ and Mn2+ in the ceria lattice. Further, the presence of Mn2+ in Ce1−xMnxO2 framework was confirmed from ESR technique. H2-TPR study revealed the oxygen storage capacity (OSC) of the catalysts. 3D flower-like and cubic morphology of ceria nanoparticles were confirmed from FESEM and HRTEM images, and the composition values of the elements present in the catalysts were calculated using inductively coupled plasma-optical emission spectroscopy (ICP-OES). The catalytic activity was tested for vapor phase selective oxidation of ethylbenzene using oxygen as an oxidant at low temperature (463 K). The key reaction parameters were varied to study the stability, activity and selectivity of catalysts. The study concluded that suitable amount of manganese ion content in ceria is essential for selective oxidation of ethylbenzene at low temperature (463 K). Cubic structure Ce0.25Mn0.75O2 nanocatalyst with specific (1 0 0) plane is found to be the most suitable catalyst for high conversion and selectivity toward acetophenone under the given reaction conditions.
Graphical abstractOxidation of ethylbenzene into acetophenone over Ce1−xMnxO2 nanocubes using oxygen as oxidant.Figure optionsDownload full-size imageDownload high-quality image (158 K)Download as PowerPoint slide
Journal: Applied Catalysis A: General - Volume 495, 5 April 2015, Pages 92–103