Comparison of the catalytic performance of YIG garnets and Fe-containing oxides catalysts for oxidation of ethylbenzene

Abstract

Iron-containing garnets (YIG) were used as catalysts for selective oxidation of ethylbenzene (EB) in the presence of H2O2 as oxidant. The catalysts comprising of two series of garnets e.g., Y3(Fe1–xZnx)5O12 and Y3(Fe1–xNix)5O12 had distinct Zn and Ni contents (x = 0.00 0.01, 0.03, and 0.05). XRD, Raman and FTIR spectroscopies revealed that the cubic structure of Y3Fe5O12 garnet was present for x = 0.00 and 0.01. For higher contents, the garnets had the Y3Fe5O12 phase besides hematite (α-Fe2O3). The catalytic activity was dependent on the contents of metals in the garnets with Y3Fe4·97Ni0·03O12-γ and Y3Fe4·95Zn0·05O12-γ catalysts achieving better results. The influence of the reaction conditions such as reaction time, reaction temperature and effect of the solvents as well as the substrates to H2O2 molar ratios were studied. SEM-EDS, XPS and EPR results demonstrated the affinity of the Fe2+/Fe3+ pairs with Ni2+ species for the ethylbenzene molecule, which gave an EB conversion of 77% with a good production of acetophenone over the Y3Fe4·97Ni0·03O12-γ catalyst compared to other binary and ternary solids.