Studies on styrene selective oxidation over iron-based catalysts: Reaction parameters effects

CeFe-Based Bead Nanocomposites as Catalysts for Oxidation of Ethylbenzene Reaction

“…The findings state that the main modes of the Fe-O stretching vibration of α-Fe 2 O 3 appear at E g (620 and 658 cm -1 ). These modes may be overlapped with that at 690 cm -1 from Fe 3+ in distorted tetrahedral symmetry as well as Fe 3+ /Fe 2+ in octahedral symmetry from γ-Fe 2 O 3 [25]. At a high frequency region (Figure 3c), the modes attributable to the vibrations of α-Fe 2 O 3 at 1100 and 1300 cm -1 and the γ-Fe 2 O 3 at about 1370 cm -1 are not visible due to CeO 2 covering the previously mentioned iron phases, as observed elsewhere [17].…”

“…It is noteworthy that the characteristic modes of the iron phases are at about 1100 and 1200 cm -1 (Figure 3c), which are attributed to the α-Fe 2 O 3 (R-3c (D 6 3d ) space group and γ-Fe 2 O 3 (Fd3m (O h 7 ) space group) are not evident in CFC. Clearly, this might be due to either the substitutional doping into the CeO 2 surface lattice by Fe 3+ and Fe 2+ species or the interstitial doping into the CeO 2 surface lattice, which increases the oxygen vacancies [23][24][25].…”

“…The selectivity to others remains high in the case of the binary oxides. Studies on styrene oxidation in the presence of H 2 O 2 reveals that Fe, Ni, and Ce species show a better performance in the reaction at a short reaction time when compared with other solids [25,38,39]. To our knowledge, a reason for the catalytic activity of the solids can be anticipated by noticing that the binary CeFe catalyst offers the acid-base and redox species to accentuate this effect [25].…”

“…Studies on styrene oxidation in the presence of H 2 O 2 reveals that Fe, Ni, and Ce species show a better performance in the reaction at a short reaction time when compared with other solids [25,38,39]. To our knowledge, a reason for the catalytic activity of the solids can be anticipated by noticing that the binary CeFe catalyst offers the acid-base and redox species to accentuate this effect [25]. This supports the idea that the reactivity of the binary nanocasted oxides under study is thanks to the transition metals Fe 3+ /Fe 2+ and Ce 4+ /Ce 3+ pairs having predominant Lewis acid sites, which is demonstrated by using transition metals and which act as catalysts for oxidation reactions [17,39,40].…”

“…The assumed mechanism for others entails the oxidation of the C-H bonds from EB activation by H 2 O 2 to form phenylethyl radicals and hydrogen atoms [25,47]. As a second step, the oxygen radicals react with phenylethyl radicals to yield 1-phenylethylperoxyl one.…”