Environmental Catalysis on Iron Oxide–Silica Aerogels: Selective Oxidation of NH3 and Reduction of NO by NH3

Magnetic and Mössbauer spectroscopy studies of nanocrystalline iron oxide aerogels

“…Magnetic iron oxides, such as ␥-Fe 2 O 3 ͑maghemite͒ or Fe 3 O 4 ͑magnetite͒, have been incorporated into SiO 2 aerogel matrices, combining the desirable structural characteristics of the aerogel with magnetic properties of the iron oxide. [1][2][3][4][5][6][7][8] Recently, Long et al 6 adapted a highly flexible sol-gel method to prepare freestanding FeOx aerogels with the specific goal of generating magnetic aerogel nanoarchitectures. Controlled temperature/ atmosphere treatments were applied to convert the amorphous as-prepared FeOx aerogels into mixed-phase nanocrystalline Fe 3 O 4 / ␥-Fe 2 O 3 forms, with the specific crystalline phase being highly dependent on the atmosphere ͑inert versus oxidizing͒ used during the crystallization.…”

Silica aerogel–iron oxide nanocomposites: recoverable catalysts for the oxidation of alcohols with hydrogen peroxide

“…Iron oxide itself exhibits strong acidic and weak redox properties [37]. Most known iron oxide-silica catalysts were prepared with iron nitrate or iron acetylacetonate and with nitrogen-containing bases as gelation agents [14].…”

“…Composites with different oxide/silica ratios and forms have synthesized with various methods for diverse applications, including via a formamide modified sol-gel process [11], Fe 2 O 3 /SiO 2 hollow spheres [12], iron oxidesilica nanocomposite films by spin coating as humidity sensors [13], mesoporous iron oxide-silica aerogels as catalysts for oxidation of NH 3 and reduction of NO [14], Fe-Si mixed oxide nanocomposites that contain iron oxide as the major phase [15], nanocluster iron oxide-silica aerogel catalysts for methanol partial oxidation [16], Fe 2 O 3 -SiO 2 composites, nanosized c-Fe 2 O 3 particles and study on the influence of the iron salts concentration [17], iron oxide-silica nanocomposites with wet impregnation [18], magnetic susceptibility studies of Fe 2 O 3 -SiO 2 [19], Fe 2 O 3 /SiO 2 nanocomposites based on fumed silica (S BET = 265-337 m 2 /g) [20], study of the magnetic properties of the iron oxide particles hosted in silica aerogels pores [21], silica aerogel-iron oxide nanocomposites as catalysts in conjugate additions and in the Biginelli reaction [22]. In spite of these studies, to the best of our knowledge, there is no report on the oxidation of alcohols by silica-iron oxide nanocomposites.…”

Low-temperature SCR of NO with NH3 over noble metal promoted Fe-ZSM-5 catalysts

“…Some transition metal containing catalysts have been investigated for the low temperature SCR reaction, such as chronaia [2], NiSO 4 /Al 2 O 3 [18], MnO x /Al 2 O 3 [19], V 2 O 5 /activated carbon [20], iron-silica aerogels [21], MnO x /NaY [22], MnOx/TiO 2 [23] and other oxides [24]. They showed various SCR activities at below 200°C under different conditions.…”