Synthesis and Use in Catalysis of Hematite Nanoparticles Obtained from a Polymer Supported Fe(III) Complex

Abstract

Dedicated to Prof. Rinaldo Poli on occasion of his 65th birthday.Weakly magnetic hematite (α-Fe 2 O 3 ) nanoparticles were synthesized by heating an amorphous polymer supported iron(III) complex (Fe_POL) at 400 °C for 4 h in air. The growth of nanoparticles (NPs) was studied by PXRD, heating the polymer from 150 °C to 400 °C at 25 °C intervals, revealing that, at all temperatures, the only crystalline phase detected is hematite. Conversely, annealing of Fe_POL at 400 °C for 4 h under nitrogen, yielded a material containing wüstite (FeO) as the only crystalline phase, supported onto pyrolised acrylamidic polymer. The synthesized materials were characterized by TXRF, PXRD, SEM-EDS, XPS, Raman and FTIR spectroscopy as well as by magnetic analysis. Differently from natural micrometric hematite, synthesised nano-hematite turned out to be an efficient and recyclable catalyst for the hydrogenation of nitroarenes to the corresponding anilines.

Direct Observations of Ordered Nanoporosity in Deprotonated 2-(Acetoacetoxy)ethyl Methacrylate (AAEMA–) Polymer: Preliminary Results

“…The microholes might originate from gases released after heating, but we do not have an explanation for the mechanism from which the nanoholes originate. A speculative hypothesis is that the nanoholes are the morphological expression of a local partial order of Fe-POL-forming molecules, as suggested by the by X-ray diffraction pattern [ 14 ] . The perfect alignment of the nanoholes may support this hypothesis, but it is unknown how they formed.…”

“…In a recent study aimed at synthesizing hematite nanoparticles from a polymer supported iron(III) complex [ 14 ], scanning electron microscopy (SEM) observations highlighted that the polymer occurred as “microporous” grains. However, it was unclear whether the Fe-nanoparticles (Fe-NPs) grew within the polymer, or if they filled in the cavities occurring on its surface.…”

Separation of TiO2 and Fe2O3 from Indonesia Ilmenite Minerals and their Application as Photocatalysts for Eriochrome Black‐T Dye Degradation

“…It can be hydrolyzed to hematite (α-Fe 2 O 3 ), maghemite (α-Fe 2 O 3 ), and magnetite (Fe 3 O 4 ). [11] Of the various forms of iron oxide, each has different magnetic properties. Hematite tends to be paramagnetic, while magnetite is ferromagnetic; these two compounds are semiconductors.…”

“…Iron oxide (FeO) in ilmenite is generally in the form of wustite (FeO). It can be hydrolyzed to hematite (α‐Fe 2 O 3 ), maghemite (α‐Fe 2 O 3 ), and magnetite (Fe 3 O 4 ) [11] . Of the various forms of iron oxide, each has different magnetic properties.…”

Hematites Precipitated in Alkaline Precursors: Comparison of Structural and Textural Properties for Methane Oxidation

“…The hematite nanoparticles are obtained either on the wet or dry synthesis. Based on the valence state of Fe, the synthesis includes oxidation from Fe(II) to Fe(III) with oxidants and precipitants [ 13 , 14 ] or the direct preparation of α-Fe 2 O 3 from Fe(III) precursors under various experimental conditions [ 15 , 16 , 17 ]. The performance of α-Fe 2 O 3 strongly depends on the particle size, morphology and structure which are affected by many factors, such as the reactant concentration, the solution pH, the reaction time and temperature and the nature of iron salts [ 18 , 19 ].…”