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Iron-alumina materials prepared by the non-hydrolytic sol–gel route: Synthesis, characterization and application in hydrocarbons oxidation using hydrogen peroxide as oxidant

Paper ID Volume ID Publish Year Pages File Format Full-Text
41891 45903 2010 8 PDF Available
Title
Iron-alumina materials prepared by the non-hydrolytic sol–gel route: Synthesis, characterization and application in hydrocarbons oxidation using hydrogen peroxide as oxidant
Abstract

Novel alumina materials containing FeIII ions were prepared by the non-hydrolytic sol–gel route and applied as heterogeneous catalysts in the oxidation of hydrocarbons (cyclooctene and cyclohexane) by the green oxidant hydrogen peroxide. The synthetic route followed an alkyl halide elimination pathway, via etherolysis/condensation between AlCl3 and diisopropyl ether (iPr2O), in the presence of FeIII ions (FeIII:AlIII:iPr2O molar ratio ∼1:15:30). The obtained xerogel (designated FeAlO-50) was thermally treated at 400, 750, or 1100 °C (samples FeAlO-400, FeAlO-750, and FeAlO-1100, respectively), and the resulting materials were characterized by means of different techniques, such as thermal analyses (TG/DTA), ultraviolet–visible (UV–vis) and infrared (FTIR) absorption spectroscopy, X-ray powder diffraction (XRD) and electron paramagnetic resonance (EPR). The concentration of Brönsted acid sites (BAS) at the surface of the samples was also evaluated by adsorption–desorption of cyclohexylamine. The thermal treatments led to truly heterogeneous catalysts, and the FeAlO-1100 material furnished the highest substrate conversion values. The larger catalytic activity of FeAlO-1100 is probably due to the absence of BAS on its surface. Indeed, the other FeAlO samples presented high BAS concentration, and it is known that H2O2 can be non-productively decomposed in the presence of strong acid sites. The catalytic efficiency of FeAlO-1100 can be considered promising (96% cyclooctene and 22% cyclohexane conversions), while the selectivity cyclohexanone/cyclohexanol achieved in the oxidation of cyclohexane was 1.2 (molar ratio). The catalytic systems obtained here are advantageous because they involve the use of H2O2, a green oxidant, and the temperature employed for the oxidation reactions (50–55 °C) is milder than those reported in the literature for other heterogeneous catalyst/H2O2 systems.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (70 K)Download as PowerPoint slideResearch highlights▶ Non-hydrolytic sol–gel route led to real heterogeneous FeIII-alumina catalysts. ▶ FeAlO-1100 furnished a cyclooctene conversion of 96% after 48 h at 50–55 °C. ▶ FeAlO-1100 furnished a cyclohexane conversion of 22% after 48 h at 50–55 °C. ▶ The green oxidant H2O2 was employed in the catalytic systems.

Keywords
Iron(III); Alumina; Non-hydrolytic sol–gel; Heterogeneous catalysis; Hydrogen peroxide
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Iron-alumina materials prepared by the non-hydrolytic sol–gel route: Synthesis, characterization and application in hydrocarbons oxidation using hydrogen peroxide as oxidant
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 389, Issues 1–2, 1 December 2010, Pages 147–154
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us