Structure and phase analysis of one-pot hydrothermally synthesized FePO4-SBA-15 as an extremely stable catalyst for harsh oxy-bromination of methane

Authors:  Runqin Wang, Ronghe Lin, Yunjie Ding, Jia Liu, Junhu Wang, Tao Zhang

Abstract:
FePO₄-SBA-15 (OP) was directly synthesized via a one-pot hydrothermal technique, using Fe(NO₃)₃ and H₃PO₄ as the precursors. FePO₄/SBA-15 (IMP) was also prepared as a reference, using an impregnation method and commercially available SBA-15 as the support. The yielding samples were employed to catalyze the harsh oxy-bromination of methane (OBM) reaction, showing similar initial catalytic performances. The fresh and spent samples after catalytic reaction were thoroughly characterized by N₂- physisoption, inductively coupled plasma, wide- and small-angle X-ray diffraction,transmission electron microscopy, diffuse reflectance UV–vis spectroscopy, temperature-programmed oxidation, and room temperature 57Fe Mössbauer spectroscopy. It was found that the FePO₄ was in good crystalline in the OP sample while it was in amorphous for the IMP catalyst. Despite this difference, both FePO₄ phases in the fresh samples were transformed into Fe₇(PO₄)₆ and Fe₂P₂O₇ in the spent ones. Furthermore, the OP catalyst showed excellent stability in a period of 1000 h time-on-stream performance without apparent deposition of cokes. The losses of P and Fe after the catalytic evaluation were only 9.5% and 15.5%, respectively, while the ratio of P/Fe remained close to 1.0. N₂-adsorption and TEM observations confirmed that the mesoporous pores were extremely stable under the harsh reaction ambience, which might play a crucial role in the stability test.

Keywords:
SBA-15
Iron phosphate
Methane
Oxy-bromination
Stability

Published in: Applied catalysis A: General  (Volume 453, Pages 1-402, 26 February 2013)

Publisher: Elsevier

ISSN Information: 0926-860X

Structure and phase analysis of one-pot hydrothermally synthesized FePO4-SBA-15 as an extremely stable catalyst for harsh oxy-bromination of methane

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