Synthesis of ceria nanopowders by microwave-assisted hydrothermal method for dry reforming of methane
Résumé
Cerium oxide powder catalyst was prepared by microwave-assisted
hydrothermal synthesis, characterized by physicochemical techniques and
tested in catalytic dry reforming of methane in view of a potential use
as anode material of Solid Oxide Fuel Cells operated on biogas. The
conventional hydrothermal method was also used for comparison to
evaluate the benefits of the non conventional preparation route.
Microstructure and reduction-reoxidation properties of samples prepared
by both routes were studied by XRD, adsorption-desorption isotherms of
N-2 at -196 degrees C, Raman spectroscopy and temperature programmed
reduction in H-2. Repeated cycles consisting of temperature programmed
reduction in CH4 (TPR-CH4) followed by temperature programmed oxidation
in O-2 (TPO) were also performed. The catalytic properties of CeO2
samples were investigated in dry reforming of methane between 750 and
900 degrees C under stoichiometric (0.5% CH4 and 0.5% CO2 in He carrier)
and oxidizing (0.25% CH4-0.75% CO2 in He) conditions. The preparation
under microwave irradiation allows: i) obtaining crystallites with
smaller size, ii) enhancing the stability towards redox treatments, iii)
improving the surface and bulk reducibility by H-2 and CH4, iv)
favoring the creation of defects. These improved properties correlate
well with better catalytic performances in dry reforming of methane with
respect to the conventionally prepared ceria sample. Copyright (C)
2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All
rights reserved.