Synthesis of ceria nanopowders by microwave-assisted hydrothermal method for dry reforming of methane

摘要

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.