Article,
Ni-Fe and Co-Fe binary oxides derived from layered double hydroxides and their catalytic evaluation for hydrogen production
CATALYSIS TODAY, 250 (SI): 155-165 (2015)6th International Symposium on Catalysis on Advanced Materials, Cancun, MEXICO, AUG 11-15, 2013.
DOI: 10.1016/j.cattod.2014.08.010
Abstract
Binary oxides based on Co-Fe and Ni-Fe were synthesized thermal
treatment of layered double hydroxides (LDH) having distinct Ni/Fe and
Co/Ni ratios. The solids were characterized through X-ray diffraction
(XRD), Raman and Mossbauer spectroscopy, nitrogen adsorption-desorption
isotherms, thermoprogrammed reduction (TPR) and thermoprogrammed
desorption of CO2 (TPD-CO2), scanning electron microscopy (SEM) and
evaluated in dry reforming of methane. XRD results revealed the spinel
oxides such as NiFe2O4 and CoFe2O4 coexisting with gamma-Fe2O3,
alpha-Fe2O3, Co3O4 and NiO monoxides. These phases were confirmed by
Raman and Mossbauer spectroscopy. Nitrogen adsorption-desorption
isotherms showed a porosity within micro-to-meso pores range, with some
samples displaying macropores. Catalytic evaluation in the dry reforming
of methane by varying the temperature in the 650 and 750 degrees C range
suggested in situ Co /CoFe2O4 and Ni /NiFe2O4 phases formation, which
gives best results with the temperature increment, resulting in H-2/CO
ratios close to 1. The elevated resistance to coking showed by Co-Fe
series is particularly remarkable, however, sintering effects were
observed over these solids. (C) 2014 Elsevier B.V. All rights reserved.
