Papers by Author: Jean Pierre La Martini Lima Sousa

Abstract: The aim of this work is to evaluate the catalytic activity of NiAl2O4 powders, prepared by combustion reaction with different glycine contents, for the steam reforming of methane. The NiAl2O4 powders were prepared according to the theory of propellants and explosives, using glycine reductant in stoichiometric ratio (Φe = 1) and in excess of 10% and 20% (Φe < 1). During the synthesis, parameters such as flame combustion temperature and time were measured. The samples were characterized by XRD, textural analysis by nitrogen adsorption (BET/BJH), TPR and evaluated as catalysts for the steam reforming of methane. The XRD results showed the presence of NiAl2O4 as major phase and traces of NiO and Ni in all the samples. The glycine content increase caused a decrease of crystallite size and an increase of surface area, from 29 to 39 m2/g. The TPR profiles showed reduction peaks of NiO species in weak interaction with the support, and reduction of nickel present in the NiAl2O4. It was observed that higher methane conversions were obtained in the presence of NiAl2O4 samples prepared using glycine excess. However, it was also observed a rapid deactivation of these catalysts due to high coke deposition onto the active surface phases.

Abstract: CoFe2O4 powders were synthesized by combustion reaction using glycine as fuel, aiming obtaining nanosized and monophase powders. Thus, different conditions of external heating during the synthesis were investigated. The powders were prepared according to the propellants and explosives theory, using glycine as fuel in the stoichiometric proportion (Φe = 1). During the synthesis the flame temperature and time were measured. The resulting powders were characterized by X-rays diffraction and scanning electronic microscopy (SEM). The results show that the condition in which the synthesis was done it influences in the combustion flame temperature and time and contributes for the obtainment of powders with majority phase without secondary phases. Crystallite size varied of 33 to 50 nm. All powders presented morphology constituted by soft agglomerated formed by nanoparticles.