The aim of this work is to evaluate the effect of different fuels in the preparation of Ni-Zn ferrites by combustion reaction. The catalysts were prepared according to the propellants chemistry, in stoichiometric composition, using a vitreous silica container. Carbohydrazine, monohydrated citric acid and glycine fuels were used. During the synthesis parameters as flame combustion time and temperature were measured. The structural and morphological characteristics of the powders were evaluated by XRD, textural analysis by nitrogen adsorption and SEM. The fuel monohydrated citric acid presented the greatest time and temperature of combustion reaction. The results show that the type of fuel changed the final characteristics of the powders. The XRD results showed the formation of Ni-Zn ferrite phase for all fuels used in this study. The powders prepared with carbohydrazine resulted in largest value of surface area. All powders showed morphology constituted by soft agglomerates of nanoparticles.

The aim of this work is to evaluate the esterification and transesterification activity of ZnAl2O4catalysts obtained by different ways of heating during the combustion synthesis using glycine as fuel. Samples were prepared according to the propellants and explosives theory using a vitreous silica crucible as container, and as heating source, plate, muffle furnace and microwave oven. After synthesis, the samples were structural and morphologically characterized by: XRD, nitrogen adsorption and carbon content analysis, and employed in the esterification and transesterification reactions, the percentage of biodiesel formed (FAME) was determined by gas chromatography. The samples obtained on the plate, muffle furnace and microwave showed that even using different heating ways, led to the formation of ZnAl2O4as majority phase, with crystallite sizes of 11, 15 and 10 nm, respectively. The samples present values of surface area ranging from 16 to 77 m2/g, particle size from 17 to 81 nm, and carbon content lower than 11%. The forms used for heating influenced the esterification and transesterification reactions, showing that there was a gap in the production of biodiesel, which is a promising indication that this material has potential to be used as catalysts on the biodiesel production.