Desenvolvimento de nanoferritas de cobalto para uso com catalisador no processo de WGSR (Water Gas Shift Reaction).

Abstract

The aim of this work was to prepare cobalt ferrites by combustion reaction. The conditions of external heating: ceramic base, resistive muffle furnace, and microwave oven were used in order to investigate the influence on the structure and morphology of the synthesized samples. In order to establish the stoichiometry of the desired phase, samples were prepared according to the theory of propellants and explosives. Temperature of measurement and combustion time flame was performed during the synthesis. The samples of ferrite produced were characterized by X-ray diffraction, infrared spectroscopy, X-ray fluorescence spectroscopy, texture analysis, differential thermal analysis, and thermal gravimetric and scanning electron microscopy. The samples were tested and evaluated the performance in displacement reactions of water vapor (WGSR). The results showed that for every condition of heating used there was the formation of single inverse spinel phase CoFe204, with crystallite size ranging between 38 - 40 nm and anisotropy of planes diffraction. The infrared spectrum showed characteristic bands of tetrahedral and octahedral vibration characteristics of the vibrations of the coordination 4 for iron III cations and 4 and 6, for iron III and cobalt II cations, respectively. The condition of the heating on ceramic base led to the formation of samples with a crystallite size 5.26% greater than other forms of heating and higher surface area (4.194 m2/g). All samples showed a morphology consisting of irregular clusters in the form of sponges with high interparticle porosity. The samples showed mesoporous characteristics with hysteresis type II and loop of hysteresis H3. The sample synthesized in a muffle furnace showed the highest conversion rate of 56% and the sample synthesized in the ceramic base showed greater selectivity with 90.19% for the WGRS system.