Materiais estruturados à base de níquel, cobalto, cobre e manganês para combustão de metano por recirculação química

Abstract

Oxides transition metais, like nickel, copper and manganese has been studied as oxygen carriers in combustion process by Chemical looping. Oxides with perovskite structure type are widely applied in reforming by catalytic properties, thermal and Chemical stability. Because of these properties are promising materiais as carriers of oxygen in combustion processes by Chemical cycles. In this work, ABO3 and A2BO4 perovskite oxides were prepared by microwaves-assisted self-combustion using urea as fuel. The materiais were calcined at 900°C for 2h. After calcination all oxides prepared were impregnated with 20% (m/m) nickel and calcined again at 600°C/2h. The samples were characterized by the following techniques: X-ray diffraction (XRD), temperature programmed reduction (TPR) and scanning electron microscopy (SEM). The carriers were done by Chemical cycles reactions. This experiments can be simulate the CLC process. The analysis system consists of coupling equipment from Micromeritics AutoChem II with a mass spectrometer from Hiden HPR20. The programming pulses of reagents was prepared in AutoChem II system and the exhaust gases were analyzed by Mass Spectrometer. According to the X-ray diffractograms, secondary phases of nickel oxide were formed after impregnation of nickel in powders. The SEM images showed that the impregnation methodology resulted in a homogeneous dispersion of the particles of nickel oxide on the surface of perovskites. The results of the reactions of Chemical cycles showed greater efficiency of carriers impregnated with nickel on its surface.