Abstract This work aimed to study nickel-based oxygen carriers (OC) for Chemical Looping Combustion (CLC) using H2 and CH4 as fuel. The reactivity and reaction kinetics of the OC were investigated, applying the shrinking core, nucleation and diffusion models in three dimensions, as well as whether the OC is thermodynamically favorable for the reaction. The results showed that the OC achieved high conversion for both fuels, proving to be quite reactive, while the fuel gas concentration and the temperature have a strong effect on the solids conversion. For the H2 combustion, the reaction rate can be described well by the shrinking core model, whereas for CH4 the nucleation model may better represent the experimental data. With respect to reactions that occur in the reduction reactor with the NiO/Ni redox system, it was observed that, for the investigated temperatures used in CLC, high values of the equilibrium constant were obtained, showing that practically complete conversion of the fuels is possible.

Este trabalho descreve um estudo sobre a síntese da perovsquita LaNiO3 via método do gel proteico, variando quantidade de colágeno e sobre a atividade catalítica de LaNiO3 e LaNiO3/Al2O3 na produção de gás de síntese (CO + H2). Os padrões de difração de raios X revelaram a formação da estrutura perovsquita em todas as amostras preparadas pelo método de síntese do gel protéico, variando a quantidade de colágeno e após calcinações a 700 ºC por 2 h. O catalisador LaNiO3/Al2O3 preparado pelo método de impregnação mostrou picos de difração nos difratogramas atribuídos a LaNiO3 e ao suporte (Al2O3). Este catalisador apresentou: área superficial específica de 46,1 m² g-1, dois picos de redução no perfil de redução à temperatura programada (RTP) e 46% de conversão do metano (através da oxidação parcial do metano utilizando oxigênio) depois de 18 h de reação.

This work describes a study on the synthesis of LaNiO3 perovskites via the modified proteic gel method, varying collagen content and on the catalytic activity of LaNiO3 and LaNiO3/Al2O3 in the syngas (CO + H2) production. X-ray diffraction patterns revealed the formation of perovskite structure in all samples prepared by proteic gel synthesis method, varying collagen content and after calcinations at 700 ºC for 2 h. LaNiO3/Al2O3 catalyst prepared by the impregnation method showed diffraction peaks due to the perovskite structure and to the support (Al2O3). This catalyst presented: specific surface of 46.1 m² g-1, two reduction peaks in the temperature programmed reduction (TPR) profile and 46% of methane conversion (by the partial oxidation of methane using oxygen) after 18 h of reaction.