Melo, Dulce Maria de AraújoSantana, Lívia Cristina de Oliveira Felipe2023-09-152019-08-26SANTANA, Lívia Cristina de Oliveira Felipe. Efeitos da substituição de La por Mg em óxidos do tipo perovskita La-Ni-O para reforma a seco do metano em baixa temperatura. Orientador: Dulce Maria de Araújo Melo. 2019. 87f. Tese (Doutorado em Ciência e Engenharia de Materiais) - Centro de Ciências Exatas e da Terra, Universidade Federal do Rio Grande do Norte, Natal, 2019.https://repositorio.ufrn.br/handle/123456789/54858Perovskite catalytic materials are potential candidates for the dry reforming of methane (DRM) due to their thermal stability, improved active-metal dispersion and sintering resistance. DRM has been mainly investigated at temperatures above 700 °C to obtain high conversions of CH4 and CO2. However, from an industrial point of view, considering the economic viability, it is desired to operate at lower temperatures (≤600 ºC). The present study evaluates the effect of the substitution of La by Mg on perovskite type La-Ni-O oxides for dry reforming of methane at low temperature, and also evaluates the Gas Hourly Space Velocity (GHSV) in the standard catalyst (LaNiO3). The role of Mg is to increase basicity in order to improve both catalyst activity and suppression of carbon formation. The catalytic precursors were prepared by onestep route using chitosan as chelating agent, and their DRM performances were evaluated at 600 °C, with space velocity of 36 L.h-1.g-1 for 10h. The catalysts were synthesized following the formula La1-xMgxNiO3 (x = 0.2; 0.5; and 0.8), calcined at 900 °C for 3 h and characterized by XRD and TPR. The structure of catalysts during the reduction under H2 atmosphere and during the dry reforming of methane reaction was investigated by in-situ X-ray diffraction, and after DRM reaction the catalysts were characterized by XRD, TG, FTIR, Raman and SEM-FEG. The XRD patterns of the doped samples show characteristic peaks of the solid solution Mg0,5Ni0,5, and as the substitution of Mg for La increases, the amount of this solid solution also increases. In addition, the formation of three ternary phases was identified: LaNiO3, La2NiO4 and La4Ni3O10. There is also an increase in the maximum reduction temperatures as the Mg content in the structure increases, this may be due to the strong interaction between Ni and Mg. After activation of the samples, regardless of the structure, the perovskites show two new phases that correspond to the lanthanum oxide (La2O3) and nickel (Niº) phases. Results after DRM indicate that a fraction of the starting oxide catalyst is converted to La2O2CO3 and that carbon nanotubes was formed on the catalyst surface. The La0,2Mg0,8O3 catalyst stood out due to its high stability and high conversions of CH4 and CO2. However, there is a possibility that the La0,5Mg0,5O3 catalyst will exceed its activity over the longer stability term because of its low carbon deposition.Acesso AbertoPerovskitaMétodo One-StepQuitosanaMgO-NiOReforma a seco do metanodoctoralThesisCNPQ::ENGENHARIAS::ENGENHARIA DE MATERIAIS E METALURGICA