Banca de DEFESA: LÍVIA CRISTINA DE OLIVEIRA FELIPE

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : LÍVIA CRISTINA DE OLIVEIRA FELIPE
DATA : 26/08/2019
HORA: 15:30
LOCAL: Auditório do NUPPRAR
TÍTULO:

Effects of Mg Substitutions by La in La-Ni-O Perovskite-Type Oxides in Low-Temperature Dry Reforming of Methane

PALAVRAS-CHAVES:

Perovskite, One-Step Method, Chitosan, Mg, Dry Reforming of Methane.

PÁGINAS: 90
GRANDE ÁREA: Engenharias
ÁREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
ESPECIALIDADE: Cerâmicos
RESUMO:

Perovskite type catalysts are potential candidates for the dry reforming of methane due to their low cost, thermal stability, improved active-metal dispersion and sintering resistance. Due to thermodynamic constraints, DRM has been mainly investigated at high temperatures (>700 °C) to obtain high conversions of CH4 and CO2, however, from an industrial point of view, it is desirable to operate at lower temperatures (≤600 °C). The present study reveals the effect of the substitution of La by Mg on perovskite type La-Ni-O oxides for dry reforming methane at low temperature, besides evaluating the gas hourly space velocity (GHSV) of the standard catalyst (LaNiO3). The catalytic precursors were prepared by a one-step method using chitosan as chelating agent, and their activities for DRM were investigated. For stoichiometric calculations, the formula La1-xMgxNiO3 (x = 0.2, 0.5, and 0.8) was taken as general formula. The catalysts were calcined at 900 °C for 3h and characterized by XRD and TPR. The structure of the catalysts during the reduction under H2 atmosphere and during the dry reforming reaction was investigated by in situ X-ray diffraction. The catalytic tests were performed at temperature of 600 °C with space velocity of 36 Lh-1.g-1 for 10h, and after the tests the catalysts were characterized by XRD, TGA, FTIR, Raman and SEM-FEG. In reactions varying the gas hourly space velocity, increasing GHSV decreases CH4 conversions, indicating that a greater amount of catalyst in the catalytic bed is favorable for DRM. The XRD patterns of replaced samples show characteristic peaks of the formation of the solid solution Mg0,5Ni0,5O, and as the substitution of La by Mg increases, the amount of this solid solution also increases. It is also observed an increase in the maximum reduction temperature as the Mg content in the structure increases, this may be due to the strong interactions that Ni presents with Mg. Results after DRM indicate that a fraction of the starting oxide catalyst is converted to La2O2CO3 and that the presence of the mentioned characteristics strongly confirms the formation of carbon nanotubes. The catalyst La0,2Mg0,8NiO3 showed the best result, with high stability and high conversions of CH4 and CO2.

MEMBROS DA BANCA:
Externa à Instituição - SILVIA LETICIA FERNANDES - UNIFESP
Presidente - 349770 - DULCE MARIA DE ARAUJO MELO
Externa ao Programa - 1979301 - RENATA MARTINS BRAGA
Externo à Instituição - RODOLFO LUIZ BEZERRA DE ARAÚJO MEDEIROS - UFRN
Externo à Instituição - RODRIGO CÉSAR SANTIAGO - UFERSA