Banca de QUALIFICAÇÃO: LÍVIA CRISTINA DE OLIVEIRA FELIPE

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : LÍVIA CRISTINA DE OLIVEIRA FELIPE
DATA : 12/04/2019
HORA: 15:00
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: 85
GRANDE ÁREA: Engenharias
ÁREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
ESPECIALIDADE: Cerâmicos
RESUMO:

The production of hydrogen through the dry reforming of methane (DRM) is a process that requires an efficient catalyst, with great stability, and resistance to coke and sintering. Therefore, it is a challenge to find cheap, active and selective catalysts. Nickel-based catalysts have been systematically investigated and have great potential to be used in industrial processes due to their high activity in the methane reforming reaction, as well as being a relatively inexpensive catalyst compared to noble metals. However, they tend to sinter thermodynamically during the reaction and deactivate by deposition of coke. Many papers focus on improving nickel catalysts by choosing suitable supports and promoters. 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. 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 temperatures of 600 °C and 800 °C with space velocity of 36 Lh-1.g-1 for 10h, and after the tests the catalysts were characterized by XRD, TGA, FTIR and SEM-FEG. The XRD patterns show characteristic peaks of the formation of the solid solution Mg0,5Ni0,5O for all the catalysts synthesized, 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. The catalyst La0,2Mg0,8NiO3 showed the best result, with high stability and high conversions of CH4 and CO2.

MEMBROS DA BANCA:
Presidente - 349770 - DULCE MARIA DE ARAUJO MELO
Interno - 6347420 - MARCUS ANTONIO DE FREITAS MELO
Externa ao Programa - 1979301 - RENATA MARTINS BRAGA
Externo à Instituição - RODOLFO LUIZ BEZERRA DE ARAÚJO MEDEIROS - UFRN