Banca de DEFESA: MILENA DE SANTANA SANTOS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : MILENA DE SANTANA SANTOS
DATA : 30/08/2019
HORA: 09:00
LOCAL: Instituto de Química
TÍTULO:

PEROVSKITAS BASED ON NICKEL, COBALT AND LANTHANUM APPLIED ON THE PARTIAL OXIDATION OF METHANE AND COMBUSTION BY CHEMICAL CYCLE

PALAVRAS-CHAVES:

methane; perovskites; syngas; chemical looping.

PÁGINAS: 195
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Química Analítica
ESPECIALIDADE: Análise de Traços e Química Ambiental
RESUMO:

Perovskite with composition LaNi_1-xCo_xO₃ (x = 0.0, 0.2, 0.5, 1.0) were studied in the partial oxidation of methane (POX), in the total oxidation (combustion) by chemical looping and in the catalytic combustion of methane. These samples were synthesized by the citrate method and characterized by different methods, such as XRD, specific area by the BET method, TPR-H₂, TPSR-CH₄, XPS, TEM, TGA, Raman spectroscopy were evaluated by TPSR-CH₄/O₂ and by long term tests under different conditions. In POX, the main results indicate that the mechanism of transformation of oxides LaNi_1-xCo_xO₃ (x = 0.2 and 0.5) under atmosphere of CH₄ and O₂ is dependent on the oxide composition (x = 0.2 and 0.5) and pretreatment conditions (in this case, x = 0.2). The sample (x = 0.5), independent of previous H₂ treatment, evidence of the formation of intermediate phases La₂BO₄ (B = Ni and CO) was noted. However, with the sample (x = 0.2) the mechanism involves the formation of the spinel phases (La₂BO₄) only in the condition that there was no pretreatment with H2. In all experiments, the phase changes of the oxides (LaNi_1-xCo_xO₃ and Ni_1-xCo_x/La₂O₃) under atmosphere of CH₄ and O₂ resulted in the
Ni_1-xCo_x/La₂O₃ system. The performance of the catalytic tests in different conditions with the sample (x = 0.2) suggested that the pretreatment with H2 favors the synthesis gas at a H₂/CO ratio closer to the theoretical value (2) when compared to the pre-treatment treatment with the reaction mixture (CH₄ + O₂). During the tests no evidence of catalyst deactivation was observed, but the reaction of OPM contributed to the formation of graphite carbon on these materials. The LaNi_0.5Co_0.5O₃ oxide showed better performance during the chemical cycle combustion tests, this sample led to the complete reduction in a shorter time as well as showed less susceptibility to deactivation due to the formation of coke in the catalytic combustion of methane, all samples were active, it was verified that the addition of cobalt contributed to obtain a more stable catalyst.

MEMBROS DA BANCA:
Presidente - 1100392 - SORAIA TEIXEIRA BRANDAO
Interno - 2494172 - LILIAN MARIA TOSTA SIMPLICIO RODRIGUES
Interno - 2362069 - RAILDO ALVES FIUZA JUNIOR
Externo ao Programa - 2250011 - JAIME SOARES BOAVENTURA FILHO
Externo à Instituição - MARLUCE OLIVEIRA DA GUARDA SOUZA - UNEB