Banca de QUALIFICAÇÃO: GUSTAVO FELIX BITENCOURT
Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.DISCENTE : GUSTAVO FELIX BITENCOURT
DATA : 29/04/2024
HORA: 15:00
LOCAL: https://conferenciaweb.rnp.br/sala/dalmo-2
TÍTULO:
Unveiling a robust Fe-Ga metal-organic framework catalyst for direct methane oxidation
PÁGINAS: 20
RESUMO:
Controllable methane oxidation directly into higher value-added products under mild conditions remains a challenge due to the C-H bond inertness. To promote the oxidation of methane using metal-organic frameworks, it was necessary to explore means of stabilizing Fe-based MOFs due to the leaching and near-complete degradation of the catalyst after exposure to oxidative environments. A structure engineering approach using NaOH as a modulator along with a stabilization approach through the insertion of gallium ions into the MOF's nodes was used. Thus, different MOFs with varying compositions of Fe and Ga were synthesized, denoted as FexGay-MOF. Stability tests in water and oxidative environments (in the presence of H2O2) confirmed that the gallium-doped MOFs indeed exhibited greater stability and prevented the leaching of iron sites. This stability enhancement is attributed to the reduction in hydrogen peroxide decomposition, as Fe-MIL-88B exhibited high peroxidase activity and 91.4% iron leaching, while Ga-MIL-53 was unable to convert H2O2, and no gallium leaching was observed. Thus, Fe0.3Ga0.7-MOF demonstrated the highest stability in preliminary tests and was selected for further catalytic evaluations. Several parameters for the methane oxidation reaction, like temperature, pressure, solvent, catalyst mass, and others, were assessed. Reaction kinetics revealed that within 1 h, Fe0.3Ga0.7-MOF exhibited a productivity of 29.9, 236.7, and 28.5 μmol gcat-1 for methanol, formic acid, and acetic acid, respectively. The material demonstrated three cycles of reusability without loss of catalytic activity, showcasing the robustness of the catalyst and the employed stabilization method. Additionally, the hot filtration test confirmed the catalyst's entirely heterogeneous nature.
MEMBROS DA BANCA:
Presidente - Interno ao Programa - 1762430 - DALMO MANDELLI
Membro Titular - Examinador(a) Externo à Instituição - CAUE RIBEIRO DE OLIVEIRA - EMBRAPA
Membro Titular - Examinador(a) Externo à Instituição - MARCO ANDRÉ FRAGA - INT
Membro Suplente - Examinador(a) Interno ao Programa - 1601156 - WAGNER ALVES CARVALHO