Banca de QUALIFICAÇÃO: RODOLFO LUIZ BEZERRA DE ARAUJO MEDEIROS

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : RODOLFO LUIZ BEZERRA DE ARAUJO MEDEIROS
DATA : 23/12/2017
HORA: 10:00
LOCAL: Auditório do LABTAM - NUPPRAR
TÍTULO:

One-pot Synthesis of Ni, Co and Fe based Catalysts by Microwave-assisted Combustion for H2 Production via Dry Reforming of CH4

PALAVRAS-CHAVES:

One-Pot Synthesis, Microwave, Mixture Design, Ni, Fe, Co, Methane Reforming and H2.

PÁGINAS: 86
GRANDE ÁREA: Engenharias
ÁREA: Engenharia de Materiais e Metalúrgica
RESUMO:

Catalysts based on Ni, Co and Fe supported in Al2O3 were prepared simply and quickly by the one-pot microwave-assisted combustion method, using nitrates as precursors and low fuel content (urea). The catalysts were calcined at 550 ° C for 3 h and characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR), N2 adsorption/desorption (BET-BJH), energy dispersive X-ray (EDX), scanning electron microscopy (SEM-EDX), transmission electron microscopy (TEM) and thermogravimetry (TG) with coupled Fourier Transform Infrared Spectrophotometry (FTIR). The reducibility under H2 atmosphere and the catalytic activity during the dry reforming reaction of the catalysts were investigated by in situ X-ray diffraction. The catalytic tests were performed at a temperature of 700 ºC (activation and reaction) using a space velocity of 72 Lh-1g-1 and a CH4/CO2 ratio of 1 for 20 h. The design of experiment was applied to study different formulations of the catalysts and to verify their effects on CH4 and CO2 stabilities and H2 yield. The results indicate that the active phases have particle sizes below 20 nm, high degree of reduction and specific surface area around 200 m²g-1. In the catalytic tests different behaviors were observed, being the bimetallic Ni-Fe catalysts more stable and active than the bimetallic Ni-Co catalysts, due to the higher formation of the NiFe alloy. The mathematical models with coefficients of explanation (R²) above 0.9942 were used to experimentally model and validate the applied methodology, from the preparation of the TA1 trimetallic catalyst (8.7%wt. Ni and 1.3%wt. Co and Fe). The characterization results and the catalytic test were consistent with the proposed design, validating experimentally the proposed statistical model. Finally, in the optimization stage, the TA1 catalyst was promoted with Ce and Mg and activated at 800 ºC, aiming to reduce the coke formation that caused the encapsulation of the active phase, observed in all the catalysts tested. The activity of the oxygen vacancies and the modification of the surface acidity by Ce and Mg, respectively, strongly influenced the performance of the TA1 catalyst, in which CH4 and CO2 stabilities were observed above 88%, whereas the catalysts without the promoters did not achieved 60% stability. Therefore, the materials prepared in this thesis have potential for applications in heterogeneous catalysis, since the proposed route is simple, fast and uses low fuel, producing nanoscale catalysts with high resistance to coke formation, high stability and high yield of H2, in addition to allowing the partial replacement of Ni by components of lower cost.

MEMBROS DA BANCA:
Presidente - 349770 - DULCE MARIA DE ARAUJO MELO
Externo à Instituição - RAIMUNDO CRISOSTOMO RABELO NETO - INT
Externo ao Programa - 1979301 - RENATA MARTINS BRAGA
Interno - 1308577 - SIBELE BERENICE CASTELLA PERGHER