Banca de DEFESA: GILVAN PEREIRA DE FIGUEREDO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : GILVAN PEREIRA DE FIGUEREDO
DATA : 11/08/2017
HORA: 10:00
LOCAL: auditório do NUPPRAR
TÍTULO:

DEVELOPMENT OF CATALYTIC SUPPORTS AND APPLICATION OF LANTHANUM ALUMINATE FOR DRY REFORMING OF METHANE

PALAVRAS-CHAVES:

Gelatin method, Microwave synthesis, Catalytic supports, Dry reform, Hydrogen, Carbon nanotubes.

PÁGINAS: 27
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Físico-Química
ESPECIALIDADE: Cinética Química e Catálise
RESUMO:

Ceramic materials have several applications, mainly because of their versatility and properties. Several methodologies have been consolidated for the synthesis of these materials, but some disadvantages limit their applicability in catalysis. Thus, much research is concentrated on the study of catalyst and catalyst supports synthesis methods that are simple, fast, low cost, ecofriendly and produce suitable materials. In recent years, some alternative routes of synthesis have attracted a lot of attention, but obtaining the MgAl₂O₄ spinel by the gelatin method and perovskite LaAlO₃ via microwave assisted combustion reaction has been little explored. MgAl₂O₄ is widely used in the dry reforming of methane (DRM), but DRM studies using LaAlO₃ as support are very limited. Therefore, the aims of this work were: to synthesize MgAl₂O₄ using gelatin as an organic precursor; to prepare perovskite LaAlO₃ via microwave assisted combustion reaction; and to compare the performance of the dry reforming of methane from two nickel-based catalysts supported on LaAlO₃ and commercial α-Al₂O₃. By the gelatin method it was possible to obtain pure, nano-sized MgAl₂O₄ with crystallinity of up to 90.40%. An abrupt increase in crystallite size was observed for calcination temperature above 900 °C. In the synthesis by microwave, monophasic, nanometric and high crystallinity perovskite LaAlO₃ (77.51%) was obtained. The H₂ temperature-programmed reduction profiles (H₂-TPR) indicate that the oxygen vacancies present on the perovskite surface exerted a strong effect on the reduction temperature and reducibility of NiO nanoparticles, resulting in poor Ni⁰/LaAlO₃ interaction. The results of the short-term tests with gas hourly space velocity (GHSV) of 18 L g_-1 h_-1 show that the Ni/LaAlO₃ catalyst is 7.8 and 11.5% more stable than Ni/α-Al₂O₃ for CH₄ and CO₂ conversions, respectively. The Ni/LaAlO₃ great activity and stability are directly related to the presence of NiO (3.38% wt) after activation, which promoted the formation of carbon nanotubes (CNT), increasing the dispersion of the metal phase. Even under severe activation and reaction conditions (high GHSV), as in the long-term test, Ni/LaAlO₃ catalyst showed an H₂ yield of 37.2% more than Ni/α-Al₂O₃. Transmission electronic microscopy (TEM) analysis revealed that the Ni/α-Al₂O₃ catalyst presented deactivation problems associated with sintering effects. Thus, the properties of LaAlO₃ show a new path for the research of stable perovskites for catalysis and other industrial applications.

MEMBROS DA BANCA:
Presidente - 349770 - DULCE MARIA DE ARAUJO MELO
Externo à Instituição - EDISSON MORGADO JUNIOR - Cenpes
Externo à Instituição - LUIZ ANTÔNIO MAGALHÃES PONTES - UFBA
Externo ao Programa - 1979301 - RENATA MARTINS BRAGA
Interno - 2087667 - TIAGO PINHEIRO BRAGA