Banca de QUALIFICAÇÃO: GILVAN PEREIRA DE FIGUEREDO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : GILVAN PEREIRA DE FIGUEREDO
DATA : 24/07/2017
HORA: 16:00
LOCAL: auditório do NUPPRAR
TÍTULO:

DEVELOPMENT OF CATALYTIC SUPPORTS FOR DRY REFORMING OF METHANE WITH NICKEL

PALAVRAS-CHAVES:

Gelatin method, Microwave synthesis, Catalytic supports, Dry reform, Hydrogen rich-gas, Carbon nanotubes

PÁGINAS: 62
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Físico-Química
ESPECIALIDADE: Cinética Química e Catálise
RESUMO:

Ceramic materials offer several possibilities of applications, mainly for their versatility and properties. Several methods have been consolidated for the synthesis of these materials, however numerous disadvantages limit their applicability in catalysis. Thus, many research focus on the synthesis of catalysts and catalysts supports through a simple, fast, low cost and ecofriendly method. Nowadays the synthesis by the methods of the gelatin and microwave assisted combustion has attracted great attention. Therefore, the first part of this work was the synthesis of the MgAl₂O₄ spinel and LaAlO₃ perovskite structures by the gelatin and microwave assisted combustion methods, since these routes are not reported or have been little explored in the synthesis of these materials. Stable perovskite LaAlO₃ has been well evaluated as catalytic support, however reports of dry reforming of methane using nickel as active metal and LaAlO₃ as support are very limited. Athwart the gelatin synthesis, a single phase MgAl₂O₄ spinel-type powders with a crystallinity of 39.18 - 90.40% and crystallite size in the range of 12.4 to 55.5 nm was obtained. The materials exhibited morphology in the form of plates and small agglomerates. It was found that increasing temperature and time of calcination favored the growth of crystallites and increased crystallinity. By the microwave combustion synthesis, a single phase LaAlO₃ perovskite-type with a crystallinity of 77.51% and crystallite size of 40.77 nm was obtained. The material revealed the presence of irregular dispersed agglomerates on the surface with morphology in the form of porous plates with appreciable amounts of voids. The performance for the dry reforming of methane of the Ni/LaAlO₃ catalyst was systematically compared with a traditional Ni/α-Al₂O₃ catalyst through activity tests (600-800 ° C) and short- and long-term stability tests (10 and 20 h) at 700 ° C under two GHSV of 18 and 72 L g^-1 h^-1, respectively. The TPR-H₂ profiles show that the oxygen vacancies present on the surface of the perovskite played a strong effect on the reduction temperature and the reducibility of NiO nanoparticles, resulting in poor Ni-support interaction. The results of the short-term GHSV tests 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 over CH₄ and CO₂ conversions, respectively. The higher Ni/LaAlO₃ stability and activity is 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, the Ni/LaAlO₃ catalyst showed an H₂ yield of 37.2% more than Ni/α-Al₂O₃. MET analysis revealed that the Ni/α-Al₂O₃ catalyst presented deactivation problems associated with the sintering effects. Thus, the properties of LaAlO₃ show a new path for the research of stable perovskites as candidates for DRM catalytic supports.

MEMBROS DA BANCA:
Presidente - 349770 - DULCE MARIA DE ARAUJO MELO
Externo ao Programa - 007.893.763-93 - JOSE ANTONIO BARROS LEAL REIS ALVES - UFCG
Externo ao Programa - 1979301 - RENATA MARTINS BRAGA