Banca de DEFESA: CAMILA PACELLY BRANDÃO DE ARAÚJO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : CAMILA PACELLY BRANDÃO DE ARAÚJO
DATA : 07/12/2018
HORA: 08:00
LOCAL: SALA NUPEG
TÍTULO:

Molybdenum carbides and oxides with Co addition: evaluation of doping route effect and of kinetic parameters for the gas-solid reaction synthesis.

PALAVRAS-CHAVES:

molybdenum carbide, cobalt, doping, wet route, solid state, kinetics.

PÁGINAS: 90
GRANDE ÁREA: Engenharias
ÁREA: Engenharia Química
SUBÁREA: Tecnologia Química
ESPECIALIDADE: Cerâmica
RESUMO:

The development of new materials with improved properties is interesting for several industrial segments from the catalysis of chemical reactions for environmental legislation compliance, to the development of new electronic devices. Carbides and Mo oxides with cobalt addition may exhibit a diversity of intrinsic properties of great interest. In this work two methodologies for the addition of Co in these compounds with Mo (CoMoO₄ and Mo₂C-Co) were studied: solid and wet, having commercial molybdenum molybdate [(NH₄) ₆ [Mo₇O₂₄]4H₂O] and cobalt nitrate [Co(NO₃)₂.6H₂O] as the starting material. The doped precursors were characterized and the products of the thermal treatment (oxides) and the carbo-reduction reaction (carbides) were evaluated according to morphological (SEM), compositional (FRX) and crystallographic (XRD) aspects. It was verified that the dopant’s addition via solid state methodology presented itself, in both cases, as a more robust route; producing materials with smaller crystal sizes (~ 30nm to the carbide) and with higher dopant retention (δ ~ 10%) than the wet method (dp ~ 50nm and δ ~ 40%). A study of the conditions for obtaining Mo₂C with and without addition of dopant was performed using interval reactions. In the kinetic evaluation, Avrami’s nucleation and growth models were tested, as well as those proposed by Levenspiel of Shrinking Core. It was verified that the reaction proceeds according to MoO₂àMoà Mo₂C and that the model that best represents the actual behavior of the gas-solid reaction is that of Avrami with grain growth rate of M = 85.4 and dimensional parameter N = 0.34.

MEMBROS DA BANCA:
Interno - 2929066 - ANDRE LUIS LOPES MORIYAMA
Externo à Instituição - ARIADNE DE SOUZA SILVA - NENHUMA
Interno - 349801 - CARLSON PEREIRA DE SOUZA
Externo à Instituição - CLEONILSON MAFRA BARBOSA - IFRN
Externo à Instituição - GILSON GARCIA DA SILVA - IFRN
Externo ao Programa - 345842 - UILAME UMBELINO GOMES