Banca de QUALIFICAÇÃO: CAMILA PACELLY BRANDÃO DE ARAÚJO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : CAMILA PACELLY BRANDÃO DE ARAÚJO
DATA : 14/11/2018
HORA: 15:00
LOCAL: SALA NUPEG
TÍTULO:

Mo₂C-Co: Kinectic evaluation of the synthesis via gas solid reaction and doping route study

PALAVRAS-CHAVES:

molybdenum carbide, cobalt, doping, fixed bed reactor.

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

Sulfur compounds emissions have been, on the late years, subject to more severe environmental laws due to its impact on the environment (causing the acid rain phenomena) and on human health. It has also been object of much attention from the refiners worldwide due to its relationship with equipment’s life, which is decreased by corrosion, and also with products’ quality, as the later may have its color, smell and stability altered by the presence of such compounds. Sulfur removal can be carried out by hydrotreating (HDT) which is a catalytic process. Catalysts for HDS are traditionally based on Co(Ni)-Mo(W)/Al₂O₃. However, in face of the increased contaminants’ content on crude oil, and stricter legislation on emissions, the development of new, more active and efficient catalysts is pressing. Carbides of refractory material have been identified as potential materials for this use. The addition of a second metal to carbides may enhance catalytic activities by increasing the density of active sites. In the present thesis Mo₂C with Co addition was produced in a fixed bed reactor via gas-solid reaction of CH₄ (5%) and H₂(95%) with a precursor made of a mix of ammonium heptamolybdate [(NH₄)₆[Mo₇O₂₄].4H₂O] and cobalt nitrate[Co(NO₃)₂.6H₂O]  at stoichiometric amounts. Precursors’ where analyzed by XRF, XRD, SEM and TG/DTA. Carboreduction reactions were carried out at 700 and 750°C with two cobalt compositions (2,5 and 5%). Reaction’s products were characterized by XRF, XRD, SEM, TOC, BET and laser granulometry. It was possible to obtain Mo₂C with 2,5 and 5% cobalt addition as a single phase at 750°C with nanoscale crystallite sizes. At 700°C, however, both MoO₂ and Mo₂C phases were found by XRD. No Co containing phases were found by XRD. XRF, however, confirmed the intended Co content added. SEM images confirmed XRD data. The increase on Co content promoted a more severe agglomeration of the produced powder. The same effect was noted when the reaction temperature was increased. The powder synthesized at 750°C with 2,5% Co addition TOC analysis indicated the complete conversion from oxide material to carbide, with a 8,9% free carbon production. The powder produced at this temperature with 5% Co addition was only partially converted (86%).

MEMBROS DA BANCA:
Interno - 2929066 - ANDRE LUIS LOPES MORIYAMA
Interno - 349801 - CARLSON PEREIRA DE SOUZA
Externo à Instituição - CLEONILSON MAFRA BARBOSA - IFRN
Externo ao Programa - 350247 - JOAO FERNANDES DE SOUSA