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Previous issue date: 2017-05-26 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Devido ?s exig?ncias ambientais e ao desenvolvimento da ind?stria qu?mica, a
demanda de hidrog?nio vem ganhando destaque importante nos setores energ?tico, de insumo
e ambiental. As duas principais rotas utilizadas na obten??o do hidrog?nio s?o as rea??es de
reforma a vapor e reforma a seco do metano. A maior dificuldade das rea??es de produ??o de
H2 ? encontrar catalisadores est?veis por longos per?odos, que sejam resistentes ao ac?mulo
de carbono e seletivos a forma??o do g?s hidrog?nio. Al?m de diminuir o custo do catalisador,
a utiliza??o de suportes catal?ticos influ?ncia positivamente nas rea??es de reforma,
aumentando a resist?ncia qu?mica e t?rmica durante os processos, al?m disso, proporciona boa
dispers?o da fase ativa, evitando sua sinteriza??o e, portanto, melhorando a atividade e
estabilidade do catalisador. Neste contexto este trabalho tem como objetivo, utilizar a
diatomita como suporte catal?tico para dispersar as fases met?licas de Ni e de Co, avaliando
os catalisadores obtidos para o processo de reforma a seco do metano, como tamb?m, avaliar
os efeitos da adi??o dos promotores de Ce ou La ao catalisador de melhor efici?ncia na rea??o
de reforma a seco do metano. Foram preparados catalisadores monomet?licos e bimet?licos de
Ni e Co, com diferentes concentra??es de fase ativa por impregna??o via ?mida. O suporte e
os catalisadores foram submetidos ?s seguintes caracteriza??es: difra??o de raios X (DRX),
adsor??o e dessor??o de N2, an?lise termogravim?trica (ATG), fluoresc?ncia de raios X
(FRX), redu??o ? temperatura programada (RTP) e microscopia eletr?nica de varredura
(MEV). Os testes catal?ticos foram realizados em um reator diferencial de leito fixo de
quartzo a 700?C. Os produtos formados durante a rea??o foram analisados por cromatografia
gasosa. Os resultados mostraram que foi poss?vel preparar os catalisadores mono e
bimet?licos de Ni e Co. O catalisador com composi??o de 8% de Ni e 2% de Co suportado
em diatomita apresentou uma boa intera??o com o suporte, menores perfis de temperatura de
redu??o e melhor estabilidade ao longo das 10h de ra??o. O catalisador contendo 10% de Ni
apresentou a maior atividade durante este per?odo. O uso dos promotores de Ce ou La n?o
alteraram as propriedades catal?ticas e levaram a uma maior forma??o de coque. Em todos os
casos estudados a diatomita se mostrou est?vel qu?mica e termicamente durante a prepara??o
dos catalisadores e o teste catal?tico, mostrando-se um excelente suporte para a rea??o de
reforma a seco do metano. / Due to environmental requirements and to the development of the chemical industry,
the demand for hydrogen has been getting an important focus in the energy, input and
environmental sectors. Since the two major methods used in obtaining hydrogen are steam
and dry methane reforming reactions. The greatest challenge faced by hydrogen production
reactions is to find long-term stable catalysts that are also resistant to carbon accumulation
and selective to the formation of hydrogen gas. Besides lowering the cost, the utilization of
catalytic supports has important role for the reforming reactions, increasing the chemical and
thermal resistance during the processes, besides, it provides good dispersion of the active
phase, avoiding avoiding the sinterization of the active phase, influencing positively the
activity and stability of the catalyst. In this context, this work aims to use diatomite as
catalytic support to disperse the metallic phases of Ni and Co, evaluating the catalysts
obtained for the methane dry reforming process, as well as evaluating the effects of addition
of Ce and La as promoters to the most effective catalysts. Monometallic and bimetallic Ni and
Co catalysts were prepared with different active phase concentrations using the wet
impregnation methodology. The support and the active phases were evaluated according to
the following characterization methods: X-ray diffraction (XRD), adsorption and desorption
of N2, thermogravimetric analysis (TGA), X-ray fluorescence (XRF), programmed reduction
temperature (TPR) and scanning electron microscopy (SEM). The catalytic tests were
performed in a quartz fixed bed differential reactor at 700?C. The products formed during a
reaction were analyzed by gas chromatography. The results showed that the mono and
bimetallic Ni and Co were formed. The catalyst with 8% of Ni and 2% of Co concentrations
supported on diatomite showed good interaction with the support, low reduction temperature
profile and and good stability over the 10h test. The catalyst containing 10% Ni had the
greatest activity during this reaction. The use Ce or O promoters had no influence to the
catalytic properties and led to a higher formation of coke. In all cases studied, the diatomite
was shown to be chemical and thermally stable during the preparation of the catalysts and the
catalytic test, being considered, therefore, an excellent support for the dry reforming reaction
of methane.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/23945 |
| Date | 26 May 2017 |
| Creators | Anjos, Gineide Concei??o dos |
| Contributors | 06117988320, http://lattes.cnpq.br/3318871716111536, Vitor Sobrinho, Eledir, 64656969915, http://lattes.cnpq.br/8488499388852606, Braga, Renata Martins, 05165674460, http://lattes.cnpq.br/4603529162393328, Barros, Joana Maria de Farias, 85239658404, http://lattes.cnpq.br/1016070459137884, Rabelo Neto, Raimundo Crisostomo, 61909378372, http://lattes.cnpq.br/8352049712728334, Melo, Dulce Maria de Ara?jo |
| Publisher | PROGRAMA DE P?S-GRADUA??O EM CI?NCIA E ENGENHARIA DE MATERIAIS, UFRN, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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