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Previous issue date: 2015-06-19 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / O Cerato de b?rio (BaCeO3) tem estrutura perovskita do tipo ABO3, na qual A e B
s?o c?tions met?licos. Estes materiais, dopados ou n?o, t?m sido estudados por apresentarem
caracter?sticas que os tornam promissores na aplica??o em c?lulas a combust?vel de ?xido
s?lido, permea??o de hidrog?nio e oxig?nio, como catalisadores, entre outros. Por?m, como os
materiais cer?micos de condutividade mista t?m sido produzidos por m?todos distintos de
s?ntese, algumas condi??es influenciam diretamente as propriedades finais, sendo uma das mais
importantes a dopagem do s?tio B, que pode ter influ?ncia direta no tamanho de cristalito, que
por sua vez pode influenciar a sua atividade catal?tica. No presente trabalho, perovskitas do tipo
(BaCexO3) tiveram o c?rio gradativamente substitu?do pelo praseod?mio para obten??o de
materiais tern?rios do tipo BaCexPr1-xO3 e bin?rios BaPrO3. Esses materiais foram sintetizados
pelo m?todo de complexa??o combinando EDTA-Citrato, sendo o material caracterizado via
DRX, MEV e BET para identifica??o da sua estrutura, morfologia e ?rea superficial. Al?m
disso foram realizados, em todos os materiais, testes catal?ticos em reator de leito fixo visando
a identifica??o daquele respons?vel pela convers?o total de CO em CO2 na menor temperatura
de opera??o, etapa que poder? ser utilizada como posterior ? produ??o de g?s de s?ntese
(CO+H2) a partir da oxida??o do metano. No presente trabalho a fase cristalina foi obtida
apresentando estrutura ortorr?mbica para todas as composi??es, com morfologia formada por
aglomerados de part?culas. O tamanho m?dio dos cristais variou entre 100 nm e 142,2 nm. As
?reas superficiais foram de 2,62 m?g-
1
para a composi??o BaCeO3, de 3,03 m?g-
1
para a
composi??o BaCe0,5Pr0,5O3 e de 2,37 m?g-
1
para a composi??o BaPrO3. Em rela??o aos testes
catal?ticos, pode-se concluir que a vaz?o ?tima de opera??o do reator foi de 50 ml/min e que a
composi??o que obteve a taxa m?xima de convers?o com a menor temperatura foi o BaCeO3,
para 400? C. Enquanto isso, observou-se que ao substituir parcialmente o c?rio pelo praseod?mio
houve uma diminui??o na atividade catal?tica do material. / Barium Cerate (BaCeO3) is perovskite type structure of ABO3, wherein A and B are metal
cations. These materials, or doped, have been studied by having characteristics that make them
promising for the application in fuel cells solid oxide, hydrogen and oxygen permeation, as
catalysts, etc .. However, as the ceramic materials mixed conductivity have been produced by
different synthesis methods, some conditions directly influence the final properties, one of the
most important doping Site B, which may have direct influence on the crystallite size, which in
turn directly influences their catalytic activity. In this study, perovskite-type (BaCexO3) had
cerium gradually replaced by praseodymium to obtain ternary type materials BaCexPr1-xO3 and
BaPrO3 binaries. These materials were synthesized by EDTA/Citrate complexing method and
the material characterized via XRD, SEM and BET for the identification of their structure,
morphology and surface area. Moreover were performed on all materials, catalytic test in a
fixed bed reactor for the identification of that person responsible for complete conversion of
CO to CO2 at low operating temperature, which step can be used as the subsequent production
of synthesis gas (CO + H2) from methane oxidation. In the present work the crystalline phase
having the orthorhombic structure was obtained for all compositions, with a morphology
consisting of agglomerated particles being more pronounced with increasing praseodymium in
the crystal structure. The average crystal size was between 100 nm and 142,2 nm. The surface
areas were 2,62 m?g-1
for the BaCeO3 composition, 3,03 m?g-1
to BaCe0,5Pr0,5O3 composition
and 2,37 m?g-1
to BaPrO3 composition. Regarding the catalytic tests, we can conclude that the
optimal flow reactor operation was 50 ml / min and the composition regarding the maximum
rate of conversion to the lowest temperature was BaCeO3 to 400? C. Meanwhile, there was
found that the partially replaced by praseodymium, cerium, there was a decrease in the catalytic
activity of the material.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/20229 |
| Date | 19 June 2015 |
| Creators | Lobato, Maxwell Ferreira |
| Contributors | 13681389420, http://lattes.cnpq.br/1030834608582624, Santos, Andarair Gomes dos, 02813010421, http://lattes.cnpq.br/3470634368296605, Moriyama, Andr? Lu?s Lopes, 06663278401, http://lattes.cnpq.br/5552878900145656, Lopes, Francisco Wendell Bezerra, 02485210470, http://lattes.cnpq.br/8791819081924591, Silva, Gilson Garcia da, 56634161453, http://lattes.cnpq.br/8681275097040450, Souza, Carlson Pereira de |
| Publisher | Universidade Federal do Rio Grande do Norte, PROGRAMA DE P?S-GRADUA??O EM ENGENHARIA QU?MICA, 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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