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Previous issue date: 2013-12-16 / Ag?ncia Nacional do Petr?leo, G?s Natural e Biocombust?veis - ANP / Os materiais mesoporosos v?m tendo uma aten??o especial, dentre os quais foi descoberto no final da d?cada de 90 a peneira molecular mesoporosa do tipo SBA-15. As boas caracter?sticas do SBA-15 tornam este material muito promissor na ?rea de cat?lise, no entanto, devido ? aus?ncia de s?tios ativos nativos, ele apresenta baixa atividade catal?tica. Desta forma, diferentes metais e ?xidos v?m sendo inseridos nesta peneira molecular como meio de inserir s?tios ativos e elevar a sua atividade catal?tica. Dentre os ?xidos que vem sendo pesquisados, encontra-se o ?xido de ni?bio, que apresenta fortes s?tios ?cidos e tem em abund?ncia visto que o Brasil ? o maior produtor deste min?rio. Por outro lado a produ??o de biocombust?veis vem sendo almejada, sendo necess?rio o desenvolvimento de novos catalisadores para este fim. Desta forma, o objetivo deste trabalho foi desenvolver niobiosilicatos por um novo m?todo de s?ntese para aplica??o no craqueamento do ?leo de moringa. A metodologia consistiu em inserir o ?xido de ni?bio tanto pelo processo de p?s-s?ntese usando a impregna??o via ?mida ( porcentagens de 5, 15, 25 , 30 e 35%) e por inser??o direta. Para inser??o direta foi desenvolvido um novo m?todo de ajuste de pH, sendo testado diferentes pH ( 1.4, 1.6, 2.0 e 2.2) e diferentes raz?es de Si/Nb. Os materiais foram caracterizados por diferentes t?cnicas tais como: DRX, BET, MEV, EDX, UV-vis?vel, TG/DTG, DSC, MET , Acidez por n-bulitamina e FTIR. Posteriormente parte dos catalisadores desenvolvidos pelos dois m?todos foram testado no craqueamento termocatal?tico do ?leo de moringa, sendo usado um sistema simples de destila??o. Todos os niobiosilicatos obtidos apresentaram uma estrutura altamente ordenada, tendo altas ?reas espec?ficas, boa distribui??o de di?metros de poros, al?m de apresentar uma morfologia em forma de fibras. Nos catalisadores p?s s?ntese foi observado que o ni?bio inserido encontrava-se tanto tetraedricamente como octaedricamente coordenado, demonstrando que existiam tamb?m ?xidos formados na superf?cie externa do SBA-15, j? na s?ntese direta os materiais obtidos encontram-se apenas tetraedricamente coordenados. Dentre os pH testados o material que apresentou melhores caracter?sticas foi o sintetizado no pH 2.2. A aplica??o destes materiais no craqueamento catal?tico mostrou uma maior forma??o de l?quidos org?nicos ao serem comparados com o craqueamento t?rmico, al?m de diminuir significativamente a acidez e os res?duos formados, demonstrando que o uso do catalisador aumenta tanto a convers?o como a seletividade dos produtos. / The mesoporous materials has been an special attention, among them was discovered
in the 1990?s the mesoporous molecular sieve of SBA-15 type. The good features of the SBA-
15 makes this material very promising in catalysis, however, due to the absence of native
active sites, it has low catalytic activity. In this way, different metals and oxides have been
included in this molecular sieve as a means of introducing active sites and increase its
catalytic activity. Among the oxides that are being researched, there is the niobium oxide,
which presents strong acid sites and exists in abundance. Brazil is the largest producer of the
mineral. On the other hand, the production of biofuels has been desired, but it requires the
development of new catalysts for this purpose. The aim of this work was to develop silicate of
niobium by impregnation and by new synthesis method for application in the cracking of
moringa oil. The methodology consisted of inserting the niobium oxide either by postsynthesis
process using wet impregnation and direct insertion. For direct insert a new method
was developed for pH adjustment, being tested different pH, and the pH 2.2 was used
different ratios of Si/Nb. The materials were characterized by different techniques such as:
XRD, N2 adsorption, SEM, EDS, UV-visible, TG/DTG, DSC, TEM, acidity by
thermodesorption of n-butilamine and FTIR. After this part of the catalysts developed by the
two methods were tested in the thermocatalytic cracking of moringa oil, being used a simple
distillation. All silicates of Niobium obtained showed a highly ordered structure, having high
specific areas, good distribution of pore diameters, beyond present a morphology in the form
of fibers. In the catalysts after synthesis was observed that the niobium inserted has so as
octahedrally and tetrahedrally coordinated, demonstrating that there were also oxides formed
on the external surface of SBA-15. The materials obtained in the direct synthesis are only
tetrahedrally coordinated. The new synthesis method of pH adjusting by using the buffer
solution for it, proved to be very efficient for the production of such materials, because the
materials obtained showed characteristics and structures similar to the molecular sieve of
SBA-15 type. Among the pH tested the material that presented better characteristics was
synthesized at pH 2.2. The application of these materials in catalytic cracking showed a
higher formation of organic liquids when compared to thermal cracking, in addition to
significantly reducing the acidity and residues formed, demonstrating that the use of silicates
of Niobium increases both the conversion and the selectivity of the products.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/19371 |
| Date | 16 December 2013 |
| Creators | Santos, Anne Gabriella Dias |
| Contributors | 35530502415, http://lattes.cnpq.br/9770622597949866, Soares, Jo?o Maria, 67136958415, http://lattes.cnpq.br/2108722656012583, Pergher, Sibele Berenice Castell?, 50942611004, http://lattes.cnpq.br/5249001430287414, Quintella, Solange Assun??o, 32128088372, http://lattes.cnpq.br/7521511093074177, Souza, Luiz di, Ara?jo, Antonio Souza de |
| Publisher | Universidade Federal do Rio Grande do Norte, PROGRAMA DE P?S-GRADUA??O EM 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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