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Previous issue date: 2018-01-30 / O Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq / A assimila??o do modo como uma ze?lita ? formada partindo de um sistema amorfo e o controle sobre tamanho e morfologia dos produtos de s?ntese s?o aspectos fundamentais para a ?engenharia zeol?tica?. Um sistema para a s?ntese da ze?lita mordenita foi estudado, o qual possibilitou a obten??o de fase MOR sem indica??o da presen?a de qualquer outra fase. Foram realizadas varia??es nos par?metros: condi??o de tratamento t?rmico, temperatura, tempo, dilui??o do gel, teor e grau de pureza da ?gua, teor de s?dio, envelhecimento e tipo de s?lica, visando o estabelecimento da rela??o entre o tamanho e a morfologia dos produtos de s?ntese com as modifica??es efetuadas. A temperatura de cristaliza??o mostrou ser um fator primordial com rela??o ao tamanho de part?culas e cristalitos. A dilui??o do gel de s?ntese (50% m/m) proporcionou uma redu??o na agrega??o dos cristalitos e a varia??o do teor de ?gua na s?ntese implicou em mudan?as nas taxas de zeolitiza??o. O teor de s?dio modificou o crescimento dos cristais e o aumento de intercrescimentos e agrega??es de part?culas. Mudan?as na fonte de s?lica incrementaram a taxa de crescimento dos cristais e contribuiram para altera??es no tamanho dos mesmos. Cristais maiores foram obtidos a partir de sistemas com maior concentra??o de c?tions s?dio enquanto agregados de nanocristalitos. Agregados de pequenos cristalitos de mordenita pura de at? cerca de 50 nm foram obtidos com s?nteses realizadas a 150 ?C e com a dilui??o do gel j? preparado. Menores teores de s?dio e ?gua e o uso de fontes de s?lica de maior ?rea espec?fica (relativa a este tipo de material) tamb?m tendem ? resultar em menores cristalitos. Condi??es opostas viabilizaram o maior crescimento, gerando cristais de at? 1 ?m em m?dia. Os resultados mostraram que ? poss?vel exercer algum controle sobre o tamanho de part?cula e de cristalitos da ze?lita mordenita atrav?s do ajuste de par?metros inerentes ao sistema convencional de s?ntese. / The assimilation of the way a zeolite is formed from an amorphous system and the control over size and morphology of the synthesis products are fundamental aspects for "zeolitic engineering". A system for the synthesis of the mordenite zeolite was studied, which made it possible to obtain MOR phase without indicating the presence of any other phase. Variations were made in the parameters: thermal treatment condition, temperature, time, gel dilution, water content and degree of purity, sodium content, aging and type of silica, aiming to establish the relationship between product size and morphology with the modifications made. The crystallization temperature showed to be a prime factor with respect to particle size and crystallites. Dilution of the synthesis gel (50% w / w) provided a reduction in the crystallite aggregation and the variation of the water content in the synthesis implied changes in zeolitization rates. The sodium content modified the growth of the crystals and the increase of intergrowths and aggregations of particles. Changes in the silica source increased the growth rate of the crystals and contributed to changes in their size. Larger crystals were obtained from systems with higher concentrations of sodium cations as nanocrystallite aggregates. Aggregates of small pure mordenite crystallites of up to about 50 nm were obtained with syntheses performed at 150 ? C and with the dilution of the already prepared gel. Lower sodium and water content and the use of silica sources with a greater specific area (relative to this type of material) also tend to result in smaller crystallites. Opposite conditions enabled the highest growth, generating crystals up to 1 ?m on average. The results showed that it is possible to exert some control over the particle size and crystallites of the mordenite zeolite by adjusting parameters inherent to the conventional synthesis system.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/24827 |
| Date | 30 January 2018 |
| Creators | Lima, Rafael Chaves |
| Contributors | 50942611004, Ara?jo, Antonio Souza de, 35530502415, Loiola, Adonay Rodrigues, 88127370304, Bieseki, Lindiane, Pergher, Sibele Berenice Castella |
| Publisher | 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/masterThesis |
| 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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