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S?ntese de ze?litas e argilas ?cidas pilarizadas a partir de mat?rias primas naturaisBieseki, Lindiane 20 July 2012 (has links)
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Previous issue date: 2012-07-20 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Structural changes in waste for zeolites synthesis are subject of many studies carried
out in the synthesis of molecular sieves. These materials are named molecular sieves because
they have well defined pore sizes and they have the capacity of select molecules by its size. In
this work, it was studied the synthesis processes of two types of molecular sieves: pillared
acid clays using as starting material one natural montmorillonite clay and the synthesis of
zeolites from a silico-aluminous residue. This residue is a byproduct of the extraction of
lithium -spodumene. The preparation of pillared acid clays was performed in two steps: 1?
acid treatment of clay samples (time and temperature studies) and 2?pilarization of them with
Al13 (Keggin ion). The temperature and acid concentration affect the removal of cations in the
structure and porosity of the material obtained. The analysis of X-ray diffraction (XRD) and
infrared spectroscopy (IR), showed that increasing the severity of the acid treatment
compromises the structural material. Also the pore size distribution is approximately uniform.
Despite presenting a structural disorganization, the samples were pillared. As evidenced by
XRD increasing the basal spacing, specific area and uniform porosity by adsorption of N2.
Regarding the microporous molecular sieves were synthesized zeolites A and NaP1 from a
silico-aluminous residue, a byproduct of extracting lithium. The temperature and time of
agitation during the synthesis were the most important factors for obtaining zeolite A. The
aging of the gel and the highest crystallization time promoted the formation of zeolite NaP1
using a Si / Al ratio = 3.2 / Modifica??es estruturais de res?duos para s?ntese de ze?litas ? tema de muitos estudos
desenvolvidos na ?rea de s?ntese de peneiras moleculares. Estes materiais s?o chamados de
peneiras moleculares por possu?rem tamanho de poros bem definido e por terem a capacidade
de selecionar as mol?culas pelo tamanho. Neste trabalho foram estudados os processos de
s?ntese de dois tipos de peneiras moleculares: argilas ?cidas pilarizadas, utilizando como
mat?ria prima natural uma argila montmorilonita, e tamb?m a s?ntese de ze?litas a partir de
um res?duo s?lico-aluminoso subproduto da extra??o de L?tio do -espodum?nio. A
prepara??o de argilas ?cidas pilarizadas foi realizada em duas etapas: 1? tratamento ?cido das
amostras de argila (estudos de tempo e temperatura) e 2? pilariza??o das mesmas com Al13
(?on de keggin). As vari?veis temperatura e concentra??o do ?cido influenciaram na retirada
de c?tions estruturais e na porosidade do material obtido. A partir das an?lises de difra??o de
raios-X (DRX) e espectroscopia de infravermelho (IV), observou-se que o aumento da
severidade do tratamento ?cido compromete a organiza??o estrutural do material. Tamb?m a
distribui??o no tamanho de poros fica menos uniforme. Mesmo apresentando menor
organiza??o estrutural, as amostras foram pilarizadas. Foi comprovado por DRX o aumento
do espa?amento basal e por adsor??o de N2 o aumento da ?rea espec?fica e uniformiza??o dos
poros. Com rela??o ?s peneiras moleculares microporosas, foram sintetizadas ze?litas A e
NaP1 a partir de um res?duo s?lico-aluminoso, subproduto da extra??o de L?tio. A temperatura
e o tempo de agita??o durante o processo de s?ntese s?o par?metros importantes para a
obten??o da ze?lita A. O envelhecimento do gel e o maior tempo de cristaliza??o promoveram
a forma??o da ze?lita NaP1, utilizando uma rela??o Si/Al = 3,2
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