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Previous issue date: 2007-11-12 / Heterogeneous catalysts such as aluminophosphate and silicoaluminophosphate, molecular sieves with AEL of ALPO-11 and SAPO-11, were synthesized by the hydrothermal method with the following molar composition: 2.9 Al +3.2 P + 3.5 DIPA
+32.5 H20 (ALPO-11); 2.9 Al +3.2 P + 0.5 Si + 3.5 DIPA +32.5 H20 (SAPO-11) starting from silica (only in the SAPO-11), pseudoboehmite, orthophosphoric acid (85%) and water, in the presence of a di-isopropylamine organic template. The
crystallization process occurred when the reactive hydrogel was charged into a vessel and autoclaved at 170?C for a period of 48 hours under autogeneous pressure. The
obtained materials were washed, dried and calcined to remove the molecular sieves of DIPA. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectroscopy (FT-IR), thermo gravimetric differential thermal analysis (TG/DTA) and nitrogen adsorption (BET). The acidic properties were determined using adsorption of n-butylamine followed by programmed thermodessorption. This method revealed that ALPO-11 has weaker acid sites due to
structural defects, while SAPO-11 shows an acidity that ranges from weak to moderate.
However, a small quantity of strong acid sites could be detected there. The deactivation
of the catalysts was conducted by the cracking of the n-hexane in a fixed bed continuous
flow microrreator coupled on line to a gas chromatograph. The main products obtained
were: ethane, propane, isobutene, n-butane, n-pentane and isopentane. The Vyazovkin
(model-free) kinetics method was used to determine the regeneration and removal of the
organic template / Foram sintetizados catalisadores heterog?neos do tipo aluminofosfatos e silicoaluminofosfatos pelo m?todo hidrot?rmico a partir de alumina hidratada (pseudobohemita), ?cido fosf?rico 85%, s?lica gel, ?gua e diisopropilamina (DIPA)
usada como direcionador estrutural org?nico. Estes reagentes foram misturados a fim de obter g?is com as seguintes composi??es: 2.9 Al +3.2 P + 3.5 DIPA +32.5 H20; para
ALPO e 2.9 Al +3.2 P + 0.5 Si + 3.5 DIPA +32.5 H20 para SAPO. O processo de cristaliza??o ocorreu ? temperatura de 170 0C durante 48 h, quando foi poss?vel obter as fases puras para ALPO 11 e SAPO 11. Os materiais obtidos foram lavados com ?gua deionizada, secos e calcinados para remover as mol?culas do direcionador. Os materiais foram caracterizados por difra??o de raios-X (DRX), microscopia eletr?nica de varredura (MEV), espectroscopia de absor??o na regi?o do infravermelho (FTIR), an?lise t?rmica via TG/DTG e adsor??o de nitrog?nio (BET). As propriedades ?cidas
foram determinadas usando adsor??o de n-butilamina seguida de termodessor??o programada. Este m?todo revelou que o ALPO 11 possuem s?tios ?cidos fracos devido a defeitos estruturais, j? a amostra SAPO 11 apresenta uma acidez tipicamente fraca a moderada. Entretanto, uma pequena quantidade de s?tios ?cidos fortes foi detectada. A
desativa??o dos catalisadores foi conduzida pela rea??o de craqueamento do n-hexano em um microrreator catal?tico de leito fixo com fluxo cont?nuo acoplado em linha com
um cromat?grafo a g?s. Como principais produtos foram obtidos: etano, propano, isobutano, n-butano,e n-pentano, isopentano. Para determinar a regenera??o e a remo??o
do direcionador org?nico foi aplicado o m?todo cin?tico Vyazovkin (Model Free)
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/17595 |
| Date | 12 November 2007 |
| Creators | Silva, Arilson Jos? do Nascimento |
| Contributors | CPF:42314070453, http://lattes.cnpq.br/1595902438130772, Carvalho, Jos? Melo de, CPF:07124872472, http://lattes.cnpq.br/3824079454047896, Santos, I?da Maria Garcia dos, CPF:50548220115, http://lattes.cnpq.br/7060067415685353, Fernandes J?nior, Valter Jos? |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Qu?mica, UFRN, BR, F?sico-Qu?mica; Qu?mica |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| 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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