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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Desenvolvimento de Peneiras Moleculares MCM-41 E Al-MCM-41, via processo hidrotermal assistido por micro-ondas. / Development of Molecular Sieves MCM-41 and Al-MCM-41, via microwave assisted hydrothermal process.

MEDEIROS, Cláudia Dourado. 30 April 2018 (has links)
Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-04-30T16:37:00Z No. of bitstreams: 1 CLÁUDIA DOURADO MEDEIROS - DISSERTAÇÃO PPGEQ 2014..pdf: 1542895 bytes, checksum: 5a74f0ba9e6514c2859c363f528e0b6f (MD5) / Made available in DSpace on 2018-04-30T16:37:00Z (GMT). No. of bitstreams: 1 CLÁUDIA DOURADO MEDEIROS - DISSERTAÇÃO PPGEQ 2014..pdf: 1542895 bytes, checksum: 5a74f0ba9e6514c2859c363f528e0b6f (MD5) Previous issue date: 2014-04-02 / Capes / As peneiras moleculares mesoporosas possuem um arranjo hexagonal de mesoporos com diâmetros de poros que variam de 2 a 10 nm, possuindo assim uma área superficial elevada. A adição de um metal a sua estrutura tem como função gerar a acidez ao material o tornando mais reativo, aumentado assim a possibilidade do seu uso como catalisador na indústria do petróleo. Atualmente, um dos problemas encontrados pelos pesquisadores para obtenção desse tipo de peneira, é o longo tempo de formação das estruturas. No presente trabalho as peneiras moleculares mesoporosas MCM-41 e Al-MCM-41 foram sintetizadas utilizando dois processos hidrotermais, a tradicional e por micro-ondas, com o objetivo principal de reduzir o tempo de síntese do material. A peneira molecular MCM-41 foi sintetizada utilizando o processo hidrotermal tradicional, 100 oC por 48 horas , como também utilizando o processo hidrotermal de micro-ondas através de três metodologias, adotando diferentes tempos e temperaturas. Tomando como base os resultados obtidos com as sínteses da peneira molecular MCM-41 por meio do método hidrotermal de micro-ondas, os mesmos métodos foram aplicados para a peneira molecular Al-MCM-41 nas mesmas condições de tempo e temperatura. Através dos difratogramas foi possível perceber que a estrutura hexagonal foi formada. Verificouse que o melhor tempo de síntese da Al-MCM-41 se deu com 60 minutos a 130 oC. A partir destes dados, foram realizadas novas sínteses, reduzindo o tempo gradativamente. Os resultados das análises de DRX, MEV e FTIR comprovam que as peneiras moleculares mesoporosas foram formadas, sendo possível identificar sua estrutura e morfologia. Os melhores resultados de síntese para as peneiras moleculares mesoporosas MCM-41 e Al-MCM-41, foram nos tempos 60 e 40 minutos e temperatura de 130 oC, respectivamente. / The mesoporous molecular sieves have a hexagonal arrangement of mesopores with pore diameters ranging from 2 to 10 nm, which implies in a high surface area. The addition of a metal into these structures has the function of generating acidity in the material making it more reactive, increasing the possibility of using it as a catalyst into the oil industry. Nowadays, one of the problems found by researches to obtain these type of molecular sieves is the long time of structure formation taken by these materials. In this study, the mesoporous molecular sieves MCM - 41 and Al -MCM -41 were synthesized using two traditional microwave, with the primary goal of reducing the time of synthesis of the material hydrothermal processes. The molecular sieve MCM -41 was synthesized using the traditional hydrothermal process 100 °C for 48 hours , as well as hydrothermal process using microwave by three methods , adopting different times and temperatures . Based on the results obtained with the synthesis of molecular sieve MCM -41 by hydrothermal microwave method, the same methods were applied to the molecular sieve Al -MCM -41 under the same conditions of time and temperature. Through the DRX patterns was observed that the hexagonal structure was formed. It was found that the best time of synthesis of Al- MCM-41 was given 60 minutes at 130 oC. From these data, new syntheses were carried out by reducing the time gradually. The results of DRX, MEV and FTIR show that the mesoporous molecular sieves were formed, it is possible to identify their structure and morphology. The best results for the synthesis of mesoporous molecular sieves MCM - 41 and Al -MCM -41, were at times 60 and 40 minutes and temperatures of 130 °C, respectively.

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