Avaliação do catalisador CTA-MCM-41, modificado por poliacrilatos, na transesterificação de monoéster
Ano de defesa: | 2014 |
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Autor(a) principal: | |
Orientador(a): | |
Banca de defesa: | |
Tipo de documento: | Tese |
Tipo de acesso: | Acesso aberto |
Idioma: | por |
Instituição de defesa: |
Universidade Federal de São Carlos
|
Programa de Pós-Graduação: |
Programa de Pós-Graduação em Engenharia Química - PPGEQ
|
Departamento: |
Não Informado pela instituição
|
País: |
BR
|
Palavras-chave em Português: | |
Palavras-chave em Inglês: | |
Área do conhecimento CNPq: | |
Link de acesso: | https://repositorio.ufscar.br/handle/ufscar/3946 |
Resumo: | The silica hybrid CTA-MCM-41 (where CTA is the cetyltrimethylammonium cation) was synthesized and used in the transesterification of ethyl acetate with methanol. This is a model reaction used to test basic catalysts for the production of biodiesel from vegetable oils and fats. The basic sites in the catalyst consist of siloxy anions associated with CTA cations. In earlier work, it was found that progressive deactivation of the catalyst occurred when it was reused, due to leaching of the CTA cations located within the pores and on the external surface, resulting in partial loss of the basicity required for this type of reaction. The challenge of the present work was to stabilize the catalytic activity of CTA-MCM-41 by restricting the loss of cations from its interior (since the basicity derives from the interaction between the CTA cation and the siloxy anion). To this end, novel modifications were made to the synthesis of CTA-MCM-41, involving the encapsulation of acrylate monomers in the hydrophobic interior of the micelles followed by their subsequent polymerization using the application of ultraviolet irradiation together with a photoinitiator. The polymers formed then interacted with the hydrophobic tails of the micelles, which restricted the exit of CTA from the interior of the pores, hence improving the stability of the catalyst. The combination of the traditional synthesis method with polymerization using a microemulsion is innovative, because there are no reports in the literature that describe a synthesis in which the initial step is performed using emulsified polymers. The emulsions and the synthesized solids were evaluated using small angle X-ray scattering (SAXS). The materials were also analyzed by Xray diffraction, elemental (CHN) analysis, infrared absorption spectroscopy, scanning electron microscopy, and thermogravimetry. All these techniques helped to identify the presence of the monomer, as well as the polymer, in the channels of the CTA-MCM-41. It was confirmed that the presence of the polymer increased the catalytic stability of these new silica hybrids applied in the transesterification reaction. |
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Cruz, Fernanda TátiaCardoso, Dilsonhttp://lattes.cnpq.br/2462847535959232http://lattes.cnpq.br/96428349844736722016-06-02T19:55:39Z2014-06-272016-06-02T19:55:39Z2014-03-24CRUZ, Fernanda Tátia. Avaliação do catalisador CTA-MCM-41, modificado por poliacrilatos, na transesterificação de monoéster. 2014. 160 f. Tese (Doutorado em Ciências Exatas e da Terra) - Universidade Federal de São Carlos, São Carlos, 2014.https://repositorio.ufscar.br/handle/ufscar/3946The silica hybrid CTA-MCM-41 (where CTA is the cetyltrimethylammonium cation) was synthesized and used in the transesterification of ethyl acetate with methanol. This is a model reaction used to test basic catalysts for the production of biodiesel from vegetable oils and fats. The basic sites in the catalyst consist of siloxy anions associated with CTA cations. In earlier work, it was found that progressive deactivation of the catalyst occurred when it was reused, due to leaching of the CTA cations located within the pores and on the external surface, resulting in partial loss of the basicity required for this type of reaction. The challenge of the present work was to stabilize the catalytic activity of CTA-MCM-41 by restricting the loss of cations from its interior (since the basicity derives from the interaction between the CTA cation and the siloxy anion). To this end, novel modifications were made to the synthesis of CTA-MCM-41, involving the encapsulation of acrylate monomers in the hydrophobic interior of the micelles followed by their subsequent polymerization using the application of ultraviolet irradiation together with a photoinitiator. The polymers formed then interacted with the hydrophobic tails of the micelles, which restricted the exit of CTA from the interior of the pores, hence improving the stability of the catalyst. The combination of the traditional synthesis method with polymerization using a microemulsion is innovative, because there are no reports in the literature that describe a synthesis in which the initial step is performed using emulsified polymers. The emulsions and the synthesized solids were evaluated using small angle X-ray scattering (SAXS). The materials were also analyzed by Xray diffraction, elemental (CHN) analysis, infrared absorption spectroscopy, scanning electron microscopy, and thermogravimetry. All these techniques helped to identify the presence of the monomer, as well as the polymer, in the channels of the CTA-MCM-41. It was confirmed that the presence of the polymer increased the catalytic stability of these new silica hybrids applied in the transesterification reaction.A sílica híbrida CTA-MCM-41 (onde CTA é o cátion cetiltrimetilamônio) foi empregada, tal como sintetizada, na transesterificação do acetato de etila com metanol. Esta é uma reação modelo para testar catalisadores básicos para a produção de biodiesel a partir de óleos vegetais e gorduras. Os sítios básicos desse catalisador são identificados como sendo os ânions silóxi (≡SiO-) associados aos cátions CTA. Em trabalhos anteriores foi verificado que ocorre a desativação catalítica em seus sucessivos usos, ocasionados pela lixiviação dos cátions CTA localizados no interior dos poros e também na sua superfície externa. Desta forma, tem-se a perda de parte da basicidade requerida pela formação de grupos silanóis (SiOH) para este tipo de reação. Este trabalho teve como objetivo o desafio de estabilizar cataliticamente a CTA-MCM-41 dificultando a saída dos cátions do seu interior, pois, como já mencionado, a basicidade é promovida pela interação do cátion CTA com o ânion silóxi. Para isso, foram realizadas modificações inéditas na síntese da CTA-MCM-41 como o encapsulamento de monômeros acrílicos (metila, butila, octila e dodecila) no interior hidrofóbico das micelas e sua posterior polimerização sob a ação da radiação ultravioleta e de um fotoiniciador. Desse modo, os polímeros formados interagiram com as caudas hidrofóbicas das micelas, dificultando a saída do CTA do interior dos poros, por conseguinte proporcionando uma melhora na estabilidade catalítica. O método tradicional de síntese realizado juntamente com a polimerização em emulsão é inovador, pois ainda não há relatos na literatura cuja etapa inicial da síntese seja por meio de polímeros emulsificados. Assim, as emulsões e os sólidos sintetizados foram avaliados por meio da técnica de espalhamento de raios X a ângulos pequenos (SAXS). Os materiais foram analisados pelas técnicas de difratometria de raios X, análise química elementar (CHN), espectroscopia de absorção na região do infravermelho, microscopia eletrônica de varredura (MEV) e termogravimetria. Todas as técnicas auxiliaram para comprovar a presença do monômero e também do polímero nos canais da CTA-MCM-41. Desse modo, verificou-se que a presença do polímero melhorou a estabilidade catalítica destas novas sílicas híbridas sintetizadas e aplicadas na transesterificação.Financiadora de Estudos e Projetosapplication/pdfporUniversidade Federal de São CarlosPrograma de Pós-Graduação em Engenharia Química - PPGEQUFSCarBRCatáliseCTA-MCM-41PolimerizaçãoTransesterificaçãoBiodieselEstabilidade catalíticaBase catalysisCTA-MCM-41PolymerizationTransesterificationCatalytic stabilityBiodieselENGENHARIAS::ENGENHARIA QUIMICAAvaliação do catalisador CTA-MCM-41, modificado por poliacrilatos, na transesterificação de monoésterinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/doctoralThesisinfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFSCARinstname:Universidade Federal de São Carlos (UFSCAR)instacron:UFSCARORIGINAL5785.pdfapplication/pdf4761732https://{{ getenv "DSPACE_HOST" "repositorio.ufscar.br" }}/bitstream/ufscar/3946/1/5785.pdf604d605ce379585335d48545e6063093MD51TEXT5785.pdf.txt5785.pdf.txtExtracted texttext/plain0https://{{ getenv "DSPACE_HOST" "repositorio.ufscar.br" }}/bitstream/ufscar/3946/2/5785.pdf.txtd41d8cd98f00b204e9800998ecf8427eMD52THUMBNAIL5785.pdf.jpg5785.pdf.jpgIM Thumbnailimage/jpeg6946https://{{ getenv "DSPACE_HOST" "repositorio.ufscar.br" }}/bitstream/ufscar/3946/3/5785.pdf.jpg3e08928c568a736eb5a76afef3a42612MD53ufscar/39462019-09-11 04:12:38.136oai:repositorio.ufscar.br:ufscar/3946Repositório InstitucionalPUBhttps://repositorio.ufscar.br/oai/requestopendoar:43222023-05-25T12:47:59.407763Repositório Institucional da UFSCAR - Universidade Federal de São Carlos (UFSCAR)false |
dc.title.por.fl_str_mv |
Avaliação do catalisador CTA-MCM-41, modificado por poliacrilatos, na transesterificação de monoéster |
title |
Avaliação do catalisador CTA-MCM-41, modificado por poliacrilatos, na transesterificação de monoéster |
spellingShingle |
Avaliação do catalisador CTA-MCM-41, modificado por poliacrilatos, na transesterificação de monoéster Cruz, Fernanda Tátia Catálise CTA-MCM-41 Polimerização Transesterificação Biodiesel Estabilidade catalítica Base catalysis CTA-MCM-41 Polymerization Transesterification Catalytic stability Biodiesel ENGENHARIAS::ENGENHARIA QUIMICA |
title_short |
Avaliação do catalisador CTA-MCM-41, modificado por poliacrilatos, na transesterificação de monoéster |
title_full |
Avaliação do catalisador CTA-MCM-41, modificado por poliacrilatos, na transesterificação de monoéster |
title_fullStr |
Avaliação do catalisador CTA-MCM-41, modificado por poliacrilatos, na transesterificação de monoéster |
title_full_unstemmed |
Avaliação do catalisador CTA-MCM-41, modificado por poliacrilatos, na transesterificação de monoéster |
title_sort |
Avaliação do catalisador CTA-MCM-41, modificado por poliacrilatos, na transesterificação de monoéster |
author |
Cruz, Fernanda Tátia |
author_facet |
Cruz, Fernanda Tátia |
author_role |
author |
dc.contributor.authorlattes.por.fl_str_mv |
http://lattes.cnpq.br/9642834984473672 |
dc.contributor.author.fl_str_mv |
Cruz, Fernanda Tátia |
dc.contributor.advisor1.fl_str_mv |
Cardoso, Dilson |
dc.contributor.advisor1Lattes.fl_str_mv |
http://lattes.cnpq.br/2462847535959232 |
contributor_str_mv |
Cardoso, Dilson |
dc.subject.por.fl_str_mv |
Catálise CTA-MCM-41 Polimerização Transesterificação Biodiesel Estabilidade catalítica |
topic |
Catálise CTA-MCM-41 Polimerização Transesterificação Biodiesel Estabilidade catalítica Base catalysis CTA-MCM-41 Polymerization Transesterification Catalytic stability Biodiesel ENGENHARIAS::ENGENHARIA QUIMICA |
dc.subject.eng.fl_str_mv |
Base catalysis CTA-MCM-41 Polymerization Transesterification Catalytic stability Biodiesel |
dc.subject.cnpq.fl_str_mv |
ENGENHARIAS::ENGENHARIA QUIMICA |
description |
The silica hybrid CTA-MCM-41 (where CTA is the cetyltrimethylammonium cation) was synthesized and used in the transesterification of ethyl acetate with methanol. This is a model reaction used to test basic catalysts for the production of biodiesel from vegetable oils and fats. The basic sites in the catalyst consist of siloxy anions associated with CTA cations. In earlier work, it was found that progressive deactivation of the catalyst occurred when it was reused, due to leaching of the CTA cations located within the pores and on the external surface, resulting in partial loss of the basicity required for this type of reaction. The challenge of the present work was to stabilize the catalytic activity of CTA-MCM-41 by restricting the loss of cations from its interior (since the basicity derives from the interaction between the CTA cation and the siloxy anion). To this end, novel modifications were made to the synthesis of CTA-MCM-41, involving the encapsulation of acrylate monomers in the hydrophobic interior of the micelles followed by their subsequent polymerization using the application of ultraviolet irradiation together with a photoinitiator. The polymers formed then interacted with the hydrophobic tails of the micelles, which restricted the exit of CTA from the interior of the pores, hence improving the stability of the catalyst. The combination of the traditional synthesis method with polymerization using a microemulsion is innovative, because there are no reports in the literature that describe a synthesis in which the initial step is performed using emulsified polymers. The emulsions and the synthesized solids were evaluated using small angle X-ray scattering (SAXS). The materials were also analyzed by Xray diffraction, elemental (CHN) analysis, infrared absorption spectroscopy, scanning electron microscopy, and thermogravimetry. All these techniques helped to identify the presence of the monomer, as well as the polymer, in the channels of the CTA-MCM-41. It was confirmed that the presence of the polymer increased the catalytic stability of these new silica hybrids applied in the transesterification reaction. |
publishDate |
2014 |
dc.date.available.fl_str_mv |
2014-06-27 2016-06-02T19:55:39Z |
dc.date.issued.fl_str_mv |
2014-03-24 |
dc.date.accessioned.fl_str_mv |
2016-06-02T19:55:39Z |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/doctoralThesis |
format |
doctoralThesis |
status_str |
publishedVersion |
dc.identifier.citation.fl_str_mv |
CRUZ, Fernanda Tátia. Avaliação do catalisador CTA-MCM-41, modificado por poliacrilatos, na transesterificação de monoéster. 2014. 160 f. Tese (Doutorado em Ciências Exatas e da Terra) - Universidade Federal de São Carlos, São Carlos, 2014. |
dc.identifier.uri.fl_str_mv |
https://repositorio.ufscar.br/handle/ufscar/3946 |
identifier_str_mv |
CRUZ, Fernanda Tátia. Avaliação do catalisador CTA-MCM-41, modificado por poliacrilatos, na transesterificação de monoéster. 2014. 160 f. Tese (Doutorado em Ciências Exatas e da Terra) - Universidade Federal de São Carlos, São Carlos, 2014. |
url |
https://repositorio.ufscar.br/handle/ufscar/3946 |
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por |
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info:eu-repo/semantics/openAccess |
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openAccess |
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Universidade Federal de São Carlos |
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Programa de Pós-Graduação em Engenharia Química - PPGEQ |
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UFSCar |
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BR |
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Universidade Federal de São Carlos |
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