Híbridos ureasil-poliéter conjugados com zeólitas MFI para acetilação do glicerol
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Data
2019-07-04
Autores
Pereira, Elen Maria Feliciano
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Universidade Estadual Paulista (Unesp)
Resumo
Neste trabalho a metodologia sol-gel foi utilizada para a preparação de materiais híbridos orgânico-inorgânicos (HOI) à base de óxido de poli-etileno (PEO), ligado de forma covalente com o agente acoplador 3(isocianatopropil) – trietoxisilano (IsoTREOS) conjugados com um material zeolítico do tipo MFI, visando aplicações como catalisador para a reação de acetilação do glicerol e assim agregar valor a esse coproduto gerado na produção do biodiesel. O objetivo desta dissertação é demonstrar que o sinergismo entre híbridos do tipo siloxano-poliéter e as zeólitas pode ser explorado na produção de hidrogéis com atividade catalítica. As análises por Microscopia Eletrônica de Varredura (MEV) evidenciaram a homogeneidade na dispersão do material zeolítico na matriz híbrida Os difratogramas de raios-X apresentaram os picos característicos da estrutura cristalina da zeolita ZSM-5 após a conjugação com a matriz U-PEO. Os resultados de Calorimetria Diferencial de Varredura (DSC) revelaram que não ocorre uma mudança significativa na temperatura de transição vítrea (Tg), após a conjugação da matriz híbrida com a zeólita e revelaram uma diminuição do pico endotérmico associado à fusão dos domínios cristalinos do PEO1900, indicando uma possível interação matriz-zeólita. As análises por Espectroscopia no Infravermelho com Transformada de Fourier (FTIR) confirmaram a interação entre a matriz híbrida e a zeólita pelo deslocamento das bandas associadas ao oxigênio tipo éter não coordenado. Medidas de Espalhamento de Raios X a baixo Ângulo (SAXS) mostraram que os reagentes de partida na reação de produção do solketal foram rapidamente absorvidos pela matriz híbrida levando um deslocamento de qmáx de 2.37 para 1.31 nm-1 após 1 min de reação. As medidas da atividade catalítica frente à reação de acetilação do glicerol evidenciaram uma conversão de aproximadamente 40% após 10 min de reação e uma alta seletividade durante o processo catalítico. Os resultados demonstraram que a matriz híbrida conjugada com a zeólita mantém uma atividade catalítica comparável a da zeólita não conjugada.
In this work the sol-gel methodology was used for the preparation of organic-inorganic hybrid (HOI) materials based on polyethylene oxide (PEO) - covalently bonded with the coupling agent 3 (isocyanatopropyl) triethoxysilane (IsoTREOS) conjugate with a zeolitic material of the MFI type, aiming at applications as catalyst for glycerol acetylation reaction and thus add value to this byproduct generated in biodiesel production. The objective of this dissertation is to demonstrate that the synergism between siloxane-polyether hybrids and zeolites can be explored in the production of catalytic activity hydrogels. Scanning Electron Microscopy (SEM) analyzes showed homogeneity in the dispersion of zeolite material in the hybrid matrix. XDR patterns showed the characteristic peaks of the ZSM-5 zeolite crystal structure after conjugation with the U-PEO matrix. Differential Scanning Calorimetry (DSC) results revealed that no significant change in glass transition temperature (Tg) occurs after conjugation of hybrid matrix with zeolite and revealed a decrease in endothermic peak associated with fusion of crystalline domains of PEO1900. , indicating a possible matrix-zeolite interaction. Fourier Transform Infrared Spectroscopy (FTIR) analyzes confirmed the interaction between the hybrid matrix and zeolite by shifting the bands associated with uncoordinated ether oxygen. Small-angle X-ray Scattering (SAXS) measurements showed that the starting reagents in the solketal production reaction were rapidly absorbed by the hybrid matrix leading a qmax shift from 2.37 to 1.31 nm-1 after 1 min of reaction. Measurements of catalytic activity in the glycerol acetylation reaction showed approximately 40% conversion after 10 min of reaction and high selectivity during the catalytic process. The results showed that the zeolite-conjugated hybrid matrix maintains a catalytic activity comparable to that of unconjugated zeolite.
In this work the sol-gel methodology was used for the preparation of organic-inorganic hybrid (HOI) materials based on polyethylene oxide (PEO) - covalently bonded with the coupling agent 3 (isocyanatopropyl) triethoxysilane (IsoTREOS) conjugate with a zeolitic material of the MFI type, aiming at applications as catalyst for glycerol acetylation reaction and thus add value to this byproduct generated in biodiesel production. The objective of this dissertation is to demonstrate that the synergism between siloxane-polyether hybrids and zeolites can be explored in the production of catalytic activity hydrogels. Scanning Electron Microscopy (SEM) analyzes showed homogeneity in the dispersion of zeolite material in the hybrid matrix. XDR patterns showed the characteristic peaks of the ZSM-5 zeolite crystal structure after conjugation with the U-PEO matrix. Differential Scanning Calorimetry (DSC) results revealed that no significant change in glass transition temperature (Tg) occurs after conjugation of hybrid matrix with zeolite and revealed a decrease in endothermic peak associated with fusion of crystalline domains of PEO1900. , indicating a possible matrix-zeolite interaction. Fourier Transform Infrared Spectroscopy (FTIR) analyzes confirmed the interaction between the hybrid matrix and zeolite by shifting the bands associated with uncoordinated ether oxygen. Small-angle X-ray Scattering (SAXS) measurements showed that the starting reagents in the solketal production reaction were rapidly absorbed by the hybrid matrix leading a qmax shift from 2.37 to 1.31 nm-1 after 1 min of reaction. Measurements of catalytic activity in the glycerol acetylation reaction showed approximately 40% conversion after 10 min of reaction and high selectivity during the catalytic process. The results showed that the zeolite-conjugated hybrid matrix maintains a catalytic activity comparable to that of unconjugated zeolite.
Descrição
Palavras-chave
Glicerol, Zeólita, Híbridos orgânico-inorgânicos, Catálise heterogênea, Solketal, Glycerol, Zeolites, Organic-inorganic hybrids, Heterogeneous catalysis