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Abstract(s)
Este trabalho teve como objetivo, o estudo da influência de catalisadores com características ácidas e redox, no processo de desidratação/oxidação catalítica de metanol (MeOH), na obtenção de Dimetoximetano (DMM) e Dimetil Éter (DME). Para tal, foram sintetizados catalisadores com propriedades ácidas e redox (Molibdatos de Ferro) e apenas com propriedades ácidas (Montmorillonite), de forma a ser possível perceber a influência deste tipo de propriedades. De referir que os molibdatos de ferro foram sintetizados com diferentes razões Mo/Fe e com diferentes quantidades de material de suporte, SiO2.
Do ponto de vista dos catalisadores com propriedades ácidas, estes foram sintetizados recorrendo a diferentes ácidos orgânicos (H2SO4, HCl, HNO3, H3PO4) para fazer a permuta dos iões existentes na Montmorillonite.
Sintetizados estes compostos, estudou-se o comportamento de alguns parâmetros, como a temperatura de reação e o efeito da pressão parcial de MeOH na corrente de alimentação, de forma a ser possível perceber o seu efeito nos outputs do processo, ou seja, na conversão de MeOH (XMeOH), seletividade (Si) e rendimento (η).
Neste trabalho, os catalisadores foram ainda caracterizados por espectroscopia de infravermelho (FTIR) e por difração de raio-X (DRX).
Do ponto de vista de resultados, foi possível constatar que a temperatura reacional e a pressão parcial de MeOH têm um efeito fundamental na performance catalítica.
Os catalisadores com propriedades redox que melhores resultados exibiram foram os catalisadores de Mo/Fe=3,00 (50,0% SiO2), exibindo seletividades e rendimentos em DMM de 77,6% e 19,6% respetivamente.
Dos catalisadores acídicos, foi possível verificar que aquele que melhores resultados exibe é o catalisador de Montmorillonite dopado com H2SO4, exibindo seletividades e rendimentos de 98,5% e 69,2% respetivamente.
Abstract: This work had the main objective to study the influence of catalysts with acid and redox characteristics, in the catalytic process of dehydration/ oxidation of MeOH, to obtaining Dimethoxymethane (DMM) and Dimethyl Ether (DME). Thus, the catalysts were synthesized with acidic and redox properties (iron molybdates) and only with acidic properties (Montmorillonite) to be able to see the influence of these properties. The iron molybdates were synthesized with different ratios Mo/Fe and with different amounts of support material, SiO2. Concerning the catalyst with acid properties, these were synthesized using organic acids (H2SO4, HCl, HNO3, H3PO4) to exchange ions of the Montmorillonite. Synthesized these compounds, we also studied the behavior of reaction temperature and the effect of the partial pressure of MeOH in the feed stream, in order to be able realize its effect on outputs of the process, such as, MeOH conversion (XMeOH), selectivity (Si) and yield (η). The synthesized catalysts were characterized by infrared spectroscopy (FTIR) and x-ray diffraction (XRD) in order to be able to evaluate the composition of the catalysts before and after reaction. From the point of view of results, it was found that the reaction temperature and the partial pressure of MeOH have a fundamental effect on the catalytic performance. The best catalysts with redox properties were those which contains Mo / Fe = 3,00 (50,0% SiO2), with selectivity’s and yields in DMM of 77,6% and 19,6% respectively. The best catalyst with only acidic properties was Montmorillonite catalyst doped with H2SO4, with selectivity’s and yields in DME of 98,5% and 69,2% respectively
Abstract: This work had the main objective to study the influence of catalysts with acid and redox characteristics, in the catalytic process of dehydration/ oxidation of MeOH, to obtaining Dimethoxymethane (DMM) and Dimethyl Ether (DME). Thus, the catalysts were synthesized with acidic and redox properties (iron molybdates) and only with acidic properties (Montmorillonite) to be able to see the influence of these properties. The iron molybdates were synthesized with different ratios Mo/Fe and with different amounts of support material, SiO2. Concerning the catalyst with acid properties, these were synthesized using organic acids (H2SO4, HCl, HNO3, H3PO4) to exchange ions of the Montmorillonite. Synthesized these compounds, we also studied the behavior of reaction temperature and the effect of the partial pressure of MeOH in the feed stream, in order to be able realize its effect on outputs of the process, such as, MeOH conversion (XMeOH), selectivity (Si) and yield (η). The synthesized catalysts were characterized by infrared spectroscopy (FTIR) and x-ray diffraction (XRD) in order to be able to evaluate the composition of the catalysts before and after reaction. From the point of view of results, it was found that the reaction temperature and the partial pressure of MeOH have a fundamental effect on the catalytic performance. The best catalysts with redox properties were those which contains Mo / Fe = 3,00 (50,0% SiO2), with selectivity’s and yields in DMM of 77,6% and 19,6% respectively. The best catalyst with only acidic properties was Montmorillonite catalyst doped with H2SO4, with selectivity’s and yields in DME of 98,5% and 69,2% respectively
Description
Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Química e Biológica
Keywords
Características ácidas e redox Acidic and redox properties Desidratação/oxidação catalítica Catalytic dehydration/oxidation Dimetoximetano Dimethoxymethane Dimetil éter Dimethyl ether Molibdatos de ferro Iron molybdates Pressão parcial de MeOH Partial pressure of MeOH Seletividade selectivity Conversão Conversion Rendimento Yield Montmorillonite
Citation
RAFAEL, João Miguel Antunes Mestre - Desidratação/oxidação seletiva de metanol recorrendo a catalisadores heterogéneos para a obtenção de biocombustíveis (DME e DMM). Lisboa: Instituto Superior de Engenharia de Lisboa, 2015. Dissertação de mestrado.
Publisher
Instituto Superior de Engenharia de Lisboa