Síntese e caracterização de hidrotalcitas contendo V, Ti, W, Zr e Sn para reforma de etanol e hidrogenação do bagaço de cana.
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Data
2019-09-20
Autores
Siqueira, Marcos Rechi
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Os biocombustíveis são vistos como fontes sustentáveis para substituir os combustíveis fósseis, e o etanol é reconhecido como a principal alternativa. Uma maneira de aumentar a competitividade desse composto é o princípio de biorrefinaria, associando a produção de mais de um produto por processo. Os desafios estão associados ao desenvolvimento e desempenho de novos catalisadores capazes de produzir compostos de maior valor agregado. Os óxidos utilizados são derivados de HDLs e foram modificados com Cu, V, W, Ti, Sn e Zr. Os materiais foram caracterizados por diversas técnicas analíticas e, após a caracterização, foram empregados em reações em batelada a fim de converterem etanol em produtos de maior peso e valor. Em um segundo momento avalia’se a despolimerização da biomassa presente nas reações, e a metodologia de superfície de resposta para a maximização da reforma do etanol e dos produtos condensáveis. Por fim, um desses materiais sintetizados, foi testado em condições severas de tempo e temperatura a fim de avaliar os produtos formados e a robustez desse catalisador durante vários ciclos reacionais. Os produtos foram analisados por CG-FID e CG-MS e os resultados discutidos com base na literatura. A incorporação dos metais foi possível nas condições testadas e a modificação é capaz de apresentar um perfil diferente de conversão e reforma para cada metal modificador. Amaior conversão em produtos é do W-OMM (54,7%). Os produtos majoritários encontrados em todas as reações foram butanol e acetato de etila. A modificação com metais revela que a via de Guerbet ocorre e algumas rotas preferencias são dependentes do metal modificador. Nota-se a produção de compostos fenólicos a partir de um recurso renovável com alguns catalisadores. Quando a biomassa está presente na reação há modificçoes no perfil de conversão em gás e produtos. Foram verificados a presença de compostos fenólicos que não estavam presentes nas reações com ausência de biomassa, evidenciando a despolimerização da lignina. Os testes de otimização utilizando Cu-OMM conseguem dobrar a quantidade de etanol convertido (de 37,1 % a 79,6 %) e tal catalisador é ativo após quatro ciclos de reciclo, apresentando algumas modificações estruturais. Os materiais modificados com Cu ainda apresentaram um perfil de produção de benzeno e tolueno a partir de etanol com conversão de 8,6 % para benzeno e 38,4 % para tolueno nos melhores tempos de reação.
Biofuels are seen as sustainable sources to replace fossil fuels and ethanol is recognized as the main alternative. To increase the competitiveness of this compound is the biorefinery principle, associating the production of more product per process. The challenges are development and performance of new catalysts for production of higher value compounds. The oxides used are derived from HDLs and were modified with Cu, V, W, Ti, Sn and Zr. The materials were characterized by various techniques, and after characterization, they were employed in batch reactions to convert ethanol. Secondly, the depolymerization of the biomass present in the reactions and the response surface methodology for maximizing the reforming of ethanol and condensable products are evaluated. Finally, one of these synthesized materials was tested under severe time and temperature conditions to evaluate the products formed and the robustness of this catalyst during reaction cycles. The products were analyzed by CG-FID and CG-MS and the results discussed based on the literature. The incorporation of the metals is possible under the tested conditions and the modification is able to present a different conversion and reforming profile for each modifier metal. The largest conversion in products and the best oxide for conversion is W-OMM(54.7%), with Sn-OMM (10.4%) being the worst. The major products found in all reactions were butanol and ethyl acetate. Modification with metals reveals that the Guerbet pathway occurs and some preferred routes are dependent on the modifying material. Note the production of phenolic compounds from a renewable resource with some catalysts. When biomass is present in the reaction there are modifications in the conversion profile in gas and products. The presence of phenolic compounds that were not present in the reactions without biomass was verified, showing the lignin depolymerization. Optimization tests can double the amount of ethanol converted to Cu-OMM products (from 37.1% to 79.6%) and this catalyst is active after four recycling cycles with only a few structural modifications. The Cu modified materials also showed a benzene and toluene production profile from ethanol, with conversion of 8.6% to benzene and 38.4% to toluene at the best reaction times.
Biofuels are seen as sustainable sources to replace fossil fuels and ethanol is recognized as the main alternative. To increase the competitiveness of this compound is the biorefinery principle, associating the production of more product per process. The challenges are development and performance of new catalysts for production of higher value compounds. The oxides used are derived from HDLs and were modified with Cu, V, W, Ti, Sn and Zr. The materials were characterized by various techniques, and after characterization, they were employed in batch reactions to convert ethanol. Secondly, the depolymerization of the biomass present in the reactions and the response surface methodology for maximizing the reforming of ethanol and condensable products are evaluated. Finally, one of these synthesized materials was tested under severe time and temperature conditions to evaluate the products formed and the robustness of this catalyst during reaction cycles. The products were analyzed by CG-FID and CG-MS and the results discussed based on the literature. The incorporation of the metals is possible under the tested conditions and the modification is able to present a different conversion and reforming profile for each modifier metal. The largest conversion in products and the best oxide for conversion is W-OMM(54.7%), with Sn-OMM (10.4%) being the worst. The major products found in all reactions were butanol and ethyl acetate. Modification with metals reveals that the Guerbet pathway occurs and some preferred routes are dependent on the modifying material. Note the production of phenolic compounds from a renewable resource with some catalysts. When biomass is present in the reaction there are modifications in the conversion profile in gas and products. The presence of phenolic compounds that were not present in the reactions without biomass was verified, showing the lignin depolymerization. Optimization tests can double the amount of ethanol converted to Cu-OMM products (from 37.1% to 79.6%) and this catalyst is active after four recycling cycles with only a few structural modifications. The Cu modified materials also showed a benzene and toluene production profile from ethanol, with conversion of 8.6% to benzene and 38.4% to toluene at the best reaction times.
Descrição
Palavras-chave
Catálise heterogênea, Caracterização, Reação de Guerbet, Despolimerização da biomassa, Superfície de resposta, Heterogeneous catalysis, Characterization, Guerbet reaction, Biomass depolymerization, Surface response methodology