Estudo da reutilização do catalisador NbOPO4,nH2O na conversão do bagaço de cana-de-açúcar em furfural
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2022-06-06
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Universidade Federal de Viçosa
Resumo
O estudo do reuso do catalisador fosfato de nióbio (NbOPO 4 .nH 2 O, abreviado como NbP) na produção de furfural a partir do bagaço de cana-de-açúcar (BCA) em meio aquoso é o objetivo deste trabalho. O catalisador heterogêneo NbP foi explorado para hidrolisar a hemicelulose do BCA e desidratar seu principal carboidrato liberado, i.e., a xilose, em furfural. A relação biomassa / catalisador e o tempo de reação foram fixadas em 1/1 e 5 h. Duas temperaturas foram estudadas, i.e., 110 e 150 o C. Os compostos foram separados e quantificados por cromatografia líquida de alta eficiência (HPLC). Ao final de cada reação o catalisador foi separado da BCA por peneiração e tratado com (A) água, (B) 5 mL de acetona ou (C) calcinado a 500 ºC por 5h. Após o tratamento o catalisador foi reutilizado por mais um ciclo. Os licores do primeiro e segundo ciclos foram analisados usando o HPLC. O tratamento (A) foi escolhido pois apresentou rendimentos de furfural de 76 g kg -1 e recuperação de catalisador igual a 92 % em reações a 150 ºC. A fim de analisar a atividade do catalisador durante 4 ciclos de reuso e o impacto no rendimento de furfural, reações foram conduzidas em um reator de alta pressão a 150 ºC e 700 RPM. As massas de BCA e o volume de água foram ajustados a cada ciclo, com um rendimento de furfural igual a 73,63 g kg -1 para o último ciclo. Estes valores de rendimento foram consistes durante todos os ciclos de reuso. Em um último estudo, a reposição de catalisador foi realizada a cada ciclo mantendo a proporção de massa de NbP inicial constante nos ciclos, sem que fosse necessário um ajuste de BCA e o volume de água. Este estudo ldvou a rendimentos de furfural similares aos anteriores, 74,56 g kg -1 para o último ciclo, porém com melhore recuperação. A reposição do catalisador apresentou uma economia de 64,9% de NbP durante a execução das reações. Por fim, uma titulação potenciométrica com n-butilamina foi executada para determinar o potencial de NbP. Os resultados obtidos para o catalisador i) com o catalisador integro, ii) após reuso e iii) após reuso e com reposição foram respectivamente 406,0; 341,0 e 355,8 mV, indicando que não há diferença significativa de potencial e que o catalisador mantém suas propriedades ácidas mesmos após consecutivas reações de reuso. Palavras-Chave: Furfural. Cana-de-açúcar. Fosfato de Nióbio.
The study of the reuse of the niobium phosphate catalyst (NbOPO 4 .nH 2 O, abbreviated as NbP) in furfural production from sugarcane bagasse (BCA) in an aqueous medium is the objective of this work. The heterogeneous NbP catalyst was exploited to hydrolyze the BCA biopolymers and dehydrate the main released carbohydrate, i.e., xylose, into furfural. The biomass/catalyst ratio and reaction time were set at 1:1 and 5 h. The studied temperatures were 110 and 150 o C. The compounds were separated and quantified by high-performance liquid chromatography (HPLC). At the end of each reaction, the catalyst was separated from the BCA by sieving and treated with (A) water, (B) 5 mL of acetone, or (C) calcined at 500 °C for 5 h. After the treatment, the catalyst was reused for another cycle. The first and second cycle liquors were analyzed using HPLC. Treatment (A) was chosen because it presented furfural yields of 76 g kg -1 and catalyst recovery equal to 92 % in reactions at 150 ºC. In order to analyze the catalyst activity during 4 reuse cycles and the impact on furfural yield, reactions were carried out in a high-pressure reactor at 150 °C and 700 RPM. BCA masses and water volume were adjusted for each cycle, resulting in a furfural yield equal to 73.63 g kg -1 for the last cycle. These yield values remained consistent throughout all reuse cycles. In a previous study, the catalyst replacement was performed at each cycle, keeping the initial NbP mass ratio constant without adjusting BCA and the volume of water. This study yielded furfural yields similar to those obtained previously, 74.56 g kg -1 for the last cycle, but with better recovery values. This study showed a saving of 64.9% of NbP during the execution of the reactions. Finally, a potentiometric titration with n-butylamine was performed to determine the NbP potential. The results obtained i) with the intact catalyst, ii) after reuse, and iii) after reuse and with replacement were respectively 406.0; 341.0, and 355.8 mV. The results indicate no significant difference in potential and that the catalyst maintains its acidic properties even after consecutive reuse reactions. Keywords: Furfural. Sugar cane. Niobium phosphate.
The study of the reuse of the niobium phosphate catalyst (NbOPO 4 .nH 2 O, abbreviated as NbP) in furfural production from sugarcane bagasse (BCA) in an aqueous medium is the objective of this work. The heterogeneous NbP catalyst was exploited to hydrolyze the BCA biopolymers and dehydrate the main released carbohydrate, i.e., xylose, into furfural. The biomass/catalyst ratio and reaction time were set at 1:1 and 5 h. The studied temperatures were 110 and 150 o C. The compounds were separated and quantified by high-performance liquid chromatography (HPLC). At the end of each reaction, the catalyst was separated from the BCA by sieving and treated with (A) water, (B) 5 mL of acetone, or (C) calcined at 500 °C for 5 h. After the treatment, the catalyst was reused for another cycle. The first and second cycle liquors were analyzed using HPLC. Treatment (A) was chosen because it presented furfural yields of 76 g kg -1 and catalyst recovery equal to 92 % in reactions at 150 ºC. In order to analyze the catalyst activity during 4 reuse cycles and the impact on furfural yield, reactions were carried out in a high-pressure reactor at 150 °C and 700 RPM. BCA masses and water volume were adjusted for each cycle, resulting in a furfural yield equal to 73.63 g kg -1 for the last cycle. These yield values remained consistent throughout all reuse cycles. In a previous study, the catalyst replacement was performed at each cycle, keeping the initial NbP mass ratio constant without adjusting BCA and the volume of water. This study yielded furfural yields similar to those obtained previously, 74.56 g kg -1 for the last cycle, but with better recovery values. This study showed a saving of 64.9% of NbP during the execution of the reactions. Finally, a potentiometric titration with n-butylamine was performed to determine the NbP potential. The results obtained i) with the intact catalyst, ii) after reuse, and iii) after reuse and with replacement were respectively 406.0; 341.0, and 355.8 mV. The results indicate no significant difference in potential and that the catalyst maintains its acidic properties even after consecutive reuse reactions. Keywords: Furfural. Sugar cane. Niobium phosphate.
Descrição
Palavras-chave
Catálise, Furaldeído, Cana-de-açúcar, Fosfato de nióbio
Citação
ESPOSITO, Alexandra Jaques. Estudo da reutilização do catalisador NbOPO4,nH2O na conversão do bagaço de cana-de-açúcar em furfural. 2022. 53 f. Dissertação (Mestrado em Agroquímica) - Universidade Federal de Viçosa, Viçosa. 2022.