| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 3.01 MB | Adobe PDF |
Abstract(s)
As culturas energéticas apresentam vantagens muito significativas ao nível agrícola, sendo já uma alternativa a outras fontes de biomassa, nomeadamente as culturas alimentares, para a produção de biocombustíveis sólidos. No entanto, há ainda diversas barreiras que limitam a sua utilização para a produção de combustíveis líquidos, nomeadamente a baixa digestibilidade da sua fração celulósica.
Neste trabalho avaliou-se a composição química de duas culturas energéticas tendo sido comparadas com outras fontes de biomassa, nomeadamente resíduos agroindustriais. A biomassa de Miscanthus e Faia, culturas energéticas passiveis de serem cultivadas em Portugal, foram estudadas em trabalhos posteriores com vista à sua valorização no âmbito do enquadramento da biorrefinaria, tendo-se desenvolvido dois processos de fracionamento, hidrólise ácida e autohidrólise.
O tratamento por hidrólise ácida permitiu a obtenção de elevados rendimentos em monossacáridos (tendo-se obtido hidrolisados com concentrações de açúcares superiores a 24 g/L) passíveis de conversão em biocombustíveis líquidos. A autohidrólise permitiu a recuperação da hemicelulose essencialmente na forma de oligossacáridos, compostos com potenciais efeitos pré-bióticos e que apresentam maior valor acrescentado, tendo-se atingido concentrações de 16 g/L.
Ambos os processos levaram ao aumento significativo da digestibilidade enzimática da fração celulósica remanescente de ambos os materiais testados, tendo-se atingido um máximo de aproximadamente, 70% em glucano e 80% em xilano para Miscanthus e aproximadamente 24% em glucano e 73% em xilano para a Faia, que contribui significativamente para o potencial de produção de biocombustíveis líquidos
A viabilidade técnico-económica da valorização destes materiais é apresentada e discutida tendo por base os balanços de massa preliminares, tendo-se demonstrado que os processos de autohidrólise apresentam maior potencialidade de viabilidade económica.
Energy crops have very significant advantages at the agricultural level, and are already an alternative to other sources of biomass, namely food crops, for the production of solid biofuels. However, there are still several barriers that limit their use for the production of liquid fuels, namely the low digestibility of its cellulosic fraction. In this work, the chemical composition of two energy crops was evaluated and compared with other sources of biomass, namely agro-industrial wastes. The biomass of Miscanthus and Beech, energy crops that can be grown in Portugal, were selected for further work aiming their valorization within the biorefinery, by studying two fractionation processes, acid hydrolysis and autohydrolysis. The treatment by acid hydrolysis allowed obtaining higher concentrations than 24 g/L in hemicellulosic monosaccharides, potentially convertible into liquid biofuels. Conversely, autohydrolysis allowed the recovery of hemicellulose essentially in the form of oligosaccharides, compounds with potential prebiotic effects and hence with higher added-value, where the values were higher than 16 g/L. Both processes led to a significant increase in enzymatic digestibility of the remaining cellulosic fraction of both tested materials, 70% of glucan and 80% of xilan, for Miscanthus and 24% of glucan and 73% of xilan, for Beech, which contributes grately to a potencial production of liquid biofuels. The techno-economic analysis of the proposed upgrading strategies is presented and discussed based on the preliminary mass and energy balances obtained. Autohydrolysis is shown to present potential economic advantages over the dilute acid hydrolysis process.
Energy crops have very significant advantages at the agricultural level, and are already an alternative to other sources of biomass, namely food crops, for the production of solid biofuels. However, there are still several barriers that limit their use for the production of liquid fuels, namely the low digestibility of its cellulosic fraction. In this work, the chemical composition of two energy crops was evaluated and compared with other sources of biomass, namely agro-industrial wastes. The biomass of Miscanthus and Beech, energy crops that can be grown in Portugal, were selected for further work aiming their valorization within the biorefinery, by studying two fractionation processes, acid hydrolysis and autohydrolysis. The treatment by acid hydrolysis allowed obtaining higher concentrations than 24 g/L in hemicellulosic monosaccharides, potentially convertible into liquid biofuels. Conversely, autohydrolysis allowed the recovery of hemicellulose essentially in the form of oligosaccharides, compounds with potential prebiotic effects and hence with higher added-value, where the values were higher than 16 g/L. Both processes led to a significant increase in enzymatic digestibility of the remaining cellulosic fraction of both tested materials, 70% of glucan and 80% of xilan, for Miscanthus and 24% of glucan and 73% of xilan, for Beech, which contributes grately to a potencial production of liquid biofuels. The techno-economic analysis of the proposed upgrading strategies is presented and discussed based on the preliminary mass and energy balances obtained. Autohydrolysis is shown to present potential economic advantages over the dilute acid hydrolysis process.
Description
Dissertação para a obtenção de grau de Mestre em Engenharia Química
e Biológica - Ramo de Processos Químicos
Keywords
Autohidrólise Biomassa Culturas energéticas Digestibilidade enzimática Faia Hidrólise ácida Miscanthus Acid hydrolysis Auto-hydrolysis Beech Biomass Energy crops Enzymatic digestibility
Citation
GOMES, Miguel Bruno Sousa Cerveira – Desenvolvimento de processos de desconstrução de biomassa de culturas energéticas selecionadas. Lisboa: Instituto Superior de Engenharia de Lisboa, 2021. Dissertação de Mestrado.
Publisher
Instituto Superior de Engenharia de Lisboa