Browsing by Author "Silva, Eduardo A.B."
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- An integrated process to produce vanillin and lignin-based polyurethanes from Kraft ligninPublication . Silva, Eduardo A.B.; Zabkova, Miriam; Araújo, José D.; Cateto, Carolina; Barreiro, M.F.; Belgacem, Mohamed Naceur; Rodrigues, AlírioThe aim of this manuscript is to present an integrated process that includes reaction and separation steps for producing vanillin and lignin-based polyurethanes from Kraft lignin. It provides details about lignin oxidation and subsequent vanillin recovery, as well as, the synthesis of lignin-based polyurethanes. The oxidation of Kraft lignin in alkaline medium has been carried out in a batch reactor and the optimum operational conditions for vanillin production obtained. The feasibility of a continuous process for vanillin production has been analyzed using a structured bubble column reactor. The generated reaction stream (degraded lignin and sodium vanillate) was further subjected to an ultrafiltration process to recover the vanillate. An ion-exchange process allows recovering the vanillin by passing the vanillate solution through a column packed with an ion-exchange resin in H+ form. The remaining lignin can act as a raw material to produce polyurethanes and/or biofuels. In this work the first approach was explored.
- Um processo integrado para produzir compostos fenólicos de elevado valor acrescentado a partir de lenhina KraftPublication . Silva, Eduardo A.B.; Zabkova, Miriam; Araújo, José D.; Cateto, Carolina; Barreiro, M.F.; Belgacem, Mohamed Naceur; Rodrigues, AlírioNeste trabalho, apresenta-se a estratégia que combina a engenharia de reacções e processos de separação para converter lenhina, obtida de licores processuais, em aldeídos de elevado valor acrescentado. O principal resultado é um processo integrado de produção de vanilina a partir de lenhina Kraft. O processo de integração é baseado em três etapas principais. A primeira etapa consiste na oxidação alcalina da lenhina em um reactor de borbulhamento com leito estruturado. Previamente, um extenso trabalho sobre a oxidação de lenhina em reator descontúnuo, incluindo a determinação das leis cinéticas de oxidação da lenhina e a optimização das condições de reação, foi realizado. Importantes informações para decidir sobre as melhores condições para a produção de vanilina foram publicadas. O projecto, a construção e a operação de um reator contínuo para a oxidação de lenhina foram executados. A produção de vanilina parece ser dependente das características estruturais da lenhina e limitada pela taxa de transferência de oxigênio para o líquido no reator. Considerando-se a etapa de recuperação da vanilina da solução oxidada, resultados importantes foram alcançados no âmbito do processo de ultrafiltração (UF), e estudos de adsorção de equilíbrio e cinética.
- Um processo integrado para produzir compostos fenólicos de elevado valor acrescentado a partir de Lenhina KraftPublication . Silva, Eduardo A.B.; Zabkova, Miriam; Araújo, José D.; Cateto, Carolina; Barreiro, M.F.; Belgacem, Mohamed Naceur; Rodrigues, AlírioThe implementation of biorefineries for the production of chemicals as well as materials and energy products is the key to ensure a sustainable future for the chemical and allied industries. LSRE has been working with lignin based bio-refining for near two decades with pioneering work on the subject. A Research & Development Program on the production of phenolic aldehydes, in particular vanillin, from Kraft lignin has been developed for many years. In this work, the strategy is to combine reaction engineering and separation processes for converting lignin from spent liquors into added-value aldehydes. The major result is an integrated process of vanillin production from Kraft lignin. The integrated process is based on three main steps. The first step consists on the alkaline lignin oxidation, in which valuable information can be found to decide the best conditions for the vanillin production. Considering the further isolation of vanillate from the oxidized solution, important results have been reached in the framework of ultra-filtration process, and equilibrium and kinetic adsorption studies. The degraded lignin resulting from membrane process can be considered for obtaining lignin-based polyurethanes materials.
- Valorisation of kraft lignin by using vanillin and lignin-based polyurethanes: Use of the biorefinery conceptPublication . Silva, Eduardo A.B.; Zabkova, Miriam; Araújo, José D.; Cateto, Carolina; Barreiro, M.F.; Belgacem, Mohamed Naceur; Rodrigues, AlírioIn kraft pulp mills, the capacity of the recovery boiler is very often a limiting factor to the increase of the pulp production. Until several decades ago, an upgrade to boiler system for dealing with higher quantities of black liquor was the only alternative. The possibility of lignin extraction from black liquor seems to be much more attractive, either for energy production or combustion elsewhere, or to serve as feedstock for chemicals production. Since the beginning of the 90’s, associate Laboratory LSRE/LCM has been focused on overcoming expansion limitations in pulp industries and, in this work, we show an alternative to this industry segment for the utilization of lignin and producing high added value chemicals from renewable biomass materials. Based on the biorefinery concepts, an integrated process for producing vanillin from kraft lignin oxidation has been proposed and each of the needed unit operations has been investigated to provide a deeper scientific understanding on this subject.