Process synthesis for recovery of ionic liquid used in the pretreatment of biomass
quarta-feira, janeiro 30, 2019
Author: Vilas Boas, Lucas
Abstract: Researches on biofuels have been intensified once they represent a sustainable alternative to fossil fuels. In that class, the second-generation ethanol is considered an attractive option to compose the future energy matrix. For that reason, biomass pretreatment has been extensively studied as being one of the bottlenecks in the industrial-scale production of this biofuel. Among the several methods that can be applied to this stage, biomass dissolution in ionic liquids is an emerging and promising one. However, the high cost of these solvents is a factor that threatens industrial application.
For that reason, development and appraisal of processes to regenerate ionic liquids are essential for making this technology practicable. In this work, 4 different process flowsheets for recovery of 1-ethyl-3-methylimidazolium acetate employed in the pretreatment of sugarcane bagasse were studied. In the first flowsheet, a flash drum was used for separating the components of the mixture composed of ionic liquid and other solvents; in the second, a distillation column and a flash drum; In the third, a flash drum was used for recovering each solvent, with the exception of the ionic liquid, immediately after its utilization; In the last, a flash drum and a pervaporation unit, following the strategy of the former.
The energy demand and purity of the recovered solvent of each flowsheet were evaluated in order to define the most feasible one, by simulation in Aspen Plus. Physicochemical and thermodynamic properties necessary to define the ionic liquid and the biomass components in the simulation were extracted from, respectively, published works and the databank developed by NREL. The low biomass loading during pretreatment demands a large flow of solvent, about 40.20 kg of ionic liquid/kg of bagasse.
Global recoveries of 1-ethyl-3-methylimidazolium acetate achieved by the evaluated flowsheets were around 93 - 94%, the losses occur at filtration stages. Due to its lowest energy consumption, 42.6 MJ/kg dry biomass, the fourth flowsheet was found to be the most attractive one
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Page: Repositório Unicamp
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