Environmental and economical issues linked to fossil resources (oil, gas, coal) production have driven research towards the utilization of renewable feedstocks for fuels and chemicals production. Lignocellulosic biomass is particularly interesting because this widespread feedstock does not threaten food supply.The study aims at converting lignocellulosic biomass into levulinic acid, a valuable building block which can lead to various products. This platform intermediate can be obtained by acid-catalyzed conversion of cellulose contained in raw biomass. However, the state of the art concerning this acid-catalyzed reaction revealed that the current conditions (diluted acids in harsh temperature conditions) result in numerous by-products formation. The selectivity issue often deals with process control, in particular with reaction time optimization.Our approach lies in using concentrated sulfuric acid as an alternative medium to catalyze cellulose conversion. Indeed, this strong acidic media is known to interact with hydrogen bonds in cellulose fibrils and favor cellulose decristallization. This property should promote the transformation of cellulose into levulinic acid at lower temperature thus limiting the formation of by-products.An extensive study on glucose and Avicel cellulose conversion in concentrated aqueous solutions of sulfuric acid was performed. Levulinic acid yields were determined by HPLC analysis and a special attention was dedicated to the identification and quantification of soluble or insoluble by-products, allowing the characterization of new species never described in aqueous solutions.A range of different acid concentrations and temperatures were screened in order to optimize the reaction. Catalytic results revealed good yields of levulinic acid (>50%) at 80 �C in 65 wt% sulfuric acid solutions. A discussion about the medium acidity and its influence on levulinic acid selectivity will be proposed and improvements yielding up to 70% levulinic acid will be presented.

Low temperature production of levulinic acid from cellulose using concentrated sulfuric acid solutions

248th National Meeting (2014)

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