Insights on butyl levulinate bio-blendstock: From model sugars to paper mill waste cellulose as feedstocks for a sustainable catalytic butanolysis process

Butyl levulinate (BL) represents a novel diesel bio-blendstock and a versatile intermediate and solvent. The one-pot acid-catalyzed conversion of C6-feedstocks, employing n-butanol as the solvent/reagent, implies the upgrading of low-cost or, even better, waste biomasses for developing prompt process intensification. In this paper, the one-pot butanolysis process has been studied, moving from model glucose and microcrystalline cellulose to a waste cellulose feedstock deriving from a real papermaking process. The performances obtained with this waste biomass have been optimized, achieving BL yields up to 46 mol %, adopting a high-gravity approach, in the presence of diluted sulfuric acid as the catalyst. The optimization was carried out also in the perspective of minimizing the alcohol etherification to dibutyl ether, and the feedstock carbonization to char by-product, whose characterization was performed to identify its suitable applications. The combined production of both BL as a valuable bio-fuel and char as an exploitable carbonaceous bio-material can pave the way to the development of the one-pot butanolysis of real cellulosic or lignocellulosic biomasses in an environmentally sustainable and integrated perspective, in agreement with the principles of the circular bio-economy.