Biofuels from waste biomass: a cascade strategy for the sustainable production of 2-methyl-tetrahydrofuran and 2-butanol

In recent years, the replacement of fossil resources with renewable ones has focused great interest, especially as regards the production of biofuels and valuable products. In particular, 2-methyl-tetrahydrofuran and 2-butanol are compounds of surplus value, which can be obtained from biomass. Both these molecules can be obtained from a series of hydrogenation-dehydration or decarboxylation-hydrogenation steps respectively of levulinic acid which is another promising platform chemical derived from biomass. Here, a cascade strategy for the production of 2-methyl-tetrahydrofuran and 2-butanol from waste biomass has been investigated, thus encouraging the valorization of waste biomasses into added-value bio-chemicals, instead of their traditional combustion for energy recovery or, even worse, of their landfill disposal. In this context, in the first step the acid-catalysed hydrothermal conversion of the exhausted cellulose powder, waste from the tissue paper production, into LA has been optimized under microwave irradiation. Then, in the subsequent step, the obtained biomass-derived levulinic acid-rich acid reaction aqueous slurry after neutralization was directly subjected to hydrogenation in the presence of commercial catalytic systems. Ru and Ru/Re catalysts were adopted and the selectivity of the process was significantly influenced by the reaction conditions. The optimization of both the reaction conditions and the composition of the catalytic system allows us to obtain different target products, such as 2-methyl-tetrahydrofuran and 2-butanol, opening the way to the direct production of biofuels from waste biomasses.