Nearly 100% selective hydrolysis of pyrolytic sugar over sustainable carbon catalysts enables highly efficient production of bioethanol

The hydrolysis of levoglucosan (LG)–the major component of biomass pyrolysis oil–is the crucial step to bridge pyrolysis and fermentation. This study reports a series of sulfonated carbon catalysts (SCCs) as sustainable Brønsted acids for LG hydrolysis, which exhibit an excellent glucose selectivity over other hydration products (e.g., 5- hydroxymethylfurfural and light oxygenates). Notably, SCCs maintain a LG conversion rate of 95 % and a glucose yield of 90 % afterfour cycles of batch operations. Time-of-flight mass spectrometry and theoretical calculations further clarify the hydrolysis mechanism, as water-derived protons are activated by sulfonate groups of SCCs and hydrolyze LG through CO bond cleavage and hydration. Moreover, SCC-catalyzed hydrolysate is used in fermentation to produce bioethanol, enabling the maximal yield of ∼ 99 %, which is comparable to pure glucose commodity and much efficient than that from the aqueous acid hydrolysis. This study provides a sustainable alternative to mitigate the demand on heterogeneous catalysts for pyrolysis oil upgrading towards net-zero production of biofuels and biochemicals.