Pretreatments for the continuous production of pyrolytic sugar from lignocellulosic biomass

•Advances in production of pyrolytic sugars hampered by char agglomeration.•Metals that catalyze sugar decomposition also catalyze lignin depolymerization.•Ferrous sulfate both prevented sugar decomposition and agglomerate formation.•Volumetric sugar productivity was 400 times higher than for enzymatic hydrolysis.