A comparison of dilute aqueous p-toluenesulfonic and sulfuric acid pretreatments and saccharification of corn stover at moderate temperatures and pressures

Single step pretreatment–saccharification of corn stover was investigated in aqueous p-toluenesulfonic and sulfuric acid media. Dilute aqueous solution of p-toluenesulfonic acid was a better catalyst than aqueous sulfuric acid of the same H+ ion concentration for single step pretreatment–saccharification of corn stover at moderate temperatures and pressures. For example, 100 mg corn stover heated at 150 °C for 1 h in 0.100 M H+ aqueous sulfuric acid produced 64 μmol of total reducing sugars (TRS), whereas the sample heated in 0.100 M H+p-toluenesulfonic acid produced 165 μmol of TRS under identical conditions. Glucose yield showed a similar trend, as aq. sulfuric acid and p-toluene sulfonic acid media produced 29 and 35 μmol of glucose respectively after 2.5 h. Higher catalytic activity of p-toluenesulfonic acid may be due to an interaction with biomass, supported by repulsion of hydrophobic tolyl group by the aqueous phase.

► Aqueous p-toluenesulfonic acid is better than H2SO4 for corn stover saccharification.
► Highest sugar yield is produced in aq. p-toluenesulfonic acid at 150 °C after 1 h.
► Pentoses and hexoses decompose differently in aq. p-toluenesulfonic acid and H2SO4.