Lowering the pyrolysis temperature of lignocellulosic biomass by H2SO4 loading for enhancing the production of platform chemicals

Fast pyrolysis is a promising method for the production of liquid fuels and chemicals from lignocellulosic biomass. However, the catalytic effects of inherent alkali and alkaline earth metals and the high temperature used for the fast pyrolysis of biomass can drastically promote uncontrolled C-C/C-O bond cleavages and polycondensation reactions, resulting in the formation of considerable amounts of undesired light oxygenated organic compounds, permanent gases and char. Here, we demonstrate that H2SO4 loading can lower the pyrolysis temperature of biomass from 500 to 300 °C with higher yield of platform chemicals. The pyrolysis of H2SO4-loaded biomass at 300 °C is capable of selectively breaking C-O bonds in polysaccharides and effectively suppressing the formation of light oxygenated organic compounds, permanent gases and char. Approximately 50–60 wt% biomass feedstocks are primarily converted into anhydrosugars (mainly levoglucosan and xylosan) and their dehydrated products (mainly levoglucosenone and furfural). It is inferred that H2SO4 combined with the inherent alkali and alkaline earth metals (AAEM) in raw biomass can simultaneously inhibits the catalytic functions of AAEM and H2SO4 for achieving oriented conversion of hemicellulose and cellulose at low temperature. This study provides a very simple, atom-economical and energy-efficient pyrolytic strategy for enhancing the production of platform chemicals from biomass.