A green biomass pretreatment using iron ion-catalyzed hydrogen peroxide for lignocellulose fermentation and biofuel production

The purpose of this work is to evaluate whether the iron ion-catalyzed hydrogen peroxide pretreatment (Fe-HP pretreatment) can be used as a more environmentally friendly pretreatment way for the fermentation of lignocellulose and the production of biofuel. The Fe-HP pretreatment significantly promoted the enzymatic hydrolysis/fermentation and the production of bio-jet fuels from sawdust (a typical lignocellulose biomass). Compared to the untreated sawdust, the Fe-HP pretreated sawdust showed higher sugar yield (33.8%, w/w) and higher ethanol yield (34.4%, w/w). Especially, the directional transformation of sawdust to bio-jet fuels was achieved by integrating biomass fermentation and catalytic synthesis processes. The highest ethanol conversion (94.2 C-mol %) and highest jet fuel selectivity (72.5 C-mol %) were obtained over the bi-functional catalyst (HSAPO34/NiHBET). The reactive oxygen species (ROS) in the Fe-HP pretreatment process was investigated by in-situ electron paramagnetic resonance analysis. Based on the biomass characterization, ROS analysis and intermediate analysis, the possible role and mechanism of the Fe-HP pretreatment were addressed. The iron ion catalyst can accelerate the decomposition of hydrogen peroxide to form hydroxyl radicals, and thus promoting biomass depolymerization and lignin removal (delignification of 28.9%, w/w) from lignocellulose. The Fe-HP pretreatment increased sugar yield and concentration during enzymatic hydrolysis, which was beneficial for ethanol fermentation and bio-jet fuel production.