Bioethanol production from different wood species pretreated with continuous steam explosion: Comparative study and impact of pretreatment severity
Abstract
Lignocellulosic biomass (LB) is a renewable feedstock which states as a promising alternative
to fossil resources to produce biomolecules, biomaterials, and energy through biorefinery processes.
However, the complex network formed by LB constituents leads to its recalcitrance and requires a
pretreatment step to ensure optimal biological conversion. Continuous steam explosion (CSE) induces
chemical and morphological alterations of LB fibers and allows deconstruction of lignocellulosic cell
walls to facilitate access to cellulose.
Three species of wood (oak, poplar, and spruce) were pretreated with pilot scale CSE at
different severities by varying temperature and residence time. Glucose release after enzymatic
hydrolysis and bioethanol production were monitored (Figure 1) and data we re modelled using an
experimental design approach to determine optimal CSE conditions and propose different scenarios.
Multimodal characterization of pretreated samples was also carried out to investigate the
impact of chemical and physical modifications o n 2G sugars release and on bioethanol production and
how they can help predicting LB reactivity for biological conversion. Some features such as particle
size, chemical composition, and lignin modifications were found to be related to bioethanol production
increase, while others such as crystallinity and hydrophobicity had a negative impact during enzymatic
saccharification. Depending on the wood species, specific band of infrared spectrum or fluorescence
intensity were found to be excellent proxies to pred ict saccharification rate and thus bioethanol
production.
Overall, our study demonstrates the importance of the choice of starting LB material and
pretreatment conditions to maximize bioethanol production and the necessity of performing a
multimodal approa ch to pinpoint the multiscale LB features having an impact on bioethanol
production.