Mechanocatalytic Synergy for Expedited Cellulosic Ethanol Production Compatible with Integrated Biorefinery

Abstract

Developing economically viable cellulosic ethanol process requires concentrated fermentable sugars and minimum water consumption. Biorefinery economics requires highly integrated efficiencies in the full utilization of all biomass components. Toward this objective, we have developed an enzyme-free mechanocatalytic saccharification process that combines mix-milling of P2O5 with lignocelluloses and successive hydrolysis into fermentable sugars. Demonstrated with corn stover (CS) and CS-xylose residues, after recovery of valuable hemicellulose, fermentable glucose in 75% yield at a high biomass loading (92 mg/mL) was obtained with concomitant precipitation of pristine lignin. The undetoxified concentrated hydrolysate allows for fermentative upgrading, achieving 42 g/L ethanol (a benchmark (40g/L) for an economically feasible bioethanol process) in 52 h after hemicellulose is converted into xylose. P2O5 is essential in fragmentation of cellulose in the milling stage and subsequent accelerated hydrolysis to glucose by in situ produced H3PO4. The mechanocatalytic saccharification of biomass involving P2O5 is compatible with xylose and lignin recovery and facilitates the integrated conversion of all three biomass fractions.

Engineered yeast tolerance enables efficient production from toxified lignocellulosic feedstocks

“…S6). This performance corresponded to theoretical conversion yields of 78 to 91% and were all obtained from a single strain derived from a historically underperforming laboratory lineage; yet, they exceeded currently published values of cellulosic ethanol produced from undetoxified industrial feedstocks ( 40 – 42 ). Thus, despite the compositional and pretreatment–by-product complexity across this diversity of material (e.g., miscanthus contains ferulic and p -coumaric acids derived from lignin degradation; table S3), the combination of GRE2 evol and alcohol protective adjustments exhibited robustness and sufficiency to efficiently ferment highly toxified genuine feedstocks.…”

Processes for the valorization of food and agricultural wastes to value-added products: recent practices and perspectives

“…Liu et al [76] designed a particular mechanocatalytic process to produce high-quality glucose with high sugar titer and high yield from agricultural cellulosic biomass. The process unites mix-milling of solid P 2 O 5 with corn stover or corn stover-xylose residues and successive saccharification ahead of which hemicellulose is recovered.…”

“…The mechanocatalytic process conducted by Liu et al [76] resulted in a high yield of fermentable sugars (app. 75%) with high concentrations up to 31 g/L with no use of organic solvents.…”

“…The sulfur-free lignin Fig. 2 The mechanocatalytic process for the production of high-quality glucose and ethanol introduced by Liu et al [76] was obtained from the hydrolysate with precipitation. Finally, with fed-batch fermentation of undetoxified concentrated hydrolysate, ethanol titer of over 42 g/L from corn stover-xylose residues was obtained.…”

“…Finally, with fed-batch fermentation of undetoxified concentrated hydrolysate, ethanol titer of over 42 g/L from corn stover-xylose residues was obtained. P 2 O 5 , added in Liu et al [76] during the mix-milling process, engenders decrystallization, and depolymerization of cellulose into oligosaccharides. H 3 PO 4 is generated in the process, which hydrolyzes oligosaccharides into glucose.…”