Monday, May 2, 2011
Grand Ballroom C-D, 2nd fl (Sheraton Seattle)
Recently developed iron co-catalyst enhancement of dilute-acid pretreatment of biomass is a promising approach to enhancing sugar release from recalcitrant lignocellulosic biomass. However, very little is known at present about the underlying mechanisms of the enhancements. In dilute-acid and ferrous iron co-catalyst pretreatments, we have observed concomitant increases in solubilized sugars in the hydrolysate and in reducing sugar ends in the biomass residue. We have also observed enhancements in sugar release during subsequent enzymatic saccharifications of iron co-catalyst pretreated biomass. FT Raman shows that modes representing the C-O-C, C-C and C-H bonds in cellulose are affected by iron co-catalyst pretreatment. Solid-state NMR spectra and imaging by bright-field and fluorescence light microscopy after Prussian blue staining, TEM and SEM collectively suggest that ferrous ions may also target other plant cell wall polymers, such as xylan and lignin, in parallel to action on cellulose. These results suggest that iron co-catalyst pretreatment may target multiple chemistries in plant cell wall polymer networks. A comprehensive understanding of the mechanisms of metal-enhanced pretreatment of biomass may lead to reduction in the cost of pretreatment.