The effect of feedstock densification on structural sugar release and yield in and biofuel feedstock and feedstock blends

In this work we examine the effect of a specific feedstock densification strategy (pelleting) on the release and yield of structural carbohydrates in a two-stage assay: dilute acid pretreatment (PT) followed by enzymatic hydrolysis (EH).

We used five feedstocks (2 corn stovers, miscanthus, switchgrass, poplar) and three feedstock blends. We first present experimental results over time to establish the robustness of the PT/EH assay, which limits the precision (and therefore the usefulness) of the assay. We then present the effect of variable PT reaction conditions on the conversion of a single feedstock (single-pass corn stover) in order to establish the range of reaction conditions likely to provide optimal conversion data. Finally, we apply the assay to the sixteen materials (8 feedstocks in 2 formats, loose and pelleted) over a more limited range of experimental conditions.

For the feedstock samples investigated in the laboratory-scale PT/EH assay described in this work, pelleting appears to have a slightly positive but not statistically significant effect on overall total sugar yield. Our data do not support the hypothesis that pelleting has a deleterious effect on the overall total sugar yield.