Variability in composition of individual botanical fractions of Miscanthus × giganteus and their blends

Abstract

Biorefineries require a consistent biomass feedstock to ensure optimal processing efficiency and a convenient method to evaluate biomass delivered at the factory gate. The combination of fractionation, selective blending of biomass streams, and densification is one strategy of ensuring feedstock with uniform quality attributes. In this study, dry mass fraction and compositional variability of botanical fractions of Miscanthus × giganteus harvested post-senescence were determined. Fourier transform near infrared (FT-NIR) spectroscopy was used to monitor composition of blends. Results showed that the majority of miscanthus stalks were composed of rind (48–63%) followed by sheath (17–28%), nodes (10–16%), and pith (8–13%). Rind had the highest glucan content (46.1%) while lignin content was highest in node (25.5%) and rind fractions (24.2%). Ash content was highest in blade fractions (8.9%) and was less than 1% in rind, pith, and nodes. Variability in composition was reflected in the 4250–4350 cm⁻¹ and 5500–6000 cm⁻¹ regions of the botanical fractions' FT-NIR spectra. Principal components analysis (PCA) of FT-NIR spectra of rind-blade blends were useful in screening blends based on structural carbohydrates, lignin and ash contents demonstrating the use of NIR spectroscopy in monitoring feedstock formulation.

Keywords:

• blending
• feedstock
• formulation
• near infrared spectroscopy
• principal components analysis

Acknowledgments

This work was partially funded by the Energy Biosciences Institutes (EBI) at the University of Illinois through the program titled, ‘Engineering Solutions for Biomass Feedstock Production’. The authors would like to thank Wei Liu and Tim Mies for their technical assistance.