Evaluation of the impact of compositional differences in switchgrass genotypes on pyrolysis product yield

Abstract

As a dedicated bioenergy crop, switchgrass is a potential feedstock within the United States for biofuels production. It can be converted to energy dense bio-oil through fast pyrolysis. Biomass compositional differences can influence the conversion efficiency and bio-oil product yield and quality. In order to understand how improvements in bio-oil quality can be achieved by manipulation of biomass composition, differences in switchgrass biomass composition were evaluated for their impacts on fast pyrolysis product yield. Nine genotypes of switchgrass were grown on one prime and two marginal sites in New Jersey. The results show that biomass composition was affected by genotype, the environment, and genotype× environment interactions. Non-catalytic pyrolysis product yields were largely affected by genotypic differences. The most significant impacts on non-catalytic pyrolysis products were from cellulose content and K content in the biomass. It was found that non-methoxylated phenolics were mainly produced from the breakdown of levoglucosan in the presence of K. Mineral content in the biomass was highly variable by environment and soil variability across the sites examined. These differences in mineral content largely impacted product distribution of HZSM-5-catalyzed pyrolysis, showing that lower mineral uptake in the biomass was beneficial for the production of aromatic hydrocarbons. Significant genotypic and environmental effects among the pyrolysis products demonstrate that breeding for improvements in pyrolysis product yield is conceivable but that growing conditions and soil conditions must also be taken into consideration.