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

Authors: Serapiglia, Michelle; Mullen, Charles; Boateng, Akwasi; CORTESE, LAURA - Rutgers University; BONOS, STACY - Rutgers University; HOFFMAN, LINDSEY - Rutgers University

Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/7/2015
Publication Date: 6/24/2015
Publication URL: http://handle.nal.usda.gov/10113/61015
Citation: Serapiglia, M., Mullen, C.A., Boateng, A.A., Cortese, L.M., Bonos, S.A., Hoffman, L. 2015. Evaluation of the impact of compositional differences in switchgrass genotypes on pyrolysis product yield. Industrial Crops and Products. 74:957-968.

Interpretive Summary: Switchgrass is a promising bioenergy crop within the United States for biofuels production. It can be converted to bio-oil through a thermochemical conversion process known as fast pyrolysis, the heating of organic matter in the absence of oxygen. During pyrolysis, differences in the composition of the switchgrass biomass can impact bio-oil production yield and quality. In order to understand how improvements in bio-oil quality can be achieved by the manipulation of biomass composition, variations in switchgrass biomass composition enabled by their genotype and cultivation were evaluated for their impacts on fast pyrolysis product yield. Nine genetically different individuals (genotypes) of switchgrass were grown on three field sites in New Jersey. We found that biomass composition was affected by both the genotype and the environment, along with an interaction between the two. The most significant impacts were from cellulose content and K content in the biomass. While the mineral content in the biomass was highly variable by environment and soil across the marginal sites examined, these differences in mineral content largely impacted product distribution of catalyzed pyrolysis and showed that lower mineral uptake in the biomass was beneficial for the production of aromatic hydrocarbon compounds in the bio-oil. The effects of both the switchgrass genotypes and the environment had on the pyrolysis products are useful in advising switchgrass breeders. These results demonstrate that improvements in pyrolysis product yield is conceivable but that growing conditions and soil conditions must also be taken into consideration.

Technical Abstract: As a dedicated bioenergy crop, switchgrass is a major feedstock within the United States for biofuels production and 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 impacts on fast pyrolysis product yield. Nine genotypes of switchgrass were grown on three marginal field sites throughout New Jersey. 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 by K. Mineral content in the biomass was highly variable by environment and soil variability across the marginal 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.