Fast pyrolysis of elephant grass: Intensification of levoglucosan yield and other value-added pyrolytic by-products

Abstract

The aim of this research is to intensify levoglucosan yield from elephant grass by fast pyrolysis and show the potential of elephant grass as a biomass to obtain other value-added byproducts. The biomass was subjected to acetic acid pretreatment at 90 °C prior to pyrolysis. The experiments were carried out in a GC/MS coupled with a pyroprobe reactor at 350–600 °C, resulting in more than 30 formed compounds including pyrolytic sugars, organic acids, ketones, aldehydes, furans, and phenolic compounds. The acid treatment contributed to hemicellulose and lignin reduction, of approximately 2 and 2.4 times, respectively. Consequently, the cellulose relative content in the biomass increased from 25.7% to 66.6%, contributing to an 11-fold increase in the levoglucosan content, compared to untreated biomass. Acid treatment prior to fast pyrolysis resulted essentially in the: a) removal of alkali and alkaline earth metals, confirmed by ICP, and b) biomass morphological changes confirmed by SEM, as well as probable chemical and structural changes suggested by FTIR qualitative analysis. In both cases, these results can explain levoglucosan yield increase and other changes in value-added byproduct formation observed after pyrolysis. In addition, the liquid fraction showed a reduction in the formation of oxygenated compounds, which are responsible for several undesirable properties of bio-oil as biofuel. Thus, the attained results can contribute to the development of the elephant grass agribusiness chain for energy purposes.