The effect of feedstock composition and taxonomy on the products distribution from pyrolysis of nine herbaceous plants

Abstract

The effect of feedstock composition and taxonomy on the products distribution from pyrolysis of nine herbaceous plants was evaluated. Specifically, eight members of the Poaceae family and one member of the Fabaceae family were pyrolyzed in a fixed bed reactor to a final temperature of 700 °C. All samples resulted in a medium-energy CO2-rich gas and a phenol-rich liquid. The type of lignin rather than the overall lignin content was found to influence the phenols yield. All samples produced char with a suitable C/N ratio; eight plants produced char with high polarity; and only one sample (i.e., mountain brome) resulted in char with a sufficient aromaticity to be applied to soil. Low carbonization was associated with a high content of inorganic elements that were most likely deposited on the char's surface and blocked vaporization. The product distributions were dependent on (i) chemical and biochemical composition of feedstock, (ii) secondary reactions of liquid and char, and (iii) the samples' taxonomy. Red clover from the Fabaceae family was found to be the most distinct, followed by mountain brome from the Triticodae group (Poaceae family), and the remaining members of the Poodae group (Poaceae family). The least divergence was found between the hybrid samples.