Comprehensive analysis of soybean residues pyrolysis products

Abstract

Pyrolysis has been applied to soybean residues from 400 °C to 600 °C to obtain value-added molecules. The biowaste has been previously physicochemically characterized and the temperature effect on products distribution has been evaluated. The results show that the liquid product (bio-oil) reached a maximum yield at 600 °C, while the solid product (bio-char) has a maximum performance at 400 °C. Among the desired products in bio-oil, aromatic hydrocarbons have been improved with the increment of temperature, with a maximum at 550 °C. For non-condensable products, CO2 was the highest emitted compound at all temperatures, together with CO as a consequence of cellulose and hemicellulose thermal decomposition. The minimal CH4 release is caused by the low biomass lignin content. In contrast to previous studies, the majority of the volatile organic compounds (VOCs) released during soybean residue thermal pyrolysis were identified for the first time. Aromatic hydrocarbons were predominant for every temperature, with methylbenzene as the major contributor. The largest relative proportion of aromatics was attained at 450 °C. 2-methylbutanal, 3-methylbutanal and 2-methylfuran were found in this phase as meaningful compounds. As for bio-char, it has shown a higher heating value of 5756 kcal/kg. In this way, it could be considered as a good alternative for power generation. Therefore, the great potential of soybean residue pyrolysis products requires an exhaustive analysis.