Influence of asphalt-derived volatiles on property of the biochar from pyrolysis of sawdust

Abstract

Inorganics are an important fraction of coal and they could involve the in co-pyrolysis of biomass and coal. In this study, to exclude interference of inorganics of coal and focus on exclusively the potential interaction of the volatiles from coal with that from biomass, the co-pyrolysis of asphalt and sawdust was conducted. The hydrocarbon radicals from asphalt could interact with the sawdust derived volatiles, diminishing the production of phenolics, aldehydes, ketones, etc. In addition, the hydrocarbon radicals themselves could deposit on the surface of the biochar and also reacted with the oxygen-containing organics, which increased the overall yield of biochar and promoted both the deoxygenation and carbonization reactions. This made the biochar from the co-pyrolysis carbon-rich and thermally more stable, which also enhanced the transition of amorphous carbon to graphite carbon on the surface of the biochar. In addition, the in-situ Diffuse Reflection Infrared Fourier Transform Spectra (DRIFTS) characterization indicated that the biochar from the co-pyrolysis at 450 °C featured with abundant aliphatic and aromatic hydrocarbon structures, while that from single sawdust pyrolysis consisted of abundant oxygen-containing functionalities such as ether bridge bonds, carbonyl, and carboxyl groups with low thermal stabilities.