Pyrolysis of flaxseed residue: Exploration of characteristics of the biochar and bio-oil products

Abstract

In this study, the pyrolysis of flaxseed residue (FSR), a solid waste in the production of flaxseed oil, was carried out, aiming to understand the characteristics of the pyrolysis products. Comparing with traditional biomass (such as poplar wood), the organic components in FSR are easier to be cracked, producing the bio-oil with little heavy components. The high content of proteins in FSR made the resulting bio-oil nitrogen-rich. The resulting biochar contained abundant nitrogen, as some of the N-containing organics were thermally stable even at 650 °C. The significant cracking reactions made the biochar with the relatively lower carbon content, heating value and energy yield than that from biomass. The changes of functionalities of the biochar versus increasing temperature were also characterized with in situ diffuse reflectance infrared fourier transforms spectroscopy technique. The transformation of the carbonyl and other functionalities on surface of the biochar was sensitive to the change of temperature and the increase of temperature promoted the deoxygenation and aromatization reactions.