Pyrolysis behaviors of rapeseed meal: products distribution and properties

Rapeseed meal (RM) is a solid waste for the production of rapeseed oil, which is a potential feedstock to produce fuels and carbon materials via thermochemical conversion. In this study, the pyrolysis behaviors of RM was investigated with the special attention paid to the properties of pyrolysis products. The results showed that temperature and residence time significantly affected the distribution of the products. From 350 to 650 degrees C, the increase of bio-oil yield during medium pyrolysis was the most significant (from 43.2% at 350 degrees C to 58.9% at 650 degrees C). However, the increase of gas yield in low pyrolysis was the most significant (from 4.0% at 350 degrees C to 14.5% at 650 degrees C). The organic components in RM were not as stable as that in biomass, the pyrolysis of which proceeded to almost completion at 500 degrees C. This led to the low heating value and energy density of the resulting biochar, while the biochar produced at lower temperature such as 350 degrees C was more suitable for the use as solid fuel. The benefit of the low thermal stability of the organics in RM was the lower content of tar in the bio-oil. Nevertheless, the abundant proteins in RM resulted in the bio-oil with a high content of nitrogen-containing organics (i.e., amides and pyrroles). The biochar also contained an appreciable amount of nitrogen that was thermally stable. In addition, the in situ-diffuse reflectance infrared Fourier transform spectroscopy characterization indicating the transformation of the functionalities during the aromatization of the organics in the biochar was conducted, providing information for tailoring functionalities of the biochar.

Automated summary

This study investigated the pyrolysis behavior of rapeseed meal (RM) and its properties of pyrolysis products. The results showed that temperature and residence time had a significant impact on product distribution. The low thermal stability of the organics in RM resulted in a low heating value and energy density of the resulting biochar. However, biochar produced at lower temperatures was more suitable for use as a solid fuel. The abundant proteins in RM led to a high content of nitrogen-containing organics in the bio-oil.