Use of egg shells wastes for catalytic pyrolysis of lignocellulosic biomass

Catalytic pyrolysis of lignocellulosic biomass received considerable attention in the literature. Utilization of natural and waste materials as catalysts to improve the yields and quality of desired pyrolysis products is also an interesting option that deserves further investigation. In the present work Eggshell waste (EGW), a naturally calcium-rich material, is investigated as a catalyst for pyrolysis of two different (woody and a non-woody) Mediterranean biomass wastes: pine wood (PPC) and pomegranate peels (PGP). Slow pyrolysis was carried out at a constant temperature of 500 °C, 10 °C/min heating rate, and 60 min residence time with 250 mL/min N2 flow rate. The biomass samples were characterized in terms of proximate and ultimate analyses, mineral content, and high heating value (HHV). They were also analysed by FTIR spectroscopy, X-ray diffraction (XRD), and thermogravimetry. The bio-oils produced by pyrolysis of single fuels and mixtures with EGW (in the ratio 1:1) were characterized by GC-MS analysis and the quality in terms of chemical families was discussed. Results revealed that PPC bio-oil composition is dominated by oxygenated aromatics (~53 %), retene derivative, and anhydrosugars compounds, while, PGP oil mostly contained fine chemicals with oxygen, in particular furfural (~50 %) and anhydrosugars (~20 %). Co-pyrolysis results suggest that the alkali and alkaline-earth metals (AAEMs) present in the EGW affect pyrolysis oil composition, indeed, GC-MS confirmed that the addition of EGW increased the content of oxygenated aromatics and reduced the amount of anhydrosugar, retene derivative, and aliphatic compounds for PPC-EGW