Physico-chemistry of biochars produced through steam gasification and hydro-thermal gasification of canola hull and canola meal pellets

Abstract This research work was focused on the evaluation of chemical and physical properties for biochars obtained using hydro-thermal and steam gasification of biomass pellets produced from canola hull and canola meal. Van Krevelen plot showed the lignite-like characteristics for these biochars. For hydro-thermal gasification, X-ray diffraction, Raman, and thermogravimetric results showed incomplete depolymerization of cellulose structure of biomass at low temperatures. Thermogravimetric analysis and Raman analysis indicated complete destruction of cellulose structure and development of aromatic structure for temperatures ≥550 °C. For steam gasification, X-ray photoelectron spectroscopy C1s scan results showed the aromatic/aliphatic carbon contents of biochars larger than 69% for all gasification operating conditions. Biochars prepared using steam gasifictaion showed more cracked surface and larger porous characteristics compared to biochars prepared using hydro-thermal gasification. The development of aromatic structures in biochars was found in the case of all levels of operating conditions during steam gasification, and at high temperatures in the case of hydro-thermal gasification. The biochars produced by gasification showed the same O/C atomic ratio, larger H/C atomic ratio, lower compact aromatic structure development, and relatively higher ash content compared to the conventional biochars produced by pyrolysis.