The fuel properties and adsorption capacities of torrefied camellia shell obtained via different steam-torrefaction reactors

In this paper, three different steam-torrefaction reactors were employed to adjust the pyrolysis performance and adsorption capacities of biochar obtained from camellia shell (CS). The fuel performance of biochar was evaluated by heat value and component analysis. Meanwhile, the pyrolysis characteristics, mechanism of biochar and pyrolysis kinetics were investigated using thermogravimetric analysis (TGA), two-dimensional perturbation-based correlation infrared spectroscopy (2D-PCIS) analysis. The results showed that torrefied biochar obtained from atmospheric steam-torrefaction had the highest solid yield (88.4%), energy retention efficiency (ERE) (94.9%), methylene blue (99.63 mg/g) and heavy metals adsorption capacity which had exceeded that of commercial activated carbon. The pyrolysis kinetics results showed that the activation energy of hemicellulose significantly decreased with the increase of steam saturation. 2D-PCIS analysis indicated that the formation of pseudo-lignin was promoted with the torrefaction temperature based on the increased intensity of CC in aromatic skeleton. The element analysis and solid yield of biochar showed that the role of steam saturation was equal to the temperature on the torrefaction performance.