Pore characteristics and fractal properties of biochar obtained from the pyrolysis of coarse wood in a fluidized-bed reactor

Abstract

Conversion of coarse wood into biochar is being considered as one of several waste disposal and energy recycling options. In this study, biochar was produced by coarse wood of Chinese fir from furniture factory in a fluidized-bed reactor under pyrolysis condition. Aided by a computed-tomography detection system, the pyrolysis process of the coarse wood was visible without destroying the solid sample. The resultant samples were characterized for pore structure property related to its potential use in adsorption. The results show that coarse samples with complete devolatilization have the well-developed pore structure. The maximum surface areas of the solid samples are 33.87 and 214.60 m2/g for coarse wood pyrolyzed at 500, and 700 °C, respectively. Most of the pores in the solid samples are mesopores with diameters between 2 and 10 nm. Fluidized-bed coarse wood pyrolysis significantly reduced the pyrolysis time compared with other sawdust pyrolysis methods. Fractal analysis yielded additional information on the roughness of the pore surfaces and the pore structures. The results indicated that the coarse wood has potential application in a fluidized-bed reactor to convert into high-quality biochar with higher efficiency.