Roles of lignin in pore development during activation of peach wood

Cellulose, hemicellulose, and lignin are major components in typical woody biomasses. They have varied reaction networks in activation and thus contribute to pore development in different ways. Removal of one component might significantly affect pore characteristics of resulting activated carbon (AC). This was investigated herein by activation of peach wood (PW), delignified peach wood (DLPW), lignin, and a mixture of lignin/DLPW with K2C2O4 at 800 °C. The results disclosed that delignification increased abundance of aliphatic structures relatively and enhanced mass transfer of volatiles and permeability of K2C2O4 through creating voids. These features together intensified cracking reactions in activation of delignified PW, enhancing bio-oil yield (60.9 vs 56.1 % from PW), diminishing production of AC (17.4 vs 20.2 % from PW), promoting pore development (1218.5 versus 1099.4 m2g-1 from PW), enlarging pore size of micropores and creating more mesopores and macropores in AC. This rendered the AC of superior performance for adsorption of phenol. Co-activation of DLPW and lignin suggested that reactions between DLPW-derived volatiles and lignin-derived char formed carbonaceous deposits that filled pores of AC, diminishing overall specific surface area. The characterization of the activation process with in-situ IR technique indicated that more intensive cracking reactions in activation of DLPW even hindered aromatization but facilitated pore development.