Unraveling the synergistic development of carbon skeleton and pore networks involved in lignin pyrolysis.

To gain new insights into lignin pyrolysis, the synergistic development of carbon skeleton and pore networks in a wide temperature range of 200–800 °C was unraveled. The relative abundance of aromatic carbon structures increased exponentially with increasing temperature, as determined by 13C NMR deconvolution. Additionally, the g-factor type of radicals changed from O-centered (g-factor <2.0030) to C-centered (g-factor >2.0040) radicals. The evolution of the char macromolecules structure from disorder to order was principally characterized by a decrease in aromatic spacing (d 002 , 3.36→3.37 Å) an d an increase in stacking degree (L c , 7.89→8.67 Å) and aromaticity (f a , 75.19%→96.94%). f a h a s a strong negative linear correlation with d 002 (R 2 = 0.965). Ternary quadratic polynomials can relate specific surface area, total pore volume, and relative carbon content to the pore fractal dimension. The hypothesized chemical reaction networks and synergistic development of carbon skeleton and pore networks are essential for lignin effective valorization by a pyrolysis-based biorefinery strategies. [Display omitted] • The synergistic development of carbon skeleton and pore network was unraveled. • f a has a strong negative linear correlation with d 002. • Developed ternary quadratic polynomials link fractal dimension to SSA , TPV and C daf. • SSA and TPV were negatively correlated with d 002 , but positively correlated with f a. [ABSTRACT FROM AUTHOR]