How does the decomposition behavior of Klason lignin isolated from agricultural residues compare to that from wood?

The study compared the thermogravimetric behavior of Klason lignin isolated from beech wood and agricultural residues (olive pomace and wheat straw). The decomposition characteristics are influenced by the origin of the lignin, with differences observed in the active pyrolysis zone and peak rates.

Klason lignin from agricultural residues (olive pomace and wheat straw) shows wider zones of high devolatilization rates at lower temperatures compared to wood lignin. The peak rates for agricultural residues are attained at around 600–620 K, while hardwood lignin peaks at around 645 K and softwood lignin at around 680 K. The agricultural residue lignins also exhibit a shoulder zone at higher temperatures, indicating the decomposition of different lignin fragments. Despite these differences, a three-step kinetic model can describe the decomposition behavior of both wood and agricultural residue lignins, with similar activation energies and reaction orders.