Effect of potassium on thermogravimetric behavior and co-pyrolytic kinetics of wood biomass and low density polyethylene

Abstract

The effect of potassium on the thermogravimetric behavior and co-pyrolytic kinetics of wood sawdust (WS) and low density polyethylene (LDPE) was investigated using a thermogravimetric analyzer. It was found that the co-pyrolysis behavior of the potassium-treated WS/LDPE mixtures were different from the combination of WS and LDPE, and the maximum weight loss between the experimental and calculated values (ΔW) was up to −24.2%. Potassium has a great influence on the pyrolysis of WS/LDPE mixtures, leading to the decrease of the characteristic decomposition temperature (TP1) and the increase of char yield with increasing potassium content. The simulation of possible structures indicates that [K-cellobiose]+ complexes have different configurations and potassium may facilitate the cracking of the glycosidic linkage and the ring-opening reaction. The kinetic analysis indicated that the co-pyrolysis of the potassium-treated WS/LDPE mixtures could be described by three independent first-order reactions. The increase of the potassium contents in the WS/LDPE mixtures causes an increase trend for E and A values in the first decomposition stage but leads to a decreasing trend in the second stage. Furthermore, the kinetic compensation effect (KCE) has been observed in each decomposition stage for the co-pyrolysis of potassium-treated WS/LDPE mixtures.