Kinetics, comprehensive characteristics, and product analysis of peanut shell pyrolysis activated by a small amount of KCl

Abstract

Simultaneous conversion of peanut shell (PS) by pyrolysis into energy and useful chemicals is essential for its maximum utilization. The pyrolysis kinetics of PS and KCl-activated PS (KCl-PS) were studied using isoconversional and integral master plots methods. The power law (P4) model was found to be the most appropriate pyrolysis mechanism, and KCl-PS had a lower average activation energy than PS. When 1.56 wt% KCl was used to activate PS pyrolysis, enhanced gas products and bio-oil with lower oxygen content were produced, and the BET surface area of biochar increased significantly from 1.02 m2/g to 503.45 m2/g. This may be because potassium reacts with oxygen-containing functional groups to form K2CO3, which promotes the cracking of labile aliphatic compounds (e.g., CO, CH, C-O, and OH groups). The exploratory factor analysis extracting three factors also showed that compared with PS, KCl-PS scored higher on the pyrolysis factor of labile aliphatic compounds and the factor including temperature and residual mass, but lower on the factor describing energy change.