Pyrolysis kinetics of Hibiscus rosa sinensis and Nerium oleander

Pyrolysis is a thermal method in which volatile matter present in a biomass will be degraded to lower molecular substances. This study aims at evaluation of kinetics of lignocellulosic biomass of leaves and stems of Hibiscus rosa sinensis and Nerium oleander under pyrolytic conditions, their proximate and ultimate analyses and their calorific values. Pyrolysis experiments were carried out using a thermogravimetric balance, which combines heat flux type differential thermal analysis (DTA) with thermogravimetric analysis (TGA) at different heating rates under a nitrogen atmosphere. The results were analyzed using weight loss vs. temperature and derivative weight vs. temperature profiles obtained from DTA and TGA curves. Three kinetic stages apart from moisture evaporation were observed based on the type of biomass. Kinetic parameters such as the pre-exponential factor and activation energy for each degradation step were calculated using first-order kinetics. The assumption of first-order kinetics was also proved from the experimental data. The results showed that Nerium oleander leaves are more suitable for fuel production through pyrolysis due to their higher percentage of volatile matter, low sulfur content, lower ash content, higher calorific value and lower activation energy required to decompose constituents of biomass, namely hemicellulose, cellulose and lignin.