Thermogravimetric Analysis and Pyrolysis Kinetics of Malaysian Wood Species

Abstract

The mass loss of three wood species in Malaysia, Shorea laevis, Koompassia malaccensis, and Shorea parvifolia were measured against time and temperature at three different heating rates (5, 10 and 20 °C/min) in nitrogen environment, through thermogravimetry analysis (TGA) technique. This measurement revealed that the decomposition of these wood generally occurred in three stages, the dehydration stage, the active stage, and; the passive stage. The maximum decomposition peak in derivative thermogravimetric (DTG) analysis curve shifted towards higher temperature range with the expedition in heating rate. The kinetic decomposition parameters of the timbers were determined by adopting thermal kinetic method of Coats and Redfern. Principally, the density and moisture content of timber does not influence the kinetic parameters studied in this work. Overall, the thermal decomposition in the second-stage (active stage) was dominated by the hemicellulose and cellulose while the decomposition of lignin was apparent in the third-stage (passive stage) of pyrolysis. The higher activation energy in the second-stage indicates that more cellulose is contained in the sample. The activation energy of lignin is observed to be much lesser compared to the activation energy of the hemicellulose and cellulose for two species tested except for the Shorea parvifolia.