Investigation of kinetic decomposition characteristics of Malaysian wood species using Coats and Redfern (CR) method

Abstract

The mass loss against temperature and time through thermogravimetry analysis (TGA) was measured upon six wood species: Shorea laevis (Balau), Vatica rassak (Resak), Koompassia malaccensis (Kempas), Heritiera albiflora (Mengkulang), Shorea parvifolia (Meranti sarang punai), and Cratoxylum arborescens (Geronggang) at the heating rates of 5, 10, and 20 °C/min in a nitrogen environment. These species have shown three stages of thermal decomposition, including the dehydration stage, the active stage, and the passive stage. The thermal decomposition curves exposed that the hemicellulose and cellulose were actively pyrolyzed during the second-stage of the pyrolysis (active stage). In contrast, the decomposition of lignin happens at a slower pace in both the second and third-stage (passive stage). The maximum decomposition peak in the derivative thermogravimetric (DTG) curves for every species moved to a higher temperature range following the acceleration in heating rates. The kinetic decomposition parameters of the woods were identified by embracing the thermal kinetic method of Coats and Redfern (CR). The higher activation energy (E a ) in the second-stage demonstrates that the corresponding species consists of more cellulose compared to others. Furthermore, all species showed lower E a during the third-stage of pyrolysis involving lignin content. The pre-exponential factor (A) for all species disclosed a relative connection to the E a ; the higher the E a , the higher the value of A.