Decomposition kinetic study, spectroscopic and pyrolytic analyses of Isoberlinia doka and Pinus ponderosa

Two woody species of different origins were subjected to Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis, and analytical pyrolysis gas chromatography/mass spectrometry (Py-GC/MS). Flynn-Wall-Ozawa, a model-free technique, was adopted for the decomposition kinetic study of Isoberlinia doka (ID) and Pinus ponderosa (PP). FTIR spectroscopy was employed to determine the level of cellulose crystallinity in the samples under investigation using the total crystallinity and lateral order indices methods. The apparent activation energy appeared as a function of conversion with significant influence from biomass diversity. The apparent activation energy recorded values of 202 to 365 kJ mol for ID and 205 to 583 kJ mol for PP. Thus, biomass decomposition kinetics is better modeled as a multi-step reaction mechanism. The analytical Py-GC/MS showed the presence of acids, sugars, and phenolic compounds in significant proportions for the two biomass samples. There were marked distinctions in both the quantity and the individual compounds detected in the biomass samples that were investigated.