Kinetics and FTIR characteristics of the pyrolysis process of poplar wood

The pyrolysis characteristics of residues of poplar (Populus sp.) wood were investigated using a thermogravimetric analyzer coupled with a Fourier transform infrared (TG-FTIR) spectrometer. The pyrolysis process was subdivided into four stages at a rate of 10°C·min−1, varying from 30 to 650°C. Below 180°C, a mass loss occurred for drying and preheating the sample and the onset temperature of pyrolysis ranged between 180–260°C. A significant mass loss of 61.4 wt.% occurred between 260–380°C, followed by a slow and continuous mass change with lignin devolatilization. The analysis of kinetic reactions showed that the activation energy (78.29 kJ·mol−1) in the low-temperature section was much larger than that (6.40 kJ·mol−1) in the high-temperature section. The evolved gases formed by thermal degradation of poplar wood were simultaneously analyzed by FTIR. It was observed from the main peaks that the emissions evolved during poplar wood pyrolysis were acetic acid, carbon dioxide, carbon monoxide, methane, water, some volatile compounds of esters, alcohols and aldehydes. The emissions gradually increased with rising temperatures before a strong peak around 360°C and then decreased. Most gaseous products were emitted in the 320–380°C range, while CO2 was continuously emitted in a wide range from 140–550°C.