Effect of Torrefaction Temperature on Biomass Pyrolysis Using TGA and Py-GC/MS

Abstract—The effects of torrefaction on the pyrolysis of corn stalk were investigated using a thermogravimetric analyzer (TGA) and a pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). The results showed that with increasing torrefaction temperature, the volatile matter and oxygen content decreased, while the ash content and carbon content increased in torrefied corn stalk. The pyrolysis process of torrefied corn stalk can be divided into three stages. The first stage is from room temperature to 200°C, with little changes. The second stage occured between 200°C and 450°C. Because of the prior release of some volatile components by torrefaction, the total weight loss of torrefied corn stalk decreased with increasing torrefaction temperature. The third stage is the carbonization process above 450°C. With increased torrefaction temperature, the pyrolysis activation energy of corn stalk increases from 62.41 kJ/mol to 68.29 kJ/mol, and then decreases to 36.82 kJ/mol. Py-GC/MS analysis showed that the content of acetic acid in bio-oil reduced, while the content of many polycyclic aromatic compounds increased greatly, indicating that torrefaction could improve the quality of bio-oil. Keywords-Biomass; Torrefaction; Bio-oil; Py-GC/MS; Pyrolysi