Study on the pyrolysis properties of corn straw by TG–FTIR and TG–GC/MS

Abstract

Corn straw, an agricultural waste with huge yields, can be thermochemically treated to promote its comprehensive utilization. Compared with traditional methods, thermogravimetry coupled with Fourier transform infrared spectroscopy (TG–FTIR) and thermogravimetry coupled with gas chromatography–mass spectrometry (TG–GC/MS) can be used to analyze more clearly the pyrolysis of corn straw. In this study, the distributed activation energy model was used to analyze the pyrolysis kinetics in order to elucidate the pyrolysis process. The distributed activation energy of corn straw changed from 93.39 to 186.57 kJ mol−1 at the conversion rates from 0.1 to 0.9 with a high correlation coefficient. The evolution of volatile products from corn straw pyrolysis was discussed by TG–FTIR and TG–GC/MS. Results showed that CO2, CH4, CO, H2O, and carbonyls were produced below 337 °C and reached their peak values at the maximum mass loss rate of corn straw corresponding to the pyrolysis temperature of 337 °C. Carbonyl compounds were mainly composed of C4–C5, which come from the pyrolysis of cellulose and hemicellulose. At high pyrolysis temperatures, the organic species of furans, phenols, ketones, and aldehydes increased because of the fracture and isomerization of cellulose and hemicellulose. Meanwhile, Benzene and long-chain alkanes have been found due to the removal of oxygen-containing functional groups and the rupture of benzene ring in lignin structure.