Effects of chemical inhomogeneity on pyrolysis behaviors of corn stalk fractions

摘要

To explore the effects of chemical inhomogeneity on pyrolysis behavior of corn stalk fractions, the chemical components of stem bark, stem pith, leaf blade, ear husk and whole stalk were analyzed and their pyrolysis behaviors were studied by using the thermo-gravimetric analysis coupled with Fourier Transform Infrared Spectrometry (TGA-FTIR). Results indicated that the chemical components and pyrolysis behavior of different corn stalk fractions were significantly different from each other. The ear husk possessed the highest volatile content of 76 wt.% and the highest cellulose content of 42 wt.%, respectively. The stem pith had the highest hemicelluloses content of 25 wt.%, the least content for cellulose of 37 wt.% and lignin of 6.5 wt.%, respectively. Three stages of mass loss were observed during leaf blade pyrolysis, while four stages were observed for all the other fractions. Only the ear husk was degraded to form CH_4 in a temperature range from 120 ℃ to 230 ℃; and only the stem bark was degraded into a form of CO in a temperature range from 230 ℃ to 310 ℃. When the temperature was more than 310 ℃, all other fractions were degraded intensively. Compared with those of other three fractions, the ear husk and stem pith had the lowest activation energy at each stage during the pyrolysis process. Chemical inhomogeneity in different corn stalk fractions was the main reason for the different behaviors.