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To better understand the pyrolysis mechanism for further process optimization, the pyrolysis characteristics of corn stalk and its three major components (i.e. hemicellulose, cellulose and lignin) were investigated and compared by amplifying experiments in a tubular furnace at different temperatures (from 300 °C to 900 °C). The distributions of pyrolysis products (in terms of gas, tar and char), the influence of temperature, the impacts and contributions of each single component on the pristine biomass pyrolysis were discussed in depth. It was found that, for each sample pyrolysis, the pyrolysis temperature played a huge role on the yields and properties of different products. Optimal temperatures for maximum tar yield were found to be between 450 °C and 500 °C. The high temperature (>600 °C) was favorable to generate gas products, accompanied by a reduction of tar and char yields. Because of their unique chemical structures, profound differences about the characteristics of pyrolysis products from each component were drawn from the analysis results. Among the three components, hemicellulose produced the highest CO2 and H2 yields, cellulose owned the highest CO yield, while lignin generated significantly more CH4. As for tars, hemicellulose tar mainly contained ketones, acids and furans, cellulose tar displayed higher aldehydes and furans, lignin tar was dominated by monomeric phenols and 2,3-dihydro-benzofuran. In addition, the SEM images also revealed the marked differences in the surface morphology of the chars. |
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