关键词: 果壳类生物质, 热解, 组分分析, 热重分析, 相关性分析

Abstract: [Objective] Nutshells are important forest biomass resources for energy in China. In order to provide theoretic supports for the thermal conversation and utilization of nutshells,the pyrolysis characteristics of nutshells and the correlations of cellulose,hemicellulose and lignin were investigated in this study.[Method]The cellulose, hemicellulose and lignin contents of seven kinds of nutshells, including Camellia shell, Coconut shell, Tung shell, Walnut shell, Chestnut shell, Pistachio shell and Cashew nut shell, were measured.Using the thermogravimetric analysis the correlations between pyrolysis peak temperature and the cellulose, hemicellulose and lignin content of nutshells were also analyzed.[Result]The major components of the six kinds of nutshell except Cashew nut shell are cellulose, lignin and hemicellulose, and the total content of these three components is more than 73%, while the total content of that in Cashew nut shell is only 47.41%. Several mass loss peaks are observed on temperature range from 200 to 410℃ during the whole pyrolysis process for six kinds of nutshells except Tung shell.Obviously pointed pyrolysis peaks on the left of the maximum pyrolysis peaks are appeared for Coconut shell, Camellia shell, Pistachio shell and Cashew nut shell, while for Walnut shell and Chesnut shell, acromion pyrolysis peaks on the left of the maximum pyrolysis peaks are found. The pyrolysis kinetic equations of all seven kinds of nutshells meet first-order kinetic equation, and the pyrolysis activation energy is ranged in 40-85 kJ·mol^-1. The correlation between the maximum pyrolysis peak temperature and the lignin content of nutshells is significantly positive (R=0.800, P=0.03 < 0.05), the correlation between the maximum pyrolysis peak temperature and the cellulose content of nutshells is weakly positive (R=0.446, P=0.32 > 0.05), and that between the maximum pyrolysis peak temperature and the hemicellulose content of nutshells is weakly positive too (R=0.509, P=0.24 > 0.05), however,the correlation between the maximum pyrolysis peak temperature and the total content of lignin and cellulose in nutshells is more significantly positive (R=0.899,P=0.005 < 0.05). The correlation between the left-side pyrolysis peak temperature and the hemicellulose content of nutshells except Tung shell is significantly positive (R=0.836, P=0.04 < 0.05), and that between the left-side pyrolysis peak temperature and the lignin content of nutshells is weakly positive (R=0.484, P=0.33 > 0.05), and that between the left-side pyrolysis peak temperature and the cellulose content of nutshells is weaker positive (R=0.295, P=0.57 > 0.05).[Conclusion] The pyrolysis characteristics of nutshells is influenced by the contents of cellulose, lignin and hemicellulose.The maximum pyrolysis peak temperature in the DTG curve of nutshells is mainly influenced by the lignin content, while the left-side pyrolysis peak temperature is mainly influenced by the hemicellulose content.

Key words: nutshell biomass, pyrolysis, composition analysis, thermogravimetric analysis, correlation analysis