杉木间伐材炭化过程的FTIR光谱比较分析

Study on the charring process of Chinese fir thinning wood under different conditions by comparisons of FTIR

结合低温氮吸附等研究手段,对不同炭化工艺条件下杉木间伐材炭化物的FTIR光谱进行比较分析,研究了炭化物的微观结构随温度的变化规律以及炭化工艺对炭化物微观结构及其表面—OH的影响。结果表明,600～700℃,炭化物的碳网构造开始迅速发达,形成较大的网格;700℃为炭化物芳构化程度迅速提高的转折性温度;700～900℃,碳网进一步增大,形成红外吸收活性极低的大碳网。以N2为氛围气时,加盖法的炭化物碳网更大,比表面积较低;未加盖法和二步法的碳网相对较小,比表面积较大。在实验的基础上研究了炭化物的芳环振动吸收波数随温度变化的规律及机理,发现随温度升高,碳网增大的同时畸变越来越严重,炭化温度在700～800℃时,碳网在弱连接部位产生断键而趋向恢复平面结构。碳网畸变程度最大时所对应的环振动吸收波数在1560 cm-1。

With the techniques of one-step and two-step carbonization, capped and uncapped carbonization, and the modem analysis methods, the experiments on Chinese fir thinnings were performed, with special focus on the basic pyrolysis process of its saw dust and the influence on carbonized materials under different carbonization conditions. The carbon-network microstructure of charcoals developed and expanded rapidly at 600--700 ~C, and 700 ~C is the critical temperature for developing aromaticity of the charcoal. Carbon-network further expanded at 700---900 ~C, moreover, the large carbon-network with low activity of IR spectrum adsorption was formed. Charcoal carbonized by capped way in N2 atmosphere possessed large carbon-network size, and low specific surface area. On the other hand, charcoal carbonized by uncapped way or two-step way in N2 atmosphere had small carbon-network size, and large specific surface area. Then the absorption index of aromatic ring breathing of charcoal was studied, and the mechanism and variation with temperature were revealed. The carbon-network of charcoal would become larger and its structure would become more and more distorted during the carbonization process. The weak bond of the carbon-network would be broken, and thus the plane structure of carbon-network was restored. When the distortion degree of carbon-network became the highest, the absorption wave number of aromatic ring breathing was at 1560 cm^-1.