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

With the techniques of one-step and two-step carbonization,capped and uncapped carbonization,and the modern 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 ℃,and 700 ℃ is the critical temperature for developing aromaticity of the charcoal.Carbon-network further expanded at 700—900 ℃,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.