科研之友
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摘要
In our previous work, we demonstrated a novel two-step pyrolysis method that increased the final char yield. The control of the final structure is another crucial issue in charcoal making. No structural study has yet been performed on charcoal produced by this two-step pyrolysis method. Here, we conducted two-step pyrolysis experiments (a pyrolysis step at 360 degrees C, followed by a carbonization step at 900 degrees C) on 102 cubes of eucalyptus wood samples. We selected carbonized charcoals (after two-step pyrolysis) that had different solid residue yields at the end of the first pyrolysis step to monitor the changes in their texture and structure using visual inspection, infrared spectroscopy (IR) and X-ray diffraction (XRD) analysis. Visual inspection showed different texture categories in terms of the carbonized charcoal defects, depending on their solid residue yield at the end of the first step: samples that were swollen and burst, samples that were split and samples that showed no abnormal defects. The IR spectra of the resulting carbonized charcoals showed no significant differences in their chemical structure. Conversely, their XRD patterns showed that the increase in char yield was accompanied by an increase in the formation of graphite crystallites. In particular, graphite crystallite formation was optimized for charcoals obtained by applying the second pyrolysis step when their solid residue yield was approximately 50% at the end of the first step. These findings open up new areas of exploration for in-depth studies to control the structure of charcoal.
- 出版日期2014-9
