Carbonization experiment
The carbonization processes of the samples were carried out in
a vertical quartz tube reactor with the body length of 970 mm and
the internal diameter of 35 mm. There was a quartz frit used as a
gas distributor in the center section of the tube reactor. The tube
reactor was heated by an electric furnace (Temperature precision
1 C) based on the designed procedures. During every run, about
40 g dried sample was loaded on the quartz frit in the quartz tube.
A flow of dry nitrogen (99.999%, 200 ml/min) was purged into
the tube reactor to provide an inert atmosphere. A gas chromatograph
(GC2014, Japan SHIMADZU company) was used to test the
oxygen in the outlet gas. When there was no O2 determined in
the outlet gas, the reactor was heated from room temperature to
the designed final temperature at 10 C/min and held at the temperature
for 30 min to ensure no volatile emission. The final temperature
range was from 400 C to 800 C. At the end of each run,
the reactor was cooled down in nitrogen atmosphere to room temperature
and the char prepared was collected and weighed to calculate
the char yield. Then, the char was ground to pass through a
150-mesh sieve (60.1 mm) and placed in the drying oven of 105 C
for the subsequent analysis experiment.