[Terrapreta] micro-porosity: char vs. charcoal

[Gerald Van Koeverden]

Micro-porosity seems to take extended periods of time to develop  
properly...so that charcoal as produced in reactors will probably be  
very porous.  But what about char?  It only spends a second or two in  
the furnace...?

Gerrit

At 250ºC for heating times up to 144 hours, and at 300ºC for heating  
times up to 24 hours, the micropore volume remained below the  
detection level. At 300ºC for heating times of 48 and 72 hours, the  
micropore volumes were 0.043 and 0.072 cm3/g, respectively. At 350ºC,  
the micropore volumes were <0.001, 0.070, and 0.222 cm3/g when heated  
for 1, 8, and 24 hours, respectively. At 400ºC, the micropore volumes  
were <0.001, 0.201, and 0.306 cm3/g when heated for 1, 8, and 24  
hours, respectively. At 500ºC, the micropore volumes were 0.079, and  
0.209 cm3/g when heated for 1, and 8 hours, respectively."

from: Changes in Composition and Porosity Occurring During the  
Thermal Degradation of Wood and Wood Components

By David W. Rutherford, Robert L. Wershaw, and Larry G. Cox

    http://pubs.usgs.gov/sir/2004/5292/#N100B0
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