Abstract
The changes in pore structure of six kinds of Japanese coals heat treated up to 900°C were measured by the absorption of carbon dioxide at 298°K and 273°K.
The micro-pore volume, the parameter of static pore size distribution, and the parameter of dynamic pore size were calculated from the intercept and gradient of Dubinin-Polanyi equation and the ratio of the amounts adsorbed during first 10 minutes to those of equilibrium state.
The micro-pore volume decreased slightly with the increase of HTT and showed a minimum at about 400°C. Then increased to about 600°C in all the samples investigated. At the higher temperature than about 600°C, the values of coals of higher rank than 85%C decreased sharply with the increase of HTT, but those of coals lower rank than 85%C flattened off or increased slightly.
It was found that the changes of pore structure were mainly due to the oozing out of tarry materials, demethanation, dehydrogenation and thermal shrinkage, in the range of HTT of about 100-400°C, about 400-700°C and above about 700°C, respectively.
