Assessing the closed-pore content in coal at different metamorphic stages

Abstract

The pore structure of coal samples at different metamorphic stages (D, DG, GZhO, Zh, K, KS, and OS coal) is studied by the low-temperature adsorption of nitrogen, mercury porosimetry, and measurements of the actual density. On that basis, the quantity of closed pores in the samples is estimated. The number of pores, their size, and the total pore volume are found to depend on the coal’s metamorphic stage. The pore size and total pore volume tend to increase at later metamorphic stages, whereas the number of closed pores declines. If coal is adopted as a model system, the results may also be used in studying the morphology of nanostructured carbon materials such as nanofibers and nanotubes.