The physical character of coal char formed during rapid pyrolysis at high pressure

Rapid pyrolysis was conducted in a drop tube reactor using seven coals under various operating conditions. In addition to dense char, porous chars (network char and cenospheric char) were formed by the rapid pyrolysis under certain conditions. Porous char was mainly composed of film-like carbon and skeleton carbon. The pyrolyzed coal char particles were characterized in detail. Morphology and bulk density of porous char were quite different from the dense char formed under the same conditions, but elemental composition and BET surface area were similar to each other. CO2 gasification reactivity of porous char was lower than dense char in the later gasification stage, and this was ascribed to the low reactivity of skeleton carbon.