Molecular probe chromatography of bituminous coal

Abstract

The properties of some bituminous coals and an anthracite have been studied by “Molecular Probe Chromatography” using selected probes. Irrespective of the rank of coal, some behaviour common to all has been found. Following the sorption of air components and carbon dioxide at ambient temperature, interesting flow-disturbed peaks have been observed. Unlike the behaviour observed on a freshly packed column, both the retention and peak asymmetry of carbon dioxide increase upon column conditioning. The probe molecules, irrespective of their chemical identity, are sorbed on the surface by adsorption alone, up to 175°C. The probes are retained in the column both by specific and non-specific interaction forces and the contribution of the former to retention predominates in low rank coal. The selectivity of carbon dioxide at ambient temperature, and the retention of water and methanol at 175°C are dependent on the rank of coal. This dependence is similar to the porosity—rank relationship of coal. The permeability of bituminous coal decreases progressively with rank.