DISTRIBUTION OF OXYGEN FORMS IN ALBERTA LOW RANK COALS

The partitioning of oxygen contents between oxygen-bearing functional groups in a suite of Western Canadian low rank coals and in some representative Carboniferous and Cretaceous bituminous coals has been studied. Distribution of [O] between [O(COOH)], [O(OH)], [O(CO)] and a nominally unreactive [O(resid)] not encompassed by the three reactive entities suggests considerable chemical diversity among analytically similar low rank coals and may go some way towards explaining the frequently quite disparate behaviour of such coals in chemical processing. Additional causes of such disparate behaviour may lie in the dissimilarly changing relative concentrations of [O(COOH)], [O(OH)], [O(CO)] and [O(resid)] during mild pyrolysis to 300-degrees-C. These changes reflect significant, but seemingly rank-independent structural alteration of the coal substance at temperatures far below the onset of active decomposition (usually placed at or near 400-degrees-C). The possible beneficial impact of partial thermal deoxygenation (by removal of -COOH) on hydrogen traffic in subsequent coal processing is briefly noted.