Variation in hydrogen content of vitrinite concentrates with rank advance

Vitrinite concentrates isolated from Indian Permian coals with mean random reflectance (Rr) ranging from 0.52% to 1.92% have been subjected to petrographic and ultimate analyses. The data set of vitrinite concentrates created has been used to study the variations of various chemical rank related parameters, viz. C, atomic O/C ratio, atomic H/C ratio and H, with Rr. The variations of C, atomic O/C and atomic H/C have manifested as continuous polynomial functions, while the variation of H is distinctly different. H is found to increase initially with Rr up to 0.9% Rr and then decreases with rank advance. The variation suggests maturation of vitrinite in the rank range has taken place via two distinct yet contiguous phases. The first phase of evolution is characterized by loss of oxygen with enrichment of hydrogen, while the second phase is marked by loss of hydrogen. The evolved phases could be best described by equations linking Rr with elemental composition as: Rr = −2.1618 + 0.0329C + 0.0285H (C < 85%) and Rr = −2.7569 + 0.0648C − 0.3350H (C > 85%), where C and H stand for % carbon and % hydrogen, respectively on dmmf basis.