Chemical and pyrolytic thermogravimetric characterization of Nigerian bituminous coals

Abstract

The discovery of new coal deposits in Nigeria presents solutions for nation’s energy crises and prospects for socioeconomic growth and sustainable development. Furthermore, the quest for sustainable energy to limit global warming, climate change, and environmental degradation has necessitated the exploration of alternatives using cleaner technologies such as coal pyrolysis. However, a lack of comprehensive data on physico-chemical and thermal properties of Nigerian coals has greatly limited their utilization. Therefore, the physico-chemical properties, rank (classification), and thermal decomposition profiles of two Nigerian bituminous coals – Afuze (AFZ) and Shankodi-Jangwa (SKJ) – were examined in this study. The results indicate that the coals contain high proportions of C, H, N, S, O and a sufficiently high heating value (HHV) for energy conversion. The coal classification revealed that the Afuze (AFZ) coal possesses a higher rank, maturity, and coal properties compared to the Shankodi-Jangwa (SKJ) coal. A thermal analysis demonstrated that coal pyrolysis in both cases occurred in three stages; drying (30-200 °C), devolatilization (200-600 °C), and char decomposition (600-1000 °C). The results also indicated that pyrolysis at 1000 °C is not sufficient for complete pyrolysis. In general, the thermochemical and pyrolytic fuel properties indicate that the coal from both places can potentially be utilized for future clean energy applications.