Trace impurities in Canadian oil-sands,coals and petroleum products and their fate during extraction,up-grading and combustion

National energy programs for the next two decades entail increased total consumption of fossil fuels in general and, in particular of portable fuels extracted from oil sands and shales and from lower quality coals. Improved fuel-upgrading and combustion technologies are recognized to be vital for minimizing environmental degradation caused by continental and global acid-rain precipitation from fossil-fuel impurities. A further consideration, however, is the fate of those trace-element co-contaminants of acid-rain such as heavy metals, which are present at lower concentrations (10⁻⁴–10⁻⁷) but may also be of environmental significance when 10⁷ to 10⁹ tons·y⁻¹ are utilized on several continents. In this laboratory, INAA procedures have been adapted for the determination of 25–30 trace impurities in a variety of fuels and extracts including: S, V and Al, As, Ba, Br, Ca, Ce, Cl, Co, Cr, Dy, Eu, Fe, Hf, K, La, Mn, Na, Rb, Sb, Sc, Sm, Th, Ti, U. Samples were obtained of typical Canadian pumped crudes, and from several Canadian oil-sands and coal deposits (mostly bituminous and subbituminous) both in their natural states and after stages of extraction and upgrading. Also analyzed were fuels derived from them and the residues resulting from their refining and combustion. InAA of all fossil fuel extracts including light oils, viscous bitumen and such organic fluids could be performed under the same conditions as the parent substances: crude oils, oil-sands and coals, without any special sample preparation. Although no standard samples are routinely required because of the 1–2% long-term flux stability of the reactor, accuracy checks were performed periodically by reference to NBS-1632A standard coal and atomic absorption standard dilute solutions. Results obtained for the NBS coal SRM and the BAM flyash sample (1978) are also given. A wide range of trace impurities determined in the Canadian fossil fuels included some of those which are of particular significance in Canadian coals and their ashes (a STM standard ashing method). The ‘inorganic’ traces can also be grouped according to their fate during static combustion at 750°C. The research reported here was supported with funds from a Natural Sciences and Engineering Research Council of Canada Strategic energy grant (G 0017), 1978–80, “Trace Contaminants of Environmental Importance in Present and Future Fossil Fuels”.