Comparison of the effect of minerals on aromatization reactions during kerogen pyrolysis

Rundle shale from Queensland Australia (aromaticity, f a = 0.21) has been pyrolysed at 450 °C. About 19% of the aliphatic carbon is converted to aromatic carbon. When the shale is demineralized and the kerogen also pyrolysed at the same temperature, aliphatic carbon in the kerogen is still converted to aromatic carbon, and in about the same proportion (23%). The addition of montmorillonite, pyrite, monazite, orthoclase, calcite, charcoal and potassium bromide does not increase aromatization of the kerogen. However, the minerals do alter the yield of oil and increase the ratio of external to internal alkene protons in the oils. This contrasts with strong cracking catalysts which increase internal alkene protons at the expense of external alkene protons.