Generation of adamantanes and diamantanes by thermal cracking of high-molecular-mass saturated fractions of crude oils of different genotypes

Abstract

The thermal cracking of high-molecular-mass paraffin-cycloparaffin fractions (bp above 350°C) of oils of different genotypes was carried out. Although the >350°C fraction contains neither adamantanes C 10 -C 14 nor diamantanes C 14 -C 16 , which boil in the range 190–286°C, they are generated again during the thermal cracking of high-molecular-mass paraffin-cycloparaffin fractions. Thus, it was first shown that hydrocarbons with the adamantane and diamantane moieties are present in the >350°C fraction. The distribution of C 10 -C 13 adamantanes in crude oils correlates well with that in the products of the thermal cracking of high-molecular-mass (>350°C) saturated fractions, thus indicating a relation between the high-molecular-mass hydrocarbon portion containing the adamantane moiety and C 10 -C 13 adamantanes in the oils. There is no such correlation for the distribution of diamantane hydrocarbons of the C 14 -C 16 series.