Wb. Li et al., DETERMINATION OF VOLATILE HYDROCARBONS IN COALS AND SHALES USING SUPERCRITICAL-FLUID EXTRACTION AND CHROMATOGRAPHY, Energy & fuels, 11(5), 1997, pp. 945-950
Conventional analytical techniques, such as headspace gas chromatograp
hy and Soxhlet extraction, can provide compositional information for t
he gaseous (C1-5) and heavy (C15+) hydrocarbon constituents, respectiv
ely. The volatile (C6-14) hydrocarbons, if present, usually go undetec
ted because of volatility fractionation and loss. In this study, super
critical CO2 was used to extract the C-6-C-14 volatile hydrocarbons fr
om pulverized coal samples. Capillary column gas chromatography/mass s
pectrometry was used to identify the mixture components, and packed ca
pillary column supercritical fluid chromatography was used to separate
and quantify the aliphatic and aromatic hydrocarbon class fractions.
It was found that the compositions of the light hydrocarbon fractions
included several homologous series of normal and branched aliphatic hy
drocarbons, cyclic and aromatic hydrocarbons, and alkyl-substituted be
nzenes and naphthalenes; the concentrations of these volatile hydrocar
bons ranged between 0.01 and 0.2 wt % of the bulk material for differe
nt coal and shale samples.