Chemical Composition and Their Geochemical Feature in Two Special Coal Extracts of Hunyuan Coal and Lupinite-Alkane Fraction

Abstract: The present paper investigated the extracts of mathanol-benzene soxhlet extraction for two extraordinary coals, namely, a Hunyuan algel candle in Shanxi Province and Lupinite in Jiangxi Province. by means of gas chromatography, and GC/MS techniquts. The chemical structures and configulation were identified by Kovats Values of gas chromatograms, mass chromatograms and the interpretation of mass fragmentagrams. The occurrence and distrbution feature of alkanes, isoprenoids, alkyl cycolhexanes, terpanes and steranes have been investigated. The correlalionship between some geochemical parameters and precursor of coal-original as well as sedimentary environment was discussed. Hunyuan algal candle is a sapropelic coal with higher H/C and O/ C atomic ratios(1.13 and 0.18 respectively) and there are many algae and waxes under the microscopic study. The conspicuously present of 17αH, 18αH, 21βH-28, 30-C₂₈ bisnorhopane, gammacerane and γ-carotane have been firstly identi fied in this kind of boghead coal. Some geochemical parameters, such as pristane/phytane = 0.5, ∑ C₂₀/ ∑C₂₀+= 1. 04, C₂₉-xxx-( R+ S)/C27- xxx-( R+ S) = 1. 66, index of gammacerane(gammacerane/ C₃₀-xβhopane) =0.23, the ratio of 22S to 22R for C₃₂-C₃₅ hopane 1 and a few percentage of C₁₅-C₂₂ alkylcyclohexane as well as completely sterane system indicated that the paleoenvironment of Hunyuan algal candle was a reducing environment covered by saline water, the main input precursor is higher plant followed by algae and bacteria. Lupinite from Jinxi is an unique bark coal which is referred as Lupinite as new coal macerals in the petrography. In the alkane fraction of benzene- methanol extract from Lupinite, there are some geochemical characters as follows: a lack of sterane system is a quite special case in the coal extraction. n-C₁₆0is main component in the normal alkane, ∑C₂₀-/ ∑ C₂₀+= 3.2, Pr/Ph= 1.3, C₁₂-C₂₀ alkyl cyclohexane account 4%, the distribution of carbon number of alkyl cyclohexane as same as normal alkane, but the main peak is C₁₅, one carbon number less than normal alkane. The ratio of 22S to 22R for C₃₂-C₃₅ hopane 1. The microscopic study indicated that Lupinite consists mainly of suberinite of Lepidodendrales and ferns as the primordial plant debris(account 50-70%) with decken structure due to paralic deposit environment in which both aerobic and anaerobic environment would be alternatively existed, therefore, both aerobic and anaerobic bacteria attacked the plant debris where completely decomposition of celluloses and lignin would be happened and only preserved stable exinite and suberinite as resi dues.