Study of Constituents of Fractionated Extraction from Datong Coal

De.2005J.China Univof Mining &Tech (English Edition)Vol 15 No 4Study of Constituents of fractionatedExtraction from Datong coalWANG Xiao-hua, WEI Xian-yongDepartment of Chemistry and Chemical Engineering, Xi'an University of Science and Technology, Xi' an, Shaanxi 710054, China2 School of Chemical Engineering and Technology, China University of mining& Technology, Xuzhou, Jiangsu 221008, ChinaAbstract: Datong coal was extracted with CS2, n-hexane, benzene, methanol, acetone, tetrahydro- furan(THF) andTHF/methanol(1: 3, v/v) mixed solvent sequentially. The extracts were analyzed with GC/MS. It is presented that groupseperation of soluble organic compounds in the coal can be achieved by fractionated extraction using different solventsThe results shoSy was effective for extracting arenes from the coal sample n-Hexane extractable fraction fromDatong coal mainly consists of n-alkanes. A great variety of oxygen-containing compounds are dominant in theponents of methanol-soluble fraction. Acyclic isoprenoids, pentecyclic triterpanes and a series of cyclohexanes withlong-chain alkyl-substitutes are detected in acetone-soluble fraction dicyclic aramaic hydrocarbons are identified inenzene-soluble fraction and 4-6 cyclic condensed aramaic hydrocarbons are identified in THF-soluble fraction. Themolecular structures detection of 1, 2-dichlorobenzene, 2, 4-dibromophnol, 2, 4, 6-tribromophenol and 4-chlorobenzophenone firstly provide information for existence form of bromine and chlorine in coalKey words: coal; solvent fractionated extraction; chemical constituent; GC/MSCLC number: TQ 5331 Introductionof extracting solubles from Datong coal. The methodtry to disrupt various secondary interactions withoutCoal solubility is the key factor of mild andcleaving covalent bonds though a series of extractionsclean conversion of coal. Solvent extract is not only with seven kinds of solvents sequentially under mildone of the effective methods to study coal chemicalcondition. Each extracting fraction was analyzed withstructure, but also a technique to achieve coal GC/MS for identification of compounds.Thedissolution. In order to select solvent with betterdistribution law of organic compound constituents insolubility under mild condition and acquire theinformation of coal structure. much work have beenmade in extracting coals and a number of methods 2 Experimentalunsoluble fractions by different solvent extracrll-oy andhave been used to investigate the coal soluble2.1 Coal sample preparationAny single solvent cannot weaken all of theThe raw coal was collected from Datong coalsecondary interactions because of various coal mine of Shanxi province, which is a typical weaklmolecular interactions of noncovalent bonds. In this caking coal in China. The coal sample was preparedpaper, multistep extraction was adopted as a method by grinding the raw coal to pass through a 200 meshReceived 10 April 2005: accepted 25 July 2005中国煤化工Projects 20076051, G1999022101, and 98029016 supported by National Natural Science FoundationState basicResearch Project, and Research Found for the Doctoral Program of Higher EducationCNMHGCorresponding author. Tel: +86-29-85583183: E-mail address: xiaohua@ vip, sinacoJ. China Univ of Mining Tech(English Edition)Vol 15 No 4sieve(<0.075mm) followed by drying in vacuum at 2.3 Components of benzene extracto for 24h. Table 1 shows the proximate andThree sorts of compounds (i.e. aliphaticultimate analyses of the coal samplehydrocarbons, aromatic hydrocarbons and hetero-Tablel Proximate analysis and ultimateatom-containing compounds) were detected inanalysis of Datong coalbenzene extractable fraction(Fig. Ib and Table 3)Proximate analysis w/soUltimate analysis wdar/%The distribution of n-alkanes with components ofbenzene extract is different from components of the2.8816.1429.5982.384.350.88244995two extracts before. Aliphatic hydrocarbons mainly1.2 Experimental methodconsist of n-alkanes with lower carbon numberDatong coal sample(10g) was extracted withPristine and phytane were still detected in the extractCS,, n-hexane. benzene, methanol. acetone. THF andthe major part appeared inTHF/methanol (1: 3, v/v) sequentially in a Soxhletaromatic hydrocarbons of the extract. Most dicyclicextractor with a water bath each extraction wasarenes have mono-and di-alkyl groups. Naphthanecarried out under boiling point temperature of eachone of the dicyclic arenes, has the highest content inextracting solvent and conducted 120 hours. Eachall the arenes detectednon-extractable residue was dried at 80 for 2h toHeteroatom-containing compounds detected inremove solvent and extracted with the next solventthe extract are oxygen-containing compoundsEach extract was concentrated with Buchi R-134including phenols and n-alkanics. Diphenyl ether wasrotary evaporator and the compositions of all extractsobserved in the extract and this is a meaningful proofwere identified with HP 6980/5973 GC/MS. All sol- that there is aromatic ether existed in Datong coalvents were analytical reagent and distilled before useTwo bromine-containing compounds, 2, 4-dibromophenol and 2, 4, 6-tribromophenol(No 9 and No 152 Results and discussionpeaks in Fig 1b), were observed firstly in the extractThe observation of these two kinds of bromine2.1 Components of CS2 extractcontaining compounds provides quite worthy inforOver 160 compounds were identified in the mation for the existence form of bromine in Datongextractable fraction. The results show that CS, extract coalmainly consist of aliphatic hydrocarbons, arenes and 2.4 Components of methanol extractheteroatom-containing compounds. Arenes areThe results from Fig lc and Table 4 show thatdominant components and most of arenes are 2-4 methanol extractable fraction almost consist of fourcycles alkyl substitutes. Aliphatic hydrocarbons pri- different types of oxygen-containing compoundsmaryly consist of n-alkanes with partial acyclic including ketones, esters, acids and amides. Ketonesisoprenoids and terpanes. Small amounts of hetero- and esters are the main part of the oxygen-containinatom-containing compoun2- compounds. Ketone-generic compounds detecteddichlorobenzene which first discovered in coal. The from methanol extract of Datong coal sample mainlydetailed test results are listed in the reference [10]include 2-, 3-and 4-methylbenzophenone, dimethyl2.2 Components of n-hexane extractbenzophenone 9(10)-acrdinone and 5(4H)-thebeniFig. la and Table 2 show that aliphatic dione, which were firstly appeared in the extractablehydrocarbons are the mainly component with fractions. Methylbenzophenones have the highestn-alkanes and biomarkers. n-Alkanes are overwhel- content in the components of methanol extract. 16mingly predominant and distribute regularly. C23, C24 kinds of ester-generic compounds, which mainly areand C25 are the center peak in Fig. la. Biomarkerlong-chain me中国煤化工 en detectedincluding pristane, phytane and hopanes( C29-C33) Methyl aliphsteHCNMH Ghe methanolwere detected in the extractextractable fraction. In addition, two acyl-compoundNG Xiao-hua et aludy of Constituents of Fractionated Extraction from Datong Coal10010(a)n-hexane soluble fraction29(b) Benzene soluble fractione100(c) Methanol soluble fraction(d) Acetone soluble fraction885ERetention time/ min(e) THF soluble fractionRetention time/ min中国煤化工(f THF/methanol soluble fractionCNMHGFiJ. China Univ of Mining Tech(English Edition)Vol 15 No 4with special structure, (z)-9-octadecenamide and 1, 5- that there is only a little compounds can be detecteddibenzoylnaphthalene, were detected firstlwith GC/MS in this extract. The major componets are2.5 Components of acetone extractpolycyclic arenes and O-containing compoundsFig ld and Table 5 display the tic and Highly condensed arenes (4-6 cyclic) are the mainidentified compounds of acetone extractable fraction. part of the compounds. Six O-containing compoundsThere is difference between the former extractable were detected including 1, 2-cyclohexanediol, 2,5fractions and acetone extractable fraction. A series of dimethylbenzophenone, 4-chlorobenzophenone(peakcyclohexanes (C17- C26) with long-chain alkyl- No 5 in Fig. le), 3, 5-androstandienone and 13-ethylsubstitutes were detected. Eight regular as well as 3-methoxyl-gona-pentaenone. All of the O-containinganti-regular isoprelwere detected too. 14 compounds above-mentioned were detected firstly interpanes have been identified including hopanes( C27, the extract from Datong coal sample except dimethylC29- C33), benzohopanes (C32- C34 )and one benzophenonearomatizational hopane (i.e. A, B, C, D- cyclicIt is significant that 4-chlorobenzophenone wastetraaromatichopane)detected because it is one of organicchlorine3-7 cyclic arenes have appeared in acetone existence form firstly observed in coalextract, which mainly are tetra- to hexa-cyclic 2.7 Components of THF/methanol extractcompounds with low content and also appeared in theThe content of detectable compounds withformer extractable fracticGC/MS in this extract is samll. All of the componentsOxygen-containing compounds detected in detected are O-containing compounds except retenecetone extract mainly are ketones and alcohols. The and the most of them are esters and ketones includingrest of O-containing compounds were firstly detected isopropyl palmitate, methyl hexadecanate, methylIn componentscetone extract except 4-methyloctadecanoatenyl eicosanate, methyl tetracosanatedinaphthofuran. Only two stigmasta-5, 22-dienol acetate, sitosterol acetateitrogen-containing compounds (i.e. 2, 6-dimethyl-6- perhydro-1-(1, 5-dimethylhexyl-tetramethyl-cyclopennitro-2-heptenone and dihydroquinoxali-no[2, 3-b] tala]cyclopropa[e ]phenanthrenone and stigmast-4-enquinoxaline) have been detected in the extract3-one. In addition, docosyloxybenzen was detected in2.6 Components of THF extractthe extract. The compounds above mentioned wereFig. le is the TIC of THF extractable fraction appeared firstly in Datong coal except methylfrom Datong coal sample and Table 6 shows the aliphatateschemical constituents of the extract. It can beTable 2 Compounds identified in n-hexane extractCompouno123456pentadecanehexadecane5678saneheptadsheptacosane2, 6, 10, 14-tetramethylpentadecaneoctacosaneoctadecane5-diene6, 10, 14-trimethyl-2-pentadecanonetriacontahentriacontanen-hexadecanoic acid17(H), 21(H)-30-norhopane01234eicosanedocotanenetricosanedocosanetricosane17(H),2中国煤化工CNMHGWANG Xiao-hua et alStudy of Constituents of Fractionated Extraction from Datong CoalTable3 Compounds identified in benzene extracttrans-decahydronaphthalenehex adecane2undecane2, 4, 6-tribromophenolnaphthaleneI-ethylpentylbenzene567890pentadecanoic acidhexadecanoic acid7-butyl-l-hexylnaphttadecanoic acidtridecanepolphenol3-pentadecylphenc23 benzo[]fluoranthene17(H),21(H)pentadecaneindeno[ 1, 2,3-cd pyrenel,’- ethvlidetdibenzoldef, mno]chryseneTable 4 Compounds identified in methanol extract(2-methylphenyl)phenylmethanone12(Z)-9-octadecenamide(3-methylphenyl)phenylmethanone13docosanoic acid methyl ester(dimethylphenyl)phenylmethanonetricosanic acid methyl esteroic acI5(4H)-thebenidinonehexadecanoic acid methyl ester16tetracosanoic acid methyl esterpentacosanoic acid methyl ester7heptadecanoic acid methyl esterxacosane acid methyl ester8-octadecanoic acid methyl esteracid methyl ester21triacontanoic acid methyl esterTable 5 Compounds identified in acetone extract202, 6-dimethyl-6-nitro-2-hepten-4-one17 (H)-22, 29,30-trinorhopane2. 6, 10. 14-tetramethylpentadecane(4-methylphenyl)-phenylmethanonemethyl-2-(4-methyl-3-pentenyl)-7-dodecyln-tridecylcyclohexane2H-1-benzpyran-5725(H).21 (H)-30-norhopanen-pentadecylcycloher2717(H).21(H)- hopane6,10,14n-heptadecylcyclohexanebenzolghilperylene17(H)21n-octadecylcyclohexaneA B C. D-ring-tetraaromatio155. 11-dihydro-quinoxalino[ 2, 3-b]quinoxaline33 17( H), 21(H)-trihomohopanen-nonadecylcyclohexane17(H).21(H)-trn-eicosylcyclohexaneoctacosane3.4: 8, 9-dibenzopyrenebenzo fluoranthenebenzohopaneTable 6 Compounds identified in THF extractCompoundsompound1, 2-cycmethylretene2 3-tert-butyl-4-hydroxyanisolebenz[]acephenanthrylene13benzole pyrene2,5-dimethylbenzophenone(4-chlorophenyl)phenylmethanonedibenzoldef, mno]chrysenebutyl-1-hexylnaphthalepyreneA, B, C, D-ring中国煤化工retene13-ethyl-3-methbenzo b]carbazole1. 2: 3. 4-dibenzCNMHG2-methylpyrene20 3. 4: 8.9-dibenzopyreneJ.China Univof Mining &Tech(English Edition)No 4Table 7 Compounds identified in THF/methanol extract1 2, 5-bis(2-methylpropyl)thiophene8methyl tetracosanatepropyl palmitatesitosterol acetatemethyl octadecanateI 1perhydro-I-(1,5-dimethylhexyl)-31, 6,6, 12ateneethyl-cyclopenta(alcyclopropa[elmethyl eicosanoatephenanthren-7-one3 Conclusionscyclohexanes with long-chain alkyl-substitutes, are1)Group coarse seperation of soluble organicdetected in acetone-soluble fraction. Dicyclaramaic hydrocarbons are identified in benzenecompounds in the coal can be achieved bysoluble fraction and 4-6 cyclic condensed aramaicfractionated extraction using different solventshydrocarbons are identified in THF-soluble fraction2)CS was effective for extracting arenes from3) The molecular structures detection of 1.2the coal sample. n-Hexane soluble fraction fromdichlorobenzene in CS, extractable fraction. 2.4-Datong coal mainly consist of n-alkanesdibromophnol and 2, 4, 6-tribromophenol in benzenevariety of oxygen-containing compoundsextractable fraction, and 4-chlorobenzo- phenone indominant in the components of methanol-solublefraction. The functional groups in oxygen-containingTHF extractable fraction firstly provide very worthyinformation for existence form of bromine andcompounds detected mainly are carbonyl, carboxylic,chlorine in coalhydroxnoids, pentacyclic triterpanes and a series of[1] lino M, Takanohashi T, Obsuga H, et al. 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