白音华褐煤可溶有机质的组成和结构特征

依次采用石油醚、环己烷、二硫化碳、丙酮、甲醇和等体积的丙酮/二硫化碳混合溶剂对白音华褐煤(BL)进行分级萃取得到萃取物(E_1-E_6),利用甲醇、甲苯和等体积的甲醇/甲苯混合溶剂对萃取残渣进行连续热溶得到热溶物(SP_1-SP_3)。利用傅里叶变换红外光谱(FT-IR)、气相色谱质谱(GC/MS)和实时直接分析-质谱(DART-MS)对萃取物和热溶物的组成和结构特征进行了分析。BL总的萃取物产率和热溶物产率分别为9.37%和21.84%。E_5和E_6的FT-IR谱图中有较强的羟基吸收峰,而E_1的FT-IR谱图中脂肪C-H的伸缩振动峰强度明显高于其他萃取物;三种溶剂热溶物的FT-IR谱图相似,但SP_1和SP_3的FT-IR谱图中羟基吸收峰较强。E_1和E_5中GC/MS可检测化合物分别以烷烃和芳烃为主,E_5中还含有较多的含氧化合物;三种热溶物中化合物均以烷烃和芳烃为主,SP_3中酚类、酮类和酯类等含氧化合物的含量较高。DART-MS可检测出萃取物和热溶物中GC/MS无法检测出的较强极性和难挥发化合物;热溶物中含量较高的化合物的碳数和等价双键数(Double bond equivalent,DBE)分别集中分布在10-25和2-16,并且DBE随碳数增加而增加。

Composition and structural characteristics of soluble organic species in Baiyinhua lignite

Baiyinhua lignite was sequentially extracted with petroleum ether, cyclohexane, carbon disulfide, acetone, methanol and isometric acetone/carbon disulfide mixed solvent affording extracts, i.e. E₁-E₆, then extraction residue was sequentially thermal dissolved using methanol, toluene and isomeric methanol/toluene mixed solvent affording soluble portions (SPs), i.e.SP₁-SP₃. The composition and structural characteristics of extracts and SPs were characterized with Fourier transform infrared (FT-IR) spectroscopy, gas chromatography/mass spectrometer (GC/MS), direct analyze in real time mass spectrometer (DART-MS). The total extracts yield and SPs yield of BL are 9.37% and 21.84%, respectively. There exist strong adsorption peaks ascribed to hydroxyl in the FT-IR spectra of E₁ and E₆, while the intensity of adsorption peaks ascribed to aliphatic C-H in the FT-IR spectrum of E₁ is obviously higher than that of other extracts. There are similar FT-IR spectra among those 3 SPs, whereas the intensity of adsorption peak originated from hydroxyl in the FT-IR spectra of SP₁ and SP₃ is higher than those of SP₂. The compounds GC/MS detected in E₁ and E₅ are dominated with alkanes and arenes, respectively, and the content of oxygen-containing compounds (OCCs) in E₅ are more than that in E₁. The compounds in the 3 SPs are composed of alkanes and arenes, while the contents of OCCs, such as phenols, ketones and esters, in SP₃ are higher than those in SP₁ and SP₂. Many compounds with high polarity and low volatility which could not identified by GC/MS were detected using DART-MS. The carbon number and double bond equivalent (DBE) of the compounds with high content in SPs mainly distribute in 10-25 and 2-16, respectively, and the DBE increases with carbon number increasing.