Composition Distribution of the Thermal Soluble Organics from Naomaohu Lignite and Structural Characteristics of the Corresponding Insoluble Portions

• Published in: Molecules (Basel, Switzerland) Vol. 29; no. 12; p. 2776
• Main Authors: Zhu, Meixia, Ma, Yaya, Mo, Wenlong, Hao, Shihao, Wei, Xianyong, Fan, Xing, Ren, Tiezhen, Ma, Kongjun, Guo, Jia
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 11-06-2024; MDPI
• Subjects: Acids; Alcohol; Carbon; Chemical bonds; Chemical industry; Coal; composition and structural characteristics; Energy consumption; Esters; Ethanol; Hydrocarbons; Hydrogen bonds; Lignite; naomaohu lignite; Phenols; Pyrolysis; soluble organics; Solvents; thermal dissolution; China; thermal dissolution; composition and structural characteristics; soluble organics; naomaohu lignite
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules29122776

With cyclohexane (CH), benzene (BE), and ethyl acetate (EA) as solvents, Naomaohu lignite (NL, a typical oil-rich, low-rank coal) from Hami, Xinjiang, was thermally dissolved (TD) to obtain three types of soluble organics (NL
, NL
, and NL
) and the corresponding insoluble portions (NL
, NL
, and NL
). Ultimate analysis, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG-DTG), and gas chromatography-mass spectrometry (GC/MS) were used to characterize NL and its soluble and insoluble portions. Results showed that, compared with NL, the C element in NL
, NL
, and NL
increased, while the O element decreased significantly, indicating that thermal dissolution is a carbon enrichment process and an effective deoxidation method. The GC/MS results showed that oxygen-containing organic compounds (OCOCs) are dominant in NL
, NL
, and NL
. NL
is mainly composed of ketones (11.90%) and esters (19.04%), while NL
and NL
are composed of alcohols (12.18% and 2.42%, respectively) and esters (66.09% and 84.08%, respectively), with alkyl and aromatic acid esters as the main components. Among them, EA exhibits significant selective destruction for oxygen-containing functional groups in NL. XPS, FTIR, and TG-DTG results showed that thermal dissolution can not only affect the macromolecular network structure of NL, but also improve its pyrolysis reactivity. In short, thermal dissolution can effectively obtain oxygen-containing organic compounds from NL.