Microstructure characteristics of lignite under the synergistic effect of oxidizing acid and ionic liquid [Bmim][Cl]. (1st April 2021)

• Record Type: Journal Article
• Authors: Shang, Li; Guanhua, Ni; Baisheng, Nie; Shouqing, Lu; Xijian, Li; Gang, Wang
• Is Part Of: Fuel. Volume 289(2021)
• Publication Date: 2021-04-01
• Subjects: Oxidizing acid -- Ionic liquid -- Synergistic effect -- Functional groups -- Microcrystalline structure; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2020.119940
• Languages: English
• ISSNs: 0016-2361

Abstract

Highlights: HNO3, [Bmim][Cl] and HNO3 /[Bmim][Cl] can promote the aromaticity of coal. The synergistic effect makes the aliphatic structure easier to fall off. The synergistic effect makes the microcrystalline structure more graphitized. The presence of [Bmim][Cl] can delay the oxidation process of HNO3 . Abstract: In order to investigate the evolution characteristics of coal microstructure under the synergistic effect of oxidizing acid and ionic liquid, in this paper, the microcrystalline structure and functional groups of coal were modified with HNO3, [Bmim][Cl] and HNO3 /[Bmim][Cl], respectively. Fourier transform infrared (FTIR) spectroscopy combined with X-ray diffraction (XRD) was used to collect the microstructure information of coal samples and obtain the variation of microstructure parameters. The research showed that compared with the single treatment method of HNO3 and [Bmim][Cl], the synergistic treatment of HNO3 /[Bmim][Cl] makes the molecular structure of coal extremely unstable, and the aliphatic chain and aliphatic side chain are easier to fall off and condense from the main structure of coal molecules, which further increases the aromaticity of coal. Meanwhile, [Bmim][Cl] can dissolve and remove some active functional groups and delay the oxidation process of HNO3 . For the microcrystalline structure of coal, all three solvents can reduce the interlayer spacing (d002 ), increase the average lateral size (La ), the effective stacking layer number (N) and the stacking height (Lc ), indicating that the solvent treatment makes the microstructure more compact. As the synergistic treatment of HNO3 /[Bmim][Cl] promotes the aromatization process of coal microstructure and significantly reduces the aliphatic content, the coal microcrystalline structure tend to graphitization.